Biomedical subjects
Publications and source records attributed to J Stark.
This article has reviewed the most recent thoughts and findings on the pathophysiology and care of ARF. Clearly, we still have much to learn, but an updated practitioner is necessary in order to meet the challenges of this complex disease, as we search for tomorrow's answers.
The control of ovulation in mammalian species appears to be a highly robust process. The primary mechanism is believed to be competition amongst a group of developing follicles, mediated by a hormonal feedback loop involving in the first instance the pituitary. Successful follicles reach maturity and ovulate, the remainder atrophy and die. A model of this control process has been derived by Lacker and his group. Based on simple qualitative assumptions about the hormonal feedback loop, this is able to reflect many of the basic physiological features of ovulation in mammals. However, a fundamental hypothesis of Lacker's work is that all follicles are identical and respond to hormonal signals in precisely the same way. Not only is this improbable, but it also leads to several aspects of the model which are qualitatively unrealistic, most notable of these is its inability to accurately model the condition known as Polycystic Ovary Syndrome. This common malfunction of the ovulatory control mechanism accounts for up to three-quarters of cases of anovulatory infertility in humans and its understanding is therefore of considerable medical significance. In this paper we extend the analysis of Lacker's model to the case of non-identical follicles; this allows us to obtain behaviour much closer to that observed in PCOS patients and to draw some tentative conclusions about the mechanisms underlying this condition.
BACKGROUND: Open heart operations in young children may lead to myocardial swelling and increased lung water. Decreased intrathoracic space may then make sternal closure difficult. Delayed sternal closure may be beneficial in this setting. Potential risks of delayed sternal closure are sepsis and sternal instability. METHODS: To assess these risks, we reviewed retrospectively 150 consecutive children who underwent delayed sternal closure after repair of complex congenital cardiac defects. RESULTS: Diagnoses included transposition of the great arteries (66), total anomalous pulmonary venous drainage (11), and complete atrioventricular septal defects (10). Age at operation was 229 +/- 51 days (mean +/- standard error of mean). Sixteen patients required extracorporeal membrane oxygenation. Survival was 88% (133 patients). The sternum was left open for 3.86 +/- 0.29 days. Fifteen patients had minor wound infections requiring antibiotics. No patient required reexploration for mediastinitis and no patient had an unstable sternum. CONCLUSIONS: Delayed sternal closure with sternal stenting and silicone membrane skin closure is a safe procedure in infants and children with compromised cardiac output after repair of congenital cardiac defects.
The patient, a 17 year old boy, had undergone a Rastelli operation for transposition of the great arteries plus ventricular septal defect and left ventricular outflow tract obstruction at the age of 7 years. Associated tricuspid valve stenosis was treated with insertion of a second homograft shortly after the Rastelli operation. The patient remained symptom-free for 10 years, when he suffered femoral artery embolus. Investigation showed severe obstruction of both conduits and biventricular dysfunction with thrombus in the left ventricle. After embolectomy and stabilisation of his general condition and prolonged treatment with heparin, he underwent uneventful replacement of the two conduits. He remains well, 8 months after the operation.
AIM: Atrioventricular septal defect and tetralogy of Fallot is a relatively uncommon lesion in which there is a risk of right ventricular dysfunction related to inlet and outlet valve problems. For this reason, conservative management involving an initial palliative procedure is often chosen. The aim of this report is to retrospectively review our experience with this lesion. PATIENT POPULATION: 35 patients with atrioventricular septal defect and tetralogy of Fallot have been surgically managed at this institution between January 1980 and June 1995. Twenty-one (60%) of these patients underwent 28 initial palliative shunt procedures. Fourteen (40%) patients underwent primary definitive repair. The criteria for choosing one management strategy over another was based on a number of factors, including age at presentation, anatomy of the lesion, and severity of symptoms. Of the 21 patients who underwent an initial shunt procedure, 15 have undergone definitive operation. Of the 6 patients who did not undergo definitive operation, three died (two directly related to complications of the shunt procedure), two are awaiting operation, and one was lost to follow-up. RESULTS: The primary indication for operation in all patients was cyanosis. Freedom from reoperation at 5 years after definitive operation was 65.1% for all patients; most reoperations were related to left atrioventricular valve regurgitation or residual leaks across the ventricular septal defect patch. The operative mortality at definitive operation was 10.3% (70% CL 4.5-20%) for all patients. The actuarial estimate of survival 7 years following definitive repair was 77.3% (70% CL 68.7-85.9%) for all patients. The actuarial estimate of survival at 7 years was 84.4% (70% CL 73.8-95%) in the patients undergoing primary repair and 65% (70% CL 52.4-77.6%) in patients initially palliated if the mortality of the palliative shunt procedure is included (P = 0.35). CONCLUSION: Patients with atrioventricular septal defect and tetralogy of Fallot can be successfully managed with a variety of surgical strategies. Primary repair may be a reasonable option in carefully selected patients, as this eliminates the morbidity and mortality of an initial shunt procedure and the subsequent interval between initial palliation and definitive repair.
The new species Penicillium discolor, frequently isolated from nuts, vegetables and cheese is described. It is characterised by rough, dark green conidia, synnemateous growth on malt agar and the production of the secondary metabolites chaetoglobosins A, B and C, palitantin, cyclopenin, cyclopenol, cyclopeptin, dehydrocyclopeptin, viridicatin and viridicatol. It also produces the mouldy smelling compounds geosmin and 2-methyl-isoborneol, and a series of specific orange to red pigments on yeast extract sucrose agar, hence the epithet discolor. P. discolor resembles P. echinulatum morphologically but on basis of the secondary metabolites is also related to P. expansum, P. solitum and P. crustosum.
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BACKGROUND: Resternotomy for repair of congenital cardiac defects can result in cardiac injury. Closure of the pericardium during the initial operation may prevent this, and several pericardial substitutes have been tried, with variable results, in patients in whom primary pericardial closure is not possible. We conducted a multicenter observational study of the use of the expanded polytetrafluoroethylene membrane (Preclude Pericardial Membrane, formerly called the Gore-Tex Surgical Membrane; W. L. Gore & Associates, Flagstaff, AZ) in patients likely to undergo reoperation for treatment of congenital heart disease. METHODS: Data were collected retrospectively on all patients in whom the expanded polytetrafluoroethylene membrane was inserted at the initial operation for congenital heart disease at 12 centers in 1984 to 1993. RESULTS: A total of 1,085 patients (mean age, 55 +/- 2.5 months) received the membrane. During follow-up ranging from 1.3 to 10.5 years, 105 reoperations were performed. Injury during resternotomy occurred in only 1 patient (1% of reoperations). There were no membrane-related deaths or complications in the entire series of 1,085 patients. CONCLUSIONS: The expanded polytetrafluoroethylene membrane was safe and effective in helping to prevent cardiac injury during resternotomy for treatment of congenital heart disease.
OBJECTIVES: The aim of this report is to examine the short-and intermediate-term outcome of a complex biventricular repair compared with a single ventricle repair in patients with two functional ventricles. PATIENT POPULATION: Since 1986, 34 patients with atrioventricular concordance or discordance, ventriculoarterial discordance, ventricular septal defect, and pulmonary stenosis or atresia have undergone biventricular repair (group I). Another group of 16 patients (group II) with the same diagnoses have undergone a single ventricle repair consisting of a total cavopulmonary connection because of either a straddling atrioventricular valve (11 patients) or an uncommitted ventricular septal defect (5 patients). RESULTS: The mean length of follow-up was 3.9 years in group I and 3.0 years in group II. Freedom from reoperation at 7 years was 45.5% in group I and 100% in group II (p = 0.014). The actuarial estimate of survival at 7 years was 68.0% in group I and 93.8% in group II (p = 0.048). CONCLUSION: Short- and intermediate-term morbidity and mortality were greater in patients undergoing a biventricular repair than in a similar group of patients undergoing total cavopulmonary connection. It is unknown whether the long-term results of a total cavopulmonary connection in patients with two ventricles are as good as those obtained with a biventricular approach. However, there may be situations in which the short- and intermediate-term risks of a complex biventricular repair may outweigh the long-term disadvantages of a single ventricle approach.
OBJECTIVE: The aim of this report is to review the surgical experience of a single institution with a relatively large series of patients with mixed total pulmonary venous drainage. PATIENT POPULATION: Between January 1, 1971, and December 31, 1994, 232 patients with total pulmonary venous drainage underwent surgical correction. Twenty of these patients (8.6%) had mixed type total pulmonary venous drainage. Ages at operation ranged from 1 day to 46 months, with a median of 2.3 months. RESULTS: Both cardiac catheterization and echocardiography were performed before operation in 12 patients. Four patients underwent only cardiac catheterization, and another four patients underwent only echocardiography. The sensitivity and specificity for catheterization were 94% and 99%, respectively; they were 31% and 100%, respectively, for echocardiography. Severe pulmonary venous obstruction was present in three patients, all of whom underwent emergency operation. Three patients (15%), all of whom had preoperative pulmonary venous obstruction, died after operation. There were two late deaths, one of pulmonary vein stenosis and the other of probable pulmonary hypertension. The actuarial survival at 10 years was 73% for all patients; patients who survived the initial operation had a 10-year survival of 87%. CONCLUSION: The diagnosis of mixed total pulmonary venous drainage can be difficult to establish by echocardiography or at the time of operation. For patients in stable condition, cardiac catheterization may be considered if fewer than three pulmonary veins are identified by echocardiography. Pulmonary venous obstruction is relatively infrequent in this group of patients but when present impacts patient survival significantly. The long-term results with this lesion are excellent.
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OBJECTIVE: Discordant atrioventricular (AV) connection is a rare congenital cardiac anomaly. Associated cardiac defects modify the physiology, clinical presentation, and surgical management of these patients. We have reviewed our overall experience with 90 patients operated for lesions associated with AV discordance between 1975-1990. METHODS: 90 patients, consecutively operated between 1975-1990, were reviewed. Patients' charts, angiograms and echocardiograms were studied. Follow-up was obtained from our records or was requested from referring cardiologists/paediatricians. It was completed in December 1992. For the analysis of risk factors of early death we used P values by chi-squared and Fisher's exact test. For the analysis of the triangulated events, we used the Kaplan-Meier method. Variables associated with P value over 0.20 were eliminated. RESULTS: 90 patients aged 6 months-30 years (mean 9.1 year) underwent repair of cardiac anomalies associated with AV discordance. Three patients had total cavopulmonary connection; the remainder received biventricular repair. Most important associated malformations were ventricular septal defect (77), subpulmonary obstruction (68) and tricuspid valve anomaly (21). 59 patients received extracardiac valved conduit, 10 had tricuspid valve replacement. Thirteen patients died in hospital (14%). One year and 10 year actuarial survival rate was 84% and 70% respectively. The most significant factors for early death were: anatomically abnormal tricuspid valve (P < 0.0001), tricuspid valve regurgitation (P < 0.002), date of operation (P < 0.012), preoperative or perioperative complete heart block (P < 0.015), and tricuspid valve surgery (P < 0.05). Complete heart block developed in 17 (20%) out of 85 patients who did not have it preoperatively. During the follow-up, 22 intracardiac reoperations were necessary (4 died). 63 patients of 73 survivors (86%) remain in NYHA Class 1, 6 in Class 2 and 4 in Class 3. CONCLUSIONS: The operative mortality was 14%. Twenty per cent of patients developed complete heart block. These results improved in the later part of the series (1985-1990); mortality decreased to 5% and incidence of heart block to 14%. Cardiac anomalies associated with AV discordance still present a surgical challenge. The data reported in our study should serve as a useful baseline for evaluation of newer surgical techniques, such as the "double switch" operation.
A 4-month-old infant presented with aneurysm of patent ductus arteriosus (PDA) which was causing obstruction of the left main bronchus. The patient had elevated pulmonary vascular resistance (PVR) at 6.1 um2. The aneurysm was resected on cardiopulmonary bypass. The patient required phenoxybenzamine and prostacycline after the operation for elevated PVR. Postoperative progress was prolonged but 12 months after surgery the patient is well, growing normally without any respiratory symptoms.
OBJECTIVE: To evaluate the results of closure of muscular ventricular septal defects through a left thoracotomy. METHODS: Records of 23 children operated consecutively between 1972 and 1990 were studied. Age of patients was 2.8 +/- 3 years (2 months-10 years), weight 8.9 +/- 5.7 kg (2.6-22 kg). Ten patients (43%) had undergone one and 4 patients (17%) two previous cardiac operations. Late follow-up was obtained from direct examination of patients or from reports of their referring physicians. Bypass time was 89 +/- 28 min (66-167 min). The aorta was cross-clamped for 44 +/- 15 min (21-66 min). Until 1977 operations were performed with moderate hypothermia and intermittent aortic cross-clamping. After 1978 deep hypothermia (20-25 degrees C) and cold crystalloid cardioplegia was used. Ventricular septal defects not accessible from other approaches were closed through a small fish-mouth incision in the apex of the left ventricle. Patients' data were sampled and stored in a computerised database. Risk factors were evaluated by stepwise logistic regression. RESULTS: Four patients died in the hospital (17%); two died later. Two required reoperation for residual/recurrent defects. All patients, except two from abroad, were available for follow-up, which ranged from 36 months to 18 years (mean 11.3 years). All were in NYHA class I. Only two risk factors were identified: the number of ventricular septal defects (P < 0.05) and associated atrial septal defect (P < 0.02). Early echocardiographic evaluation showed good LV size and function in all except one patient, who had a perioperative septal infarction. Late echocardiography performed in six patients demonstrated normal LV shortening without evidence of regional wall abnormality. CONCLUSIONS: Left ventriculotomy is a useful approach for closure of low muscular ventricular septal defects in selected patients.
OBJECTIVE: To evaluate our early experience with the combined Rastelli and atrial switch operation for repair of discordant atrioventricular connection associated with ventricular septal defect and left ventricular outflow tract obstruction. METHODS: Detailed study of the first three cases including preoperative assessment, operative procedure, postoperative progress and follow-up. RESULTS: All three patients survived and remained in sinus rhythm. Postoperative ITU/hospital stay was 2/8, 5/10 and 33/45 days. The third patient developed a venous pathway obstruction and required balloon dilatation with stenting on the 25th postoperative day. All three patients were well at follow-up examination 21, 6 and 5 months after operation. CONCLUSIONS: We believe that this operation is likely to become the operation of choice for this combination of lesions. More experience and longer follow-up is needed.