Doppler echocardiographic comparison of haemodynamic results of one- and two-stage anatomic correction of complete transposition

Cardiac “Fitness” Training: An Experimental Comparative Study of Three Methods of Pulmonary Artery Banding for Ventricular Training

BACKGROUND

When the left ventricle is unable to sustain a systemic pressure in transposition of the great arteries (TGA), left ventricular retraining is mandatory before the morphologic left ventricle under the aorta is switched. This is currently achieved by creating a ventricular overload through pulmonary artery banding, usually associated with an aortopulmonary shunt in case of a TGA with an intact ventricular septum. Our experimental study compared three different modes of increased ventricular afterload to obtain ventricular hypertrophy.

METHODS

Fifteen lambs (mean weight 48 kg) underwent pulmonary artery banding. Five animals (group I) received a classic band; 5 (group II) received a classic band which was adjusted at week 1 and 3; and 4 (group III) received a band which was tightened for 1 hour, twice a day (early morning and late afternoon). After 5 weeks, the lambs were evaluated hemodynamically before they were sacrificed and their hearts harvested for histologic examination.

RESULTS

No difference was noted in the hemodynamic data between groups 1 and II. Group III showed a greater ability to increase ventricular pressure in this model. No significant difference was noted between the three groups in terms of macroscopic alterations, but all animals demonstrated an increase in right ventricular wall thickness compared with control animals. Several fibrosis areas were evident in group I and II but none in group III.

CONCLUSIONS

Intermittent pulmonary artery banding is able to induce hemodynamically sufficient ventricular hypertrophy without fibrosis.

Prevalence and predictors of neoaortic regurgitation after arterial switch operation for transposition of the great arteries

BACKGROUND

The fate of the native pulmonary valve after arterial switch operation is still unknown and may become a cause for a secondary aortic valve operation during adult life. We evaluated the prevalence and predictive factors associated with neoaortic valvular regurgitation by a retrospective study of children who underwent arterial switch operation for transposition of the great arteries.

METHODS

The onset of neoaortic valvular regurgitation was correlated with demographic data, cardiac anatomy, surgical technique, and postoperative ventricular function. The size of the neoaortic root and ascending aorta was measured in a selected subset of patients.

RESULTS

Among 253 survivors, 173 were eligible for the study. After a median follow-up time of 8.2 years, 61 patients showed echocardiographic or angiographic evidence of valvular incompetence, which was progressive in 14 cases; this led to surgical intervention in 2 patients, and there was 1 operative death. At multivariate analysis, the onset of valvular regurgitation was correlated with the trap-door technique for coronary reimplantation (P <.01). A smooth transition from the aortic sinus to the ascending aorta, with loss of the normal sinotubular junction geometry, may be associated with valvular incompetence.

CONCLUSIONS

After arterial switch operation, there is an increasing frequency of neoaortic regurgitation, which may lead to significant valvular dysfunction later in life. The trap-door type of coronary reimplantation is associated with an increased risk for valvular dysfunction, possibly because of a distortion of the sinotubular junction geometry. For this reason, we recommend the punch technique for repair in all but the most complicated coronary pattern.

Two-stage arterial switch operation: is late ever too late?

Results of the two-stage arterial switch operation in 49 patients with transposition of the great arteries, performed between January 1995 and September 2000, were reviewed retrospectively. Twenty-one patients had a ventricular septal defect. Anatomical correction was carried out 21.89 +/- 9.86 months after pulmonary artery banding, with or without a modified Blalock-Taussig shunt. Hospital mortality was 8% (4 patients). During follow-up of 30.12 +/- 14.38 months, there was 1 late death and 1 patient required reoperation for pseudoaneurysm of the ascending aorta. Actuarial survival and freedom from reoperation at 5 years were 90% and 97%, respectively. Late anatomic correction (> 6 months) after the preliminary procedure can be performed with an acceptable mortality and morbidity, but undue delay may lead to left ventricular dysfunction, arrhythmias, and new aortic valve regurgitation or subaortic stenosis.

Experience of the Arterial Switch Operation beyond Infancy

The arterial switch operation in the neonatal period is the treatment of choice for complete transposition of the great arteries. Since 1995, we have performed the arterial switch operation with or without closure of a ventricular septal defect in 7 patients who presented beyond infancy. Their ages ranged from 21 to 60 months (mean age 40 months). Four patients had ventricular septal defects and 3 had an intact ventricular septum. Six underwent pulmonary artery banding before the operation and one had a subpulmonic membrane that acted as a pulmonary artery band. All patients survived the operation; two developed mild to moderate aortic regurgitation that decreased over time. Based on our experience and good results we conclude that the arterial switch operation is still the procedure of choice for such patients who present beyond the period of infancy.

Serial echocardiography for decision making in rapid two-stage arterial switch operation

BACKGROUND

Rapid two-stage arterial switch operation is advocated in infants with simple transposition presenting late. Accurate assessment of left ventricular preparation is crucial to successful outcome. The role of echocardiography alone in surgical decision making remains unclear.

METHODS

Seventeen patients with simple transposition (mean age, 4 months) underwent pulmonary artery banding and modified Blalock-Taussig shunt (first stage) to prepare the left ventricle for the arterial switch operation (second stage). Serial echocardiography was performed in the interval phase to assess left ventricular growth. Sixteen patients underwent arterial switch operation after a mean interval of 10.4 +/- 4 days, with 14 successful conversions. There was one mortality (5.9%) and two conversions to a Senning repair.

RESULTS

In all patients a mean increase in left ventricular mass (40.8 +/- 17.8 g/m2 to 81.4 +/- 25.4 g/m2) and posterior wall thickness (3.37 +/- 0.47 mm to 4.63 +/- 0.58 mm) was recorded. Left ventricular end-diastolic internal diameter increased in all except the two switch failures. In all the successful cases the left ventricle had assumed a circular shape on cross-section with the interventricular septum contracting in synergy with the left ventricular mass. In the two failures, however, the interventricular septum had remained flat.

CONCLUSIONS

Echocardiography can be used reliably in surgical decision making in rapid two-stage arterial switch operation. Increase in left ventricular mass, left ventricular posterior wall thickness, and left ventricular end-diastolic internal diameter toward normal combined with an acquisition of circular left ventricular configuration with the interventricular septum contracting in synergy with the left ventricular mass appear to best predict successful outcome.

Induction of right ventricular hypertrophy with obstructing balloon catheter. Nonsurgical ventricular preparation for the arterial switch operation in simple transposition

BACKGROUND

Recently, a successful result with a rapid two-stage arterial switch operation (ASO) was reported for patients with transposition of the great arteries (TGA) with low left ventricular pressure. In this procedure, the interval between pulmonary arterial banding and ASO was approximately 1 week. This successful result indicates the possibility of a nonsurgical ventricular preparation procedure using an obstructing balloon catheter prior to ASO.

METHODS AND RESULTS

A 5F atrioseptostomy catheter was inserted directly into the main pulmonary artery in six lambs aged 20 to 38 days. After the chest was closed, the balloon was inflated twice a day for a period of 2 to 2.5 hours. This procedure was performed for 4 consecutive days. After the final inflation, the ratio of right ventricular weight to total ventricular weight was compared with that in an age-matched control group. After the final inflation, the peak systolic right ventricular pressure and the percentage of peak systolic right ventricular to peak systolic aortic pressure rose to 85.6 +/- 4.7 mm Hg (mean +/- 1 SD) and 79.6 +/- 8.6%, respectively. The percentages of the right ventricular weight to the total ventricular weight were significantly higher after the balloon inflation than those in the control group in terms of wet heart weight (29.5 +/- 1.2% versus 23.0 +/- 1.0%; P < .0001) and dry heart weight (27.0 +/- 2.0% versus 21.0 +/- 1.1%; P < .0001).

CONCLUSIONS

The myocardial mass in the right ventricle increased after 4 days of intermittently applied pressure overload. Nonsurgical preparation of the ventricle for ASO in TGA is feasible.

Growth of the aortic anastomosis, annulus, and root after the arterial switch procedure performed in infancy

BACKGROUND

We investigated the size and growth potential of the neoaortic root and aortic anastomosis after the arterial switch operation (ASO) for D-transposition of the great arteries (D-TGA) performed in infants. Circumferential suture lines connecting the great arteries and extensive surgery on the arterial roots to transplant the coronary arteries are essential parts of the ASO. However, little is known about the growth of the aortic anastomosis, the neoaortic root, and the neoaortic annulus after the ASO performed in infancy.

METHODS AND RESULTS

Serial echocardiograms on 50 patients with D-TGA who underwent ASO in infancy at our institution were reviewed, and the size of the aortic anastomosis, the neoaortic root, and the neoaortic annulus were compared with similar structures in a group of 312 control subjects. Before surgery, the native pulmonary root (future neoaortic root) was 1.59 SD larger (P < .001) and the native pulmonary annulus (future neoaortic annulus) was 1.4 SD larger (P < .001) in infants with D-TGA than the aortic root and annulus of control patients. At a mean of 22 months (12 months to 6 1/2 years) after surgery, the diameter of the aorta at the anastomosis was 0.45 SD smaller than the ascending aorta of control subjects (P < .001). The neoaortic root was 2.9 SD larger (P < .001) and the neoaortic annulus was 1.6 SD larger (P < .001) than the comparable structures in the control population. Most important, growth of the aortic anastomosis was commensurate with somatic growth, but the dilation of the neoaortic root appeared to be progressive over time. The neoaortic root was significantly more dilated in patients with a history of pulmonary artery banding (P < .001) and in patients with neoaortic regurgitation (P < .001). The presence of a ventricular septal defect was not significantly related to postoperative neoaortic root size.

CONCLUSIONS

This study underlies the importance of continued acquisition and examination of the data regarding the long-term outcome of the arterial switch operation performed in infancy.

Intermediate-term clinical and hemodynamic results of the neonatal arterial switch operation for complete transposition of the great arteries

We prospectively evaluated 49 consecutive hospital survivors of the arterial switch operation for complete transposition and intact ventricular septum by clinical examination, echocardiography, cardiac catheterization, 12-lead and 24-h Holter ECG. The mean length of follow-up was 40 +/- 18 months. Forty-six children are clinically asymptomatic without medication, 2 died due to coronary related left ventricular dysfunction 3 and 12 months after surgery, and 1 required reoperation because of severe bilateral pulmonary branch stenoses. Except for this case, cardiac catheterization (n = 23) revealed a mean gradient of only 17 +/- 8 mmHg between the right ventricle and distal pulmonary arteries. Left ventricular end-diastolic volume was within normal limits except for 2 cases with volumes slightly below normal, the mean ejection fraction was 78 +/- 5%, and end-diastolic and end-systolic ventricular shapes were normal. The mean cardiac index was 4.14 +/- 0.69 l/min/m2. Left ventricular end-systolic wall stress to velocity of fiber shortening relation was normal in all cases examined (n = 15), indicating normal myocardial contractility. Significant neoaortic valve insufficiency was never observed despite considerably enlarged aortic roots. Twenty-four-hour Holter ECG records (n = 46) provided no evidence of serious atrial arrhythmias, especially sinus node dysfunction. These encouraging intermediate-term results make the arterial switch operation the treatment of choice at present, for neonates with simple transposition.

Results of the arterial switch operation for transposition of the great arteries with ventricular septal defect. Surgical considerations and midterm follow-up data

Between January 1983 and December 1987, 62 patients underwent an arterial switch operation for transposition of the great arteries with ventricular septal defect or double outlet right or left ventricle. There were three hospital deaths (4.8%), and no deaths occurred in neonates (less than 1 month of age, n = 18). There were three late deaths, one due to coronary obstruction and two due to pulmonary vascular obstructive disease. One child has been lost to follow-up. We have prospectively evaluated the remaining 55 survivors by clinical evaluation, echocardiography, cardiac catheterization, ambulatory electrocardiographic monitoring, and limited electrophysiologic studies. The mean length of follow-up has been 27 +/- 16 months since surgery. One child has required reoperation for a residual ventricular septal defect; no child has undergone reoperation for supravalvar pulmonary or aortic stenosis. Aortic regurgitation was identified in 12 children (22%), which was mild in 11 and moderate in one. One child has asymptomatic occlusion of the left main coronary artery, one child has a tiny right coronary artery-to-pulmonary artery fistula, and one child has abnormal left ventricular wall motion according to follow-up angiography. No other abnormalities of systemic (left) ventricular function have been identified at late follow-up. In addition to the two late deaths due to pulmonary vascular obstructive disease, three children, all of whom were repaired at more than 6 months of age, have elevated pulmonary vascular resistance. Notable postoperative arrhythmias include complete heart block in four patients and nonsustained supraventricular or ventricular tachycardia early after surgery in eight patients (all resolved without medication at later follow-up). Only two patients have evidence of sinus node dysfunction and have not required treatment. The low hospital mortality and encouraging early follow-up data represent a significant improvement over atrial level repairs, supporting the arterial switch operation as the procedure of choice for children who have transposition of the great arteries with ventricular septal defect or double outlet ventricle. Because of the potential for the development of early pulmonary vascular obstructive disease in these patients, repair is recommended within the first 2 months of life.

A quantitative evaluation of aortic regurgitation after anatomic correction of transposition of the great arteries

Twenty patients who had undergone anatomic correction of transposition of the great arteries were assessed by Doppler echocardiography or cardiac catheterization, or both, to identify the presence of aortic regurgitation. The severity of aortic regurgitation was evaluated by radionuclide angiographic measurement of the stroke volume index a mean of 47.1 months postoperatively. The stroke volume index was defined as the ratio of the stroke counts between the left and right ventricles. A value greater than 1.8 was considered to indicate significant left ventricular volume overload. Eight patients (40%) were shown to have various degrees of aortic regurgitation by Doppler echocardiography or cardiac catheterization, or both. The mean (+/- SD) stroke volume index was 1.03 +/- 0.15 in these patients and 1.01 +/- 0.21 in the 12 patients without aortic regurgitation (p = NS). The stroke volume index was not above the normal range in any patient, indicating that the degree of aortic regurgitation present was trivial. This medium-term study indicates that trivial or mild aortic regurgitation is a frequent finding after anatomic correction of transposition of the great arteries. However, it rarely results in an audible cardiac murmur or significant left ventricular volume overload. Long-term evaluation is required to determine its importance.

Neonatal anatomical correction of transposition of the great arteries: non-invasive assessment of haemodynamic function up to four years after operation

Intracardiac and great artery blood flow velocities were recorded by pulsed and continuous wave Doppler ultrasound in 18 children aged between eight months and four years (mean 25 months) who had undergone anatomical correction of transposition of the great arteries in the first month of life. Postoperative peak flow velocities across the mitral valve and in the ascending aorta were not significantly different from those in an age matched control population, but tricuspid flow velocities were higher than normal. Aortic regurgitation was detected in only one of the eighteen patients, a markedly lower frequency than that reported after two stage anatomical correction. Peak velocities in the pulmonary artery were higher than normal, and in most cases there was some degree of stenosis of the pulmonary artery at the site of anastomosis.