Introduction

Pregnancy is associated with changes in cardiac function to support fetal development; few studies analyzed factors affecting this adaptation. Gestational cardiac changes assessment could elucidate cardiac adaptation process to large pregnancies for the expected greater circulating volume increase.

Objectives

To evaluate the effects of gestational age and fetus number on maternal cardiac function.

Methods

Nine healthy Great Dane bitches underwent standard M-mode and B-mode echocardiographic exam prior to (T0), 21-days (T1) after ovulation and within 7 days of predicted parturition (T2). After whelping, bitches were divided in 2 groups: small (<7 puppies) and large litters (>7 puppies). The effects of gestational age and fetus number on end-point-septal-separation (EPSS), left atrial to aortic root ratio (LA/Ao), sphericity index (SI), stroke volume (SV), heart rate (HR) and cardiac output (CO) were evaluated by ANOVA. The SV, CO and HR variation between groups at T2 vs T0 was calculated.

Results

During pregnancy, SV, HR and CO significantly increased (p<0.01). In large pregnancies, SV, HR and CO resulted in greater increase at T2 by 10.8%, 10.5% and 11.47%, respectively. No statistical difference was observed for EPSS, LA/Ao and SI.

Conclusions

This study confirms that maternal heart undergoes significant changes along pregnancy. Moreover, it demonstrates that in large pregnancies there is a higher increase in SV, CO and HR that probably reflects the greater cardiovascular work to support fetal development. Further investigations would assess whether different changes occur during large litter pregnancies in different age and breed bitches.

References

1.  Abbott. J Vet Cardio. 2010;12:123–128.

2.  Blanco, et al. Theriogenology. 2012;78:1235–4297.