Aortic valve replacement with pulmonary autograft in children and adults

The Quebec Heart Institute: 50 years of excellence in cardiology

The Quebec Heart Institute was established in 1957 at the Laval Hospital in Sainte-Foy, Quebec. Since then, clinical and research activities have made this Institute one of the largest tertiary care cardiology centres in Canada. With its vast catchment area of more than 3,000,000 people, the Institute has developed a strong collaboration with referral physicians centred on clinical, teaching and research interests. The Institute pioneered several aspects of cardiac surgery, invasive cardiology, echocardiography, basic research and, more recently, a network of researchers and clinicians working in the field of 'metabolic cardiology'. The first 50 years of the Quebec Heart Institute are depicted in this overview, which will also introduce this special supplement to The Canadian Journal of Cardiology.

Surgery for aortic stenosis in children: a 40-year experience

BACKGROUND

Aortic stenosis (AS) is encountered in approximately 5% of children with heart disease. The indications for surgery and the surgical techniques for AS are well established. This report focuses on the early and long-term outcomes in children with AS over a 40-year period.

METHODS

Included in this study were 508 patients ranging in ages from 1 day to 19 years, who were operated on for AS between 1960 and 2002. Eighty-one percent (414 of 508) of the patients had left ventricular outflow tract obstruction (LVOTO) at a single level: 40 supravalvar, 242 valvar (critical AS in 85 neonates and young infants and in 157 older children), and 132 subvalvar. Nineteen percent (94 of 508) of the patients had LVOTO at more than one level. Associated congenital cardiac defects were found in 32% of the patients.

RESULTS

The overall hospital mortality rate was 8% (40/508) with neonates with critical AS having the highest mortality (33%). The late mortality was 4% for the entire group. Follow-up was 95% complete. The mean follow-up was 8.5 +/- 7.1 years. In the subgroup with multilevel LVOTO (n = 94), the average intraoperative peak systolic left ventricular-aortic gradient decreased from 80 to 22 mm Hg after repair but increased progressively to 74 +/- 36 mm Hg (p < 0.05) before reintervention was required. One hundred twenty-one patients (24%) underwent 151 reoperations for recurrent or residual LVOTO or aortic regurgitation. Actuarial curves predict a 20-year survival of 88% and 62% freedom from reoperation for all patients with AS. Symptomatic improvement in survivors was excellent (90% New York Heart Association class I).

CONCLUSIONS

Surgical relief of LVOTO in infants and children can be accomplished with low mortality and morbidity. Neonates with critical AS have significantly higher mortality and morbidity due to their complex anatomy and their critical presentation that affects outcome. Aortic valvotomy delays valve replacement in a significant percentage of children. The Ross procedure and mechanical aortic valve replacements have had a low mortality and morbidity in our series. Valve replacement will eventually be required in most children presenting with valvar AS and multilevel LVOTO while repair of discrete subaortic stenosis and supravalvar AS may not require reoperation in most patients. Children with LVOTO should have lifetime follow-up.

Technique of pulmonary autograft aortic valve replacement in children (the Ross procedure)

Pulmonary autograft replacement has become a popular technique for relieving left ventricular outflow tract obstruction in children with aortic valvular or subvalvular disease. The advantages of the autograft are the avoidance of prosthetic valves that require anticoagulation and the potential for growth of a viable autograft aortic valve. Although many techniques for implantation of the autograft in the aortic outflow tract have been described, the most commonly preferred technique is the use of the autograft as a root replacement with reimplantation of the coronary ostia. This technique provides the optimal geometry of the autograft commissural attachments and also permits adjustment of the aortic annulus to enlarge the subaortic region in patients with complex left ventricular outflow tract obstruction or to narrow the aortic annulus in patients with primary aortic regurgitation and annular dilatation. Use of the autograft technique in children and young adults has resulted in excellent relief of outflow tract obstruction with low operative morbidity and mortality, and the intermediate results have been encouraging. The variations in surgical technique that have evolved have the potential to decrease the risk of late redilatation and regurgitation of the autograft valve and may provide better longevity. Copyright 1998 by W.B. Saunders Company

Perioperative conduction and rhythm disturbances after the Ross procedure in young patients

BACKGROUND

The Ross procedure is performed for a variety of left ventricular outflow tract diseases in children. The preoperative hemodynamic burden of pressure or volume overload and associated ventricular hypertrophy can predispose to ventricular arrhythmias. Additional procedures performed with the Ross procedure (eg, Konno) may damage the conduction system.

METHODS

Between January 1995 and February 1997, the Ross procedure was performed in 42 patients, 31 (74%) of whom had 71 prior interventions. Concomitant procedures (n = 42 in 23 patients) included 17 annular-enlarging procedures. Screening was performed for perioperative conduction and rhythm abnormalities.

RESULTS

There was one postoperative death. Perioperative ventricular tachycardia occurred in 12 patients (29%), with 2 receiving antiarrhythmic medication for ventricular tachycardia at discharge. Transient complete heart block occurred in 3 patients, all of whom had concomitant procedures performed in the subaortic area; all patients were discharged in sinus rhythm and no patient received a permanent pacemaker.

CONCLUSIONS

The Ross procedure can be performed successfully in children with complex cardiac disease with low mortality and perioperative morbidity. The incidence of perioperative ventricular tachycardia is high (29%), suggesting the need for vigilant perioperative monitoring and long-term surveillance.

Geometric mismatch of pulmonary and aortic anuli in children undergoing the Ross procedure: implications for surgical management and autograft valve function

BACKGROUND

There is often substantial mismatch between the diameters of the pulmonary and aortic anuli in young patients with systemic outflow tract disease. To implant the autologous pulmonary valve in the aortic position under such circumstances, it is necessary to adapt the geometry of the systemic outflow tract. The effects of such adaptations on autograft function in children are not well known.

METHODS

To determine factors predictive of autograft regurgitation, we analyzed 41 cases of children who have undergone the Ross procedure. The diameter of the pulmonary valve was greater (by at least 3 mm) than that of the aortic valve in 20 cases, equal (within 2 mm) in 12 cases, and less (by at least 3 mm) in nine cases, with differences ranging from +10 to -12 mm. In 12 patients with a larger pulmonary anulus, aortoventriculoplasty was used to correct the mismatch. In patients with a larger aortic anulus, the mismatch was corrected by gradual adjustment along the circumference of the autograft, rather than by tailoring of the native aortic anulus.

RESULTS

At follow-up (median 31 months), two patients had undergone reoperation on the neoaortic valve for moderate regurgitation. In the remaining 38 cases, autograft regurgitation was as follows: none or trivial in 30, mild in seven, and moderate in one. There was no correlation between regurgitation and age, geometric mismatch, or previous or concurrent procedures.

CONCLUSIONS

Subtle technical factors that may result in distortion of the valve complex are probably more important determinants of autograft regurgitation than are indication for repair, geometric mismatch, or previous or concomitant outflow tract procedures. Significant mismatch of the semilunar anuli is not a contraindication to the Ross procedure in children.

Aortic pulmonary autograft implant: medium-term follow-up with a note on a new right ventricular pulmonary artery conduit

BACKGROUND

The Ross operation has been applied to various aortic valve pathologies, particularly when somatic growth is an issue. However, associated cardiac disease and technical problems may limit its use with regard to associated procedures and issues of right ventricular outflow reconstruction.

MATERIALS AND METHODS

From December 1992 to March 1998, 24 patients underwent aortic pulmonary autograft implantation. There were 14 males and 10 females, 15+/-10 years of age (mean +/- SD) (range 1 to 50 years), weighing 42.8+/-20 kg (mean +/- SD) (range 8 to 78 kg). Aortic insufficiency was present in 15 (62.5%) patients, stenosis in 8 (33.3%) patients, and valvar stenosis associated with left ventricular outflow tract obstruction in 1 (4.1%) patient. Etiology was rheumatic in 17 patients and congenital in 7. The Ross procedure was accompanied by a partial-Konno left ventricular outflow enlargement in one patient, and mitral valve annuloplasty, mitral commissurotomy, and tricuspid valve replacement in three other patients, respectively. The right ventricular outflow was reconstructed with a valved pulmonary homograft in 14 patients and with a Shelhigh No-React porcine pulmonary conduit in 10 patients. Evaluation was done by New York Heart Association (NYHA) Class and by echocardiography at a follow-up of 22.8+/-24 months (mean +/- SD) (range 3 to 63 months).

RESULTS

There were no operative mortalities and no postoperative arrhythmias. One (4.1%) patient required intra-aortic balloon pump (IABP) support for 3 days, one (4.1%) patient died 2 years later of probable arrhythmia, and one (4.1%) patient required mechanical aortic valve replacement 2 years later for severe autograft insufficiency. Left ventricular ejection fraction was unchanged (preoperative 62.4%+/-30%, postoperative 64.2%+/-30% [mean +/- SD], [p = NS]) and no significant gradient was documented by echocardiographic Doppler in the right and left ventricular outflow tracts. The aortic insufficiency scale decreased from a mean of 3.9+/-0.2 to a mean of 1+/-0 (p < 0.01). NYHA Class decreased to I in all patients, from III (10) and II (14).

CONCLUSIONS

The pulmonary autograft in the aortic position is suitable for aortic valve replacement in pediatric and adult patients with good medium-term results and in patients with rheumatic etiology, and it provides a desirable solution in the presence of associated pathologies, such as left ventricular tract obstruction or associated multivalvular disease. The development of new means of right ventricular outflow reconstruction must parallel the progress achieved for the left side.