Challenges with Managing Delayed Presentation of Persistent Truncus Arteriosus with Torrential Pulmonary Blood Flow in a Resource-Limited Setting.

Embryologically, incomplete conotruncal septation with resultant single aortopulmonary trunk and defective ventricular septation defines the congenital cardiac lesion known as persistent truncus arteriosus (PTA). Torrential pulmonary blood flow is inevitable when this rare lesion is further compounded by patency of the arterial ductus. Such was the case of a patient who presented with fast breathing, reduced suck, darkening of the tongue, and extremities. Urgent echocardiographic diagnosis was PTA (Type A1) with patent ductus arteriosus and pulmonary hypertension and left ventricular systolic dysfunction.

INTRODUCTION

Persistent truncus arteriosus (PTA) is rare, occurring in 1.2% of all congenital heart lesions.[1] Embryologically, cardiac neural crest mesenchymal cells differentiate to create the conotruncal ridges.[2] In PTA, there is abnormal migration of the conotruncal ridges, and the bulbar ridges fail to form, resulting in failed partitioning of the distal end of the bulbus cordis and truncus arteriosus.[3] A combination of anomalies including the absence of truncal spiraling, ventricular looping, and nonformation of the aorticopulmonary septum culminates in nondivision of the ventricular outflow tract.[3] A common large arterial trunk overriding a large, malaligned perimembranous ventricular septal defect results, and this is characteristic of PTA.[4]

In this condition, the systemic circulation, pulmonary circulation, and coronary circulation receive a mixture of oxygenated and deoxygenated blood; hence, in these children, cyanosis may be seen in early postnatal life.[3] They may lapse into congestive cardiac failure within few weeks of life and commonly present with complaints of dyspnea with feeding and failure to thrive. Clinical presentation may, however, vary with the extent of pulmonary blood flow (PBF) based on the Van Praagh and Van Praagh Classification,[5] where PBF could be increased (Type A1), nearly normal (Type A2 and A3), or decreased (Type A4). Although other cardiovascular anomalies such a patent ductus arteriosus (PDA) may be associated with PTA, to the best of the authors' knowledge, this has been hitherto reported only in Type A4 which is also associated with an interrupted aortic arch.

We report a case of an infant with a variant of PTA known to have increased PBF, further worsened by an associated PDA, severe pulmonary hypertension, and left ventricular systolic dysfunction who presented late in heart failure. The management challenges following delayed presentation and suggestions for a better outcome are herein highlighted.

CASE REPORT

An 8-week-old female infant was referred to the Emergency Paediatric Unit of the Limi Children's Hospital, Abuja, from a peripheral hospital. Her complaints were those of recurrent fast breathing, darkened mucous membrane of the oral cavity and lips, and digits noticed since the 1st week of life. The child also had feeding difficulties. She was a product of term gestation. The patient was repeatedly treated on outpatient basis at a peripheral hospital where she received oral medications including amoxicillin and Vitamin C. Chest radiograph showed enlarged cardiac shadow with increased pulmonary vascular markings, and an echo report from a peripheral hospital reported Tetralogy of Fallot (TOF). Pertinent examination findings at presentation include marked respiratory distress with mild cyanosis but no fever. She was tachypnoeic with a respiratory rate of 65 cycles/min, and SPO2 was 82% in room air and 96% when initially placed on intranasal oxygen. She had tachycardia with a pulse rate of 164 beats/min, brachiofemoral pulses were synchronous and femoral pulses were bounding, blood pressure was 76/38 mmHg (right arm in the supine position), and apex beat was displaced to the left fifth intercostal space and lateral to the midclavicular line, and she had a normal first heart sound, a loud and single second heart sound, and a grade three continuous murmur at the left sternal margin. Abdominal examination revealed a tender hepatomegaly of 5 cm below the right coastal margin. Echocardiography was repeated in our facility using GE echo machine with a 6 MHz probe, and she had PTA with an incompetent truncal valve and dilated branch pulmonary arteries (right = 10 mm and left = 8 mm) [Figure 1], a malaligned unrestrictive perimembranous ventricular septal defect measuring 16 mm [Figure 2], PDA with nonrestrictive left to right flow on continuous-wave Doppler [Figure 3], and pulmonary hypertension (TRV = 4.3 m/s, mPAP = 53.2 mmHg) [Figure 4]. M-mode showed reduced ejection fraction of 50% (Teich) and fractional shortening of 24%, although tricuspid annular plane systolic excursion was normal for age, 1.2 cm. She was managed on diuretics and vasopressors and maintained on intranasal oxygen at a low flow rate of 1 L/min. Parents were counseled on the child's condition and the ultimate need for surgery. However, her condition deteriorated and she died within the first 2 days of hospitalization.

Figure 1

Parasternal short-axis view showing a single truncal vessel with confluent pulmonary arteries branching posteriorly

Figure 2

Parasternal long-axis view showing malaligned ventricular septal defect with an overriding single truncal vessel

Figure 3

Patent ductus arteriosus with nonrestrictive left to right flow on continuous-wave Doppler

Figure 4

Elevated peak tricuspid regurgitant velocity on continuous-wave Doppler

DISCUSSION

Our patient who had a main pulmonary artery arising from the truncus arteriosus (overlying a malpositioned ventricular septal defect) and bifurcating into the branch pulmonary arteries fits the Type A1 Van Praagh and Van Praagh Classification.[5] A PDA is usually present in Type A4 PTA to allow for lower-extremity blood flow, as this PTA variant is associated with an interruption of the aortic arch distal to the takeoff of the left carotid artery.[6] The incidental association of PDA with a Type A1 PTA in our patient clearly compounded the background increased PBF, understandably accounting for the heart failure at presentation. The child immediately received frusemide, a loop diuretic to reduce preload, and then dopamine to enhance myocardial contractility. Although the child was desaturated at presentation, we were cautious with the use of oxygen because it is a pulmonary vasodilator which could worsen pulmonary overcirculation and pulmonary congestion and in turn exacerbate respiratory distress. From the surgical perspective, banding of the main or branches of the pulmonary arteries and possibly ligation of the PDA could temporarily control congestive heart failure in our patient, as she was unfit for definitive repair.[7] Supporting this palliative measure, Ruan et al.[8] reported an initial pulmonary artery banding and subsequent repair at the age of 33 years in a Chinese male with Type 1 PTA. Whereas their definitive repair may be seen as overly delayed, the banding was a needful interim measure. This is obviously desirable in a complicated picture like that of our patient. Most worrisome, however, is the fact that in our immediate environment with resource constraints, no form of surgical intervention is readily available. Although Nwafor et al.[9] reported a successful repair of Type 1 PTA in Enugu, Nigeria, their 15-month-old patient differed from ours in not being in heart failure as PBF was less torrential. Our patient also had severe truncal valve incompetence, pulmonary hypertension, and left ventricular systolic dysfunction, all portending a worse prognosis.[10] The Enugu team performed the corrective surgery with the aid of a foreign medical mission, the Global Cardiac Alliance, Memphis, USA. Just like theirs, our patient had been previously misdiagnosed and this further reflects a lack of adequately trained manpower in pediatric cardiac imaging. TOF with pulmonary atresia (initially supposed by echo done prior to presentation) differs from PTA on echo as in the later, a large single artery (truncus arteriosus) arises from the heart. This single truncal vessel clearly branches posteriorly giving off the pulmonary vessel. In the former, however, echo studies reveal absence of a direct connection between the right ventricle and the pulmonary artery; the small branch pulmonary arteries existing with a vertical ductus can be imaged from high parasternal or suprasternal transducer position. Obviously, the difference between the two cardiac anomalies will be challenging when echo is performed by an untrained staff for congenital heart disease.

This is not the case in the developed world where presentation is early, diagnosis is accurate, and surgical repair is early in neonatal life.

CONCLUSION

PTA has a poor outcome in those presenting late and when surgical correction, at least a palliative pulmonary artery banding, is not readily available. An in utero diagnosis using fetal echocardiography and transfer for delivery in a facility capable of surgical repair will reduce infant mortality in our environment due to congenital heart disease such as present in this report.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.