Circulation. 2002;106:2642-2646
doi: 10.1161/01.CIR.0000041503.01975.6A
(Circulation. 2002;106:2642.)
© 2002 American Heart Association, Inc.
Management of the Patient With an Implantable Cardioverter-Defibrillator in the Third Millennium
Sanjeev Saksena, MD, FESC;
Nandini Madan, MBBS, MD
From the Arrhythmia and Pacemaker Service, Cardiovascular Institute, Atlantic Health System (Passaic), the Department of Medicine, RWJ Medical School, New Brunswick (S.S.), and The Electrophysiology Research Foundation, Warren (N.M.), NJ.
Reprint requests to Sanjeev Saksena, MD, Clinical Professor of Medicine, Director, Cardiovascular Institute, 513 Warrenville Rd, Suite 2A, Warren, NJ 07059. E-mail CMENJ{at}aol.com
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Introduction
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Implantable cardioverter-defibrillator (ICD) devices were originally
developed for prevention of sudden cardiac death (SCD). They
are now widely regarded as the primary therapy for this condition.
Clinical trials have led to a progressive expansion in indications
for their use.
1,2 Recent clinical reports show effectiveness
of these devices in patients with recurrent syncope, in the
prevention of SCD in high-risk patients with coronary disease,
and in the treatment of atrial fibrillation. Refinements in
ICD technology have improved functionality and enhanced safety.
Optimal patient management requires intimate knowledge of these
complex devices and of the diverse arrhythmias that may be treatable
by a single multifaceted ICD device.
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Case Study
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A 75-year-old man presented with near-syncope and ventricular
arrhythmias. He had a past history of dilated cardiomyopathy,
old cerebrovascular accident, symptomatic atrial flutter/fibrillation,
and heart failure. He had been treated with anticoagulation
and antiarrhythmic drugs, but it was noted on admission that
he was in atrial flutter with a ventricular rate of 110 bpm.
Electrophysiological evaluation revealed isthmus- (common or
typical) and nonisthmus- (atypical) dependent atrial flutter
and inducible hypotensive monomorphic sustained ventricular
tachycardia. A linear ablation of the tricuspid valve-inferior
vena cava isthmus interrupted common flutter, but atypical flutter
persisted. The following day, a dual chamber ICD capable of
defibrillation and antitachycardia, as well as standard demand
pacing in both chambers, was inserted. An additional coronary
sinus lead was placed to permit dual site right atrial pacing
for prevention of atrial flutter and fibrillation (
Figure 1A).
The patient was given a handheld activator for termination of
atrial fibrillation (AF) and flutter.
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Figure 1. A, Lateral radiograph of the chest showing the first dual chamber atrioventricular defibrillator inserted in patient with refractory atrial fibrillation. Note the distinct atrial and ventricular pacing and defibrillation leads. An additional coronary sinus pacing lead is placed outside the ostium for dual site right atrial pacing. B, Noninvasive electrophysiological stimulation to evaluate ventricular defibrillation efficacy in a dual chamber ICD. The top trace shows atrial electrograms, the middle trace shows current application, and the lower trace shows ventricular electrograms. P and R markers are annotations of the two electrograms and intervals are shown in ms. A DC current is applied during sinus rhythm and initiates both atrial and ventricular fibrillation. Both rapid rhythms are detected and correctly diagnosed with AV dissociation. Ventricular defibrillation is performed with a 541 V leading edge voltage shock that terminates both rhythms. C, Programmer screen shows measured data on atrial and ventricular lead function in dual chamber ICD. D, Arrhythmia logbook showing episodes of ventricular fibrillation with time-date stamp and access to stored electrograms in a dual chamber ICD.
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Advances in ICD Technology
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Over two decades, ICDs have evolved into multifunctional therapeutic
and monitoring devices.
3 Currently available devices can provide
atrial pacing, rate-responsive pacing, and atrial antitachycardia
pacing and defibrillation. New algorithms provide reliable discrimination
of supraventricular and ventricular tachyarrhythmias and prevent
arrhythmias. Diagnostic and monitoring capabilities enable the
ICD to evaluate its own component functions and permit automated
testing functions for system performance, record of arrhythmic
events, and delivered interventional therapies. It can store
information relative to patient or arrhythmia status. ICD generator
longevity has now improved so that most devices are rated for
4 or more years, depending on the electrical current drain for
activated features.
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Single Chamber Ventricular ICD Technology
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In its simplest iteration, the ICD device is capable of detecting
and treating ventricular tachyarrhythmias and permitting ventricular
pacing and monitoring of ventricular rhythm. Ventricular rhythm
detection in these systems is based on ventricular electrogram
rate, regularity, morphology, and patterns of electrogram interval
changes. In general, a minimum of two-zone programming is usually
performed for discrimination of a monomorphic ventricular tachycardia
from ventricular fibrillation. In some instances, when prophylaxis
from ventricular fibrillation alone is needed, as in patients
with long QT syndrome, a single zone may suffice. When empirical
programming is sought in patients with VT or cardiac arrest,
we prefer to establish three zones for "slow" ventricular tachycardia,
"fast" monomorphic ventricular tachyarrhythmias, and ventricular
fibrillation.
4 Such discrimination is useful for clinical and
therapeutic purposes. The slowest zone is usually associated
with nonsyncopal rhythms, and these are often responsive to
antitachycardia pacing. Antitachycardia pacing is most effective
in termination of monomorphic ventricular tachycardia, especially
with rates below 180 bpm, and has efficacy rates of >80%.
5 The second zone is often associated with significant symptoms,
but early cardioversion with a rapid change time and a lower
energy shock may abort syncope. For cardioversion of fast ventricular
tachycardia, a 5-joule biphasic waveform shock can achieve approximately
80% success.
4 Ventricular fibrillation produces syncope in many
patients and requires a highly effective shock. Initial defibrillation
energy programming is based on the defibrillation threshold.
Repeated efficacy of the lowest successful energy is needed
to place the shock near the threshold, with three successive
or repeated successful terminations being needed for this level
of efficacy (
Figure 1B). An increasing trend to limit device
testing may compromise confidence in the ICD’s ability
to defibrillate when new drugs, heart failure, or ischemia potentially
raise defibrillation thresholds.
Electrogram morphology is now available to differentiate supraventricular and ventricular tachyarrhythmias. In the absence of intraventricular conduction abnormalities, supraventricular rhythms can often be identified by matching their ventricular electrogram morphology to a sinus rhythm template. Monitoring and testing functions provide for more automated device-based testing, with expanded capabilities that include continuous arrhythmia detection and noninvasive electrophysiological testing (Figure 1C and Movie). An additional feature specific to defibrillators is the capacitor charge time to maximal shock delivery. This used to be a key manual test performed at follow-up but now can be automatically initiated by the device at prespecified intervals of time. Charge times in excess of 12 seconds merit close attention and frequent follow-up, and those in excess of 15 seconds merit generator replacement. During follow-up, the patient’s arrhythmia history is readily available. Tachyarrhythmic events are logged, their durations are recorded, and in most devices, recorded ventricular electrograms are available for a segment of the event (Figure 1D). These monitoring capabilities also contribute to substantial electrical current drain and can limit longevity if used indiscriminately.
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Dual Chamber Ventricular ICD Technology
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Dual chamber ICDs require the insertion of an additional bipolar
lead in the right atrium. Tachycardia discrimination in these
devices uses rate-based detection algorithms overlaid with pattern
analysis of atrial and ventricular electrogram relationships.
Difficulties remain when AV relationships are fixed and the
rates are identical. Rules for discrimination have been established
in device logic and are highly individualized for each device.
Thus, inappropriate atrial lead placement can seriously impair
tachyarrhythmia detection. Rate response is based on an activity
sensor, and multisensor devices are still awaited.
Contemporary indications for dual chamber ICD insertion in patients with ventricular arrhythmias include the standard indications for dual chamber pacing. Dual chamber ICDs are also preferred in patients with coexisting atrial and ventricular tachyarrhythmias, as they enable discrimination of the two types of rhythm disturbances.
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Dual Chamber Atrioventricular ICD Technology
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Dual chamber atrioventricular ICD technology is the latest arrival
on the ICD technology scene. Individualized atrial and ventricular
antitachycardia therapies can be delivered, thus expanding the
potential ICD population of patients who may benefit from an
ICD. Initial studies have been conducted in patients with atrial
fibrillation who may or may not have coexisting lethal ventricular
tachyarrhythmias.
6 Because the pool of patients with atrial
fibrillation is very large and atrial cardioversion is a commonly
used procedure, the future of this technology in a "hybrid"
therapy format, as used in this patient, is quite bright.
7
The atrial channel permits classification of and zone-based therapy for atrial tachyarrhythmias. It requires insertion of an additional atrial defibrillation electrode. Atrial tachyarrhythmia detection is based on a two-zone stratification, with a monomorphic tachycardia zone for atrial tachycardias and flutter and an AF zone. Antitachycardia pacing is available in the tachycardia zone using burst, ramp, or 50 Hz trains. Such 50 Hz trains have been demonstrated to be effective in previously pacing-resistant atypical flutter, with efficacy rates up to 60%.8,9 Backup shock therapy is used if pacing therapies are ineffective. In the AF zone, 50 Hz pacing and shock therapy alone are available (Figure 2). Rapid atrial flutter may be classified and pace-terminated, but established AF rarely responds to this modality. Atrial defibrillation shocks have similar principles of efficacy to ventricular defibrillation. A sigmoid defibrillation efficacy curve exists, and thresholds vary widely with lead configuration. In clinical studies, reliable atrial defibrillation has been obtained with shock energies up to 27 joules.10 Newer iterations of these devices include pacing prevention algorithms such as continuous atrial pacing for AF prevention. Finally, a handheld patient activator is available for delivery of therapy on demand by the patient or physician. Dual chamber atrioventricular defibrillators have been approved for use in patients with drug-refractory and symptomatic atrial fibrillation and in patients with coexisting symptomatic atrial and ventricular tachyarrhythmias.
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Figure 2. A, Electrocardiographic recording of termination of spontaneous atrial tachycardia by a 50 Hz atrial burst delivered by a dual chamber atrioventricular ICD. Transient acceleration is noted before termination. B, Electrocardiographic recording of termination of spontaneous AF by a 6-joule atrial shock delivered by a dual chamber atrioventricular ICD. Transient acceleration is noted before termination. ATT indicates atrial tachyarrhythmia; HFP, high frequency pacing; NSR, normal sinus rhythm; and DDD, dual chamber sensing and pacing.
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Multisite Pacing ICDs
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The latest development is the inclusion of multisite atrial
or ventricular pacing in dual chamber ICDs. In the above-mentioned
patient, an additional coronary sinus ostial pacing lead was
inserted. Dual site right atrial pacing is used to prevent of
symptomatic AF and flutter. Dual site right atrial pacing reduces
intra-atrial conduction delay, abbreviates P wave duration,
prolongs the time to recurrent AF in patients on class 1 or
3 antiarrhythmic drug therapy 2, reduces AF burden, and improves
left atrial filling fraction and A wave velocity on echocardiography.
Programming to avoid oversensing in the ventricle and atrium
is important for optimal device function. This mode can reduce
the need for cardioversion and improve efficacy of "hybrid"
therapy.
Similarly, biventricular pacing has been used for ventricular resynchronization in patients with left bundle branch block, first degree AV block, and refractory class 2 or 3 congestive heart failure.11 In this system, a coronary sinus pacing lead is inserted into the posterolateral left ventricular vein or, as far as clinically feasible, into the distal coronary sinus or its tributaries (Figure 3). Simultaneous pacing at the venous site and the right ventricular apex can abbreviate QRS duration in patients with moderate and severe left bundle branch block (QRS duration >140 ms) and improve left ventricular hemodynamics and exercise capacity. These ICDs achieve both sudden death risk reduction and improved hemodynamics.
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Figure 3. Posteroanterior fluoroscopic image of a dual chamber ICD with biventricular pacing capability. A coronary sinus pacing lead that has been inserted in the posterolateral left ventricular venous branch draining into the coronary sinus is noted. A standard ventricular pacing defibrillation lead is seen in the right ventricular apex, and a conventional high right atrial pacing lead is seen. Biventricular pacing is achieved with simultaneous pacing at the right ventricular apex and left ventricular epicardium.
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Updated Indications for ICD Therapy
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American College of Cardiology/American Heart Association guidelines
for the use of the ICD in ventricular tachyarrhythmias were
published in 1998.
12 New indications for ICD therapy in 2002
may now include asymptomatic patients at high-risk for lethal
ventricular arrhythmias and drug-refractory symptomatic atrial
tachyarrhythmias.
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Implantable Defibrillators for Primary Prevention of Ventricular Arrhythmias
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Subgroups of the patients with the following findings have been
or are being actively evaluated for primary prevention of malignant
ventricular tachyarrhythmias.
- Nonsustained Ventricular Tachycardia With Coronary Artery Disease and Left Ventricular Dysfunction. This patient group is the first primary prevention category evaluated in the Multicenter Automatic Defibrillator Implantation Trial-1 (MADIT-1) study.2 This category of patients has long been recognized to have a high propensity for sudden death. The MADIT-1 study demonstrated a 54% reduction in relative risk of death in these patients as compared with drug therapy. It has been estimated that approximately 3% to 7% of acute myocardial infarction survivors will eventually be stratified into this subgroup.
- Familial Syndromes With High Risk of Sudden Death. The guidelines recognized several important but small patient groups that have familial or acquired diseases that predispose them to sudden death. In most of these categories, small clinical series or pilot data and expert consensus led to adoption of the indication.11 This includes high-risk patients with congenital long QT or Brugada syndromes, hypertrophic cardiomyopathy, and arrhythmogenic right ventricular dysplasia. A family history of sudden death is a key element in selection of the ICD as a primary prevention therapy.
- Refractory Heart Failure Necessitating Cardiac Transplantation. Data from cardiac transplant centers has documented an inordinately high risk of sudden death in individuals awaiting cardiac transplantation. In these individuals, pilot data has shown appropriate ICD prevention of malignant ventricular tachycardias.
- Coronary Artery Disease With Left Ventricular Dysfunction and Left Ventricular Ejection Fraction of <31%. The role of left ventricular dysfunction as an important determinant of survival benefit with defibrillator therapy has been highlighted.13 The MADIT-2 study evaluated the hypothesis that patients with coronary disease and myocardial infarction who had an LV ejection fraction <31% would have improved survival with defibrillator therapy.14 The trial demonstrated a 30% reduction in relative risk, which was estimated to decline from a projected 19% two-year mortality to an actual 14% mortality with defibrillator insertion. Important analyses are in progress to identify the subgroup(s) that derive the most benefit. Initial analyses suggest that these subgroups could include electrophysiological markers, as well as other clinical markers.
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Conclusions
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New, increasingly complex and rapidly evolving ICD technology
has widened indications and clinical application of these devices.
Management of the present day ICD patient requires intimate
knowledge of new device technology and well-organized programs
with facilities for the ICD patient and device surveillance.
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Footnotes
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The Movie is available as an online-only Data Supplement at http://www.circulationaha.org.
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References
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- The Antiarrhythmics Versus Implantable Defibrillators (AVID) Investigators. A comparison of antiarrhythmic-drug therapy with implantable defibrillators in patients resuscitated from near-fatal ventricular arrhythmias. N Engl J Med. 1997; 337: 1576–1583.[Abstract/Free Full Text]
- Moss AJ, Hall WJ, Cannom DS, et al. Improved survival with an implanted defibrillator in patients with coronary artery disease at high risk for ventricular arrhythmia. N Eng J Med. 1997; 335: 1933–1940.
- Saksena S, Prakash A, Madan N, et al. New generations of implantable pacemaker defibrillators for ventricular and atrial tachyarrhythmias. In: El-Sherif N, Lekieffre J, eds. Practical Management of Cardiac Arrhythmias. Armonk, NY: Futura Publishing Co; 1997: 321–332.
- Neglia JJ, Krol RB, Giorgberidze I, et al. Evaluation of a programming algorithm for the third tachycardia zone in a fourth-generation implantable cardioverter-defibrillator. J Interv Card Electrophysiol. 1997; 1: 49–56.[CrossRef][Medline]
[Order article via Infotrieve]
- Saksena S. Clinical outcome of patients with malignant ventricular tachyarrhythmias and a multiprogrammable cardioverter-defibrillator implanted with or without thoracotomy: an international multicenter study. J Am Coll Cardiol. 1994; 23: 1521–1530.[Abstract]
- Jung W, Wolpert C, Esmailzadeh B, et al. Clinical experience with implantable atrial and combined atrioventricular defibrillators. J Interv Card Electrophysiol. 2000; 4 (suppl 1): 185–195.[Medline]
[Order article via Infotrieve]
- Krol RB, Saksena S, Prakash A. New devices and hybrid therapies for treatment of atrial fibrillation. J Interv Card Electrophysiol. 2000; 4 (suppl 1): 163–169.[Medline]
[Order article via Infotrieve]
- Giorgberidze I, Saksena S, Mongeon L, et al. Effects of high-frequency atrial pacing in atypical atrial flutter and atrial fibrillation. J Intervent Card Electrophysiol. 1997; 1: 111–123.[CrossRef][Medline]
[Order article via Infotrieve]
- Adler SW II, Wolpert C, Warman EN, et al. Efficacy of pacing therapies for treating atrial tachyarrhythmias in patients with ventricular arrhythmias receiving a dual-chamber implantable cardioverter defibrillator. Circulation. 2001; 104: 887–892.[Abstract/Free Full Text]
- Saksena S, Prakash A, Mongeon L, et al. Clinical efficacy and safety of atrial defibrillation using biphasic shocks and current nonthoracotomy endocardial lead configurations. Am J Cardiol. 1995; 76: 913–921.[CrossRef][Medline]
[Order article via Infotrieve]
- Sweeney MO, Ellison KE, Stevenson WG. Implantable cardioverter defibrillators in heart failure. Cardiol Clin. 2001; 19: 653–667.[CrossRef][Medline]
[Order article via Infotrieve]
- Gregoratos G, Cheitlin C, Connil A, et al. ACC/AHA guidelines for the implantation of cardiac pacemakers and antiarrhythmia devices: a report on the American College of Cardiology/American Heart Association Committee on Pacemaker Implantation. J Am Coll Cardiol. 1998; 31: 1175–1209.[Free Full Text]
- Domanski M, Saksena S, Epstein AE, et al. Relative effectiveness of the implantable cardioverter-defibrillator and antiarrhythmic drugs in patients with varying degrees of left ventricular dysfunction who have survived malignant ventricular arrhythmias. J Am Coll Cardiol. 1999; 34: 1090–1095.[Abstract/Free Full Text]
- Moss AJ, Zareba W, Hall WJ, et al. Prophylactic implantation of defibrillator in patients with myocardial infarction and reduced left ventricular ejection fraction. N Engl J Med. 2002; 346: 877–883.[Abstract/Free Full Text]
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Introduction
Case Study