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Biomedical subjects

N Moazami

Publications and source records attributed to N Moazami.

At least 19 recordsLinked to original sources
PubMed2001

Safety and efficacy of intraarterial thrombolysis for perioperative stroke after cardiac operation.

BACKGROUND: Acute ischemic stroke after cardiac operations is a devastating complication with limited therapeutic options. As clinical trials of thrombolysis for acute ischemic stroke exclude patients with recent major surgery, the safety of intraarterial thrombolysis in this setting is unknown. METHODS: Thirteen patients with acute ischemic stroke within 12 days of cardiac operation underwent intraarterial thrombolysis within 6 hours of stroke symptom onset. The National Institutes of Health Stroke Scale was used to assess neurologic recovery. RESULTS: The mean age was 69 years (standard deviation +/-5 years) and 62% were men. Cardiac procedures included valve operations in 6 patients, coronary artery bypass grafting in 4, valve and coronary artery bypass grafting in 2, and left ventricular assist device in 1 patient. Atrial fibrillation occurred in 5 patients (38%). The mean time from operation to stroke was 4.3 days (standard deviation +/- 3 days). Thrombolysis was initiated within 3.6 hours (standard deviation +/-1.6 hours) of stroke symptom onset. Recanalization was complete in 1 patient, partial in 5, and 7 patients had low flow. Neurologic improvement occurred in 5 patients (38%). One patient needed a chest tube for hemothorax, 2 others were transfused for low hemoglobin. No operative intervention for bleeding was necessary. CONCLUSIONS: In select patients with acute ischemic stroke after recent cardiac operation, intraarterial thrombolysis appears to be reasonably safe and may lead to neurologic recovery.

Aged↗
PubMed2001

Clinical experience with 202 adults receiving extracorporeal membrane oxygenation for cardiac failure: survival at five years.

OBJECTIVES: We sought to determine 5-year survival after extracorporeal membrane oxygenation for cardiac failure and its predictors, to assess survival and its predictors after bridging to transplantation or weaning from extracorporeal membrane oxygenation, and to identify factors influencing the likelihood of these outcomes. METHODS: Two hundred two adults (mean age, 55 +/- 14 years) were supported with extracorporeal membrane oxygenation between 1992 and July 1999 after cardiac failure. Follow-up extended to 7.5 years (mean, 3.8 +/- 2 years). Multivariable hazard function analysis identified predictors of survival, and logistic regression identified the determinants of bridging or weaning. RESULTS: Survival at 3 days, 30 days, and 5 years was 76%, 38%, and 24%, respectively. Patients surviving 30 days had a 63% 5-year survival. Risk factors (P <.1) included older age, reoperation, and thoracic aorta repair. Forty-eight patients were bridged to transplantation, and 71 were weaned with intent for survival. Survival was similar after either outcome (44% vs 40% 5-year survival, respectively). Failure to bridge or wean included (P <.03) renal and hepatic failure on extracorporeal membrane oxygenator support, occurrence of a neurologic event, and absence of infection. The dominant modes of death were cardiac failure and multisystem organ failure. CONCLUSIONS: Extracorporeal membrane oxygenation is versatile and salvages some patients who would otherwise die. Improvement in intermediate-term outcome will require a multidisciplinary approach to protect organ function and limit organ injury before and during this support.

Adolescent↗
PubMed1998

Preformed IgG antibodies against major histocompatibility complex class II antigens are major risk factors for high-grade cellular rejection in recipients of heart transplantation.

BACKGROUND: Preformed anti-HLA antibodies reacting specifically with donor lymphocytes have been associated with acute vascular rejection and early cardiac allograft failure. However, the effect of preformed anti-HLA antibodies directed against allogeneic major histocompatibility complex (MHC) class I or II antigens of a donor panel on heart transplantation outcome has not been extensively studied. METHODS AND RESULTS: The study group consisted of 68 patients who received cardiac transplants between 1989 and 1996 and who were at high risk for developing anti-HLA antibodies before transplantation. The effect of preformed antibodies against allogeneic MHC class I or class II antigens on the development of early high-grade cellular rejection and on cumulative annual rejection frequency was determined. Both patients with left ventricular assist devices and retransplantation candidates had a similar increase in the frequency of IgG anti-MHC class II antibodies (IgG anti-II) compared with control subjects (P<0.0001), whereas the frequency of IgG anti-MHC class I antibodies (IgG anti-I) was elevated only in patients with left ventricular assist devices. Pretransplantation IgG anti-II predicted early development of high-grade cellular rejection (P=0.006) and higher cumulative annual rejection frequency (P<0.001) in both of these sensitized patient groups. Among retransplantation recipients, a match between donors 1 and 2 at HLA-A additionally predicted an earlier time to a high-grade cellular rejection. CONCLUSIONS: These results emphasize the importance of specifically screening heart transplantation candidates for the presence of IgG antibodies directed against MHC class II molecules and suggest that strategies aimed at their reduction may have an impact on the onset and frequency of high-grade cellular rejections after transplantation.

Adolescent↗
PubMed1998

Short-term outcome of chronic immunosuppression on the development of breast lesions in premenopausal heart and lung transplant patients.

The risk of development of breast lesions in patients on chronic immunosuppression is unknown. In order to assess this risk, a retrospective review was performed of the records of 87 women between the ages of 12 and 47 years who received thoracic organ transplant from 1987 to 1996 at our institution. Inclusion criteria consisted of patients who were premenopausal, had no previous history of breast disease, and survived for at least 1 year posttransplantation. All patients were on a triple immunosuppressive regimen consisting of cyclosporine, steroids, and azathioprine. Mean follow-up was 4 +/- 1.2 years with a range of 1-6 years. During this period, 21 patients (24%) with a mean age of 38 +/- 10 years had screening or diagnostic mammography. The remainder of patients with a mean age of 24 +/- 9 years were followed clinically. Overall, 10 patients (11%) developed a total of 17 palpable, solid lesions at 33 to 72 months posttransplantation. Fifteen of these lesions were surgically excised. Five of the patients had multiple lesions. Pathological examination of the specimens revealed fibroadenoma in nine, fibrocystic disease in four, low grade phylloides tumor in one, and T-cell lymphoma in one case. None of the patients have developed primary breast cancer during follow-up. In conclusion, short-term immunosuppression does not increase the risk of the development of benign breast lesions in young women after thoracic organ transplantation, but rather the distribution of benign lesions is similar in an age-matched population. There were several cases of multiple fibroadenomas in the transplant population, but mammography revealed no malignant disease in this age group and does not need to be utilized in this population beyond what is considered standard for immunocompetent patients. The long-term effect ofimmunosuppressive therapy on the developmentof breast cancer in this group remains to be defined.

Adolescent↗
PubMed1998

Inflow valve regurgitation during left ventricular assist device support may interfere with reverse ventricular remodeling.

BACKGROUND: Left ventricular assist devices have been reported previously to reverse ventricular remodeling in patients with dilated cardiomyopathy. In patients with prolonged mechanical support, structural failure of the left ventricular assist device inflow valve can cause regurgitation into the left ventricle, which may affect adversely this process. METHODS: Left ventricular end-diastolic pressure-volume relation of hearts explanted from 8 patients with left ventricular assist device and 8 control subjects with idiopathic cardiomyopathy was determined ex vivo at the time of transplantation. RESULTS: Duration of mechanical support ranged from 210 to 276 days (mean +/- standard deviation = 283 +/- 76 days) in 3 patients with inflow valve regurgitation versus 100 to 155 days (132 +/- 22 days) in 5 patients without (p = 0.005). The end-diastolic pressure-volume relation of all hearts supported mechanically was shifted to the left toward normal controls. This effect was markedly attenuated in patients with inflow valve regurgitation. CONCLUSIONS: Mechanical assistance can cause reverse remodeling in patients with dilated cardiomyopathy as evidenced by the shift in the end-diastolic pressure-volume relation curve to the left. Inflow valve failure, associated with prolonged support, can attenuate changes in left ventricular structure and dimension. Ineffective pressure and volume unloading may explain these observations.

Cardiomyopathy, Dilated↗
PubMed1998

Randomized, double-blind trial of inhaled nitric oxide in LVAD recipients with pulmonary hypertension.

BACKGROUND: Pulmonary vascular resistance is often elevated in patients with congestive heart failure, and in those undergoing left ventricular assist device (LVAD) insertion, it may precipitate right ventricular failure and hemodynamic collapse. Because the effectiveness of inotropic and vasodilatory agents is limited by systemic effects, right ventricular assist devices are often required. Inhaled nitric oxide (NO) is an effective, specific pulmonary vasodilator that has been used successfully in the management of pulmonary hypertension. METHODS: Eleven of 23 patients undergoing LVAD insertion met criteria for elevated pulmonary vascular resistance on weaning from cardiopulmonary bypass (mean pulmonary artery pressure > 25 mm Hg and LVAD flow rate < 2.5 L x min[-1] x m[-2]) and were randomized to receive either inhaled NO at 20 ppm (n = 6) or nitrogen (n = 5). Patients not manifesting a clinical response after 15 minutes were given the alternative agent. RESULTS: Hemodynamics for the group at randomization were as follows: mean arterial pressure, 72 +/- 6 mm Hg; mean pulmonary artery pressure, 32 +/- 4 mm Hg; and LVAD flow, 2.0 +/- 0.3 L x min(-1) x m(-2). Patients receiving inhaled NO exhibited significant reductions in mean pulmonary artery pressure and increases in LVAD flow, whereas none of the patients receiving nitrogen showed hemodynamic improvement. Further, when the nitrogen group was subsequently given inhaled NO, significant hemodynamic improvements ensued. There were no significant changes in mean arterial pressure in either group. CONCLUSIONS: Inhaled NO induces significant reductions in mean pulmonary artery pressure and increases in LVAD flow in LVAD recipients with elevated pulmonary vascular resistance. We conclude that inhaled NO is a useful intraoperative adjunct in patients undergoing LVAD insertion in whom pulmonary hypertension limits device filling and output.

Administration, Inhalation↗
PubMed1998

Inhaled nitric oxide is not a myocardial depressant in a porcine model of heart failure.

BACKGROUND: Inhaled nitric oxide has been shown to be a potent and selective pulmonary vasodilator. Reports of increases in left ventricular end-diastolic pressure and episodes of pulmonary edema during the clinical use of inhaled nitric oxide in patients with preexisting left ventricular dysfunction have raised concerns that this agent may have myocardial depressant effects. We therefore undertook a study of the effects of inhaled nitric oxide on myocardial contractility in a porcine model of ventricular failure and pulmonary hypertension. METHODS: After inducing heart failure in 10 pigs by rapid ventricular pacing, hemodynamic measurements and pressure-volume diagrams (by the conductance method) were obtained in six animals at baseline and during administration of inhaled nitric oxide at concentrations of 20 and 40 ppm. Myocardial contractile state was assessed by the end-systolic pressure-volume relationship and preload-recruitable stroke work, whereas diastolic function was measured in terms of the end-diastolic pressure-volume relationship and the pressure decay time constant T. RESULTS: Baseline hemodynamics reflected heart failure and pulmonary hypertension, and inhaled nitric oxide induced significant reductions in mean pulmonary artery pressure and pulmonary vascular resistance. Although left ventricular end-diastolic pressure increased during administration of inhaled nitric oxide, no changes were observed in measures of systolic or diastolic function. CONCLUSIONS: Inhaled nitric oxide reduced pulmonary vascular resistance but did not alter myocardial contractility or diastolic function. Increases in left ventricular end-diastolic pressure during inhaled nitric oxide therapy are therefore not due to myocardial depression and may be related to increases in volume delivery to the left side of the heart resulting from reduced pulmonary vascular resistance.

Animals↗
PubMed1998

Platelet transfusions are associated with the development of anti-major histocompatibility complex class I antibodies in patients with left ventricular assist support.

BACKGROUND: Preformed anti-human leukocyte antigen (HLA) antibodies delay heart transplantation in patients with left ventricular assist devices (LVAD) because of difficulty in finding crossmatch-negative donors. These antibodies may also be associated with adverse outcome after transplantation. METHODS: In a retrospective analysis of 40 patients with LVAD at Columbia-Presbyterian Medical Center between 1990 to 1996, age, sex, diagnosis, race, duration of support, transfusions, and infections were studied by univariate and multivariate analysis as predictors for development of either anti-HLA class I (anti-I) or anti-HLA class II (anti-II) immunoglobulin G (IgG) or M (IgM) antibodies. RESULTS: Eighteen (45%) patients had development of anti-I and 20 (50%) had development of anti-II antibodies over the study period. Median time for LVAD support was 142 days (range 35 to 439). Only total number of perioperative platelet transfusions predicted the development of anti-I IgG antibodies (p = .04). No other associations were found for development of anti-I IgM or anti-II antibodies of either IgG or IgM specificity. Patients who had development of anti-I IgG received a mean of 13.9 (SE +/- 2.6) units of platelets compared with a mean of 7.7 (SE +/- 2.3) units in those who did not (p = .01). By Kaplan-Meier analysis, at the median duration of follow-up, 8% of patients receiving < 6 units were predicted to have development of anti-I antibodies compared with 63% receiving > 6 units (p = .002). In the last 7 patients, leukocyte filters were used to decrease the antigenic load during platelet and red blood cell transfusions. Only 1 of 7 (14%) patients had development of anti-HLA antibodies compared with 31 of 33 (94%) in whom filters were not used (p < .005). CONCLUSIONS: These results indicate that platelet transfusion during LVAD implantation is a risk factor associated with development of HLA class I IgG antibodies. Use of leukocyte filters during platelet transfusion may decrease the risk of development of anti-HLA antibodies.

Antibody Formation↗
PubMed1997

Circulatory resuscitation with left ventricular assist device support reduces interleukins 6 and 8 levels.

BACKGROUND: Elevated tumor necrosis factor serum levels have been reported in patients with severe congestive heart failure. This study was designed to characterize the cytokine profile in patients with acute circulatory collapse. METHODS: Blood drawn from 14 consecutive patients within 24 hours before undergoing left ventricular assist device placement and after at least 30 days of mechanical assistance or before transplantation was assayed for levels of interleukin 6, interleukin 8, and tumor necrosis factor-alpha. RESULTS: Interleukin 6 level was elevated in 11 (79%), interleukin 8 in 10 (71%), and tumor necrosis factor in 2 (14%) of the 14 patients. After hemodynamic recovery, interleukin 6 levels decreased from 33.6 +/- 9 pg/mL to 11.3 +/- 4 pg/mL (p = 0.05) and interleukin 8 levels decreased from 122 +/- 34 pg/mL to 19.7 +/- 8 pg/mL (p = 0.005). Tumor necrosis factor-alpha levels did not vary significantly; they were associated with infection in 2 left ventricular assist device recipients and normalized after left ventricular assist device support. All patients had resolution of circulatory shock after mechanical support and had improvement in parameters of end-organ function. CONCLUSIONS: Circulatory shock treated with left ventricular assist device placement is associated with a proinflammatory response similar to that seen in septic shock. The decrease in cytokine serum levels that follows hemodynamic recovery suggests that these cytokines may be markers of tissue damage and may modulate cardiac dysfunction.

Biomarkers↗
PubMed1997

The influence of infection on survival and successful transplantation in patients with left ventricular assist devices.

BACKGROUND: Mechanical cardiac assistance has recently emerged as a tenable option in the treatment of end-stage heart failure. In spite of recent technical improvements that have reduced the incidence of life-threatening complications, the reported frequency of infections in these patients has remained high. METHODS: Over a 5-year period, 60 patients underwent insertion of a left ventricular assist device (LVAD) at our institution. Detailed medical records were kept prospectively for all patients, and a variety of endpoints were analyzed, including the incidence, nature, and sequelae of infections before and after LVAD implantation and after transplantation. RESULTS: Twenty-nine of 60 patients (48%) undergoing LVAD insertion subsequently had development of infections. The most frequent sites of infection were blood, LVAD drivelines, and central venous catheters, representing 61% of all infections. At the time of LVAD implantation, 13 of 60 patients (22%) had culture-proven infections. In spite of an increased incidence of subsequent infection (77% vs 40%), there were no differences in rates of mortality (31% vs 26%), LVAD endocarditis, (23% vs 11%) and eventual transplantation (62% vs 57%) between these patients and those without periimplantation infections. Although the overall mortality rate was not influenced by infections during LVAD support (28% vs 26%), the development of LVAD endocarditis was associated with a high mortality rate. Finally, although patients with infections during LVAD support had significantly longer median support times than those who remained infection free (101 vs 49 days, respectively), there was no difference in the rate of successful transplantation (59% vs 58%) or in the rate of infection after transplantation (35% vs 28%). CONCLUSIONS: Infections are common in patients undergoing LVAD support, but they do not adversely affect survival, the rate of successful transplantation, or the incidence of posttransplantation infection. Periimplantation infections may increase the risk of subsequent infections, but they also do not influence survival or transplantability. Patients with development of LVAD endocarditis are at increased risk for morbidity and death and require early and aggressive therapy, potentially including device explantation.

Adolescent↗
PubMed1996

Extended indications for lung volume reduction surgery in advanced emphysema.

BACKGROUND: Lung volume reduction surgery has shown early promise as a palliative therapy in severe emphysema. Selection of potential candidates has been based on certain functional and anatomic criteria, and a variety of operative contraindications have been proposed. METHODS: Over 15 months, we performed lung volume reduction surgery in 85 patients selected on the basis of severe hyperinflation with air trapping, diaphragmatic dysfunction, and disease heterogeneity. Patients were not excluded on the basis of severe hypercapnia, steroid dependence, profound pulmonary dysfunction, or inability to complete preoperative rehabilitation. RESULTS: We observed significant improvements in pulmonary function, exercise capacity, and dyspnea, with an acceptable 30-day perioperative mortality of 7% and actuarial survival of 90% and 83% at 6 and 12 months, respectively. In each "high-risk" group, perioperative mortality, actuarial survival to 1 year, and functional results were equivalent, and in some cases superior, to those in the corresponding "low-risk" patients. CONCLUSIONS: Severe hypercapnia, steroid dependence, profound pulmonary dysfunction, and inability to complete preoperative rehabilitation do not preclude successful lung volume reduction surgery and should not be regarded as absolute exclusionary criteria.

Aged↗
PubMed1992

Changes in type I collagen following laser welding.

Selection of ideal laser parameters for tissue welding is inhibited by poor understanding of the mechanism. We investigated structural changes in collagen molecules extracted from rat tail tendon (> 90% type I collagen) after tissue welding using an 808 nm diode laser and indocyanine green dye applied to the weld site. Mobility patterns on SDS-PAGE were identical in the lasered and untreated tendon extracts with urea or acetic acid. Pepsin incubation after acetic acid extraction revealed a reduction of collagen alpha and beta bands in lasered compared with untreated specimens. Circular dichroism studies of rat tail tendon showed absence of helical structure in collagen from lasered tendon. No evidence for covalent bonding was present in laser-treated tissues. Collagen molecules are denatured by the laser wavelength and parameters used in this study. No significant amount of helical structure is regenerated on cooling. We conclude that non-covalent interactions between denatured collagen molecules may be responsible for the creation of tissue welding.

Animals↗
PubMed1990

Reinforcement of colonic anastomoses with a laser and dye-enhanced fibrinogen.

The incidence of anastomotic leakage in colonic surgery is approximately 10%. We evaluated a technique of laser-fibrinogen reinforcement to strengthen experimental colonic anastomoses. The technique consisted of the topical application of indocyanine green dye-enhanced fibrinogen to the serosal surface of two-layer inverting anastomoses, followed by exposure with an 808-nm diode laser. In the 28 rabbits used for this study, mean bursting pressure at time 0 was 108 +/- 13 mm Hg in the group receiving anastomoses with sutures alone and 173 +/- 20 mm Hg in the group for which the sutured anastomosis was reinforced with laser-fibrinogen. The difference in bursting pressures between the two groups was statistically significant at time 0. However, at 1, 3, 5, and 7 days, the anastomosis became stronger in both groups and the difference in strength was reduced; the sutured group had more exceptionally weak (less than 110 mm Hg) bonds than the group treated by laser. Thus, laser-fibrinogen reinforcement significantly enhances the early strength of sutured colonic anastomoses. This technique may reduce the incidence of leakage during the first postoperative week and the associated complications in a clinical setting.

Anastomosis, Surgical↗
PubMed1989

Salmonella typhimurium histidinol dehydrogenase: complete reaction stereochemistry and active site mapping.

The stereochemistry of the L-histidinol dehydrogenase reaction was determined to be R at NAD for both steps, confirming previous results with a fungal extract [Davies, D., Teixeira, A., & Kenworthy, P. (1972) Biochem. J. 127, 335-343]. NMR analysis of monodeuteriohistidinols produced by histidinol/NADH exchange reactions arising via reversal of the alcohol oxidation reaction indicated a single stereochemistry at histidinol for that step. Comparison of vicinal coupling values of the exchange products with those of L-alaninol and a series of (S)-2-amino-1-alcohols allowed identification of the absolute stereochemistry of monodeuteriohistidinols and showed that histidinol dehydrogenase removes first the pro-S then the pro-R hydrogens of substrate histidinol. The enzyme stereochemistry was confirmed by isotope effects for monodeuteriohistidinols as substrates for the pro-R-specific dehydrogenation catalyzed by liver alcohol dehydrogenase. Active site mapping was undertaken to investigate substrate-protein interactions elsewhere in the histidinol binding site. Critical binding regions are the side-chain amino group and the imidazole ring, whose methylation at the 1- or 2-position caused severe decreases in binding affinity. Use of alternative substrates further clarified active site interactions with the substrate. Compounds in which the alpha-amino group was replaced by chloro, bromo, or hydrogen substituents were not substrates of the overall reaction at 1/10,000 the normal rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol Oxidoreductases↗
PubMedDate not supplied

Bouveret's syndrome: diagnosis by helical CT scan.

Calculous cholecystitis severe enough to result in pyloric outlet obstruction is a rare occurrence. Impaction of a large calculus in the duodenum or stomach as a consequence of fistula formation is usually diagnosed on upper gastrointestinal series. Computed tomography is uncommonly used to diagnose this condition and was diagnostic in our patient.

Biliary Fistula↗
PubMedDate not supplied

Photo-oxidized bovine arterial grafts: short-term results.

Biologic grafts are the conduit of choice for vascular reconstructive procedures. The short-term thrombogenicity, patency, and stability of bovine arterial grafts, altered by a dye-mediated photo-oxidation process, was evaluated in the canine common femoral vein (CFV) and artery (CFA) model. Modified bovine interposition grafts were implanted in the CFV of 12 dogs and in the CFA of 11 dogs, respectively. Polytetrafluoroethylene (PTFE) implants on the contralateral side served as controls. Patency and histology were assessed at 1, 2, 4, and 6 weeks. In the CFV, patency of photo-oxidized grafts was 83% at 1 week and 71% at 2 weeks, compared to 17% and 0% for PTFE, respectively (p = 0.0033). In CFA, patency was 82% for the photo-oxidized graft and 63% for PTFE at 6 weeks (p = NS). Photo-oxidized grafts were nonreactive, without evidence of degenerative changes or cellular infiltration at all time periods. Compared to commercially available PTFE, photo-oxidized arterial grafts have superior patency in the CFV, and comparable patency in the CFA. Preliminary results demonstrate that these xenografts are stable and without degenerative changes. If corroborated by long-term data, these grafts may be a suitable alternative to currently available prosthetics for peripheral vascular reconstructive procedures.

Animals↗