Increased pulmonary transit times in asymptomatic dogs with mitral regurgitation.
Pulmonary transit time (PTT) normalized to heart rate (nPTT) is a measure of the pulmonary blood volume (PBV) to stroke volume ratio (PBV/SV). It is an index of cardiac performance. To determine the effect of compensated mitral regurgitation (CMR) and decompensated mitral regurgitation (DMR) caused by valvular endocardiosis on the index nPTT, we measured nPTT by first-pass radionuclide angiocardiography and ECG in 13 normal dogs, 18 dogs with CMR, and 13 dogs with DMR. PTT was measured as time between onset of appearance of activity at the pulmonary trunk and the left atrium. In the normal dogs, the relationship between PTT and mean R-R interval (mRR) was PTT = 4.08 x mRR + 0.15 (R2 = 0.71). Normal nPTT was 4.4 +/- 0.6 (SD) (range. 3.6-5.3). in CMR, 6.3 +/- 1.6 (SD) (range, 4.0-9.7). and in DMR, 11.9 +/- 3.4 (SD) (range, 8.0-18.8). The differences among all groups were significant. Heart rates were 110 +/- 22 bpm in normal dogs, 111 +/- 20 in dogs with CMR, and 144 +/- 18 in dogs with DMR (P < .001 for difference between DMR group and normal and CMR groups). Increased nPTT in CMR indicates preclinical heart pump dysfunction. Heart rate-normalized pulmonary transit times may be a useful index of heart function in mitral regurgitation.
Lord
Peter
P
Department of Clinical Radiology, Faculty of Veterinary Medicine, Swedish University of Agricultural Sciences, Uppsala, Sweden. peter.lord@klra.slu.se
Eriksson
Anders
A
Häggström
Jens
J
Järvinen
Anna-Kaisa
AK
Kvart
Clarence
C
Hansson
Kerstin
K
Maripuu
Enn
E
Mäkelä
Olli
O
D000790:Angiocardiography / Q000662:veterinary; D000818:Animals; D016275:Atrial Function / Q000502:physiology; D004283:Dog Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology*; D004285:Dogs; D004452:Echocardiography / Q000662:veterinary; D006325:Heart Atria / Q000000981:diagnostic imaging; D006339:Heart Rate; D006352:Heart Ventricles / Q000000981:diagnostic imaging; D008168:Lung / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008944:Mitral Valve Insufficiency / Q000000981:diagnostic imaging / Q000503:physiopathology*; D011652:Pulmonary Circulation / Q000502:physiology*; D011875:Radionuclide Angiography / Q000662:veterinary; D013318:Stroke Volume / Q000502:physiology; D016276:Ventricular Function