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Biomedical subjects

T J Ryan

Publications and source records attributed to T J Ryan.

At least 397 records · Page 22Linked to original sources
PubMed1980

Increase in R-wave amplitude during transient epicardial injury (Prinzmetal type).

An increase in QRS amplitude with S-T elevation occurs during the acute phase of myocardial infarction, coronary ligation and variant angina. Ischemic conduction delay, postulated as the cause, has not been well characterized. Six patients with transient chest pain, S-T elevation and increase in R-wave voltage also displayed concomitant shift of the frontal QRS axis toward the locus of injury. Electrocardiographic considerations suggest that regional ischemic block, not true hemiblock as has been suggested, offers the most inclusive explanation, providing previously neglected clinical confirmation of experimental observations.

Adult↗
PubMed1980

Antiarrhythmic efficacy, pharmacokinetics and clinical safety of tocainide in convalescent myocardial infarction patients.

The antiarrhythmic efficacy and pharmacokinetics of tocainide, an oral analog of lidocaine, was evaluated in 18 hospitalized convalescing myocardial infarction patients. Holter ECG tapes were recorded daily during two-day placebo therapy preceding and succeeding two days of tocainide treatment. Left ventricular function was characterized from prior or subsequent arteriographic studies (ten cases) or from radionuclide scanning (eight cases). Tocainide dosage was 17.7 +/- 4.9 SD mg/kg/day. Plasma half-time of elimination was 19.1 +/- 6.8 hours (r = 0.9). Tocainide had no significant effect on heart rate, pulse rate, or QTC intervals and did not worsen chronic heart failure, even in patients with ejection fraction < 30%. In seven of 18 patients, tocainide significantly reduced ventricular premature beat (VPB) frequency as compared to predrug and postdrug placebo periods. Drug responders averaged a 200 to 545% reduction in VPB frequency at tocainide blood levels of > 3.5 microgram/ml.

Adult↗
PubMed1980

Sequential radionuclide imaging during paracorporeal left ventricular support.

A paracorporeal left ventricular to ascending aorta assist device (LVAD) was utilized in four patients with refractory cardiogenic shock following cardiac surgery. Hemodynamic stabilization was achieved in all four patients, two of whom were subsequently discharged from the hospital and continue to do well one year later. A technique is described for obtaining radionuclide ejection fractions (EFs) during temporary LVAD interruption. The EFs appeared to be predictive of eventual unassisted ventricular function and possibly of patient survival.

Adult↗
PubMed1980

Multivariate discriminant analysis of the clinical and angiographic predictors of operative mortality from the Collaborative Study in Coronary Artery Surgery (CASS).

The Collaborative Study in Coronary Artery Surgery (CASS) is a large multi-institutional study of the medical and surgical treatment of coronary artery disease (CAD). Fifteen cooperating institutes have carried out isolated coronary artery bypass grafting (CABG) on 6,176 patients from August, 1975, through December, 1978. The operative mortality (OM) was 2.3%. In an effort to better understand the clinical and angiographic characteristics predictive of OM, we have done a multivariate discriminant analysis of variables associated with OM. Numerous clinical and angiographic variables were selected from the CASS data file and evaluated in a univariate manner for their relationship to OM. Twenty of these variables were then selected for multivariate discriminant analysis. Clinical variables of most predictive value were age, female sex, increased heart size, and congestive heart failure (CHF). Angiographic variables of importance included left ventricular wall motion abnormalities, and left main coronary disease (LMCD). The priority of operation (elective, urgent, or emergent) was also associated with OM. Six variables that contained the most predictive information were selected by discriminant analysis for a group of 6,176 patients who had isolated bypass operations. In descending order of importance they were age, left main coronary artery stenosis greater than or equal to 90%, female sex, left ventricular wall motion score, left ventricular end-diastolic pressure (LVEDP), and râles. Five other groups or subgroups of patients were also analyzed in a similar manner. There is a strong association of OM with advanced age, female sex, and variables associated with left ventricular dysfunction. The risk of OM for an individual patient may be estimated with the use of these clinical and angiographic characteristics.

Adult↗
PubMed1979

Exercise stress testing. Correlations among history of angina, ST-segment response and prevalence of coronary-artery disease in the Coronary Artery Surgery Study (CASS).

To determine to what extent the diagnostic accuracy of stress testing is influenced by the prevalence of coronary-artery disease, we correlated the description of chest pain, the result of stress testing and the results of coronary arteriography in 1465 men and 580 women from a multicentered clinical trial. The pre-test risk (prevalence of coronary-artery disease) varied from 7 to 87 per cent, depending on sex and classification of chest pain. A positive stress test increased the pre-test risk by only 6 to 20 per cent, whereas a negative test decreased the risk by only 2 to 28 per cent. Aothough the percentage of false-positive results differed between men and women (12 +/- 1 per cent versus 53 +/- 3 per cent P less than 0.001), this difference was not seen in a subgroup matched for prevalence of coronary-artery disease. We conclude that the ability of stress testing to predict coronary-artery disease is limited in a heterogeneous population in which the prevalence of disease can be estimated through classification of chest pain and the sex of the patient.

Angina Pectoris↗
PubMed1979

Predictive value of electrocardiographic patterns in localizing left ventricular asynergy in coronary artery disease.

Transmural myocardial infarction by ECG (ECG-MI) was correlated with left ventricular asynergy by biplane left cineventriculography in 200 patients with coronary artery disease. The ability of individual ECG-MI patterns to predict and correctly localize asynergy was: anterior--98 per cent (43 of 44), inferior--82 per cent (36 of 44), true posterior--73 per cent (11 of 15). Of various combinations of criteria for true posterior ECG-MI, the pattern of an R wave and upright T wave in Lead V1 was most predictive of posterior asynergy--80 per cent (8 of 10). The LAO projection demonstrated a wall motion abnormality not appreciated in the RAO in 8 per cent (10 of 122) of cases of inferoposterior asynergy and enhanced assessment of asynergy in 30 per cent (36 of 122) of cases. It is concluded that: (1) ECG-MI has a high predictive accuracy for left ventricular asynergy, (2) an R-wave and upright T wave in Lead V1 is the best ECG predictor of posterior asynergy, and (3) the LAO projection makes an important contribution to the assessment of regional asynergy in coronary artery dieseas.

Electrocardiography↗
PubMed1979

Left ventricular false aneurysm after coronary bypass surgery: radionuclide diagnosis and surgical resection.

A patient with left ventricular pseudoaneurysm formation resulting from myocardial infarction 4 years after coronary bypass surgery is described. The pseudoaneurysm was diagnosed with gated cardiac blood pool imaging and was subsequently successfully surgically repaired. Postoperative pericardial abnormalities predisposing to the possible development of a false aneurysm are discussed. Also, clinical situations in which pseudoaneurysm should be suspected are described, and appropriate diagnostic approaches are outlined.

Coronary Artery Bypass↗
PubMed1979

The effects of gravity on delayed and transplanted delayed tubed flaps.

Altering the position (elevated or dependent) had no immediate effect on the blood supply of delayed or transplanted delayed tubed flaps. However, after 72 hours the mean survival length in the dependent tubes was less than that in the elevated tubes. (This difference was only significant in the delayed untransplanted flaps, and not so in the delayed transplanted flaps). All of the dependent tubes had a significant increase in water content (compared to the elevated tubes). This increase was greater in the transplanted delayed tubed flaps. The tissue pCO2 levels were significantly increased after 24 hours in the dependent transplanted tubes, reflecting poor circulation and ischemia in them. The rate of clearance of subcutaneously injected technetium-99m was significantly increased in the dependent transplanted tubes after 72 hours, while in the elevated tubes the clearance rate was similar to that in normal skin. The morphological appearance of the vessels in these flaps complemented the results of the functional study.

Animals↗
PubMed1979

The blood vessels of psoriasis.

The true microcirculation is the flow of fluid and its contents through the tissues. This is controlled by blood vessels and lymphatics. Both are abnormal in psoriasis and may significantly contribute to its pathogenesis. The type of vasculature characteristic of psoriasis is common to many pathological states and probably influences the metabolism of the tissues in such a way as to maintain the pathology in status quo. It imparts to the tissue a special vulnerability but also encourages repair.

Humans↗
PubMed1978

The predictive value of anginal chest pain as an indicator of coronary disease during exercise testing.

To determine the significance of anginal chest pain during exercise testing, a series of 302 patients undergoing coronary arteriography with exercise testing was reviewed. Of the 302 patients, 85 had ischemic ECG changes and chest pain (Group I); 87 patients had ischemic ECG changes but no chest pain (Group II); 25 patients had chest pain but no ischemic ECG changes (Group III); 105 patients had neither chest pain nor ischemic ECG changes (Group IV). Coronary artery disease was present in 95% of Group I, 75% of Group II, 72% of Group III, and 28% of Group IV. Of those patients with coronary disease, multiple vessels were involved in 94% of Group I, 51% of Group II, 67% of Group III, and 21% of Group IV. The predictive value for presence and extent of coronary disease showed Group I greater than Groups II and III greater than Group IV (p less than 0.025). We conclude that (1) anginal chest pain during exercise testing predicts the presence and extent of coronary disease more accurately than its absence; (2) the presence of chest pain even without an ischemic ECG response during exercise testing appears to be as predictive of coronary disease as an ischemic ECG response alone; and (3) the combination of anginal chest pain during exercise testing and an ischemic ECG response is highly predictive of multivessel coronary artery disease.

Angina Pectoris↗