Introduction
Institutional resources and knowledge gaps are supplemented via collaboration. Heart University, [https://www.heartuniversity.org/] 1 , a free educational website consisting of webinars, training curricula, case discussions, etc., facilitates knowledge sharing in its webinar series “Cardiology Across Continents.” The sessions are presented by programs differing in resources and geography, comparing and contrasting management of difficult cases (Figure 1). For such cases, this unique discussion format enables interesting and important insights for patient management to improve outcomes. Reference Peck, Neal and Redington2,Reference Arunakumar, Shetty, Mahendran, Neal, Gowda and Peck3,Reference Warren, Greiner, Issacs, Neal, Peck and Sasikumar4 We present the 15th installment of the series, entitled “Complicated Post-op Course in an infant with Tetralogy of Fallot” for a case-based educational article.
Heart University’s case-based discussion series format for “Cardiology across continents”.
Case report
Presentation of patient in resource limited setting—Hospital Nacional de Pediatria J.P. Garrahan, Buenos Aires, Argentina
A term male was hypotonic, cyanotic, bradycardic, and without respiratory effort at birth, prompting cardiopulmonary resuscitation, intubation, and admission to the NICU for mild hypoxic-ischaemic encephalopathy. Subsequently, a systolic ejection murmur was noted, prompting transfer to a tertiary care centre for suspected CHD. The initial echocardiogram demonstrated Tetralogy of Fallot with a large subaortic ventricular septal defect, infundibular narrowing, a bicuspid mildly hypoplastic pulmonary valve (6.0 mm, PHN Z-score −2.2), with a peak gradient of 35 mmHg. After stabilisation from hypoxic ischaemic encephalopathy, weaning from continuous positive airway pressure to room air with oxygen saturations >89%, and no evidence of hypercyanotic spells, the patient tolerated feedings, was started on propranolol, then discharged home with planned surgical repair at 6 months of age. At home, no hypercyanotic spells occurred while on propranolol. Due to unclear anatomic characterisation of collateral presence by echocardiography, pre-op workup included a chest CT, elucidating four aortopulmonary collaterals from the descending thoracic aorta, and normal coronary artery anatomy (Figure 2).
Four AP collaterals, measuring 1.4 mm, arising from the descending thoracic aorta demonstrated on coronal view ( a ), and 3D renderings ( b , c ).
Surgical repair at 6 months of age included a non-valve-sparing transannular patch (pulmonary valve annulus at time of surgery was 6.6 mm with PHN Z score −3.2), ventricular septal defect patch with pericardium via right ventriculotomy, and patent foramen ovale closure via right atriotomy. Bypass time was 152 minutes, and aortic cross-clamp time was 117 minutes with no arrhythmias. The patient returned intubated with a closed chest. During the post-op course, progression was slow, requiring high ventilatory pressures (peak inspiratory pressures up to 30) and FiO2 60%. High cardiovascular support and diuretics were needed, including epinephrine, norepinephrine, vasopressin, milrinone, intravenous furosemide, and aminophylline. On post-op day 2, it was determined the required support was disproportionate to typical postoperative needs, furthering investigation. Echocardiographic data showed decreased right ventricular systolic function, likely from the ventriculotomy, as well as increased pulmonary blood flow seen via the pulmonary veins and a dilated left atrium. This, in the setting of vascular congestion on a chest X-ray, and low cardiac output prompted a catheterisation.
Proposed management plan of patient in non-resource-limited setting (Division of Pediatric Cardiology, Department of Pediatrics, University of Minnesota Masonic Children’s Hospital, Minneapolis, MN, USA)
Outpatient setting
The Minnesota team agrees that a patient with Tetralogy of Fallot, clinically sufficient pulmonary blood flow and no hypercyanotic spells can be discharged home with outpatient follow-up. In general, the team utilises a beta blocker in the setting of hypercyanotic spells with urgent surgical expedition. Preoperative imaging typically involves just an echocardiogram, utilising CT scans when anatomy by echocardiogram is insufficient, such as coronary artery anatomy. Assuming stability, the Minnesota team recommends elective repair of Tetralogy of Fallot at 6–8 weeks of life. Repairs at this time are shown to be safe and without increased intervention rates. Reference Cunningham, Donofrio, Peer, Zurakowski, Jonas and Sinha5 If elective repair is completed prior to 3 months, the need for non-elective repair decreases by 40–50% decreasing the morbidity associated with non-elective repair. Reference Peer, Zurakowski, Jonas and Sinha6
Surgical techniques
For the Minnesota team, pulmonary valve annulus size determines surgical technique. If the size is greater than −2.0 Pediatric Heart Network Z-score, a valve-sparing repair is appropriate. If its borderline small, −2.0 to −3.0 Pediatric Heart Network Z score, a valve-sparing repair is attempted, with checking the gradient and right ventricle response, to prevent a non-valve-sparing repair. Additionally, the surgical team always leaves an atrial communication as a pop-off for elevated right ventricular pressures and attempts extubation as soon as possible, reducing right ventricle afterload. The team also discussed optimal perfusion management and bypass flow in the setting of high aortopulmonary collateral burden.
Post-op ICU setting
The Minnesota team agrees the required cardiorespiratory support was disproportionate to the patient’s surgical repair. The amount of ventilatory support necessitated assessment for atelectasis, pleural effusions, diaphragm paralysis, and pulmonary haemorrhage. Regarding high haemodynamic support, a typical work-up would include assessing for ventricular systolic/diastolic function, sepsis, and pericardial effusion, while the increased diuretic need prompts echo assessment for residual shunts or valvular dysfunction.
One of the main concerns for this patient with failure to progress following Tetralogy repair is right ventricular diastolic dysfunction. A main discussion point was the importance of leaving an atrial communication ensuring preload to the left ventricle with right ventricular diastolic dysfunction. Without atrial communication, poor cardiac output was likely due to right ventricular diastolic dysfunction, which would be managed with milrinone, fluid balance, and heart rate control.
The aortopulmonary collaterals likely also contributed to the patient’s support needs. While non-invasive testing can evaluate alternative aetiologies, catheterisation can be both diagnostic and therapeutic for aortopulmonary collaterals. Studies demonstrate aortopulmonary collaterals should be included in the differential with difficulty weaning support. Doulamis et al. (2022) Reference Doulamis, Marathe and Oh7 described a series of patients following arterial switch operations for D-transposition of the great arteries who were only able to wean off post-op cardiorespiratory support once they were taken to the cath lab and had collaterals closed. While aortopulmonary collateral vessels are less common in patients with Tetralogy of Fallot, this should be considered when other more common aetiologies of prolonged ICU courses are ruled out.
Course of patient at Hospital Nacional de Pediatria J.P. Garrahan, Buenos Aires, Argentina
The diagnostic catheterisation was notable for a Qp:Qs of 2.2:1. With closure of the collaterals, the patient tolerated support weans and was eventually discharged home.
Discussion
Our discussion highlights pre-op medical management, surgical technique, and post-op ICU management. Per the Minnesota team, repair at 6–8 weeks mitigates non-elective repair sequelae, while leaving an atrial communication enables a pressure pop-off for the right heart and attempting a valve-sparing repair as appropriate. Collateral closure in the pre-op should be considered for future cases. In the post-op setting, the significance of right ventricular diastolic dysfunction in late repairs was highlighted, which may contribute to poor cardiac output, especially in the absence of an atrial communication.
Disproportionate postoperative cardiorespiratory support warranted further investigation with catheterisation. Unique to this case is the presence of aortopulmonary collaterals, which should be on the differential if patients do not progress in the post-op setting. The postoperative course was likely multifactorial involving collateral burden and right ventricular diastolic dysfunction.
Conclusion
Cardiology across continents is a vital resource for discussing management options for complex cases across institutions. This case highlighted insights into perioperative management, surgical techniques, and possible aetiologies of inability to wean support, with subsequent solutions in an atypical case of Tetralogy of Fallot with AP collaterals.
Financial support
None.
Competing interests
None.
Ethical standard
The authors assert that all procedures contributing to this work comply with the ethical standards of the relevant national guidelines on human experimentation and with the Helsinki Declaration of 1975, as revised in 2008.
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