Management of the bad atrioventricular valve in Fontan…time for a change

Surgical Considerations in Adult Congenital Heart Disease Heart Failure

Surgical intervention is often used in the management of heart failure in patients with adult congenital heart disease. This review addresses anatomic variations and complications due to prior surgical interventions, including sternal reentry, collateral vessels, and the neo-aortic root after the Damus-Kaye-Stansel procedure. Surgical considerations for systemic atrioventricular valvular surgery, Fontan revision, and advanced heart failure therapies including ventricular assist devices, heart transplant, and combined heart-liver transplant are discussed, with a focus on unique patient populations including those with systemic right ventricles and those with Fontan circulation.

Evaluating the Prevalence and Factors Associated With an Optimal Neurodevelopmental Outcome in 4- to 6-Year-Old Children With Fontan Circulation

BACKGROUND

We sought to evaluate the prevalence and factors associated with "optimal" neurodevelopmental outcomes in 4- to 6-year-old children with Fontan circulation.

METHODS

Patients followed through the Western Canadian Complex Pediatric Therapies Follow-Up Program, and born between September 1996 and December 2015, were included. Optimal neurodevelopmental outcome was defined as full-scale intelligence quotient; visual-motor integration; adaptive behaviour assessment system-general adaptive composite scores of ≥ 80 each; and the absence of chronic motor disability, permanent hearing loss, visual impairment, and seizure disorder. Multivariable regression models and decision algorithms evaluated variables associated with optimal outcomes.

RESULTS

The Fontan procedure was completed on 225 children, with neurodevelopmental outcome data available for 205 (mean [standard deviation]) age at Fontan 3.4 (0.9) years, 37% female). Optimal neurodevelopmental outcome was identified in 55% (112 of 205). Factors independently associated with optimal neurodevelopmental outcome were female sex (odds ratio [OR], 2.1; 95% confidence interval [CI] 1.1-4.1), years of maternal schooling (OR, 1.2 [1.1-1.4]), age at Fontan (years) (OR, 0.97 [0.94-1.0]), need for concomitant atrioventricular valve (AVV) intervention (OR, 0.4 [0.2-1.0]), and time (hours) for lactate to be ≤ 2 mmol/L (OR, 0.9 [0.8-1.0]). Of those with Fontan completion < 3.25 years, without concomitant AVV intervention and lactate normalization within 8 hours post-Fontan, 87% (27 of 31) had optimal neurodevelopmental outcomes.

CONCLUSIONS

Optimal neurodevelopmental outcome was present in more than one-half of 4- to 6-year-old children with Fontan circulation in this cohort study, with important associated factors identified, including potentially modifiable factors such as younger age at Fontan surgery and lack of concomitant AVV intervention.

Atrioventricular septal defect in Fontan circulation: Right ventricular dominance, not valve surgery, adversely affects survival

OBJECTIVE

The effect of ventricular dominance and previous atrioventricular valve (AVV) surgery on patient outcomes after Fontan operation remains unclear. We sought to determine the effect of ventricular dominance and previous AVV surgery on transplantation-free survival and long-term AVV competency in patients with atrioventricular septal defect (AVSD) and Fontan circulation.

METHODS

We conducted a retrospective study of 1703 patients in the Australia and New Zealand Fontan Registry, who survived Fontan operation between 1987 and 2021.

RESULTS

Of 174 patients with AVSD, 60% (105/174) had right ventricular (RV) dominance and 40% (69/174) had left ventricular (LV) dominance. The cumulative incidence of moderate or greater AVV regurgitation at 25 years after Fontan operation in patients with LV dominance was 56% (95% CI, 35%-72%), compared with 54% (95% CI, 40%-67%) in patients with RV dominance (P = .6). Nonetheless, transplantation-free survival at 25 years in patients with LV dominance was 94% (95% CI, 86%-100%), compared with 67% (95% CI, 52%-87%) in patients with RV dominance (hazard ratio, 5.9; 95% CI, 1.4-25.4; P < .01). Of note, transplantation-free survival was not different in patients who underwent AVV surgery before or at Fontan completion compared with those who did not (15 years: 81% [95% CI, 62%-100%] vs 88% [95% CI, 81%-95%]; P = .3).

CONCLUSIONS

In patients with AVSD and Fontan circulation the rate of moderate or greater common AVV regurgitation is similar in those with LV and RV dominance. RV dominance, rather than previous AVV surgery, is a risk factor for death or transplantation.

Mechanical tricuspid valve replacement in hypoplastic left heart syndrome: An institutional experience

Objective

Atrioventricular valvar regurgitation in patients with single ventricles is associated with worse outcomes. Valve repair or replacement has been undertaken in an attempt to reduce mortality and morbidity. Current data on valve replacement in single ventricle patients are limited and derived from heterogenous populations. We describe our experience with repair and replacement of the tricuspid valve in children undergoing single ventricle palliation for hypoplastic left heart syndrome.

Methods

We included 27 patients with hypoplastic left heart syndrome with at least moderate tricuspid regurgitation who underwent valve intervention between 2007 and 2021 at our institution; charts were retrospectively reviewed for data.

Results

Eleven patients (73% male) underwent valve replacement (median age, 3 years). Preoperative ventricular systolic function was normal in 10 patients (91%). Median follow-up postoperatively was 4 years with no early mortality, 1 (9%) late mortality, and 1 heart transplant (9%). Morbidity consisted of complete heart block in 1 patient (9%), with no important hemorrhagic or thrombotic events. Among survivors of replacement (n = 9), ventricular function was preserved in all (n = 8) who had normal function preoperatively and improved in the remaining patient. Sixteen patients underwent valve repair (median age, 4 months) with no early mortality, 8 (50%) midterm mortalities, and 2 heart transplants (12%).

Conclusions

Tricuspid valve replacement is a feasible option in hypoplastic left heart syndrome with significant tricuspid regurgitation, with favorable outcomes in the intermediate follow-up. When undertaken in the setting of normal function, ventricular function may be preserved in up to 80% of patients. Long-term follow-up is needed.

Late Fontan Circulatory Failure. What Drives Systemic Venous Congestion and Low Cardiac Output in Adult Fontan Patients?

The Fontan circulation provides definite palliation for children born with a single anatomical or functional ventricle by diverting systemic venous blood directly to the pulmonary arteries, effectively rendering systemic venous return into portal vessels to the lung. Although this restores pulmonary blood flow and avoids the mixture of oxygenated and deoxygenated blood, it also results in elevated systemic venous pressures and low cardiac output. These are the two hallmarks of any Fontan circulation and the cause of Fontan circulatory failure later in life. We highlight the determinants of systemic venous return, its changed relationship with the pulmonary circulation, how it affects preload, and the changed role of the heart (myocardium, valves, and heart rate). By critically evaluating the components of the Fontan circulation, we hope to give some clues in how to optimize the Fontan circulation and avenues for future research.

Management of circulatory failure after Fontan surgery

With improvement in survival after Fontan surgery resulting in an increasing number of older survivors, there are more patients with a Fontan circulation experiencing circulatory failure each year. Fontan circulatory failure may have a number of underlying etiologies. Once Fontan failure manifests, prognosis is poor, with patient freedom from death or transplant at 10 years of only about 40%. Medical treatments used include traditional heart failure medications such as renin-angiotensin-aldosterone system blockers and beta-blockers, diuretics for symptomatic management, antiarrhythmics for rhythm control, and phosphodiesterase-5 inhibitors to decrease PVR and improve preload. These oral medical therapies are typically not very effective and have little data demonstrating benefit; if there are no surgical or catheter-based interventions to improve the Fontan circulation, patients with severe symptoms often require inotropic medications or mechanical circulatory support. Mechanical circulatory support benefits patients with ventricular dysfunction but may not be as useful in patients with other forms of Fontan failure. Transplant remains the definitive treatment for circulatory failure after Fontan, but patients with a Fontan circulation face many challenges both before and after transplant. There remains significant room and urgent need for improvement in the management and outcomes of patients with circulatory failure after Fontan surgery.

Melody valve-in-valve implantation in the tricuspid position through a Fontan conduit fenestration

Patients with single right ventricle and tricuspid regurgitation have increased morbidity and mortality rates. The outcomes of surgical tricuspid valve repair and replacement are dismal. Although some centers prefer valve replacement with a bioprosthetic valve in the tricuspid position for the pediatric population, these valves have limited longevity and will eventually need to be replaced. Unfortunately, single ventricle patients are fragile and unlikely to tolerate a second replacement. Percutaneous valve-in-valve (ViV) implantation is an acceptable alternative with low morbidity and mortality. Studies have also shown acceptable short- and mid-term outcomes. We report a case of Melody ViV placement in the tricuspid position in a patient with hypoplastic left heart syndrome through the fenestration of a Fontan conduit.

Systemic Semilunar Valve Repair/Replacement With Fontan Circulation: The Mayo Clinic Experience

Background: There is a paucity of literature regarding systemic semilunar valve (SSLV) dysfunction in patients with Fontan circulation. We sought to describe our center's 47-year experience with systemic semilunar valve replacement or repair (SSLVR) in patients with Fontan circulation. Methods: The Mayo Clinic Fontan Database is a comprehensive institutional database that stores clinical information of 1176 patients from 1973 to 2021. It was reviewed to identify patients who had a SSLV intervention at the time of or after Fontan. A cohort of 15 patients was identified and a retrospective review of their records was performed. Results: Fourteen patients had SSLV replacement (all mechanical) and one had a repair. SSLVR occurred up to 29 years following the Fontan (mean 11.3 ± 9 years, median 14 years). Thirteen of 14 with SSLVR were performed after Fontan and one was done at the time of initial Fontan. This was an older cohort and mean age at the time of Fontan was 8.7 ± 9.4 years (median 4 years). Indication for the operation was > moderate SSLV regurgitation in all patients. Six patients had decreased ventricular function (EF < 50%) prior to SSLVR and 8 had reduced function after SSLVR. Conclusion: Fortunately, the need for SSLV intervention after Fontan was rare, as evidenced by our small cohort extracted from a large single-institution database spanning a 47-year time period. Reduced preoperative and postoperative ejection fraction was common but did not seem to impact the outcome. Optimal timing for SSLV intervention after Fontan remains unclear.

Long-term results of concomitant atrioventricular valve intervention and the Fontan operation

OBJECTIVES

The optimal timing for atrioventricular valve (AVV) repair in patients with a Fontan circulation remains controversial. Few studies have reported the long-term outcomes of AVV repair concomitant with a Fontan operation.

METHODS

From January 2006 to December 2018, a total of 89 patients who developed moderate or severe AVV regurgitation before a Fontan operation were divided into 2 groups: group 1, including 37 patients who did not undergo concomitant AVV repair; and group 2, including 52 patients who received AVV repair concomitant with a Fontan operation.

RESULTS

The mean age at the time of the Fontan operation was 6.74 years for group 1 and 8.96 years for group 2, respectively. Early death occurred in 3 patients [2 patients (5.4%) in group 2, patient 1 (1.9%) in group 1]. Freedom from long-term death, cardiac function reduction and protein-losing enteropathy were similar among the 2 groups. Common AVV function was apparently poorer than mitral valve function after repair [hazard ratio (HR) 3.83, 95% confidence interval (CI) 1.31-11.17; P = 0.014]. The occurrence of AVV valve failure in group 1 was lower than that in group 2 (HR 0.44, 95% CI 0.22-0.91; P = 0.026). AVV function became worse during the follow-up period than that at discharge in both groups (P = 0.03 in group 1 and P = 0.001 in group 2).

CONCLUSIONS

The long-term results of AVV repair concomitant with a Fontan operation are favourable.

Effect of Earlier Atrioventricular Valve Intervention on Survival After the Fontan Operation

Whereas the prevalence and impact of atrioventricular valve (AVV) regurgitation in patients with single ventricle physiology has become increasingly apparent, the optimal timing for valve intervention is unclear. To investigate this, we performed a retrospective review of all 1,167 patients from the Mayo Clinic Fontan database. Thirteen percent (153 patients) had AVV repair or replacement during their staged single ventricle palliation. We found that patients with right ventricular morphology and common AVV were at increased risk for AVV intervention. Patients who underwent AVV intervention had increased risk of death/transplant compared with those who did not (hazards ratio [HR] = 1.75, 95% CI 1.37 to 2.23, p <0.001). With respect to valve intervention timing, whereas AVV intervention before Fontan presented similar risk for death/transplant compared with no AVV intervention (HR = 0.85, 95% CI 0.32 to 2.27, p = 0.74), intervention at time of Fontan had a significantly higher risk (HR = 1.46, 95% CI 1.09 to 1.97, p = 0.01), and intervention after Fontan had a much more substantial risk (HR = 3.83, 95% CI 2.54 to 5.79, p <0.001). AVV repair failure occurred in 11% of patients. In terms of relative risk of valve repair versus replacement, in post-Fontan AVV intervention patients, AVV replacement carried a 2.9 fold risk of death/transplant compared with AVV repair. In conclusion, AVV disease remains a considerable challenge for durable Fontan physiology. This data demonstrates that earlier intervention on valve pathology improves survival with the Fontan circulation. Continued surveillance of single ventricle patients and prompt referral of those with valve pathology can improve outcomes in this challenging population.

Pathologic Characteristics of 119 Archived Specimens Showing the Phenotypic Features of Hypoplastic Left Heart Syndrome

To assess the phenotypic variations found among hearts diagnosed at autopsy with hypoplastic left heart syndrome, with attention to implications related to this syndrome as an acquired disease of fetal life, rather than being the consequence of abnormal embryogenesis. We assessed 119 specimens, from 2 archives, diagnosed initially as representing hypoplastic left heart syndrome. Among the 119 specimens, the majority of which had been entered into the archives prior to the availability of surgical treatment for the syndrome, 36 (30%) had the combination of mitral and aortic atresia, 26 (22%) had mitral and aortic stenosis, and 57 (48%) had mitral stenosis combined with aortic atresia. Of the hearts with combined atresia, 92% (33 specimens) had slit-like left ventricles, compared to 12% (3 specimens) of hearts with stenosis of both aortic and mitral valves, and 2 hearts (4%) with mitral stenosis and aortic atresia (P < 0.001). Hypoplasia of the left atrial appendage was present in half (18 specimens, 51%) of those with combined atresia, as opposed to just 18% (10 specimens) of mitral stenosis combined with aortic atresia (P = 0.001). Small left ventricles with valves deemed proportional in size were found in 11 (42%) of those with combined mitral and aortic stenosis. Fibroelastosis was significantly more common in the hearts with mitral stenosis compared to those with mitral atresia (76% vs 11%, P < 0.001). The ascending aorta was significantly smaller in the hearts with aortic atresia. The variability in the morphologic findings support the notion that the lesions seen represent acquired disease occurring subsequent to closure of the embryonic interventricular communication, rather than representing abnormal embryogenesis.