MEASUREMENTS OF HUMAN CORONARY VASCULAR IMPEDANCE

The aim of this study was to develop a method of measuring human coron ary circulation impedance in a clinical setting. The authors measured coronary flow reserve (CFR) in 27 patients with chest pain and normal coronary arteries. A Judkins-style, 8F Doppler-tipped angiographic cat heter was positioned in the left coronary ostium. Resting coronary flo w velocity (RFV) and response to a hyperemic 12 mg intracoronary dose of papaverine (PFV) were measured. The signals were recorded by a reco rder connected to a microprocessor with analogue-to-digital converter and a maths coprocessor. Using this the authors could obtain values fo r impedance at RFV (IR) and at PFV (IP). The CFR was defined as the ra tio: PFV/RFV. An impedance index (II) was obtained as the ratio of cor onary vascular impedance at peak hyperemia to the impedance at rest. T he CFR was 3.2 +/- 1.2 and the II was 0.33 +/- 0.11. There was a stron g inverse correlation between the CFR and the II (r = -0.9). The autho rs conclude that this new approach may allow a further insight into th e coronary pathophysiology and may become useful in clinical cardiolog y, eg, in the assessment of heart transplant and Syndrome X patients.