Biomedical subjects

Thierry Pochet

Publications and source records attributed to Thierry Pochet.

3 recordsLinked to original sources

PubMed2005

Tailoring cardiac resynchronization therapy using interventricular asynchrony. Validation of a simple model.

This study explores the use of interventricular asynchrony (interVA) for optimizing cardiac resynchronization therapy (CRT), an idea emerging from a simple pathway model of conduction in the ventricles. Measurements were performed in six dogs with chronic left bundle branch block (LBBB) and in 29 patients of the Pacing Therapies for Congestive Heart Failure (PATH-CHF)-I study. In the dogs, intraventricular asynchrony (intraVA) was determined using left ventricular (LV) endocardial activation maps. In dogs and patients, the maximum rate of rise of LV pressure (LV dP/dt(max)) and the pulse pressure (PP) and interVA [time delay between upslope of LV and right ventricular (RV) pressure curves] were measured during LV, RV, and biventricular (BiV) pacing with various atrioventricular (AV) delays. Measurements in the canine hearts supported the pathway model in that optimal resynchronization occurred at approximately 50% reduction of intraVA and at an interVA value halfway that during LBBB and LV pacing. In patients with significant hemodynamic response during pacing (n = 22), intrinsic interVA and interVA at peak improvement (interVA(p)) varied widely between patients (from -83 to -15 ms and from -42 to +31 ms, respectively). However, the model predicted individual interVA(p) accurately (SD of +/-6 ms and +/-12 ms for LV dP/dt(max) and PP, respectively). At equal interVA, LV and BiV pacing produced equal hemodynamic response, but in 11 of 22 responders, BiV pacing reduced interVA insufficiently to reach the maximum hemodynamic response. LV pacing at short AV delay proved to result in better hemodynamics than predicted by the model, indicating that additional factors determine hemodynamics during LV preexcitation. Guided by a simple pathway model, interVA measurements accurately predict optimal hemodynamic performance in individual CRT patients.

Animals↗

PubMed2003

Comparative prospective randomized efficacy testing of different guiding catheters for coronary sinus cannulation in heart failure patients.

INTRODUCTION: The efficacy of different shapes of guiding catheters for coronary sinus (CS) cannulation was evaluated at implant of a cardiac resynchronization therapy device that required transvenous placement of a pacing lead in a coronary vein on the left ventricle. METHODS AND RESULTS: Comparative testing of 5 different guiding catheter shapes was attempted in 29 consecutive patients. Four newer guiding catheters were tested in a prospective randomized manner with a reference standard catheter always tested in the last place. All of the new catheters included a distal shape that consisted of a single curve or a compound set of curves at the catheter tip, followed by a catheter shaft design which fell into one of two classes: (1). straight shaft catheters and (2). curved shaft catheters. The curved shaft class of catheters, two new and one standard, achieved higher (16/23 (70%), 17/23 (74%) and 17/22 (77%)) CS cannulation success rates than the straight shaft class catheters ((13/23 (56%) and 12/23 (52%)). The pairing of two catheters, one from each class in a single patient, or both from the curved shaft class resulted in a combined CS cannulation success rate of up to 96%. Two of the catheters were more effective from a left hand insertion than from a right hand insertion site. CONCLUSIONS: The ability to switch between guiding catheters with different shapes and compound curves can improve the CS cannulation success rate. The selection of guiding catheters should be influenced by the intended use of the catheter either from the left or from the right hand side.

Cardiac Catheterization↗

PubMed2002

Acute effects of cardiac resynchronization therapy on left ventricular Doppler indices in patients with congestive heart failure.

BACKGROUND: Patients with heart failure frequently exhibit intraventricular conduction delays, which contribute to asynchronous contraction patterns and impaired hemodynamic performance. Cardiac resynchronization therapy (CRT) with biventricular (BV) and left ventricular (LV) pacing has been shown to improve both hemodynamic and clinical performance. This study investigated the effects of CRT on LV Doppler indices in these patients. METHODS AND RESULTS: Thirty-two patients with advanced heart failure (New York Heart Association class > or =III, QRS >120 milliseconds, PR interval >150 milliseconds) were studied 4 weeks after implantation of a CRT system. Doppler echocardiography was conducted in 3 separate CRT modes, right ventricular, LV, and BV stimulation at 3 different atrioventricular delays. CRT resulted in significant improvement of Doppler parameters such as filling time (FT, 313 +/- 111 milliseconds at baseline --> 363 +/- 154 milliseconds [BV], P <.05), aortic velocity time integral (AO(VTI) 23.2 +/- 7.4 cm at baseline --> 26.8 +/- 8.8 cm [LV], P <.05), and the myocardial performance index (MPI, 1.21 +/- 0.51 at baseline --> 0.85 +/- 0.34 [BV], P <.05). The most improvement was observed with LV and BV stimulation at short and intermediate atrioventricular delays (80-120 milliseconds), independent of ischemic or idiopathic origin. CONCLUSIONS: CRT improves hemodynamic performance in patients with heart failure with intraventricular conduction delays. Doppler echocardiography allows noninvasive evaluation of acute CRT effects in patients with heart failure. In particular, FT, AO(VTI), and MPI are useful parameters for noninvasive follow-up and optimization of pacing parameters.

Analysis of Variance↗