Abstract
Keywords
Introduction
Persistent truncus arteriosus is a rare congenital heart defect that affects approximately 2% to 4% of all cases. It arises from the failure of the truncus arteriosus to divide in utero, leading to a single origin for the pulmonary, aortic, and coronary arteries. 1 The condition can be fatal without correction in early infancy, and even with surgical intervention. It can be complicated or even contraindicated in cases of late presentation due to elevated pulmonary vascular resistance. As a result, survival into childhood and adulthood is rare. 2 In this report, we aim to provide insights into effective surgical management of late-presenting patients with truncus arteriosus who might not have been considered for interventions at earlier ages.
Patients and Methods
We performed a retrospective study examining outcomes of patients who were repaired for this anomaly at our institution more than three years old. In-hospital and outpatient follow-up data were analyzed. All patients underwent preoperative echocardiography, computed tomography (CT), and cardiac catheterization. This study received institutional review board approval.
Results
We identified seven patients who underwent late repair of truncus arteriosus. These patients exhibited a wide age range, spanning from 3 years and 2 months to 11 years and 6 months. There were six females and one male in the cohort, with a median weight of 16 kg with weights varying between 8.8 kg and 25 kg. Detailed patient data are outlined in Table 1.
Preoperative Clinical, Echocardiographic, and Hemodynamic Catheterization Data.
Abbreviations: LPA, left pulmonary artery; PAPVD, partial anomalous pulmonary venous drainage; RPA, right pulmonary artery; WU/M2, Wood Units per square.
Clinical Characteristics and Preoperative Evaluation
Prior to surgery, a comprehensive evaluation utilizing echocardiography and cardiac CT revealed features of truncus arteriosus and associated anomalies. Among them, four cases were categorized as truncus arteriosus type I, two cases as type II, and one patient as type III according to the Collett & Edwards classification. 3 Truncal valve morphology varied, with some cases displaying a trileaflet configuration and others a bicuspid morphology. Additionally, several associated anomalies were detected, including partial anomalous pulmonary venous drainage (PAPVD) in two cases, interrupted aortic arch in one case, and proximal pulmonary branch stenosis in another case.
Preoperative hemodynamic catheterization showed that pulmonary vascular resistance index (PVRI) was reversible ranging from 0.7 to 8.6 Wood Units per square meter (WU/M2) before 100% oxygen administration and subsequently decreasing to a range of 0.7 to 4.4 WU/M2 after 100% oxygen administration (as shown in Table 1). Notably, five patients, with a median age of 11.5 years and an age range of 1 to 29 years, were excluded from the study due to their post-oxygen administration PVRI exceeding 6 WU/M2. Consequently, they were not considered eligible for surgery and were thus excluded from further analysis in this study.
Surgical Procedure
The surgical correction was conducted using a standard median sternotomy approach with distal aortic and bicaval cannulation. The right and left pulmonary artery branches were mobilized up to the prebranching level and looped before initiating cardiopulmonary bypass (CPB). Cardiopulmonary bypass was established at systemic moderate hypothermia. Aortic cross clamp (ACC) was applied. Complete asystole was achieved using anterograde cold cardioplegia in the truncal root. The pulmonary arteries were exposed through a transverse anterior truncal incision to safely remove the pulmonary artery bifurcation. To access the ventricular septal defect (VSD), a right ventriculotomy was performed through the right ventricular infundibulum.
The VSD was closed using a Gore-tex patch. In all cases, valved conduits either aortic homograft or freestyle bioprosthesis were employed to establish continuity between the right ventricle and the pulmonary artery. In five patients, a small atrial septal defect (ASD) was left open. Patients with more than mild truncal valve regurgitation underwent valve repair, as described in a previous report published by our group. 4 In patients with a quadricuspid valve and thin preserved four leaflets, tricuspidization is performed. This technique entails excision of the noncoronary sinus, leaflet, annulus, and importantly remodeling the subvalvular region to ensure smooth flow of blood from the left ventricle to the neoroot. In patients with a tricuspid or bicuspid truncal valve, techniques similar to those developed and used for bicuspid aortic valve are used. This should be combined with reduction of the enlarged sinuses and creation of a sinotubular junction to match the distal end of the ascending aorta.
In a single case where both pulmonary arteries exhibited origin stenosis, reconstruction of the stenotic segments was undertaken. In another patient who underwent repair for an interrupted aortic arch, the arch repair was performed with selective antegrade cerebral perfusion at a temperature of 20 °C. In patients with PAPVD, anomalous pulmonary veins were redirected to the left atrium through ASD secundum.
Pulmonary artery pressure, assessed post-CPB, remained below two-thirds of systemic pressure for all patients except one, where it was near systemic pressure.
The mean ACC and CPB times were 201.6 + 29.07 and 331 + 49.82 min, respectively. Intraoperative transesophageal echocardiography was used in all patients and revealed satisfactory repair in all without any unintended residual septal defects.
Postoperative Course
To facilitate the weaning off CPB, inotropic agents were initiated prior to the process, consisting of a minimum dose of 0.05 µg/kg/min of noradrenaline combined with 0.5 mg/kg/min of milrinone. Additional doses were administered as necessary.
Patients number 1 and 7 encountered episodes of pulmonary hypertensive crises, manifested clinically by low cardiac output in patient 1 and acute desaturation in patient 7. These episodes were managed by appropriate analgosedation, hyperventilation, and careful management of acidosis and other potential triggers such as arrhythmia, suction, and hypoxia. Unfortunately, inhaled nitric oxide was not accessible, so alternative pulmonary vasodilators such as sildenafil and bosentan were utilized.
Except for a single patient who had truncus arteriosus with interrupted aortic arch and was extubated after four days, all the other patients were successfully extubated within 72 h. This particular patient required noninvasive pressure support due to chest infection and diaphragmatic palsy. Additionally, the patient was dependent on noninvasive positive pressure ventilation, necessitating diaphragmatic plication The median duration of stay in the intensive care unit (ICU) was nine days and with a range from 3 to 18 days, while the median hospital stay was 29 days with a range from 21 to 60 days.
Patients experiencing pulmonary hypertensive crises or those exhibiting right ventricular pressure exceeding half of the systemic pressure were discharged while on oral pulmonary vasodilators, specifically sildenafil along with heart failure medications such as diuretics and angiotensin-converting enzyme inhibitors. Their progress is regularly monitored during follow-up to evaluate the possibility of discontinuation or modification of medication dosages.
A six-month follow-up in five patients revealed a notable absence of major complaints or symptoms among the patients. Echocardiographic (Table 2) and CT (Figure 1) images revealed the results of aortic valve regurgitation ranging from mild to mild/moderate in severity. The conduit valve demonstrated trivial regurgitation, and right ventricular systolic function was deemed good in all cases, with only one instance showing mild impairment. However, one patient displayed a residual VSD measuring 5 mm across the patch, which resulted in a left-to-right shunt. Cardiac MRI further revealed a QP:QS ratio of 1.6 in this particular case, and the patient is being assessed for percutaneous closure.
(a and b) Computed tomography (CT) images before repair. (c and d) After repair in patient number 2.
Follow-Up Clinical, Echocardiographic, and CT Data After Six Months.
Abbreviation: CT, computed tomography; RV, right ventricle.
Patients numbered 3 and 5 had no follow-up assessments, as the period following their surgical procedures was less than six months.
Discussion
Truncus arteriosus is a rare congenital heart defect that presents a significant challenge in the management of affected patients. In the current era, primary repair is considered the treatment of choice for truncus arteriosus during the neonatal period. This involves creating a connection between the right ventricle and pulmonary artery and closing any VSDs to separate the pulmonary and systemic pathways. 5 If left untreated, the condition can lead to elevated pulmonary vascular resistance, rendering surgical repair of truncus arteriosus more difficult or even contraindicated. 6
Assessing the operability of these patients posed challenges. The widely acknowledged threshold for operability in children with significant left-to-right shunts was a PVRI ranging from 6 to 8 WU/M2. In our series, preintervention hemodynamic catheterization was performed in all patients, which showed that pulmonary vascular resistance was reversible allowing for successful repair in all cases.
In 1967, McGoon, Rastelli, and Ongley achieved the first successful surgical repair of truncus arteriosus. Their approach involved utilizing an aortic homograft to establish a connection between the right ventricle and the pulmonary artery. Since then, several reconstruction methods have been developed, leading to ongoing debates regarding the optimal technique and the ideal age for performing surgery. 7 Our group introduced a new approach that involves using autologous arterial trunk tissue to directly connect the right ventricle to the pulmonary artery, resulting in good clinical and imaging outcomes. 4 However, in the current series, we employed valved conduits to avoid free pulmonary regurgitation with anticipated high pressure in the right ventricle.
The decision to leave a shunt, such as a small ASD in those patients with expected pulmonary hypertension crises after repair can provide a pathway for right-to-left shunting, thereby maintaining cardiac output. This can potentially decrease the likelihood of postoperative pulmonary hypertensive crises and improve outcomes. However, there are also potential risks associated with leaving a shunt. These include the risk of mild cyanosis and paradoxical embolism, as well as the risk of long-term right ventricular overloading (in cases of left to right shunt). Therefore, the decision to leave a shunt in place should be carefully weighed on a case-by-case basis.
Pulmonary hypertensive crises were prevented and managed by deep sedation and analgesia, avoiding acidosis, support of the right ventricle by milrinone, and oral pulmonary vasodilators such as sildenafil and bosentan. Most of the patients did not need to continue these medications after discharge from the ICU.
Regarding postoperative outcomes, all patients had successful repair of truncus arteriosus and were safely discharged home.
Conclusion
For cases of delayed presentation and diagnosis of truncus arteriosus, surgical repair can remain a viable option. It is important to assess the individual patient's specific condition and determine the most appropriate management. Furthermore, findings from the post-oxygen challenge tests revealing a PVRI of less than 6 WU/M2 seem to correlate with a favorable outcome after repair.
Footnotes
Authors' Statement
Proper and informed consent has been obtained from the respective parents or guardian of the patients for the publication of this study.
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
