The aim of our study was to analyse electromechanical time intervals in feline hearts in healthy
cats and cats with cardiomyopathy. We included 29 cats, 12 of which were healthy and 17 of
which had cardiomyopathy. Cats were examined clinically, echocardiographically, and an
electrocardiogram (ECG) with simultaneous phonocardiogram (PCG) was recorded. We used
a pilot PCG device built from an acoustic stethoscope, a microphone and a smartphone. We
recorded the ECG with a 12-lead ECG device connected to a personal computer. For
synchronization purpose of the ECG with the PCG we developed a synchronization device that
generates both acoustic and electrical signals with the push of a button. Our pilot PCG device
synchronized to ECG proved useful for evaluating the electromechanical activity of the feline
heart. We measured electric, electromechanical, and mechanical durations: QRS complex, QT
interval (electrical systole), electromechanical activation time (EMAT or QS1 interval), QS2
interval (electrical and mechanical systole), and electromechanical window (EMW) interval.
We normalized the electromechanical durations to the cardiac cycle (RR interval) and
calculated the corrected QT interval (QTc) with four different formulas. Measured
electromechanical durations did not differ significantly between the two groups, however the
intervals corrected to heart rate QRS/RR, QT/RR, EMAT/RR, QS2/RR, and S1S2/RR were
significantly longer in cats with cardiomyopathies than in healthy cats, suggesting that the heart
of cats with cardiomyopathies takes longer in the cardiac cycle to depolarize and repolarize and
to generate a pressure high enough to close the mitral valve than the unaffected heart of healthy
cats.
|
