Coronary Heart #18

Liverpool Heart and Chest NHS Trust

coronaryheart.com

ECG Challenge

Inside

May / June 2009Issue 1� May / June 2009Issue 1�

Hot TopicFFR FAME trial results (Part 2) with opinions from 2 leading cardiologists.

Behind the ScenesClinical Education withSt Jude Medical, UK.

New TechnologyA basic introduction toCardiac MRI.

Site VisitThe Liverpool Heart and Chest Hospital

ConferencesBCS Conference Overview

EP EducationAtrial Tachycardia

Drug FocusRenolazine

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ContentsCONTENTS

Cover Photo: Dr Scott Murray at the Liverpool Heart and Chest NHS Trust

Disclaimer:Coronary Heart should never be regarded as an authoritati ve peer reviewed medical journal. Coronary Heart has been designed as a guide only, to inform readers who work in the cardiology environment about latest news stories and the diff erent techniques used by others around the world. Whilst all care is taken in reviewing arti cles obtained from various companies and contributors, it is not possible to confi rm the accuracy of all statements. Therefore it is the reader’s responsibility that any advice provided in this publicati on should be carefully checked themselves, by either contacti ng the companies involved or speaking to those with skills in the specifi c area. Readers should always re check claims made in this publicati on before employing them in their own work environment. Opinions expressed by contributors are their own and not necessarily those of their insti tuti on, Coronary Heart Publishing Ltd or the editorial staff .

18 Site Visit- � e Liverpool Heart and Chest NHS Trust

Coronary Heart Publishing Ltd145 - 157 St John Street

London, EC1V 4PYUnited Kingdom

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CIRCULATION3500 Cardiac Professionals

Copyright © 2006 -2009 by Coronary Heart Publishing Ltd.

All rights reserved. Material may only be reproduced by prior arrangement and with due acknowledgment of Coronary Heart Publishing. The publication of an

advertisement or product review does not imply that a product is recommended by Coronary

Heart Publishing Ltd.

Low Advertising Budget?

Coronary Heart is widely regarded as the favourite dedicated UK cardiology publicati on for the enti re cardiac department. Each editi on is developed with the reader in mind with interesti ng arti cles and innovati ve designs.

We have a variety of adverti sing opti ons to match your budget, including sponsorships and content matching placements. Our team fi rmly believe in building strong relati onships with all adverti sers which is why our director Tim Larner will personally meet with you to answer any questi ons you have and assist you in achieving your marketi ng goals. The coff ee’s on us!!

See our current adverti sers on page 29.

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04 Latest News

06 Hot Topic

08 Journal Trawl

09 ECG Challenge

10 Behind the Scenes at SJM

12 BCS Conference Preview

14 Intro to CMRI

17 Drug Focus

22 EP Education- Atrial Tachycardia

28 ECG Challenge Answer

30 Next Issue,Events & Recruitment

Liverpool Heart and Chest Hospital

FEATURES:

COVER STORY:

Page 18

CORONARY HEART ™ 3

LATEST NEWS

- The Team -Mr Tim LarnerDirector/Chief EditorCentral Manchester University Hospitals NHS Foundation Trust

Dr Simon RedwoodChief Clinical EditorGuy’s & St Thomas’ NHS Foundation Trust

Dr Rodney FoaleSenior Clinical EditorImperial College Healthcare NHS Trust

Dr Richard EdwardsConsulting EditorNewcastle upon Tyne Hospitals NHS Trust

Dr Divaka PereraConsulting EditorGuy’s & St Thomas’ NHS Foundation Trust

Dr John PaiseyJournal EditorRoyal Bournemouth and Christchurch Hospitals NHS Foundation Trust

Mr Ian WrightChief EP Consulting EditorImperial College Healthcare NHS Trust

Mr Adam LunghiEcho EditorCVS - CardioVascular Services, Australia

Mr Stuart AllenCRM EditorMonash Medical Centre, Australia

Ms Mojgan SaniPharmaceutical EditorRoyal Berkshire NHS Foundation Trust

Three more centres now have Vol-cano’s Integrated Multi -Modal-

ity platf orm in the United Kingdom; Birmingham Heartlands, Castle Hill Hospital in Hull and The London Chest Hospital all had their new systems in-stalled during the last three months. These centres then join the extensive and rapidly growing group of hospitals around in Europe enjoying the benefi ts of fully integrated multi -modality diag-nosti c systems. The Volcano systems are easy to use and save ti me because they are always on and always avail-able, no longer does anyone have to leave the Catheter Lab to fi nd the IVUS or FFR system parked in some out of the way corner.

The latest Volcano Systems off er Rota-ti onal IVUS, Solid State grayscale IVUS in additi on to their novel VH IVUS tech-nology enabling users to discriminate between various types of plaque. Their latest systems now also include FFR to off er complete lesion assessment in-tegrated into the Lab. To support their new systems Volcano off er extensive on site training through their Product Specialists. In additi on Volcano also run a European Preceptorship Programme which is available to all their custom-ers. Full informati on on all Volcano products is available on their website www.volcanocorp.com or via their local representati ves.

Volcano Integrated IVUS/FFR Systems

4 CORONARY HEART ™

LATEST NEWS

Latest News

Left: Chris Abell and Dr Rod Stables (right) with the ACIST Contrast Delivery System

CORONARY HEART ™ �

The ACIST Contrast Delivery System moves angiography into the 21st century. In addition to providing superior images, the

ACIST provides extra safety for both patient and physician.

Exclusively from APC Cardiovascular.Please visit www.apc-cardiovascular.co.ukor call 01270 216142 for more details.

The Liverpool Heart and Chest Centre are using the ACIST for interventional cases.

The Liverpool Heart and Chest Centre is one of the largest and most prestigious cardiac centres in the UK. They im-

plant 1200 pacemakers and ICDs per year and perform 2500 PCIs annually.

The Centre recently installed the ACIST Contrast Management System. The ACIST helps clinicians perform both diagnostic and interventional procedures. Dr Rod Stables, interventional car-diologist, says, ‘the safety systems on the ACIST, coupled to the fact that there is no need to disconnect and reconnect tubing, virtually eliminate any air embolus risk. Additionally the physi-cian can stand further away, thus reducing radiation exposure’.

Another of the benefits of the system includes features de-signed to save contrast. Dr Stables comments ‘Contrast doses are controlled and recorded with great accuracy, resulting in re-duced patient dose’.

Superintendent Radiographer Chris Abell agreed, saying ‘that while contrast doses are kept to an absolute minimum, the improved opacification has resulted in a higher standard of angiography’. Chris also added ‘We have found the ACIST to be versatile, allowing different techniques to be combined efficiently and is particularly successful with rotational angiography where filling of the coronary vessels is prolonged for the duration of the rotation, so anatomy is well demonstrated from start to finish.

Chris also noted the potential benefits when performing primary angioplasty, ‘our newly introduced primary service will really ben-efit from the built-in safety features coupled with reduced contrast dosing’.

The Liverpool Heart and Chest Hospital is this issue’s Site Visit. Refer to page 18.

HOT TOPIC

Dr Richard Carroll MB ChB MRCPConsultant Interventional CardiologistImperial College Healthcare NHS TrustLondon, UK

The overreaching principle behind the management of coronary artery disease is the reduction in the risk

of myocardial infarction, the prolonga-tion of survival and control of symptoms of angina. The body of evidence for im-proved survival comes from medical therapy with agents such as statins and ACE inhibitors. We perform percutaneous coronary intervention (PCI) for the relief of the symptoms of angina. Depending on local access to catheterisation labo-ratories, there is a significant variation in the way patients access PCI. In areas with high access, the patient may be offered di-agnostic angiography and proceed to PCI relatively early on in the course of their condition. In areas where there is less ac-cess, they may reach the catheterisation laboratory only after they have exhausted medical therapy.

The FAME study, although well constructed and compelling, cannot be interpreted in isolation. Current evidence supports that in the vast majority of patients PCI does not improve survival. The most contem-porary of these studies is the COURAGE trial, which underscores previous smaller trials indicating no survival benefit for PCI versus best medical therapy. The major-ity of patients we now see in the lab have multivessel coronary disease, often with one clear critical stenosis and one or more intermediate or tandem stenoses. It is in these very patients that the FAME investi-gators attempted to evaluate if PCI guided by FFR provided a benefit to PCI guided by angiography only.

We have already seen from the DEFER study that in Patients with single vessel disease, PCI of stenoses with FFR>0.75 does not improve symptoms or survival and may indeed result in an adverse MACE for the patient. Moreover, patients with significant stenoses (FFR>0.75) had elevated event rates over 5 years even if stented. This reflects existing data from myocardial SPECT studies: ie if there is in-ducible ischaemia: stent, if not, don’t.Perhaps what FFR actually gives us is an in-lab tool for the detection of ischaemia in those patients who do not have good non-invasive data before catheterisation. Perhaps it allows us to address the axiom that, at least for now, with PCI, the less the better.

A number of questions remain unan-swered: FAME investigators used FFR of 0.8 as the cut of point, most clinicians in Europe use FFR 0.75. It would be logical to assume that if 0.75 had been used, the results may have differed significantly. It would be important to know what propor-tion of patients fell in that 0.75-0.8 group, to name but one.

I have used FFR in the laboratory for eval-uation of intermediate lesions for several years. It is an extremely useful adjunct to the clinical decision making process in those 60+ % lesions where the symp-toms are convincing but the lesion is not and there is no non-invasive data. If the symptoms are good, I will analyse lesions of lesser angiographic severity and often am surprised with two or more reproduc-ible FFR readings indicating significance. I never use FFR to analyse the clearly sig-nificant lesions. In a lab with staff accus-tomed to FFR measurement it is quick and effective.

In conclusion, my practice shall not change as a result of FAME. I see the results as an endorsement of the use of FFR in those lesions which are of intermediate an-giographic severity, but will not find my-self putting a pressure wire down those lesions which clearly present a severe angiographic stenosis in the near future.

“The FAME study showed that routine FFR significantly improved outcomes after (DES) stenting in Multi-Vessel Disease. Do you currently routinely use FFR when stenting equivocal lesions and will results from the FAME trial have an effect on your work practices?”

Cardiologist Hot Topic

Part 2

Dr Rod StablesConsultant Interventional CardiologistLiverpool Heart and Chest Hospital NHS Trust, Liverpool, UK

We have been regular users of FFR tech-niques and FAME serves mainly to justify our current approaches. Beyond FAME I think flow reserve has much to offer in the identification of epicardial vessel flow limitation due to long segment disease rather than focal stenoses.

Part One of this Hot Topic can be found in the previous edition with responses from Prof Adam Timmis and Dr Magdi El-Omar.

� CORONARY HEART ™

Radi was the first company to develop a pressure guidewire which facilitated the development of Fractional Flow Reserve (FFR). We are Radi Medical Systems AB, founded in Uppsala, Sweden in 1988.

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The future of FFR is coming soon.

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JOURNALS

� CORONARY HEART ™

Previous research on the polypill has been in the form of model-ling. A clinical study has now been

performed to assess safety and surrogate endpoints. Middle aged individuals with at least one risk factor were randomised to polypill or its constituents (Simvasta-tin, aspirin, thiazide, atenolol and rami-pril) alone or in combination. The polypill was effective at treating endpoints and well tolerated.

The Indian Polycap Study. The Lancet, 2009, 373; 9672: 1341 –1351

Catheter ablation of atrial fibrillation is a growing area of practice but the proce-dural endpoints are variable with some advocating ablation of complex fraction-ated atrial electrograms, certain extrem-ists even without pulmonary venous isolation.

In a study of persistent AF patients not cardioverted by PVI randomised to CFAE ablation or no further ablation there was no difference in AF free survival, although both groups were significantly less likely to remain in sinus rhythm than those who cardioverted during PVI.

H Oral and others J Am Coll Cardiol, 2009; 53:782-789

The curse of composite endpoints contin-ues to afflict CABG vs. PCI trials. SYNTAX randomised patients with three vessel or left main stem disease to CABG or PCI. There were significantly more adverse cardiac/cerebrovascular events in the PCI arm largely due to more repeat PCIs. It doesn’t really answer the question though if you frame it” What would you rather have, one CABG or two PCIs?”

P Serruys and others N Engl J Med 2009;360:961-72

Some people have been banging on for years about warfarin rather than aspirin for heart failure patients without another

anticoagulation indication. The rationale is that aspirin may make heart failure worse by it’s NSAID action and poor LV function is a recognised risk factor for cerebrovascular events. In a study of 1587 patients in sinus rhythm with heart failure randomised to aspirin, clopidog-rel or warfarin there was no difference in a cardiovascular composite endpoint despite modest reductions in stroke and heart failure exacerbations in the warfa-rin group.

B Massie and others Circulation. 2009;119:1616-1624

Catheter radiofrequency ablation of renal sympathetic inputs is effective in reduc-ing mean blood pressure over one years follow up in a proof of concept trial of fifty patients. The technique appears safe and moderately effective.

H Krum and others The Lancet, 2009 373; 9671:1275–1281

Opening blocked arteries is a satisfying activity but once an infarct has com-pleted does it offer any benefit to the patient? Not according to a study of nearly a thousand patients with com-pleted infarcts, a battery of quality of life measures demonstrated no advantage but a considerable cost disadvantage when opening the artery was compared with medical therapy.

D Mark and others, N Engl J Med 2009 360:774-783

I previously reported on descriptions of the newly recognised sudden death-causing early repolarisation syndrome. Effective drug treatment for this con-dition has now been described with Isoprenalin (acutely) and Quinidine (for maintenance). Beta blockers, amiodar-one, verapamil and Class 1C agents were all ineffective.

M Haissaguerre and others J Am Coll Cardiol, 2009; 53:612-619

Risk stratification of hypertrophic car-diomyopathy lacks the randomised, ICD intervention evidence base of ischaemic heart disease. One of the risk factors used is syncope and a study of over 1500 patients supports this interpretation with recent unexplained syncope associated with a five fold increase in sudden cardiac death. More temporally remote episodes were weaker predictors and neurally mediated (as judged clinically) episodes were not predictive.

P Spirito and others Circulation. 2009;119:1703-1710

Arrhythmogenic right ventricular dyspla-sia (cardiomyopathy) is increasingly in-vestigated by MRI. Results can be difficult to interpret with a matrix of clinical and radiological major and minor criteria ap-plied. A novel radiological finding dubbed the “ accordion sign,” due to the appar-ent crinkling of the outflow tract and peritricusopid myocardium, appears to have a high specificity for the condition.

D Dalal and others J Am Coll Cardiol, 2009; 53:1289-1299

What is the point of putting in a device which needs to pace over 90% of the time to benefit the patient and then allowing the patient’s own rhythm to suppress therapy? Not much, but an excellent study of Holters in resynchro-nisation recipients with atrial fibrillation has clearly demonstrated much higher rates of intrinsic rhythm and fusion than the device counters would suggest. A useful reminder that CRT recipients with AF must have adequate rate control achieved.

G Kamath and others J Am Coll Cardiol, 2009; 53:1050-1055

Dr John PaiseyConsultant Cardiologist and

ElectrophysiologistRoyal Bournemouth Hospital

Journal Trawl- Dr John Paisey scans the world’s cardiology journals

Insert Title

ECG CHALLENGE


See for

yourself at

Heart Rhythm 2009

at the Philips and

Bard booths

www.philips.comwww.bardep.comwww.bardep.comwww.bardep.com

Learn more about our collaboration.

Visit us at Heart Rhythm 2009 in Boston.

Working together, advancing EP, helping people.

34ELECTROPHYSIOLOGY

Bard is a registered trademark of C. R. Bard, Inc. or an affiliate. Bard is a registered trademark of C. R. Bard, Inc. or an affiliate.

All other trademarks or registered trademarks are the property of their respective owners. ©2009 C. R. Bard, Inc. All rights reserved. LT04Z0387/Rev.0/04-2009All other trademarks or registered trademarks are the property of their respective owners. ©2009 C. R. Bard, Inc. All rights reserved. LT04Z0387/Rev.0/04-2009

History: ECG from a pati ent with a dual chamber permanent pacemaker, 24 hrs post implant. Leads implanted in conventi onal RA and RVA locati ons.

Question: What is the explanati on for this ECG appearance?

Answer: See page: 28

Ian Wright’s ECG Challenge

EDUCATION

A Synergistic Approach to Clinical Education

St. Jude Medical understands that today’s clinicians are seeking solutions to deal with an increasingly broad spectrum

of cardiac rhythm disorders and co-morbidities. Because electrophysiologists (EPs) don’t treat patients separately for Atrial Fibrillation (AF) or Cardiac Rhythm Management (CRM) related conditions, St. Jude Medical has focused its energy on providing practitioners with products and training to treat the full range of EP related issues. With this unique synergy of treatments for both AF and CRM, St. Jude Medical has positioned itself apart from its competitors by providing education that targets complex topics on therapy delivery and disease management, which may have otherwise been segregated along business lines.

In the United Kingdom, St. Jude Medical will conduct over 40 unique courses and will target 500 delegates in 2009. Course offerings include those for physicians as well as those for allied professionals and focus on topics that range from cardiac pacing to non-contact mapping to IBHRE exam preparation. Highly-trained specialists offer therapy-based courses focusing on complex disease states such as atrial fibrillation and heart failure and on cutting-edge topics such as remote disease management.

Flexibility is the hallmark of the St. Jude Medical education program. Not only is the program flexible enough to accommodate a variety of learning styles and experience levels, but locations can be found throughout the UK and Europe. Whether delegates prefer to attend courses at the UK Learning Centre at Stratford-Upon-Avon or the new St Jude Medical Advanced Learning Centre in Brussels, Belgium, course participants gain first-hand experience in the use of advanced medical technology through innovative training tools.

- Behind the Scenes at St. Jude Medical UK

Above: Lynne Howell, St Jude Medical Low Voltage Educator instructs on advanced algorithms and troubleshooting in the Larsson Training Room.

Above: Karen Zega, AF Education Manager discusses 3D mapping with clinicians, Abigail Butler, Royal Bournemouth Hospital, Jennifer Cole and Angela Griffiths, John

Radcliffe Hospital in the Waller Room for Advanced EP.


EDUCATION

The new St. Jude Medical Advanced Learning Center in Brussels is equipped with virtual reality simulators that enable physicians to hone their skills in lead implantation and will soon enable simulation of advanced ablation and transseptal procedures. A cardiac rhythm simulator allows physicians and cardiac physiologists to develop skills in programming pacemakers, ICDs and CRT devices.

Specialists and opinion leaders augment St. Jude Medical’s core teaching faculty with real world experience and practice-changing insights. Partnerships with these clinicians are also helping St. Jude Medical to expand course offerings into complex areas like AF ablation in patients

implanted with devices and patients with heart failure.

The goal of St. Jude Medical’s education program is to help clinicians develop new skills allowing them to deliver optimal patient outcomes in a way that reduces risk and increases control. Cross-divisional synergies enhance that mission through a diverse course offering promoting best practice therapy for complex cardiac rhythm disorders and co-morbidities, advanced training technologies, and customized learning methodologies.

Interested in attending a course?

For more information on the St. Jude Medical educational offerings please contact your St. Jude Medical AF or CRM sales representative.

Below: Karen Zega with clinicians in the Senning Clinical Room and Wet Lab discussing preparation of St Jude Medical’s non-contact mapping balloon.


CONFERENCES


We are pleased to invite you to participate in the British Cardi-ovascular Society’s 87th Annual

Conference and Exhibition. The BCS ACE is the UK’s leading and largest cardiovascu-lar event. With over 2,500 healthcare pro-fessionals attending across the 3 days and over 100 industry partners, it is the most highly attended and respected cardiovas-cular event in the UK.

2009 sees the BCS Annual Conference and Exhibition returning to London but to a new venue, the ExCeL Centre in Dock-lands, with excellent conference and hotel facilities. The Conference has evolved over recent years and although its scientific content remains important, it has become much more of an educational meeting. With seventeen Affiliated Groups within the BCS there is a wealth of expertise from all areas of modern cardiology, re-flected in an “action packed” programme this year. Collaboration between Affiliated Groups as well as educating and updating non specialists is one of the strengths of the Conference. There are also key ses-sions with the European Society of Cardi-

ology (ESC) and the American College of Cardiology (ACC) with whom the BCS has a new twinning relationship with the Cali-fornian Chapter of the ACC, reflected in a superb joint session on heart failure.

The Exhibition is an impor-tant part of the Conference and this year it has been further integrated into the programme with edu-cational activities occur-ring in the Exhibition area throughout the meeting. The ever popular simula-tors have been extended to include electrophysiol-ogy this year and look out for the new “Meet the Ex-perts” dotted around the Exhibition Hall providing “snapshots” of good clini-cal advice in interesting or

difficult areas of clinical practice. On the Wednesday of this three day meeting, there will be a focus on Cardiac Rhythm Management to attract delegates inter-ested in this area who might only be able to attend for a day. If it is not your scene, don’t worry, there will be plenty of other subspecialty areas throughout the day.

Dr Iain SimpsonVice President Education and Research, BCS

PROGRAMME OVERVIEW

As well as a wide variation of How To sessions, case presentations, moderated posters and sub-specialty lectures from Affiliated Groups of the BCS, below are some of this year’s highlight talks. They are included to give you a flavour of the conference content; for a full outline of the programme visit the conference sec-tion of the BCS website, www.bcs.com.

2009 British Cardiovascular Society Annual Conference And Exhibition Preview

BCS ANNUAL CONFERENCE AND EXHIBITION, 1 TO 3 JUNE 2009

TO BOOK YOUR PLACE, GO TO OUR ONLINE REGISTRATION AT WWW.BCS.COM

HELD AT EXCEL, LONDON - WWW.EXCEL-LONDON.CO.UK

HOTEL AND VENUE INFORMATION CAN BE FOUND IN OUR CONFERENCE SECTION OF THE WEBSITE.

Above: PCI Simulator

CONFERENCES


Monday 1 June

Trainee Day including a session with the Specialty Advisory Committee in Cardiology.

Revalidation in Cardiology: where are we and where are we going? Chaired by Prof Keith Fox and Dr Nicholas Boon the session will cover the Eu-ropean, UK and GMC perspective on this key topic.

This year’s Paul Wood Lecture will be given by Dr Valentin Fuster and is titled Promotion of Cardiovascular Health: From Risk Factors to Imaging and Genomics.

Tuesday 2 June

BCS will join the European Society of Cardiology to give a session on Guidelines and guidance. The session will cover implementation of the ESC Guidelines; the new National Data-base for Endocarditis; Fitness to Fly report; review of the European Endo-carditis Guidance.

BCS plenary on Audit and Clinical Practice, which will include talks on national data collection and the roll-out of PPCI.

BCS and the British Heart Foundation (BHF) have jointly commissioned a report on Inequalities in cardiac care

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in the UK, by the Oxford Health Asso-ciates led by Dr Stephen Green. The findings of the report will be given in this session, followed by panel dis-cussion of the implications.

Joint plenary on Heart Failure by BCS and the American College of Cardiol-ogy, with key talks from Dr Michael Fowler, Prof John McMurray and Dr Barry Greenberg.

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The 2009 BCS Lecture will be given by Prof John Deanfield, and will be titled Investing in your arteries! Lifetime management of atherosclerosis.

Wednesday 3 June

This years’ Strickland Goodall Lecture will be given by Prof David Newby and will be titled, Intravascular throm-bosis: new frontiers in endothelial function

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Don’t forget to stop by the Coronary Heart Publishing stand at Booth 286, towards the back near the simulators. Our Director, Tim Larner would love to meet you.

Above: Lecture Audience

Left: Echo Demonstration

CARDIAC MRI

A Simplified Introduction to Cardiac MRI

- Coming to a Cardiology Department near you

Basic Physics:To give you a full understanding of the physics of Magnetic Resonance Imaging (MRI) would require another 100 editions of this publication, so here is a simplified outline on what this complex imaging modality is. The proper name is actually Nuclear Magnetic Resonance Imaging (NMRI), however in the current world that we live in, the word “nuclear” cre-ates a sense of fear, therefore just MRI is used for consumer comfort.

When you first look at a traditional MRI most people think it is just an overly large CT scanner, however the two imaging systems couldn’t be further apart in the function of obtaining diagnostic images. One uses x-rays (CT), whilst the other uses the effect of magnetic fields on the body’s molecules (MRI).

Excite and Relax:

We all know that the human body is comprised primarily of water (H20) with hydrogen atoms making up 63%, with

Mr Tim Larner

Director, Coronary Heart Publishing LtdSenior Cardiac RadiographerManchester Royal Infirmary

Image courtesy Siemens Medical Systems


CARDIAC MRI

all parts of the body containing some of the element. In a normal state outside of a strong magnetic field, the hydrogen protons spin randomly at a constant rate in various directions, however in different tissues they have different concentra-tions. It’s the differences in how they are bound in each type of tissue and the relative concentrations in each tissue that we are measuring.

Components:Primary Magnet:

Looking at the image right the primary magnet is the largest part of system. It is comprised of a large electrical wire which is coiled, with an electrical current passing through. This results in a strong magnetic field created in the centre of the coil. Left without any extra interven-tion the electrical current is subject to resistance, reducing the amount of mag-netic field strength. Therefore the coiled wire is surrounded by liquid helium at -269 degrees Celsius, becoming a super-conducting electromagnet. The magnetic field produced is then 20,000 times the magnetic field of the earth, developing 1.5 to 3 Tesla, the optimum range for medical imaging.

Gradient Magnets:

Referring again to the image right you can see additional smaller magnets called Gradient magnets located closer in to the centre from the primary magnet. There are usually three of these magnets each with a field strength 1/1000th that of the primary magnet. The purpose of

these magnets is to precisely adjust the magnetic field so that specific areas of the body can be imaged.

RF Coil:

When the body is placed inside the MRI the magnetic field forces the hydrogen atoms to spin in one of two directions in-line with the field. When all atoms are aligned a radiofrequency is emitted from the inner coil (RF Coil) which causes the hydrogen atoms to change direction and spin in another direction. This transition causes an energy release as the mole-cules change from their high-energy state to their low-energy state. The absorption of RF energy by the protons, affecting their energy state (not spin direction) is known as resonance. There are different rates of energy loss for different tissues which are displayed as shades of grey.

Confused yet??This is obviously a quick overview of the workings, and there is much more to talk about. At university we learnt how to do the full mathematical problem solvings of Fourier Transforms, a 4 –page extremely advanced mathematical algorithm which are used to determine the individual tissue frequencies and amplitudes of the resonance signal. Consider yourself lucky not to go through that pain!!

Dangers:The biggest danger with MRI’s is the presence of metals either inside the patient as part of a medical procedure or brought in accidently. I heard a story once of a doctor walking in with a pen in their pocket. When they were near the patient the magnetic field pulled at very high speed the pen out of the pocket narrowly missing the head of the patient. There was also a case reported in Aus-tralia in 2000 whereby a patient with a newly inserted pacemaker was given an MRI. Although the staff had twice asked if they had a pacemaker the patient each time stated “No”. The reason the patient said “No”, was most likely caused by confusion and stress. The patient died as a result of their pacemaker malfunction-ing. Systems must be in place to avoid situations like this occurring.

Above: MRI Images sagittal and axial of the heart(images courtesy St Paul’s Hospital, Vancouver)

The MRI diagram above can be found at: http://en.wikipedia.org/wiki/File:Mri_scanner_schematic_labelled.svg

CORONARY HEART ™ 1�

CARDIAC MRI

Contrast Enhancements: Different tissue densities and their proton relaxation times produce the image con-trast differences of an MRI image. How-ever sometimes it is difficult to accurately visualise the differentiation such as in the case of demonstrating an infarction. Gadolinium - DTPA is a paramagnetic compound (attracted to a magnetic field) and is commonly used in cardiac MRI as a contrast agent where it appears very bright in certain tissues.

Advantages:

Visualise structure and function of heart.

Detect and evaluate coronary heart disease

Determine extent of tissue damage and viability post MI / chronic heart disease.

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Can create moving images of the pumping function of the heart dem-onstrating contraction problems and blood flow abnormalities.

Images can be obtained at any angle allowing physicians to easily obtain images of complex anatomy.

Uses:

ischemic heart disease,

myocardial disease,

right ventricular abnormalities,

pericardial disease,

cardiac tumors,

valvular disease,

thoracic aortic disease,

pulmonary artery disease,

congenital heart disease before and after surgical repair.

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Disadvantages:

MR images are obtained through a process called “gating”, whereby the an ECG is used to acquire images at each stage of the cardiac cycle over several heart beats. If a patient has an irregular rhythm this can reduce the image quality.

Patients with metallic objects such as pacemakers are unable to be scanned.

Unlike ultrasound, an MRI is not portable to take to the patient’s bedside.

Gadolinium can be toxic to patients with impaired kidney function, with haemodialysis recommended in some cases.

Future:As with all technology, faster com-puter processors are allowing for real-time MR images. Several new scanners have this capability how-ever the image quality is at present reduced compared with gating.

Some medical device companies are developing MRI safe pacemakers. Medtronic is currently trialing the EnRhythm® MRI SureScan™ pacing system, for this purpose.

Improvements in the development of MRI contrast media agents are oc-curring all the time, such as what has occurred with cardiac angiography.

Bibliography

Cluett, J. M.D. 2006, About.com, MRI – What is MRI? Retrieved 1st August 2008, http://orthopedics.about.com/cs/sportsmedicine/a/mri.htm

http://en.wikipedia.org/wiki/Cardiovascular_magnetic_resonance

http://www.radiologyinfo.org/en/info.cfm?pg=cardiacmr&bhcp=1

http://my.clevelandclinic.org/heart/history/future/mri.aspx

Calvert, J. & Taylor, T., Death Link to Hospital Scan, Retrieved 1st August 2008. http://www.users.on.net/~vision/misc/pacemaker-death.html

http://en.wikipedia.org/wiki/Mri

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A Simplified Introduction to Cardiac MRI (cont...)

Above: MRI Images of the heart(images courtesy GE Healthcare, USA)

1� CORONARY HEART ™

PHARMACY

Ranolazine is a new and unique anti-anginal drug licensed for the man-agement of chronic stable angina

pectoris. It acts as selective inhibitor of late sodium influx, thereby attenuating the abnormalities of ventricular repolari-sation and contractility associated with is-chaemia. Randomised clinical trials have shown the efficacy of the agent in increas-ing exercise testing and reducing anginal episodes and the use of GTN sprays.

MARISA (Monotherapy Assessment of Ranolazine In Stable Angina) trial was a double blind crossover in 191 patients who had angina-limited treadmill tests. They were randomised to ranolazine or placebo. Total exercise duration at trough (at 12 hour) was significantly improved in the ranolazine group (1).

CARISA (Combination Assessment of Ranolazine In Stable Angina) was a dou-ble blind trial of 823 patients with chronic stable angina, already on atenolol, am-lodipine or diltiazem. Patients were as-signed to either ranolazone or placebo for 12 weeks. Ranolazine showed a sig-nificant increase in exercise capacity, time to angina and ECG ischaemia compared to placebo (2).

The ERICA (Efficacy of Ranolazine In Chronic Angina) trial investigated the efficacy in patients with persistent symptoms de-spite optimised therapy with amlodipine. Angina episodes were self-reported dur-ing the 6 week double blind phase in 565 patients randomised to either placebo or ranolazine. The trial showed that on aver-age, there was one fewer angina episode per week in the ranolazine group (3).

MERLIN – TIMI 36 trial investigated the efficacy of ranolazine in 6,560 patients with Acute Coronary Syndrome. Ranola-zine was not associated with a statisti-cally significant decrease in the primary end points of cardiovascular death, myo-cardial infarction or recurrent ischaemia, compared to placebo.Ranolazine’s side effect profile includes dizziness, constipation, nausea and the

potential for prolongation of the QT interval.

Ranolazine may be a useful therapy in pa-tients with chronic angina pectoris who cannot tolerate the initiation or upward titration of anti0anginal drugs. Further clinical trials are needed in order to con-firm its long term safety, its optimal dos-ing, and efficacy in combination with full doses of other anti-anginal therapies

References:

Chaitman BR, Skettino SL, Parker JO, et a, for the MARISA investigators. Anti-ischaemic ef-fects and long term survival during ranolazine monotherapy in patients with chronic severe angina. J Am Coll Cardiol 2004; 43: 1375-82.

Chaiman BR, Pepine CJ, Parker JO et al, for the CARISA (Combination Assessment of Ranolazine in Stable Angina) investigators. Ef-fects of ranolazine with atenolol, amlodipine, or diltiazem on exercise tolerance and angina frequesncy in patients with severe chronic angina. A randomised controlled trial. JAMA 2004; 291: 309-16.

Stone PH, Gratsiansky NA, Blokhin A et al, for the ERICA investigators. Anti-anginal effects or ranolazine when added to treatment with amlodipine: The ERICA (efficacy of Ranolazine in Chronic Angina) trial. J Am Coll Cardiol 2006; 48: 566-75.

Morrow DA, Scirica BM, Karwatowska-Proko-pczuk E et al for the MERLIN-TIMI 36 trial investigators. Effects of ranolazine on recur-rent cardiovascular events in patients with non ST elevation acute coronary syndromes. The MERLIN-TIMI 36 randomised trial. JAMA 2007; 297: 1775-83.

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Drug Focus- Ranolazine for Chronic Angina Pectoris

CCO National Conference

Cardiovascular

Therapeutic Update 2009

26th & 27th November 2009,

Central London

Further information and enquiries

via e mail [email protected] or [email protected]

Provisional Programme:

Hypertension and stroke prevention.

Cholesterol lowering and Cardiovascular Disease.

New evidence in cardiovascular medicine: Hot Topics from International Cardiology Conferences.

Acute Coronary Syndrome Update: Prepare for NICE Guidelines.

Heart Failure management: An Update

Preventive Cardiology: Delivering evidence based cardiovascular prevention

Diabetes as a cardiovascular risk factor: new therapeutic targets.

Focus sessions on Guidelines from NICE, ESC, ACC & AHA

Vascular Risk Assessments: Where are we now?

Update from Heart Improvement Programme and Cardiovascular Networks.

Thrombosis: Evolving therapies

Other clinical networking sessions and guidelines TBC

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The two-day event presents an excellent educational opportunity to update and extend knowledge, focusing on the major elements of cardiovascular disease management. The conference will also provide an excellent arena to discuss the latest developments and practical managements of cardiovascular disease. Early registration will attract a discount.

Dr Mojgan H Sani, DPharm, MBA, MRPharmSHead of Clinical Pharmacy

Royal Berkshire NHS Foundation Trust


SITE VISIT

Liverpool Heart & Chest Hospital NHS Trust

The Liverpool Heart and Chest Hospital NHS TrustThomas DriveLiverpoolL14 3PE

Largest single cardiac specialist centre in the UK.

Perform cardiac, thoracic, and abdominal procedures.

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Departmental questi ons have been answered by Teresa Darmody, Acti ng Cath Lab Manager.

What is size of your Cath Lab facility / Hospital?

Liverpool Heart and Chest is the largest single centre specialist cardiac centre in the UK. The Trust services a populati on of 2.8 million covering Merseyside, Cheshire, West Lancashire, North Wales and the Isle of Man. The centre also serves as a nati onal referral unit for a range of specialised cardiac and thoracic procedures. The EP service is also one of the largest in the UK. We have 6 cardiac catheterisati on labs – 4 of which are used for PCI (3 x bi plane) and 2 are dedicated

EP labs with in-build EP systems. We also have two pacing faciliti es including a hybrid theatre where Percutaneous aorti c valve and aorti c stent procedures are performed. Aorti c stenti ng is performed electi vely in the treatment of aorti c aneurysm and coarctati on.

Our procedures involve the thorax, however abdominal/ iliac stenti ng is also performed combined with CABG.Stenti ng may be performed as an emergency, following acute aorti c dissecti on or leaking aneurysms, pati ents have come from as far away as Birmingham.

How many staff ? Roles?

The team compromises of the usual

disciplines of cardiac physiologists, radiographers, registered nurses, health care assistants, transfer staff , a stock team and medics.

The nursing team is comprised of 3 teams – 22 nursing staff , 3 stock members and 5 transfer staff .

The cardiac physiologists have a team of 20. They also cover 2 pacing theatres, one pacing and one ICD clinic daily, epicardial implants and PAVI cases in theatres, echo and a wide range of other non invasive services.

The radiographers have a team of 13 full and part ti me staff , also covering the hybrid theatre where pacing, aorti c

Fast Facts

From Left: patient, EP consultant Dr Mark Hall and Radiographer Randhir Sadankar


SITE VISIT

stenting and percutaneous aortic valve replacements are undertaken. Their rotation to the main department also involves general radiography or CT scanning.

We stick to fairly traditional roles although we have a member who recently finished the assistant practitioner course and we are looking at a role being one involving cross training to some degree.

Types of procedures:

We essentially divide into EP and interventional coronary procedures.These include Angiograms, PCI, Alcohol Septal Ablation, PFO/ASD closures and valvuloplasty.

We perform ablation for AVRT, AVNRT, A. Flutter, A. Tach, PVI and ablation for Ischemic and idiopathic VT.

In the hybrid theatre, Percutaneous Aortic Valve Replacements have recently been introduced for patients not suitable for surgery, with calcific aortic valve disease

Equipment:

Xray equipment is all Philips. 2 bi-plane Allura 10-10 flat plate systems with rotational angiography capability and stent boost.

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2 single plane Allura flat plate detector systems set up for EP procedures with low dose and low frame rate fluoroscopy capabilities.

1 Integris biplane conventional lab for PCI and a single plane Integris situated adjacent to the day ward suitable for diagnostic lists.

The hybrid theatre is an Allura FD 20 with rotational capabilities, subtracted angiography and smart mask.

We have two mobile Pulsara image intensifiers with cardiac capabilities and low dose fluoroscopy designed for long screening times often required for BiVentricular pacing.

Standard assessment and diagnostic tools of IVUS (Volcano) and RADI and Volcano pressure wire. We utilise the rotablator and laser also.

EP has 2 integrated EP labs each fitted with a Bard EP system, Carto system and Navix system.

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From Left: patient and registrar Dr Scott Murray

From Left: behind screen Cardiac Technician Tony Fern, Registered Nurse Zia Ur-Rehman, Cardiology Consultant Dr Nick Palmer ( behind

screen), HCA Sylvia Shaw and Registrar Scott Murray.


SITE VISIT


Liverpool Heart and Chest Hospital (cont...)

Procedures performed per year:

In 2008 we did roughly

1584 angiograms

2335 PCI

870 EP studies with predication of 1000 this year.

1200 Pacing and ICD procedures

55 PFO/ASD closures.

Cross-training of staff:

The “generic” cath lab worker is something we have put a lot of thought into but not yet realised. A suitable course with accreditation in the local area is required.

New procedures implemented:

On the 26th of Jan 2009 we commenced phase one of our PPCI service. We are still refining our delivery and to date it is going well thanks to such thorough planning involving people such as the cardiac network, the North West Ambulance Service, all participating hospitals, CCU and all supporting departments, the Cath Lab Manager Karen Wafer, and the consultants Dr Perry and Dr Mills who put in a lot of time doing face to face education. It also involved a dedication for this to work from all the cath lab staff as the target times put a lot of additional pressure on the team as some live more than 30 mins drive away. We currently work on an ONCALL basis for PPCI out of hours and not shifts.

The second new procedures we are involved in are the Percutaneous AO valve replacements, from the trans apical and femoral approach as considered appropriate.

Inventory Management:

Our stock comprises mostly of stock that we own and some consignment. We Re-order using the Oracle Stock Management System and NHS logistics forstock items. We are looking to move to a fully computerised stock management

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system that records every item used in the near future.

Haemostasis Management:

The majority of our interventional procedures are done radially with only 2 of our 7 PCI consultants preferring to take the femoral approach. EP by its nature predominantly requires only venous punctures, be that femorally and /or via the subclavian approach.

Therefore we use a range of techniques for haemostasis depending on approach, patient attributes and operator preference which may take in factors such as the need to keep the approach free from complication for future use such as a planned IABP insertion.The main devices used are the Terumo TR Band available in 2 sizes and the angioseal. We also use compression devices such as the Radistop and the Femstop. Measures implemented to cut costs:

We always look at competitive prices when buying. Bulk items go out to

tender. We aim to minimise stock held in each lab to promote stock rotation and efficient use of resources.

Recently we purchased the ACIST device in order to minimise contrast use and reduce the amount of wasted and disposed of contrast.

Training for new employees:

For the nursing staff in an ideal world they would get 6 weeks supernumerary where they work with a dedicated mentor and complete competencies. In this time they aim to learn roughly how the department functions and the circulating role. This will be built on later by learning the scrub role competencies and eventually Oncall.

For the cardiac Physiologists the training is very similar. They will have a period of time spent in the lab with a mentor (varies depending on their length of experience and type of work the individual performed at their previous centre). At the end of this period they will then complete in-house competencies.

From Left: Cardiac Technician Tony Fern, RN Zia Ur-Rehman, patient, Cardiology Consultant Nick Palmer, Registrar Scott Murray and head of Sylvia Shaw HCA

SITE VISIT


For Radiographers, Induction training for new staff, additional training for new equipment eg the ACIST New techniques PAVI, aortic stenting, rotational angiography and Radiation protection refreshers. In house audit days, quality groups, cardiology lunch time meetings, chest imaging talks. Also external cardiac courses

Continuing education programs available to staff:

There are opportunities for conferences and study days. Also programs to maintain proficiencies such as ILS/ALS. Kinds of competency checks staff have to undergo once employed:

Not all nursing staff scrub or goes oncall. We are currently working on competencies where each nurse will learn in 3 parts – first the circulating, then scrub and oncall simultaneously depending on the staff members individual progress and Banding. It is not a requirement for ONCALL to scrub as there is routinely a SpR to assist the consultant.

There is the standard yearly mandatory training and we have monthly audit pm’s where training is scheduled involving outside speakers from companies.

Department Management structure:

The department is headed by the Cath Lab Manager who works alongside the technical lead for Cath lab / EPEP and Head of Radiography. Below each discipline is the standard Banding structure. On the medical side the department has a clinical lead for the Labs which is Dr Rod Stables.

Dealing with late finishing of cases:

This is a problem that arises no matter where you work. Wherever rules are put in place they are always tested to the limit as you want to get the most out of the service and sometimes you just can’t foresee the length of time a procedure may take. There are set session times for the labs and the nursing staff are

rostered to start prior to and after the completion of these sessions. The cardiac physiologists and Radiographers differ in there hours so at times when multiple labs overrun this presents an issue. We can run one on after hours as that becomes the ONCALL team.

Policy for company reps within the labs:

All visitors must sign in and out. They book in advance with a consultant and on their lab visits they are not to introduce

new products as they are required to book separate appointments to introduce these thereby relieving some pressure on the consultant when they are working in the lab.

What is the best part of working at your facility?

With the large volume of acute work we do you get to see a wide spectrum of cases including more unusual presentations that in a smaller department you may never witness.

EP cardiac technician Neil Ness and EP Consultant Mark Hall.

EP EDUCATION


Firstly there is disagreement about how the term atrial tachycardia should be used. A strict defi ni-ti on would be all fast rhythms

which originate in the atria and that not require other ti ssue to sustain. This would of course include typical atrial fl utt er and atrial fi brillati on (AF). We can exclude AF however as atrial tachycardias must be (fairly) regular.

Focal verses re-entrant mechanisms

In practi ce electrophysiologists tend to use this term to refer to focal atrial tachycar-dias. Re-entrant tachycardias are referred to as macro re-entrant atrial tachycardia or atrial fl utt ers. Someti mes disti ncti on between focal and re-entrant cannot be made on the basis of the surface ECG, par-ti cularly if there is atrial disease or previ-ous surgery/ablati on. For example both focal and re-entrant atrial tachycardias are reported as a complicati on aft er AF ablati on and in these pati ents a diagnosis of the underlying mechanism may only be possible at an EP study.

A focal tachycardia originates from a point source with acti vati on spreading concen-trically to acti vate surrounding ti ssue. The rate of fi ring of the focus drives the tachycardia rate – sinus tachycardia for example is a focal atrial tachycardia. In contrast re-entrant rhythms occur due to the existence of an “endless loop” of acti vati on with an impulse travelling in a circuit formed by obstacles to conducti on

– an analogy is a Mexican wave. The ti me taken for one revoluti on of the circuit (the cycle length) determines the rate of tachy-cardia. Focal tachycardias are ablated by identi fying the site of earliest acti vati on - in atrial tachycardias this occurs before the onset of the p wave on the surface ECG. Re-entrant tachycardias are ablated by defi ning the tachycardia circuit and ab-lati ng a criti cal isthmus (narrow region) of slow conducti on without which the circuit cannot sustain.

In focal tachycardias there is oft en (but not always) an iso-electric baseline be-tween p waves, as is seen in sinus tachy-cardia. If this is evident in all 12 leads the rhythm is likely to be focal. Unfortunately the preceding T wave can interfere with this determinati on during one to one con-ducti on. An iso-electric interval occurs be-cause atrial acti vati on occurs in a shorter period of ti me than the tachycardia cycle

length, leaving an interlude between the latest atrial acti vati on and the next depo-larisati on of the focus. However, where there is slow atrial conducti on away from the focus and/or the tachycardia is par-ti cularly rapid the iso-electric line can be absent. In macro re-entrant atrial tachy-cardia (atrial fl utt ers) there must be con-ti nuous acti vati on in the re-entrant circuit from one cycle to the next (see fi g 4). This manifests as “fl utt er” or “f” waves on the surface ECG rather than disti nct p waves. Re-entrant atrial rhythms occur in pati ents with atrial pathology, previous atrial sur-gery or extensive ablati on for AF.

At EP study mode of initi ati on and termi-nati on, reliance on isoprenaline for induc-ti on, warm-up/cool down and responses to entrainment contribute to an under-standing of the mechanism, which is criti -cal for the adopti on of an appropriate ab-lati on strategy.

Atrial Tachycardia

Sponsored by:

Fig 1: Atrial tachycardia with 2 to 1 A-V conduction (p waves are indicated in lead one). This could easily be mistaken for sinus rhythm.

There are discrete p waves with an iso-electric interval. The p wave axis is very similar to sinus rhythm as this is a high crista tachycardia – i.e. from

a region close to the sino atrial node.

Ian Wright, Technical Head EP, St Mary’s Hospital,Imperial College Healthcare NHS Trust, London, UK

EP EDUCATION


Fig 2: Focal crista tachycardia. Shaded areas contain no atrial signals corresponding to the iso-electric interval on the surface ECG, suggesting a focal mechanism. Care must be taken to ensure that signals spanning this interval have not been missed.

Fig 3: Macro re-entrant (incisional) right atrial tachycardia – no clear iso-electric period

EP EDUCATION Sponsored by:

Fig 4: Intra-cardiac signals in macro re-entrant atrial tachycardia. There is continuous activity from cycle to cycle (between vertical lines). A long fractionated signal on

the ablation catheter (Mapd) spans the time between two groupings of atrial electrograms. Such signals characterise a slowly conducting critical isthmus in a re-

entrant circuit – ablation at this site terminated tachycardia.

Atrial Tachycardia (cont...)

3D mapping technology

Patients with multiple tachycardias or complex re-entry present challenges for conventional mapping techniques. This map shows electrical voltage and abla-tion points superimposed on a CT scan of the left atrium in a patient with mitral valve replacement and previous epicar-dial surgical Maze procedure. The ability to view the anatomy in three dimen-sions, record ablation points, identify re-gions of scar tissue and follow wave-front propagation facilitated ablation of five atrial tachycardias in this patient. In this view there is a cluster of pink ablation points which terminated one tachycar-dia. Green dots show PV encirclement. Fig 5: 3D left atrial (LA) map (Ensite NavX, St. Jude Medical).

EP EDUCATION

Diagnosis

In the absence of bundle branch block or an accessory pathway atrial tachycardias present as a regular narrow complex tach-ycardia. The differential diagnosis is AV nodal re-entrant tachycardia (AVNRT), A-V re-entrant tachycardia (AVRT) atrial tachy-cardia or atrial flutter. Atrial tachycardia can sustain without the participation of the ventricles or the AV node. The diag-nosis is therefore self evident where there is a high degree of A-V block (see fig 4). When atrial tachycardias are conducted to the ventricle in a one to one relationship the diagnosis may be more difficult. Ad-enosine can be used to induce transient high grade AV block – if the tachycardia can sustain despite loss of AV conduc-tion it is atrial tachycardia. Unfortunately some atrial tachycardias are terminated by adenosine (adenosine sensitive) and so termination, though suggesting AV nodal involvement in a circuit (i.e. AVNRT, AVRT) cannot rule out atrial tachycardia.

In some cases the p wave morphology can be seen to be inconsistent with retro-grade atrial activation. In AVNRT and AVRT the atrial activation must be retrograde –it must begin somewhere on the A-V ring. A p wave axis or intra-cardiac signal sequence not consistent with retrograde atrial activation strongly supports a diag-nosis of atrial tachycardia. This is seen in figures 1 and 2 showing tachycardia from the superior crista terminalis. The p wave is similar to a sinus p wave with activation from superior to inferior (“high to low”). On the intracardiac signals the high right atrial (HRA) signal is much earlier than the annular signals (CS and His catheter) – inconsistent with retrograde activation. When the atrial sequence is consistent with retrograde activation, particularly when compatible with atypical AVNRT, the diagnosis is more difficult.

Pacing manoeuvres can be used to facili-tate a diagnosis. One technique involves entraining the tachycardia from the ven-tricle and observing the A-V relationship on cessation of pacing (see fig 7) An A-A-V response (in contrast to an A-V response) upon cessation of ventricular pacing as-

Fig. �. Focal left atrial tachycardia with one to one conduction

Fig. 7. Simulated A-A-V response during sinus rhythm. Sinus rhythm is a focal atrial rhythm. By pacing the ventricle faster than the sinus rate the ventricular pacing has entrained the sinus node. When pacing is stopped there is a retrogradely conducted atrial event (A). In AVRT or AVNRT the next event would be ventricular (V) – an A-V response. In atrial tachycardia the next event is atrial (the next depolarisation of the

focus – in this case the SA node) which is then conducted to the ventricle – giving an A-A-V response.

CORONARY HEART ™ 2�

EP EDUCATION Sponsored by:

sociated with 1:1 ventriculo-atrial con-duction is highly sensitive and specific for distinguishing atrial tachycardia.

Focal atrial tachycardia

Focal atrial tachycardia (AT) is a relatively uncommon form of supra-ventricular tachycardia (10%) often in the absence of structural heart disease. It is usually located to one of a number of specific anatomical “hot spots”. The pulmonary veins have received an enormous amount of publicity in recent years due to their importance in atrial fibrillation. However, 75% of patients presenting for ablation of regular focal atrial tachycardias (in pa-tients who have not had previous AF abla-tion) have a right atrial source. The crista terminalis accounts for some 60% of right atrial tachycardias whilst the pulmonary veins are the site of origin of half of all left atrial tachycardias. The cellular mecha-nism underlying focal atrial tachycardias is abnormal automaticity or triggered ac-tivity. Automatic tachycardias may exhibit “warm up” and “cool down” behaviour on initiation and termination.

Ablation of focal atrial tachycardia

Ablation is achieved by targeting sites of earliest atrial activation that precede the p wave during tachycardia (see fig 8). Potential complications are related to the anatomical location of the focus. The crista terminalis is close to the sinus node and the phrenic nerve, so there is a po-tential for damage to these structures. Si-nus node damage is rare but its location can be mapped used 3D mapping systems and the timing of the ablation electro-gram should not be the earliest record-able signal in sinus rhythm. Proximity to the phrenic nerve can be checked phrenic nerve stimulation by high output pacing from the ablation catheter. There is a risk AV block complicating ablation of Triangle of Koch foci due to their proximity to the AV node. Cryoablation may be used to maximise safety. Left atrial locations ne-cessitate transeptal puncture with its as-sociated risks.

Atrial Tachycardia (cont...)

Right atrial focus Left Atrial Focus

Crista terminalis Pulmonary veins

Tricuspid annulus Superior mitral annulus

Coronary sinus (CS) ostium Left atrial appendage

Perinodal tissue (Triangle of Koch) CS body

Right side of inter-atrial septum Left side of septum

Right atrial appendage

Table 1. Common sites for focal atrial tachycardias (in order of frequency of occurrence).

Fig �. Signal at successful ablation site for mid crista tachycardia. There are two components on the ablation catheter (Mapd) as it is sitting on the crista which forms a line of conduction delay or block. The small first component is

much earlier than the atrial signal on the other catheters and was the earliest that could be found during extensive mapping. Timing with respect to p wave onset is problematic due to masking by the T wave. The site was confirmed

as the focal origin as application of radio frequency energy terminated tachycardia (fig 9).


EP EDUCATION


Fig. 9. Termination with ablation

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ST. JUDE MEDICAL, the nine-squares symbol and MORE CONTROL. LESS RISK. are trademarks and service marks of St. Jude Medical, Inc. and its related companies. ©2009 St. Jude Medical. All Rights Reserved.

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References/further reading

Kistler PM, Roberts-Thomson KC, Haqqani HM, Fynn SP, Singarayar S, Vohra JK, Morton JB, Sparks PB, Kalman JMP-Wave Morphology in Focal Atrial Tachycardia: Development of an Algorithm to Predict the Anatomic Site of OriginJournal of the American College of Cardiology Vol. 48, No. 5, 2006

Knight BP, Adam Zivin A, Souza J, Flemming M, Pelosi F, Goyal R, Ching Man K, Strickberger A, Morady F A Technique for the Rapid Diagnosis of Atrial Tachycardia in the Electrophysiology LaboratoryJournal of the American College of Cardiology Vol. 33, No. 3, 1999


ECG ANSWER

ECG Challenge Answer

The ECG shows a board complex rhythm at around 60 bpm. Beats 1,2,3,5,6,7 and 9 have a consistent

morphology and the QRS is immediately preceded by a pacing spike. There appears to be a second pacing spike in the middle of these QRS complexes which have a left bundle branch block (LBBB) morphology. They are markedly positi ve in the inferior leads, all consistent with an origin near the right ventricle outf low tract (RVOT).

Beats 4 and 8 are quite diff erent with a more normal dual chamber pacing ap-pearance. We see what appears to be an atrial pacing spike followed by an AV delay and then a ventricular pacing spike that evokes a response. The initi al pacing spike does not capture the ventricle on

these beats. The QRS morphology here is more consistent with conventi onal right ventricular apex pacing (negati ve in II and aVF). On inspecti on of the ECG baseline between atrial spike and QRS on these two beats there does not appear to be a sti m-ulated p wave – it appears that the atrial sti mulus has not captured the atrium. The ventricular output now captures as the ventricle is available for excitati on.

This appearance is consistent with a system where the right atrial lead has prolapsed into the ventricle and is inter-mitt ently capturing the ventricular myo-cardium (in this case probably near the RVOT).

What is interesti ng is the diff erence in interval between the two sets of pacing spikes. On beats 1,2,3,5,6,7 and 9 (RVOT morphology) the interval between the two pacing spikes is about 3 small squares, or around 120ms. On beats 2 and 4 the in-terval is considerably longer – perhaps 4.5 small squares or 180ms. Why should the paced AV delay change like this?

Cross-talk inhibiti on

In some early pacemakers a potenti ally catastrophic interacti on between atrial pacing and ventricular pacing occurred – the ventricular channel sensed the “tail end” of the atrial pacing pulse (beyond the cross chamber blanking period). Hence the atrial output inhibited ventricular pac-ing – a conditi on known as cross talk inhi-

biti on. This leads to persistent inhibiti on of ventricular pacing resulti ng in pati ents with no AV conducti on having only paced p waves! To prevent this from happening device manufacturers introduced a ti ming window during the fi rst part of the AV de-lay immediately aft er atrial blanking. Dur-ing this interval ventricular sensing does not inhibit the impending pacing pulse, which is delivered to the ventricle regard-less, at the end of the AV delay (this is known as committ ed pacing). A drawback of committ ed pacing is the possibility of sti mulati on during the ventricular vulner-able period if the sensed R wave is in fact real rather than artefact (see below).

Inducti on of VT facilitated by R on T pac-ing in a pati ent with an ICD without safety pacing. A ventricular ectopic occurs during the AV delay but does not inhibit the sub-sequent ventricular impulse. Because the programmed AV delay is long the pacing impulse falls outside the refractory period and captures the ventricle. Unfortunately this short coupled beat induces VT.

Safety pacing

One neat soluti on is to deliver committ ed pacing but to force a short AV delay so that the paced beat falls too soon to cap-ture the ventricle - in case the signal is not artefact. This is safety pacing. A commonly used safety pacing AV delay is 110ms – the precise AV delay in this example. Where the atrial sti mulus has captured the ven-tricle the resulti ng signal has been sensed

during the ven-tricular safety pacing window, resulti ng in a contracti on of the AV delay. The programmed AV delay (around 180ms) can be seen in the beats where the atrial sti mulus fails to capture the ven-tricle (beats 2 and 4).

Ian Wright, Technical Head EP, St Mary’s Hospital,Imperial College Healthcare NHS Trust, London, UK

Answer: The atrial lead had migrated into the ventricle.

Refer to Question on Page 9


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Advertisers’ Index:

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09 Bard EPwww.bardep.com

22-27 St Jude Medicalwww.sjm.com

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30 Mediplacementswww.mediplacements.com

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32 British Cardiac Societywww.bcs.com


Next Issue Guide:

Events Diary:May 19-22EuroPCR 2009Barcelona, SpainVisit: www.europcr.com

June 1-3BCS Annual Conference and Exhibition 2009London, ExCeLVisit: www.bcs.com

October 5-65th Sheffi eld Practical Cath Lab CourseMedical Education Centre, Northern General Hospital, Herries Road, Sheffi eld S5 7AUVisit: www.angioed.com

October 18-21Heart Rhythm Congress 2009Hilton Birmingham Metropole, BirminghamVisit: www.heartrhythmcongress.com

26-27 NovemberCCO National ConferenceCentral LondonEmail: [email protected]

Edition 19 (July/August)

Echocardiography

Interesting Case Studies

Invasive CardiologyHot Topic:

- Complex strategies for treating bifurcations with comments from Prof Adam Timmis and Dr Rod Stables.

Can Cardiac CT improve your practice? - A Case study from the BMI London Independent Hospital.

Cardiology Underworld: - Opening up your doors to after hours animal cases.

Management

The evolution of Cardiac MRI

Your experience with hybrid labs for PCI.

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Like to advertise or submit articles? See page 3


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Medical Recruitment

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Specialists in Cardiology and RadiographyCall now to register your interest if you

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RECRUITMENT

Your World Medical Recruitment News

Your World brings a fresh approach to Medical Recruit-ment. We want to be the agency that you come to for your temporary and permanent staffing by supplying you with the best service. We have brought together a

host of experienced consultants that all have genuine knowl-edge in their specialist medical field and will supply you with an honest and reliable service just when you need it.

We have over 15 years experience in Cardiology and Radiogra-phy recruitment and have developed many long term working relationships with clients and candidates built on trust, under-standing, reliability and delivery.

If you are a professional looking to join a professional agency that’s doing all the right things then please register online at www.yourworldmedical.com or browse our current positions available in the UK and Southern Hemisphere.

If you are looking for staff you can submit a vacancy online at www.yourworldmedical.com and your consultant will contact you upon receipt of this to discuss your requirements. Alterna-tively you can request a call back simply request information

if you are considering using our services for temporary or per-manent staff in the future.

Your World invest time and energy in the correct way and stick rigidly to a thorough vetting procedure ensuring the highest quality standards. We offer the very best support to our candi-dates by ensuring they have the tools required to assist them to do the job they are employed to do. We also make a big effort to listen to our candidates thus ensuring their require-ments match your needs.

For further information on working with us please call the team on 020 7426 6999 or visit our website www.yourworldmedical.com.

We look forward to hearing from you!

From Basic Science to Bedside

BCS Annual Conference and Exhibition 2009Venue: London, ExCeL Date: 1 to 3 June 2009

Members of the British Cardiovascular Society

can register for free before 31 March 2009.

For registration or details on how you can

become a member of the Society please

go to www.bcs.com.

3 Day meeting of educational and scientifi c interest in Cardiovascular Medicine

International Keynote Lectures including Dr Valentin Fuster

Educational content based on the new European Curriculum

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Coronary Heart #18

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