Innovations in cardiac device therapy in the era of advanced rhythm management: implantable defibrillators and conduction system pacing

Figures

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  Figure 1. (A) Timeline of highlights in the evolution of cardiac devices3; (B) Diagrams of the new defibrillation systems. CRT-D, cardiac resynchronisation therapy-defibrillator; FDA, US Food and Drug Administration; ICD, implantable cardioverter-defibrillator.

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  Figure 2. Modular communicative leadless pacing–defibrillator system. A 50-year-old patient with a history of hypertrophic cardiomyopathy (dilated phase), presenting with LVEF of 35%, extensive patchy septal fibrosis on cardiac MRI and narrow QRS. Ambulatory ECG monitoring revealed runs of non-sustained VT lasting up to 37 beats. Patient was considered to be at high risk for monomorphic VT, and implantation of a modular communicative leadless pacing–defibrillator system was indicated for primary prevention of sudden cardiac death (patient included in the MODULAR-ATP trial6 at Hospital Clinic Barcelona). An X-ray of the patient with the implanted device is shown in the figure. The S-ICD uses unidirectional conductive communication to command the leadless pacemaker to deliver ATP. The communication (pulses: 0.5–4 V amplitude, 25 kHz) is coupled to the sensed R-wave and transmitted redundantly (two identical messages are sent to reduce the risk of communication failure).35 Main results of the MODULAR-ATP trial are shown at the bottom of the figure. ATP, antitachycardia pacing; LVEF, left ventricular ejection fraction; S-ICD, subcutaneous implantable cardioverter-defibrillator; VT, ventricular…

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  Figure 3. CRT in 2025. (A) Advantages and disadvantages of CSP and BiVP, as well as an evidence pyramid with the randomised studies currently available and published. (B) CSP with LBBP is a more physiological pacing modality than BiVP; it uses the heart’s intrinsic conduction system and avoids the slow cell-to-cell activation caused by epicardial stimulation (left ventricular pacing through the coronary sinus). BiVP provides an activation characterised by epicardial onset in the lateral left ventricle, with two main foci of activation, left ventricle (in red) and right ventricle. We can see that both techniques correct the baseline dyssynchrony caused by LBBB or RV pacing. LBBP provides a more physiological and homogeneous activation than BiVP. BiVP, biventricular pacing; CRT, cardiac resynchronisation therapy; CSP, conduction system pacing; IVCD, intraventricular conduction delay; LBBB, left bundle branch block; LBBP, left bundle branch pacing; RV, right ventricular.