Pulmonary Flow Management by Combination Therapy of Hemostatic Clipping and Balloon Angioplasty for Right Ventricular-Pulmonary Artery Shunt in Hypoplastic Left Heart Syndrome

Controlling pulmonary blood flow in patients who have undergone Norwood palliation, especially early postoperatively, is challenging due to a change in the balance of systemic and pulmonary vascular resistance. We applied a combination therapy of clipping and balloon angioplasty for right ventricle-pulmonary artery (RV-PA) shunt to control pulmonary blood flow, but the influence of the combination therapy on the PA condition is uncertain. Retrospectively analysis was conducted of all infants with hypoplastic left heart syndrome who had undergone Norwood palliation with RV-PA shunt at Okayama University Hospital from January 2008 to September 2022. A total of 50 consecutive patients underwent Norwood palliation with RV-PA shunt in this study period. Of them, 29 patients underwent RV-PA shunt flow clipping, and the remaining 21 had unclipped RV-PA shunt. Twenty-three patients underwent balloon angioplasty for RV-PA shunt with clips. After balloon angioplasty, oxygen saturation significantly increased from 69 (59-76)% to 80 (72-86)% (p < 0.001), and the narrowest portion of the clipped conduit significantly improved from 2.8 (1.8-3.4) to 3.8 (2.9-4.6) mm (p < 0.001). In cardiac catheterizations prior to Bidirectional cavo-pulmonary shunt (BCPS), there were no significant differences in pulmonary-to-systemic flow ratio (Qp/Qs), ventricular end-diastolic pressure, Nakata index, arterial saturation, mean pulmonary artery pressure and pulmonary vascular resistance index. On the other hand, in Cardiac catheterizations prior to Fontan, Nakata index was larger in the clipped group (p = 0.02). There was no statistically significant difference in the 5-year survival between the two groups (clipped group 96%, unclipped group 74%, log-rank test: p = 0.13). At least, our combination therapy of clipping and balloon angioplasty for RV-PA shunt did not negatively impact PA growth. Although there is a trend toward better but not statistically significant difference in outcomes in the clipped group compared to the non-clipped group, this treatment strategy may play an important role in improving outcomes in hypoplastic left heart syndrome.

Outcomes of extracardiac Fontan operation: A single institution experience with 398 patients

OBJECTIVE

The study objective was to evaluate the outcomes of the extracardiac Fontan operation at a single institution.

METHODS

We conducted a retrospective study of 398 patients from a single institution who underwent their initial extracardiac Fontan operation between 1997 and 2020. We determined the incidence of and risk factors for failure of the Fontan circulation, which includes death, Fontan takedown, heart transplantation, protein-losing enteropathy, plastic bronchitis, and functional status at the last follow-up.

RESULTS

The median follow-up time was 10.3 years (interquartile range, 6.4-14.6). The overall survival was 96% and 86% at 10 and 20 years after extracardiac Fontan operation, respectively. There were 6 early deaths (6/398, 1.5%) and 15 late deaths (15/398, 3.8%). Forty-nine patients (12.5%) developed failure of the Fontan circulation. Freedom from the failure of Fontan circulation was 88% at 10 years and 76% at 20 years. Risk factors for failure of the Fontan circulation were right ventricular dominance (hazard ratio, 4.7; P < .001; 95% CI, 2.1-10.5), aortic atresia (hazard ratio, 5.5; P < .001; 95% CI, 2.3-12.8), and elevated mean pulmonary artery pressure (hazard ratio, 2.3; P = .002; 95% CI, 1.2-6.7).

CONCLUSIONS

Rates of failure of the Fontan circulation are low after the contemporary extracardiac Fontan operation. Risk factors for failure of the extracardiac Fontan circulation include right ventricular dominance, aortic atresia, and elevated pulmonary artery pressures.

Surgical Modulation of Pulmonary Artery Shear Stress: A Patient-Specific CFD Analysis of the Norwood Procedure

PURPOSR

This study created 3D CFD models of the Norwood procedure for hypoplastic left heart syndrome (HLHS) using standard angiography and echocardiogram data to investigate the impact of shunt characteristics on pulmonary artery (PA) hemodynamics. Leveraging routine clinical data offers advantages such as availability and cost-effectiveness without subjecting patients to additional invasive procedures.

METHODS

Patient-specific geometries of the intrathoracic arteries of two Norwood patients were generated from biplane cineangiograms. "Virtual surgery" was then performed to simulate the hemodynamics of alternative PA shunt configurations, including shunt type (modified Blalock-Thomas-Taussig shunt (mBTTS) vs. right ventricle-to-pulmonary artery shunt (RVPAS)), shunt diameter, and pulmonary artery anastomosis angle. Left-right pulmonary flow differential, Qp/Qs, time-averaged wall shear stress (TAWSS), and oscillatory shear index (OSI) were evaluated.

RESULTS

There was strong agreement between clinically measured data and CFD model output throughout the patient-specific models. Geometries with a RVPAS tended toward more balanced left-right pulmonary flow, lower Qp/Qs, and greater TAWSS and OSI than models with a mBTTS. For both shunt types, larger shunts resulted in a higher Qp/Qs and higher TAWSS, with minimal effect on OSI. Low TAWSS areas correlated with regions of low flow and changing the PA-shunt anastomosis angle to face toward low TAWSS regions increased TAWSS.

CONCLUSION

Excellent correlation between clinically measured and CFD model data shows that 3D CFD models of HLHS Norwood can be developed using standard angiography and echocardiographic data. The CFD analysis also revealed consistent changes in PA TAWSS, flow differential, and OSI as a function of shunt characteristics.

Journey Toward Improved Long-Term Outcomes After Norwood-Sano Procedure: Focus on the Aortic Arch Reconstruction

The disadvantage of right ventricle-to-pulmonary artery (RV-PA) shunt is the need for more unplanned interventions to address stenosis in the shunt or branch pulmonary arteries, as compared to the modified Blalock-Taussig shunt group. Ring-enforced RV-PA PTFE conduit and dunk technique minimized these complications and right ventricle (RV) damage. Aortic arch obstruction increases afterload and leads to ventricular dysfunction and tricuspid regurgitation; therefore, most surgeons prefer to use homograft, autologous pericardium, or bovine pericardium to reconstruct the neoaorta. Artificial materials decrease the elastic properties, increase wall stiffness, and decrease the distensibility of the aorta; and as a result, RV function gradually deteriorates. This inelastic reconstructed aorta may be one of the reasons why long-term outcomes after the Fontan procedure are worse in hypoplastic left heart syndrome (HLHS) patients, in comparison to non-HLHS. Reconstruction of the neoaorta without any patch materials, or at least techniques that largely minimize the use of non-autologous materials, will offer a further refinement of our ability to optimize ventriculoarterial coupling and thereby long-term RV function.

Impact of Medical Interventions and Comorbidities on Norwood Admission for Patients with Hypoplastic Left Heart Syndrome

The purpose of these analyses was to determine how specific comorbidities and medical interventions impact risk of inpatient mortality in those with hypoplastic left heart syndrome undergoing Norwood procedure. The secondary aims were to determine the impact of these on billed charges, postoperative length of stay, and risk of cardiac arrest. Admissions from 2004 to 2015 in the Pediatric Health Information System database with hypoplastic left heart syndrome and Norwood procedure were identified. Admission characteristics, patient interventions, and the presence of comorbidities were captured. A total of 5,138 admissions were identified meeting inclusion criteria. Of these 829 (16.1%) experienced inpatient mortality, and 352 (6.7%) experienced cardiac arrest. The frequency of inpatient mortality did not significantly change over the course of the study era. The frequency of cardiac arrest significantly decreased from 7.4% in 2004 to 4.3% in 2015 (p = 0.04). The frequency of pharmacologic therapies, particularly vasoactive use, decreased as the study period progressed. Regression analyses demonstrated a significant association between cardiac arrest and inpatient mortality with arrhythmias, acute kidney injury, and pulmonary hypertension. Similarly, regression analyses demonstrated a significant association between increase in billed charges and length of stay with year of surgery, presence of heart failure, syndromes, and acute kidney injury. For patients with hypoplastic left heart syndrome undergoing the Norwood procedure, the frequency of pharmacologic therapies and cardiac arrest has decreased over time. There are significant associations between acute kidney injury, arrythmias, and pulmonary hypertension with cardiac arrest and mortality.

Outcomes of Norwood procedure with hypoplastic left heart syndrome: Our 12-year single-center experience

Background

In this study, we aimed to analyze the predictors and risk factors of mortality in patients who underwent Norwood I procedure with the diagnosis of hypoplastic left heart syndrome.

Methods

Between January 2009 and December 2020, a total of 139 patients (95 males, 44 females) who underwent Norwood I procedure with the diagnosis of hypoplastic left heart syndrome in our center were retrospectively analyzed.

Results

The median birth weight was 3,200 (range, 3,000 to 3,350) g and the median age at the time of operation was seven (range, 5 to 10) days. Pulmonary flow was achieved with a Sano shunt in the majority (72%) of patients. Survival rate was 41% after the first stage. Reoperation for bleeding (p=0.017), reoperation for residual lesion (p=0.011), and postoperative peak lactate level (p=0.029), were associated with in-hospital mortality. Nineteen (33%) of 57 patients died before the second stage. Thirty-three (58%) patients underwent second stage, and survival after the second stage was 94%. Thirteen patients underwent third stage, and survival after the third stage was 85%. Estimated probability of survival at six months, and one, two, three, and four years were 33%, 33%, 25%, 25%, and 22% respectively.

Conclusion

Hospital and inter-stage mortality rates are still high and this seems to be the most challenging period in term of survival efforts of the patients with hypoplastic left heart syndrome. Early recognition and reintervention of anatomical residual defects, close follow-up in the inter-stage period, and the accumulation of multidisciplinary experience may help to improve the results to acceptable limits.

High Risk Status for Stage I Palliation Increases Mortality Following Stage II But Not Stage III

BACKGROUND

High risk (HR) factors have been shown to have increased rates of mortality following Stage 1 palliation (S1P) for single ventricle physiology. It remains unclear how initial HR status affects longitudinal outcomes following subsequent Stage 2 (S2P) and Stage 3 (S3P) palliation.

METHODS

Single ventricle patients undergoing S1P between July of 2004 and October of 2018 at a single institution were included. Patients having ≥ 1 HR factor were considered HR status, with all others classified as low risk (LR). Longitudinal survival stratified by risk status was compared following each palliative stage, in addition to re-admission and length of stay (LOS). Proportional hazard modeling was used to determine risk factors for longitudinal mortality.

RESULTS

Of 132 patients presenting during the study for S1P, 57 (43.2%) were classified as HR. Overall 10-year survival was decreased in the HR cohort (p=0.001). HR patients were at significantly increased risk of death during Interstage I (p=0.01) and Interstage II (p=0.01), but survival was similar to LR patients following S3P (p=0.31). Re-admission rates following S2P were higher among HR patients (41.9% vs 22.5%, p=0.029), but were similar following S3P. LOS was increased in the HR cohort following S2P (median 11 vs 9 days, p=0.024) but similar to the LR group following S3P. Prematurity was the risk factor most consistently associated with increased mortality following all stages.

CONCLUSIONS

HR status for patients undergoing S1P portends a higher risk of mortality, LOS, and re-admission following S2P. HR patients enjoy similar survival to low-risk patients following S3P.

Preoperative risk factors influencing inter-stage mortality after the Norwood procedure

OBJECTIVES

With improvements in early survival after the stage I palliation (S1P) Norwood procedure for hypoplastic left heart syndrome (HLHS) and its variants, inter-stage death accounts for an increasing proportion of mortality. Our aim was to identify the risk factors for inter-stage mortality.

METHODS

The records of 322 neonates with HLHS or a variant who underwent the Norwood procedure at our centre between 2001 and 2019 were retrospectively analysed.

RESULTS

The diagnoses included 271 neonates with HLHS (84%) and 51 with variants (16%). Aortic atresia was observed in 138 (43%) patients, mitral atresia in 91 (28%), extracardiac anomalies in 42 (13%) and genetic disorder in 14 (4%). The median age and weight of the patients at the S1P Norwood procedure were 9 (interquartile range: 7-12) days and 3.2 (2.9-3.5) kg, respectively. The median cardiopulmonary bypass time was 137 (107-163) min. Modified Blalock-Taussig shunts were used in 159 (49%) and unvalved right ventricle-to-pulmonary artery shunts in 163 (51%) patients. The number of inter-stage deaths was as follows: between S1P and stage II palliation (S2P), 61 including 38 early (<30 days) and 23 late (>30 days) deaths, and between S2P and stage III palliation, 32 deaths. Low birth weight (<2.5 kg) (odds ratio 4.37, P = 0.020) and restrictive atrial septum (odds ratio 2.97, P = 0.013) were identified as risks for early mortality. Low birth weight [hazard ratio (HR) 0.99/g, P = 0.002] was a risk for inter-stage mortality between S1P and S2P. Extracardiac anomalies (HR 4.75, P = 0.049) and significant pre-S1P atrioventricular valve regurgitation (HR: 7.72, P = 0.016) were risks for inter-stage mortality between S2P and stage III palliation. Other anatomical variables including aortic atresia, anatomical subtypes and the diameter of the ascending aorta nor shunt type were not identified as risk factors for mortality during any inter-stage period.

CONCLUSIONS

The risk factors for inter-stage attrition after the Norwood procedure were different between each stage. Preoperative factors, including birth weight, restrictive atrial septum and extracardiac anomalies, adversely affected the inter-stage mortality.

Does the size of pulmonary artery impact on recoarctation of the aorta after the Norwood procedure without patch?

OBJECTIVES

This study aimed to evaluate whether recoarctation of the aorta (reCoA) after the Norwood procedure for hypoplastic left heart syndrome correlates with pre- and postoperative anatomic factors.

METHODS

This retrospective study included 48 patients who underwent Norwood procedure with right ventricle-to-pulmonary artery conduit between 2009 and 2017. Anatomical factors such as preoperative length, diameter of the main pulmonary artery (MPA), and postoperative neoaortic arch angle stratified by arch reconstruction technique were analysed using the receiver operating characteristic analysis.

RESULTS

Eleven patients needed surgical intervention for reCoA at stage 2. Out of the 30 patients who underwent direct anastomosis during arch reconstruction, 7 developed reCoA. Seven patients received the full patch augmentation (patch augmentation for both lesser and greater curvatures) and were all spared from reCoA. Among the patients who had direct anastomosis, the preoperative MPA length was correlated with the postoperative arch angle (P = 0.021) and was associated with the occurrence of reCoA (P = 0.002) and the best cutoff value for MPA length was 10 mm. The postoperative arch angle was also correlated with the incidence of reCoA (P < 0.001) and was larger in patients who underwent the full patch augmentation than in patients who had direct anastomosis (126° vs 112°, P = 0.005) despite comparable MPA length.

CONCLUSIONS

ReCoA after the Norwood procedure correlates with MPA length when a direct anastomosis was used. Direct anastomosis can be considered in patients with a longer preoperative MPA. In other cases, the full patch augmentation should be considered for obtaining a large and smooth neoaortic arch.