Differential coronary hemodynamics and left ventricular contractility in patients with syndrome X.
The relationship between coronary hemodynamics and left ventricular contractility was studied in 20 patients with syndrome X. Among them, 10 patients with a resting left ventricular ejection fraction (LVEF, by radionuclide method) equal to or greater than the mean value of the whole group (58%) were defined as having relative increased left ventricular contractility (group H), and another 10 patients with relatively normal contractility (50%</=LVEF<58%) were in group N. Eight subjects with normal contractility, exercise test and coronary angiograms served as the control (group C). Baseline great cardiac venous flow (GCVF) was higher in group N than in group H (P<0.05) and C (P<0.05), but similar between group H and C. After dipyridamole infusion (0.56 mg/kg, i.v., for 4 min), maximum GCVF was less in group H than in group N (P<0.001) and C (P<0.001), but similar between group N and C. As compared to group C (3.09+/-0.35), coronary flow reserve was reduced in both group H (2.34+/-0.55, P=0. 004) and N (2.40+/-0.36, P=0.001). In all syndrome X patients, resting LVEF was negatively correlated to baseline GCVF (P=0.026) and tended to be positively correlated to baseline coronary vascular resistance (P=0.057). Thus, coronary hemodynamics was altered with left ventricular contractility in syndrome X patients. In these patients, coronary flow reserve was similarly reduced with different underlying mechanisms. The limited increase of GCVF after dipyridamole infusion suggests impaired coronary microvascular dilation capacity in patients with relatively increased left ventricular contractility and the increase of baseline GCVF in those with normal contractility is more likely due to an altered basal myocardial metabolism.
Chen
J W
JW
Division of Cardiology, Department of Medicine, Veterans General Hospital, Taipei, Taiwan.
Hsu
N W
NW
Ting
C T
CT
Lin
S J
SJ
Chang
M S
MS
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001481:Basal Metabolism; D006328:Cardiac Catheterization; D017023:Coronary Angiography; D003326:Coronary Circulation; D004176:Dipyridamole; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D017566:Microvascular Angina / Q000378:metabolism / Q000503:physiopathology*; D008875:Middle Aged; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism; D015635:Radionuclide Ventriculography; D014665:Vasodilator Agents; D016277:Ventricular Function, Left
D014665:Vasodilator Agents; D004176:Dipyridamole