Determination of ventricular isovolemic contraction solely by means of pulse contour analysis

Abstract

It has been shown that the heart influences the arterial pulse contour before the aortic valve opens and aortic systole starts. In earlier work we suggested that the start of the isovolemic contraction period could be identified in the aortic and carotid arterial pressure waveform as the start of a temporary pre-systolic pressure increase (ADICS, aortic determined isovolemic contraction start), and presented the coronary retrograde flow as the most likely origin. In our current work we have shown that in 11 pigs this ADICS occurs significantly later than left ventricular systolic foot (LV systolic foot: 31.9±22.9ms, ADICS: 47.2±26.1, both relative to R-top ECG, difference inter-animal mean ± SD: 15.3 ± 6.3ms, p<0.001). Minimum pre-systolic coronary flow occurred 90.1±23.1ms after the R-top of the ECG, indicating that this flow is not the cause of the pre-systolic pressure increase, as aortic valve opening occurred shortly after this minimum flow (96.2±22.7 ms after the R-top of the ECG). Indeed, despite briefly occluding LAD, LCX and RCA coronary arteries, the pre-systolic pressure increase remained present in the aortic pressure waveform. For 8 pigs, an early peak in LV dP/dt coincided with the ADICS. Combining this observation with the LV pressure at which ADICS occurs (29.3±7.9mmHg), we propose that the abrupt closure of the mitral and tricuspid valve causes the pre-systolic aortic pressure increase.