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Biomedical subjects

E H Austin

Publications and source records attributed to E H Austin.

52 records · Page 3Linked to original sources
PubMed1985

Aneurysm of aberrant subclavian artery with a review of the literature.

Aneurysms arising in an aberrant subclavian artery are rare but constitute a potentially lethal condition that can be treated successfully when appropriately identified. Virtually all patients have a superior mediastinal mass that may be asymptomatic, but usually patients have symptoms of dysphagia, chest pain, or shortness of breath. An accurate diagnosis can now be made noninvasively with computerized tomography. The presence of an aneurysm of an anomalous subclavian artery is an indication for surgical resection. Resection of the aneurysm may be approached through either a right or left thoracotomy. Reestablishment of continuity of flow to the right subclavian artery decreases the risk of ischemia of the extremities and prevents development of the subclavian steal syndrome. Reestablishment of flow to the right subclavian artery is more easily performed through a right thoracotomy incision but this approach limits control of the aorta at a possibly treacherous connection between aorta and aneurysm. In such circumstances a preliminary extra-anatomic reconstitution of flow to the right subclavian artery followed by a left thoracotomy may be preferable. A 67-year-old woman is described who had resection and grafting of an aneurysm in an aberrant right subclavian artery together with a review of the literature and a discussion of problems in the management of patients with this condition.

Adult↗
PubMed1983

Relation between QRS changes and left ventricular function after coronary artery bypass grafting.

Preoperative and serial postoperative electrocardiograms (ECGs) were reviewed in 104 patients undergoing rest and exercise radionuclide angiocardiography before and 1 to 12 months after coronary artery bypass grafting (CABG). Five patient groups were defined by ECG findings before and after CABG: Group I--normal ECG before and no ECG change after CABG; Group II--prior myocardial infarction by ECG before but no QRS change after CABG; Group III--all patients with a minor QRS change (less than 0.04-second Q wave, loss of R-wave amplitude) after CABG; Group IV--all patients with a major QRS change (greater than or equal to 0.04-second Q wave) after CABG; Group V--all patients without new Q waves or loss of R-wave amplitude but with a major QRS change (conduction disturbance) after CABG. Mean resting ejection fraction changed little after CABG in all groups, although the 0.03 increase in Group I was significant (p less than 0.05). Group IV had the largest decrease in resting ejection fraction after CABG (0.04), but this was not statistically significant. Mean exercise ejection fraction increased significantly (p less than 0.0001) in Groups I, II and III but not in Groups IV and V. QRS changes do not consistently reflect impairment of left ventricular (LV) function after CABG.

Angina Pectoris↗
PubMed1983

Radionuclide left ventricular volume curves in angiographically proved normal subjects and patients with three-vessel coronary disease.

To determine the diagnostic value of measurements obtained from radionuclide left ventricular volume curves, we compared 12 patients with normal coronary arteries (NL) to 12 patients with three-vessel coronary artery disease (3V CAD). Maximum and mean rates of ejection and filling, times of maximum ejection and filling, durations of systole and diastole, and percentages of ejection and filling during each third were measured at rest and during exercise. The only group differences at rest were a 39 msec (p = 0.002) delay in the time of maximal filling and a 6% (p = 0.04) decrease in first third filling fraction in the 3V CAD patients. The overlap in values for these two parameters, however, did not allow good separation of the patients into NL and 3V CAD groups. During exercise, maximal and mean rates of ejection and filling were significantly lower in the 3V CAD group, but these measurements did not improve on the discriminative value of heart rate and ejection fraction alone. Thus, in both the resting and exercise states, measurements of instantaneous changes in left ventricular volume added little diagnostic information.

Aged↗
PubMed1983

Thymoma following transcervical thymectomy for myasthenia gravis.

A superior mediastinal thymoma was found in a patient two years following a transcervical thymectomy for myasthenia gravis. This case report illustrates another potential complication of incomplete thymectomy that may occur with the transcervical approach.

Female↗
PubMed1983

Early assessment of rest and exercise left ventricular function following coronary artery surgery.

Radionuclide assessment of rest and exercise left ventricular function was performed in 14 patients before, eight days after, and three months after coronary artery bypass grafting (CABG). Resting function was unaltered after operation, although mild increases in heart rate and end-diastolic volume were observed on the eighth postoperative day. In contrast, exercise function was significantly improved at both postoperative time periods. Exercise ejection fraction was 0.54 +/- 0.10 before operation, 0.73 +/- 0.12 at eight days, and 0.64 +/- 0.13 at three months. Before CABG, the exercise-induced increase in stroke volume was achieved by an increase in end-diastolic volume, whereas eight days after CABG this increase was achieved by an increase in contractility (systolic blood pressure/end-systolic volume). By three months, both contractility and end-diastolic volume increased with exercise. Thus, improvement in left ventricular function during exercise can be documented as early as eight days after coronary revascularization. This change may be less pronounced after three months of convalescence, but considerable improvement in ventricular function persists compared to preoperative assessment.

Aged↗
PubMed1983

The role of radionuclide angiocardiography in the preoperative prediction of pain relief and prolonged survival following coronary artery bypass grafting.

Radionuclide angiocardiography (RNA) provides noninvasive measurements of left ventricular function during rest and exercise, which appear to reflect the magnitude of fibrosis and ischemia in patients with coronary artery disease. This investigation evaluated the usefulness of these measurements for providing prognostic information, useful in selecting therapy. The RNA study group included 278 patients with a low resting ejection fraction and coronary artery disease documented by angiography. Patients were followed for up to three years to define survival and incidence of complete pain relief. The 172 patients treated medically had less favorable survival and pain relief than the 106 surgically treated patients. In the medically treated patients, a positive RNA defined a subgroup of 113 patients, with a 20% lower 3-year survival than the 59 patients with a negative RNA. Moreover, comparison of patients receiving medical and surgical therapy following a positive RNA documented a clear improvement in both survival and pain relief for those who showed significant ischemia during exercise and subsequently underwent coronary bypass procedures. In patients with a negative RNA, medical and surgical therapy resulted in a similar survival rate and little difference in pain relief. Calculations comparing the maximal potential increase in survival and complete pain relief, using multiple criteria known to provide prognostic information, identified the exercise response on RNA as the single most important variable for selection of therapy. Therefore, the left ventricular response to exercise provides important prognostic information in patients with low resting ejection fractions, and the results of this procedure can be used to define subgroups of patients who will and will not benefit from coronary artery bypass grafting.

Cardiac Catheterization↗
PubMed1982

Prospective evaluation of radionuclide angiocardiography for the diagnosis of coronary artery disease.

This investigation assesses prospectively the accuracy of rest and exercise radionuclide angiocardiography (RNA) in detecting coronary artery disease (CAD). By retrospective analysis of 496 patients, optimal RNA criteria were determined for the presence or absence of CAD. Multivariate analysis of patients with normal coronary arteries on catheterization provided a formula to predict normal exercise ejection fraction (EF) in a given patient. The presence of CAD was indicated by 1 or more of the following RNA measurements: (1) rest EF less than 0.50, (2) exercise EF at least 0.06 less than the predicted value, (3) exercise increase in end-systolic volume greater than 20 ml, (4) exercise-induced wall motion abnormality. The absence of CAD was indicated by the absence of all 4 criteria. After applying these criteria to 221 consecutive patients, the RNA determinations were compared with the catheterization, determinations. Significant CAD was present in 71% of the patients studied. The sensitivity of the test was 0.87 and the specificity 0.54. Thus, because of its high sensitivity, RNA is of value in screening patients under consideration for cardiac catheterization. No patient with significant left main coronary narrowing and only 4 of 65 patients with 3-vessel disease were misdiagnosed. The poor specificity of the test, however, limits its overall accuracy.

Adult↗
PubMed1981

Radionuclide angiocardiography in the diagnosis of congenital heart disorders.

Radionuclide angiocardiography provides a noninvasive assessment of cardiac function and blood flow through the heart and lungs. During the past three years, this procedure has been used at the Duke University Medical Center for evaluation of 343 patients with congenital heart disorders. A review of this experience shows tat the resulting data were frequently useful in the surgical management of these patients. In patients with abnormal blood flow patterns, noninvasive imaging of blood flow was useful before and after operative correction. Radionuclide measurements of left-to-right intracardiac shunts were sufficiently accurate for use in the initial evaluation of patients with murmurs and to document the absence of shunt after operative closure of intracardiac septal defects. Moreover, measurements of right-to-left cardiac shunts were of benefit in the management of children with cyanotic heart disease. Measurements of left ventricular function obtained during rest and exercise were most useful in patients with origin of the left coronary artery from the pulmonary artery and in patients with congenital valvular insufficiency. This experience demonstrates that radionuclide angiocardiography provides important measurements of central hemodynamics and cardiac function which are useful in the management of patients with congenital heart disorders.

Adolescent↗
PubMed1981

Accuracy of diagnosis of coronary artery disease by radionuclide management of left ventricular function during rest and exercise.

Rest and exercise radionuclide angiocardiographic measurements of left ventricular function were obtained in 496 patients who underwent cardiac catheterization for chest pain. Two hundred forty-eight of these patients also had an exercise treadmill test. An ejection fraction less than 50% was the abnormality of resting left ventricular function that provided the greatest diagnostic information. In patients with normal resting left ventricular function, exercise abnormalities that were optimal for diagnosis of coronary artery disease were an injection fraction at least 6% less than predicted, an increase greater than 20 ml in end-systolic volume and the appearance of an exercise-induced wall motion abnormality. The sensitivity and specificity of the test were lower in patients who were taking propranolol at the time of study and in patients who failed to achieve an adequate exercise end point. In the 387 patients with an optimal study, the test had a sensitivity of 90% and a specificity of 58%. Radionuclide angiocardiography was more sensitive and less specific than the exercise treadmill test. The high degree of sensitivity of the radionuclide test suggests that it is most appropriately applied to patient groups with a high prevalence of disease, including those considered for cardiac catheterization.

Adult↗
PubMed1981

Effect of valve replacement for chronic mitral insufficiency on left ventricular function during rest and exercise.

In this study we measured left ventricular function at rest and during exercise before and after operation in 18 patients who underwent mitral valve replacement (MVR) for chronic mitral insufficiency. First-transit radionuclide angiocardiography was employed a week before operation and 5 to 19 months after operation to calculate left ventricular ejection fraction, volumes, output, filling, and emptying rates. Preoperatively, left ventricular ejection fraction increased from 0.56 +/- 0.09 (mean +/- S.D.) at rest to 0.62 +/- 0.11 during exercise, and this response was not altered for the group after operation. After valve replacement, there was no consistent change in end-diastolic volume (EDV), and cardiac function was not related to an alteration in filling rates of the left ventricle. After operation, the patient group achieved a maximal ventricular filling rate during exercise comparable to that measured before operation. In addition, postoperative maximal filling rates did not correlate with prosthetic valve size. These data suggest that the hemodynamic changes elicited by MVR for chronic insufficiency are primarily related to the elimination of the regurgitant flow but no attributable to alterations of the myocardium. It is suggested that limitation in exercise performance after operation may be primarily related to the functional status of the myocardium prior to operation.

Adult↗
PubMed1981

Solitary hepatic cyst and benign bile duct polyp: a heretofore unheralded association.

Solitary hepatic cysts are uncommon lesions that can produce jaundice by extrinsic compression on the extrahepatic biliary tree. In two recent cases of solitary hepatic cyst with jaundice, an intraluminal polypoid adenoma that obstructed the common hepatic duct was discovered. Concurrence of these two unusual lesions suggests that they may be associated. The importance of recognizing this association is illustrated by two case reports. In case 1, extrinsic compression by the cyst on the common hepatic duct was identified as the cause of jaundice at the initial operation. In case 2, choledocholithiasis was the initial explanation for the jaundice. In both cases, palpation and exploration of the proximal bile ducts with probes and catheters failed to discover the polyp. However, jaundice persisted postoperatively in both cases, and subsequent contrast radiography revealed an intraluminal filling defect in the common hepatic duct. In both cases, reoperation was required, and a benign bile duct polyp was discovered and excised. Thus, the presence of jaundice in a patient with a cystic hepatic mass should suggest the possibility of a concurrent bile duct polyp. Awareness of this possibility should permit recognition of such a polyp at initial operation.

Adenoma↗
PubMed1980

Effects of protein-calorie restriction on the immune response to skin allografts in the rat.

The effect of protein depletion on immune responsiveness was examined using a skin allograft model. Protein depletion was induced in adult Fischer (F344) male rats by the ad libitum provision of a 5% protein diet. Total serum protein, total body weight, total body nitrogen, and total body lipid were all markedly decreased in these rats. Skin from control-fed Brown Norway (BN) male rats was grafted to the middorsal region of control and protein-depleted F344 rats. BN skin allografts survived significantly longer on protein-depleted recipients (13.3 days) than on controls (8.5 days). Splenic lymphoid cells from skin grafted F344 rats were assayed for cytotoxicity against BN and F344 lymphoid cells in a 51Cr release assay. At effector to target ratios of 50:, 100:, and 200:1, spleen cells from control rats exhibited greater than 35% allospecific cytotoxicity 8 days after grafting. Spleen cells from protein-depleted rats exhibited no greater than 10% cytotoxicity from 6 to 15 days after grafting. A depression of cytotoxicity by protein depletion was also observed in rats immunized by i.p. injection of BN spleen cells. Heat-inactivated sera from skin grafted F344 rats were assayed against BN and F344 lymphoid cells in a complement-dependent trypan blue exclusion assay. Cytotoxic alloantibodies were measurable in both control and protein-depleted rats 9 days after grafting, but were of significantly lower titer in the protein-depleted group. The results indicate that both humoral and cell-mediated immune responses to alloantigens are impaired by protein-calorie malnutrition.

Animals↗
PubMed1979

The treatment of recurrent malignant pleural effusion.

Effective control of a recurrent malignant pleural effusion can greatly improve the quality of life of the cancer patient. At least a dozen different techniques have been advocated for controlling this common complication of malignant disease. The present review collects and examines the clinical results of all techniques designed to treat this problem. The pathophysiology and diagnostic evaluation of the effusion are also discussed. On the basis of comparisons involving effectiveness, morbidity, and convenience, we recommend intrapleurally administered tetracycline with thoracostomy drainage as the technique of choice. Instillation of a talc suspension with thoracostomy drainage is also a safe and effective technique and should be employed when tetracycline fails or is contraindicated.

Drainage↗
PubMed1978

Anaphylactoid type reactions in two patients receiving high dose intravenous methotrexate.

Two patients recieving intravenous high dose methotrexate (MTX) and intracutaneous BCG injections as adjuvant treatment for osteogenic sarcoma suffered sudden cardiovascular collapse within minutes of infusion of MTX. These cases demonstrate that anaphylactic or idiosyncratic reactions to MTX and/or contaminants in these preparations do occur and that careful patient monitoring is required.

Adolescent↗
PubMedDate not supplied

Animal model of the univentricular heart and single ventricular physiology.

The univentricular heart complexes are a fairly common and potentially lethal set of congenital cardiac anomalies. Progress in developing new therapeutics has been hampered by a lack of suitable animal models. The authors developed a stable, closed heart preparation to systematically examine potential interventions. Using neonatal piglets (3.5-6.0 kg), a 6-mm PTFE graft was anastomosed end to end to the innominate artery and end to side to the pulmonary artery. An atrial septostomy was made, using a Rashkind septostomy catheter passed transvenously. With the same catheter, the tricuspid valve was rendered incompetent. Occlusion of the right ventricular outflow tract completed a univentricular circuit. All cardiac output exited from the left ventricle, and pulmonary blood flow was maintained via the innominate artery-to-pulmonary artery shunt. Pressure transducers measured central venous (mid inferior vena cava), aortic, and pulmonary arterial pressures. Oximetric probes recorded systemic venous and arterial oxygen saturations. Transit-time flow probes measured total cardiac output and pulmonary flows. Systemic flow was calculated by subtracting pulmonary flow from total cardiac output. This model has been completed in 30 animals. Minimal pressure drops have been recorded across the innominate-to-pulmonary artery graft. Pulmonary flows up to 700 +/- 52 mL/min were seen. Total cardiac outputs are as high as 1370 +/- 88 mL/min. Mean ratios of pulmonary to systemic flow (Qp/Qs ratio) range from 1.29 +/- 0.08 to 0.41 +/- 0.09. The model allows for full continuous monitoring of systemic and pulmonary pressures and flows and for accurate characterization of the physiological effects of respiratory and pharmacological interventions. In addition, mechanical constriction of the graft may allow direct alteration of the Qp/Qs ratio, with determination of an optimum value for this ratio.

Anastomosis, Surgical↗