Hands-onImplantable cardioverter-defibrillators in congenital heart disease: 10 programming tips
Introduction
Advances in cardiac care of the young have given rise to a growing and aging population of patients with congenital heart disease. Despite remarkable improvements in overall survival, sudden cardiac death remains the most common cause of late mortality. As a result, implantable cardioverter-defibrillators (ICDs) are increasingly used in this heterogeneous patient population. Tetralogy of Fallot and transposition of the great arteries are the most prevalent subtypes of congenital heart disease in ICD recipients.1, 2, 3 Common to this young population is the high rate of lead-related complications and inappropriate shocks.1, 2, 3 In a multicenter study of patients with tetralogy of Fallot, 25% received inappropriate shocks, predominantly due to sinus or supraventricular tachycardia.1 Although a similar proportion of patients with transposition received inappropriate shocks (24%), 62% were due to oversensing or lead dysfunction.3 Herein, we offer 10 practical tips for optimizing ICD programming in patients with congenital heart disease (Table 1) in view of reducing inappropriate and potentially avoidable shocks.
Section snippets
Faster cutoff rates
In ICD recipients in general, ventricular tachyarrhythmias typically are faster in patients with primary compared to secondary prevention indications, averaging 200 bpm versus 150 to 160 bpm, respectively.4 Because supraventricular tachycardia (SVT) generally ranges between 160 and 180 bpm, the ventricular fibrillation (VF) zone is often programmed between 182 and 188 bpm in patients with primary prevention ICDs at large. One could argue, however, that a higher cutoff rate (e.g., 200 bpm) would
Monitoring zones
Monitoring zones may detect slow VT and asymptomatic atrial arrhythmias, which are common in patients with surgically corrected congenital heart disease. With the exception of Sorin devices, monitoring zones are free from interactions with active zones. Thus, in contemporary ICDs, there is no major deterrent to programming monitoring zones. It should be noted, however, that if onset/stability discriminators are programmed in Guidant monitoring zones, discriminators are withheld in the active
Longer detection times
Programming ICDs for treatment of “sustained” ventricular tachyarrhythmias entails a compromise between overtreating otherwise self-terminating events and delaying therapy for potentially unstable arrhythmias. Whereas earlier ICD trials required 12 of 16 intervals to detect VF, longer detection times subsequently have been advocated.5 This criterion was later extended to 18 of 24 intervals, with no increase in adverse events. The safety of programming 30 of 40 intervals to detect VF was
Fast VT zones to allow antitachycardia pacing
Solid evidence now supports antitachycardia pacing (ATP) as a painless and effective therapy to terminate VT. In patients with congenital heart disease, ATP as the first appropriate therapy was successful in 79% of cases.1, 3 Randomized clinical trials in noncongenital patients have indicated no increased rate of syncope, death, or VT acceleration.6 More recent studies compared a standardized single ATP sequence in the fast VT zone with physician-tailored programming.7, 8 Significantly fewer
Rate smoothing
Rate smoothing reduces the maximum variation in cycle length by a programmable value. It is available in Guidant/Boston, Medtronic, and Sorin devices. By minimizing short–long–short intervals, rate smoothing was developed to reduce the ventricular arrhythmia burden. Although the impact of rate smoothing has not been assessed in congenital heart disease, initial studies suggested benefit in patients with long QT syndrome.12 However, subsequent case reports have cautioned against underdetection
Avoid or extend “high rate time out/sustained rate duration”
“High rate time out” and “sustained rate duration” are timers to override discriminators. Once the timer elapses, therapy is delivered even if it had been appropriately withheld. Designed as a safety feature in the event that VT is misclassified as SVT, these timers are an important source of inappropriate shocks because SVT episodes often last longer than the duration of the timer.11 Moreover, the literature suggests that this safety feature is of little value, with no reported adverse events
ATP in VF zone when available
The weight of evidence suggests that at least one ATP sequence should be programmed for VTs between 188 and 250 bpm and that two sequences are superior to one. ATP for VT faster than 250 bpm appears safe, albeit less effective. Medtronic ATP during charging can be activated for rhythms over 250 bpm. ATP during charging currently is not available in St. Jude devices but will be integrated in recently approved Fortify ICDs. Boston's Quickconvert delivers one ATP sequence in the VF zone before
Number of ATP sequences (at least 2 in faster VT zones and 4–6 in slower VT zones)
In fast VT zones, the success rate with two ATP sequences is superior to one, with the second terminating 35% of VTs. For induced VTs faster than 250 bpm, a 30% success rate was noted with up to 6 ATP sequences.15 Although rate acceleration occurred in 24%, all shocks ultimately were successful. Programming ATP for VT slower than 180 bpm is common practice, but evidence-based strategies (e.g., number of sequences and stimuli, burst versus ramp) are scarce. One study compared four settings:
Shock output
To our knowledge, no study has specifically compared incremental versus high-energy shocks. Advantages of low-energy shocks include shorter charge times, extended battery life, and possibly less myocardial damage. Nevertheless, in the modern era, charge time is not a major issue, and higher-energy shocks carry a greater probability of success. Additional advantages of high-energy shocks may include a higher probability of terminating inappropriately treated SVTs (for which the shock vector is
Conclusion
Although carefully selected patients with congenital heart disease undoubtedly are benefitting from ICDs, enthusiasm for this potentially lifesaving therapy is tempered by the high rate of complications. Encouragingly, many inappropriate or unnecessary distressful shocks may be prevented by tailored ICD programming. The one-zone “shock box” approach should be considered obsolete in light of the growing body of evidence demonstrating the safety and superiority of alternate strategies to reduce
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2023, Cardiac Electrophysiology ClinicsSudden Cardiac Death in Adult Congenital Heart Disease
2017, Cardiac Electrophysiology ClinicsPacemaker and Implantable Cardioverter-Defibrillator Management in Children and Congenital Heart Disease
2016, Clinical Cardiac Pacing, Defibrillation and Resynchronization TherapyPACES/HRS expert consensus statement on the recognition and management of arrhythmias in adult congenital heart disease: Developed in partnership between the Pediatric and Congenital Electrophysiology Society (PACES) and the Heart Rhythm Society (HRS). Endorsed by the governing bodies of PACES, HRS, the American College of Cardiology (ACC), the American Heart Association (AHA), the European Heart Rhythm Association (EHRA), the Canadian Heart Rhythm Society (CHRS), and the International Society for Adult Congenital Heart Disease (ISACHD)
2014, Heart RhythmCitation Excerpt :In the absence of rate-dependent aberrancy, morphology discrimination algorithms may be beneficial in these circumstances. However, programming according to prior history of supraventricular tachycardia is not always reliable because adults with CHD may have multiple supraventricular substrates with differing rates and conduction characteristics.495 Nevertheless, programming discriminators in slower zones appears justified to avoid inappropriate shocks.
PACES/HRS Expert Consensus Statement on the Recognition and Management of Arrhythmias in Adult Congenital Heart Disease
2014, Canadian Journal of CardiologyCitation Excerpt :Nevertheless, programming discriminators in slower zones appears justified to avoid inappropriate shocks. If discriminators are not activated, they should be programmed to a passive mode to assist in defining future cutoff values.495 For patients with secondary prevention ICDs, a safety margin of 30-60 ms between the slowest spontaneous or induced ventricular tachycardia and the cutoff rate may be reasonable for the ventricular tachycardia zone, the upper limit being more appropriate in the presence of antiarrhythmic drugs.495
Electrophysiologic therapeutics in heart failure in adult congenital heart disease
2014, Heart Failure ClinicsCitation Excerpt :High rates of inappropriate shocks have consistently been reported as a result of coexisting supraventricular tachyarrhythmias and lead failures (see Table 2).139,147,148 ICDs should be programmed carefully, bearing in mind the potential psychological burden of inappropriate discharges.149 Strategies may include programming 2 VT detection zones with activation of ATP, programming higher defibrillation detection thresholds and/or prolonging time to detection, and the use of tailored supraventricular tachycardia discrimination algorithms to prevent unnecessary shocks.141,149–154
This work was supported in part by the Canada Research Chair in Electrophysiology and Adult Congenital Heart Disease (PK). Dr. Mansour has served as a consultant for Biotronik.