Physiologic changes during pregnancy can deteriorate or improve patients’ hemodynamic status in the setting of valvular heart disease. There are sparse data regarding the effect of pregnancy on valve hemodynamics in normal pregnant women with known valvular heart disease. In a prospective study from July 2014 to January 2016, a total of 52 normal pregnant women who had mitral stenosis, aortic stenosis, or a history of mitral valve or aortic valve replacements were assessed. All patients underwent echocardiographic examinations and hemodynamic parameters were measured for both the mitral valve and aortic valve at first, second, and third trimesters. The parameters included mean gradient, peak gradient, mean gradient/heart rate, peak gradient/heart rate, pressure halftime, dimensionless velocity index, and valve area. Although most hemodynamic parameters (i.e., mean gradient, peak gradient, mean gradient/heart rate, and peak gradient/heart rate) increased approximately 50% from first to second trimester and first to third trimester (p <0.05) but those remained stable at third compared with second trimester (p >0.05). The ratio of changes between trimesters for valve area and dimensionless velocity index were comparable. No clinical decompensations were observed except for 3 and 7 cases of deterioration to functional class II at second and third trimesters, respectively. In conclusion, during a full-term and uncomplicated pregnancy, mitral and aortic valve gradients increase without significant changes in valve area that are more marked between the second and first trimester than between the third and second trimester.
Cardiovascular disease involves approximately 1% to 3% of pregnant women accounting for 10% to 15% of maternal mortality. The most challenging heart diseases during pregnancy include valvular heart disease which can lead to life-threatening complications for both mother and baby. In industrialized countries, congenital heart diseases are the main origins of valvular heart disease, whereas in developing countries such as Iran, rheumatic valvular disease dominates instead. Several physiologic changes (e.g., increases in cardiac output, stroke volume, and heart rate or decrease in vascular resistance) occur during normal pregnancy, which can either worsen patient’s condition in the setting of valve stenosis or improve patients’ hemodynamic status in valvular regurgitation. However, according to the American College of Cardiology/American Heart Association guidelines, follow-up by transthoracic echocardiography (TTE) is indicated in pregnant women with known or suspected valvular heart disease and those with prosthetic valves. To ameliorate our understanding of such a complex situation in our clinical daily practice, in a prospective study, we determined the hemodynamic changes of heart valves measured by TTE at the end of each trimester in normal pregnant women who suffered from mitral or aortic valve diseases.
Methods
In a prospective study, all consecutive pregnant women with valvular heart diseases or with a history of heart valve replacement who visit our obstetrics clinic in Rajaie Cardiovascular Medical and Research Center were prospectively assessed from July 2014 to January 2016. Study patients comprised pregnant women who had mitral stenosis (MS), aortic stenosis (AS), or a history of mitral valve or aortic valve replacements (MVRs or AVRs).
Exclusion criteria included pregnant women with AS associated with aortic pathologies, taking high dose β blockers and diuretics at baseline, New York Heart Association (NYHA) functional class >II at baseline. After entering the study, other cases were excluded because of worsening of functional class more than or equals to 2 classes compared with baseline condition, patients who needed valvular interventions, patients with intrauterine fetal death or abortion, and premature delivery. In addition, for patients with exertional dyspnea, some drugs were prescribed, including low doses of diuretics or β blockers; those with decompensated symptoms who underwent surgical or percutaneous interventions were also excluded.
MS was defined as mitral valve area <2 cm 2 which was measured by TTE. MS was categorized into 3 groups: (1) progressive MS with MV area of >1.5 cm 2 ; (2) severe MS with mitral valve area of 1 to 1.5 cm 2 ; and (3) very severe MS with mitral valve area of <1 cm 2 . According to the mean gradient of aortic valve, patients with AS were categorized into 3 groups: (1) mild AS with mean gradient <20 mm Hg; (2) moderate AS with mean gradient 20 to 39 mm Hg; (3) severe AS with mean gradient ≥40 mm Hg. Patients with MVR or AVR included those who underwent the implantation of bioprosthetic or mechanical valves.
All pregnant women were examined by TTE at 3 intervals, including 10 to 12 weeks at first trimester, 16 to 18 weeks at second trimester, and 28 to 32 weeks at third trimester (all dates were based on sonography report). Echocardiographic examinations were performed by a single operator using Doppler echocardiography and following parameters were measured for both the mitral valve and aortic valve at 3 intervals: (1) mitral valve mean gradient, mm Hg; (2) mitral valve mean gradient/heart rate; (3) mitral valve peak gradient, mm Hg; (4) mitral valve peak gradient/heart rate; (5) pressure halftime, ms (indicates the time during which both left atrium and left ventricle have equal pressure); (6) aortic valve mean gradient, mm Hg; (7) aortic valve mean gradient/heart rate; (8) aortic valve peak gradient, mm Hg; (9) aortic valve peak gradient/heart rate; and (10) left ventricle outflow tract velocity time index/aortic valve velocity time index, named dimensionless velocity index. Furthermore, the ratios of changing for all parameters from second to first trimester, third to first trimester, and third to second trimesters were calculated. In addition, for each of these groups, valve area was calculated using the following formula in the setting of MS or AS:
Stroke Volume Mitral or Aortic Valve VTI = ( LVOTD ) 2 × 0.785 × LVOT VTI Mitral or Aortic Valve VTI
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