Partial anomalous pulmonary venous return after orthotopic heart transplantation case report

Background Partial anomalous pulmonary venous return (PAPVR) is a congenital heart defect. Reports of repair and treatment in pediatric cases have been published, but incidence of PAPVR in adults is not common. To our knowledge, there has not been a diagnosis of left-sided PAPVR after a heart transplant an in adult patient. Case presentation A 62-year-old patient with ischemic cardiomyopathy and systolic heart failure underwent orthotopic heart transplantation. The immediate post-operative course was remarkable for an elevated cardiac index and pulmonary artery pressures as well as decreased systemic vascular resistance. The post-operative echocardiogram did not reveal an intra-cardiac shunt. However, computed tomographic angiography (CTA) showed a left superior pulmonary vein draining into the innominate vein. Operative repair of the left superior pulmonary venous connection to the left atrial appendage was completed under cardiopulmonary bypass with beating heart. Her hemodynamics improved immediately, and she had an unremarkable postoperative course. Conclusions While uncommon, any patient with a high cardiac output and abnormal hemodynamics after heart transplant should be evaluated for the existence of a shunt. While not a part of all traditional preoperative imaging protocols, a chest CTA should be considered if PAPVR is suspected as it can both diagnose the condition and enable a plot of the corrective course of surgical action.


Background
Partial anomalous pulmonary venous return (PAPVR) is a congenital abnormality where a single, or some, pulmonary veins fail to establish connection to the left atrium. As a result, one or more pulmonary veins drain anomalously to the right heart through the right atrium (intracardiac) or a systemic vein (extracardiac) [1]. Most commonly, the right-side pulmonary veins are involved in this abnormal connection in children, with the coexistence of an atrial septal defect [2]. Left-sided PAPVR is rarer and accounts for 10% of all reported PAPVR cases [3]. Adults with undiagnosed PAPVR may have an intact atrial septum and no pulmonary vein obstruction, resulting in minimal symptoms until an additional insult occurs to the heart. Because it is uncommon, the diagnosis of PAPVR may be overlooked. Herein, we report a unique case of adult, left-sided PAPVR that was identified after an orthotopic heart transplant (OHT).

Case presentation
A 62-year-old female underwent a diagnostic left heart catheterization in 2012. The procedure was complicated by a left main coronary artery dissection requiring an Open Access Since the patients' ejection fraction after CABG never improved, she transferred to our advanced heart failure clinic. Over two years, multiple right heart catheterizations (RHCs) were completed; Fick method calculations consistently demonstrated a normal cardiac index. However, the patient experienced worsening symptoms. Once she was profoundly symptomatic, her case was presented at the medical review board, and she was approved for an OHT. Her transplant was uneventful; however, during surgery an abnormal amount of blood was noted draining from the pulmonary veins. Her initial 24-h postoperative course was remarkable for a high cardiac index and right ventricular (RV) cardiac output, a low systemic vascular resistance, and an elevated pulmonary pressure (Table 1). While a shunt was suspected, an iatrogenic shunt was ruled out via bubble echocardiography. However, computed tomography (CT) scans revealed an abnormal left superior pulmonary vein draining into the innominate vein (Fig. 1). The CTA demonstrated the presence of an extracardiac shunt in the form of PAPVR.
After a multidisciplinary decision to pursue operative repair, the chest was re-opened. The left superior pulmonary vein (LSPV) was identified and visualized. A careful dissection was initiated from the pulmonary hilum toward the innominate vein outside the pericardium (Fig. 2). The venous connection was completely mobilized, a tributary branch was ligated, and the vein was transected at the innominate level. After mobilizing the vein, an end-to-side anastomosis was made between the LSPV and the donor heart left atrial appendage while under cardiopulmonary bypass with beating heart (Fig. 3). The heart and lung machine was used to avoid hemodynamic instability during the exposure of the left atrial appendage for the anastomosis. After the anastomosis and hemostasis, the patient was weaned from cardiopulmonary bypass and no inotropic support was required. The cannulas were removed after protamine was administered. The chest was closed in standard fashion, and the patient recovered in the intensive care unit. The patient was discharged home on Day 15.

Discussion and conclusions
Imaging studies contend that PAPVR exists in about 0.1-0.2% in the general adult population [4]. However, an autopsy series found that PAPVR is found in 0.4% of cases [5]. In contrast to symptomatic pediatric cases, adults with undiagnosed PAPVR have a silent clinical course or mild symptoms. Typically, these patients have intact atrial septum and no pulmonary vein obstruction. If found, surgical repair is possible. Majdalany and colleagues reported the identification of PAPVR in 43 adult patients; of those, 28 elected for operative repair in the setting of isolated pulmonary venous connection [2]. Surgical morbidity and mortality were low in their series and most improved the right ventricle size and pulmonary pressures [2]. The systemic venous connection found in adult PAPVR patients is a left-to-right shunt that can lead to high RV cardiac output and heart failure. These patients are at risk for developing pulmonary arterial hypertension due to chronic volume overload. Further, if an additional insult occurs to the heart, symptoms and complications from PAPVR result.
In the presented case, the patient initially tolerated the amount of left-to-right shunt throughout her adulthood. Symptoms of PAPVR began after the coronary dissection and continued to worsen for which she underwent OHT. Based upon the hemodynamics, a shunt was expected; however, echocardiography imaging was negative for intracardial shunt. Importantly, the use of CTA confirmed the PAPVR diagnosis. The documentation of a LSPV draining into the innominate vein was crucial; thus, CTA is the gold-standard imaging tool to diagnose PAPVR.
This clinical entity is not common, and few guidelines for newly diagnosed congenital heart disease in adults older than 40 years old have been published [6]. Surgical repair was relatively straightforward and re-established