PubMed Health⌕ Search

Biomedical subjects

D I Hamilton

Publications and source records attributed to D I Hamilton.

At least 37 records · Page 2Linked to original sources
PubMed1981

Development of a twin-flap, porous ceramic mitral valve prosthesis.

The pressure drop in most existing cardiac valve prostheses is at least ten times greater than for healthy valves. Steady flow testing indicates that the causes are (i) poor orifice diameter/sewing ring diameter ratio; (ii) occluding mechanism causes obstruction in the region of highest blood velocity. A new mitral prosthesis was constructed to overcome these deficiencies. The significant features are (a) tubular construction to maximize flow area; (b) twin flaps with hinges well above the outlet to minimize obstruction; (c) divergent nozzle to aid pressure recovery. Prostheses were manufactured from porous alumina, promoting firmly anchored, thin tissue growth to reduce haemolysis and thromboembolism. Preliminary trials in mini-pigs show good valve function. The ceramic behaves especially well. Future models will use ceramic flaps to replace the delrin flaps used ast present, which encourage fibrin deposits.

Animals↗
PubMed1981

Eight years' experience with intracardiac repair of tetralogy of Fallot. Early and late results in 175 consecutive patients.

The early and late results of intracardiac repair of 175 cases of tetralogy of Fallot during the period 1969 to 76 are reviewed. Overall hospital mortality was 8%, with a 5% mortality in patients over 2 years of age. Late mortality was 1%. Both early and late mortality and morbidity were related to the right ventricular to left ventricular peak systolic pressure ratio measured at the end of the operation. During the eight year period, a fall in mortality from 37 to 15% was recorded in patients less than 2 years of age. As a result of the experience gained during this period, we have now adopted a more active policy towards reconstruction of the right ventricular outflow tract while remaining aware of the potential problems of pulmonary regurgitation.

Adolescent↗
PubMed1981

Surgical experience with persistent truncus arteriosus in symptomatic infants under 1 year of age. Report of 13 consecutive cases.

Between January 1974 and November 1980, 13 symptomatic infants under 1 year of age with persistent truncus arteriosus type I or II underwent surgery. Pulmonary artery banding was performed in 10 cases, with five deaths. Among the survivors, one developed severe pulmonary vascular disease and only two underwent late intracardiac repair. Primary total correction was performed in three infants and all are well, though one required conduit replacement five and a half years after the initial procedure. Recently, antibiotic sterilised homograft conduits, rather than heterografts, have been preferred as extracardiac conduits in infancy. Early intracardiac repair followed, if necessary, by later conduit replacement appears to have significant advantages over "conventional" pulmonary artery banding and late total correction. Concern remains on the treatment of choice in infants under 3 months of age.

Age Factors↗
PubMed1981

Aortoplasty with the left subclavian flap in older children.

Ten patients between 8 months and 9 years of age (average 4.3 years) underwent surgical relief of coarctation of the aorta by the technique of left subclavian flap aortoplasty. Before operation, nine patients had systolic hypertension in the upper extremity (average 145 mm Hg) and all had a significant pressure gradient across the coarctated aortic segment (average 45 mm Hg). The hospital and late mortality were zero. The follow-up over 7 years has shown complete relief of the coarctation and no ischemic impairment or functional limitation of the left upper extremity. The blood pressure returned to normal in all patients. Hemodynamic and angiographic studies, performed in one case, demonstrated adequate growth of the repaired segment and absence of a pressure gradient across the previously narrowed area. The time interval between the peak of the femoral pulse and the dicrotic notch of the carotid pulse, recorded postoperatively, was normal. We consider the left subclavian flap technique to be the operation of choice in infancy and also in older children, whenever the anatomic configuration of the coarctation suggests that subsequent growth would be severely restricted if other techniques were used.

Aorta, Thoracic↗
PubMed1981

Interposition of a modified aortic homograft conduit as main pulmonary trunk in anatomic correction of transposition of the great arteries. Report of two cases and technical considerations.

Anatomic correction of transposition of the great arteries and ventricular septal defect has been performed successfully in two patients. The technique employed differed in several aspects from the so-called Jatene procedure: (1) Both great arteries were transected at low level; (2) the switch of the coronary arteries was carried out after transection of both great arteries; (3) a modified aortic homograft conduit was used to bridge the gap between the proximal aortic root and the distal main pulmonary artery; (4) the "new" main pulmonary arterial trunk was positioned on the right side of the ascending aorta; and (5) the ascending aorta was enlarged in order to match the dilated proximal pulmonary stump. The advantages of these modifications over other techniques reported in the literature are discussed.

Aorta↗
PubMed1981

Appraisal of the Mustard procedure for the physiological correction of "simple" transposition of the great arteries. Eighty consecutive cases, 1970-1980.

Eighty successive patients underwent the Mustard operation for "simple" transposition of the great arteries (TGA) between January, 1970, and January, 1980. Ages ranged from 42 days to 12.4 years (mean 14.7 months). Balloon atrial septostomy (BAS) with balloon volumes of more than 2.5 ml produced significant increases of arterial oxygen saturation, although the initial benefit of BAS was greater than that found at follow-up catheterization. In these patients the left ventricular (LV) pressure tended to decrease during the first months of life, but this drop was less marked at the end of the first year. Deep hypothermia and cardiocirculatory arrest were employed in all cases. Several modifications were adapted to the original surgical technique in order to reduce last sequelae. There were two early and three late deaths. At follow-up (mean 4.5 years) 74% of patients were symptom free. Sinoatrial and atrioventricular (AV) conduction disturbances were present in five and six patients, respectively. Caval or pulmonary venous obstruction occurred in 13 patients, seven of whom required reoperation. Isolated tricuspid valve incompetence was present in one patient only, but in four it was associated with other defects. Primary right ventricular (RV) failure occurred in one patient. These findings, in relation to mortality, complications, and the excellent clinical results in the majority of survivors, compare favorably with results published for patients with "simple" TGA who have been subjected to other types of physiological or anatomic correction. At the present time, there seems to be no good reason to alter our surgical policy in this group of patients.

Blood Pressure↗
PubMed1980

Indirect arterial pulse tracings in children with coarctation of the aorta before and after operation.

Eleven children with coarctation of the aorta were investigated before and after surgical treatment, using simultaneous indirect carotid and femoral pulse wave tracing. The timing of the onset of the femoral pulse in the children with coarctation, both before and after operation, did not differ significantly from normal. However, the time interval between the peak of the femoral pulse and the dicrotic notch of the carotid pulse was significantly shorter than normal in the children with coarctation before operation. After operation, the peak femoral to carotid dicrotic notch time interval was restored to normal. It is suggested that this simple non-invasive test might be of value in the long-term follow-up of patients after operation for coarctation of the aorta, particularly in those undergoing operation early in childhood, to detect residual or recurrent coarctation.

Adolescent↗
PubMed1979

Traumatic intercostal hernia due to a nonpenetrating injury in a child.

Herniation of the lung is a recognized, though rare, complication of thoracotomy and penetrating chest injury. Closed chest injury is usually associated with rib fractures, laceration of the lung, and rupture of the diaphragm, bronchus, and aorta. It is unusual for the intercostal muscles to be ruptured in a closed chest injury. In this case, herniation of the lung may result.

Child↗
PubMed1979

An operation for anomalous origin of left coronary artery.

Successful surgical correction for anomalous origin of the left coronary artery from the pulmonary artery in a 4-year-old child is reported. An aortopulmonary fistula was created and a pericardial baffle was inserted within the pulmonary artery to connect the fistula to the ostium of the left coronary artery. The clinical, haemodynamic, and angiographic features of the anomaly are presented. The child's progress is satisfactory 17 months after the operation.

Child, Preschool↗
PubMed1979

Open heart surgery in first year of life using profound hypothermia (core cooling) and circulatory arrest. Experience with 134 consecutive cases.

Between April 1970 and December 1977, 134 infants aged 2 days to 12 months underwent open heart surgery using profound hypothermia and total circulatory arrest. The technique of bypass (core) cooling is described. Results are reviewed for 4 principal diagnoses: 'simple' transposition of the great vessels, total anomalous pulmonary venous connection, ventricular septal defect, and Fallot's tetralogy. A mortality of 44 per cent in 32 cases during the first 3-year period has been reduced to 22 per cent in 102 cases during the subsequent 5 years. The overall mortality for the entire period was 28 per cent. The policy for the management of each diagnostic group is outlined.

Cardiac Surgical Procedures↗
PubMed1979

Reconstructing of the right ventricular outflow tract using an inlayed aortic root homograft.

Our experience with the use of a fresh antibiotic sterilized aortic root homograft inlayed into the right ventricular outflow tract is described. With this technique, compression of the graft between the sternum and heart has been avoided and residual right ventricle to distal pulmonary artery pressure gradients have been small. The functional status of the survivors is good over a follow-up period of up to 3 yr. The advantages of this approach compared with a conventionally placed heterograft conduit or an outflow tract gusset are discussed.

Adolescent↗
PubMed1978

Total anomalous pulmonary venous connection (surgical technique, early and late results).

Between March 1970 and October 1977, 36 patients underwent correction of total anomalous pulmonary venous connection. The ages ranged from 5 days to 16 years; 27 (75%) were under 1 year and 19 were under 3 months of age at the time of surgery. The overall mortality was 33%. Supracardiac connection was the commonest type and was associated with the lowest hospital mortality (30%). The highest mortality occurred in the mixed and infracardiac types and was related in part to the presence of associated intracardiac anomalies. The use of hypothermia and circulatory arrest in infancy has resulted in a considerably lower hospital mortality compared with cases operated on under conventional cardiopulmonary bypass. The mortality in 23 infants (under 1 year of age) was 26% using circulatory arrest and was lowest when correction was performed within the first three months of life (18%). All four infants operated on with standard cardiopulmonary bypass died, whereas this technique was found to be safe in older children. The surgical technique using a left anterolateral thoractomy with a trans-sternal extension is described. This technique gives an excellent exposure for fashioning a long anastomosis and has been associated with a low incidence of postoperative pulmonary complications. There have been no late deaths and all survivors, who are in excellent condition up to seven years after correction, have a normal exercise tolerance.

Adolescent↗
PubMed1978

Early and late results of aortoplasty with a left subclavian flap for coarctation of the aorta in infancy.

Between February, 1969, and December, 1976, 45 consecutive infants younger than 6 months old underwent aortoplasty with a subclavian flap for the relief of coarctation of the aorta. All infants had persistence of the ductus arteriosus, and 58 percent had associated intracardiac anomalies. The over-all hospital mortality rate was 24 percent, nad no deaths occurred in infants with coarctation associated with patent ductus arteriosus only. All the deaths were in the group of patients under 2 months of age who had associated intracardiac defects. Follow-up over a 7 year period shows no clinical, hemodynamic, or angiographic evidence of recoarctation in any of the survivors.

Aortic Coarctation↗
PubMed1977

Surgical correction of a case of common atrium with anomalous systemic and pulmonary venous drainage.

A case of common atrium with anomalous systemic and pulmonary venous connections and pulmonary stenosis is described. Surgical correction was performed by pulmonary valvotomy and the insertion of an intra-atrial pericardial baffle. To our knowledge this is the first reported case of surgical correction of total anomalous connections of both systemic and pulmonary veins. The embryologic development of this condition is discussed.

Adolescent↗
PubMed1976

The conducting tissues in primitive ventricular hearts without an outlet chamber.

We have studied the disposition of the cardiac conducting tissues in four hearts from situs solitus individuals possessing primitive ventricles without outlet chambers. These hearts correspond to the type of univentricular heart defined as common ventricle by Lev. All the hearts studied possessed normally positioned great arteries. Two groups, each consisting of two hearts, could be distinguished. The first type possessed a small posterior ridge which divided the posterior portion of the primitive ventricle into right and left ventricular sinuses. The papillary muscles to the atrioventricular valves were separate structures and arose on each side of this posterior ridge. The conducting tissues in these hearts arose from an atrioventricular node situated in the atrial septum but deviated posteriorly. The atrioventricular bundle pierced the fibrous annulus posteriorly and descended on the posterior ridge, lying to its left side. A bifurcation was not identified, and bundle branches were not present. The other two hearts had no posterior ridge. A common posterior papillary muscle supported both atrioventricular valves, and in one a marked anterior muscle bar produced obstruction of the pulmonary outflow tract. The connecting atrioventricular node was situated laterally in the right atrioventricular valve orifice, and the atrioventricular bundle descended into the right parietal wall of the primitive ventricle. A bifurcation and bundle branches were not observed. The disposition of conducting tissue in these hearts differs from that found in "primitive ventricle with outlet chamber" in that the connecting atrioventricular node and bundle are situated anteriorly and are intimately related to the transposed pulmonary artery outflow tract in the latter anomaly. The surgical significance of these findings is emphasized.

Child, Preschool↗