Effect of cold stress on coronary sinus blood flow in patients with scleroderma.

The mechanism of cardiac involvement in scleroderma is not known. Histologic studies of the myocardium in patients who died of scleroderma revealed that half had myocardial damage. Characteristic involvement ranges from focal contraction-band necrosis to diffuse fibrosis despite the absence of obstructive coronary artery disease of the major epicardial vessels. These findings suggest that scleroderma heart disease might result from episodic reduction of coronary blood flow due to abnormalities of coronary vasomotor tone. Studies using cold pressor thallium 201 myocardial perfusion scans support this hypothesis. Our study measured coronary blood flow during hand immersion in ice water at cardiac catheterization to determine whether patients with scleroderma had an abnormal coronary blood flow response. Coronary sinus blood flow was measured using a thermodilution method. Five patients with scleroderma were compared with 5 control subjects. All patients and controls had normal coronary angiograms. The coronary blood flow at baseline in the scleroderma and the control group (130 +/- 33 mL/min and 86 +/- 27 mL/min, respectively) was not significantly different. During the cold pressor test, both groups had a small, insignificant increase in coronary blood flow from baseline to 60 seconds (130 to 144 mL/min, scleroderma patients; 86 to 89 mL/min, control subjects). Our findings suggest that the cold pressor test does not cause an abnormal increase in coronary vasomotor tone or an absolute reduction in coronary blood flow in patients with scleroderma, as previously suggested by thallium 201 cold pressor studies.