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Biomedical subjects

P L Tilkemeier

Publications and source records attributed to P L Tilkemeier.

8 recordsLinked to original sources
PubMed1997

Multimedia image display: a view to the future.

The development of multimedia image review stations offers the cardiologist the ability to review multiple image sets in a single setting rather than moving from one review station to another. To accomplish this goal there are three essential barriers: 1) memory requirements for digital images; 2) standardization of data format; and 3) practical user interfaces. Image compression algorithms can be used to overcome the digital barrier; however, these must be used cautiously so as to not adversely affect image quality. The lack of standardization is being addressed by the implementation of the Digital Communication in Medicine (DICOM) standard, and practical user interfaces are being developed every day with the widespread implementation of World Wide Web technology. These solutions will allow the clinician to review all of a patient's image data in one location, such as in the office, on the nursing unit, or at home.

Computer Communication Networks↗
PubMed1996

The role of noninvasive testing in evaluating patients for coronary artery disease.

Risk stratification of patients with coronary artery disease using noninvasive imaging techniques has become increasingly more important in the cost-conscious delivery of patient care. This is evidenced by significant developments involving both nuclear cardiology and echocardiography for the assessment of viability, silent myocardial ischemia and prognosis, as well as the emergence of new techniques, in particular the use of positron emission tomography isotopes with single photon emission computed tomography cameras and low-dose dobutamine echocardiography in the detection of viability. New developments regarding screening for and the clinical importance of silent myocardial ischemia as well as new developments regarding classification of radionuclide perfusion defects and stress echocardiograms that portend a poor prognosis are also reviewed. Finally, new techniques and stress agents have been development that add to the choices available to the clinician for the optimal assessment of the patient being considered for revascularization.

Coronary Disease↗
PubMed1992

Influence of exercise intensity on the presence, distribution, and size of thallium-201 defects.

The effects of two levels of exercise intensity on the size and location of thallium-201 defects were compared in 22 patients with known ischemic coronary artery disease. A symptom-limited incremental exercise test was performed followed (greater than 48 hours) by submaximal steady-state exercise at 70% of the peak heart rate achieved during the incremental test. Planar thallium-201 myocardial scans obtained after each protocol were analyzed by means of both visual qualitative and computerized quantitative methods. After incremental exercise all patients exhibited reversible thallium-201 defects, and submaximal exercise still resulted in reversible defects in 20 (91%) patients. However, the size of the ischemic area and the degree of ischemia were significantly reduced by both qualitative and quantitative criteria after submaximal exercise. Therefore interpretation of thallium-201 scans with regard to severity of disease and prognosis should take into account exercise intensity.

Blood Pressure↗
PubMed1991

Comparison of chest pain, electrocardiographic changes and thallium-201 scintigraphy during varying exercise intensities in men with stable angina pectoris.

This study was performed to evaluate the presence of angina pectoris, electrocardiographic changes and reversible thallium-201 defects resulting from 2 different levels of exercise in 19 patients with known coronary artery disease and evidence of exercise-induced ischemia. The exercise protocols consisted of a symptom-limited incremental exercise test (Bruce protocol) followed within 3 to 14 days by a submaximal, steady-state exercise test performed at 70% of the maximal heart rate achieved during the Bruce protocol. The presence and time of onset of angina and electrocardiographic changes (greater than or equal to 0.1 mV ST-segment depression) as well as oxygen uptake, exercise duration and pressure-rate product were recorded. Thallium-201 (2.5 to 3.0 mCi) was injected during the last minute of exercise during both protocols, and the images were analyzed using both computer-assisted quantitation and visual interpretations. Incremental exercise resulted in anginal symptoms in 84% of patients, and electrocardiographic changes and reversible thallium-201 defects in all patients. In contrast, submaximal exercise produced anginal symptoms in only 26% (p less than 0.01) and electrocardiographic changes in only 47% (p less than 0.05), but resulted in thallium-201 defects in 89% of patients (p = not significant). The locations of the thallium-201 defects, when present, were not different between the 2 exercise protocols. These findings confirm the sequence of the ischemic cascade using 2 levels of exercise and demonstrate that the cascade theory is applicable during varying ischemic intensities in the same patient.

Angina Pectoris↗
PubMed1990

Prognostic value of predischarge low-level exercise thallium testing after thrombolytic treatment of acute myocardial infarction.

Low-level exercise thallium testing is useful in identifying the high-risk patient after acute myocardial infarction (AMI). To determine whether this use also applies to patients after thrombolytic treatment of AMI, 64 patients who underwent early thrombolytic therapy for AMI and 107 patients without acute intervention were evaluated. The ability of both the electrocardiogram and thallium tests to predict future events was compared in both groups. After a mean follow-up of 374 days, there were 25 and 32% of cardiac events in the 2 groups, respectively, with versus without acute intervention. These included death, another AMI, coronary artery bypass grafting or angioplasty with 75% of the events occurring in the 3 months after the first infarction. The only significant predictors of outcome were left ventricular cavity dilatation in the intervention group and ST-segment depression and increased lung uptake in the nonintervention group. The sensitivity of exercise thallium was 55% in the intervention group and 81% in the nonintervention group (p less than 0.05). Therefore, in patients having thrombolytic therapy for AMI, nearly half the events after discharge are not predicted by predischarge low-level exercise thallium testing. The relatively weak correlation of outcome with unmasking ischemia in the laboratory before discharge may be due to an unstable coronary lesion or rapid progression of disease after the test. Tests considered useful for prognostication after AMI may not necessarily have a similar value if there has been an acute intervention, such as thrombolytic therapy.

Electrocardiography↗
PubMedDate not supplied

Neuropsychological functioning among cardiac rehabilitation patients.

PURPOSE: The underlying pathophysiology contributing to coronary heart disease also predisposes patients to cerebrovascular disease and associated cognitive disorders. Although prior studies have focused on the neuropsychological sequelae of specific cardiac problems, few have examined the associated cognitive capacities and limitations of typical cardiac patients. The current study was designed to examine neuropsychological functioning among a sample of cardiac rehabilitation (CR) patients. METHODS: Using neuropsychological instruments, patients were compared in a CR program to age-matched outpatient control subjects who had no known history of cardiac or neurologic disease. Cardiac rehabilitation patients were then divided into dichotomous subgroups based on whether they had undergone coronary artery bypass grafting, had experienced a myocardial infarction, had hypertension, or had impaired ejection fraction. Neuropsychological functioning was examined relative to each of these factors. RESULTS: Cardiac rehabilitation patients had poorer neuropsychological test performance than did control subjects, with subtle relative deficits on measures of response generation, memory, and verbal abstraction, and particularly verbal fluency. Low ejection fraction, hypertension, and prior coronary artery bypass graft were associated with greater relative neuropsychological impairments. CONCLUSIONS: Although CR patients were not grossly neuropsychologically impaired as a group, it appears highly likely that many within a given program exhibit some degree of neuropsychological dysfunction. Including neuropsychological screening as part of pre-CR testing would help to identify such patients. This information may help staff to impart health care information in a manner that is most effective for the individual patient and may also be useful in the formation of realistic goals.

Aged↗