Haemodynamic analysis of atrioventricular tachycardia.

The aim of the study was to delineate the influence of the ventriculo-atrial interval (VAI) in tachycardia with regard to the underlying heart disease. Haemodynamic studies were performed by the conductance catheter technique during paced tachycardia with a HR of 140, 160 and 180 beat.min-1 at various VAI in 10 patients; three with coronary heart disease (CHD), three with hypertensive heart disease (HHD) and four serving as controls. The influence of the VAI accounted for an overall change in cardiac index (CI) of 30 +/- 14%. Alterations in left ventricular peak systolic pressure (LVPSP) depending on VAI were significantly higher (P < 0.01) in CHD patients (32 +/- 9%) than in other groups (14 +/- 9% in the controls and 17 +/- 8% in HHD patients). The influence of VAI on left ventricular end-diastolic pressure (LVEDP) did not differ between the subgroups and accounted for a mean overall change of 32 +/- 14%. Atrial activation during the last third of the cardiac cycle led to the highest values of CI, LVEDP and LVPSP in the control group, whereas in HHD and CHD groups minimal values of CI were correlated with maxima of LVEDP and LVPSP. Conversely, with atrial activation during the medium third of the cardiac cycle minima of CI and LVEDP were observed in the controls, whereas in HHD and CHD patients the highest cardiac index coincided with the lowest LVEDP. Thus tachycardias have different haemodynamic effects depending on the nature of myocardial impairment and the timing of AV coupling.