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J L Ritchie

Publications and source records attributed to J L Ritchie.

142 records · Page 8Linked to original sources
PubMed1977

Myocardial imaging with intravenously injected thallium-201 in patients with suspected coronary artery disease: analysis of technique and correlation with electrocardiographic, coronary anatomic and ventriculographic findings.

Myocardial imaging was performed after intravenous injection of thallium-201 at rest in 50 patients with suspected coronary artery disease and the results were compared with electrocardiographic, ventriculographic and coronary arteriographic findings. The thallium-201 myocardial images were of good quality and compared favorably with images previously obtained with intracoronary particle injection. Myocardial to background ratios averaged 2:1, a considerable improvement over ratios reported with potassium-43. There was complete intra- and interobserver agreement in the interpretation of images in 90 and 82 percent of cases, respectively. Major disagreement occurred in less than 5 percent of cases. Overall, 15 (30 percent) had an abnormal, 10 patients (20 percent) a borderline abnormal and 25 patients (50 percent) a normal myocardial image. Of patients with electrocardiographic Q waves, 91 percent had an image defect. Of 39 patients without Q waves, 13 percent had an image defect. All 30 patients with a normal or borderline abnormal thallium-201 image had a normal ventricular contraction pattern. All patients with a segmental ventriculographic abnormality had an image defect. In all cases, the area of electrocardiographic or ventriculographic abnormality corresponded to the area of the thallium-201 image defect. The systolic ejection fraction was depressed (0.49 +/- 0.18 [mean +/- standard deviation]) in patients with an image defect compared with that in patients with a normal image (0.64 +/- 0.06, P less than 0.005). Coronary arterial lesions were present and usually of high grade in all patients with an abnormal image; however, the presence of high grade coronary stenosis or occlusion as such correlated with image defects only to the extent that prior myocardial infraction was associated. Thus, satisfactory myocardial images at rest appear to be obtained with intravenously administered thallium-201 and electrocardiographic, ventriculographic and coronary arteriographic data suggest that image defects denote regions of prior myocardial infarction.

Coronary Angiography↗
PubMed1977

Platelet and fibrinogen survival in coronary atherosclerosis. Response to medical and surgical therapy.

Survival times of chromium-51 platelets and iodine-125 fibrinogen were determined in 58 men with documented coronary atherosclerosis. Compared with findings in a control group of 28 men of similar age, mean platelet survival time was selectively shortened (6.8 +/- 1.8 [standard deviation] days versus 9.0 +/- 1.0 days; P less than 0.0001) without a decrease in fibrinogen survival time. More than half of the patients (31 of 58) had a platelet survival time of less than 7.0 days (2 standard deviations from the mean survival time in control subjects). Mean platelet survival time improved toward normal in nine patients after coronary revascularization (preoperative 5.1 +/- 0.9 days, postoperative 7.1 +/- 1.5 days; P less 0.001) and in 13 patients after administration of dipyridamole and acetylsalicylate (4.8 +/- 0.5 days versus 7.0 +/- 0.8 days; P less than 0.001). We conclude that selective platelet consumption occurs in atherosclerotic coronary vessels of some patients and that medical or surgical intervention may inhibit this process.

Adult↗
PubMed1977

Myocardial imaging with thallium-201 at rest and during exercise. Comparison with coronary arteriography and resting and stress electrocardiography.

Myocardial imaging with intravenous thallium-201 (201Tl) was performed at rest and following maximal treadmill exercise in 101 patients with suspected coronary artery disease. Results were interpreted from Polaroid scintiphotos by three independent observers with complete interobserver agreement in 79%. Of 25 patients with no or insignificant coronary artery disease (less than 50% diameter stenosis), one (4%) had a resting 201Tl image defect, one (4%) had an exercise 201Tl defect, none had an ECG Q wave, and four (16%) had exercise ST-segment depression. Among 76 patients with coronary artery disease (greater than or equal to 50% diameter stenosis), 58 (76%) had a defect on either the rest or exercise 201Tl image. The proportion of patients with an exercise image defect (50/76, 66%) was greater than the proportion with exercise ST depression alone (34/76, 45%; P less than 0.02). Overall, 69 of the 76 (91%) patients with coronary artery disease had either a positive rest or exercise myocardial image and/or a positive rest (ECG Q waves) or exercise (ST depression) electrocardiogram. This exceeded the proportion with only rest or exercise electrocardiographic abnormalities (50/76, 65%; P less than 0.001). We conclude that rest and exercise myocardial imaging with 201Tl is easily accomplished with readily available imaging equipment. The image data enhanced the diagnostic sensitivity of stress electrocardiography, and provided spatial identification of the abnormal segment(s) of myocardium.

Adult↗
PubMed1977

Thallium-201 myocardial imaging before and after coronary revascularization: assessment of regional myocardial blood flow and graft patency.

Twenty patients underwent myocardial imaging with Thallium-201 (201Tl) before and subsequent to coronary artery bypass grafting. All patients had rest and maximal treadmill exercise imaging postoperatively. Eleven of the 20 patients had rest and exercise 201Tl images preoperatively; 9/20 only had rest imaging preoperatively. Postoperative regional exercise perfusion was improved in seven of the 11 patients who had preoperative exercise images, and was associated with regional graft patency in each case. Thirteen of 20 patients showed no new defect with postoperative exercise imaging. The remaining seven patients developed or had an increased defect with exercise. The patients with no new perfusion defects during postoperative study has 26/30 grafts patent (87%). Patients developing a new perfusion defect with exercise had fewer grafts patent (7 of 13 [54%]; P less than 0.03). In these seven cases, a new exercise-induced defect was associated with regional graft closure or residual nonoperated disease. Knowledge of the preoperative coronary anatomy allowed the distinction between ungrafted areas and regional graft dysfunction. We conclude that preoperative and postoperative 201Tl imaging may noninvasively predict graft closure and/or improved regional perfusion with patent grafts.

Angina Pectoris↗
PubMed1977

The radionuclide ejection fraction: a comparison of three radionuclide techniques with contrast angiography.

Left-ventricular ejection fraction (EF) can be measured by several radionuclide methods. The EFs determined by three such methods (first-transit time-activity, equilibrium blood-pool time-activity, and equilibrium blood-pool area-length) were compared in 30 patients with EFs measured by area-length analysis of x-ray contrast angiograms. Both time-activity methods (first-transit and blood-pool) yielded EFs that correlated well with x-ray contrast EFs (r=0.86 and 0.84, respectively). Area-length analysis of blood-pool images yielded EFs that agreed less well with x-ray contrast EFs (r=0.73 in the RAO view, 0.70 in the LAO view). We conclude that first-transit and blood-pool techniques are equally accurate methods for determining EF when the time-activity method of analysis is employed.

Adult↗
PubMed1976

Refractory ventricular tachycardia and fibrillation in a patient with the prolapsing mitral leaflet syndrome: successful control with overdrive pacing.

A 56 year old man with the prolapsing mitral leaflet syndrome presented with syncope and recurrent ventricular tachycardia and fibrillation. Treatment with antiarrhythmic agents (lidocaine, procainamide and propranolol) was unsuccessful. Overdrive pacing, in combination with propranolol, successfully suppressed the arrhythmias, and the patient remains well after 15 months of follow-up.

Death, Sudden↗
PubMed1976

Myocardial imaging with radionuclide-labeled particles. Analysis of the normal image, abnormal image, and technical consideration.

Myocardial imaging following the direct injection of labeled particles is an effective and safe method of studying regional perfusion. Perfusion defects can conveniently be classified as apical, anterior, inferior, or posterior and related to the distribution of specific coronary arteries. The hemodynamic effects of contrast material, inadequate mixing of particles, coronary anatomy, and associated cardiac pathology are important technical considerations affecting the performance and interpretation of studies using this technique.

Albumins↗
PubMed1975

Myocardial perfusion imaging with 99m-Tc or 113m-In macroaggregated albumin: correlation of the perfusion image with clinical, angiographic, surgical, and histologic findings.

Scintillation camera myocardial perfusion images were performed in 77 patients with proved or suspected ischemic heart disease following the intracoronary injection of 1.5 mCi 99m-Tc or 113m-In macroaggregated albumin. Perfusion images were classified as normal (36) or abnormal (41), and the location of abnormality was noted. Thirty-seven out of 41 patients with abnormal images had prior myocardial infarction based on history (30), ECG Q-waves (27), local contraction pattern abnormality (23), or direct surgical (9) or histologic (4) inspection, either singly or in combination. Three out of five patients with pre-infarction angina had image defects-none had evidence of infarction by ECG, ventriculogram, or surgical inspection. Coronary artery stenosis correlated with image defects to the extent that myocardial infarction was associated; 28 out of 29 patients with total occlusions and other evidence of infarction had image defects, four patients with complete occlusions but without other evidence of infarction had normal images. We conclude that, excepting patients with pre-infarction angina, this technique is more sensitive and direct in the identification of myocardial scar than standard ECG, clinical evaluation, or biplane left ventriculography.

Autopsy↗
PubMed1975

Myocardial imaging with indium- 113m- and technetium-99m-macroaggregated albumin. New procedure for identification of stress-induced regional ischemia.

Regional coronary blood flow distribution was studied by myocardial imaging after intracoronary injection of technetium-99m- and indium-113m-macroaggregated albumin at rest and during coronary hyperemia induced by intracoronary injection of Hypaque-M, 75 percent. The four- to five-fold increase in coronary flow after injection of radiographic contrast material was similar in magnitude to that occurring with maximal exercise stress. Experimentally, resting coronary blood flow and regional distribution of radioactive particles remains normal in spite of coronary stenosis of up to 85 percent. Less severe stenosis causes flow and distribution abnormalities only during periods of increased flow, and the degree of maldistribution is directly related to the physiologic severity of the stenosis. Of 49 patients with suspected coronary artery disease, 10 had no significant lesions by coronary arteriography and all had normal images at rest and during coronary hyperemia. Thirty-seven of 39 patients with significant obstructive coronary artery disease had abnormal images at rest or during contrast agent-induced hyperemia, or both. Patients with significant coronary artery disease without previous infarction usually demonstrated abnormalities in flow distribution only during coronary hyperemia. Patients with previous infarction demonstrated resting perfusion abnormalities that often became more abnormal during hyperemia. This technique provides a new method for assessing the physiologic effects of coronary stenosis in conjuntion with coronary arteriography.

Albumins↗
PubMedDate not supplied

Time- and dose-dependent changes in ejection fraction after anthracycline therapy.

Cardiac toxicity due to anthracycline therapy is dose related, and congestive failure is a major limiting factor to therapy. Radionuclide cardiac evaluation provides a sensitive noninvasive method for detecting changes in cardiac function. Fifteen patients receiving either doxorubicin or daunomycin were evaluated with radionuclide ejection fractions (EFrn). The data indicate that the EFrn can detect an acute depressant cardiac action of these drugs as early as 24 hr after drug administration. In addition, a cumulative or chronic cardiac depression was noted; cumulative dosage of doxorubicin or daunomycin correlated with a reduced EFrn (p less than 0.001). We conclude that (1) the EFrn can noninvasively detect significant changes in cardiac function at low cumulative doses of doxorubicin or daunomycin and (2) the EFrn may be useful in evaluating cardiac function in patients during doxorubicin or daunomycin therapy.

Adult↗
PubMedDate not supplied

Age-related alterations in basal expression and in vitro, tumour necrosis factor alpha mediated, upregulation of CD11b.

BACKGROUND: The beta(2-)integrin CD11b (Mac-1) plays a crucial role in the firm attachment of leucocytes to the endothelium during the inflammatory response. OBJECTIVE: This study aimed to determine whether the increased incidence of infections witnessed in elderly individuals compared to their younger counterparts was associated with deficiencies in basal expression and/or upregulation of CD11b. METHODS: Flow cytometry was used to measure CD11b expression, before and after in vitro tumour necrosis factor alpha (TNF-alpha) stimulation, on neutrophils, monocytes and lymphocytes from healthy volunteers aged less than 36 years and Senieur-approximated 70-85 and over 85 year olds. The TNF-alpha levels in serum were measured using a commercially available enzyme-linked immunoassay technique. RESULTS: The basal expression of CD11b on monocytes and lymphocytes was highest in the 70-85-year-olds and lowest in the > 85-year-olds. Following in vitro stimulation using low (10 IU) and high (100 IU) TNF-alpha concentrations, subjects > 85 years consistently showed significantly lower increases in CD11b expression on each of the three cell types. The maximal increase in CD11b expression was in the 70-85-year age group for neutrophils and monocytes and in < 36-year-olds for lymphocytes. Serum TNF-alpha was significantly higher in the elderly groups. Regression analysis showed a significant association between TNF-alpha and expression of CD11b on lymphocytes before and after TNF-alpha stimulation and for neutrophils before stimulation. CONCLUSIONS: The results of this study suggest that CD11b expression on leucocytes may not be consistent throughout life. Such age-related changes could compromise the inflammatory response, rendering individuals > 85 years old more susceptible to infections. Alternatively, the lower levels of CD11b expression in this group may represent downregulation and protection against excess leucocyte activation within the vascular system and may, therefore, provide a mechanism for successful ageing.

Adult↗
PubMedDate not supplied

Institutional volumes and coronary angioplasty outcomes before and after the introduction of stenting.

CONTEXT: An increasing number of patients undergoing percutaneous transluminal coronary angioplasty (PTCA) are receiving coronary stents. OBJECTIVES: To assess whether the introduction of coronary stenting has changed hospital mortality or same-admission coronary artery bypass grafting (CABG) and whether the hospital's procedure volume affects these outcomes. DESIGN: Observational study using hospital claims. SETTING: Nonfederal hospitals that performed PTCA in California in 1993 and 1996. PATIENTS: 35,350 patients who underwent PTCA in 1993 (before the introduction of stenting) and 43,040 patients who had PTCA in 1996 (43% of whom received stents). MEASUREMENTS: Hospital stenting volumes for 1996 were divided into terciles; total PTCA procedures per year were categorized as low (< or = 200), medium (201 to 400), or high (> 400). Outcome variables included hospital death and coronary artery bypass grafting (CABG) performed during the same admission. Patients with a principal diagnosis of acute myocardial infarction (AMI) were analyzed separately from those without such a diagnosis. RESULTS: From 1993 to 1996, the characteristics of patients undergoing PTCA did not change substantially. The use of same-admission CABG decreased by 13% (from 6.0% to 5.2%; P = 0.008) in the AMI group and by 30% (from 3.7% to 2.6%; P < 0.001) in the no-AMI group. Hospital mortality did not change significantly in either group. Procedure volume was not related to hospital mortality. However, rates of same-admission CABG were significantly lower at hospitals with high annual stenting volumes than at low-volume centers (1.3% vs. 2.3% among patients in the no-AMI group; P < 0.001). CONCLUSIONS: Hospital mortality rates after PTCA have not changed considerably since the introduction and diffusion of coronary stenting. However, rates of same-admission CABG have decreased in recent years and are lowest at hospitals with high procedure volumes.

Aged↗