Synchronous Ventricular Pacing without Crossing the Tricuspid Valve or Entering the Coronary Sinus—Preliminary Results

Effects of tricuspid valve regurgitation on outcome in patients with cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) has a symptomatic and survival benefit for patients with heart failure (HF), but the percentage of nonresponders remains relatively high. The aims of this study were to assess the clinical significance of baseline tricuspid regurgitation (TR) or worsening TR after implantation of a CRT device on the response to therapy. This is a multicenter retrospective analysis of prospectively collected databases that includes 689 consecutive patients who underwent implantation of CRT. The patients were divided into groups according to baseline TR grade and according to worsening TR within 15 months after device implantation. Outcome was assessed by clinical and echocardiographic response within 15 months and by estimated survival for a median interquartile range follow-up time of 3.3 years (1.6, 4.6). TR worsening after CRT implantation was documented in 104 patients (15%). These patients had worse clinical and echocardiographic response to CRT, but worsening of TR was not a significant predictor of mortality (p = 0.17). According to baseline echocardiogram, 620 patients (90%) had some degree of TR before CRT implant. Baseline TR was an independent predictor of worse survival (p <0.001), although these patients had significantly better clinical and echocardiographic response compared with patients without TR. In conclusion, worsening of TR after CRT implantation is a predictor of worse clinical and echocardiographic response but was not significantly associated with increased mortality. Baseline TR is associated with reduced survival despite better clinical and echocardiographic response after CRT implantation.

Synchronous intra-myocardial ventricular pacing without crossing the tricuspid valve or entering the coronary sinus

Ventricular pacing is most commonly performed at the right ventricular (RV) apex. This is not without risk as placement requires crossing the tricuspid valve (TV) and may cause valvular dysfunction and dyssynchronous activation of the ventricles. The fact that the tricuspid valve lies more apically than the mitral valve allows for the possibility of pacing the ventricles from the right atrium (RA) via the "atrio-ventricular septum" without crossing the TV or entering the coronary sinus (CS). In order to mitigate far field activation inherent to current pacing technology, we constructed a novel lead in which the cathode and anode are both intra-myocardial. We demonstrate safety and efficacy of this novel lead for ventricular pacing at the atrio-ventricular septum in canines, including improved synchronous activation of both ventricles, improved differentiation in ventricular versus atrial sensing, while providing reliable ventricular capture, opening novel and a potentially safer alternative to human cardiac resynchronization therapy.

Ventricular resynchronization by implementation of direct his bundle pacing in a patient with congenital complete AV block and newly diagnosed cardiomyopathy

Congenital complete atrioventricular block (CCAVB) is usually due to failure of AV nodal conduction with preservation of the His Purkinje system, typically present at birth. While most patients with CCAVB ultimately require pacemaker therapy to restore physiologic heart rates, recent studies have suggested that chronic right ventricular (RV) pacing in patients with CCAVB can have detrimental effects on cardiac structure and function, and may account for a 7-10% incidence of congestive heart failure in these patients. Since the His Purkinje system is preserved in CCAVB, this patient population could be uniquely well served by direct His bundle pacing (DHBP) which would be expected to restore physiologic activation of both ventricles. We present a case of a young woman who presented with RV pacing-induced cardiomyopathy who responded dramatically to DHBP.