Recognition of congestive heart failure (CHF) in dyspnoeic cats is crucial for correct intervention. The pulmonary vein (PV) to pulmonary artery (PA) ratio (PV/PA) has been proposed as an index that might help discriminate dogs in CHF but has never been studied in cats. We sought to determine reference intervals for various, previously published, PV and PA variables in healthy cats. We then examined these variables in cats with subclinical and clinical (CHF) cardiomyopathies to determine the diagnostic utility in identifying CHF.

We prospectively enrolled 99 cats: 51 healthy cats, 24 subclinical cardiomyopathic cats, and 24 cardiomyopathic cats with CHF. PV and PA were measured at the minimal and maximal diameters from M-mode images obtained from a modified right parasternal long axis view. Aorta and left atrium were measured from the right parasternal short axis just after the end of systole.

Median PV_min/PA_min in healthy cats was approximately 0.51 and PV_max/PA_max was 0.67. The median distensibility of the vessels was 23% for ΔPA and 41% for ΔPV. Several variables (PV_max/PA_max, PV_max/Ao and PV_min/Ao) increased incrementally between all 3 groups (p<0.0001). Cats with CHF had a larger PV_min/PA_min than subclinical and healthy cats (p<0.0001). When evaluating diagnostic performance of these variables (using only cardiomyopathic cats with or without CHF), PV_min/PA_min and PV_min/Ao had 100% specificity and 84% and 80% sensitivities, respectively. By comparison, LA/Ao had 71% specificity and 88% sensitivity.

Our study provides reference values for PV and PA variables in cats. Moreover, PV/PA variables performed better than LA/AO in discriminating cardiomyopathic cats with and without CHF.

Disclosures

No disclosures to report.