EXPLANATION


Cor triatriatum (“triatrial heart”), a rare cardiac anomaly found in approximately 1 in 1000 patients with congenital heart disease, describes the anatomical finding of a membrane dividing the left atrium (sinister) or right atrium (dexter) into two chambers. Cor triatriatum sinister results from an inadequate merging of the common pulmonary vein with the left atrium during heart development. In this malformation, a fibromuscular membrane with one or more orifices separates the atrium into an upper chamber, with the pulmonary veins, and a lower chamber with the left atrial appendage and the mitral valve. The degree of obstruction to blood flow through the orifices in the membrane determines the severity of the patient’s symptoms. Significant obstruction may result in severe left atrial hypertension, low cardiac output, and pulmonary venous hypertension. The symptoms and pathophysiology are similar to severe mitral stenosis. Most patients develop symptoms during the first year of life, or earlier if severe obstruction is present. There are also reports of completely asymptomatic adult patients with multiperforated membranes. Cor triatriatum sinister is usually associated with other congenital cardiac malformations including hypoplastic left heart syndrome, left superior vena cava, and anomalous pulmonary venous drainage.


Anesthetic considerations and goals are similar to mitral stenosis, which include the following: 1) preservation of contractility and normal sinus rhythm; 2) low to low-normal heart rate to enhance left ventricular filling time in the presence of inflow obstruction; 3) maintenance of adequate preload (central venous pressure[CVP]) to minimize the functional obstruction to left ventricular (LV) filling; and 4) adequate afterload for maintenance of systemic and coronary artery perfusion. Maneuvers to decrease pulmonary vascular resistance (PVR) before relieving pulmonary venous obstruction can result in the worsening of pulmonary venous hypertension. Conversely, after repair, pulmonary arterial hypertension may indicate a need for inhaled nitric oxide during the postoperative period.


In this case scenario, during the pre-bypass period, the hemodynamic goals are normal sinus rhythm, low to low-normal heart rate, maintenance of adequate preload (CVP) and afterload (mean arterial pressure (MAP)), and avoidance of low PVR. Decreased afterload can result in coronary artery hypoperfusion in the setting of a reduced MAP pressure in a patient with impaired left ventricular filling/stroke volume. Excessive preload or high central venous pressure (CVP) can exacerbate left atrial hypertension and pulmonary edema, whereas low preload and CVP can further reduce stroke volume (LV end-diastolic volume) and cardiac output. Left atrial hypertension and pulmonary venous hypertension with secondary pulmonary arterial hypertension may require initiation of inhaled nitrous oxide post-operatively.


REFERENCES


Spaeth J, Loepke A. Anesthesia for left-sided obstructive lesions. In: Andropoulos DB, Mossad EB, Gottlieb EA, eds. Anesthesia for Congenital Heart Disease. 4th ed. Hoboken, NJ; Wiley-Blackwell. 2023: 513-514.


Stout KK, Daniels CJ, Aboulhosn JA, et al. 2018 AHA/ACC Guideline for the Management of Adults With Congenital Heart Disease: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines [published correction appears in J Am Coll Cardiol. 2019 May 14;73(18):2361]. J Am Coll Cardiol. 2019;73(12):1494-1563. doi:10.1016/j.jacc.2018.08.1028