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Biomedical subjects

G S Weinstein

Publications and source records attributed to G S Weinstein.

At least 73 records · Page 4Linked to original sources
PubMed1990

Reduction of myocardial injury with verapamil before aortic cross-clamping.

The effect of verapamil administered before aortic cross-clamping was assessed in 40 patients undergoing elective coronary artery bypass grafting. Myocardial protection consisted of cold blood potassium cardioplegia, topical ice slush, and moderate (28 degrees C) systemic hypothermia. Patients were randomly divided into two groups: group 1 (18 patients) received verapamil (0.1 mg/kg up to 10 mg) intravenously three to five minutes before aortic cross-clamping; group 2 (22 patients) did not (control). Myocardial injury was assessed by cumulative release of the cardiac-specific isoenzyme of creatine kinase (CK-MB) after release of the aortic cross-clamp. Release of CK-MB was significantly lower in the verapamil group (44.9 +/- 6.2 versus 72.2 +/- 9.0 IU at 24.5 hours, p = 0.005). Calculated total infarct size was also lower in the verapamil group (6.0 +/- 0.9 versus 8.9 +/- 1.0 g-Eq, p = 0.035). Individual CK-MB release curves showed either one or two peaks. The two-peak pattern was more frequent in control patients (18 of 21 control patients versus 6 of 18 verapamil patients, p = 0.001) and was associated with a larger infarct size. Atrioventricular pacing was not required in any verapamil patient, but was needed in 1 control patient. We conclude that verapamil administered before aortic cross-clamping protects against myocardial injury during coronary artery bypass grafting with no increase in the incidence of atrioventricular block.

Aged↗
PubMed1990

Anomaly of the hypoglossal nerve: embryologic, anatomic, and surgical considerations.

An anomaly of the hypoglossal nerve was discovered during a procedure to anastomose the 12th and 7th cranial nerves. This anomaly is described, and an embryologic mechanism is proposed to explain the occurrence of this particular anomaly. The surgical anatomy of the hypoglossal nerve is reviewed, and reasonable approaches to the surgical identification of the hypoglossal nerve are discussed.

Anastomosis, Surgical↗
PubMed1990

Effect of oxygen free radicals and lipid peroxides on cardiac isoenzymes.

We report here the effect of oxygen free radicals, OFR (superoxide, O2-; hydroxy, OH; t-butylhydroperoxide, H2O2) lipid peroxides (malondialdehyde, MDA), free radical scavengers (superoxide dismutase, catalase, allopurinol) and generator (ferrous chloride) antioxidants (ascorbate, glutathione) spin traps (5,5-dimethyl-1-pyroline-N-oxide, N-t-butyl-L-pheny nitrone) on the cardiac isoenzyme (CK, CK-MB, LDH, LD1) concentrations in the sera of patients with acute myocardial infarction. CK-MB and LD1 were rapidly and completely inactivated by O2- (50 nmol/ml), OH (1 nmol/ml) and MDA (0.6 microM). Butylhydroperoxide (600 microM), and ferrous chloride (200 microM) selectively inhibited CK-MB. The free radical scavengers, antioxidants and spin traps all had minimal effects, and H2O2 had none.

Antioxidants↗
PubMed1989

Serial changes in renal function in cardiac surgical patients.

Cardiopulmonary bypass is widely believed to be injurious to renal function. The low incidence of renal dysfunction with modern techniques of bypass led us to reexamine this concept by monitoring urine output and creatinine clearance in 18 adult patients undergoing nonpulsatile, hemodilution cardiopulmonary bypass for coronary artery bypass grafting (12 patients) or valve procedures (6 patients). Samples were taken before, during (mean duration of bypass, 105 +/- 26 minutes [+/- standard deviation]), and every two hours after bypass for 24 hours. Urine output (42 +/- 37.7 mL/h) and creatinine clearance (57 +/- 40.4 mL/min) were surprisingly low in the period before cardiopulmonary bypass (all values normalized to a body surface area of 1.73 m2). Urine volumes rose to 305 +/- 149.6 mL/h and creatinine clearance to 252 +/- 176.9 mL/min during bypass and decreased to stable values after eight hours in the postoperative unit (urine output, approximately 60 mL/h, and creatinine clearance, approximately 75 mL/min). Renal dysfunction did not develop in any patient. Nine patients who required loop diuretics for low urine output 18 hours postoperatively had a sustained increase in both urine output and creatinine clearance lasting up to six hours. We conclude the following: modern techniques of cardiopulmonary bypass are not injurious to renal function; urine output and creatinine clearance are decreased before cardiopulmonary bypass, probably because of preoperative dehydration; and loop diuretics in the postoperative period increase both urine output and creatinine clearance for as long as six hours after administration.

Cardiopulmonary Bypass↗
PubMed1989

Effect of crossover on the statistical power of randomized studies.

Randomized studies involving long-term follow-up are vulnerable to the effects of unplanned crossover. In surgical studies, such crossover usually occurs when control patients become more symptomatic and undergo operation. In several large studies of coronary bypass grafting, crossover ranged from 25% to 38%. The most common way of dealing with this problem is to apply the "intention-to-treat" principle, which analyzes such crossovers with their originally assigned groups. Besides the logical problem of counting a control patient who actually undergoes operation as "nonsurgical," a more subtle problem arises in terms of statistical power. When statistical power is low, a truly effective treatment may be mistakenly labeled as no better than control, causing a potentially valuable form of therapy to be ignored or discarded. This analysis demonstrates that crossover may have a profound effect on the statistical power of randomized studies and presents a method for predicting the effect of such crossover on statistical power.

Coronary Artery Bypass↗
PubMed1989

Single-source outbreak of Candida tropicalis complicating coronary bypass surgery.

Candida tropicalis was isolated from the sternal wounds of eight coronary bypass patients from 18 to 89 days postoperatively; infections were limited to soft tissue in five patients but involved the sternum in three patients. Analysis of surgery records implicated one individual as the potential source of the yeast; this was confirmed by microbiological studies of fingertips and nasopharynx cultures of all personnel in contact with these patients. Only the suspect nurse, then acting as a scrub nurse and not as a circulator, infected the eight patients. Her removal from the cardiac team terminated the cluster outbreak.

Candida↗
PubMed1989

Adenoid cystic carcinoma of the parotid gland: a review of surgical management with reference to the facial nerve.

The purpose of this study was to review a large series of patients with adenoid cystic carcinoma of the parotid gland in order to develop clinical criteria for sacrifice versus selective sparing of the seventh nerve. We studied 43 patients followed over 36 years. Study patients were grouped according to the preoperative status and intraoperative management of the facial nerve. Criteria for choosing various management strategies are discussed.

Carcinoma, Adenoid Cystic↗
PubMed1989

Deferoxamine decreases necrosis in dorsally based pig skin flaps.

Deferoxamine, a free radical scavenger and iron chelator, has been shown to improve skin flap survival in ischemic flap surgery in rats. The present study investigates the value of deferoxamine in ischemic flap surgery in the porcine model. Four 4 x 12 cm flaps, 3 cm apart and 3 cm from the dorsal midline, were elevated on each of six female pigs, weighing 50 to 60 pounds each. The animals were divided into two test groups. Group 1 received six 1 gm doses of deferoxamine in 4 ml of sterile water intramuscularly every 6 hours preoperatively for five doses, followed by the administration of 1 g every 6 hours for the first 6 days postoperatively. Group 2 received 4 ml of normal saline administered intramuscularly as above. The percentage of flap necrosis was assessed on postoperative day 7 by the weighing paper technique. Group 1 had 17.1% necrosis and group 2 had 33% necrosis (p less than 0.005). Deferoxamine has decreased flap necrosis in the porcine model and may be of use in augmenting the surviving length of flaps in human beings.

Animals↗
PubMed1987

CASS and RA.

Explore the source record for details and available documents.

Clinical Trials as Topic↗
PubMed1987

Full-thickness bipedicle flap for total lower eyelid reconstruction.

We describe a technique for total lower eyelid reconstruction utilizing a full-thickness bipedicle flap from the upper eyelid. The levator aponeurosis and Müller's muscle are recessed to avoid upper eyelid retraction. The key to performing this operation is a thorough knowledge of eyelid anatomy and techniques for preserving its microvascular blood supply. The bipedicle flap requires meticulous surgical technique but has many advantages over standard types of total lower eyelid reconstruction, including the following: excellent tissue match and cosmesis are obtained with single-stage reconstruction; distal flaps and grafts are avoided; open palpebral fissure is maintained, resulting in rapid rehabilitation; posterior lamella of tarsus, rather than substitute, is utilized; anterior lamella of functional orbicularis is utilized for support and closure; pedicles suspend and support the eyelid, decreasing lower eyelid retraction, laxity, and ectropion; allows simultaneous reconstruction of canthal defects; and is faster than other forms of total lower eyelid reconstruction. The results of 14 total lower eyelid reconstructions are presented. Minor canthal deformities, the most frequent complication, are easily corrected. This technique should be considered as an alternative to other procedures in cases of total lower eyelid reconstruction.

Aged↗
PubMed1987

The renin-angiotensin system is not responsible for hypertension following coronary artery bypass grafting.

Systemic hypertension following coronary artery bypass graft (CABG) procedures has been reported to occur in 15% to 80% of cases. Previous reports have implicated the renin-angiotensin system as being responsible, at least in part, for this phenomenon. In this prospective study, 18 previously normotensive subjects were studied before, during, and after CABG. In 4 patients (22%), paroxysmal postoperative hypertension developed (systolic blood pressure greater than 150 mm Hg). There were no differences between the normotensive and hypertensive groups in plasma renin activity, angiotensin II level, or aldosterone level. Despite the trend toward elevation of these variables during cardiopulmonary bypass (CPB), all had returned to control levels within two hours after CPB, whether or not hypertension developed. Serum norepinephrine levels were elevated (.10 greater than p greater than .05) in the hypertensive group at the time hypertension developed. No other relationship or pattern could be defined to distinguish the hypertensive from the normotensive group. The renin-angiotensin system does not appear to be responsible for paroxysmal hypertension following CABG.

Adult↗
PubMed1987

Enucleation techniques: the Iowa implant.

The Iowa implant is a quasi-integrated implant with four mounds on its anterior surface. The rectus muscles are imbricated between the mounds, resulting in a socket with four protrusions that articulate with a custom-fitted prosthesis having four concavities. This imparts excellent motility and support for the prosthesis. This article describes the indications for enucleation, the Iowa implant, surgical technique, and postoperative complications.

Eye Enucleation↗
PubMed1986

Inflammation of the coronary arteries in patients with unstable angina.

During surgery, 21 patients undergoing coronary artery bypass for unstable angina were found to have "red lines" overlying one or more coronary arteries. Adventitial biopsies showed vascular distention and inflammatory cells. The group was followed for an average of 54 months (14 to 68 months). There were no operative deaths. Recurrent myocardial ischemia developed in 38.1% (8/21); recurrent angina developed in 23.8% (5/21) and are being treated medically; myocardial infarction occurred in 9.5% (2/21); and reoperation was required in 4.8% (1/21). There was also one late death from a brain tumor. We suggest that the presence of adventitial inflammation may represent an aggressive, variant form of atherosclerosis and a less favorable clinical prognosis.

Journal Article↗
PubMed1986

Clinicopathologic correlation in postendarterectomy recurrent stenosis. A case report and bibliographic review.

The case history of a 60-year-old man with symptomatic recurrent stenosis of the left carotid artery 20 years after carotid endarterectomy is presented. At reoperation (repeat endarterectomy and venous patch angioplasty) the lumen was found to be reduced by 60% and histopathologic study revealed atheromatosis with organizing mural thrombus. The case is discussed in the context of the recent literature concerning restenosis, the reported frequency of which varies depending on the size of the population studied and the method of follow-up, with noninvasive studies revealing that restenosis is more commonly asymptomatic than symptomatic. Early simple fibrous restenosis differs histologically from the more complex, frankly atherosclerotic late restenosis and appears to reproduce the original pathologic condition of the carotid bifurcation; as in the original lesions hemodynamic conditions probably play a major etiologic role in the formation of the restenoses. The most important clinical factor in restenosis is continued cigarette smoking. In the majority of the studies reviewed, more than half of the patients with recurrent disease presented with symptoms referable to the site of the original operation. An argument in favor of routine vein patching during the primary procedure to attempt to prevent restenosis is presented.

Adult↗