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Biomedical subjects

A Montoya

Publications and source records attributed to A Montoya.

At least 37 records · Page 2Linked to original sources
PubMed1996

Arterial impedance in patients during intraaortic balloon counterpulsation.

BACKGROUND: Symptomatic improvement of a patient's hemodynamic condition during intraaortic balloon counterpulsation (IABC) is considered to result largely from a reduction in afterload. Afterload can be accurately quantified by arterial input impedance measurements. Here we report the effect of IABC on arterial impedance in humans. METHODS: To characterize the effects of IABC on arterial input impedance, impedance measurements were obtained using aortic annulus Doppler flow and pressure from the aortic balloon catheter. Impedance spectra were compared between the cardiac cycles preceding and following the cycle with IABC in 25 patients. RESULTS: Intraaortic balloon counterpulsation increased stroke volume (23%; p = 0.001), reduced myocardial oxygen demand (11%; p = 0.02), and decreased the aortic pressure at the onset of systole (16%; p = 0.001). There was also a decrease in systemic vascular resistance (24%; p = 0.001), characteristic arterial impedance (21%; p = 0.002), and pulse wave reflection (20%; p = 0.006). Linear regression analysis showed that an increase in stroke volume was predicted only by the decrease in systemic vascular resistance (r = -0.81; p = 0.001). CONCLUSIONS: The reduction in systemic vascular resistance appeared to be the major mechanism by which IABC improved cardiac pumping efficiency. This effect may result from the passive distention of the peripheral vascular bed due to the propagation of the balloon-augmented diastolic pressure through the arterial system.

Aged↗
PubMed1996

Natural history of allograft coronary arteriopathy: a retrospective study of 54 patients over a 8 1/2-year period.

A total of 288 patients underwent heart transplantation at Loyola University Medical Center over a 8 1/2-year period starting in March, 1984. Of these patients, 54 were identified as having allograft coronary arteriopathy. Diagnosis was made on the basis of abnormal findings on coronary angiography in 44 patients; either an autopsy or explanted heart revealed the diagnosis in the remainder. A total of 279 abnormal lesions were identified by coronary angiography, and over 70% of these stenoses were discrete and located in large epicardial vessels. The left ventricular ed-diastolic pressure demonstrated a steady rise over time (2.5 mmHg/year), and also correlated with the degree of allograft coronary arteriopathy stenosis. The rate of stenosis progression was 33% per year from the time of initial allograft coronary arteriopathy development. Actuarial survival rate was lower than that of patients with arteriopathy. In conclusion, first, the majority of allograft coronary arteriopathy stenoses detected on coronary angiography are discrete, involve large epicardial vessels, and progress rapidly over time. Second, left ventricular end-diastolic pressure seems to reflect the degree of allograft coronary arteriopathy stenosis, and may prove to be a useful indicator of left ventricular dysfunction related to allograft coronary arteriopathy. Third, patients with allograft coronary arteriopathy show a decreased actuarial survival rate.

Actuarial Analysis↗
PubMed1996

Topography of cardiac ganglia in the adult human heart.

Published descriptions of the topography of cardiac ganglia in the human heart are limited and present conflicting results. This study was carried out to determine the distribution of cardiac ganglia in adult human hearts and to address these conflicts. Hearts obtained from autopsies and heart transplant procedures were sectioned, stained, and examined. Results indicate that the largest populations of cardiac ganglia are near the sinoatrial and atrioventricular nodes. Smaller collections of ganglia exist on the superior left atrial surface, the interatrial septum, and the atrial appendage-atrial junctions. Ganglia also exist at the base of the great vessels and the base of the ventricles. The right atrial free wall, atrial appendages, trunk of the great vessels, and most of the ventricular myocardium are devoid of cardiac ganglia. These findings suggest modifications to surgical procedures involving incisions through regions concentrated with ganglia to minimize arrhythmias and related complications. Repairs of septal defects, valvular procedures, and congenital reconstructions, such as the Senning and Fontan operations, involve incisions through areas densely populated with cardiac ganglia. The current standard procedure for orthotopic heart transplantation severs cardiac ganglia and their projections to nodal and muscular tissue. One modification of the current heart transplantation procedure, involving bicaval anastomosis, preserves atrial anatomy and the cardiac ganglia. Preservation of cardiac ganglia within the donor heart may provide additional neuronal substrate for intracardiac processing and targets for regenerating nerve fibers to the donor heart.

Adult↗
PubMed1996

Post-lung transplant biopsies: an 8-year Loyola experience.

A total of 125 transplant procedures involving the lung have been performed at Loyola University of Chicago in 120 patients. There were 67 single (40 right, 27 left), 44 bilateral single, 2 double lung, and 12 heart-lungs (HL) transplant procedures. This paper summarizes the pathologic findings in 565 transbronchial, 102 endobronchial, 20 open lung, and 92 endomyocardial biopsies and compares them with the recommendations in the published literature. The lung biopsies were evaluated according to the Working Formulation, Lung Rejection Study Group, International Society of Heart Transplantation. In transbronchial biopsies, all of which were from the transplanted lungs, the number of alveolated lung fragments ranged from 0 to 14 (mean, 5). Two hundred twelve biopsies showed no rejection, 113 had minimal rejection, 133 had mild rejection, 34 had moderate rejection, and 1 had severe acute rejection. Active airway damage (Grade B) was seen in 48 biopsies, which were graded from minimal to severe based on the amount of inflammation. Chronic rejection (Grade C) was diagnosed in 23, chronic vascular rejection (Grade D) in 8, and acute vasculitis (Grade E) in 9 biopsies. Routine trichrome and elastic van Gieson stains did not add to the diagnosis. All biopsies were routinely stained with immunoperoxidase for cytomegalovirus. Cytomegalovirus was diagnosed in 84 biopsies, 54 by both H&E and immunoperoxidase, 23 by immunoperoxidase alone, and 5 by H&E alone. The endobronchial biopsy of the anastomotic site had nonspecific inflammation in 46 biopsies. Twenty-nine had infection with a specific organism, Aspergillus and Candida in each of 8 biopsies by Gomori's methenamine silver stain, cytomegalovirus in 7 (4 by H&E and immunoperoxidase; 3 by immunoperoxidase), bacteria in 4, and fungal hyphae in 2 biopsies. In the 12 patients with heart-lung transplants, a total of 92 endomyocardial, 35 transbronchial, and 1 endobronchial biopsies were obtained. Acute rejection was seen only in 2 endomyocardial biopsies, whereas the transbronchial biopsy showed acute mild or moderate rejection in 10, chronic rejection in 1, and cytomegalovirus infection in six biopsies. We conclude that: (a) all biopsies with alveolated lung parenchyma can be evaluated for rejection and infection yielding clinically significant diagnoses; (b) sections from three levels stained by H&E are essential for evaluation; (c) routine Gomori's methenamine silver, elastic van Gieson, and trichrome stains are not required for transbronchial biopsy, however, routine Gomori's methenamine stain is recommended for all anastomotic site biopsies; (d) routine immunoperoxidase for cytomegalovirus is extremely helpful; (e) Grade B rejection should be further graded; and (f) endomyocardial biopsy played no significant role in the management of heart-lung recipients.

Acute Disease↗
PubMed1996

Postmortem findings in lung transplant recipients.

Lung transplantation is now an accepted modality for treating end-stage lung disease. To better understand the factors limiting the survival of these patients, we reviewed the autopsy findings in 37 patients who received lung transplants. Between 1986 and 1995, 131 patients have undergone lung transplantation at our institution, including 4 patients with repeat transplantations. Of these, 48 (36.6%) died, 37 (77%) of whom had an autopsy. The autopsied patients were divided into three groups on the basis of post-transplantation interval: early (< 30 d), intermediate (31-365 d), and late (> 365 d). Of the 12 patients in the early group, 6 died of intra- and postoperative complications and 6 of bacterial infection with pneumonia in the transplanted lung. There were 18 patients in the intermediate group, of whom 11 died of infection (5 of cytomegalovirus, 5 of nonviral infections of the transplanted lung, and 1 of encephalomyelitis), 3 of post-transplantation lymphoproliferative disorder, 3 of chronic airway rejection, and one of unrelated cause. Of the seven patients in the late group, four died of chronic airway rejection, two of unrelated causes, and one of bacterial infection. Native lungs examined in 23 patients showed, in addition to the primary disease, bacterial pneumonia in 5, post-transplantation lymphoproliferative disorder in 3, cytomegalovirus in 2, and aspergillosis in 1. In this series of 37 autopsied patients, chronic rejection was the cause of death in 7 and was concomitantly seen in 3 patients (27%). In summary, the most common cause of death was infection (48%), followed by chronic rejection (19%), surgical complications (19%), post-transplantation lymphoproliferative disorder (7%), and unrelated causes (7%); rejection was not a major cause of death in the early and intermediate post-transplantation periods; in 30% of native lungs, significant pathologic findings were present in addition to the primary disease; and in the intermediate post-transplantation period, significant left ventricular hypertrophy occurred, which may be attributable to cyclosporine-induced hypertension but which needs to be further studied.

Adolescent↗
PubMed1995

DNA flow cytometry of canine mammary tumours: the relationship of DNA ploidy and S-phase fraction to clinical and histological features.

The DNA ploidy status and S-phase fraction (SPF) of benign proliferative lesions (BPL) and malignant tumours (MT) in the mammary glands of dogs were determined by flow cytometric analysis and the results were related to their clinical and histological features. Seven (14.3 per cent) of 49 BPL and 16 (48.5 per cent) of 33 primary MT had aneuploid G0,1 peaks (P < 0.001). Hypodiploid G0,1 peaks were found in one BPL and in five primary MT. The DNA ploidy status of primary MT was not found to be associated with their size, nodal status, grade of histological malignancy or nuclear grade. In several cases there was intra-tumour heterogeneity in ploidy status independent of histological heterogeneity. The SPF was significantly higher in 27 primary MT than in 45 BPL when diploid and aneploid cases were combined for comparison (P < 0.05), but not when only diploid cases were compared. Among the primary MT the SPF was higher in aneuploid than in diploid tumours (P < 0.05) and it was higher in five MT from five dogs with regional disease than in 22 MT from 19 dogs with local disease (P < 0.05). The SPF was positively correlated with the grade of histological malignancy (P < 0.05) but not with nuclear grade.

Animals↗
PubMed1994

Chronic cardiac rejection masking as constrictive pericarditis.

The hemodynamic changes consistent with constrictive pericarditis are often encountered in patients who have undergone cardiac transplantation. We describe here 4 patients who underwent pericardiectomy after cardiac transplantation. All were found to have evidence of a thickened and constricting peel of pericardium at surgical exploration. Their postoperative clinical courses were variable. One patient with primarily effusive constriction experienced marked improvement. Three patients failed to show clinical improvement and had persistently elevated atrial and ventricular end-diastolic pressures. A coexisting restrictive cardiomyopathy secondary to chronic rejection, coronary arteriopathy, or long-standing constriction may have been the cause of this poor outcome. Many patients with transplanted hearts exhibit evidence of poor diastolic ventricular compliance without evidence of classic constriction; some manifest both the restrictive and constrictive components. The careful selection of patients with constrictive pericarditis can optimize the outcome.

Adult↗
PubMed1994

Survival and functional outcome after single and bilateral lung transplantation. Loyola Lung Transplant Team.

BACKGROUND: The experience at Loyola University Chicago was retrospectively reviewed to evaluate survival and functional outcome after single lung transplantation (SLT) and bilateral lung transplantation (BLT). METHODS: Ninety patients underwent lung transplantation at Loyola University Chicago between April 1990 and December 1993. Mean age was 45 years (range, 13 to 66 years). Fifty percent were male. Pre-lung transplant pulmonary diseases were as follows: emphysema and/or chronic obstructive pulmonary disease in 43 patients, pulmonary fibrosis in 13, cystic fibrosis in 14, pulmonary hypertension in eight, repeated transplantation for obliterative bronchiolitis in four, bronchiectasis in two, bronchoalveolar cell carcinoma in two, sarcoidosis in one, primary obliterative bronchiolitis in one, histiocytosis X in one, and lymphangiomyomatosis in one. Fifty-seven patients underwent SLT, and 33 had BLT. Maintenance immunosuppression medications consisted of cyclosporine, azathioprine, and prednisone. RESULTS: Perioperative complications were as follows: seven of 33 patients bled after BLT, and two of 57 bled after SLT. Bronchial complications were found in six of 66 (9%) BLT anastomoses and eight of 57 (14%) SLT anastomoses. Nine operative deaths occurred in SLT patients: six from allograft failure, one from infection, one from intrapulmonary hemorrhage, and one from bronchial dehiscence. Only two patients died in the perioperative period after BLT and that was of infection. Three late deaths occurred after BLT, all as a result of infection; 13 recipients died late after SLT: five of infection, four patients from lymphoma, two of pancreatitis, one of tension pneumothorax, and one of pulmonary embolism. For the entire patient population the actuarial 1- and 2-year survival rates were 72% and 68%, respectively. One-year survival rates were significantly better for patients undergoing lung transplantation for obstructive and nonrestrictive lung diseases than those of patients undergoing lung transplantation for vascular or restrictive pulmonary disease. Recipients of BLT had a trend toward better survival than recipients of SLT. Lung function 6 months after transplantation measured by forced expiratory volume in 1 second was significantly better in BLT than SLT, 71% of predicted versus 54%. CONCLUSIONS: Patients who undergo BLT have significantly better postoperative pulmonary function than those who undergo SLT. On the basis of the study there was a trend toward better survival with BLT.

Adolescent↗
PubMed1993

The Loyola University lung transplant experience.

BACKGROUND: We reviewed our experience with isolated lung transplantation at Loyola University Medical Center, Maywood, Ill. From April 1990 through June 1992, 33 lung transplantations for end-stage pulmonary disease were performed (30 single lung, three bilateral single lung). Recipient diagnoses include chronic obstructive pulmonary disease, alpha 1-antiprotease deficiency, pulmonary fibrosis, primary pulmonary hypertension, Eisenmenger's syndrome, sarcoidosis, cystic fibrosis, bronchiectasis, and bronchiolitis obliterans. METHODS: For patients who underwent transplantation for end-stage obstructive airway disease, we retrospectively reviewed functional indexes before and after transplantation. In addition, the overall survival rate was determined. RESULTS: Successful transplantation resulted in a marked improvement in functional capacity. Single-lung transplantation for end-stage obstructive airway disease resulted in a threefold improvement in the 1-second forced expiratory volume, from 0.49 to 1.64 L. The actual survival for all isolated lung transplant recipients (including both single-lung and bilateral single-lung procedures) was 73%, with a 15% 30-day mortality. CONCLUSION: Isolated lung transplantation can significantly improve functional capacity as well as the quality of life in patients with end-stage lung disease.

Actuarial Analysis↗
PubMed1993

Comparison of a monoclonal antibody-based enzyme-linked immunosorbent assay and gas chromatography for the determination of nicotine in cigarette smoke condensates.

A competitive enzyme-linked immunosorbent assay (ELISA) based on monoclonal antibodies was developed to measure nicotine in smoke condensates of cigarettes. The ELISA standard curve displays a detection limit of 70 ng/mL and an effective working range of 0.3-4.0 micrograms of nicotine/mL. Using standard samples, ELISA results compare well with theoretical values (r = 0.997). The suitability of the method for industrial routine application was evaluated by measuring the nicotine concentration in 245 cigarette smoke condensates. When ELISA results were compared with those obtained by gas chromatography, a correlation coefficient r = 0.886 was obtained. The assay allows the specific, precise, and accurate determination of nicotine, without any significant interference from other alkaloids also present in tobacco smoke. Preliminary data suggest that the immunoassay could also be applied to other matrices, e.g., tobacco extracts. ELISA equipment requirements are minimum, simple, and low-cost, and an unskilled person could perform 150 analysis in a working day. On the basis of these features, ELISA is proposed as a promising alternative to instrumental methods for some industrial applications.

Animals↗
PubMed1993

Heart and lung grafts harvested en bloc: operative technique, utilization, and results.

Combined heart and lung transplantation has been shown to provide successful therapy for patients with end-stage heart and lung disease. The improved success of lung transplantation has resulted in increasing number of potential recipients and longer waiting times. Maximal utilization of all three thoracic organs is no longer a casual goal but of utmost necessity. We devised a new technique that improves operative visualization, decreases dissection time, and ensures excellent preservation of all three thoracic organs. Bench dissection after extraction of this heart-lung block allows the thoracic and cardiac surgeons to agree on precise dissection of the left atrium and adequate pulmonary venous and atrial cuff. This technique has been used in 48 of our last 50 harvests with excellent results. Utilization of heart and lungs has been 93% and 74%, respectively.

Heart↗
PubMed1993

Infective aortic endocarditis after percutaneous balloon aortic valvuloplasty.

Infective aortic endocarditis developed in an elderly patient after a percutaneous balloon aortic valvuloplasty. The transesophageal echocardiogram demonstrated a perivalvular abscess. The patient underwent surgical replacement of the infected valve, but later succumbed to renal failure. The development of infective aortic endocarditis should be recognized as a potentially fatal complication of percutaneous balloon aortic valvuloplasty. The important measures in preventing bacteremia during percutaneous balloon aortic valvuloplasty and the appropriate role of operation are discussed.

Aged↗
PubMed1993

Nonthoracotomy lead system for implantable defibrillator.

Over a 2-year period, 110 patients underwent attempted implantation of an automatic cardioverter-defibrillator using the nonthoracotomy lead system. Indications included sustained monomorphic ventricular (n = 62), nonsustained with poor ventricular function (n = 7), ventricular fibrillation (n = 21), ventricular tachycardia/fibrillation (n = 18), and familial long QT syndrome (n = 2). There were 90 male and 20 female patients. Mean age was 57 +/- 15 years. Sixty percent had previous coronary bypass or valve operations, or both. Mean left ventricular ejection fraction was 30% +/- 14%, cardiac index was 2.4 +/- 0.9 L/m2, and systolic pulmonary artery pressure was 41 +/- 14 mm Hg. Under general anesthesia, the nonthoracotomy lead was introduced through the left subclavian vein. The subcutaneous patch and generator were placed posteriorly on the serratus muscle and left upper quadrant, respectively. The length of the procedure was 116 +/- 44 minutes and the mean number of defibrillation shocks for a successful implant was 8 +/- 4. Eighty-five patients (77%) had successful implantations. Failures were due to high defibrillation threshold (n = 23) and inability to place a right ventricular lead (n = 2). Predictors of failure included preoperative antiarrhythmic drugs and cardiac index of 1.8 +/- 4 L/m2 or less (p = 0.004). Three patients (2.7%) died after the operation of heart failure (n = 2) and chronic heart transplant rejection (n = 1). Complications included lead migration or dislodgment (n = 8), infection (n = 1), and hematoma (n = 3). In summary, the nonthoracotomy lead system may provide an alternative in patients undergoing cardioverter-defibrillator implantation.

Aged↗
PubMed1990

Culture of human hepatocytes from small surgical liver biopsies. Biochemical characterization and comparison with in vivo.

High yields of human hepatocytes (up to 23 X 10(6) viable cells/g) were obtained from small surgical liver biopsies (1 to 3 g) by a two-step collagenase microperfusion method. Cell viability was about 95%, attachment efficiency of hepatocytes seeded on fibronectin-coated plates was 80% within 1 h after plating, and cells survived for about 2 wk in serum-free Ham's F12 containing 0.2% bovine serum albumin, 10(-8) M insulin, and 10(-8) M dexamethasone. To evaluate the metabolism of human hepatocytes in serum-free conditions, we measured their most characteristic biochemical functions and compared them to those reported for human liver. After 24 h in culture, glycogen content was 1250 +/- 177 nmol glucose/mg cell protein and remained stable for several days. Gluconeogenesis from lactate in hormone-free media was (3.50 +/- 0.17 nmol glucose.mg-1.min-1) similar to that reported for human liver. Insulin at 10(-8) M activated glycolysis (X1.40) and glycogenesis (X1.34), and glucagon at 10(-9) M stimulated gluconeogenesis (X1.35) and glycogenolysis (X2.18). Human hepatocytes synthesized albumin, transferrin, fibrinogen, alpha 1-antitrypsin, alpha 1-antichymotrypsin, alpha 1-acid glycoprotein, haptoglobin, alpha 2-macroglobulin, and plasma fibronectin and excreted them to the culture medium. Maximum protein synthesis was stimulated by 10(-9) M dexamethasone. Basal urea synthesis oscillated between 2.5 and 3.5 nmol.mg-1 cell protein.min-1, about 5 times the value estimated for human liver. Cytochrome P-450 decreased in culture but it was still 20% of freshly isolated hepatocytes by Day 5 in culture. In addition, ethoxycumarin-O-deethylase and aryl hydrocarbon hydroxylase could be induced in vitro by treatment with methyl cholanthrene. Glutathione levels were similar to those reported for human liver (35 nmol.mg-1). The results of our work show that adult human hepatocytes obtained from small surgical biopsies and cultured in chemically defined conditions express their most important metabolic functions to an extent that is similar to that reported for adult human liver.

Biopsy↗
PubMed1990

Hemodynamic compromise associated with air trapping following coronary artery bypass surgery.

Cardiovascular collapse due to pulmonary hyperinflation was noted in a patient with chronic obstructive pulmonary disease following median sternotomy for cardiac surgery. Treatment included bronchodilator therapy to reduce airway obstruction, limitation of minute ventilation, and increasing time available for exhalation. High inspiratory flow rates and expiratory retard may be beneficial.

Acute Disease↗