Author: Anila B. Elliott, MD - University of Michigan, C.S. Mott Children’s Hospital
A 3-day-old male with total anomalous pulmonary venous return (TAPVR) is transferred from an outside hospital. He is hemodynamically stable on no vasoactive medications and supported on nasal cannula at 2L/min with an FiO2 of 0.21. Transthoracic echocardiography shows unobstructed flow of pulmonary venous blood to systemic venous circulation with right to left shunting through a moderate-sized secundum atrial septal defect. Which of the following is a risk factor for increased morbidity and mortality?
EXPLANATION
Total anomalous pulmonary venous return (TAPVR) is a rare congenital cardiac lesion, occurring in 1-3% of the congenital heart disease population1. There are four main types of TAPVR: supracardiac (most common), cardiac, infracardiac and mixed. Mixed TAPVR is the least common and the most challenging to surgically repair as there is often no pulmonary confluence and multiple pulmonary venous connections both above and below the diaphragm2.
Since the introduction of prostaglandins to maintain ductal patency in many congenital cardiac lesions, obstructed TAPVR remains one of the few true congenital cardiac surgical emergencies.
TAPVR can be associated with other anomalies, including heterotaxy, hypoplasia of left-sided structures, or other lesions requiring palliation down the single-ventricle pathway2.
A pure right-to-left shunt across the atrial septum on echocardiogram is usually indicative of TAPVR1. A key factor in peri-operative management is whether there is obstruction to pulmonary venous flow. On echocardiography, flow acceleration in pulmonary veins of ≥ 2.0 m/sec indicates significant obstruction2. Clinical presentation of obstructed TAPVR includes severe pulmonary edema, pulmonary hypertension, cyanosis, metabolic acidosis and cardiogenic shock3. Management involves maintaining forward flow and avoiding pulmonary vasodilation, which can lead to increased flow in the already congested pulmonary circulation. In those with unobstructed pulmonary veins, as long as there is adequate mixing, they may present with mild cyanosis, signs of pulmonary over circulation, and potentially right-sided dilation/hypertrophy depending on age1.
Supracardiac TAPVR is usually unobstructed but may become obstructed if the vertical vein passes between the bronchus and the left pulmonary artery2. Infracardiac TAPVR usually presents as (or is considered to be) obstructed due to the long course of the vasculature to return to the atrium, with the potential for narrowing and obstruction at several points, especially in the intra-hepatic region3. Cardiac TAPVR is less likely to be obstructed1.
The most common post-operative complication includes recurrence of pulmonary venous obstruction and has been reported to occur in 8-54% of cases2. Other risk factors for increased morbidity and mortality include single ventricle multidistributive circulation, obstructed veins pre-operatively, pre-operative invasive ventilation, and pulmonary hypertension1,3.
The correct answer is choice C: perioperative complications (including mortality) are increased2,3 in patients with persistent pulmonary hypertension. Pulmonary veins draining into the coronary sinus describe cardiac TAPVR, which is less likely to be obstructed1 and a patient with a vertical vein and unobstructed flow is less likely to present in extremis with pulmonary hypertension or end-organ dysfunction3.
REFERENCES
1. Hancock Friesen, CL,, Zurakowski, D., Thiagarajan, RR., et al. Total anomalous pulmonary venous connection: an analysis of current management strategies in a single institution. Ann Thorac Surg. 2005; 79(2): 596-606
2. Karamlou, T., Gurofsky, R., Al Sukhni, E., et al. Factors associated with mortality and reoperation in 377 children with total anomalous pulmonary venous connection. Circulation. 2007; 115:1591-1598
3. Schulz, A., Wu, DM., Ishigami, S., et al. Outcomes of total anomalous pulmonary venous drainage repair in neonates and the impact of pulmonary hypertension on survival. JTCVS Open. 2022; 12: 335-343
