Myocardial perfusion reserve in adults with cyanotic congenital heart disease

1 Department of Molecular and Medical Pharmacology and the 2 Ahmanson/University of California, Los Angeles, Adult Congenital Heart Disease Center, David Geffen School of Medicine at The University of California, Los Angeles, California Submitted 1 January 2004 ; accepted in final form 16 June 2005 In patients with cyanotic congenital heart disease (CCHD), a right-to-left shunt results in systemic hypoxemia. Systemic hypoxemia incites a compensatory erythrocytosis, which increases whole blood viscosity. We considered that these changes might adversely influence myocardial perfusion in CCHD patients. Basal and hyperemic (intravenous dipyridamole) perfusion measurements were obtained with [ 13 N]ammonia positron emission tomographic imaging in left (LV) and right (RV) ventricular and septal myocardium in 14 adults with CCHD [age: 34.1 yr (SD 6.5)]; hematocrit: 62.2% (SD 4.8)] and 10 healthy controls [age: 34.1 yr (SD 6.5)]. In patients, basal perfusion measurements were higher in LV [0.77 (SD 0.24) vs. 0.55 ml·min –1 ·g –1 (SD 0.09), P < 0.02], septum [0.71 (SD 0.16) vs. 0.49 ml·min –1 ·g –1 (SD 0.09), P < 0.001], and RV [0.77 (SD 0.30) vs. 0.38 ml·min –1 ·g –1 (SD 0.09), P < 0.001]. However, basal measurements normalized for the rate-pressure product were similar to those of controls. Calculated oxygen delivery relative to rate-pressure product was higher in the patients [2.2 (SD 0.8) vs. 1.6 (SD 0.4) x 10 –5 ml O 2 ·min –1 ·g tissue –1 ·(beats·mmHg) –1 in the LV, P < 0.05, and 2.0 (SD 0.7) vs. 1.4 (SD 0.3) x 10 –5 ml O 2 ·min –1 ·g tissue –1 ·(beats·mmHg) –1 in the septum, P < 0.01]. Hyperemic perfusion measurements in CCHD patients did not differ from controls [LV, 1.67 (SD 0.60) vs. 1.95 ml·min –1 ·g –1 (SD 0.46); septum, 1.44 (SD 0.56) vs. 1.98 ml·min –1 ·g –1 (SD 0.69); RV, 1.56 (SD 0.56) vs. 1.65 ml·min –1 ·g –1 (SD 0.64), P = not significant], and coronary vascular resistances were comparable [LV, 55 (SD 25) vs. 48 mmHg·ml –1 ·g·min (SD 16); septum, 67 (SD 35) vs. 50 mmHg·ml –1 ·g·min (SD 21); RV, 59 (SD 26) vs. 61 mmHg·ml –1 ·g·min (SD 27), P = not significant]. These findings suggest that adult CCHD patients have remodeling of the coronary circulation to compensate for the rheologic changes attending chronic hypoxemia. heart defects congenital; myocardial perfusion; positron emission tomography; myocardial perfusion reserve Address for reprint requests and other correspondence: R. C. Brunken, Dept. of Molecular and Functional Imaging/Gb3, Cleveland