Myocardial blood flow in congestive and hypertrophic cardiomyopathy. Relationship to peak wall stress and mean velocity of circumferential fiber shortening

Abstract

Myocardial blood flow/unit mass (MBF) and the determinants of myocardial oxygen consumption were measured in seven control subjects (group I) and 15 patients (pts) with cardiomyopathy (CM), group II (group IIa congestive CM: 10 pts; group IIb hypertrophic CM: 5 pts). In group I left ventricular (LV) MBF was 64±8 (SD) ml/100g.min; it was significantly lower in IIa (45 ± 15 ml/100g. min, P <0.01) and IIb (39 ± 7 ml/100g.min, P <0.01). However, calculated total LV flow (LV mass x MBF) was increased in the two CM groups. In nine CM pts, LV MBF increased in response to atrial pacing from 41±7 to 63±13 ml/100g.min. In group IIa, calculated peak wall stress was normal (4.39±0.77 dynes/cm2 x 105) but mean velocity of circumferential fiber shortening (MVcf) was significantly reduced (0.53±0.18 vs 1.26±0.12 circum/sec, P <0.01). In IIb, MVcf was normal but peak stress was significantly reduced (2.80±0.75 vs 4.51±1.10 dynes/cm2 x 105, P <0.05). Multiple regression analysis based on all pts yielded, MBF = 16.9 MVcf + 9.30 Stress + 0.26 Heart Rate - 26.4, (r = 0.79). The data indicate that MBF is reduced in CM patients and the regression analysis suggests that MBF in these 22 pts with normal coronary arteriograms was determined largely by heart rate, peak stress, and ventricular performance.