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Biomedical subjects

T J Ryan

Publications and source records attributed to T J Ryan.

At least 325 records · Page 18Linked to original sources
PubMed1984

Supernatants from cultured human epidermal keratinocytes stimulate angiogenesis.

Conditioned media from three different strains of human epidermal keratinocytes in culture were assayed on the chorioallantoic membrane of the chick embryo. Vascular responses were examined 4 days later stereo-microscopically and compared with controls--unconditioned medium and medium incubated with 3T3 cells. Specimens were also collected after 1, 2, 3 and 4 days for serial histological examination. Media from all three strains of keratinocytes stimulated statistically significant vascular growth relative to controls. Leukocytic infiltration was not demonstrated histologically at any time. In addition, quantitation of ectodermal epithelial hyperplasia in experimental groups did not reveal any significant difference when compared with controls. These results have demonstrated that epidermis may directly encourage vascular growth in the absence of significant inflammation.

Allantois↗
PubMed1984

Increased risk of severe protamine reactions in NPH insulin-dependent diabetics undergoing cardiac catheterization.

Protamine is widely used for reversing systemic heparinization after cardiac catheterization. Although rare, major reactions to protamine that simulate anaphylaxis occasionally occur and have previously been associated only with an allergic reaction to fish. Because neutral protamine Hagedorn (NPH) insulin includes protamine, it might be anticipated that NPH insulin-dependent diabetic patients would develop sensitivity to protamine. Of 866 consecutive patients undergoing cardiac catheterization over a 20 month period, 651 received protamine for reversal of heparinization. Of these, 8.5% (56/651) were diabetics and 2.3% (15/651) were NPH insulin-dependent diabetics. During this period seven patients were observed immediately after administration of protamine to have major adverse reactions that required the administration of catecholamines. One death ensued. Of the seven major reactions, four occurred in NPH insulin-dependent diabetics and one occurred in a patient with an allergy to fish. The incidence of major protamine reactions was 27% (4/15) in the NPH insulin-dependent diabetics vs 0.5% (3/636) in those with no history of NPH insulin use (p less than .001). This represents a 50-fold increased risk of a major reaction to protamine if the patient was receiving NPH insulin. Accordingly, we recommend that diabetics on NPH insulin and patients with allergies to fish undergo cardiac catheterization without the use of protamine or, when necessary, that protamine be administered cautiously in anticipation of a major adverse reaction.

Anaphylaxis↗
PubMed1984

Detrimental effect of perioperative myocardial infarction on late survival after coronary artery bypass. Report from the Coronary Artery Surgery Study--CASS.

The influence of perioperative myocardial infarction on late survival after coronary artery bypass grafting was reviewed in 9,777 patients who underwent operation between 1974 and 1979. Definite or probable perioperative myocardial infarction was diagnosed in 561 patients (5.7%). The incidence decreased from 6.6% in 1974 to 4.1% in 1979 (p less than 0.005). Actuarial survival, including hospital deaths, at 1, 3, and 5 years was significantly greater in patients without infarction than in patients with infarction (96%, 94%, and 90% versus 78%, 74%, and 69%; p less than 0.0001). The difference persisted among patients dismissed from the hospital. Reduction in late survival among patients with perioperative infarction was due to the poor outcome of those who had complications (5 year survival rates 40% overall and 73% for patients dismissed from the hospital). Multivariate analysis identified perioperative myocardial infarction as an important independent predictor of late survival after bypass grafting; it was surpassed only by left ventricular function (wall motion score), age, and number of associated medical diseases.

Coronary Artery Bypass↗
PubMed1984

A tricky trio.

Explore the source record for details and available documents.

Adult↗
PubMed1984

The value of preoperative exercise testing in predicting long-term survival in patients undergoing aortocoronary bypass surgery.

To determine whether preoperative exercise testing adds important independent prognostic information in patients undergoing coronary bypass surgery, 35 variables were analyzed in 1241 patients enrolled in the Coronary Artery Surgery Study registry. All patients underwent a treadmill exercise test before bypass surgery and were followed for up to 7 years. Survival in this surgical cohort was 90.6% (1124 of 1241). Multivariate stepwise dicriminant analysis identified the left ventricular score and the final exercise stage achieved as the two most important (p less than .001) independent predictors of postoperative survival. In a subgroup of 416 patients with three-vessel coronary disease and preserved left ventricular function, the probability of postoperative survival at 7 years ranged from 95% for those patients able to exercise to stage 4 to 83% for those whose ability was limited to stage 1 of exercise. Thus, the preoperative exercise test, by assessing the functional capacity of the cardiovascular system, is an important independent predictor of postoperative survival.

Coronary Angiography↗
PubMed1983

Efficacy and safety of verapamil in patients with angina pectoris after 1 year of continuous, high-dose therapy.

The long-term efficacy and safety of high-dose verapamil therapy (480 mg/day) was assessed in 26 patients with chronic stable angina pectoris during a 3-phase protocol: Phase 1--an initial, 6-week placebo-controlled, double-blind crossover assessment; Phase 2--an open label, 1-year follow-up; and Phase 3--a final drug withdrawal and rechallenge 10-week study. Three patients withdrew during Phase 2 (1 had hepatitis and 2 underwent coronary bypass surgery). Adverse effects during Phase 2 were mild, consisting of constipation (6 patients) and prolongation of the P-R interval (5 patients); however, no patient required alteration of the 480 mg/day dosage. At the end of Phase 2, 10 patients underwent the Phase 3 study, commencing with a 2-week period in which verapamil was either tapered gradually or abruptly discontinued. This was followed by an 8-week double-blind, placebo-controlled crossover rechallenge study with verapamil. The clinical and exercise responses to verapamil compared with placebo were similar during the Phase 3 protocol and the initial Phase 1 study (treadmill time increased by 55% and anginal attacks per week decreased by 63% during Phase 3, compared with a 28% increase and a 42% decrease, respectively, during Phase 1, p = not significant [NS]). Withdrawal of verapamil produced a similar return of anginal symptoms whether the drug was abruptly discontinued or its administration tapered. No patient had unstable angina pectoris or acute myocardial infarction. These investigations demonstrate that verapamil is safe and effective when evaluated after 1 year of continuous therapy using a dosage of 480 mg/day. There is no evidence of drug tachyphylaxis, nor does verapamil appear to cause an abrupt withdrawal syndrome in patients with chronic stable angina pectoris.

Adult↗
PubMed1983

Cardiokymography during exercise testing: a new device for the detection of coronary artery disease and left ventricular wall motion abnormalities.

The cardiokymograph (CKG) is a device that has been shown to reflect left ventricular (LV) wall motion abnormalities. Its accuracy in detecting coronary artery disease (CAD) during treadmill exercise testing was assessed in 204 consecutive patients undergoing coronary arteriography. Of the 188 patients with a technically adequate CKG, 146 (78%) had significant CAD. The sensitivity and specificity were similar for both the exercise electrocardiogram (ECG) (66% and 86%, respectively) and the exercise CKG (73% and 95%, respectively). An abnormal exercise CKG was significantly more common in patients with 3-vessel CAD than in those with 1-vessel disease (97% versus 52%, respectively; p less than 0.001) and in patients with left anterior descending disease than in those without (85% versus 26%, respectively; p less than 0.001). Seventy patients showed both an abnormal exercise ECG and CKG; all had CAD and 86% had multivessel CAD. Forty-eight patients demonstrated a normal exercise ECG and CKG; 29% had CAD but only 6% had multivessel CAD. Among 55 patients who had simultaneous exercise radionuclide ventriculography, new septal or apical wall motion abnormalities were found in 79% (23 of 29) of patients with an abnormal CKG compared with 19% (5 of 26) of patients with a normal CKG (p less than 0.001). Thus, the CKG during exercise testing accurately reflects LV wall motion abnormalities and can be used to improve the diagnostic accuracy of exercise testing as an additional marker of myocardial ischemia.

Adult↗
PubMed1983

Early experience with popliteal to infrapopliteal bypass for limb salvage.

In an attempt to improve graft patency and limb salvage in patients with isolated tibial vessel and/or popliteal-tibial vessel occlusive disease, bypass grafts from the popliteal or distal superficial femoral artery to infrapopliteal arteries were used in patients requiring bypass for limb salvage. During a 2 1/2-year period, 23 patients with patent axial vessels and hemodynamically normal inflow to the level of the knee underwent such bypasses. Cumulative graft patency and limb salvage rates at 31 months were 84% and 70%, respectively. Five of the six patients who required below-knee amputation did so because of progressive gangrene in the presence of a patent bypass. Short bypasses between the popliteal and infrapopliteal arteries can significantly contribute to limb salvage in patients with tibial vessel occlusive disease and may be particularly useful in patients with saphenous veins too short for longer bypasses.

Adult↗
PubMed1983

The treatment of cerebral ischemia by external carotid artery revascularization.

Thirteen patients with internal carotid artery occlusion and symptomatic external carotid artery stenosis underwent external carotid artery revascularization by means of endarterectomy (n = 10) or subclavian artery--external carotid artery bypass (n = 3). All patients but one were followed up, for five to 46 months (mean, 20 months). There were no operative deaths or complications and no late strokes. One patient (7.7%) required early extracranial-intracranial (EC-IC) bypass for failure of the external carotid artery endarterectomy to relieve the initial symptoms. All remaining patients were completely (n = 9) or partially (n = 2) relieved of symptoms, and EC-IC bypass was not required. There were no criteria identified by either oculopneumoplethysmography or angiography that could reliably predict the need for subsequent EC-IC bypass. Ninety-two percent of the patients were adequately treated with external carotid artery revascularization alone, suggesting that subsequent EC-IC bypass is seldom required in patients with ipsilateral internal carotid artery occlusion and external carotid artery stenosis.

Aged↗
PubMed1983

Physical factors and angiogenesis.

Angiogenesis consists of migration and mitosis of blood vessels and lymphatic endothelium. The control of angiogenesis is multifactorial, being determined by physical as well as chemical factors. The physical factors include contact, binding, scaffolds and barriers, attachment, spreading, lining and even phagocytosis. The vascular pattern in the skin suggests that epithelium is a principal influence on angiogenesis and that it may guide or obstruct the growth of its blood supply, using fibrin, collagen, elastin and ground substance as a means of exerting control. The hamster cheek pouch and the chorioallantoic membrane have been used to demonstrate that epithelium exerts both chemical and physical effects. There is a need for further investigation of mechanisms underlying the conversion of physical factors into chemical signals. They probably include the release of proteases or their inhibitors during the distortion of fibrillar material.

Animals↗
PubMed1983

Prognostic assessment of patients with coronary artery disease by exercise testing.

To assess whether exercise testing could help predict cardiac mortality, we analyzed 14 exercise and 10 clinical variables in 292 patients treated medically, who underwent treadmill exercise testing and cardiac catheterization and were followed annually for a mean of 2.5 years. None of the individual variables could accurately predict subsequent cardiac mortality with predictive values ranging from 6% to 44%. Combinations of variables were then analyzed in the subset of 113 patients with multivessel coronary disease. A high-risk subgroup (n = 59) consisting of patients with either severe exercise ischemia (greater than or equal to 2 mm ST depression lasting greater than or equal to 5 minutes involving greater than or equal to 3 leads) or left ventricular dysfunction (treadmill time less than or equal to 3 minutes, S3 gallop, or cardiac enlargement) had a mortality of 20%; this was significantly greater (p less than 0.01) than a low-risk subgroup (n = 54) with neither severe exercise ischemia nor left ventricular dysfunction whose mortality was 2%. We conclude that combining clinical and exercise variables to distinguish high- and low-risk subgroups of patients with similar coronary anatomy is useful in predicting cardiac mortality.

Adult↗
PubMed1983

Atropine-induced cardioacceleration in patients on chronic propranolol therapy: comparison with the positive chronotropic effect of isometric exercise.

The hemodynamic effects of intravenous atropine administration were examined in 24 patients on chronic propranolol therapy. In the first 13 patients the safety of atropine administration was tested by giving the drug in small increments to a total dose of either 1.2 mg (five patients) or 1.7 mg (eight patients). The heart rate after atropine administration in these patients varied between 57 and 82 bpm and no adverse effects were noted. The other 11 patients received 1.2 mg atropine intravenously with hemodynamic measurements obtained prior to and 3 minutes after administration of the drug. Heart rate increased from 57.5 +/- 8.7 to 72.8 +/- 13.9 bpm, mean pulmonary arterial and left ventricular end-diastolic pressure declined, and cardiac index increased. Total systemic resistance decreased in most of the patients. Isometric exercise performed prior to atropine administration in the same 11 patients accelerated heart rate from 57.4 +/- 8.6 to 68.4 +/- 10.8 bpm. A close correlation, r = 0.909, was demonstrated between the postatropine heart rate and the rate during isometric exercise. It is concluded that atropine in a dose of 1.2 to 1.7 mg may be administered safely in patients on chronic propranolol therapy. Isometric exercise may be useful in unmasking vagal tone in beta-blocked patients.

Adult↗
PubMed1983

Effects of nitroglycerin on isometric exercise.

Eight patients with ischemic heart disease performed isometric handgrip of five minutes' duration at 30% of their maximum voluntary contraction, before and after administration of 0.4 mg sublingual nitroglycerin (NTG). Although isometric exercise resulted in similar rise of left ventricular systolic pressure (LVSP) before and after NTG, the level of LVSP during the post NTG effort was lower. Heart rate, cardiac index, stroke index, left ventricular stroke work index, and systemic resistance were not different during the pre- and post NTG exercise. Left ventricular end-diastolic pressure rose to a significantly lower level (18.3 +/- 14.4 mm Hg) during the post NTG handgrip than during the pre NTG effort (31.4 +/- 17.6 mm Hg, P less than 0.005). It is concluded that NTG reduces preload and afterload both at rest and during isometric exercise and improves left ventricular performance during isometric exercise.

Blood Pressure↗