Abstract 2515: Determinants of the Coronary Flow Velocity Waveforms in Aortic Stenosis
Background: Different haemodynamics are present in left ventricular hypertrophy (LVH) due to arterial hypertension and aortic stenosis (AS) and these can have different effects on the microvasculature. We explored this with wave intensity to
identify intracoronary waves determining the flow velocity waveform and
investigate the extravascular influences on these waves.
Methods: Thirty-one patients (mean age 63±12years, 18 female) with normal coronary arteries, ten had severe aortic stenosis, underwent simultaneous pressure and Doppler measurements in the left coronary arteries to derive wave intensity.
Results: In normal subjects, the microcirculatory waves accounted for the majority of the intra-coronary wave energy (54.7±6.0%), but in AS this rose to 74.1±10.7%, p<0.001. This resulted from larger absolute microcirculatory originating waves, both during microvascular compression (no valve disease: 1.4 [0.6 –3.2] x103Wm−2s−1 versus AS: 11.7 [5.4 –25.5] x103Wm−2s−1, p<0.001) and during microvascular relaxation (no valve disease: 14.0 [6.6 –18.0] x103Wm−2s−1 versus AS: 31.1 [20.4 – 47.4] x103Wm−2s−1, p<0.001). Left ventricular haemodynamic loading accounted for extent of compression wave (r=0.79, p<0.001) and diastolic microvascular relaxation wave was accounted for by reduced diastolic time (r=−0.62, p<0.001).
Conclusion: Coronary circulation in AS is even more dependent on distal-originating waves than it is in normals and this is in contrast to what is seen in LVH due to arterial hypertension. This is because the enhanced extravascular force overwhelms any local impairment within the microvasculature.