Search PubMed⌕ Search

Biomedical subjects

J Stark

Publications and source records attributed to J Stark.

At least 109 records · Page 6Linked to original sources
PubMed1990

Paralysed diaphragm after cardiac surgery in children: value of plication.

Over a 2-year period (1987-1988), 31 children (3% of 960 operations) were found to have a paralysed diaphragm following cardiac surgery. The median age was 5 months with 65% less than 1 year of age. In the 31 patients, 38 paralysed diaphragms were identified. The phrenic nerve injury was on the right in 8 cases, the left in 16, bilateral in 7 and 40% were related to modified Blalock Taussig shunts. The time to extubation was analysed for each patient in two separate groups: Group A: (greater than 1 year): 11 children of whom 5 were extubated without difficulty, 4 had non-respiratory reasons for prolonged ventilation and only 2 were plicated--both were extubated within 4 days. Group B: (less than 1 year): 20 infants of whom 16 were plicated and 4 were not. Three of the children who were plicated died from cardiac causes. Of the 13 survivors, there were 3 who had other reasons for prolonged ventilation. Thus 10 infants required prolonged ventilation (mean 11 days) because of respiratory difficulties. All underwent plication and were extubated at a mean of 2.4 days postoperatively. The 4 who were not plicated were extubated at a mean of 11 days postoperatively. In infants in whom there is no cardiac cause for failure to wean from ventilation, diaphragmatic paralysis should be suspected and plication performed if not extubated 2 weeks after operation.

Anastomosis, Surgical↗
PubMed1990

Influence of blood withdrawal and anticoagulant on clotting activity, hematologic data, and certain rheologic measurements.

The influence of blood withdrawal (vacuum or slow aspiration) and anticoagulants (ethylenediaminetetraacetic acid [EDTA]; heparin; citrate; a mixture of citrate, theophylline, adenosine, and dipyridamole [CTAD]; and D-phenylalanyl-L-prolyl-L-arginine chloromethyl ketone [PPACK]) on clotting activity, hematologic data, and rheologic measurements (whole blood and plasma viscosity, red cell filtration in one study) were investigated. No difference was found between the two blood withdrawal techniques on the basis of the affected measurements. EDTA appeared to be the best anticoagulant with regard to blood cell preservation and showed the lowest whole blood viscosity over a wide range of shear rates (0.1 to 87.0 sec-1). PPACK was the most potent inhibitor of clotting activity as monitored by fibrinopeptide A concentration. The results suggest that EDTA is probably a reasonable choice for rheologic studies of whole blood and should be combined with PPACK when plasma properties are studied.

Adenosine↗
PubMed1989

Myocardial adenine nucleotide metabolism in pediatric patients during hypothermic cardioplegic arrest and normothermic ischemia.

Quantitative assessment of high-energy phosphate levels, including degradation or utilization during ischemia, has not previously been performed in infants and children. Animal experiments suggest that high-energy phosphate metabolism varies with maturation. To help answer these questions, 24 patients aged 2 months to 8 years underwent myocardial biopsy immediately after the institution of cardiopulmonary bypass (16 to 20 degrees C). Additional samples were obtained at 16 and 45 minutes after aortic cross-clamping and administration of cardioplegia (St. Thomas's solution) (in vivo ischemia). Seven patients also underwent major myocardial resection. Resected specimens were placed in a 37 degrees C bath and divided into equal-sized samples that were removed at ten-minute intervals (in vitro ischemia). All samples were immersed in liquid nitrogen and analyzed for adenine nucleotide pool metabolites using high-performance liquid chromatography. Levels of adenosine triphosphate were high before cross-clamping but diminished during the period of protected ischemia. Adenosine triphosphate loss was much more pronounced in patients less than 18 months old (p less than 0.05) and was associated with accumulation of adenosine monophosphate and inosine, a finding not seen in patients more than 18 months old (p less than 0.05). The same trends documented during in vivo ischemia were noted during in vitro ischemia. Immaturity of 5'-nucleotidase results in accumulation of adenosine monophosphate during ischemia. It is known that 5'-nucleotidase is present in neonatal myocardial cell membranes and absent from the cytosol.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine Nucleotides↗
PubMed1989

Long-term results of homograft valves in extracardiac conduits.

Between 1971 and 1986, 335 patients received various extracardiac valved conduits between one of the heart chambers and the pulmonary arteries. The group of patients who received aortic homograft conduits and survived the operation were analysed in detail. The age varied between 9 days and 18 years (mean 7.1 +/- 0.7 years), weight 2.4 kg-63.5 kg (mean 17.8 +/- 10.8 kg). The diameter of the conduit used was 10-30 mm (mean 20.8 mm). Multivariate analysis revealed a highly significant model (P less than 0.005) which showed that the time interval between harvesting and use of the homograft (P less than 0.02) and the earlier date of operation (P less than 0.05) were the major risk factors for obstruction. Homografts used within 3 weeks of harvesting had freedom from obstruction of 79% at 8 years; homografts used between 3-6 weeks had freedom from obstruction of only 55% at 8 years. Homografts used alone performed significantly better than those extended with woven Dacron tubes. At 10 years, 93% of homografts used alone were free of obstruction compared to 52% of homografts extended with a Dacron tube. We conclude that aortic homografts used within 3 weeks of harvesting provide a reasonably durable conduit for a period of 12 years. Longer storage, and extension of the homograft with a woven Dacron tube should be avoided.

Adolescent↗
PubMed1988

Correction of coarctation of the aorta in neonates and young infants. An individualized surgical approach.

Because of the controversy concerning the ideal surgical repair for symptomatic coarctation of the aorta presenting in neonates and infants, our entire series of 179 children under the age of 12 months undergoing repair between January 1, 1976 and December 31, 1984 was reviewed. Of this group, 109 were neonates, 43 infants aged 31-90 days and 27 infants aged 90 days-12 months. Twenty patients had a simple coarctation and 159 had complex coarctation with additional intracardiac anomalies such as ventricular septal defect (37 patients also had pulmonary artery banding). One hundred and twenty-four were repaired with a subclavian flap operation, 32 with resection and end-to-end anastomosis and 23 with complex repairs (e.g. patch and reversed flap). Type of repair was the surgeon's choice and was selected on the basis of the anatomy of the coarctation. Total perioperative mortality was 15% (N = 27) while late mortality was 12% (N = 21). Twenty-one risk factors for mortality were evaluated by logistic analysis and the method of Cox. There was no risk difference between end-to-end versus subclavian flap repairs and all but one death occurred in patients with complex coarctations. Risk for in hospital death was increased by only one variable: the need for repair in the neonatal period. Risk for death in the first year of life was increased by the presence of congestive heart failure at initial presentation while later death correlated with intracardiac surgery. Recoarctation occurred in 28 patients (18.4%), all but 4 of these occurred in patients undergoing neonatal repairs.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Coarctation↗
PubMed1988

Congenital left ventricular inflow obstruction: is the outcome related to the site of the obstruction?

Between 1978 and 1987, 39 patients aged 1 day to 15 years underwent surgery for symptomatic left ventricular inflow obstruction. Four diagnostic groups were identified: cor triatriatum (6 patients), supravalvar mitral membrane (SVMM) with a normal mitral valve (7 patients), SVMM with an abnormal mitral valve (9 patients) and mitral stenosis (17 patients). Associated cardiac anomalies occurred in 26 patients (67%). There were 8 deaths (21%), 3 in patients with SVMM and an abnormal mitral valve and 5 in patients with mitral stenosis. Survival for patients with normal mitral valves was significantly better than that for patients with abnormal mitral valves (13/13 vs 18/26, P less than 0.05). There was also high morbidity in patients requiring prosthetic mitral valve replacement. These data suggest that the outcome of surgical treatment for left ventricular inflow obstruction may be predicted according to the site of the obstruction. This is best determined preoperatively by cross-sectional echocardiography which allows optimal planning of surgical strategy.

Adolescent↗
PubMed1988

Surgical creation of a double outlet right atrium for tricuspid valve stenosis after a Rastelli operation.

A patient with transposition of the great arteries, ventricular septal defect, and obstruction of the left ventricular outflow tract underwent a Rastelli repair. Stenosis of the tricuspid valve was not recognised before or during operation; this severely compromised the postoperative haemodynamic function and necessitated reoperation. Insertion of a second homograft from the right atrium to the right ventricle bypassed the stenosis and resulted in a complete recovery with maintenance of a biventricular circulation.

Child↗
PubMed1988

Arrhythmia and late mortality after Mustard and Senning operation for transposition of the great arteries. An eight-year prospective study.

Arrhythmia and late sudden death are recognized complications of intraatrial repair of transposition of the great arteries. We performed a prospective study over 8 years in 100 consecutive hospital survivors who underwent Mustard (46 patients) or Senning (54 patients) operations between 1978 and 1982. Arrhythmia was analyzed by preoperative, postoperative, and serial follow-up Holter monitoring and standard electrocardiograms and was related to clinical outcome. Before repair, all patients were in sinus rhythm with a low incidence of arrhythmia. After repair, there was a gradual decrease in stable sinus rhythm during follow-up so that at a mean of 7 years after operation only 56% of patients having the Senning operation and 66% having the Mustard, with simple transposition, were in stable sinus rhythm on Holter monitoring. There was no significant difference between the two operations. Eleven patients (five after Senning [two simple, three complex], six after Mustard [five simple, one complex]) died during follow-up, four suddenly (two after Senning, two after Mustard). However, loss of sinus rhythm or the presence of arrhythmia on standard electrocardiograms or Holter recordings did not identify patients at risk for increased morbidity or mortality. Thus, even with current surgical techniques, gradual loss of sinus rhythm occurred after both Mustard and Senning operations. Because late death could not be predicted by electrocardiographic analysis, an alternative approach involving detailed hemodynamic and electrophysiologic measurements may be required to identify high-risk patients.

Arrhythmias, Cardiac↗
PubMed1988

Surgical management of doubly committed subarterial ventricular septal defects.

The clinical presentation, diagnosis, and surgical treatment of 63 patients with doubly committed subarterial ventricular septal defects (DCVSD) were analyzed retrospectively. The patients were divided into three groups. Thirty-one patients had severe congestive heart failure in infancy and presently have a large ventricular septal defect that has no tendency to close or to produce aortic valve regurgitation (Group 1). Ideally, these defects should be closed in infancy, and the transpulmonary approach is recommended to achieve closure. In the first group, there was one death in a patient with a hypoplastic right ventricle. In Group 2, nineteen patients had aortic valve prolapse or aortic valve regurgitation. The DCVSD were moderately large or small. A number of DCVSD in Group 2 patients had maintained the normal offsetting of the arterial valves. These defects must be closed by the time mild aortic valve regurgitation has occurred. In Group 2, there was one late death in a patient who developed subacute bacterial endocarditis. The two patients who had severe aortic valve regurgitation required aortic valve replacement and underwent multiple surgical procedures to replace calcified bioprostheses. Group 3 comprised 13 patients who were diagnosed with tetralogy of Fallot. All of these patients had a large DCVSD with aortic valve overriding. All Group 3 patients survived radical repair of the defect, which required a transannular patch in most cases (76%).

Adolescent↗
PubMed1988

Surgical unifocalization in pulmonary atresia and ventricular septal defect. A realistic goal?

Between 1979 and 1986, 26 patients with pulmonary atresia, ventricular septal defect, and multifocal pulmonary blood supply underwent surgery (median age, 2 years) to reconnect major aortopulmonary collateral arteries to other collateral arteries or to the central pulmonary arteries in an attempt to prepare the pulmonary circulation for complete repair. In four patients, central pulmonary arteries were found to be absent at exploratory thoracotomy, and therefore, the surgery aimed for optimal palliation. Four (15%) patients died perioperatively. The survivors had symptomatic improvement. At restudy 1 week-110 months (median time, 25 months) postoperatively, modest growth of central pulmonary arteries had occurred [right plus left pulmonary artery diameters/descending aortic diameter from 0.64 +/- 0.61 (mean +/- SD) preoperatively to 0.95 +/- 0.60 postoperatively (p less than 0.01)], with a greater number of bronchopulmonary segments connected to central pulmonary arteries [from 6.3 +/- 4.8 preoperatively to 10.0 +/- 4.5 postoperatively (p less than 0.001)]. However, only seven (27%) patients met the established criteria for repair, of whom three (12%) have undergone definitive surgery. Thirteen (50%) patients are unsuitable for repair, and two (8%) await restudy. Failure of anastomoses involving major aortopulmonary collateral arteries (13 of 33) was higher than for grafts from a systemic artery to the central pulmonary artery (1 of 22, p = 0.003). Failure was not related to the number of anastomoses per operation, suggesting that poor distal runoff may have been responsible. This surgical approach provided reasonable palliation but was rarely effective as a prelude to complete repair.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

An introduction to independent learning skills for incoming medical students.

A partnership was initiated between educators of the College of Medicine and the McGoogan Library at the University of Nebraska Medical Center to establish a new educational component for incoming medical students. The objective was to encourage the development of the students' independent information seeking skills. A three-day seminar was introduced in which the process of seeking information was emphasized rather than the final product. Cooperative development of the seminar resulted in a fresh approach to educating medical students at the College of Medicine and the emergence of an ongoing instructional link between the library faculty and educators in the College of Medicine.

Curriculum↗
PubMed1987

Biological effects of shock waves: lung hemorrhage by shock waves in dogs--pressure dependence.

The most serious side effect observed during the destruction of gallstones by shock waves in dogs was lung bleeding. To determine the conditions leading to lung damage, pressure probes were implanted into dogs between the lung and the diaphragm. The distance between the lung and the focal point of the pressure field was determined at which 1000 shock waves caused no more lung hemorrhage. On the long axis it is greater than 15 cm and perpendicular to the long axis it is 4 cm. Shock wave pressures over 2 MPa could be administered safely, whereas a pressure of 10 MPa caused bleedings in beagles, but probably not in boxers.

Animals↗
PubMed1987

Assessment of residual right ventricular outflow tract obstruction following surgery using the response to intravenous propranolol.

The response to intravenous administration of propranolol hydrochloride was studied in 24 children undergoing operation for isolated or complex right ventricular outflow tract obstruction. Ten had pulmonary valve stenosis, 4 had pulmonary valve stenosis plus ventricular septal defect, 8 had tetralogy of Fallot, and 2 had complex lesions. Propranolol (0.01 to 0.2 mg per kilogram of body weight) was given to patients with a residual right ventricular to left ventricular systolic pressure ratio greater than 0.75. Four children did not respond to propranolol and required further surgical intervention. Twenty patients responded, 2 of whom died. Fifteen were restudied by cardiac catheterization 3 weeks to 27 months postoperatively. The right ventricle-pulmonary artery gradient was 25 mm Hg or less in 13 patients. We conclude that a small dose of propranolol given intraoperatively can identify patients in whom a reduction in the right ventricle-pulmonary artery gradient to acceptable levels will occur in the months following operation. This may reduce the need for placement of a subannular or transannular patch in some patients.

Blood Pressure↗
PubMed1987

Infective endocarditis in children with congenital heart disease: comparison of selected features in patients with surgical correction or palliation and those without.

The diagnostic and prognostic features of 44 episodes of infective endocarditis in 42 children with congenital heart disease were reviewed. Endocarditis occurred in 18 patients who had not had surgical correction or palliation of the defect (non-operated group). There were 26 episodes in 24 patients who had been treated surgically (operated group) (16 open and eight closed cardiac operations). Endocarditis occurred soon after open heart surgery in eight patients and as a late complication in the other 16. It recurred in two patients (operated group). Invasive monitoring and low cardiac output were consistent features in those patients who had endocarditis soon after open heart surgery whereas dental treatment was a common feature in non-operated cases and after closed cardiac operations. Late cases of endocarditis after open heart surgery had various microbiological features that were not typical of infection after dental problems. Gram positive infections occurred in non-operated patients and in those who had had closed cardiac operations. The group that had open heart surgery had infections caused by Gram positive, Gram negative, and anaerobic bacteria and fungi. Fever, anaemia, leucocytosis, and positive blood cultures were the only consistent findings. Vegetations were seen in nine of 12 patients at cross sectional echocardiography. All 12 (four non-operated, one closed, and seven open cases) needed acute surgical treatment. The mortality from infective endocarditis was 17% for non-operated cases, 0% for those who had had closed heart surgery, and 50% for those who had had open heart surgery. Infective endocarditis after open heart surgery differs from that in the other subgroups in terms of microbiology, source of infection, and outcome and its early diagnosis depends on a thorough investigation of minimal symptoms and signs.

Adolescent↗
PubMed1987

Transventricular aortic valvotomy for critical aortic stenosis in infants.

Ten infants with critical aortic stenosis underwent transventricular valvotomy between November 1983 and September 1984. The ages of the patients ranged from 1 to 38 days (mean 21.2 days). Three patients were less than 1 week of age. One had undergone a previous valvotomy performed with inflow occlusion. Most infants were critically ill when admitted to the hospital, six required inotropic and ventilatory support, and two had peritoneal dialysis before the operation. Transventricular valvotomy was performed through a left thoracotomy with Hegar dilators. Postvalvotomy peak-to-peak gradients ranged from 0 to 35 mm Hg. Three patients died at 2, 3, and 6 weeks after operation. A severe degree of endocardial fibroelastosis was present in one patient, and a second patient died of septicemia caused by wound infection, empyema, and a bronchopleural fistula. Severe left ventricular hypertrophy, with moderate fibroelastosis, was found at autopsy in the third patient. Aortic incompetence was not detected postoperatively. One patient required reoperation 7 months after the transventricular valvotomy. Transventricular valvotomy has proved to be a simple and effective technique to relieve aortic stenosis in sick infants. It permits the correction of associated coarctation of the aorta and avoids a median sternotomy. Results are comparable with the results obtained with either cardiopulmonary bypass or inflow occlusion as seen in both our experience and in the experience of others.

Aortic Valve↗