Quantification of left ventricular performance during transient coronary occlusion at various anatomic sites in humans: a study using tantalum-178 and a multiwire gamma camera.

To study the functional significance of transient coronary occlusion on systolic and diastolic left ventricular function relative to the anatomic site of occlusion, first-pass radionuclide angiography with a mobile multiwire gamma camera using tantalum-178 (dose activity less than or equal to 84 mCi/elution) was performed in 46 patients undergoing balloon coronary angioplasty. First-pass images were acquired immediately before angioplasty and during the last 30 s of a 60-s balloon inflation in 23 left anterior descending arteries, 18 right coronary arteries, 8 circumflex arteries and 3 diagonal coronary arteries. Occlusion of the left anterior descending artery resulted in significant decreases in left ventricular ejection fraction (54.6 +/- 12.7% to 32.3 +/- 10.6%, p = 0.0001) and peak filling rate (2.48 +/- 0.68 to 1.75 +/- 0.64 end-diastolic volumes/s, p = 0.0001), accompanied by severe abnormalities in regional function and left ventricular dilation. Right coronary artery occlusion caused inferior hypokinesia, but did not significantly change left ventricular ejection fraction (48.5 +/- 12.4% vs. 45.8 +/- 12.5%, p = NS) or peak filling rate (2.05 +/- 0.81 vs. 2.09 +/- 0.81 end-diastolic volumes/s, p = NS). Circumflex artery occlusion resulted in mild wall motion deterioration and a borderline decrease in ejection fraction (54.7 +/- 11.4% to 50.5 +/- 12%, p = 0.057). Diagonal artery occlusion did not cause significant changes in left ventricular ejection fraction or filling rate. The decrease in left ventricular ejection fraction during coronary occlusion was 9 +/- 25% and 27 +/- 22%, respectively, in those arteries with and without collateral supply (p = 0.052). These data provide strong evidence for the critical importance of the left anterior descending artery and the secondary role of the other coronary arteries in maintaining global systolic and diastolic left ventricular function and suggest a protective role of collateral vessels during coronary occlusion.