The increasing prevalence of obesity worldwide is a major threat to global health. Cardiac structural and functional changes are well documented for obesity as well as for pregnancy, but there is limited literature on morbidly obese parturients. We hypothesized that there are both cardiac structural and functional differences between morbidly obese pregnant women and pregnant women of normal body mass index (BMI).
This prospective cross-sectional study was performed in 2 referral maternity units in Cape Town, South Africa, over a 3-month period. Forty morbidly obese pregnant women of BMI ≥40 kg·m−2 (group O) were compared to 45 pregnant women of BMI ≤30 kg·m−2 (group N). Cardiac structure and function were assessed by transthoracic echocardiography, according to the recommendations of the British Society of Echocardiography. The 2-sample t-test with unequal variances was used for the comparison of the mean values between the groups.
Acceptable echocardiographic images were obtained in all obese women. Statistical significance was defined as P < .0225 after applying the Benjamini–Hochberg correction for multiple testing. Mean (standard deviation) mean arterial pressure was higher in group O (91 [8.42] vs 84 [9.49] mm Hg, P < .001). There were no between-group differences in heart rate, stroke volume, or cardiac index (84  vs 79  beats·minute−1, P = .103; 64.4 [9.7] vs 59.5 [13.5] mL, P = .069; 2551  vs 2729  mL·minute−1·m−2, P = .156, for groups O and N, respectively). Stroke volume index was lower, and left ventricular mass was higher in group O (30.14 [4.51] vs 34.25 [7.00] mL·m−2, P = .003; 152  vs 115  g, P < .001). S′ septal was lower in group O (8.43 [1.20] vs 9.25 [1.64] cm·second−1, P = .012). Considering diastolic function, isovolumetric relaxation time was significantly prolonged in group O (73  vs 61  milliseconds, P < .001). The septal tissue Doppler index E′ septal was lower in group O (9.08 [1.69] vs 11.28 [3.18], P < .001). There were no between-group differences in E′ average (10.7 [2.3] vs 12.0 [2.7], P = .018, O versus N) or E/E′ average (7.85 [1.77] vs 7.27 [1.68], P = .137, O versus N). Right ventricular E′/A′ was lower in group O (1.07 [0.47] vs 1.29 [0.32], P = .016).
Cardiac index did not differ between obese pregnant women and those with normal BMI. Their increased left ventricular mass and lower stroke volume index could indicate a limited adaptive reserve. Obese women had minor decreases in septal left ventricular tissue Doppler velocity, but the E/E′ average values did not suggest clinically significant diastolic dysfunction.
From the *Department of Anaesthesia and Perioperative Medicine, University of Cape Town and Groote Schuur Hospital, Cape Town, South Africa
†Department of Anaesthesia, University Hospital Basel, Basel, Switzerland
‡Department of Cardiology, University of Cape Town and Groote Schuur Hospital, Hatter Institute for Cardiovascular Research in Africa, Cape Town, South Africa
§Biostatistics Unit, South African Medical Research Council, Cape Town, South Africa.
Published ahead of print 8 May 2018.
Accepted for publication May 8, 2018.
Funding: This work was funded by a travel grant given to the principal investigator by the Obstetric Anaesthetists’ Association.
The authors declare no conflicts of interest.
Reprints will not be available from the authors.
Address correspondence to Bigna S. Buddeberg, MD, University Hospital Basel, Spitalstrasse 21, Basel 4056, Switzerland. Address e-mail to firstname.lastname@example.org.