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Biomedical subjects

R B Mee

Publications and source records attributed to R B Mee.

At least 73 records · Page 4Linked to original sources
PubMed1991

Extracardiac valved conduits in the pulmonary circuit.

Extracardiac valved conduits represent one of the weakest facets of reconstructive surgery for congenital heart disease in that they invariably need to be replaced because of growth of the patient or because of valve or conduit failure. Between 1979 and 1989, 141 patients had 169 valved conduits placed between the heart and the pulmonary artery circuit. There were 81 male and 60 female patients, aged 2 days to 35 years (mean age, 5.9 years), with 46 patients less than 1 year of age. We performed primary repair in 117 patients; in this group, there have been 28 conduit replacements in 27 patients. In 17 patients initial repair with a conduit was performed elsewhere and we replaced these conduits in 15 and removed them in 2. A further group of 9 patients were seen after repair of tetralogy of Fallot or double-outlet right ventricle, with severe pulmonary incompetence or right ventricular outflow tract aneurysm. All had valved conduits inserted as secondary procedures. The types of valved conduits used were xenograft (n = 126) and homograft (n = 43). There were six hospital deaths (3.6%; 70% confidence limits [CL], 2% to 6%) and seven late deaths (4.1%; CL, 2.5% to 6.5%) in a total of 169 conduit insertions. Forty-five conduits have been removed and 43 reinserted without early or late mortality (0%; CL, 0% to 4%). Actuarial survival after conduit insertion was 87% at 5 years (CL, 80% to 92%), including operative mortality. Actuarial freedom from conduit replacement was 37% at 5 years (CL, 20% to 56%). Conduit insertion in infants and small children ensures subsequent replacement, but this can be done at low risk.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Discordant atrioventricular connexion with concordant ventriculo-arterial connexion (so-called "isolated ventricular inversion") with usual atrial arrangement (situs solitus).

The combination of a discordant atrioventricular connexion with a concordant ventriculo-arterial connexion (so-called "isolated ventricular inversion") is an extremely rare entity described, to the best of our knowledge, on only 15 occasions in patients with usual atrial arrangement. Initial diagnosis at cross-sectional echocardiography has only been reported three times, but the combination has been diagnosed in life on seven occasions, with successful Mustard or Senning operations having been performed in six of these patients. We report a neonate referred with an initial diagnosis of complete transposition, who was correctly diagnosed at cross-sectional echocardiography, and had closure of an associated ventricular septal defect with a Senning procedure in the neonatal period.

Crisscross Heart↗
PubMed1991

Severe subaortic stenosis in interrupted aortic arch in infancy and childhood.

Thirteen out of a total 50 infants with interrupted aortic arch (IAA) seen between 1979-1988 had or developed severe subaortic stenosis (SAS). One had type A interruption and 12 type B. All had a large ventricular septal defect (VSD). The infundibular septum was displaced posteriorly in eight infants, severely narrowing the left ventricular outflow tract (LVOT). Three had fibromuscular narrowing of the LVOT, one each a subaortic muscle bar and membrane. The aortic root and subaortic area were small and measured between 3-8 mm. An anomalous right subclavian artery was noted in eight of the 12 type B IAA, the anomalous vessel arising from the descending aorta in seven. Thirteen infants with IAA and SAS were submitted to surgery, 12 having their subaortic area resected with three perioperative deaths early in the series and three late deaths where active treatment was ceased, including one infant with renal dysplasia who had had a successful establishment of arch continuity and pulmonary artery banding. Of the seven survivors, six have residual Doppler gradients of between 20-50 mmHg, two requiring a second resection and one a third resection. Alternate management programs are suggested based on anatomical evaluation and echocardiography. Any newborn presenting with IAA requires careful evaluation of the subaortic area, best seen on cross-sectional echocardiography. The improved surgical survival in infants following complete repair of IAA has led this important associated anomaly of subaortic stenosis to assume greater importance as a cause of mortality and long-term morbidity.

Anastomosis, Surgical↗
PubMed1991

Centrifugal pump left heart assist in pediatric cardiac operations. Indication, technique, and results.

Twelve children aged 6 days to 12 years had left or common atrial to aortic extracorporeal support with a centrifugal pump after cardiac operations. Left ventricular assist time ranged from 38 to 190 hours. Ten patients were successfully weaned from left ventricular assist device support; four hospital deaths occurred afterward. All six survivors were discharged from the hospital with improved left ventricular function. Although the follow-up time is short and the experience limited, we consider the centrifugal pump type of left ventricular assist device to be a potentially lifesaving treatment modality for selected pediatric patients having cardiac operations.

Cardiac Output, Low↗
PubMed1990

Critical aortic stenosis in the first month of life: surgical results in 26 infants.

Between 1980 and 1989, 26 infants aged less than 1 month underwent open aortic valvotomy for critical aortic stenosis. All had congestive heart failure requiring inotropic agents (58%), ventilation (42%), and/or prostaglandin E1 (35%) preoperatively. Nine patients with isolated aortic stenosis had an operative mortality of 0%, whereas 17 patients with other anatomical lesions had a 47% mortality (p less than 0.01). Univariate analysis failed to identify additional risk factors other than year of operation (p less than 0.05). There were four late deaths, three probably related to arrhythmia (actuarial survival at 113 months = 0.53). Two patients have required late reoperation; neither required valve replacement.

Actuarial Analysis↗
PubMed1990

Isolated myocardial perfusion during arch repair.

Repair of coarctation of the aorta with severe hypoplasia of the aortic arch or interrupted aortic arch was performed in 5 patients using a modification of the usual technique that consisted of isolated myocardial perfusion during arch repair. The aortic cross-clamp was placed on the ascending aorta distal to the aortic cannula. Cardiopulmonary bypass flow was reduced to about 10% of full flow, achieving a line pressure of 35 to 45 mm Hg to keep the heart perfused and beating during arch repair. Once the aortic arch was repaired, total body perfusion was continued as usual and intracardiac repair was performed. Isolated myocardial perfusion for aortic arch reconstruction reduces myocardial ischemic time.

Aorta↗
PubMed1990

Repair of truncus arteriosus and interrupted aortic arch.

A total of seven patients with truncus arteriosus and interrupted aortic arch (IAA) comprises our surgical experience in this condition. All underwent primary complete repair via median sternotomy between June 1985 and December 1989. Median age at repair was 8 days and median weight, 3.2 kg. Anatomy of these seven patients was truncus arteriosus type "1 1/2" in five patients and type II in two patients, IAA type B in six patients and type A in one patient. Aortic arch was reconstructed by direct anastomosis of ascending aorta and descending aorta. Right ventricle to pulmonary artery continuity was established with a porcine valved conduit in four patients, aortic homograft in two, and aortic homograft monocusp patch in one. Three patients have required five reoperations (three in one patient). One reoperation was due to compression of the left main bronchus from the reconstructed aorta, one was due to obstruction of the aorta at the site of IAA repair, and one was due to compression of the left main bronchus, right pulmonary artery, and residual stenosis across the hypoplastic ascending aorta. There were no early or late deaths and all seven survivors are currently well with a mean follow-up of 29 months from initial repair.

Anastomosis, Surgical↗
PubMed1990

Two-patch repair of complete atrioventricular septal defect in the first year of life. Results and sequential assessment of atrioventricular valve function.

Before January 1987, 62 infants underwent two-patch repair of complete (51) or intermediate (11) atrioventricular septal defect at the Royal Children's Hospital, Melbourne. Median age at repair was 4.3 months and median weight was 4.4 kg. Early deaths (3%) were confined to two infants with preoperative respiratory tract infections; a further two patients died during follow-up (late mortality rate 3%). Reoperation for severe postoperative mitral regurgitation was necessary in 10 infants (16%), two of whom subsequently required mitral valve replacement with a prosthesis. Preoperative atrioventricular valve regurgitation was assessed retrospectively in 49 patients from angiography or Doppler echocardiography and was found to be absent or mild in 33 (68%), moderate in 9 (18%), and severe in 7 (14%). At the time of latest review (at a mean of 2.4 years after repair), judged from a combination of clinical and echocardiographic criteria, mitral regurgitation was absent or mild in 49 (84%) of the 58 survivors; none of them had symptomatic regurgitation or were requiring continuing medical treatment. Analysis of sequential atrioventricular valve function in 46 of the 49 patients in whom objective preoperative data were available showed no relationship between the degree of preoperative and postoperative atrioventricular valve regurgitation. Infants without Down's syndrome, however, had a significantly higher reoperation rate for severe postoperative mitral valve regurgitation (50%) than those with Down's syndrome (10%) (p = 0.007). Complete atrioventricular septal defect can be repaired in early infancy with a low mortality rate and good intermediate term results.

Female↗
PubMed1989

Use of azygos vein as interposition graft for surgical unifocalization of pulmonary blood supply.

Hemodynamic repair in patients with pulmonary atresia, ventricular septal defect, hypoplastic pulmonary arteries with arborization defects, and major aortopulmonary collaterals necessitates prior unifocalization of pulmonary artery blood supply. When direct anastomosis between these collateral vessels and the central pulmonary arteries is not technically feasible, an interposition graft is required. Dacron, polytetrafluoroethylene, and pericardium have been used for this purpose. We describe our experience with the use of azygos vein as an interposition graft in 3 patients who underwent unifocalization of the pulmonary blood supply to the right lung. Our experience suggests that the azygos vein is a useful graft for use in this specific form of unifocalization procedure.

Aorta, Thoracic↗
PubMed1989

Left heart assist for ischemic postoperative ventricular dysfunction in an infant with anomalous left coronary artery.

A baby weighing 6.2 kg with anomalous origin of the left coronary artery from the pulmonary artery developed profound left ventricular failure during surgical repair. He was supported for 41 hours with centrifugal pump left heart assist. Recovery following cessation of ventricular assist was uneventful and ventricular function was improved compared to preoperative status.

Cardiac Output, Low↗
PubMed1989

Total anomalous pulmonary venous drainage.

Forty-four patients with total anomalous pulmonary venous drainage underwent repair between 1979 and 1987. The anomalous drainage was supracardiac in 16, cardiac in 12, and infracardiac in 16. Median age at repair was 15 days and median weight, 3.3 kg. In 22 patients (50%) the venous drainage was obstructed. Emergency operation was necessary in 12 patients, and the condition of seven additional patients deteriorated while they were awaiting semiurgent operation. There was one hospital death (mortality rate 2.3%), occurring in a 2-week-old premature neonate with infracardiac drainage. In 17 of 44 patients, mean pulmonary artery pressure equaled or exceeded systemic arterial pressure immediately after repair. Four patients have required reoperation and two of these have died as a result of peripheral extension of pulmonary vein sclerosis. In the review period of from 1 month to 7 years, all survivors are well and receiving no medication.

Angiography↗
PubMed1988

Effects of vasodilators on rates of change of nasopharyngeal temperature and systemic vascular resistance during cardiopulmonary bypass in anaesthetized dogs.

The effects of various vasodilating agents on the rates of change of nasopharyngeal temperature and total systemic vascular resistance of anaesthetized dogs during cardiopulmonary bypass were studied. Intravenous administration of nitroglycerine (14 micrograms/kg per min, infused at 35 degrees C and 36 degrees C), sodium nitroprusside (5 micrograms/kg per min, infused at 36 degrees C) and phenoxybenzamine (1 mg/kg bolus, given at 32 degrees C and 36 degrees C) did not have any effect on the total cooling time or the rate of cooling from 36 degrees C to 18 degrees C. However, in dogs treated with phenoxybenzamine the time taken to rewarm to 36 degrees C was significantly shorter than those observed in the control, nitroglycerine or sodium nitroprusside treated animals. This difference in rewarming time was mainly due to the more even rate of rewarming induced by phenoxybenzamine. Moreover, a significantly greater reduction in systemic vascular resistance was observed in phenoxybenzamine treated animals than in the other treatment groups.

Anesthesia↗
PubMed1988

Early results for anatomic correction of transposition of the great arteries and for double-outlet right ventricle with subpulmonary ventricular septal defect.

Fifty patients, 21 with transposition of the great arteries plus ventricular septal defect, four with double-outlet right ventricle plus ventricular septal defect, and 25 with transposition of the great arteries plus intact ventricular septum, have undergone anatomic correction. There were four hospital deaths, all in the patients with ventricular septal defects (overall mortality rate 8%). The Lecompte maneuver was used in all patients, and in the last 25 patients the coronary arteries were transposed to medially hinged trapdoor flaps created in the neoaorta. In 10 patients (20%) intraoperative adjustments were necessary to the great vessels and coronary arteries to achieve unobstructed coronary artery flow. There have been no late deaths. Postoperative cardiac catheterization in 19 patients has revealed stenosis on the new main pulmonary artery suture line to be the main early problem. Anatomic correction of transposition (with or without ventricular septal defect) and double-outlet right ventricle septal defect would seem to be a good operative alternative to the Mustard or Senning operation, with the advantage of incorporating the left ventricle into the systemic circulation.

Aorta↗
PubMed1987

Cerebellar infarction secondary to subclavian aortoplasty repair for coarctation of the aorta.

A five-year-old boy developed a left cerebellar infarction following repair of coarctation of the aorta by subclavian aortoplasty. At operation a large left vertebral artery had been ligated. If a large vertebral artery is encountered at repair of coarctation of the aorta then consideration should be given to a method of repair which does not sacrifice this vessel.

Aortic Coarctation↗
PubMed1987

Surgical excision of primary cardiac tumours in infancy.

Six cases of primary cardiac tumour have been operated upon in a 7 year period from 1 June 1979 until 1 June 1986. All patients were under 6 months of age at the time of operation and two of the patients were in their first week of life. The principal indication for surgery was obstruction mainly at the right or left ventricular outflow tract level. More recently echo evaluation alone has been adequate to define the problem prior to surgery. Surgical excision has been performed without mortality or significant complications. In most cases resection has been complete, although in one case residual tumour has been left because of attachment of the tumour to vital structures. Follow-up of this case has not resulted in further surgery being required because of regrowth of the tumour. In one case, with co-existent congenital heart disease, the tumour was brought to notice after palliative systemic to pulmonary artery shunt had been performed. From the cardiac view point gratifying results have been obtained both in the short and long term following surgical resection. However, for patients with rhabdomyoma, later development of symptomatic tuberosclerosis should be anticipated in 50% of cases.

Dysgerminoma↗