Dilatation and Dysfunction of the Neo-aortic Root and in 76 Patients After the Ross Procedure

Biomechanical Analysis of the Ross Procedure in an Ex Vivo Left Heart Simulator

BACKGROUND

Neo-aortic pulmonary autografts often experience root dilation and valve regurgitation over time. This study seeks to understand the biomechanical differences between aortic and neo-aortic pulmonary roots using a heart simulator.

METHODS

Porcine aortic, neo-aortic pulmonary, and pulmonary roots (n  =  6) were mounted in a heart simulator (parameters: 100 mm Hg, 37 °C, 70 cycles per minute, 5.0 L/min cardiac output). Echocardiography was used to study root distensibility (percentage change in luminal diameter between systole and diastole) and valve function. Leaflet motion was tracked with high-speed videography. After 30 min in the simulator, leaflet thickness (via cryosectioning), and multiaxial modulus (via lenticular hydrostatic deformation testing) were obtained.

RESULTS

There were no significant differences between aortic and neo-aortic pulmonary leaflet motion, including mean opening velocity (218 vs 248 mm/s, P  =  .27) or mean closing velocity (116 vs 157 mm/s, P  =  .12). Distensibility was similar between aortic (8.5%, 1.56 mm) and neo-aortic pulmonary (7.8%, 1.12 mm) roots (P  =  .59). Compared to virgin controls, native pulmonic roots exposed to systemic pressure for 30 min had reduced leaflet thickness (630 vs 385 µm, P  =  .049) and a reduced Young's modulus (3,125 vs 1,089 kPa, P  =  .077). In contrast, the aortic roots exposed to pressure displayed no significant difference in aortic leaflet thickness (1,317 vs 1,256 µm, P  =  .27) or modulus (5,931 vs 3,631 kPa, P  =  .56).

CONCLUSIONS

Neo-aortic pulmonary roots demonstrated equivalence in valve function and distensibility but did experience changes in biomechanical properties and morphology. These changes may contribute to long-term complications associated with the Ross procedure.

Reconstruction of right ventricular outflow tract stenosis and right ventricular failure after Ross procedure - comprehensive assessment of adult congenital heart disease with four-dimensional imaging: a case report

BACKGROUND

Re-intervention after Ross procedure into the right ventricular outflow tract might be needed in patients in the long term. However, right ventricular outflow tract re-intervention indications are still unclear. Comprehensive assessment of total hemodynamics is needed. A 42-year-old Japanese woman was referred to our hospital for moderately severe pulmonary regurgitation and severe tricuspid regurgitation after a Ross-Konno procedure. Thirteen years after surgery, she developed atrial fibrillation and atrial flutter and complained of dyspnea. Electrophysiological studies showed re-entry circuit around the low voltage area of the lateral wall on the right atrium. Four-dimensional flow magnetic resonance imaging revealed moderate pulmonary regurgitation, severe tricuspid regurgitation, and a dilated right ventricle. Flow energy loss in right ventricle calculated from four-dimensional flow magnetic resonance imaging was five times higher than in normal controls, suggesting an overload of the right-sided heart system. Her left ventricular ejection fraction was almost preserved. Moreover, the total left interventricular pressure difference, which shows diastolic function, revealed that her sucking force in left ventricle was preserved. After the comprehensive assessments, we performed right ventricular outflow tract reconstruction, tricuspid valve annuloplasty, and right-side Maze procedure. A permanent pacemaker with a single atrial lead was implanted 14 days postoperatively. She was discharged 27 days postoperatively. Echocardiography performed 3 months later showed that the size of the dilated right ventricle had significantly reduced.

DISCUSSION

A four-dimensional imaging tool can be useful in the decision of re-operation in patients with complex adult congenital heart disease. The optimal timing of surgery should be considered comprehensively.

Autograft remodeling after the Ross procedure by cardiovascular magnetic resonance imaging: Aortic stenosis versus insufficiency

BACKGROUND

Studies suggest that patients undergoing the Ross procedure for aortic insufficiency are at greater risk of autograft dilatation than those with aortic stenosis. By using a tailored Ross technique to mitigate autograft dilatation in patients with aortic insufficiency, we aimed to compare the biomechanical and morphologic remodeling of the autograft at 1 year between patients with aortic insufficiency and patients with aortic stenosis.

METHODS

A total of 210 patients underwent a Ross procedure (2011-2016). Of those, 86 patients (mean age 43 ± 13 years; 32% were female) completed preoperative and postoperative cardiovascular magnetic resonance imaging. A total of 71 studies were suitable for analysis: 41 patients with aortic stenosis and 30 patients with aortic insufficiency. Nine healthy adults were used as controls. Autograft root dimensions, individual sinus volumes, and distensibility were measured using cardiovascular magnetic resonance.

RESULTS

At 1 year, there was no difference in autograft root dimensions between patients with aortic stenosis (mean annulus 25.1 ± 3.1 mm and sinus diameters 35 ± 4.1 mm) and patients with aortic insufficiency (26.6 ± 3 mm and 37.1 ± 3.5 mm; P = .12 and .06, respectively). Relative sinus of Valsalva volumes were symmetrical in the aortic stenosis (right 34.8% ± 4%, left 33.7% ± 3.5%, noncoronary 31.4% ± 3.2%) and aortic insufficiency groups (34.8% ± 3.9%, 33.8% ± 2.8%, 31.3% ± 3.7%, P = .85, .92, and .82), and similar to those of healthy adults. Aortic root distensibility was reduced in both groups compared with healthy adults (P = .003), but was similar between aortic stenosis (3.12 ± 1.58 × 10^-3 mm Hg^-1) and aortic insufficiency (3.04 ± 1.15 × 10^-3 mm Hg^-1; P = .9).

CONCLUSIONS

Using a tailored technique, there were no differences in the morphologic or biomechanical remodeling of the autograft root 1 year after the Ross procedure between patients with aortic stenosis and patients with aortic insufficiency. However, autograft roots are stiffer than native aortic roots.

Mid-term Outcome of 100 Consecutive Ross Procedures: Excellent Survival, But Yet to Be a Cure

The Ross procedure offers excellent short-term outcome but the long-term durability is under debate. Reinterventions and follow-up of 100 consecutive patients undergoing Ross Procedure at our centre (1993-2011) were analysed. Follow-up was available for 96 patients (97%) with a median duration of 5.3 (0.1-17.1) years. Median age of the patient cohort was 15.2 (0.04-58.4) years with 76 males. 93% had underlying congenital aortic stenosis. Root replacement technique was applied in all. The most common valved conduits used for reconstruction of the right ventricular outflow tract were homografts (66 patients) and bovine jugular vein (Contegra^R) graft (31 patients). Additional procedures included Ross-Konno procedure (14%), resection of subaortic stenosis/myectomy (11%) and reduction plasty of the ascending aorta (25%). One patient died within the first 30 days (1%). Late deaths occurred in 4 patients (4%) 0.5-4.5 years postoperatively: causes included pulmonary hypertension due to endocardial fibroelastosis (2), subarachnoid haemorrhage (1) and sudden cardiac death (1). Five-year survival was 93.6 (95% CI 88.1-99.1)%. Moderate or severe aortic (autograft) regurgitation needing reoperation occurred in 8 patients with a 5-year freedom from autograft reoperation of 98.5 (95.6-100)%. Five-year freedom from reintervention (surgery or catheter based) on the right ventricular outflow tract conduit was 91.5 (85.5-96.5)%. Univariate predictors of this reinterventions were smaller graft size (p = 0.03) and use of a Contegra^R graft (p = 0.04). Ross procedure can be performed with low mortality and good survival in the long term. Most of the reinterventions are related to the neo-right ventricular outflow tract and may be partly attributed to the lack of growth. While the Ross Procedure remains an invaluable option for aortic valve disease in children, new solutions for the neo-pulmonary valve as well as for the less often occurring problems on the autograft are needed.