Non-invasive study of dual chamber pacing by pulsed Doppler. Prediction of the haemodynamic response by echocardiographic measurements

Abstract

The increase in stroke volume with DDD compared with VVI pacing was measured at rest using pulsed Doppler echocardiography in 23 patients at a pacing rate of 70 beats min-1. Stroke volume was assessed by measuring the velocity integral of the flow at the aortic annulus using the apical five-chamber window. Pulsed Doppler echocardiography allowed determination of the least and most favourable AV delay haemodynamically. TVI was also measured at each nominal value of AV delay. The percentage increase in stroke volume was determined in every patient changing from VVI to optimum DDD pacing and was used as a measurement of the 'sensitivity' to optimum DDD pacing; the mean increase was 27 +/- 19%. The increase in stroke volume accompanying the change from DDD pacing with the least favourable to the optimum AV delay was also measured, and used as a measurement of 'sensitivity' to changes in AV delay; the mean increase was 23.7 +/- 16.3%. Clinical and standard echocardiographic parameters were studied in order to determine which variable might best identify the patients more likely to benefit from DDD pacing, and to identify those more sensitive to the AV delay setting. With respect to sensitivity to DDD pacing, three echocardiographic variables were selected by linear discriminant analysis from 11 clinical and echocardiographic variables. These were, in order of importance, left ventricular systolic diameter (LVSD), left ventricular wall thickness (LVWT) and left atrial size (LAS) which allowed the prediction of a good or a bad response to optimal DDD pacing with an accuracy of 91.3%.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrioventricular Interval Optimization and Exercise Tolerance

“…Hemodynamic benefits of dual chamber pacing including adaptation to sinus rhythm and maintenance of AV synchrony, [24][25][26][27][28] have been demonstrated by Doppler, 10,14,15,29,30 radionuclide, 31 and invasive 32 studies in patients with diverse underlying pathologies. 9,10,[33][34][35][36][37][38][39][40] Cardiac output may increase by nearly 30% in AV synchronous pacing compared to ventricular inhibited single chamber pacing.…”

“…5,40 A 21% difference in cardiac index between optimally and least favorably programmed AV intervals was observed in the current study, a finding consistent with previous reports. 9,14 Some patients were particularly sensitive to different AV interval settings with 50% changes in cardiac index noted between optimal and least favorable AV intervals (Table I, cases 1 and 2). Tremendous individual variability in response to different AV intervals settings has been previously reported.…”

“…While optimal AV intervals cannot be reliably predicted on the basis of clinical criteria alone, they may be determined by noninvasive testing. [9][10][11][12][13][14] However, it is not known if optimizing AV intervals at rest improves exercise capacity. Moreover, although rate adaptive AV interval shortening has been shown to improve hemodynamic parameters at increased heart rates, clinical benefits on exercise tolerance remain unclear.…”

The Acute Effect of Cardiac Pacing Mode on Endothelial Vasodilation: Prospective, Double‐Blind, Cross‐Over, Comparative Clinical Study

“…VVI pacing exerts complex hemodynamic alterations and cardiovascular reflexes that may affect endothelial function. Both invasive 11–13 and noninvasive 14–16 studies have consistently shown that VVI pacing causes a 10–53% decrease in resting cardiac output. This in turn leads to an increase in sympathetic tonus as reported by several authors.…”