Essentials of Pacemakers and ICD’s Rajesh Banker, MD, MPH
Essentials of Pacemakers and ICD’s
Feb 12, 2023
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Essentials for pacemakers and ICD's-2Rajesh Banker, MD, MPH
providing rate responsive pacing • Provide diagnostic information stored by the
pacemaker
3
• More uncommonly, prophylaxis can be considered as well
• Sinus Nodal dysfunction or high grade heart block with very low baseline heart rates (<35)
• Bradycardia dependent ventricular tachyarrhythmia
Implantable pulse generator (IPG)
Courtesy www.medtronicacademy.com
• Contains a battery that provides the energy for sending electrical impulses to the heart
• Houses the circuitry that controls pacemaker operations
Circuitry
Battery
• Deliver electrical impulses from the pulse generator to the heart
• Sense cardiac depolarization
Courtesy www.medtronicacademy.com
Types of Leads
• Passive fixation – The tines become
lodged in the trabeculae of the heart
Courtesy www.medtronicacademy.com
Transvenous Leads
extends into the endocardial tissue
– Allows for lead positioning anywhere in the heart’s chamber
Courtesy www.medtronicacademy.com
– Fixation mechanisms include:
Courtesy www.medtronicacademy.com
• Leads or wires • Cathode (negative
electrode) • Anode (positive
electrode) • Body tissue
IPG
Lead
Anode
Cathode
Pacemaker Components Combine with Body Tissue to Form a Complete Circuit
Courtesy www.medtronicacademy.com
• Flows through the lead and the cathode (–)
• Stimulates the heart • Returns to the anode (+)
During Pacing, the Impulse:
fluid and tissue to the IPG (anode)
A Unipolar Pacing System Contains a Lead with Only One Electrode Within the Heart; In This System, the Impulse:
Cathode
Anode
Anode
• Flows through the tip electrode located at the end of the lead wire
• Stimulates the heart • Returns to the ring
electrode above the lead tip
A Bipolar Pacing System Contains a Lead with Two Electrodes Within the Heart. In This System, the Impulse:
Cathode
Courtesy www.medtronicacademy.com
Unipolar leads
• Unipolar leads may have a smaller diameter lead body than bipolar leads
• Unipolar leads usually exhibit larger pacing artifacts on the surface ECG
Courtesy www.medtronicacademy.com
Bipolar leads
Coaxial Lead Design
Rate Responsive Pacing
When the need for oxygenated blood increases, the pacemaker ensures that the heart rate increases to provide additional cardiac output
Adjusting Heart Rate to Activity
Normal Heart Rate
Daily Activities
Courtesy www.medtronicacademy.com
A Variety of Rate Response Sensors Exist
• Those most accepted in the market place are: – Activity sensors that detect physical movement and increase the rate
according to the level of activity – Minute ventilation sensors that measure the change in respiration rate and
tidal volume via transthoracic impedance readings
Rate Responsive Pacing
• Activity sensors employ a piezoelectric crystal that detects mechanical signals produced by movement
• The crystal translates the mechanical signals into electrical signals that in turn increase the rate of the pacemaker
Piezoelectric crystal
Courtesy www.medtronicacademy.com
Rate Responsive Pacing
• Minute ventilation can be measured by measuring the changes in electrical impedance across the chest cavity to calculate changes in lung volume over time
21
A (atrium) A T (triggered) R (rate responsive)
V (ventricle) V I (inhibited)
D (both atrium & ventricle)
D (both atrium & ventricle)
D (both atrium & ventricle)
Lead Dislodgement
Venous thrombosis
Causes: • Threshold rise (electrolytes, drugs) • Lead dislodgement • Lead fracture • RV infarct
Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 7th ed., 2005.
Problems with Pacemakers Failure to Pace
Causes: • Oversensing • Battery failure • Internal insulation failure • Conductor coil fracture
Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 7th ed., 2005.
Problems with Pacemakers Failure to Sense
Causes: • Undersensing • Lead Fracture
Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 7th ed., 2005.
26
What’s next for pacemakers?
Leadless Pacemakers St. Jude Medical and Medtronic devices have concluded their clinical trials
27
Approval expected this year
T h e n e w e ngl a nd j o u r na l o f m e dic i n e
n engl j med nejm.org 1
From the Icahn School of Medicine at Mount Sinai (V.Y.R., S.R.D.) and Weill Cornell Medical Center ( J.E.I.) — both in New York; Libin Cardiovascular Institute of Alberta, Calgary, Canada (D.V.E.); Cleveland Clinic, Cleveland (D.J.C.); Keck Hospital of University of Southern Cali- fornia, Los Angeles (R.D.), and Premier Cardiology, Newport Beach (R.B.) — both in California; Intermountain Medi- cal Center Heart Institute, Salt Lake City, (T.J.B.); Central Baptist Hospital, Lexing- ton, KY (G.F.T.); Mayo Clinic, Rochester, MN (P.A.F.); Tufts University School of Medicine, Boston (N.A.M.E.); Sparrow Clinical Research Institute, Lansing, MI (J.I.); Aurora Medical Group, Milwaukee (I.N.); Naples Community Hospital, Na- ples, FL (K.P.); and Methodist University Hospital, Memphis, TN (J.P.). Address reprint requests to Dr. Reddy at the Icahn School of Medicine at Mount Sinai, 1 Gus- tave L. Levy Pl., Box 1030, New York, New York 10029, or at vivek . reddy@ mountsinai . org.
*A complete list of investigators in the LEADLESS II study is provided in the Supplementary Appendix, available at NEJM.org.
This article was published on August 30, 2015, at NEJM.org.
DOI: 10.1056/NEJMoa1507192 Copyright © 2015 Massachusetts Medical Society.
BACKGROUND Cardiac pacemakers are limited by device-related complications, notably infection and problems related to pacemaker leads. We studied a miniaturized, fully self-con- tained leadless pacemaker that is nonsurgically implanted in the right ventricle with the use of a catheter.
METHODS In this multicenter study, we implanted an active-fixation leadless cardiac pacemaker in patients who required permanent single-chamber ventricular pacing. The primary efficacy end point was both an acceptable pacing threshold (≤2.0 V at 0.4 msec) and an acceptable sensing amplitude (R wave ≥5.0 mV, or a value equal to or greater than the value at implantation) through 6 months. The primary safety end point was free- dom from device-related serious adverse events through 6 months. In this ongoing study, the prespecified analysis of the primary end points was performed on data from the first 300 patients who completed 6 months of follow-up (primary cohort). The rates of the efficacy end point and safety end point were compared with perfor- mance goals (based on historical data) of 85% and 86%, respectively. Additional outcomes were assessed in all 526 patients who were enrolled as of June 2015 (the total cohort).
RESULTS The leadless pacemaker was successfully implanted in 504 of the 526 patients in the total cohort (95.8%). The intention-to-treat primary efficacy end point was met in 270 of the 300 patients in the primary cohort (90.0%; 95% confidence interval [CI], 86.0 to 93.2, P = 0.007), and the primary safety end point was met in 280 of the 300 patients (93.3%; 95% CI, 89.9 to 95.9; P<0.001). At 6 months, device-related serious adverse events were observed in 6.7% of the patients; events included device dislodgement with percutaneous retrieval (in 1.7%), cardiac perforation (in 1.3%), and pacing-threshold elevation requiring percutaneous retrieval and device replace- ment (in 1.3%).
CONCLUSIONS The leadless cardiac pacemaker met prespecified pacing and sensing requirements in the large majority of patients. Device-related serious adverse events occurred in ap- proximately 1 in 15 patients. (Funded by St. Jude Medical; LEADLESS II ClinicalTrials .gov number, NCT02030418.)
A BS TR AC T
Percutaneous Implantation of an Entirely Intracardiac Leadless Pacemaker
Vivek Y. Reddy, M.D., Derek V. Exner, M.D., M.P.H., Daniel J. Cantillon, M.D., Rahul Doshi, M.D., T. Jared Bunch, M.D., Gery F. Tomassoni, M.D., Paul A. Friedman, M.D., N.A. Mark Estes III, M.D., John Ip, M.D., Imran Niazi, M.D., Kenneth Plunkitt, M.D., Rajesh Banker, M.D.,
James Porterfield, M.D., James E. Ip, M.D., and Srinivas R. Dukkipati, M.D., for the LEADLESS II Study Investigators*
Original Article
All modern defibrillators have all the functions a pacemaker plus:
The ability to pace terminate or defibrillate ventricular tachyarrhythmias (VT/VF)
System-wise, the only differences are: The RV lead which has 1 or 2 defibrillator coils on it The pulse generator is larger to accommodate a larger capacitor and battery
29
• High risk subgroups: • Low EF • Genetic syndromes
• Less commonly, ICDs are implanted for presumed or actual cardiac arrest
• VT/VF without a reversible cause • Syncope with concerning history or findings at EP
Study (presumed arrest)
How do ICDs work?
Constant sensing by the RV lead for the presence of a fast rhythm
The threshold for detection is user definable ICDs can discriminate between SVT and Ventricular based tachyarrhythmia (VT/VF)
32
How do ICDs work?
Once VT/VF is detected, the device has a choice: Pace termination Defibrillation
33
Pace Termination More commonly known as Anti-tachy pacing (ATP) Painless
34
Defibrillation
The ICD will charge its capacitor (3-6 seconds) and then deliver therapy
35
providing rate responsive pacing • Provide diagnostic information stored by the
pacemaker
3
• More uncommonly, prophylaxis can be considered as well
• Sinus Nodal dysfunction or high grade heart block with very low baseline heart rates (<35)
• Bradycardia dependent ventricular tachyarrhythmia
Implantable pulse generator (IPG)
Courtesy www.medtronicacademy.com
• Contains a battery that provides the energy for sending electrical impulses to the heart
• Houses the circuitry that controls pacemaker operations
Circuitry
Battery
• Deliver electrical impulses from the pulse generator to the heart
• Sense cardiac depolarization
Courtesy www.medtronicacademy.com
Types of Leads
• Passive fixation – The tines become
lodged in the trabeculae of the heart
Courtesy www.medtronicacademy.com
Transvenous Leads
extends into the endocardial tissue
– Allows for lead positioning anywhere in the heart’s chamber
Courtesy www.medtronicacademy.com
– Fixation mechanisms include:
Courtesy www.medtronicacademy.com
• Leads or wires • Cathode (negative
electrode) • Anode (positive
electrode) • Body tissue
IPG
Lead
Anode
Cathode
Pacemaker Components Combine with Body Tissue to Form a Complete Circuit
Courtesy www.medtronicacademy.com
• Flows through the lead and the cathode (–)
• Stimulates the heart • Returns to the anode (+)
During Pacing, the Impulse:
fluid and tissue to the IPG (anode)
A Unipolar Pacing System Contains a Lead with Only One Electrode Within the Heart; In This System, the Impulse:
Cathode
Anode
Anode
• Flows through the tip electrode located at the end of the lead wire
• Stimulates the heart • Returns to the ring
electrode above the lead tip
A Bipolar Pacing System Contains a Lead with Two Electrodes Within the Heart. In This System, the Impulse:
Cathode
Courtesy www.medtronicacademy.com
Unipolar leads
• Unipolar leads may have a smaller diameter lead body than bipolar leads
• Unipolar leads usually exhibit larger pacing artifacts on the surface ECG
Courtesy www.medtronicacademy.com
Bipolar leads
Coaxial Lead Design
Rate Responsive Pacing
When the need for oxygenated blood increases, the pacemaker ensures that the heart rate increases to provide additional cardiac output
Adjusting Heart Rate to Activity
Normal Heart Rate
Daily Activities
Courtesy www.medtronicacademy.com
A Variety of Rate Response Sensors Exist
• Those most accepted in the market place are: – Activity sensors that detect physical movement and increase the rate
according to the level of activity – Minute ventilation sensors that measure the change in respiration rate and
tidal volume via transthoracic impedance readings
Rate Responsive Pacing
• Activity sensors employ a piezoelectric crystal that detects mechanical signals produced by movement
• The crystal translates the mechanical signals into electrical signals that in turn increase the rate of the pacemaker
Piezoelectric crystal
Courtesy www.medtronicacademy.com
Rate Responsive Pacing
• Minute ventilation can be measured by measuring the changes in electrical impedance across the chest cavity to calculate changes in lung volume over time
21
A (atrium) A T (triggered) R (rate responsive)
V (ventricle) V I (inhibited)
D (both atrium & ventricle)
D (both atrium & ventricle)
D (both atrium & ventricle)
Lead Dislodgement
Venous thrombosis
Causes: • Threshold rise (electrolytes, drugs) • Lead dislodgement • Lead fracture • RV infarct
Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 7th ed., 2005.
Problems with Pacemakers Failure to Pace
Causes: • Oversensing • Battery failure • Internal insulation failure • Conductor coil fracture
Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 7th ed., 2005.
Problems with Pacemakers Failure to Sense
Causes: • Undersensing • Lead Fracture
Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 7th ed., 2005.
26
What’s next for pacemakers?
Leadless Pacemakers St. Jude Medical and Medtronic devices have concluded their clinical trials
27
Approval expected this year
T h e n e w e ngl a nd j o u r na l o f m e dic i n e
n engl j med nejm.org 1
From the Icahn School of Medicine at Mount Sinai (V.Y.R., S.R.D.) and Weill Cornell Medical Center ( J.E.I.) — both in New York; Libin Cardiovascular Institute of Alberta, Calgary, Canada (D.V.E.); Cleveland Clinic, Cleveland (D.J.C.); Keck Hospital of University of Southern Cali- fornia, Los Angeles (R.D.), and Premier Cardiology, Newport Beach (R.B.) — both in California; Intermountain Medi- cal Center Heart Institute, Salt Lake City, (T.J.B.); Central Baptist Hospital, Lexing- ton, KY (G.F.T.); Mayo Clinic, Rochester, MN (P.A.F.); Tufts University School of Medicine, Boston (N.A.M.E.); Sparrow Clinical Research Institute, Lansing, MI (J.I.); Aurora Medical Group, Milwaukee (I.N.); Naples Community Hospital, Na- ples, FL (K.P.); and Methodist University Hospital, Memphis, TN (J.P.). Address reprint requests to Dr. Reddy at the Icahn School of Medicine at Mount Sinai, 1 Gus- tave L. Levy Pl., Box 1030, New York, New York 10029, or at vivek . reddy@ mountsinai . org.
*A complete list of investigators in the LEADLESS II study is provided in the Supplementary Appendix, available at NEJM.org.
This article was published on August 30, 2015, at NEJM.org.
DOI: 10.1056/NEJMoa1507192 Copyright © 2015 Massachusetts Medical Society.
BACKGROUND Cardiac pacemakers are limited by device-related complications, notably infection and problems related to pacemaker leads. We studied a miniaturized, fully self-con- tained leadless pacemaker that is nonsurgically implanted in the right ventricle with the use of a catheter.
METHODS In this multicenter study, we implanted an active-fixation leadless cardiac pacemaker in patients who required permanent single-chamber ventricular pacing. The primary efficacy end point was both an acceptable pacing threshold (≤2.0 V at 0.4 msec) and an acceptable sensing amplitude (R wave ≥5.0 mV, or a value equal to or greater than the value at implantation) through 6 months. The primary safety end point was free- dom from device-related serious adverse events through 6 months. In this ongoing study, the prespecified analysis of the primary end points was performed on data from the first 300 patients who completed 6 months of follow-up (primary cohort). The rates of the efficacy end point and safety end point were compared with perfor- mance goals (based on historical data) of 85% and 86%, respectively. Additional outcomes were assessed in all 526 patients who were enrolled as of June 2015 (the total cohort).
RESULTS The leadless pacemaker was successfully implanted in 504 of the 526 patients in the total cohort (95.8%). The intention-to-treat primary efficacy end point was met in 270 of the 300 patients in the primary cohort (90.0%; 95% confidence interval [CI], 86.0 to 93.2, P = 0.007), and the primary safety end point was met in 280 of the 300 patients (93.3%; 95% CI, 89.9 to 95.9; P<0.001). At 6 months, device-related serious adverse events were observed in 6.7% of the patients; events included device dislodgement with percutaneous retrieval (in 1.7%), cardiac perforation (in 1.3%), and pacing-threshold elevation requiring percutaneous retrieval and device replace- ment (in 1.3%).
CONCLUSIONS The leadless cardiac pacemaker met prespecified pacing and sensing requirements in the large majority of patients. Device-related serious adverse events occurred in ap- proximately 1 in 15 patients. (Funded by St. Jude Medical; LEADLESS II ClinicalTrials .gov number, NCT02030418.)
A BS TR AC T
Percutaneous Implantation of an Entirely Intracardiac Leadless Pacemaker
Vivek Y. Reddy, M.D., Derek V. Exner, M.D., M.P.H., Daniel J. Cantillon, M.D., Rahul Doshi, M.D., T. Jared Bunch, M.D., Gery F. Tomassoni, M.D., Paul A. Friedman, M.D., N.A. Mark Estes III, M.D., John Ip, M.D., Imran Niazi, M.D., Kenneth Plunkitt, M.D., Rajesh Banker, M.D.,
James Porterfield, M.D., James E. Ip, M.D., and Srinivas R. Dukkipati, M.D., for the LEADLESS II Study Investigators*
Original Article
All modern defibrillators have all the functions a pacemaker plus:
The ability to pace terminate or defibrillate ventricular tachyarrhythmias (VT/VF)
System-wise, the only differences are: The RV lead which has 1 or 2 defibrillator coils on it The pulse generator is larger to accommodate a larger capacitor and battery
29
• High risk subgroups: • Low EF • Genetic syndromes
• Less commonly, ICDs are implanted for presumed or actual cardiac arrest
• VT/VF without a reversible cause • Syncope with concerning history or findings at EP
Study (presumed arrest)
How do ICDs work?
Constant sensing by the RV lead for the presence of a fast rhythm
The threshold for detection is user definable ICDs can discriminate between SVT and Ventricular based tachyarrhythmia (VT/VF)
32
How do ICDs work?
Once VT/VF is detected, the device has a choice: Pace termination Defibrillation
33
Pace Termination More commonly known as Anti-tachy pacing (ATP) Painless
34
Defibrillation
The ICD will charge its capacitor (3-6 seconds) and then deliver therapy
35
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