Management of hemodynamically stable wide QRS complex tachycardia in patients with implantable cardioverter defibrillators

Abstract

Management of hemodynamically stable, incessant wide QRS complex tachycardia (WCT) in patients who already have an implantable cardioverter defibrillator (ICD) is challenging. First-line treatment is performed by medical staff who have no knowledge on programmed ICD therapy settings and there is always some concern for unexpected ICD shock. In these patients, a structured approach is necessary from presentation to therapy. The present review provides a systematic approach in four distinct phases to guide any physician involved in the management of these patients: PHASE I: assessment of hemodynamic status and use of the magnet to temporarily suspend ICD therapies, especially shocks; identification of possible arrhythmia triggers; risk stratification in case of electrical storm (ES).

Phase ii: The preparation phase includes reversal of potential arrhythmia "triggers", mild patient sedation, and patient monitoring for therapy delivery. Based on resource availability and competences, the most adequate therapeutic approach is chosen. This choice depends on whether a device specialist is readily available or not. In the case of ES in a "high-risk" patient an accelerated patient management protocol is advocated, which considers urgent ventricular tachycardia transcatheter ablation with or without mechanical cardiocirculatory support.

Phase iii: Therapeutic phase is based on the use of intravenous anti-arrhythmic drugs mostly indicated in this clinical context are presented. Device interrogation is very important in this phase when sustained monomorphic VT diagnosis is confirmed, then ICD ATP algorithms, based on underlying VT cycle length, are proposed. In high-risk patients with intractable ES, intensive patient management considers MCS and transcatheter ablation.

Phase iv: The patient is hospitalized for further diagnostics and management aimed at preventing arrhythmia recurrences.

Keywords: ICD programming; ICD therapies; anti-tachycardia pacing; treatment of ventricular tachycardia; wide QRS complex tachycardia.

FIGURE 1

Chest X-ray in anterior-posterior and lateral projections are important for the identification of the type of implantable cardioverter defibrillator (ICD) and for the application of the magnet which should be fixed on top of the ICD can for disabling therapies. (A) Panel shows the typical position of a transvenous ICD immediately below the left clavicula. (B) Panel shows the radiologic antero-posterior and lateral projections in an 8 year-old girl with an epicardial ICD and the can located in the epigastric area. In panel (C), the typical position of the S-ICD system is appreciated.

FIGURE 2

Proposed systematic and structured diagnostic tree for the ECG diagnosis of wide QRS complex tachycardia (WCT). AV, atrio-ventricular; V-A II grade block: retrograde “P” wave is present after the end of the QRS complex with a 2:1 sequence; VT, ventricular tachycardia.

FIGURE 3

In this 49 year old patient (Patient 1) with a previous antero-septal infarct several years before, WCT at 190 bpm, QRS axis is deviated to the right; atypical RBBB morphology and the presence of a monophasic R wave in aVR indicate VT. The ECG at rest in sinus rhythm, shows the absence of an R wave from V1-V6 indicative of antero-septal transmural necrosis. Patient 2 presents with a WCT at 180 bpm, with a normal QRS axis and typical LBBB pattern in the precordial leads (QS in V1, monophasic R-wave in V6). QRS morphology in sinus rhythm is the same as the one during tachycardia. Intravenous adenosine, allowed to diagnose atrial tachycardia conducting with LBBB.

FIGURE 4

The different steps of the first phase are summarized.

FIGURE 5

(A) Panel shows the print-out of the S-ICD electrogram of a 46 year old patient with dilatative cardiomyopathy. The ventricular tachycardia at 160 bpm with shock therapies set at 200 bpm. The device electrogram (EGM) shows how there is double-counting of the QRS due to T-wave oversensing and a 80 Joules shock is delivered with successful interruption of the arrhythmia. (B) Panel shows the ECG of the VT. The patient experienced repeated shocks following gastroenteritis with hypokalemia without loss of consciousness. The arrhythmia was successfully controlled by hydration, intravenous KCl, and intravenous 150 mg of amiodarone (the patient was already under chronic treatment with amiodarone).

FIGURE 6

The figure proposes a device-based management algorithm for the treatment of wide QRS complex tachycardia (WCT) in ICD patients, based on the type of ICD, specific ICD features according manufacturer, and stimulation therapies delivery from the atrium (in case of supraventricular tachycardia) or from the ventricle (in case of ventricular tachycardia). AF, atrial fibrillation; CL, cycle length; CPR, cardio-pulmonary resuscitation; CRT-D: cardiac resynchronization ICD; DC ICD, dual-chamber ICD; FVT, fast ventricular tachycardia; MCS, mechanical cardio-circulatory support; PLSGB, percutaneous left stellate ganglion block; PoliVT, polymorphic ventricular tachycardia; S-ICD, subcutaneous ICD; SC ICD, single-chamber ICD; SVT, supraventricular tachycardia; TCA, transcatheter ablation; VT, ventricular tachycardia.

FIGURE 7

Telemetry of a 77 year-old CRT-D male patient with a dilated post-infarct heart disease, severely depressed left ventricular ejection fraction, chronic obstructive lung disease, and renal impairment who presents with electrical storm (“high-risk” profile). On the recording, the initial rhythm is a normal pacing rhythm in VDD modality with some single monomorphic premature ventricular beats (PVBs). A fast ventricular tachycardia (FVT) is triggered by the PVB. The first ATP burst of 14 pulses causes degeneration of the VT into a low-amplitude polymorphic FVT refractory to two ATP burst attempts. A 3rd ramp ATP causes degeneration into ventricular flutter which is terminated after a single ICD shock. This patient was stabilized with endovenous amiodarone and underwent transcatheter ablation on the next day.