Alteration of pulmonary blood flow distribution in patients with congenital left to right cardiac shunt : pre- and postoperative study with macroaggregates of 99mTc-labeled human serum albumin

The pulmonary blood flow in 84 patients with left to right cardiac shunts was preoperatively and postoperatively examined by scintigram with macroaggregates of 99mTc-labeled human serum albumin. Lung biopsy was also performed in 28 patients. The regional pulmonary blood flow distribution curves obtained from perpendicular scintillation to the long axis of the right lung in the supine position were classified into 4 patterns (normal and types 1 to 3). The normal pattern displayed uniform distribution, however type 1 demonstrated a lack of upper corner in the curve. Type 2 showed 2 peaks (a lower peak in the upper and a higher peak in the lower part of the lung) with a dip between them. Finally only 1 peak in the lower part of the lung was manifest in type 3. The right Upper/Lower lung count ratio, R(U/L), expressed as the mean +/- standard deviation in each curve type was 0.82 +/- 0.12 (n = 23), 0.71 +/- 0.11 (n = 28), 0.6 +/- 0.08 (n = 17) and 0.58 +/- 0.18 (n = 16), respectively. The count ratios from the 3 abnormal types were statistically significant compared to the normal curve type (p < 0.01). In addition, the type 1 and 2 curves were significant compared to type 3 (p < 0.05-0.01). In patients under 3 years of age, lower R (U/L) count ratio expressed more severe pulmonary hypertension. Negative correlations were observed with the peak pulmonary/peak systemic pressure ratio, Pp/Ps, (r = -0.66, p < 0.01) and with the pulmonary vascular resistance index, PVRI, (r = -0.45, p < 0.01).