Raymond B. Hokken

Morphology of the pulmonary and aortic roots with regard to the pulmonary autograft procedure

Aortic root replacement with the pulmonary autograft warrants a thorough histologic comparison of the morphologic characteristics of the pulmonary and aortic roots. For this purpose nine normal heart specimens (7 neonatal and 2 adult hearts) were studied. Histologic study confirmed the collagenous anulus in both roots to be a complex circular-shaped structure, intricately interposed between the elastic lamellae of the arterial wall and the ventricular structures of the heart. In this sinus the elastic lamellae of the arterial wall continue along the luminal side with collagen being situated at the outside. At the interleaflet triangle this relation is reversed. Surprisingly, islet of elastic fibers were found in the otherwise completely collagenous interleaflet triangles. The amount of elastic lamella distal to the commissures was in both arteries higher than that in the middle of the sinuses, with a preponderance in the aorta as compared with the pulmonary trunk. The pulmonary root anulus proximally inserts into the relatively thin right ventricular myocardium, whereas the aortic root anulus inserts into the thick left ventricular myocardium and several fibrous structures. The pulmonary root is hardly supported by the right ventricular myocardium, whereas the aortic root is supported by its wedged position between the left and right atrioventricular anuli and the bulging thick left ventricular myocardium. When the pulmonary autograft is used for aortic root replacement it should be inserted as proximally as possible to get the support of the fibrous structures of the left ventricular outflow tract and the surrounding ventricular and atrial myocardium.

Does the pulmonary autograft in the aortic position in adults increase in diameter? An echocardiographic study

OBJECTIVE The objective of this study was to discern the fate of the pulmonary autograft diameter over time in adults and its relation to aortic regurgitation in the setting of aortic root replacement. METHODS From January 1989 to May 1995, 36 consecutive adult patients underwent aortic root replacement with a pulmonary autograft for aortic valve disease. The mean age of 20 male and 16 female patients was 29.1 years (range 19.3 to 52.1 years). The mean follow-up was 2.3 years (range 0.3 to 6.0 years). Two patients died in the hospital. One other patient had a second operation for stenosis at the distal suture line of the allograft in the pulmonary position. Pulmonary autograft anulus and sinus diameters were measured with epicardial echocardiography before (only anulus) and after cardiopulmonary bypass, with transthoracic echocardiography at hospital discharge, and with transesophageal echocardiography during follow-up. RESULTS The mean autograft anulus diameter did not increase immediately after cardiopulmonary bypass (mean diameter 26.2 mm before and 26.4 mm after cardiopulmonary bypass). The mean autograft sinus diameter after cardiopulmonary bypass was 36.5 mm. The mean autograft anulus diameter increased to 31.5 mm at follow-up, an increase of 5.1 mm (19%). The mean autograft sinus diameter increased to 43.9 mm at follow-up, an increase of 7.4 mm (20%). Fifty-nine percent of the anulus diameter increase and 40% of the sinus diameter increase was already reached at hospital discharge (7 to 10 days after the operation); the other part of the increase occurred during follow-up. Diameter increase was associated with neither the length of follow-up (follow-up less than 1 year compared with a longer follow-up) or severity of aortic regurgitation. CONCLUSION Pulmonary autograft anulus and sinus diameters increase the first year after aortic root replacement with a pulmonary autograft. This occurs rapidly within 10 days after the operation, with a further increase during follow-up, without causing significant aortic regurgitation at medium-term follow-up.

Allograft reconstruction of the right ventricular outflow tract.

OBJECTIVE Evaluation of allograft reconstruction of the right ventricular outflow tract (RVOT). METHODS From 1986 to April 1995, 201 allografts (146 pulmonary, 55 aortic) were implanted in 189 patients for conduit reconstruction of the RVOT in congenital heart disease or in the pulmonary autograft procedure. The mean age at allograft implantation was 16 years (range 2 weeks - 54 years). The primary diagnoses of these patients were truncus arterious (n = 19, 10%), transposition of the great arteries (TGA) with ventricular septal defect (VSD) and pulmonary atresia (PA) or stenosis (PS) (n = 14, 7%), PA with VSD (n = 26, 14%), PA or PS with intact septum (n = 7, 4%), tetralogy of Fallot (n = 44, 23%), corrected TGA with PA or PS (n = 11, 6%), tricuspid atresia (n = 9, 5%), aortic valve pathology for pulmonary autograft procedure (n = 55, 29%), and miscellaneous (n = 4, 2%). The allograft implantation was a reoperation in 54 patients (29%). RESULTS The mean follow-up was 2.5 years (range 4 weeks-9 years). Six patients died in hospital (3.2%). Patient survival at 5 years was 91% (95% CL 86-95%). Freedom from all valve-related events (2 deaths, 17 reoperations, one endocarditis), as determined during reoperation or autopsy at 5 years was 78% (95% CL 65-86%). Freedom from structural allograft failure was 83% (2 deaths, 12 reoperations, 95% CL 70-90%). Allografts implanted for congenital right heart defects failed earlier than allografts used for pulmonary autograft procedures (P = 0.05). Aortic allografts showed structural failure more often than pulmonary allografts (P = 0.05). There were more valve-related events in patients of a younger age at implantation (P = 0.02) and in those allograft valves from younger donors (P = 0.004). CONCLUSIONS Allograft RVOT reconstruction is an adequate surgical therapy. The allograft should preferably be pulmonary. A younger age at implantation is a risk factor for allograft failure. Donor age may be a thus-far underestimated risk factor for allograft degeneration.

Clinical Outcome and Left Ventricular Function After Pulmonary Autograft Implantation in Children

BACKGROUND Aortic root replacement with a pulmonary autograft is an alternative treatment for children with aortic valve or root disease, or both. METHODS Twenty-six patients (18 boys and 8 girls) with a mean age of 10.9 years (range, 0.3 to 16.9 years) underwent this procedures in a 7-year period. The mean follow-up period was 3.2 years (range, 0.2 to 7.5 years). RESULTS During follow-up 3 patients died and one autograft was replaced with a mechanical valve. The actuarial survival and actuarial event-free survival rates were 87% and 79%, respectively, at both 5 and 7 years. None of the surviving patients had complaints, and all have done well and are living normal lives. Electrocardiographic signs of myocardial ischemia and left ventricular hypertrophy were not present. Echocardiography showed autograft valve regurgitation to be absent or trivial (n = 17) or mild (n = 5). Stenosis was not present. Increasing autograft annulus diameters were noted during follow-up, but this was not related to the severity of autograft regurgitation. Left ventricular dimensions and function were within normal limits later than 1 year after the operation. Only 2 patients had a moderate pulmonary stenosis without right ventricular hypertrophy. CONCLUSIONS The surgical results, clinical outcome, valve function, and left ventricular function in our patients have been good. This procedure is recommended as a method of aortic valve replacement in children.

Repair of aortic arch interruption by direct anastomosis.

OBJECTIVE Evaluation of surgical treatment of interrupted aortic arch (IAA) by direct anastomosis. METHODS A consecutive series of 17 infants with IAA (type A in eight patients, type B in nine) were operated upon. The mean age at arch repair was 1.0 month (range 0.2-7.7), mean weight was 3.7 kg (range 2.2-6.2). All arch repairs were done by direct anastomosis. This included a persistent arterial duct in one and a subclavian turnup in another case. The aortic reconstruction included reimplantation of a lusoric artery in three patients, patch enlargement of the ascending aorta in three and of the complete arch in one patient. The arch repair was done through a lateral thoracotomy in three patients. In 14 patients the aortic repair was part of a single-stage approach through a median sternotomy using cardiopulmonary bypass and circulatory arrest. RESULTS There was no operative mortality. One patient (single-stage approach) died 2 days after operation due to respiratory problems caused by tracheobronchomalacy. One patient (lateral approach) died suddenly 3 months after aortic repair and banding. Median follow up was 4.8 years (range 0.1-12.9). In five patients restenosis of the aortic arch developed, all within 1.5 years after repair. This was not correlated with the type of interruption, weight at operation, age at operation or the surgical approach. The actuarial freedom from restenosis was 61% at 5 years with a 70% confidence limit (CL70%) of 46-75. All restenoses were balloon dilated, but two needed redo surgery, which was done by the median approach. In three patients discrete subaortic stenosis developed. This was not correlated with the type of interruption, weight at operation, age at operation or the surgical approach. The actuarial freedom from subaortic stenosis was 68% at 5 years (CL70% = 54-83). These stenoses were treated by enucleation, followed in one patient by a pulmonary autograft procedure for recurrent root stenosis after another year. At the end of follow up all patients were thriving well, lacked symptoms, were normotensive and had normal femoral artery pulsations. CONCLUSIONS IAA can be treated well with primary anastomosis. Possible restenosis of the aortic arch can adequately be treated by percutaneous balloon dilatation or redo surgery if necessary. Arch repair by median single-stage approach has our preference.