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Biomedical subjects

D R Walker

Publications and source records attributed to D R Walker.

At least 73 records · Page 4Linked to original sources
PubMed1987

Right lower lobe consolidation: an unusual complication of the modified Blalock-Taussig operation.

Persistent right lower lobe consolidation in a 5-year-old girl is described. In infancy she had been diagnosed to have tricuspid atresia and pulmonary stenosis, and she had undergone a modified Blalock-Taussig shunt using a polytetrafluoroethylene tube graft at the age of 1 year. The shunt had parasitized and then occluded the right main bronchus. At bronchoscopy, the shunt was removed. The pneumonia resolved, and the child remains well 10 months later. This complication of the modified Blalock-Taussig shunt, which does not appear to have been reported previously, demonstrates the need for bronchoscopy in unresolving pneumonia in childhood.

Arteriovenous Shunt, Surgical↗
PubMed1987

Aortic valve damage caused by operative balloon dilatation of critical aortic valve stenosis.

Operative balloon dilatation of the aortic valve was performed in seven neonates with critical stenosis of the aortic valve. The procedure was followed by the development of severe aortic regurgitation in four patients. Necropsy was performed in three and revealed partial detachment of the right coronary cusp of the aortic valve. Damage to the valve leaflet caused by balloon dilatation was probably the result of using a balloon with a diameter that was too large in relation to the aortic valve ring diameter and of shearing forces created in the aortic wall by the contracting ventricle. The diameter of the inflated balloon should not be larger than the diameter of the aortic valve ring.

Angioplasty, Balloon↗
PubMed1986

Surgical treatment of idiopathic mediastinal fibrosis: report of five cases.

Idiopathic mediastinal fibrosis is a rare disease of unknown aetiology. It is a benign condition in which abnormal proliferation of fibrous tissue occurs within the mediastinum, leading to constriction and obliteration of local structures, particularly the great veins. It is a rare cause of superior vena caval obstruction (1-2%) but one that is potentially amenable to surgical palliation. The results of venous reconstruction in five patients with superior vena caval obstruction secondary to idiopathic mediastinal fibrosis are reported. Reversed autogenous saphenous vein grafts were used in two patients, woven silicone rubber prostheses in two, and bovine pericardial conduits in one patient. Useful long term results were obtained in three patients, but the bovine pericardial graft and one of the vein grafts failed within a few weeks.

Adult↗
PubMed1983

Calcification of glutaraldehyde-preserved porcine and bovine xenograft valves in young children.

Eight children (mean age, 7.6 years) had xenograft prosthetic valves inserted. All developed evidence of prosthetic valve obstruction requiring reoperation 18 to 55 months after insertion (mean, 32 months). At operation, all the valves were found to be heavily calcified. There were two perioperative deaths. Of two patients who had a second xenograft valve inserted, one died suddenly 12 months later. Gross calcification of the xenograft was found at postmortem examination. The other patient had evidence of mild xenograft calcification at follow-up 19 months postoperatively. Four of the ten calcified xenograft valves were of bovine origin (Ionescu-Shiley type); in these the calcific obstruction occurred significantly earlier than in the six porcine (Hancock) valves.

Aortic Valve Stenosis↗
PubMed1983

Management of neonatal posterolateral diaphragmatic hernia.

From March 1978 to April 1982 13 neonates with a left posterolateral diaphragmatic hernia were seen in respiratory distress within 12 hours of birth. Each had severe acidosis and hypoxia. They were immediately intubated and ventilated. Arterial and central venous lines were inserted, the acidosis was partially corrected, and a dopamine infusion of 4-8 micrograms/kg/min was begun immediately. Continuous monitoring of arterial and venous pressures, core and skin temperatures, blood gases, and pH was instituted. Diaphragmatic defects were repaired by direct suture in nine neonates and by Gore-Tex patches in four. The left lung in all patients was hypoplastic. Ventilation and inotropic support were continued for four to five days after operation and close control of acid-base balance was maintained. All but one survive and are doing well. We consider the key to survival to be management of the dangerous combination of acidosis (by enhancing peripheral and renal perfusion with dopamine) and hypoxia (by prolonged assisted ventilation).

Diaphragm↗
PubMed1983

Surgical management of severe coarctation of the aorta in the first month of life.

Between March, 1978, and April, 1982, 48 neonates under 4 weeks of age were operated upon for severe coarctation of the aorta in our unit. Of these, 36 babies were in severe congestive cardiac failure and 11 had renal failure. Angiocardiography and echocardiography demonstrated intracardiac lesions in 29 patients. All had a patent ductus arteriosus. Surgical relief of the coarctation was effected within 48 hours of diagnosis. Those in severe cardiac and renal failure were intubated and ventilated in the intensive care unit before the operation. Continuous monitoring of the central venous and arterial pressures and rectal and skin temperature and periodic checks on the acid-base status were instituted, and acidosis was corrected carefully with a 4.2% solution of sodium bicarbonate. A dopamine infusion (4 to 8 micrograms/kg/min) was used to assist the renal and cardiac functions. Five babies were treated with prostaglandin E for 24 to 46 hours before the operation. Forty-five patients had subclavian flap repair of the coarctation and the other three had repair by polytetrafluoroethylene (PTFE) patch angioplasty. The patients were ventilated for 1 to 8 days postoperatively. Dopamine support was given to all the immediate postoperative period. Three patients with associated cardiac lesions died in the first 48 hours after operation. Three other patients died on the sixth, eighth, and eleventh postoperative days of noncardiac causes. Of the 42 survivors, three required revision of the repair because of restenosis 3 to 18 months later. Three patients with ventricular septal defect had closure of the defect within 8 months after birth. We believe that coarctation of the aorta presenting soon after birth should be treated by a combination of active resuscitation and early surgical relief, and that continuous monitoring for early detection and correction of hypoxia and acidosis is essential to achieve satisfactory results.

Acidosis↗
PubMed1982

The management of neonatal posterolateral diaphragmatic hernia.

Between March, 1978, and August, 1980, 7 neonates with a left posterolateral diaphragmatic hernia were seen in respiratory distress within 12 hours of birth. Each had severe acidosis and hypoxia. They were immediately intubated and ventilated. Arterial and central venous lines were inserted, the acidosis was partially corrected, and a dopamine infusion of 5 microgram/kg/min was begun immediately. Continuous monitoring of arterial and venous pressures, core, and skin temperatures, blood gases, and pH was instituted. Diaphragmatic defects were repaired by direct suture in 5 neonates and by Gore-Tex patches in the other 2. The left lung in all patients was hypoplastic. Ventilation and inotropic support were continued for 4 to 5 days post-operatively, and close control of acid-base balance was maintained. All the patients are doing well. We consider the key to survival to be management of the dangerous combination of acidosis (by enhancing peripheral and renal perfusion with dopamine) and hypoxia (by prolonged assisted ventilation).

Dopamine↗
PubMed1980

Myocardial protection during cardioplegia in open-heart surgery: a review.

The use of cardioplegia (pharmacologically induced electromechanical arrest) to achieve the ideal conditions for cardiac surgical operations was introduced over 20 years ago in clinical practice. Since then a number of ingredients have been added in various proportions to different cardioplegic solutions and their evaluation in experimental laboratories and clinical practice has continued. Any additive to a cardioplegic solution should be investigated in experimental laboratories and asanguinous cardioplegic solutions should be carefully formulated to avoid extremes of ionic concentrations, pH and osmolarity. Cold blood cardioplegia has not been found advantageous when compared with conventional asanguinous solutions. A combination of pharmacologically induced arrest with cold asanguinous cardioplegic solution and topical hypothermia protects the myocardium better than topical hypothermia alone or normothermic cardioplegia, and continuous infusion of cardioplegic solutions has proved no better than multidose administration. Multidose administration of cold cardioplegic solutions with moderate hypothermia and surface cooling has been found most satisfactory for prolonged aortic cross clamping (up to two hours). Use of cardioplegia in recent years has undoubtedly improved the prognosis of a number of patients undergoing surgical correction of complex cardiac lesions.

Cardiac Surgical Procedures↗
PubMed1980

Dopamine infusion for the treatment of myocardial dysfunction associated with a persistent transitional circulation.

Four infants with myocardial dysfunction associated with a persistent transitional circulation were given dopamine infusions in addition to standard treatment. The condition of each improved strikingly with rapid diminution in heart size as judged by chest x-ray. Dopamine has a place in the management of the sick infant with a persistent transitional circulation.

Dopamine↗
PubMed1978

Minnesota Multiphasic Personality Inventory prediction of intellectual changes following cardiac surgery.

One hundred two cardiac surgery patients were tested with the Minnesota Multiphasic Personality Inventory (MMPI) preoperatively and 98 of these patientts (two diet, two were untestable) were tested both pre- and postoperatively with the Wechsler Adult Intelligence Scale, Bender-Gestalt, and the Wechsler Memory Scale. A large number of the patients obtained preoperative "neurotic"-type MMPI profiles. Postoperative deficits in intellectual ability were slight for the group as a whole, however, there was marked within-group variance. The MMPI was not found to be useful as a predictor of postoperative intellectual changes.

Adult↗
PubMed1975

Correction of tricuspid atresia.

Although Fontan and Baudet in 1971 described a physiological correction procedure for tricuspid atresia, very few successful operations have been reported. Two patients corrected 20 and 10 months ago at the Brompton Hospital are presented. These two patients exhibit many of the problems in the management of tricuspid atresia. The first patient aged 20 had undergone three previous palliative operations, a Blalock-Taussig shunt, a Glenn procedure, and an infundibular resection, and therefore presented a number of operative problems. In contrast the second patient, aged 8, whose condition had deteriorated considerably over the previous year, had had no previous surgical treatment. At operation he was found, in addition, to have a partial atrioventricular canal. Details of the operative procedures and the patients' postoperative course are described. The criteria for selection of patients for the Fontan operation are discussed as are the possible long-term hazards of homograft failure, atrial dysrhythmias, and hepatic dysfunction. The successful outcome of these two patients suggests that palliative surgery in infancy should allow for this form of correction in later life.

Adult↗