Quantitative analysis of narrowings of intramyocardial small arteries in normal hearts, hypertensive hearts, and hearts with hypertrophic cardiomyopathy.

To clarify the pathophysiologic role of intramyocardial small artery (IMSA) diseases in hypertrophied hearts, narrowings of the IMSA were quantitatively evaluated in 39 autopsied hearts, 10 from patients with typical hypertrophic cardiomyopathy (HCM), four from patients with HCM showing features mimicking dilated cardiomyopathy (DCM-like HCM), 10 from patients with hypertension, and 15 from normal adults. The relations of narrowings of the IMSA to myocytic hypertrophy, myocardial fiber disarray, and fibrosis were also examined. The external caliber and the ratio of the luminal area to the total vascular area (percent luminal area, % lumen) were calculated by an image analyzer in 85 to 203 IMSAs from each patient. The external calibers of the IMSAs were similar among groups of hearts with HCM, hypertensive hearts, and normal hearts but were greater in those with DCM-like HCM. The mean % lumen of the IMSAs was similarly reduced in the hearts with HCM (29 +/- 5% in the ventricular septum and 31 +/- 5% in the left ventricular free wall) and in hypertensive hearts (30 +/- 8% and 31 +/- 7%) compared with that in normal hearts (40 +/- 5% and 38 +/- 5%) and was the lowest in the ventricular septum of hearts with DCM-like HCM (17 +/- 3%). The mean % lumen of the IMSA was inversely correlated with heart weight (r = -.59), the mean size of myocytes (r = -.66 in the ventricular septum, r = -.63 in the free wall), and percent fibrotic area in the septum (r = -.68). The mean % lumen values of the IMSAs in the tissues with and without disarray in the hearts with HCM were similar. Thus IMSA disease is of pathophysiologic importance in patients with HCM, DCM-like HCM in particular, or with hypertension.