Case Scenario: Cesarean Section Complicated by Rheumatic Mitral Stenosis

CARDIAC disease in pregnancy remains an important etiology of maternal and fetal morbidity and mortality.1Estimates of the incidence of cardiac disease in pregnant patients in developed countries range from 0.2 to 3%.2,3Although the incidence of rheumatic heart disease (RHD) has decreased in developed countries, it still accounts for most of the cardiac disease-related maternal mortality in developing countries—as well as in immigrants to the United States from these nations.4Mitral stenosis is the most commonly acquired valve lesion encountered in pregnant women and is almost invariably caused by RHD. Pregnancy and the peripartum period represent a physiologic burden that may worsen symptoms in even moderate degrees of cardiac disease. Consequently, many women are first diagnosed with cardiac disease during pregnancy. The need to provide labor analgesia or anesthesia for a Cesarean section to a woman with cardiac disease is not infrequent and can be challenging. In this case scenario, we discuss the peripartum management of a patient with severe mitral valve disease.A 37-yr-old woman (gravida, 2; para, 1) with a history of Cesarean section delivery 16 yr earlier presented at 28 weeks gestational age with complete placenta previa, possible placenta accreta, and worsening dyspnea. Although the patient complained of dyspnea with moderate exertion before pregnancy (class II symptoms, New York Heart Association Functional Classification system; table 1), she was now unable to lie flat and even became dyspneic when speaking (class IV). Her symptoms improved with heart rate control using 25 mg metoprolol orally twice daily. Physical examination revealed an arterial blood pressure of 101/59 mmHg, a regular heart rate of 107 beats/min, and a respiratory rate of 22 breaths/min. There were diastolic and holosystolic apical murmurs, 2:6 and 3:6, respectively. The patient's lungs were clear to auscultation bilaterally, and she had mild pedal edema. Electrocardiogram showed sinus tachycardia and left atrial enlargement. Preoperative transthoracic echocardiogram revealed moderate to severe mitral stenosis, moderate to severe mitral regurgitation, and moderate pulmonary hypertension with estimated pulmonary artery systolic pressure of 54 mmHg. There was moderate tricuspid regurgitation. Left and right ventricular systolic function were normal.The patient was admitted to the hospital for observation and management. Multidisciplinary meetings were held to discuss her management and included cardiology, high-risk obstetrics, and cardiac surgery, as well as cardiac and obstetric anesthesiology. Multiple studies have shown that vaginal delivery is well tolerated in most patients with valvular heart disease.5Cesarean section is usually performed for obstetrical indications only. Because our patient had placenta previa, an elective repeat Cesarean section was planned at 36 weeks gestational age in a cardiac operating room with cardiac surgery and cardiopulmonary bypass capabilities on standby.As prophylaxis against acid aspiration, 30 ml sodium bicitrate was administered orally in the holding area. While American Society of Anesthesiologists standard monitors were placed, the patient was positioned in the left uterine displacement position. Fetal heart rate monitoring was performed by one of the obstetricians from the time of entry into the operating room until surgical site preparation. A left radial arterial catheter was placed. Because of the patient's preexisting pulmonary hypertension, the pulmonary artery was catheterized via the right internal jugular vein. The patient's initial systemic arterial blood pressure was 125/65 (mean 76) mmHg. Her heart rate was 105 beats/min. Initial pulmonary pressures were 90/50 (mean 62) mmHg. Central venous pressure was 14 mmHg with a prominent V wave. Although thermodilution cardiac output was not measured because of tricuspid regurgitation, initial calculated mixed venous oxygen saturation was 34%. Remifentanil (0.2 μg · kg−1· min−1) was started to attenuate the sympathetic response to laryngoscopy and intubation. General anesthesia was induced with etomidate, and succinylcholine was used for paralysis, which was administered in a rapid sequence fashion. Maintenance of anesthesia consisted of a remifentanil infusion (0.05–0.1 μg · kg−1· min−1), a low level of isoflurane (less than 0.5 minimum alveolar concentration), and vecuronium for muscle paralysis. Higher doses of inhalational agents were avoided to prevent uterine atony. Depth of anesthesia was monitored using bispectral index (Aspect Medical Systems, Norwood, MA) and values from 40–60 were maintained during the intraoperative period. The patient was ventilated using 100% oxygen. To optimize pulmonary vascular resistance, vigilant attention was paid to maintaining normocarbia.Additional monitoring consisted of transesophageal echocardiogram. In the midesophageal four-chamber view, characteristic features of RHD are seen (fig. 1A). Mitral valve leaflets were thickened and calcified with decreased mobility. Some calcification of the mitral valve annulus was seen as well. The addition of color flow doppler showed turbulence of antegrade flow through the stenotic valve in addition to severe regurgitation (fig. 1B). The midesophageal mitral commissural view demonstrated commissural fusion (fig. 2). Transmitral blood flow velocity using continuous-wave Doppler is presented in figure 3. The mean gradient across the mitral valve was 16 mmHg. Pressure half-time measurement was 154 ms, which corresponded to an estimated mitral valve area of 1.4 cm2. Three-dimensional ultrasound reconstruction of the mitral valve, viewed from the atrial side (“surgeon's perspective”), is presented in figure 4. The mitral valve is severely retracted with significant commissural fusion.Cesarean section was performed without complications. Apgar scores of the neonate were 4 at 1 min and 9 at 5 min. The baby required assisted ventilation for approximately 1 min. After delivery, 40 U oxytocin was administered intravenously in 2 h. No significant changes in arterial or pulmonary pressures, or in transesophageal echocardiographic examination, occurred during the procedure.At the conclusion of the procedure, the patient was extubated. She was initially monitored in the operating room after extubation to ensure normocarbia and stable pulmonary artery pressures. She was then transferred to the cardiac care unit for postoperative monitoring. Mixed venous oxygen saturation improved to 54% within 4 h after Cesarean section. The patient was discharged from the cardiac care unit on postoperative day 1 and from the hospital on postoperative day 5. She underwent mitral valve repair and tricuspid valve annuloplasty 4 months later.Normal pregnancy results in dramatic changes to the cardiovascular system (table 2). Pregnancy produces a 30–50% increase in blood volume and cardiac output with physiologic anemia as a result of a greater increase in blood volume than red cell mass.6–8The increase in cardiac output is primarily the result of an increase in stroke volume with a smaller contribution from an increase in heart rate. Pregnancy reduces systemic vascular impedance. Anemia decreases blood viscosity with resultant decrease in systemic vascular resistance.At the time of labor and delivery, pain and anxiety increase catecholamine release with resultant increases in heart rate, arterial blood pressure, and cardiac output.6–8Autotransfusion of up to 500 ml with each contraction increases preload and, hence, cardiac output.3After delivery, there is an additional increase in venous return as a result of autotransfusion from the contracting uterus as well as from the loss of fetal compression of the inferior vena cava.9Acute rheumatic fever is an immune-mediated, multisystem inflammatory disease that is a sequella of group A streptococcal infection.10The pathogenesis of acute rheumatic fever is believed to involve the triad of a genetically susceptible individual, infection with a rheumatogenic strain of group A streptococcus, and an aberrant host immune response.11Rheumatic fever is characterized by carditis, valvulitis, arthritis, chorea, erythema marginatum, and subcutaneous nodules. Although the long-term effects of acute rheumatic fever on most tissues are minimal, its effects on the heart may be devastating. Inflammation leads to neovascularization, which enables further recruitment of T cells, leading to granulomatous inflammation and the establishment of chronic RHD.12Carditis occurs in 30–80% of patients with acute rheumatic fever, and at least 60% of untreated patients develop chronic RHD.Due to its association with RHD, mitral stenosis is highly prevalent in developing countries. In India, the prevalence of RHD is 6:1,000 among school-aged children, which is in contrast to that seen in the United States, 0.05:1,000.13,14In Asia proper, the prevalence of RHD has been reported as being as high as 12:1,000.15If one extrapolates these data, there are currently 1.9–2.2 million cases of RHD in children aged 5–14 yr in Asia proper, with a total of 11–16 million cases. Others16have estimated approximately 15.6 million cases of RHD worldwide, with 80% of these cases in developing nations. More than 200,000 new cases of RHD and 180,000 RHD-related deaths occur each year in the developing world.In India, the mean ± SD age of presentation is 15.1 ± 4.4 yr old with approximately two-thirds of patients presenting with mitral stenosis.13Although mitral stenosis frequently follows rheumatic fever, fewer than half of patients with RHD remember contracting rheumatic fever. The persistent inflammatory and hemodynamic valvular injury from rheumatic fever contributes to the progression of the disease.17The valve area usually narrows 0.1–0.3 cm2per year; however, the rate of progression may be accelerated with repeated episodes of rheumatic fever.18In a retrospective cross-sectional study of 714 patients presenting for valvular surgery for RHD in Africa, 31% had pure mitral regurgitation, 38% had pure mitral stenosis, and 31% had mixed presentation.19Ongoing rheumatic activity was diagnosed in 47% of patients with pure mitral regurgitation and in 2% of patients with pure stenosis. Although regurgitation was the most common lesion in the first and second decades, the prevalence of stenosis increased with age.In general, mitral regurgitation is well tolerated by pregnant patients because the reduction in systemic vascular resistance reduces regurgitant flow. Mitral stenosis, however, is generally less well tolerated. In the normal adult, the mitral valve has an area of 4–6 cm2. Among patients who do not have mitral valvular stenosis, there are no clinically significant increases in transmitral valvular gradient due to pregnancy-induced increases in cardiac output. With worsening mitral stenosis, however, increases in blood volume and cardiac output associated with pregnancy are less well tolerated. When mitral valve area is reduced to less than 2.0 cm2, a pressure gradient develops across the mitral valve. The magnitude of this gradient depends on stenosis severity and the amount of blood flow across the valve. Thus, as cardiac output increases during pregnancy, the gradient across the diseased mitral valve increases. This increase in left atrial pressure is reflected back into the pulmonary venous circulation and increases the risk of pulmonary edema. Untreated, this progression results in pulmonary arterial hypertension that may lead to increases in right ventricular pressures and, possibly, to right ventricular failure.20The etiology of the pulmonary hypertension is usually passive and hence reversible after intervention; however, endothelial changes and vascular remodeling may affect its course.21Pulmonary hypertension is associated with extremely high maternal and fetal mortality.22A mitral valve area greater than 1.5 cm2usually does not cause symptoms at rest. However, as the severity of stenosis increases, patients develop decreased exercise tolerance, orthopnea, cough, paroxysmal nocturnal dyspnea, or pulmonary edema.23Furthermore, atrial arrhythmia associated with ventricular rate acceleration is a common cause of worsening symptoms. Although the clinical presentation of rheumatic mitral stenosis is usually associated with symptoms of congestive heart failure, patients may also present with hemoptysis and chest pain from pulmonary hypertension.21Overall maternal mortality associated with mitral stenosis has been reported at 1%, but this number increases to 7% with worsening symptoms.24Desai et al. 20found the most common complication to be pulmonary edema. The most significant risk factors for the prediction of maternal pulmonary edema were the severity of mitral stenosis, late antenatal presentation, moderate to severe symptoms outside of pregnancy, and cardiac disease diagnosed for the first time in the index pregnancy. Silversides et al. 25reported that pulmonary edema and arrhythmia were the most common maternal complications; prematurity and intrauterine growth retardation were the most common fetal complications. Both maternal and fetal complications are directly related to stenosis severity and prepregnancy New York Heart Association Functional Classification.5,25The most common etiology of mitral stenosis is RHD. Other rare (less than 1%) causes are congenital valvular stenosis, vegetations and calcifications of the leaflets, parachute mitral valve, and annular calcification. Generally, mitral stenosis is characterized by restricted leaflet movement, a reduced orifice, and diastolic doming.26In RHD, calcification of the valvular and subvalvular apparatus, as well as thickening, deformation, and fusion of the valvular leaflets at the commissures produce a characteristic fish mouth-shaped orifice. Chordal fusion and shortening may result in significant subvalvular stenosis. Other characteristics that may be associated with chronic mitral stenosis include an enlarged left atrium, spontaneous echo contrast or smoke (related to low velocity blood flow with subsequent rouleaux formation by red blood cells), thrombus formation, and right ventricular dilation.Because planimetry of the mitral valve orifice is not influenced by assumptions of flow conditions, ventricular compliance, or associated valvular lesions, it is used as the reference standard for the evaluation of mitral valve area in mitral stenosis.26This orifice opening is best visualized in the transgastric basal short axis view and is best measured mid-diastole; however, three-dimensional reconstruction may improve accuracy. Severe calcification of the mitral valve may interfere with mitral valve area determination and, in patients with significant subvalvular stenosis, underestimation of the degree of hemodynamic compromise may occur when determining mitral valve area by planimetry.26A transmitral Doppler spectrum is measured along the axis of transmitral blood flow, most often obtained in a midesophageal four- or two-chamber view.26Transmitral valve flow is characterized by two peaked waves of flow away from the transducer (fig. 3). The first wave represents early diastolic filling and the second wave represents atrial The gradient may be estimated using the pressure gradient 4 Because gradient is influenced by left atrial and ventricular diastolic the mean gradient is the clinical values obtained through this have high with obtained using a during cardiac with mitral valve opening during early there is a increase in transmitral flow, which decreases to during when the left atrial and ventricular pressures With mitral stenosis, a gradient the left and may be maintained for a amount of time (fig. 3). This pressure flow the left and the of this early transmitral flow. The rate of in velocity may be by its pressure half which is the time from the velocity to the time when the velocity has to half of its pressure The pressure half time is to the mitral valve valve area half of this is that it is of valvular The that the mitral valve is at least The of mitral regurgitation or regurgitation decrease the of pressure half-time for the determination of mitral of mitral stenosis is in table women with a of moderate to severe mitral stenosis, on the New York Heart Association Functional Classification or severe pulmonary hypertension, mitral or mitral valve surgery be before pregnancy to the need for gestational and to improve pregnancy pregnant patients who develop cardiac symptoms as a result of mitral stenosis, heart rate reduction with and of activity are the of To with uterine are However, be avoided in the early of pregnancy and with in the because of its association with fetal growth is no from clinical studies that is but the studies included a number of women and the was often not started in the first heart rate and arterial blood pressure be monitored frequently during with to and also be used because can fetal blood atrial can be used to control the rate of ventricular response and be to prevent patients with mitral stenosis who develop worsening or heart can be with in echocardiographic developed by et al. used to patients who may be of mitral valve are as shown in table 4. is on a echocardiographic is then as the of the for each a and with an echocardiographic of or less have the best results from a than is associated with increased incidence of scores of are less for but patients with subvalvular disease to have or mitral regurgitation and left atrial thrombus are to The is usually performed the of the second to the effects of to the complications include atrial systemic cardiac mitral regurgitation, uterine and it is not clear fetal and the during pregnancy be for patients with severe mitral stenosis who do not to Mitral valve surgery is for to who are not for because cardiovascular surgery during pregnancy is associated with fetal mortality in one of patient had no of RHD. She had dyspnea with exertion until late in the second In addition to moderate to severe mitral stenosis, she had moderate to severe mitral regurgitation, a not well to presentation, she was short of with but exercise improved with metoprolol With and of her pregnancy without She in sinus pregnancy, developing infrequent episodes of sinus tachycardia that to doses of the increase in transmitral gradient associated with clinically significant mitral stenosis, time for diastolic filling is to ensure heart rate is to diastolic filling low heart are The decrease in diastolic left ventricular filling time associated with pregnancy-induced tachycardia further increases left atrial hemodynamic in mitral stenosis is to tachycardia to optimize left ventricular diastolic filling The increase in transmitral gradient can be further during from pain and further decreases diastolic left ventricular filling from can also lead to Other hemodynamic are the of normal to high and decreases in systemic vascular resistance, which result in are tolerated. in case of hemodynamic the be to these hemodynamic be avoided as it may may stable with or no on of may provide additional without significant increases in heart rate, pulmonary are no which is in pregnant patients with mitral stenosis for labor analgesia or anesthesia for Cesarean section. of analgesia and however, is for reduction of peripartum maternal morbidity and that the of be is on the of pregnancy and its with the patient's lesion of the that have on peripartum care is Because in hemodynamic to occur for the first h after delivery, cardiovascular monitoring be maintained from the peripartum into the period to morbidity and is the of anesthesia in women with cardiac output. Although has the to or even the cardiovascular response to it also reduces systemic vascular resistance and cardiac a et a on anesthesia for obstetric patients with cardiac disease. In general, anesthesia is not for the pregnant patient with significant mitral a using of with monitoring of arterial and cardiac filling pressures may be even for the most severe cardiac of atrial may the of In these American Society of for the of anesthesia be to the risk of et for peripartum anesthesia for pregnant women with valvular disease. analgesia for vaginal delivery is best with anesthesia to hemodynamic analgesia increase in heart rate. The addition of to the of the analgesia without to the sympathetic may be administered to patients who sympathetic to be monitored to increases and decreases in monitoring may be required to patients for Cesarean section include or In general, an provide the least amount of hemodynamic anesthesia may provide stable the sympathetic associated with laryngoscopy and are by of agents or the intraoperative period as of anesthesia is required to tachycardia and General anesthesia the of control and the to transesophageal echocardiographic monitoring the A number of case have the of anesthesia with maternal and fetal are often for anesthesia in patients with severe valvular disease because have a on the cardiovascular system and provide In the case of Cesarean however, this result in respiratory is a that analgesia of rapid and short Remifentanil the placenta but to be and in and remifentanil has the to provide intraoperative hemodynamic and rapid maternal and from anesthesia and respiratory of the need to uterine doses of have to be In the present low doses of isoflurane were agents have been used in the present However, with these low we that the of less agents not have had a significant on in care and as mitral stenosis remains a for the pregnant woman and her clinical the management of mitral stenosis in pregnancy are on the of the and Although it has been demonstrated that can be performed in pregnant there are no from with Fetal growth retardation remains an important with with from rate control with to be but clinical studies may the minimum blood pressure required to also remains a improve low of is not has that need to be are against the of improved for the of the pregnancy and a decrease in the risk of the peripartum of pulmonary artery is The most for pulmonary artery by the American Society of that pulmonary artery be for patients and there is a high risk of significant hemodynamic and in there are and to the catheter and the from Although many to or in has been into for to even a for increased have been from patient to of and or studies are to patient and pulmonary artery can be used to improve and care be and a is for these patients a of the cardiac disease and the physiologic changes induced by pregnancy and Both management during pregnancy as well the and of delivery be and by the and, possibly, cardiac With this it is possible to have for and