Influence of blood viscosity on circulatory parameters determined by first-pass radionuclide angiocardiography in cor pulmonale.

First-pass radionuclide angiocardiography (FPRNA) with 99mTc-albumin was performed in 19 patients with cor pulmonale. Pulmonary circulation time (PCT), mean transit time (MTT), pulmonary stagnation index (PSI) were calculated from the time-activity curves for the estimation of cardiopulmonary circulation. Whole blood viscosity (WBV), plasma viscosity (PV) and hematocrit (HTC) were also measured on the same day. Significant prolongation of all parameters was observed (WBW: 5.04 +/- 1.19 mPas; PV: 1.36 +/- 0.17 mPas; HTC: 47.6 +/- 2.37%; PCT: 7.10 +/- 2.15 s; MTT: 9.33 +/- 4.11 s; PSI: 1.30 +/- 0.37) in patients with cor pulmonale. Significant positive correlations were found between PCT and WBV (r = 0.552; 0.001 < P < 0.01), MTT and WBV (r = 0.34; P < 0.05), furthermore between PCT and HTC (r = 0.356; P < 0.05). The results suggest that hemorheological parameters may influence the results of FPRNA, therefore, they should be determined in addition to the radionuclide study.