Comparison of permanent left ventricular and biventricular pacing in patients with heart failure and chronic atrial fibrillation: prospective haemodynamic study.

OBJECTIVE: To compare clinical and haemodynamic variables between left ventricular and biventricular pacing in patients with severe heart failure; and to analyse haemodynamic changes during daily life and maximum exercise during chronic left ventricular and biventricular pacing. DESIGN: Prospective single blinded randomised study with crossover. SETTING: University hospital (tertiary referral centre). PATIENTS AND METHODS: 13 patients (mean (SD) age, 62 (6) years) with chronic atrial fibrillation, severe heart failure (mean ejection fraction 24 (8)%), and QRS prolongation of > or = 140 ms had His bundle ablation and installation of a pacemaker providing left ventricular and biventricular pacing. The pacemaker was equipped with a peak endocardial acceleration (PEA) sensor. The PEA pattern was used as a haemodynamic marker during exercise as it is highly correlated with left ventricular dP/dt. After a baseline period of right ventricular pacing, all patients had two months of left ventricular pacing and two months of biventricular pacing in random order. At the end of each phase, an echocardiogram, a haemodynamic analysis at rest and on exercise during a six minute walk test, and a cardiopulmonary exercise test were performed. RESULTS: PEA values were higher with left ventricular pacing (0.58 (0.38) m/s) and biventricular pacing (0.62 (0.24) m/s) than at baseline (0.49 (0.18) m/s) (p < 0.05). The six minute walk test showed similar performance in both pacing modes, but patients had more symptoms with left ventricular pacing at the end of the test (p = 0.035). On cardiopulmonary exercise testing, there was a greater increase in mean percentage variation of PEA with biventricular pacing than with left ventricular pacing (125 (18)% v 97 (36)%, respectively; p = 0.048) and better performance figures (92 (34) W v 77 (23) W; p = 0.03). CONCLUSIONS: During symptom limited and daily life exercise tests, chronic biventricular pacing provides better haemodynamic performance than left ventricular pacing. In heart failure patients with wide QRS complexes, the interventricular dyssynchronisation induced by left ventricular pacing may impair myocardial function during exercise.

Simultaneous analysis of heart rate variability and myocardial contractility during head-up tilt in patients with vasovagal syncope.

INTRODUCTION: The aim of this study was to evaluate simultaneously cardiac autonomic activity, through heart rate variability (HRV) analysis, and cardiac inotropic changes during head-up tilt (HUT) in patients with recurrent vasovagal syncope. METHODS AND RESULTS: Twelve subjects implanted with a permanent dual-chamber pacemaker for recurrent vasovagal syncope characterized by marked bradycardia were studied. The tip of the right ventricular electrode was equipped with a sensor that measured peak endocardial acceleration (PEA) as an index of myocardial contractility. RR interval and PEA signals were acquired simultaneously and processed in the time and frequency (low frequencies [LF] and high frequencies [HF] of RR signal) domain during early HUT (T1), late HUT, or before syncope (T2). In the six subjects with positive HUT: (1) Abnormal heart rate oscillations were evidenced at T1 and discriminated this group from the negative group (LF/HF decreased by 46% from supine to T1, but increased by 55% in the negative group; P < 0.01 positive vs negative HUT). (2) Gradual diminution of the HF component was associated with an increase in PEA index during HUT with a correlation between PEA/RR interval (R = -0.8, P < 0.001), PEA/HF components (R = -0.6, P < 0.05). (3) Sympathetic stimulation responsible for changes in both HRV and PEA parameters occurred immediately before the faint (LF/LF+HF: 0.6 +/- 0.2 to 0.8 +/- 0.09; P < 0.05 T2 vs T1; PEA: 0.62 +/- 0.10G to 0.83 +/- 0.22G; P < 0.01 T2 vs T1). CONCLUSION: Our findings showed that a homogeneous subgroup of patients with recurrent vasovagal syncope and positive HUT exhibited abnormal cardiac autonomic and inotropic responses to an orthostatic stimulus. Continuous changes over time of HRV and PEA parameters highlight the dynamic behavior of the mechanisms leading to syncope.

Validation by serial standardized testing of a new rate-responsive pacemaker sensor based on variations in myocardial contractility.

AIMS: Preliminary studies have shown that peak endocardial acceleration (PEA), measured by a micro-accelerometer at the right ventricular apex, is highly correlated with left ventricular contractility (dp/dt max). Furthermore, changes in PEA are closely correlated with sinus node rate changes during exercise and during pharmacological interventions. Peak endocardial acceleration has, therefore, been used to drive a rate-responsive DDD pacemaker. This study compared the chronotropic performance of such devices implanted in 14 patients suffering from chronotropic incompetence with that observed in 18 control subjects in normal sinus rhythm. METHODS AND RESULTS: Five standardized daily life activities (hall walk, climbing up and down stairs, squatting and hyperventilation) and two types of exercise (Bruce treadmill protocol and bicycle ergometry) were performed in a random order after individual programming of each pacemaker. For each test, a correlation coefficient was calculated between changes in PEA and variations in paced rate, between instantaneous variations in heart rate monitored by telemetry and continuous measurement of heart rate by the pacemaker, and between sensor-driven rate in patients and normal sinus rhythm in controls. The variations in paced heart rate were closely correlated with those observed in subjects with normal sinus rhythm, and proved to be sensitive, specific, rapid and independent of the type of exercise. After optimal programming of the sensor, PEA modulates the heart rate as expected during normal sinus rhythm. CONCLUSIONS: In this study, a single PEA sensor successfully restored chronotropic response in a population of paced patients with severe chronotropic incompetence. Peak endocardial acceleration can be monitored on a beat-to-beat basis, in parallel with heart rate, and the pacemaker can be accurately programmed with a single exercise test.

Hemodynamic assessment of right, left, and biventricular pacing by peak endocardial acceleration and echocardiography in patients with end-stage heart failure.

Multisite ventricular pacing acutely improves the hemodynamic status in heart failure, though longer-term observations require invasive procedures. The hemodynamics of multisite ventricular pacing were assessed by echocardiography and peak endocardial acceleration (PEA) measured by a pacemaker sensor. PEA variations are highly correlated with those of dP/dt. Thirteen end-stage heart failure patients (left ventricular ejection fraction < 0.30) with a QRS > or = 140 ms received a DDD PEA sensor-driven pacemaker allowing right (RV), left (LV) and biventricular (BV) pacing. Ten days after implantation, standard echocardiographic parameters and variations in PEA were measured after 20 minutes at each pacing mode. The aortic systolic preejection time interval was statistically comparable between RV and LV pacing (218 +/- 24 vs 219 +/- 34 ms; P = NS), and significantly shorter with BV pacing (198 +/- 27 ms; P = 0.013). Aortic ejection duration was nonsignificantly shorter during BV pacing than during LV pacing (-.061, P = 0.09). The aortic velocity time integer increased during LV pacing versus RV pacing (+21%, P < 0.05) and during BV pacing versus RV pacing (+37%, P = 0.05). As a result, the values of the PEA variations over a 15-minute period were significantly greater during LV pacing and BV pacing versus RV pacing (+43%, P < 0.05, and +38%, P = 0.05, respectively) and were statistically comparable between BV pacing and LV pacing (9% for LV pacing, P = NS). During various ventricular pacing configurations, PEA measurements were consistent with echocardiographic data, showing comparable hemodynamic effects of BV and LV pacing. The PEA sensor is a promising tool for long-term hemodynamic monitoring and serial evaluation of the effects of multisite ventricular pacing in heart failure patients.