Leeds Nuffield Hospital

Leeds Nuffield Hospital – November 2006 www.johnperrins.com

Case Studies in CardiologyOver-Active Implantable Devices!!

Dr John Perrins MD FRCP FACC

Consultant Cardiologist – Leeds UKMember Committee of Safety of

Devices


Case Studies

An angioplasty balloon which gets stuck inside a heart artery

A Pacemaker lead which stabs the patient through the heart


83

87

PCI centres

Angiography onlyCentres

UK PCI CENTRES 2005


PCI vs Isolated CABG Numbers (UK)1991 to 2005

0

10000

20000

30000

40000

50000

60000

70000

80000

19

91

19

92

19

93

19

94

19

95

19

96

19

97

19

98

19

99

20

00

20

01

20

02

20

03

20

04

20

05

PCI

CABG

2005 data: Ludman


Coronary angiography


Normal Right Coronary Artery


The problem


Angioplasty and Stenting


An Actual PCI Procedure


Boston Scientific Taxus Express Stent SystemMDA/2004/033, MDA/2004/036

Failure of some balloons to deflate following stent insertion.

Very large product recall complicated by shelf life and large stocks

UK recall approx 15000 units- extended to 16,000 taxus and 23,000 express stents in 2004/36 notice.

2 Deaths + 25 severe myocardial infarctions worldwide


Taxus Express Balloon Design

Inflation/deflation port

Balloon

At high pressure the inflation/deflation tube partially collapses inside the balloon preventing complete emptying of the balloon


Taxus Express consequences

Very expensive to the company

Boston produced a new manufacturing step which they say eliminates the problem

MHRA says it has reviewed corrective action by the company

Taxus superseded by a new stent the Taxus Liberte which Boston says is unaffected.


Taxus Express

Who should the User believe? Should the Trust have a view as to a particular

company’s overall propriety? Is follow up required from this notification Are your supplies departments included in the

MDA alert cascade? I personally only use a Boston Stent if there is

no other alternative available.


Inventory control – Yorkshire Heart Centre

6 Cardiac Catheter Laboratories

4000 Interventions per year

96 % stent usage, 1.7 stents per case

50% of cases are acute transfers

800 separate consumable stock items

Many have short use by dates

£30-50,000 spend per day on intervention

Approx £1,000,000 stock held


Dual Chamber Pacemaker InsertionPacing rate / million Leeds PCT’s– Age corrected 2005

0 100 200 300 400 500 600 700

Calderdale

Wakefield E

Bradford S&W

Bradford N

Bradford City

N Kirklees

Harrogate

Selby/York

Huddersfield S

Airedale

Huddersfield C

Wakefield W

Leeds NE

Leeds NW

Leeds E

Leeds W

Leeds S

Network average 359

National average 411


Dual-Chamber Pacing

Atrial ‘J’ Lead

‘Straight’ Ventricular Lead


Bipolar Pacing Lead Construction

Outer insulationOuter coil

(Anode)

Inner insulation

Inner coil(Cathode )


IS-1 / VS-1 Bipolar Lead Connector

Sealing Rings

TerminalPin

ProximalRing


Fixation Mechanisms

Active fixationScrew-in lead

Passive fixationTined tip

Passive fixationFinned tip


The Inside View


Atrial “J” Lead


Pacemaker Lead Positioning


Telectronics Accufix J retention wire Problem MDA Hazard (94)24 November 1994

MDA Technical Note No54 November 1994

MDA Safety Alert No 55 May 1995

MDA Technical Note No59 October 1995

MDA Pacemaker Technical Note No64 Sep 1996

MDA Safety Alert No 69 October 1997

MDA Safety Alert No 72 August 1998


Accufix Retention Wire – Solid rectangular section stainless steel

Bipolar Conductor

Retention wire is separate and insulated from the main conductors


Accufix Retention Wire – Solid rectangular section stainless steel

Bipolar Conductor

Retention wire fractures and gradually extrudes outside of the wire body


Accufix lead problem

Wire fracture very difficult to see

Very high quality X-ray screening needed in a digital cardiac cath lab.

Wire fracture has no effect on lead performance so no simple way to detect it


Early Fracture


Near full extrusion


Accufix lead Problem

Extruded wire could puncture through heart into the aorta

Initially 6 Deaths and 13 serious injuries in the USA from Tamponade (Blood around the heart)

Initially occurred months or even years after implant

But removal of pacemaker leads carries a risk


Accufix Initial advice

All product withdrawn

All leads to be screened in cath lab 6 monthly

Consider explant of obviously faulty leads

? Explant all leads

2 Deaths in US from lead explantation


Telectronics J-wire was used in other leads

Warnings extended to all Telectronics leads with a J-wire, company initially notified only one lead type.

Companies Never disclose everything!!!

Telectronics company dissolved

Accufix foundation set up to handle litigation and limit liability

This problem stimulated new devices and technologies for pacemaker lead removal


Accufix – Personal Experience

124 leads Implanted

23 Extracted

No Deaths

30 leads STILL IMPLANTED!!

Last MDA technical note 1998

I no longer screen the leads but some do


Conclusions What is the likely duration of a Device Alert? Should recalls call into question manufacturer’s reputations ? Who should make those judgements ? How do you know if an alert is a balanced risk re action or

inaction ? Please talk to your clinicians more in cardiology. High risk areas are cardiology, interventional radiology, theatres

and ITU. We all need more detailed information from MHRA Alerts

which should either be longer or have a technical appendix Never believe anything anyone tells you!


SOD’S Law for DevicesIf it can ******* break Then it will ***** breakNobody likes bad news

ThereforeHazard warnings are always too lateThe Scale of the problem is always

underestimatedThe solution is always over optimistic

Leeds Nuffield Hospital – November 2006 Case Studies in Cardiology Over-Active Implantable Devices!! Dr John Perrins MD FRCP FACC Consultant.

Documents

balloon slide

problem slide

heart slide

stenting slide

ludman slide

ventricular lead slide

wire body slide