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

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)