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Biomedical subjects

R W Emery

Publications and source records attributed to R W Emery.

At least 91 records · Page 5Linked to original sources
PubMed1986

The cardiac donor: a six-year experience.

From March 1, 1979, to March 1, 1985, the University of Arizona received 223 cardiac donor referrals. Sixty-two were accepted: 15 local, 23 regional (less than 370 km or 200 nautical miles), and 24 distant (370 to 1556 km or 200 to 840 nautical miles). Thirty-eight donor deaths were due to motor vehicle accidents, 10 to gunshot wounds, 6 to cerebral disease, and 8 to other closed-head lesions. The mean time from injury to brain death was 65 +/- 5 hours (+/- standard error of the mean [SEM]) and from brain death to organ donation, 12 +/- 3 hours. The mean ischemic time for the donor hearts ranged from 30 to 233 minutes (mean +/- SEM, 128 +/- 7 minutes). Fifty patients, otherwise acceptable, were refused as cardiac donors because an ABO-compatible recipient was not available. Two regionally procured hearts failed at operation, 1 because of unrecognized donor sepsis and 1 from a patient on large-dose inotropic support. Although there was no difference in myocardial function, median survival with follow-up through June 30, 1985, of patients receiving locally, regionally, and distantly procured organs was 59 months, 18 months, and 21 months, respectively. Cumulative proportion 1-year survival was 93%, 56%, and 61%, respectively. The 2-year survival was 85% for patients given locally procured hearts, 43% for those with regionally procured hearts, and 38% for those with a heart from a distant donor. Survival curves showed significantly longer survival for locally procured organs than regionally or distantly procured organs (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Cardiac transplantation in patients over 50 years of age.

Sixty-two patients underwent cardiac transplantation at the University of Arizona from March 1979 to March 1985. Thirteen patients (11 men and 2 women) were over 50 years of age at the time of transplantation and 49 were under the age of 50. The mean age (+/- SEM) of the patients over 50 was 53 +/- 1 years. Eight of these patients were treated with conventional immunosuppressive therapy (azathioprine, prednisone and rabbit antithymocyte globulin) and five, beginning in January 1983, were treated with cyclosporine, prednisone and rabbit antithymocyte globulin. Early mortality (0 to 90 days) was 16% in the group over 50 versus 18% for those under 50. The late mortality (greater than 90 days) was 36 and 33%, respectively. In both groups, rejection and infection were the principal causes of death. The incidence of infection was 1.9 +/- 0.5 episodes per patient in those patients over 50 and 1.9 +/- 0.4 in those under 50. The incidence of rejection was 1.3 episodes per patient-year in patients over 50 and 1.7 episodes per patient-year in those under 50. Actuarial survival at 1 year was 72 +/- 14% in the group over 50 and 66 +/- 7% in the group under 50 years of age. These data indicate that the results of cardiac transplantation for patients over 50 do not differ significantly from those for patients under 50. Therefore, it is concluded that a rigidly defined age criterion for cardiac transplant recipients is not acceptable. Each potential recipient must be evaluated in terms of individual risk and benefit from the procedure.

Age Factors↗
PubMed1986

Reflex hypotension due to regional activation of left ventricular mechanoreceptors to explain the hypotension noted in clinical myocardial ischaemia or reperfusion.

To determine if regional increases in myocardial contractility, as may occur clinically in angina pectoris, myocardial infarction, or coronary thrombolysis, can initiate the reflex hypotension that sometimes accompanies these conditions, regional injections of positive inotropic agents were made into 32(3)% of the left ventricular myocardium in seven pneumonectomised dogs on total cardiac bypass. The coronary and systemic circulations were isolated and perfused separately. The systemic circulation was perfused at a constant rate so that changes in systemic pressure reflected changes in resistance. Regional injections of doses from 0.001 to 1.0 micrograms noradrenaline in a 0.1 ml volume appreciably increased regional contractility, detected visually and by strain gauge arches, whereas global contractility (left ventricular peak dP/dt) was increased much less. This caused a fall in the systemic pressure (resistance) of 14(2)% below the control value of 78(5)mm Hg, at the largest dose. The decreases in resistance were abolished by bilateral vagotomy, proving their reflex nature. The smaller (0.0001-0.01 micrograms) doses of noradrenaline and the smallest (0.25 micrograms) dose of veratridine increased regional contractility almost without increasing global contractility, indicating that the increase in regional contractility was the major cause of the reflex decrease in systemic resistance. In one animal a decrease in contractility in a control myocardial region occurred simultaneously with the experimentally produced increase in regional left ventricular contractility. This decrease may be analogous to the increase in contractility in the non-ischaemic left ventricular myocardium that occurs simultaneously with the decrease in contractility in the ischaemic region in clinical or experimental myocardial infarction. Left ventricular mechanoreceptors in the region with increased contractility probably initiate the reflex hypotension that sometimes occurs in both circumstances. Thus in angina pectoris or acute myocardial infarction the reflex hypotension probably originates in the hyperactive non-ischaemic myocardial region, whereas in coronary arterial thrombolysis it probably originates in the newly reperfused, formerly ischaemic, region.

Animals↗
PubMed1986

Thromboembolic complications of the Jarvik-7 total artificial heart: case report.

The Jarvik-7 total artificial heart (TAH) has now been implanted in seven patients, with four (57%) suffering cerebral embolic events. Functional recovery in two patients was impaired by subsequent intracranial hemorrhage from anticoagulant therapy. The findings of a Jarvik-7 TAH explanted following a cerebral embolus are reported here. Thrombotic deposition was seen in the inner crevice formed between the two components of the aortic quick connector. In addition, deposition was seen around all four valves in the crevice formed between the valve ring and the plastic valve housing. On the atrioventricular valves, the deposition in this crevice was most severe on the outflow surface adjacent to the minor flow orifice. On the pulmonic valve, deposition was seen around the entire circumference of both the inflow and the outflow crevices. No thrombi were seen on the diaphragm, the diaphragm-housing junction, or the housing of the left ventricle. Hypercoagulability of the patient's blood gradually developed during implant, reaching a maximum on the evening before the clinical embolus. Increasing resistance to heparin was also demonstrated by in vitro testing.

Adult↗
PubMed1986

Cardiac transplant patient at one year. Cyclosporine vs conventional immunosuppression.

From March 1, 1979 thru September 30, 1984 we performed 56 cardiac transplants (Tx). The first 32 patients received conventional immunosuppression therapy consisting of azathioprine/prednisone (I/P), while the subsequent 24 patients received cyclosporine/prednisone (C/P). Twenty-one of 32 I/P patients ages 39 +/- 3 years (SEM), and 16 of 24 eligible C/P patients ages 36 +/- 3 years, survived one year with follow-up through September 30, 1985. The one year post-transplant course of these 37 patients was evaluated by chart review. While donor ages are similar, ischemic time was shorter in the conventionally treated patients. The initial hospital stay for I/P vs C/P was 67 +/- 6 vs 33 +/- 3 days (p less than .05), at a total cost of $49,900 +/- $5,800 vs $53,800 +/- $10,000. During the first year following transplantation, the I/P patients required an additional 34 +/- 7 days of hospitalization, while C/P patients required 16 +/- 10 days. Over the first year, the number of infections and rejections differed at 2.8 +/- 0.6 per I/P patient vs 1.2 +/- 0.3 per C/P patient, and 2.5 +/- 0.4 per patient vs 1.5 +/- 0.3 per patient respectively (p less than .05). Renal function test results were better in the I/P group. Results of cardiac catheterization performed at one year were similar except for cardiac index and stroke volume index, both being higher in the C/P group. Coronary anatomy was considered normal in all. These data indicate that while overall survival is similar, a shortened post-transplant hospital course with fewer necessary hospitalizations, rejection episodes and infection episodes characterizes the first year in survivors receiving C/P immunosuppression. While both groups had multiple hemo-dynamic abnormalities as compared to normal subjects, cardiac index and stroke volume index were improved in the C/P group. Therapy with C/P represents an advance in immunosuppression for cardiac transplantation as compared to I/P; however, decreased renal function and diastolic hypertension were problems in the C/P group.

Arizona↗
PubMed1986

Interim cardiac replacement with a mechanical heart: staged cardiac transplantation.

Lack of donor heart availability complicates the management of terminally ill patients who are candidates for cardiac replacement. The total artificial heart has been used as a bridge to transplantation in three patients with terminal cardiomyopathy. Acute allograft rejection and the lack of another donor heart prompted us to use the mechanical heart as a bridge to re-transplantation in a 33-year-old man. The cardiac prosthesis functioned well for 11 hours, when a second transplantation was performed, but the patient died of right heart failure 48 hours after the second transplantation. Critical factors in such cases include (1) a prompt decision to proceed with cardiac replacement; (2) avoidance of long periods of cardiopulmonary bypass; (3) prosthetic device availability; and (4) surgical team preparedness, with technical expertise in transplantation, allograft explantation, and total artificial heart implantation/explantation, with re-transplantation.

Journal Article↗
PubMed1986

Cyclosporine: an immunosuppressive panacea?

Between March 29, 1979, and March 1, 1985, 62 heart transplants were done in 61 patients at the University Medical Center, University of Arizona. There were two treatment groups with nearly equal numbers in each; conventional immunosuppression (1979 to 1982) and cyclosporine (1982 to the present). Comparison of actuarial survival, number of rejection episodes, number of fatal rejection episodes, number of infections, and number of "other complications" failed to reveal any significant difference between the two groups. The cyclosporine-treated patients had a documented increase in blood urea nitrogen and serum creatinine accompanied by an increase in diastolic blood pressure. The length of hospital stay of the cyclosporine group was approximately one half of that of the conventionally treated patients, and they required fewer rehospitalizations. The cost for initial hospitalization was not significantly different between the two groups. Therefore, in 1979 dollars, the cost for cyclosporine-treated patients has decreased. This difference in cost was only minimally diminished by the difference in expenditure for outpatient pharmaceuticals, which was four times higher in the cyclosporine group. We believe that cyclosporine is a potent immunosuppressive agent but that it has toxic, possibly irreversible effects on the kidney. In view of the minimal differences that we were able to demonstrate in survival rejection and infection, it seems prudent to reduce or modify present doses of cyclosporine in an attempt to avoid irreversible renal damage.

Actuarial Analysis↗
PubMed1985

Heart transplantation in Arizona.

From January 1, 1979 through October 31, 1984, 58 heart transplantations have been performed in 57 patients. Conventional immunosuppression was utilized in the first 32 patients. Since January 1, 1983 cyclosporine and a low dose of prednisone have been the immunosuppressive agents of choice. The annual survival rates were 75% in 1979, 67% in 1980, 75% in 1981, 57% in 1982 and 60% in 1983. Patients whose age ranged from 50 to 57 years had similar survival to the younger recipients. Early deaths resulted from infection in 3 patients, acute rejection in 4, acute failure of the donor heart in 2 and renal failure in 2. Late deaths resulted from infection in 5 recipients, acute rejection in 2, chronic rejection in 4, arrhythmia in l and lymphoma in l. Of 31 patients alive, three months to five years after the operation, 28 are NYHA Class I or II. Heart transplantation is thus an effective therapy for selected patients.

Adolescent↗
PubMed1984

Neonatal pneumopericardium: a surgical emergency.

Pneumopericardium, a complication of ventilatory management of neonatal respiratory distress syndrome, may result in cardiac tamponade. Pneumopericardium occurred in 47 premature infants (mean birth weight, 1,894 gm) at the University of Minnesota Hospital between July, 1972, and January, 1981. At the onset of pneumopericardium, 44 of 46 intubated patients were on positive end-expiratory pressure (PEEP) and 1 patient was ventilated using a mask. Five infants were asymptomatic, while 42 were seen with sudden hypotension, bradycardia, and hypoxia an average of 57 hours (range, 1 to 312 hours) after the commencement of ventilatory support. Pneumothorax (38 instances), pneumomediastinum (21), pulmonary interstitial emphysema (29), pneumoperitoneum (6), or a combination of these conditions was noted prior to or simultaneously with pneumopericardium in 46 infants. Pneumopericardium was not treated in 14 patients, 10 of whom were symptomatic and 4 asymptomatic; there were 5 deaths in this group. The group of 33 infants treated for this complication underwent either pericardial aspiration (2 patients), aspiration followed by pericardial tube placement (12 patients), or pericardial tube placement alone (19 patients). All 33 patients who underwent treatment had resolution of symptoms, but pneumopericardium recurred in 13 with 5 deaths. Causes of recurrence were tube or aspiration failure in 10 infants and tube removal prior to cessation of PEEP in the other 3. There were five complications related to tube placement, resulting in 2 deaths due to myocardial laceration following percutaneous insertion. Of 35 neonates surviving pneumopericardium, 12 were discharged from the hospital and 23 died of complications of respiratory distress syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)

Drainage↗
PubMed1983

Coexistent carotid and coronary artery disease. Surgical management.

We performed simultaneous coronary artery bypass grafting (CABG) and carotid endarterectomy (CE) in 42 patients (average age, 61 years). Twenty-nine patients had preoperative transient ischemic attacks. Carotid arteriography showed stenosis (greater than 70%) in 38 subjects and extensive ulcerated lesions in two, and two emergency patients were not studied. Carotid artery dissection and sternotomy were simultaneously performed and the patients were cannulated for cardiopulmonary bypass (CPB). We undertook CE (22 left and 24 right) using EEG monitoring prior to CPB in all but one patient. The average carotid occlusion time was 25 minutes without a shunt in 23 patients and 5.5 minutes with a shunt in 19 patients. After CE, CABG was performed with an average aortic clamp time of 39 minutes and an average CPB time of 87 minutes. The operative mortality was 5% (2/42). There were no strokes or perioperative myocardial infarctions. Neurologic morbidity consisted of postoperative headache in one patient, transient upper-extremity weakness in two patients, and transient facial weakness in one patient. The average length of postoperative hospitalization was ten days. Currently, patients with symptomatic coronary artery disease and concomitant carotid bruits with positive noninvasive testing and arteriography should have simultaneous repair of these lesions.

Aged↗
PubMed1981

Clinical and hemodynamic results with the St. Jude Medical cardiac valve prosthesis. A three-year experience.

Two hundred thirty-two consecutive patients (October 3, 1977, through December, 31, 1980) underwent aortic (AVR), mitral (MVR), or double (DVR) valve replacement with the St. Jude Medical (SJM) prosthesis. Operative mortality for the entire group was 7.3%. There was 100% follow-up. Warfarin (Coumadin) anticoagulation was recommended for all patients. There were no cases of mechanical failure. The incidence of thromboembolism was 0.6/1,000 patient-months for those with AVR, 3/1,000 patient-months for those with MVR, and 0% for those with DVR. Thrombosis of a prosthesis occurred in two patients with DVR. Clinically significant hemolysis occurred in three patients with paravalvar leaks following MVR. Late postoperative prosthetic infection has not occurred. Postoperative catheterization studies in 33 patients revealed no transvalvular gradient at rest in 21 patients. The remainder of the patients catheterizd had low transvalvular gradients. There was a minimal increase in transvalvular gradient with exercise. The SJM cardiac valve is a viable alternative in the surgical therapy of valvular heart disease.

Adolescent↗
PubMed1980

Effect of heart rate on myocardial blood flow in dogs with left ventricular hypertrophy.

Because of the previous suggestion that subendocardial perfusion may be inadequate in the hypertrophied heart, this study was carried out to examine the response of transmural myocardial blood flow to pacing induced tachycardia in dogs with chronic left ventricular hypertrophy. Myocardial hypertrophy, produced by banding the ascending aorta of puppies at 5-6 wk of age, resulted in an 87% average increase in relative left ventricular mass compared with the control dogs. Myocardial blood flow was examined during ventricular pacing at heart rates of 100, 200, and 250 beats/min using radionuclide-labeled microspheres. Mean blood flow per unit myocardial mass was similar in the two groups of dogs at a heart rate of 100 beats/min and increased regularly during pacing in both groups of animals. Increasing heart rates did not change the transmural pattern of myocardial blood flow in the normal dogs, but in the animals with left ventricular hypertrophy pacing at 250 beats/min resulted in a significant redistribution of perfusion away from the subendocardium, with the ratio of subendocardial/subepicardial blood flow falling from 1.03 +/- 0.08 at 100 beats/min to 0.83 +/0 0.06 at 250 beats/min (P < 0.01). This redistribution of blood flow away from the subendocardium was especially marked in the regions encompassing the papillary muscles and the intervening left ventricular lateral wall.

Animals↗