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Biomedical subjects

A Zacharias

Publications and source records attributed to A Zacharias.

At least 19 recordsLinked to original sources
PubMed2001

Effects of body size on operative, intermediate, and long-term outcomes after coronary artery bypass operation.

BACKGROUND: To investigate the role of body size, if any, on operative and longer term outcomes following coronary artery surgery. METHODS: A total of 3,560 consecutive patients undergoing coronary artery bypass grafting from 1991 to 1997, including 2,401 (67%) males and a mean +/- SD age of 63 +/- 10 years were ranked based on their body mass index (BMI). The association in these patients of preoperative, long-term, and economic data with variations in BMI were studied using regression analyses. Long-term survival was studied using 5-year Kaplan-Meier survival analysis. RESULTS: Operative mortality, myocardial infarction, cerebrovascular accidents, blood transfusions, and length of hospital stay were all increased in the smallest patients (BMI < or = 24 kg/m2). Obesity did not increase adverse operative outcomes except for a greater rate of sternal wound infections occurring with increasing severity of obesity. Direct variable costs were lowest in patients clustered around normal BMI, with cost increasing similarly at low and high extremes. This effect was correlated with similar BMI effects on ventilatory and intensive care requirements. Excluding operative mortality, 5-year survival trends were similarly worse for the smallest (BMI < or = 24) and most severely obese (BMI > 34) patients. Mild obesity (BMI > or = 30 to BMI < 34) did not affect long-term survival. CONCLUSIONS: Among study patients, immediate operative outcomes were adversely affected by small body size, which reflected older age (66 +/- 10 years) and an exaggerated adverse impact of cardiopulmonary bypass. Younger age and smaller effects of cardiopulmonary bypass lead to better operative outcomes in the obese. Long-term outcomes were, however, suboptimal in severely obese patients although that group was the youngest (60 +/- 10 years). In addition to their large body habitus, other factors, including substantial prevalence of diabetes, insulin dependence and hypertension, probably played a significant role in the poor long-term outcome in the severely obese.

Aged↗
PubMed2001

Disulfide bond in Pseudomonas aeruginosa lipase stabilizes the structure but is not required for interaction with its foldase.

Pseudomonas aeruginosa secretes a 29-kDa lipase which is dependent for folding on the presence of the lipase-specific foldase Lif. The lipase contains two cysteine residues which form an intramolecular disulfide bond. Variant lipases with either one or both cysteines replaced by serines showed severely reduced levels of extracellular lipase activity, indicating the importance of the disulfide bond for secretion of lipase through the outer membrane. Wild-type and variant lipase genes fused to the signal sequence of pectate lyase from Erwinia carotovora were expressed in Escherichia coli, denatured by treatment with urea, and subsequently refolded in vitro. Enzymatically active lipase was obtained irrespective of the presence or absence of the disulfide bond, suggesting that the disulfide bond is required neither for correct folding nor for the interaction with the lipase-specific foldase. However, cysteine-to-serine variants were more readily denatured by treatment at elevated temperatures and more susceptible to proteolytic degradation by cell lysates of P. aeruginosa. These results indicate a stabilizing function of the disulfide bond for the active conformation of lipase. This conclusion was supported by the finding that the disulfide bond function could partly be substituted by a salt bridge constructed by changing the two cysteine residues to arginine and aspartate, respectively.

Biological Transport↗
PubMed2000

Resource utilization in coronary artery bypass operation: does surgical risk predict cost?

BACKGROUND: Current healthcare trends may render financial risk of cardiac operation a key component of clinical decision making. It has been suggested, based on large cohorts of patients stratified by clinical risk, that the cost of operation can be predicted from models of clinical risk since length of stay (LOS) is highly correlated to clinical risk, and LOS is correlated to hospital costs and charges. Direct correlation of actual surgical costs with surgical risk are lacking. METHODS: Variable direct costs, LOS, and The Society of Thoracic Surgeons predicted mortality risk [STS risk (%)] were collected and analyzed in 628 consecutive patients undergoing coronary artery bypass grafting (CABG) at our institution in 1997. RESULTS: Cost of CABG had a near-normal distribution, and cost in 21 outlier patients (cost > two standard deviations above the mean) was an average 5.3 times normal (median cost). For individual patients, cost was well correlated to LOS (R2 = 0.48) but not with STS risk (R2 = 0.12). LOS was also poorly predicted by STS risk (R2 = 0.09). However, despite its poor prediction of cost, STS risk was an unbiased estimator over the entire population. A result manifested, when patients were grouped into similar risk (<1%, 1-2%, 2+ -3%, 3+ -5%, 5+ -10%, and >10%) cohorts, by high correlation between cost and STS risk (R2 = 0.99), cost and LOS risk (R2 = 0.99), and LOS and STS risk (R2 = 0.97). CONCLUSIONS: Our data demonstrated that, in large CABG cohorts, surgical risk models can accurately predict cost of CABG. However, despite a trend for increasing cost with increasing STS risk, surgical risk models based on preoperative data are poor predictors of cost in individual patients. Use of these models should be limited to analysis of cost trends in cardiac operation, but not for predicting financial risk in individual patients during clinical decision making.

Aged↗
PubMed2000

Long-term survival and health status after prolonged mechanical ventilation after cardiac surgery.

OBJECTIVE: To determine hospital mortality, weaning from mechanical ventilation, long-term survival, and functional health status in patients receiving > or =7 days of mechanical ventilation after cardiac surgery. DESIGN: Retrospective chart review and prospective patient interviews. SETTING: A university-affiliated, tertiary care medical center. PATIENTS: A total of 124 patients that received > or =7 days of mechanical ventilation after cardiac surgery. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Hospital and long-term death, liberation from mechanical ventilation, and functional health status. MEASUREMENTS AND MAIN RESULTS: A total of 19 (15%) patients died in hospital. Of the 105 survivors, 104 (99%) were completely weaned from mechanical ventilation. Patients who died in the hospital were more likely to have had a preoperative stroke or to have a new postoperative stroke, more likely to have postoperative renal failure, and less likely to have chronic obstructive pulmonary disease. Kaplan-Meier survival was 59% at 5 yrs and expected median survival was 6.2 yrs. Patients who died anytime after discharge were more likely to have preoperative renal dysfunction or stroke, took longer to be weaned from mechanical ventilation and to be discharged, and were more likely to have postoperative complications such as stroke or renal dysfunction. Also, they were more likely to be too debilitated to walk or eat. By multivariate analysis, admitting creatinine, aortic valve surgery, number of ventilator days, and discharged on tube feedings remained significant predictors of mortality. A total of 40 of 53 survivors were interviewed. Participants were similar to nonparticipants (p > .10 for all characteristics). A few (16%) had limitations of their activities of daily living (eating, dressing, bathing), and most had limitations of moderate activity (60%) and vigorous activity (94%). Only 36% could climb stairs or walk uphill without limitations, 54% could walk a block, and 41% had no limitations in house or job work. Half the participants had no body pain; 38% had moderate and 4% severe pain. Most (59%) described their general health as good to excellent. Only 10% said it was poor. CONCLUSION: Patients' chances of being liberated from mechanical ventilation are excellent. Their long-term survival and health status are good.

Aged↗
PubMed2000

Predictors of gastrointestinal complications in cardiac surgery.

Gastrointestinal problems are infrequent but serious complications of cardiac surgery, with high rates of morbidity and mortality. Predictors of these complications are not well developed, and the role of fundamental variables remains controversial. In a retrospective review of our cardiac surgery experience from July 1991 through December 1997 we found that postoperative gastrointestinal complications were diagnosed in 86 of 4,463 consecutive patients (1.9%). We categorized these 86 patients into 2 groups--Surgical and Medical--according to the method of treatment used for their complications. In the Medical group, 9 of 52 patients (17%) died; in the Surgical group, 17 of 34 (50%) died. By logistic multivariate analysis, we identified 8 parameters that predicted gastrointestinal complications: age greater than 70 years, duration of cardiopulmonary bypass, need for blood transfusions, reoperation, triple-vessel disease, New York Heart Association functional class IV, peripheral vascular disease, and congestive heart failure. Postoperative re-exploration for bleeding was a predictor specific to the Surgical group. Use of an intraaortic balloon pump was markedly higher in the Gastrointestinal group than in the Control group (30% vs 10%, respectively), as was the use of inotropic support in the immediate postoperative period (27% vs 5.6%). Our results suggest that intra-abdominal ischemic injury is a likely contributing factor in most gastrointestinal complications. In turn, the ischemia is probably caused by hypoperfusion due to low cardiac output, hypotension due to blood loss, and intra-abdominal atheroemboli. The derived models are useful for identifying patients whose risk of gastrointestinal complications after cardiac surgery may be reduced by clinical measures designed to counter these mechanisms.

Abdomen↗
PubMed1999

Variables predicting reintubation after cardiac surgical procedures.

BACKGROUND: This study sought to determine patient characteristics, processes of care, and intermediate outcomes as predictors of reintubation after cardiac surgical procedures. METHODS: We performed a retrospective case-control study that included all patients undergoing cardiac surgical intervention who required reintubation and an equal number of control patients not requiring reintubation. Putative risk factors were analyzed univariately by chi2, Fisher exact, Student's t, or Mann-Whitney tests. A logistic regression model was developed using data from patients requiring reintubation for cardiorespiratory reasons. RESULTS: Of the 1,000 consecutive patients reviewed, 41 (4.1%) required reintubation (30 [3%] for cardiorespiratory reasons and 11 [1.1] for unplanned operations). Univariate predictors of reintubation (p<0.05) were older age, chronic obstructive pulmonary disease, New York Heart Association functional class IV, preoperative renal failure, lower arterial oxygen tension, insertion of intraaortic balloon pump, longer time in the operating room, longer duration of cardiopulmonary bypass times, positive fluid balance, postoperative renal failure, and worse pulmonary mechanics. Patients requiring reintubation also required a longer initial period of mechanical ventilation (median, 16.3 versus 6.0 hours; p<0.05). Excellent prediction was found with a model consisting of four variables: operating room time, respiratory rate, vital capacity, and chronic obstructive pulmonary disease. CONCLUSIONS: Patients who required reintubation were sicker and had worse respiratory function and more comorbidity. Prompt extubation did not contribute to reintubation. Patients identified as having a high risk for reintubation should be followed up closely, and interventions should be directed to treating the problems leading to reintubation.

Aged↗
PubMed1997

Autoimmune diabetic neuropathy.

Recent work has shown that inflammatory vasculopathy is commonly seen in biopsies of diabetic patients with neuropathy. Most of these patients have had syndromes consistent with proximal diabetic neuropathy or amyotrophy. This suggests that inflammatory vasculopathy is important in the pathogenesis of these disorders. Immunosuppressive therapy may benefit many of these patients.

Adrenal Cortex Hormones↗
PubMed1997

Ten years of experience with isolated urachal anomalies in children.

PURPOSE: The embryological and anatomical features of urachal anomalies have been well defined. Because of the variable clinical presentation, uniform guidelines for evaluation and treatment are lacking. In an attempt to establish a cost-effective approach leading to a favorable outcome, we reviewed the experience with urachal anomalies at a single institution in a 10-year period. MATERIALS AND METHODS: We reviewed the medical records and radiological studies of 12 boys and 9 girls newborn to 17 years old at presentation who were treated for a urachal anomaly. Diagnostic evaluation included voiding cystourethrography in 14 cases, ultrasound in 8, sinography in 7 and computerized tomography in 4. RESULTS: The 4 variants of urachal anomalies included a urachal sinus in 9 patients (43%), urachal cyst in 9 (43%), patent urachus in 2 (10%) and urachal diverticulum in 1 (4%). Treatment involved initial excision in 13 cases (61%) and secondary excision in 8 (39%). Staphylococcus aureus was the predominant organism recovered. CONCLUSIONS: Because of the variable presentation, the diagnosis of a urachal anomaly can be difficult. Our experience suggests that a cost-effective diagnostic approach can be developed based on the initial clinical evaluation. Whereas ultrasound is indicated when a urachal cyst or abscess is suspected on the initial study, sinography is the study of choice in the remainder of cases. A voiding cystourethrogram may not be required in view of the fact that none of the patients studied had an additional associated urinary tract anomaly.

Adolescent↗
PubMed1996

Determinants of prolonged mechanical ventilation after coronary artery bypass grafting.

BACKGROUND: Early extubation of cardiac surgical patients enhances ambulation, improves cardiopulmonary function, and can lead to savings in health care costs. METHODS: We retrospectively examined the role of 48 variables in determining the period of ventilatory support in 507 patients having coronary artery bypass grafting. RESULTS: Fifteen (< 3%) of 507 patients required ventilatory support in excess of 24 hours. Among the remaining patients, extubation was achieved early (< or = 8 hours) (mean time, 5.65 +/- 1.31 hours) in 53% and late (> 8 hours) (mean time, 13.7 +/- 3.4 hours) in 47%. Logistic and linear multivariate regression analyses implicated increased age, New York Heart Association functional class IV, intraoperative fluid retention, postoperative intraaortic balloon pump requirement, and bank blood transfusions as predictors of late extubation. Also, the linear regression linked lower body weight and number of anastomoses (or grafts) to increased mechanical ventilatory support. CONCLUSIONS: Analysis of the fluid balance and cardiopulmonary bypass data suggests that earlier extubation may be achieved by actively reducing fluid retention (eg, by hemoconcentration) and time on bypass (eg, normothermia). Finally, intensive care unit stay and postoperative length of stay were significantly lower in the early versus late extubation groups without an increase in pulmonary complications.

Blood Transfusion↗
PubMed1996

Annular constriction of the rectum secondary to transitional cell carcinoma of the bladder.

Recurrent transitional cell carcinoma of the bladder is often a locally progressive disease. Regional lymph node metastasis is a frequent finding and may be the first sign of recurrence. Involvement of the gastrointestinal tract is rare, but metastasis to the colon, small intestine, and stomach have been reported. Herein, we present a case of recurrent transitional cell carcinoma of the bladder manifesting as an annular constricting mass of the rectum, and review the literature regarding this unusual lesion.

Aged↗
PubMed1996

Factors predisposing to median sternotomy complications. Deep vs superficial infection.

STUDY OBJECTIVES: Median sternotomy infections are a serious complication of cardiac surgery. The purpose of this study was to determine the patient characteristics and operative variables that predict incidence of sternal infection, and possibly its severity. DESIGN: Univariate and multivariate retrospective analysis comparing patient, operative, and post-operative data in patients with and without sternal infections. SETTING: Cardiac surgery program of a 580-bed private hospital in Toledo, Ohio. PATIENTS: We studied 2,317 consecutive (June 1991 to December 1994) patients undergoing cardiac surgery. RESULTS: Forty-one sternal infections were documented. Of these, 21 (0.91%) were deep infections with mediastinal involvement and 20 (0.86%) were superficial. Two patients with deep infections died (2/41, 5%). Ten variables were associated with infection by univariate analysis (p < 0.05), and of these, five were independent predictors by multivariate logistic regression. These predictors were obesity (p < 0.001), insulin-dependent diabetes (p < 0.001), use of internal mammary artery grafts (p = 0.02), surgical reexploration of the mediastinum (p = 0.003), and postoperative transfusions (p = 0.01). Predictors of deep and superficial sternal infection did not differ. Length of hospitalization was substantially longer for patients with deep (32 +/- 21 days) vs superficial infection (13 +/- 10 days). CONCLUSIONS: The present study confirms previous findings that obesity, insulin-dependent diabetes, and internal mammary artery grafting (especially bilaterally) increase the risk of sternal infection. In addition, chest surgical reexploration and blood transfusions were postoperative factors that predisposed patients with median sternotomy to infection. Unlike their associated morbidity and mortality, predictors of deep and superficial sternal infections are similar.

Analysis of Variance↗
PubMed1996

Delayed primary closure of deep sternal wound infections.

Deep infections of the sternum and mediastinum, with prevalence of osteomyelitis and tissue necrosis, were documented in 38 of 8,056 patients (0.47%) who underwent open-heart surgery (1975 through 1994) in our service. The incidences of insulin-dependent diabetes, obesity, and emergency surgery in these patients were relatively high at 39%, 47%, and 18%, respectively. Treatment with antibiotics, débridement, open packing, and delayed closure was administered to 33 patients (87%), with 100% healing. There were no deaths in this group. Flap reconstruction was indicated in 5 gravely ill patients (13%) in whom excessively large wound defects did not allow reapproximation. There were 2 deaths in this group, and 4 reoperations were necessary in the surviving patients because of sequelae arising from flap reconstruction. The overall mortality was 5.3% and the median period of hospitalization was 29 days. The length of stay decreased substantially over the period of this study (median = 21 days, year > or = 1987). Accordingly, we believe that treatment of deep sternal infections with delayed primary closure is safe and effective. Also, given the increased potential for complications and long-term sequelae, we believe that flap reconstruction should be used selectively and should be limited to patients with large defects, uncontrolled mediastinal bleeding, or both.

Adult↗
PubMed1995

Protection of the right internal mammary artery in the retrosternal position with stented grafts.

One of the limiting factors for the use of the right internal mammary artery as a pedicle graft to the anterolateral vessels of the left coronary system is the necessary midline crossover and the close proximity to the sternum. In this setting, the right internal mammary artery pedicle is at increased risk of injury during sternal reentry and dissection. A technique is described where stented polytetrafluoroethylene grafts were used to shield right internal mammary artery pedicles. There were no operative deaths or polytetrafluoroethylene-related complications. The right internal mammary artery was patent with its target vessel well perfused in 6 restudied patients.

Blood Vessel Prosthesis↗
PubMed1986

Alternative method to improve exposure for difficult mitral valve procedures.

Although the classical approaches for mitral valve surgery have remained standard over the years, variations have been described and implemented in an attempt to improve exposure of the mitral valve apparatus. A technical alternative that affords excellent exposure of the roof of the left atrium, allowing for an enlarged left atriotomy and precluding the need for more radical surgical maneuvers and their potential complications, is described.

Azygos Vein↗
PubMed1984

Microscopic study of normal parietal pericardium and unimplanted Puig-Zerbini pericardial valvular heterografts.

This investigation used light microscopy and transmission and scanning electron microscopy to study native human and bovine parietal pericardium, glutaraldehyde-fixed bovine pericardial patch-grafts, and bovine pericardial cusps of unimplanted Incor or Puig - Zerbini heart valves. The primary objective was to obtain a data base for the future evaluation of postimplantation structural alteration in this valve and in other cardiac valvular bioprostheses constructed of pericardium. The mesothelial cell layer in normal pericardium was best preserved in the bovine tissue. In both bovine patch-grafts and Puig - Zerbini valvular cusps, the serosal surface usually was completely devoid of mesothelial cells and revealed an underlying, finely fibrillar basal lamina. The fibrosa varied in thickness and organization, both within and between the two species, but similar nervous, vascular, and connective tissue components were observed in each. The epipericardial surface was smoother, had fewer elastic fibers, and possessed more surface cells in the human tissue than in the bovine tissue. No evidence of significant tissue degeneration or remodeling was noted in either the stored patch-grafts or heart valves when compared with control bovine and human pericardial tissue layers.

Animals↗
PubMed1983

Morphological alterations in dura mater encephali used as ventricular wall grafts in the canine heart.

Structural changes within homologous dura mater patch-grafts surgically implanted in the right ventricular wall of the heart were studied in nine adult dogs utilizing light microscopy and transmission and scanning electron microscopy. Physical examination of the dogs after surgery presented no clinical signs of abnormalities caused by either the surgery or the nature of the graft. After one week of implantation, a fibrous organization extending from the wound margins over the entire graft greatly increased its thickness. In addition, it was observed that (1) an increase in cellularity, vascularity and connective tissue elements occurred on the external surface of the patch-graft, (2) these same changes occurred regardless of which surface (periosteal or arachnoidal) was used as the external or pericardial surface, (3) the graft core underwent a transition from a relatively acellular and avascular connective tissue structure into one that was heavily infiltrated by a variety of cellular elements and new blood vessels, and (4) these morphological changes were interpreted as an attempt to incorporate the graft into the host tissue, resulting in an increase in both viability and stability of the graft. These findings indicate that homologous dura mater is a suitable material for use in the surgical repair of the cardiac wall.

Animals↗
PubMed1983

Study of the periosteal and arachnoidal aspects of dura mater implanted surgically in the ventricular wall of the canine heart.

After surgical removal of a portion of the cardiac wall, homologous dura mater cardiac grafts were sutured to the margins of the incision in the sternocostal wall of the right ventricle of the canine heart and recovered after 1, 4, 6 and 8 weeks of implantation. Representative tissue specimens were processed for and studied by means of SEM and TEM. The primary objectives were to study morphological changes in the dura mater grafts used to repair the lesions or defects in the cardiac wall and to compare alterations in the periosteal and arachnoidal aspects of the dura mater grafts after being implanted for varying periods of time. After one week of implantation, an amorphous layer of fibrin was deposited on or near the luminal surface of the original dura mater grafts. At four weeks of grafts implantation, a 'remodeling' process was apparent below the luminal surface of the graft. Although a large accumulation of fibrin was still present at this time, there was also an increase in the number of cellular and fibrillar components within the implant. Large numbers of macrophages and active fibroblasts were visible at this time along with new collagen. At the sixth week of implantation, an abundance of active fibroblasts, the presence of normal collagen and a darkly staining material interpreted as recently synthesized connective tissue components, fibrin deposits and/or degenerating collagen were also observed. Phagocytosis of the remaining fibrin was noted during this period indicating a continuation of the remodeling process at the luminal surface. Finally, after eight weeks of implantation, it was revealed that the original densely woven and relatively acellular graft had become infiltrated with various blood cells and vascular channels.

Animals↗