Importance of transesophageal echocardiography in peripartum cardiomyopathy undergoing lower section cesarean section under regional anesthesia.

Peripartum cardiomyopathy is a relatively rare but life threatening disease. The etiology and pathogenesis of peripartum cardiomyopathy is generally centered upon viral and autoimmune mechanism. This case report describes the anesthetic management of a patient with term pregnancy suffering from dilated peripartum cardiomyopathy planned for cesarean section, successfully managed with epidural anesthesia after precipitate labour.

Introduction

Peripartum cardiomyopathy (PPC) is a relatively rare form of acute heart failure (HF) associated with pregnancy. The diagnosis presents a challenge as many full term parturients experience dyspnea, fatigue, and peripheral edema. Pearson et al.[1] published data on 27 patients with pregnancy-associated cardiomyopathy who presented in the peripartum period. These investigators coined the term “PPC” and defined diagnostic criteria on the basis of their patient's characteristics and available diagnostic tools at the time. These criteria included:

The development of HF in the last month of pregnancy or within 5 months of delivery;

The absence of a determinable etiology for HF; and

The absence of demonstrable heart disease before the last month of pregnancy.

A workshop organized by the National Heart, Lung, and Blood Institute and the Office of Rare Diseases Research in 1997 added an additional criterion proposed by Hibbard et al.[2] of left ventricular (LV) systolic dysfunction demonstrated by echocardiography with LV ejection fraction (LVEF) 45%, fractional shortening 30%, or both.

As there is paucity in literature to emphasize, the role of transesophageal echocardiography (TEE) being a mandatory diagnostic tool in such cases under regional anesthesia, we report a case of PPC in which TEE was used judiciously to optimize the fetal and maternal outcome.

Case Report

A 22-year-old woman, presented as gravida 1, para 0, at 37 weeks of gestation, with pregnancy induced hypertension and symptoms of cardiac failure. At 36th week of pregnancy, the patient had developed shortness of breath on mild exertion, chest pain and cough with mucoid sputum and pedal edema. At the time of admission, her heart rate was 112/min and blood pressure was 160/100 mmHg in right upper limb supine position. On auscultation of chest, there were bilateral coarse crackles along with a systolic murmur heard over mitral area. Her hemoglobin was 8.9 g/dl, with a normal blood profile. A transthoracic echocardiography revealed generalized hypokinesia, increased LV dimensions, moderate mitral regurgitation and mild tricuspid regurgitation, with an ejection fraction (EF) of 35%. A cardiologist opinion was sought, which led to the diagnosis of peripartum dilated cardiomyopathy. Treatment was started with intravenous (IV) furosemide 20 mg, tablet digoxin 0.25 mg and potassium supplement. Tablet methyl dopa and tablet labetalol were given with sips of water as antihypertensives. Once the symptoms of congestive cardiac failure resolved, cesarean section under epidural block was planned.

On preanesthetic assessment, she was quite comfortable at rest. On examination, pulse was 88 beats/min, blood pressure was 140/84 mmHg. There were fine crackles audible at both bases on auscultation of chest. The airway examination revealed a mallampatti Class III airway with normal neck movement. She was placed in ASA category III and taken up for elective lower section cesarean section with informed high risk consent.

An elective lower section cesarean section was performed under bolus epidural anesthesia with an epidural catheter in situ. She had delivered a 1.8 kg male baby. Later patient became hypotensive (pulse rate 146/min and blood pressure about 80/46 mmHg), which was managed with colloidal infusions and sympathomimetics in the form of dobutamine infusion (5 μg/kg/min). A TEE probe was inserted after delivery under sedation with midazolam (0.05-0.15 mg/kg IV) and fentanyl (2 mcg/kg IV). TEE revealed severe mitral regurgitation with a jet reaching the upper part of interatrial septum, central in nature with a vena-contracta width of 0.74 mm and effective regurgitant orifice area ≥0.4 cm2. The left ventricle was dilated with an EF of 20-25%, with all signs of cardiac decompensation during delivery as shown in Figures 1 and 2. However, the mean arterial pressure was 90-100/58-70 mmHg and heart rate was between 80 and 90 beats/min, which was maintained with colloids and dobutamine. Her postnatal course was uneventful and she was discharged from hospital on the 10th postnatal day.

Figure 1

Transoesophageal echocardiography image showing dilated left ventricle (two-dimensions mid-esophageal 4 chamber view)

Figure 2

Transoesophageal echocardiography image showing severe mitral regurgitation (two-dimensions color Doppler)

Discussion

Patients with PPC presents with the typical signs and symptoms of LV failure. When the disease develops during the last months of pregnancy the diagnosis of cardiac failure is made by signs and symptoms such as, fatigue, orthopnea, and pedal edema. Chest X-ray and echocardiography are very helpful for establishing the diagnosis of cardiac failure. The cardiovascular stress of labor and delivery may lead to cardiac decompensation. An impairment of myocardial contractility causes weakened systolic contraction, which leads, ultimately, to a reduction in stroke volume and cardiac output, inadequate ventricular emptying and cardiac dilation. Any factor causing tachycardia will decrease the systolic emptying time, leading to further decrease in stroke volume and cardiac output and hence reduction in systolic blood pressure. Vasodilator agent such as nitro-glycerine or nitroprusside for preload and after load reduction and dopamine, dobutamine and milrinone for inotropic support may be used. In our case we have used dobutamine as it takes care of rapid fall in systemic vascular resistance (SVR) in the short-term treatment of patients with cardiac decompensation due to depressed contractility, which could be the result of organic heart disease. Because the spontaneous deterioration of LV function has been reported in patients after either complete recovery or partial (LVEF 45%) recovery to 60 months after diagnosis, an annual echocardiographic examination is advisable in all patients with histories of post partum cardiomyopathy [PPCM].[3]

Preoperative echocardiography is indicated to assess the degree of biventricular impairment and valvular dysfunction. The role of midazolam and fentanyl for conscious sedation allows the patient to tolerate an unpleasant procedure like TEE, while maintaining cardiorespiratory function. Echocardiography is also useful for diagnosing mural thrombus, mitral or tricuspid regurgitation, and pericardial effusion.

Intraoperative TEE may also be useful for examining dynamic changes in cardiac performance and response to inotropes and fluid loading.

The use of TEE during surgery is an ideal continuous monitor of the adequacy of LV filling.

The use of TEE probe in these patients helps in delineating the biventricular function, systolic and diastolic status of the heart, the amount of fluid to be administered peri and postoperatively, any ischemia developing in the form of new regional wall motion abnormality and worsening of mitral regurgitation during surgery and thus aids us in choosing the type of anesthesia. Our patient developed severe mitral regurgitation, as a stress induced change, which showed as a dilated mitral annulus (3.9 cm) and prolapsing anterior mitral leaflet with LV dilatation. This was not so severe on 2nd day post-delivery and was well-managed with dobutamine and nitro-glycerin.

Regional anesthesia is preferred because of decreased cardiac sympathetic response.

Some authors have argued the case for general anesthesia in severe cases, as “cardiac reserve” is considered, so limited that any reduction in SVR due to epidural blockade could be catastrophic.[4] Others have argued the case for regional anesthesia on the basis that reduction in after load may be beneficial in a situation of poor ventricular function, where no outflow tract obstruction present.[5]

Considering the risk of aspiration, probable difficult intubation, the potential for acute cardiac decompensation and the inability to tolerate a lengthy caesarean delivery, an awake fiberoptic intubation to secure the patients airway and placement of lumbar epidural catheter for perioperative pain control can be justified.[6]

Conclusion

In this case we report a case of PPC management in which use of slowly titrated epidural anesthesia avoided the use of cardiodepresant drugs and improved myocardial performance by reducing LV afterload with an aid of TEE.

In patients suffering from PPC, with risk of precipitate labor, epidural anesthesia is an acceptable anesthetic alternative with TEE as a mandatory tool during conduct of anesthesia for optimal outcomes.

This report illustrates that an early initiation of medical treatment, careful administration of fluid under the guidance of invasive monitoring and noninvasive monitoring, importance of TEE and a well-tailored lumbar epidural technique satisfied provides the best possible outcome for both mother and infant.