Use of flecainide acetate in the treatment of supraventricular tachyarrhythmias.
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Arrhythmias, Cardiac↗
Biomedical subjects
T H Marwick
Publications and source records attributed to T H Marwick.
Severe hypophosphataemia induced by glucose-insulin-potassium therapy. A case report and proposal for altered protocol.
A case is described where severe hypophosphataemia was induced by a widely used protocol for glucose-insulin-potassium (GIK) infusion. Hypophosphataemia was found to be a universal sequel to the use of this infusion. A new regimen for administering this agent was designed, and shown to lack the potentially serious side effect of phosphate depletion.
Aged↗
Management of familial aortic dissection.
Aortic dissection uncommonly occurs in multiple family members, and this association is most commonly seen in kindreds with Marfan's syndrome. There is increasing evidence that such connective tissue disturbances may not always appear in their complete phenotypic pattern. This report describes two siblings with aortic dissection. It is proposed that this suggests underlying connective tissue disease and warrants investigation of close relatives.
Adult↗
Abdominal wall haematoma related to prophylactic heparin therapy.
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Abdominal Muscles↗
Cirrhosis and hepatocellular carcinoma in a patient with heterozygous (MZ) alpha-1-antitrypsin deficiency.
A patient is described with micronodular cirrhosis, partial (heterozygous, MZ) deficiency of alpha-1-antitrypsin (AAT) and hepatocellular carcinoma. The patient did not drink alcohol and all serological markers of infection with hepatitis B virus were absent. Death was due to intra-peritoneal bleeding from a multifocal liver tumour. Histology revealed multiple intracytoplasmic AAT globules in hepatocytes at the periphery of the cirrhotic nodules. Copper granules, present in the same non-neoplastic liver cells may have resulted from minor cholestasis. Within the neoplastic hepatocytes AAT globules were sparse and copper deposits co-existed with the globular variant of Mallory bodies. The case is presented in support of the postulated association of partial deficiency of AAT, chronic liver disease and hepatic neoplasia.
Aged↗
Post-prandial glucose and insulin responses to different types of spaghetti and bread.
The glycemic response following ingestion of carbohydrate in various forms is different. The factors involved are not fully elucidated. In this study the glycemic and insulin responses to 50 g of carbohydrate in the form of white bread (WB), semolina bread (SB), white spaghetti (WS) and wholemeal spaghetti (BS) were compared in ten noninsulin-dependent diabetics. The responses were assessed by calculating the area under the curve. WB and SB had significantly higher glycemic responses compared with WS and BS (P less than 0.01). There was no difference in glycemic response between either form of bread, or either type of spaghetti. Similarly WB and SB had greater insulin responses than WS and BS (P less than 0.05). There was no difference in insulin response between WB and SB but BS had a greater response than WS (P less than 0.01) attributed to the higher protein content of BS. Thus, in this study the physical form of the food was a major factor influencing the glycemic response, and other factors such as particle size and fibre content had negligible effects.
Adult↗
Evaluation of the extent and timing of the coronary hyperemic response to dipyridamole: a study with transesophageal echocardiography and positron emission tomography with oxygen 15 water.
Coronary flow reserve may be measured with Doppler-derived coronary blood-flow velocity or scintigraphic assessment of myocardial perfusion. The purpose of this study was to compare coronary flow velocity and perfusion measures of flow reserve with respect to their extent and time course. Coronary flow velocity reserve in the proximal left anterior descending coronary artery measured by pulsed-wave Doppler at transesophageal echocardiography, with measures of perfusion reserve obtained in the corresponding territory, were measured by a standard O15 water technique at positron emission tomography. Eighteen male volunteers underwent both tests on different days in random order, with dipyridamole stress (0.56 mg/kg). After correction of resting flow and perfusion measurements to a standard cardiac workload (to compensate for heterogeneity in hemodynamics between the two studies), coronary flow reserve was calculated as the ratio between dipyridamoleand corrected resting flow. The uncorrected perfusion reserve measured by positron emission tomography was 3.7 +/- 1.2, compared with a corrected perfusion reserve of 2.3 +/- 0.7. This correlated with a corrected flow velocity reserve of 2.9 +/- 1.0 at transesophageal echocardiography (R = 0.92; p < 0.001). The mean difference between these results was 0.58 +/- 0.41; discrepant results occurred at higher flows, in the presence of discordant blood pressure responses to stress, and because of intersubject variations in the timing of the peak coronary flow response, which were detected by continuous monitoring at transesophageal echocardiography. Measurement of coronary flow reserve at transesophageal echocardiography correlates well with measurements at positron emission tomography, and discrepancies are minimized if measurements are taken at the same time after dipyridamole.
Adult↗
Detection and evaluation of intrapulmonary vascular shunt with "contrast Doppler" transesophageal echocardiography.
Contrast echocardiography is useful for detecting intrapulmonary right-to-left shunt lesions. In a patient with suspected pulmonary arteriovenous fistula, contrast transesophageal echocardiography was used to demonstrate the presence of a right-to-left shunt. By use of a combination of two-dimensional echocardiography, contrast injection, and pulsed Doppler echocardiography, each pulmonary vein was successfully interrogated for evidence of contrast shunting. This case demonstrates that contrast transesophageal echocardiography is useful for the detection of intrapulmonary fistulas and that it has the potential for localization of the shunt lesion.
Arteriovenous Malformations↗
Diagnosis of coronary artery disease using exercise echocardiography and positron emission tomography: comparison and analysis of discrepant results.
Both exercise echocardiography and rubidium-82 positron emission tomography are used in the detection and characterization of coronary artery disease. This study compared results of both in 74 patients with known coronary anatomy, by use of exercise echocardiography before and after treadmill exercise and positron emission tomography with intravenous dipyridamole-handgrip stress. Significant (greater than 50%) coronary stenoses were present in 70 patients; exercise echocardiography and positron emission tomography each identified 63 patients (sensitivity 90%). Significant stenoses without previous myocardial infarction were present in 34 patients; 29 (85%) were identified by exercise echocardiography and 28 by positron emission tomography (82%, p = NS). Four patients had no significant coronary disease, and were all identified as normal by both methods. Segments were classified as either normal or showing stress or resting abnormalities, and the diagnoses were compared in the territories of the three major coronary arteries. Results were concordant with respect to the presence or absence of coronary disease in 185 of 222 territories (83%). The remaining 37 regions had abnormalities by exercise echocardiography or positron emission tomography but not both. Stress defects were identified by only one of the tests in 24 areas (in 12 [50%], angiographic findings correlated with positron emission tomography). Resting defects were diagnosed by only one modality in 13 regions (angiographic findings correlated with the results of positron emission tomography in 9 [69%] of these). Both exercise echocardiography and positron emission tomography are sensitive for the identification of coronary artery disease, although on a regional basis, positron emission tomography appears to be more specific for the diagnosis of resting perfusion defects.
Coronary Disease↗
Left atrial tamponade: diagnosis by transesophageal echocardiography.
A 60-year-old white man became hypotensive and dyspneic 3 days after right pneumonectomy for bronchogenic carcinoma. Transthoracic echocardiography was nondiagnostic because of technical difficulty. Transesophageal echocardiography demonstrated a loculated posterior pericardial effusion with isolated diastolic left atrial collapse. The hemodynamic disturbance resolved after drainage of the effusion. Transesophageal echocardiography plays a valuable role in the diagnosis of postoperative cardiac tamponade.
Cardiac Tamponade↗
The incidence of scintigraphically viable and nonviable tissue by rubidium-82 and fluorine-18-fluorodeoxyglucose positron emission tomographic imaging in patients with prior infarction and left ventricular dysfunction.
BACKGROUND: Although reversible perfusion defects, perfusion-metabolism mismatch and match patterns are important for differentiating viable from nonviable myocardium, the frequency of these scintigraphic patterns has not been reported. The study objective was to establish the incidence of these scintigraphic patterns to estimate the clinical need for metabolic positron emission tomography for evaluating tissue viability in patients with prior myocardial infarction (MI). METHODS AND RESULTS: 82Rb perfusion images were interpreted to identify reversible or irreversible defects, followed by determination of their 18F-fluorodeoxyglucose (18F-FDG) uptake pattern. In 155 patients with prior MI, analysis of 613 abnormal segments showed reversible perfusion defects in 13%. The 87% irreversible defects, 18% showed perfusion-metabolism mismatch, whereas 69% showed the match pattern. Reversible perfusion defects and perfusion-metabolism mismatches were noted in 20% (31/155) and 29% (45/155) of patients, respectively, whereas the match pattern was noted in 51% (79/155) of patients. CONCLUSION: Irreversible perfusion defects were common in our patients with prior MI, and distinction between viable and nonviable tissue was not possible by perfusion imaging alone. The identification of hibernating myocardium was possible only with the additional 18F-FDG imaging in about one third of patients. This indicates a significant clinical demand for 18F-FDG imaging that identifies patients who will benefit from revascularization.
Adult↗
Physiologic evaluation of coronary flow: the role of positron emission tomography.
As the complexity, cost, and risks of cardiac interventions direct attention to careful selection of patients, the ability of diagnostic imaging techniques to provide quantitative documentation of the hemodynamic severity of coronary artery disease will assume greater importance. Among the various techniques currently in use, positron emission tomography yields superior spatial resolution and attenuation correction and has high sensitivity and specificity. The correlation of positron emission tomography results with coronary stenosis severity and the possibility of making quantitative flow measurements using oxygen-15 water suggest that cardiac positron emission tomography may be the best noninvasive approach for diagnostic purposes.
Coronary Angiography↗
Coronary artery disease in renal transplant recipients.
BACKGROUND: Coronary artery disease is a major cause of death in transplant recipients. PURPOSE: To review current approaches for the detection, evaluation, and treatment of coronary artery disease in transplant recipients. SUMMARY: Renal transplantation promotes the development of coronary artery disease primarily because immunosuppressant medications accentuate known coronary risk factors such as hypertension, hypercholesterolemia, and hyperglycemia that accelerate the progression of coronary artery disease existing before transplantation. Physicians can monitor a patient's risk status by regular inquiries for symptoms and by simple clinical tools such as the Framingham Study Coronary Heart Disease Risk Prediction Chart in asymptomatic patients. Patients found to be at high risk for coronary artery disease can then undergo dobutamine echocardiography or other noninvasive tests, and patients with positive studies can subsequently undergo angiography. The cost-effectiveness of such an approach is presented. In recent studies at our institution, patients with coronary artery disease had decreased numbers of CD2+ and CD3+ circulating lymphocytes. In addition, in immunosuppressed transplant recipients with coronary artery disease, there was a decrease in CD8+ lymphocytes, whereas in nonimmunosuppressed, nontransplant patients there was a decrease in CD4+ lymphocytes. CONCLUSIONS: A systematic approach to screening patients for coronary artery disease before transplantation can identify those at highest risk and potentially save money and lives. Possible new avenues of research may focus on the role of the lymphocytes in coronary atherosclerosis.
Coronary Disease↗
Assessing myocardial ischemia, hibernation, and viability: stress echocardiography and nuclear imaging.
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Aged↗
Evaluating cardiac risk in noncardiac surgery patients.
The cornerstones of the evaluation of cardiac risk in patients undergoing noncardiac surgery remain a thorough history and physical examination, and a resting electrocardiogram. However, new techniques to assess cardiac function allow more complete evaluation of high-risk patients.
Algorithms↗
Use of exercise electrocardiography, technetium-99m-MIBI perfusion tomography, and two-dimensional echocardiography for coronary disease surveillance in a low-prevalence population of heart transplant recipients.
BACKGROUND: Coronary artery disease has been reported to be a significant cause of long-term morbidity and mortality after heart transplantation. However, the diagnosis of coronary disease by means of noninvasive procedures has shown disappointing accuracy, and many centers currently recommend an annual surveillance coronary angiogram. METHODS: We prospectively studied the accuracy and feasibility of a symptom-limited upright bicycle exercise, combined with computerized electrocardiogram analysis, echocardiography, and perfusion scintigraphy in 37 consecutive heart transplant recipients at 2.8 +/- 1.4 years after transplantation for routine follow-up coronary angiography. RESULTS: No patient had any hemodynamically significant (> 50% diameter) coronary stenosis, but luminal irregularities were detectable in four patients. The exercise electrocardiogram was interpretable in only 22 patients (59%), and two of the remaining patients (9%) had false-positive results. The feasibility of perfusion tomography (100%) and two-dimensional echocardiography (97%) were greater than for stress electrocardiogram (p < 0.001 and p < 0.01 respectively). False-positive results were obtained at stress echocardiography in one patient (3%), and at scintigraphy in six patients (16%, p = not significant). None of these methods detected coronary artery stenoses of less than 50% diameter. CONCLUSIONS: Both exercise perfusion tomography and two-dimensional echocardiography are feasible and can be used with adequate specificity for the noninvasive diagnosis of coronary artery disease in heart transplant recipients. However further studies are needed to determine their respective sensitivity.
Coronary Angiography↗