Background and objective: During pregnancy many substantial changes occur in the cardiovascular system. Aim of this study was to examine how physiological preload alterations influence left ventricular haemodynamic parameters.
Patients and methods: During the 9th, 24th and 33rd weeks of pregnancy and 8 weeks after childbirth 36 patients underwent echocardiographic studies. 36 young not pregnant women (25 +/- 7 years) served as controls. The following Doppler echocardiographic parameters were measured: peak early diastolic flow velocity (VE, ms); acceleration (AT; ms) and deceleration time (DT; ms) of flow velocity in early diastole; peak late diastolic flow velocity (VA; m/s) and isovolumetric relaxation time (IVRT; ms). In all women the left ventricular muscle mass index (LVMMI), fractional shorting (FS; %) and the ratio between septum and posterior ventricular wall were calculated.
Results: During pregnancy all women showed an elevation of the left ventricular muscle mass index (LVMMI: from 66 +/- 6 to 100 +/- 9 g/m2; p < 0.01) and a decrease of fractional shortening (FS: from 38 +/- 4 to 31 +/- 3%). All patients developed a relevant diastolic dysfunction: reduced early diastolic flow velocity (VE: from 0.89 +/- 0.11 to 0.83 +/- 0.19 m/s; P < 0.01), reduced E/A ratio (1.7 +/- 0.4 to 1.2 +/- 0.4; P < 0.01), prolonged IVRT (72 +/- 12 to 114 +/- 12 ms; P < 0.01) and deceleration time (DT: to 189 +/- 17 to 227 +/- 18 ms; P < 0.01). Eight weeks after childbirth all parameters of left ventricular systolic and diastolic functions were normal.
Conclusion: Preload alterations during normal pregnancy lead to reversible physiological left ventricular hypertrophy. Furthermore, we found a short-time reduction of systolic function just before childbirth and a significant alteration of the left ventricular diastolic filling pattern (abnormal relaxation pattern). While left ventricular systolic function was normal in all patients one week after childbirth, left ventricular hypertrophy and left ventricular diastolic dysfunction persisted for nearly two months.