Stretch-Induced Compliance mechanism in pregnancy-induced cardiac hypertrophy and the impact of cardiovascular risk factors

Abstract

Introduction: Pressure-overload-induced hypertrophy compromises cardiac stretch-induced compliance (SIC) after acute volume overload (AVO). We hypothesized that SIC could be enhanced by physiological hypertrophy induced by pregnancy's chronic volume overload. This study evaluated SIC-cardiac adaptation in pregnant women with or without cardiovascular risk (CVR) factors. Methods: Thirty-seven (1st trimester, 1stT) and a separate thirty-one (3rd trimester, 3rdT) women (healthy or with CVR factors [obesity and/or hypertension and/or with gestational diabetes]) underwent echocardiography determination of left ventricular (LV) end-diastolic volume (LVEDV) and E/e' before (T0), immediately after (T1) and 15min after (T2; SIC) AVO induced by passive leg elevation. Blood samples for NT-proBNP quantification were collected before and after the AVO. Results: Acute leg-elevation significantly increased inferior vena cava diameter and stroke volume from T0 to T1 in both 1stT and 3rdT, confirming AVO. LVEDV and E/e' also increased immediately after AVO (T1) in both 1stT and 3rdT. SIC adaptation (T2-15min after AVO) significantly decreased E/e' in both trimesters, with additional expansion of LVEDV only in the 1stT. NT-proBNP increased slightly after AVO but only in the 1stT. CVR factors, but not parity or age, significantly impacted SIC cardiac adaptation. Conclusion: A distinct functional response to SIC was observed between 1stT and 3rdT, which was influenced by CVR factors. The LV of 3rdT pregnant women was hypertrophied, showing a structural limitation to dilate with AVO, while the lower LV filling pressure values suggest increased diastolic compliance.