Electrocardiographic Changes During Normal Canine Puerperium

BATISTA PR; GOBELLO C; BARRENA JP; RE N; OLGUÍN S; CORRADA Y; ARIAS DO; BLANCO PG

Lisboa

Congreso; 25th ECVIM-CA CONGRESS, 2015; 2015

European College of Veterinary Internal Medicine

The canine cardiac conduction system is modified by anatomical and functional adaptations of the maternal heart during gestation. However, it is not clear if these changes persist or are modified after parturition. Therefore, the aim of this study was to describe canine electrocardiographic features during the course of normal puerperium.Twenty healthy pure-bred, 2?5 (3.85 ± 0.16) year-old, weighing 1.5?6 kg (3.55 ± 0.26) bitches were included in this study. All the animals whelped healthy puppies at term which were weaned on day 60 after parturition (day 0). All the dogs were electrocardiographically evaluated on days -3, 3, 10, 17, 24, 38, 52, and 80. Mean electrical axis (MEA; degrees), P wave amplitude (Pa; mv) and duration (Pd; ms), P-R interval (PR; ms), QRS complex amplitude (QRSa; mv) and duration (QRSd; ms), Q-T interval (QT; ms), and S-T segment (ST; mv) were calculated at 50 mm/s of velocity. The RR interval immediately preceding each complex was recorded and QT interval was corrected (QTc) by Van de Water formula [QTc = QT ? 0.087(RR ? 1000)]. Later, lead II was recorded at 25 mm/s to analyze heart rate (HR; bpm) and cardiac rhythm (CR; normal sinus rhythm or sinusarrhythmia). Values of HR, MEA, Pa, Pd, PR, QRSa, QRSd, QT, RR and QTc were analyzed by ANOVA for repeated measures followed by Tukey test. Cardiac rhythm was analyzed by chi square test (SPSS 17.0, SPSS Inc., Chicago, IL, USA). A p < 0.05 was considered significant. During the study period, HR (p < 0.01) and QTc (p < 0.01) progressively decreased, while RR (p < 0.01) and Pa increased (p < 0.01). QRS complex amplitude diminished in the second week after parturition and then increased during the following weeks (p < 0.01). Mean electrical axis shifted to the right during this period (p < 0.01). On day -3, most of the bitches presented normal sinus rhythm in contrast with day 3, in which most of the bitches presented sinus arrhythmia (p < 0.01). From day 10 onward, all the bitches showed sinus arrhythmia. P wave duration, PR, QRSd, QT and STremained unchanged during puerperium. It is concluded that most electrophysiological adaptive changes of canine gestation reverted during normal puerperium. The present study contributes to the understanding of canine cardiac physiology during this reproductive stage.