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Cor triatriatum
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Pathophysiology
A rare congenital cardiac anomaly, cor triatriatum occurs when there is failure of the normal development of the heart where the pulmonary veins enter the left atrium. A fibromuscular membrane divides the left atrium into two parts. The pulmonary venous return enters the left atrium proximal to the membrane. The mitral valve and left atrial appendage occur distal or downstream to the membrane. A communication allows pulmonary venous return to enter the proximal left atrium and pass through the mitral valve to the left ventricle. In some variations, a patent foramen ovale or atrial septal defect occurs between the proximal left atrium (receiving pulmonary venous return) and the right atrium, usually with an additional communication between the right atrium and the distal chamber.
Presentation of the patient with cor triatriatum is variable. When pulmonary venous return to the mitral valve is severely obstructed, patients present with pulmonary artery hypertension, congestive heart failure, and depressed cardiac output. By contrast, patients with lesser degrees of obstruction may present later in life or go undiagnosed for decades. Early severe obstruction predicts poorer prognosis. In patients with an atrial septal defect that communicates with the proximal chamber, left- to-right shunting occurs. Presentation can occur later, and signs and symptoms are that of pulmonary overcirculation and left-to-right shunting.
Surgical technique
Repair is performed soon after diagnosis. Repair is carried out via median sternotomy using cardiopulmonary bypass and aortic cross-clamping. The obstructive membrane is resected via right atriotomy, working through an atrial septal defect, or via left atriotomy. Any associated defects are repaired at this time. Transesophageal echocardiography is performed to help assess the adequacy of repair. Aortic cross-clamp time usually is short.Postoperative Considerations
The postoperative course following elective repair of cor triatriatum without obstruction to pulmonary venous return is usually benign. By contrast, the postoperative course following repair with obstruction to pulmonary venous return is more complex; episodes of elevated pulmonary artery pressure in the postoperative period can result in cardiovascular instability.
Invasive monitors used include arterial and central venous catheters. An LA line is used when needed for hemodynamic management. LA pressure acts as a surrogate for left ventricular end diastolic pressure, an excellent indicator of left ventricular performance. Non-invasive monitors include NIRS (near infrared spectroscopy) probes to assess adequacy of regional and global perfusion and traditional pulse oximetry. Vasoactive agents might include epinephrine and/ or milrinone. Numerous other agents are available and are tailored to the specific needs of the patient, targeting adequate oxygen delivery to the tissues of the body and optimization of cardiac output.
Excessive postoperative bleeding is an uncommon complication. Cardiac rhythm disturbances can occur following surgery. Atrioventricular conduction disturbances, atrial tachydysrhythmias, and sinus bradycardia are sometimes encountered. Pulmonary artery hypertension encountered postoperatively may require a period of sedation and mechanical ventilation. Inhaled nitric oxide should be available if needed. Pulmonary vascular resistance and pressure usually decrease gradually following repair, and extubation is often possible within days to one week after surgery. Length of hospital stay following repair averages 10 days to 3 weeks.