A single center experience with minimally invasive approaches in congenital cardiac surgery

Background

Cardiac surgery is a technically demanding field with an appreciable learning curve that extends beyond formal training. Minimally invasive congenital cardiac surgery has one of the steepest learning curves. Early complications often discourage surgeons, particularly those at lower volume centers, from pursuing innovative approaches. Over the past three years, we have utilized a number of minimally invasive approaches including pulmonary valve replacement, anomalous aortic origin coronary artery repair, atrial septal defect repair, epicardial lead placement, and partial anomalous pulmonary venous return. Herein we report on our experience performing minimally invasive congenital cardiac surgery, lessons learned, and how our approach has evolved.

Methods

We performed a single institution, retrospective review, wherein continuous variables were reported as median (interquartile range).

Results

Between September 2017 and May 2020, minimally invasive approaches were attempted on 49 patients with a median age of 19 years (14–47 years) for nine distinct congenital cardiac diagnoses. Seven patients (14%) required conversion to larger incisions, including four patients or 36% of those undergoing anomalous aortic origin of a coronary artery repair. Patients who were converted had a higher body mass index 33.1 (31.7–37.8) than those who were not (24.2, 20.8–29.3) (P=0.009).

Conclusions

Minimally invasive approaches for congenital cardiac conditions require a team approach. Patients with a body mass index greater than 30 should be counseled on the higher rate of conversion. We no longer perform minimally invasive anomalous aortic origin of a coronary artery repair given the high rate of conversions and complications. Surgeons attempting this procedure should do so cautiously.

Flow Monitoring of ECMO Circuit for Detecting Oxygenator Obstructions

Oxygenator thrombosis during extracorporeal membrane oxygenation (ECMO), is a complication that necessitates component replacement. ECMO centers monitor clot burden by intermittent measurement of pressure drop across the oxygenator. An increase in pressure drop at a preset flow rate suggests an increase in resistance/clot formation within the oxygenator. This monitoring method comes with inherent disadvantages such as monitoring gaps, and increased risk of air embolism and infection. We explored utilizing flow measurement, which avoids such risks, as an indicator of ECMO circuit obstructions. The hypothesis that flow rate through a shunt tube in the circuit will increase as distal resistances in the circuit increases was tested. We experimentally simulated controlled levels of oxygenator obstructions using glass microspheres in an ex vivo veno-venous ECMO circuit and measured the change in shunt flow rate using over the tube ultra-sound flow probes. A mathematical model was also used to study the effect of distal resistances in the ECMO circuit on shunt flow. Results of both the mathematical model and the experiments showed a clear and measurable increase in shunt flow with increasing levels of oxygenator obstruction. Therefore, flow monitoring appears to be an effective non-contact and continuous method to monitor for obstruction during ECMO.

Complex Repair of a Completely Fused Nullicuspid Aortic Valve Late in Adolescence

We report a case of an 18-year-old female who presented with severe aortic stenosis and insufficiency, eight years following resection of a subaortic membrane. On echocardiography, she was found to have a completely fused or nullicuspid valve, with three equal sinuses and three commissural fusions. Aortic valve repair included leaflet tricuspidization, three commissurotomies, trileaflet ring annuloplasty, and pericardial leaflet reconstruction. At one year follow-up, the patient is asymptomatic, with stable gradients.

Anomalous Aortic Origin of a Coronary Artery Repair Through an Anterior Minithoracotomy

OBJECTIVE

The benefits of minimally invasive adult cardiac surgery are well established. Nevertheless, minimally invasive congenital cardiac procedures, even for adult patients, are uncommon. In 2018, we started repairing anomalous aortic origin of a coronary artery (AAOCA) through a 5 cm anterior minithoracotomy when possible to improve cosmesis and avoid sternal precautions. We hypothesized this approach was safe and reliable.

METHODS

A 5 cm incision was made in the right second intercostal space. The incision was carried down to the pericardium while preserving the internal mammary artery. With the pericardium in view, the second and third ribs were disarticulated. Central cardiopulmonary bypass was established, and the repair was carried out based on the patient's anatomy. The technique was modified to a left anterior minithoracotomy for 1 patient who required pulmonary artery translocation. At any point, if the dissection or repair was not progressing appropriately, the minimally invasive exposure was converted to a partial or traditional median sternotomy.

RESULTS

Between June 2018 and June 2019, 11 patients underwent minimally invasive anomalous coronary repair. Four patients (3 with body mass index >30) were converted to traditional sternotomy due to poor visualization. Postoperatively, 1 patient required coronary artery bypass after 335 days, due to extensive collaterals and stable angina. Otherwise, at a median follow-up of 437 days (IQR 340 to 480), patients had resumed baseline activity without recurrent symptoms.

CONCLUSIONS

Minimally invasive AAOCA repair may be appealing, although surgeons should be cautious given the high conversion rate.

Transition to Ductal Stenting for Single Ventricle Patients Led to Improved Survival: An Institutional Case Series

BACKGROUND

The use of systemic-to-pulmonary shunts (SPS) in neonates with single ventricle heart defects and ductal-dependent pulmonary blood flow (ddPBF) was historically associated with high morbidity and mortality at our center. As a result, we transitioned to the preferential use of ductus arteriosus stents (DS) when feasible. This report describes our initial results with this strategy.

METHODS

A single-center study of single ventricle patients that received DS or SPS from 2015 to 2019 was performed to assess whether DS was associated with decreased in-hospital morbidity and increased survival to stage II palliation.

RESULTS

A total of 34 patients were included (DS = 11; SPS = 23). Underlying cardiac anomalies were similar between groups and included pulmonary atresia, unbalanced atrioventricular septal defect, and tricuspid atresia. Procedure success was similar between groups (82% vs 83%). Two DS patients were converted to SPS, due to ductal vasospasm or pulmonary artery obstruction, and four SPS patients required surgical shunt revision. In DS patients, postprocedure mechanical ventilation duration was shorter (one vs three days, P = .009) and fewer required postprocedure extracorporeal membrane oxygenation (9% vs 39%, P = .11). A higher proportion of DS patients survived to stage II palliation (100% vs 64%, P = .035), and the probability of one-year survival was higher in DS patients (100% vs 61%, P = .02).

CONCLUSIONS

At our center, patients with single ventricle heart defects and ddPBF that received DS experienced reduced in-hospital morbidity and increased survival to stage II palliation compared to SPS.

Aortic valve repair with a newly approved geometric annuloplasty ring in patients undergoing proximal aortic repair: early results from a single-centre experience

OBJECTIVES

Aortic insufficiency (AI) is common in patients with proximal aortic disease, but limited options exist to facilitate aortic valve repair (AVr) in this population. This study reports 'real-world' early results of AVr using newly FDA-approved trileaflet and bicuspid geometric annuloplasty rings for patients with AI undergoing proximal aortic repair (PAR) in a single referral centre.

METHODS

All patients undergoing AVr with a rigid internal geometric annuloplasty ring (n = 47) in conjunction with PAR (ascending +/- root +/- arch) were included. Thirty-six patients underwent AVr with a trileaflet ring, and 11 patients underwent AVr with a bicuspid ring. The rings were implanted in the subannular position, and concomitant leaflet repair was performed if required for cusp prolapse identified after ring placement.

RESULTS

The median age was 58 years [interquartile range (IQR) 46-70]. PAR included supracoronary ascending replacement in 26 (55%) patients and remodelling valve-sparing root replacement with selective sinus replacement in 20 (42%) patients. Arch replacement was performed in 38 (81%) patients, including hemi-arch in 34 patients and total arch in 4 patients. There was no 30-day/in-hospital mortality. Preoperative AI was 3-4+ in 37 (79%) patients. Forty-one (87%) patients had zero-trace AI on post-repair transoesophageal echocardiography, and 6 patients had 1+ AI. The median early post-repair mean gradient was 13 mmHg (IQR 5-20). Follow-up imaging was available in 32 (68%) patients at a median of 11 months (IQR 10-13) postsurgery. AI was ≤1+ in 97% of patients with 2+ AI in 1 patient. All patients were alive and free from aortic valve reintervention at last follow-up.

CONCLUSIONS

Early results with geometric rigid internal ring annuloplasty for AVr in patients undergoing PAR appear promising and allow a standardized approach to repair with annular diameter reduction and cusp plication when needed. Longer-term follow-up will be required to ensure the durability of the procedure.

Borrowing from Adult Cardiac Surgeons-Bringing Congenital Heart Surgery Up to Speed in the Minimally Invasive Era

The majority of congenital and adult cardiac surgery is performed through a median sternotomy. For surgeons, this incision provides excellent exposure; however, for patients, a median sternotomy confers a poorer cosmetic outcome and the possibility of postoperative respiratory dysfunction, chronic pain, and deep sternal wound infections. Despite the advances in adult cardiac surgery, the use of minimally invasive techniques in pediatric patients is largely limited to small case series and less complex repairs. In this article, we review the risks, benefits, and limitations of the minimally invasive congenital cardiac approaches being performed today. The interest in these approaches continues to grow as more data supporting reduced morbidity, decreased length of stay, and faster recovery are published. In the future, as the technology and surgical familiarity improve, these alternative approaches will become more common, and may someday become the standard of care.

Implantation of a HeartMate 3 ventricular assist device in a 21-kg pediatric patient with Fontan failure

AIMS

The HeartMate 3 (HM3) ventricular assist device (VAD) is gaining popularity in adults due to a favorable risk profile. However, reports of HM3 use in children are limited, potentially due to concerns with device size.

MATERIALS AND METHODS

Here we report the successful use of an HM3-VAD as a bridge to transplantation in a 21 kg (BSA 0.84), an 8-year-old male child with Fontan failure on home inotropes.

RESULTS

Urgent VAD implantation was performed. The standard adult sewing ring was used. The tricuspid valve and papillary muscles were completely excised from the ventricular cavity to prevent inflow obstruction. The pump was placed in the left pleural space. Outflow graft and driveline implantation were routine. VAD function appeared excellent with a reduction in Fontan pressures and improved kidney and liver function. Reoperation was required once to rule out tamponade and twice to evacuate a recurrent right hemothorax. The patient was discharged 3 months later in good condition and underwent successful heart transplantation 10 months after VAD placement.

DISCUSSION

This report demonstrates the feasibility of HM3-VAD implantation in a 21-kg Fontan patient, suggesting HM3 size is not a prohibitive limitation at this weight.

Sustained Total All-Region (STAR) perfusion for Norwood reconstruction with complex intracardiac repair

We present the case of a newborn with complex congenital heart disease who was treated with a neonatal Norwood operation and total anomalous pulmonary venous return repair. During the Norwood reconstruction, a novel technique was utilized to perfuse the head, lower body, and heart continuously to minimize ischemic injury.

Overcoming underpowering: Trial simulations and a global rank end point to optimize clinical trials in children with heart disease

BACKGROUND

Randomized controlled trials (RCTs) in children with heart disease are challenging and therefore infrequently performed. We sought to improve feasibility of perioperative RCTs for this patient cohort using data from a large, multicenter clinical registry. We evaluated potential enrollment and end point frequencies for various inclusion cohorts and developed a novel global rank trial end point. We then performed trial simulations to evaluate power gains with the global rank end point and with use of planned covariate adjustment as an analytic strategy.

METHODS

Data from the Society of Thoracic Surgery-Congenital Heart Surgery Database (STS-CHSD, 2011-2016) were used to support development of a consensus-based global rank end point and for trial simulations. For Monte Carlo trial simulations (n = 50,000/outcome), we varied the odds of outcomes for treatment versus placebo and evaluated power based on the proportion of trial data sets with a significant outcome (P < .05).

RESULTS

The STS-CHSD study cohort included 35,967 infant index cardiopulmonary bypass operations from 103 STS-CHSD centers, including 11,411 (32%) neonatal cases and 12,243 (34%) high-complexity (Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery mortality category ≥4) cases. In trial simulations, study power was 21% for a mortality-only end point, 47% for a morbidity and mortality composite, and 78% for the global rank end point. With covariate adjustment, power increased to 94%. Planned covariate adjustment was preferable to restricting to higher-risk cohorts despite higher event rates in these cohorts.

CONCLUSIONS

Trial simulations can inform trial design. Our findings, including the newly developed global rank end point, may be informative for future perioperative trials in children with heart disease.