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Biomedical subjects

T Ryan

Publications and source records attributed to T Ryan.

At least 127 records · Page 7Linked to original sources
PubMed1990

Percutaneous treatments for biliary diseases.

Percutaneous treatment of biliary disease was administered in 173 cases, mainly among high-risk or elderly patients. Diagnosis was acute cholecystitis in 32 cases, acute cholangitis in 16, hepatic abscess in five, gallbladder stones in 28, common bile duct stones in 11, intrahepatic stones in five, malignant obstructive jaundice in 61, and benign biliary stenosis in 15. The treatment was successful in 158 of 173 cases (91.3%). Complications were encountered in 17 (9.8%). Most of these occurred during the initial period and were mild and controllable with conservative treatments. There were two deaths (1.2% of patients); one was not related to the procedure. These data suggest that percutaneous treatments are safe and effective even among elderly or high-risk patients with biliary diseases.

Adult↗
PubMed1989

Upright bicycle exercise echocardiography after coronary artery bypass grafting.

Upright bicycle exercise echocardiography and coronary angiography were performed in 42 patients from 1 month to 15 years (mean 6.3 years) after coronary artery bypass grafting (CABG) to determine if exercise-induced wall motion abnormalities could be correlated with the presence and location of nonrevascularized vessels. Nonrevascularized vessels were defined as obstructed vessels without grafts, obstructed grafts or native vessels obstructed distal to bypass graft insertion. Adequate quality echocardiograms were recorded at rest, peak exercise and after exercise in 38 patients (90%). Rest and postexercise echocardiograms were adequate in 3 others. Only 1 patient was excluded from analysis for inadequate peak and postexercise echocardiograms. Exercise-induced wall motion abnormalities were present in 33 of 35 patients (94%) who had 1 or more nonrevascularized vessels and these abnormalities were absent in 5 of 6 (83%) who had all vessels revascularized. Wall motion abnormalities were localized to the territory of the left anterior descending (LAD) artery or to a combined right (R) coronary-left circumflex (LC) region of circulation. Exercise-induced wall motion abnormalities were present in 24 of 27 LAD artery regions (89%) and 23 of 26 R-LC regions (88%) that had nonrevascularized vessels. These abnormalities were absent in 13 of 14 LAD regions (93%) and in 12 of 15 R-LC regions (80%) that had only revascularized vessels. Upright bicycle exercise echocardiography was successfully performed after CABG. The technique detected and accurately localized nonrevascularized and revascularized vessels.

Adult↗
PubMed1989

Exercise echocardiographic detection of coronary artery disease in women.

The utility of exercise echocardiography for the diagnosis of coronary artery disease has been demonstrated in populations consisting largely of men with a high prevalence of disease. To determine the diagnostic value of exercise echocardiography in women, 57 women who presented with chest pain were studied with coronary cineangiography and echocardiography combined with either treadmill (n = 38) or bicycle exercise (n = 19). Significant coronary artery disease (greater than or equal to 50% reduction in luminal diameter) was present in 28 (49%) of 57 patients, including 16 (84%) of 19 who had typical angina, and 12 (32%) of 38 who had atypical chest pain. The overall sensitivity and specificity of echocardiography were both 86%. Exercise echocardiography correctly determined the presence or absence of coronary artery disease in 32 (84%) of 38 patients who had atypical chest pain and in 17 (89%) of 19 who had typical angina (p = NS). The exercise electrocardiogram (ECG) was nondiagnostic in 17 patients (30%) who had rest ST segment depression or ST depression with exercise that could also be induced by hyperventilation or changes in position. The correct diagnosis was made by echocardiography in 14 (82%) of 17 patients with a nondiagnostic exercise ECG. In conclusion, exercise echocardiography has a clinically useful level of sensitivity and specificity for the detection of coronary artery disease in women. The technique provides diagnostic information in women presenting with atypical chest pain and in those who have a nondiagnostic exercise ECG.

Adult↗
PubMed1989

Early recovery of regional left ventricular function after reperfusion in acute myocardial infarction assessed by serial two-dimensional echocardiography.

Although global and regional left ventricular (LV) function has been demonstrated to improve after reperfusion in acute myocardial infarction (AMI), the timing of these changes has not been well established. In this study, serial 2-dimensional echocardiography was used to assess regional LV function in 23 patients with AMI in whom reperfusion was accomplished by thrombolysis alone, by coronary angioplasty alone or by both interventions within 6 hours after onset of chest pain. Echocardiograms were performed before or within 6 hours after reperfusion (n = 23) and at 1 (n = 19), 3 (n = 21) and 7 (n = 20) days after reperfusion. Wall motion index and percentage of normally functioning muscle were calculated using a 16-segment scoring system analyzed in blinded fashion without knowledge of patient identity, therapy or time of study. The mean wall motion index improved from 1.78 +/- 0.48 to 1.56 +/- 0.38 at 1 day (n = 19, p less than 0.01), and to 1.48 +/- 0.37 at 3-7 days (p less than 0.01), with no significant difference between 3 days (1.49 +/- 0.39) and 7 days (1.42 +/- 0.30). There was a corresponding improvement in the percentage of normally functioning muscle, from 53 +/- 24% at 6 hours to 62 +/- 20% at 1 day (p less than 0.05) and to 67 +/- 18% at 3-7 days (p less than 0.01), again with no significant difference between 3 days (67 +/- 21) and 7 days (70 +/- 20).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Ketosis, a complication of theophylline toxicity.

A case of prolonged theophylline toxicity in a young non-diabetic female is reported. Blood gas analysis revealed a mixed respiratory alkalosis and metabolic acidosis. The metabolic acidosis was due to ketoacids, which were detected in the patient's breath and urine. The ketones cleared rapidly when theophylline elimination was increased with activated charcoal, i.v. metoprolol reduced excessive b-adrenergic stimulation and a 10% dextrose infusion repleted hepatic glycogen. Theophylline is known to increase free fatty acid levels. It is postulated that prolonged fasting led to depletion of hepatic glycogen and that ketones were generated by metabolism of elevated serum fatty acids. In previous reviews of the metabolic abnormalities associated with theophylline toxicity ketosis has not been described.

Acidosis↗
PubMed1989

Non-invasive diagnosis of ischemic heart disease using stress thallium scintigraphy and digital exercise 2-dimensional echocardiography.

The introduction of computer technology has overcome many of the technical difficulties in performing and interpreting echocardiograms obtained from exercising individuals and has made stress echocardiography a potentially practical examination. Additional data, however, are necessary to establish the accuracy of exercise echocardiography. The purpose of this study is to compare exercise echocardiography and planar thallium studies for accuracy in detecting coronary artery disease. The study was performed on 50 patients, 41 of whom underwent coronary angiography. For the remaining 9 patients accuracy was defined as concordance of clinical information, treadmill ECG results, thallium data and the exercise echocardiogram. If there was any discrepancy among these tests, the patient was not included in the analysis. The sensitivity of exercise 2D digital echocardiography was comparable to stress thallium (0.86 vs 0.85) and was better than treadmill test alone (0.66). There were no false positive tests with echocardiographic study, while 1 false positive thallium examination was detected. The diagnostic accuracy of stress echocardiography was 0.90, stress thallium 0.85 and treadmill test only 0.75. In conclusion, exercise echocardiography appears to give results comparable to stress planar thallium studies. In addition, the ultrasonic procedure has several advantages: it is totally non-invasive, does not require a reperfusion study 4 hours later, avoids radiation and is less expensive.

Adult↗
PubMed1989

Oxygen consumption during sleep: influence of sleep stage and time of night.

We measured oxygen consumption (VO2) in eight normal male volunteers during sleep, using the ventilated-hood method. Data were collected over 28 subject-nights. There was an overnight trend of gradually decreasing VO2 in the first 4 h, followed by a rise toward the morning. The minimum VO2 was 7.9% lower than that in the first hour. To examine the influence of sleep stages on the VO2, we compared the VO2 of a sleep stage (an overnight average of all epochs in that stage) with that of other stages. The results show that VO2 values in stages awake and 1 are significantly higher than all other stages. Stage rapid eye movement (REM) is significantly lower than stage 2, but stages 3 and 4 are not different from each other or from stages REM and 2. We also compared VO2 of sleep stages that occurred close to each other (within the same hour). VO2 in awake stage is again significantly higher than in all other stages, and stage 2 is higher than stages 3 and 4. However, no difference is found between stage 1 and stages 2, 3 and REM, nor is there any difference between REM and stages 2 and 3. The discrepancy between close-stage comparison and overnight-average comparison can be accounted for by the variation in VO2 of an individual stage with the time of night. Although there is a variation in time distribution of the stages overnight, this factor influences the overnight trend of VO2 in a minor fashion only.

Adult↗
PubMed1988

Developmentally regulated telomere addition in Tetrahymena thermophila.

To investigate the developmentally programmed telomere addition that accompanies chromosome fragmentation during macronuclear differentiation in Tetrahymena thermophila, five representative telomeric regions from the macronucleus were cloned and characterized in detail. The sequences adjacent to the telomeric (C4A2:T2G4) repeats on these five macronuclear ends had no significant sequence homology or shared secondary structure. Two developmentally independent examples of one macronuclear telomere had a 5 base pair difference in the position of the junction between the telomeric repeats and the adjacent sequences. A telomere-adjacent sequence, in the form of a synthetic oligonucleotide, was unable to prime the addition of telomeric repeats in vitro. The implications of these results for the mechanisms underlying developmentally programmed chromosome fragmentation and telomere addition in Tetrahymena are discussed.

Animals↗
PubMed1988

Improvement in regional wall motion after percutaneous transluminal coronary angioplasty during acute myocardial infarction: utility of two-dimensional echocardiography.

In the setting of acute myocardial infarction, 16 patients undergoing successful coronary angioplasty (PTCA) within 6 hours of presentation (group I) and eight patients receiving conventional medical therapy (group II) were studied by serial two-dimensional (2D) echocardiography to assess the functional recovery of myocardium. All patients underwent 2D echocardiograms within 24 hours of presentation and at a minimum of 6 days after admission. Wall motion analysis was quantified with a wall motion score index based on 16 left ventricular wall segments. Wall motion score index improved significantly from early to late echocardiographic study in the patients undergoing PTCA (1.65 +/- 0.29 to 1.40 +/- 0.30; p less than 0.001), whereas the index did not improve in the conventionally treated group (1.54 +/- 0.26 to 1.58 +/- 0.25; p = NS). One patient in group II had a greater than or equal to 10% improvement in wall motion score index compared to 11 of 16 in group I (p less than 0.01). In all cases improvement in wall motion score index was due to improvement in regional wall motion in the area of infarction. In group I, 40 of 77 (52%) infarct zone segments showed improvement of at least one grade, versus 4 of 28 (14%) segments in group II (p less than 0.001). These data indicate that regional myocardial function improves in the majority of patients undergoing successful PTCA as emergency therapy for acute myocardial infarction and that serial 2D echocardiography is an excellent means to quantify this improvement.

Adult↗
PubMed1988

Exercise echocardiography: detection of coronary artery disease in patients with normal left ventricular wall motion at rest.

Most studies investigating the ability of exercise two-dimensional echocardiography to identify patients with coronary artery disease have included patients with left ventricular wall motion abnormalities at rest. This has the effect of increasing sensitivity because patients with only abnormalities at rest are detected. To determine the diagnostic utility of exercise echocardiography in patients with normal wall motion at rest, 64 patients were studied with exercise echocardiography in conjunction with routine treadmill exercise testing before coronary cineangiography. All 24 patients who had no angiographic evidence of coronary artery disease had a negative exercise echocardiogram (100% specificity). Nine of 40 patients with coronary artery disease (defined as greater than or equal to 50% narrowing of at least one major vessel) also had a negative exercise echocardiogram (78% sensitivity). Of the nine patients with a false negative exercise echocardiographic study, six had single vessel disease. Among 25 patients with single vessel disease, exercise echocardiography was significantly more sensitive (p = 0.01) than treadmill exercise testing alone (76 versus 36%, respectively). Among 15 patients with multivessel disease, the two tests demonstrated similar sensitivity (80%). In conclusion, exercise echocardiography is highly specific and moderately sensitive for the detection of coronary artery disease in patients with normal wall motion at rest. Although exercise echocardiography is significantly more sensitive than treadmill exercise electrocardiographic testing alone in patients with single vessel disease, the two tests are similar in their ability to detect coronary artery disease in patients with multivessel disease and normal wall motion at rest.

Adult↗
PubMed1987

Digital two-dimensional echocardiographic imaging of the proximal left anterior descending coronary artery.

The use of 2-dimensional echocardiography to evaluate coronary artery anatomy noninvasively and directly has been primarily limited to the evaluation of the left main coronary artery. To determine the feasibility of visualization of the proximal left anterior descending coronary artery (LAD) and assessment for atherosclerotic disease in this location, 128 consecutive patients undergoing coronary arteriography were evaluated with digital 2-dimensional echocardiography. Visualization of the proximal LAD was possible in 90 (70%) of the 128 patients. Of 45 patients with proximal LAD narrowing by angiography, digital echocardiography correctly identified 44 (98% sensitivity). In 27 patients with angiographically normal coronary arteries, digital echocardiography was normal in 18 (67% specificity). In the 18 patients with an angiographically normal proximal LAD but narrowing elsewhere in the coronary system, digital echocardiographic evaluation of the proximal LAD was abnormal in 15. This initial study suggests that 2-dimensional echocardiography is a feasible technique to image the proximal LAD noninvasively in patients undergoing coronary arteriography.

Adult↗