Increased normalized pulmonary transit times and pulmonary blood volumes in cardiomyopathic cats with or without congestive heart failure.

OBJECTIVES: To estimate heart rate-normalized pulmonary transit times (nPTTs) in cardiomyopathic cats with or without congestive heart failure (CHF). To assess potential associations of echocardiographic variables and nPTT and to evaluate nPTT as a test for the presence of CHF.

ANIMALS: Forty-eight privately owned cats.

METHODS: nPTT was measured using echocardiography and the ultrasound contrast media SonoVue(®) in 3 groups of cats: healthy cats (group 1), cats with cardiomyopathy (CM) but without CHF (group 2), and cats with CM and CHF (group 3). Interrelations between pulmonary blood volume (PBV), nPTT, stroke volume (SV), and echocardiographic variables were investigated by means of linear univariate and multivariate analysis.

RESULTS: Median nPTT values in group 1, group 2, and group 3 were 3.63 (interquartile range [IQR], 3.20-4.22), 6.09 (IQR, 5.0-7.02), and 8.49 (IQR, 7.58-11.04), respectively. Values were significantly different between all 3 groups. Median PBVs in group 1, group 2, and group 3 were 27.94 mL (IQR, 21.02-33.17 mL), 42.83 mL (IQR, 38.46-50.36 mL) and 49.48 mL (IQR, 38.84-64.39 mL). SV, PBV, and shortening fraction <30% were significant predictors of nPTT. nPTT and left atrial to aortic root (LA:AO) ratio, not SV, were the main predictors of PBV.

CONCLUSION: nPTT may be useful as a test for the presence of CHF in cats with CM and as a measure of cardiac performance. nPTT and LA:AO ratios predict CHF with equal accuracy. Increased PBV is significantly associated with higher nPTT and LA:AO ratios.