Comparison of ambulatory electrocardiography and exercise testing

Health-enabling technologies for pervasive health care: on services and ICT architecture paradigms

BACKGROUND

Progress in information and communication technologies (ICT) is providing new opportunities for pervasive health care services in aging societies.

OBJECTIVES

To identify starting points of health-enabling technologies for pervasive health care. To describe typical services of and contemporary ICT architecture paradigms for pervasive health care.

METHODS

Summarizing outcomes of literature analyses and results from own research projects in this field.

RESULTS

Basic functions for pervasive health care with respect to home care comprise emergency detection and alarm, disease management, as well as health status feedback and advice. These functions are complemented by optional (non-health care) functions. Four major paradigms for contemporary ICT architectures are person-centered ICT architectures, home-centered ICT architectures, telehealth service-centered ICT architectures and health care institution-centered ICT architectures.

CONCLUSIONS

Health-enabling technologies may lead to both new ways of living and new ways of health care. Both ways are interwoven. This has to be considered for appropriate ICT architectures of sensor-enhanced health information systems. IMIA, the International Medical Informatics Association, may be an appropriate forum for interdisciplinary research exchange on health-enabling technologies for pervasive health care.

Normal tension glaucoma: the value of predictive tests

Fifty-four normal tension glaucoma cases were studied to determine the value of several clinical tests for predicting the progression of the disease. Outflow facility, intraocular pressure (IOP) increase after water drinking, and diurnal changes in IOP were studied. Progression was determined on the basis of changes in visual sensitivity as measured on the Octopus 201. A minimum of four examinations of the central 30 degrees were conducted over a 3- to 7-year period. Progression of visual field defects was seen in 38.5% of eyes that had demonstrated some degree of abnormality in at least one of three clinical tests, while only 10.7% of those eyes that appeared normal on the basis of these tests showed such progression. The difference was significant (p < 0.04). These results suggest that the three clinical tests may be of value in detecting normal tension glaucoma eyes at risk for progression of visual field defects.

Sudden death risk in overt coronary heart disease: the Framingham Study

Over 30 years of surveillance of 5127 subjects free of CHD, 760 men and 574 women developed overt CHD, and there were 160 sudden deaths in men and 73 in women. Among those who sustained clinically manifest CHD, the sudden death risk was increased 6.7 times that of those without an interim event. Although the relative risk was comparable in the two sexes, CHD did not eliminate the female advantage over men. Myocardial infarction imposed a greater sudden death risk than angina pectoris, and silent infarctions were as dangerous as symptomatic infarctions. Onset of CHD put young and old at equal risk of sudden death. Some 40% of sudden deaths occurred in the 4% of the general population with overt CHD. The proportion of coronary attacks presenting as sudden death increased from 13% at ages 35 to 64 years to 20% at ages 65 to 94 years. The fraction of CHD deaths classified as sudden deaths was lower in those with than without interim CHD. In those with established CHD, factors reflecting ischemic myocardial damage and cardiac failure were the chief predictors of sudden death. The proportion of CHD deaths presenting as sudden deaths has not declined in subjects with prior CHD over three decades, despite a national decline in the overall CHD mortality rate.

Incremental prognostic power of clinical history, exercise electrocardiography and myocardial perfusion scintigraphy in suspected coronary artery disease

The incremental ability of a clinical history, exercise electrocardiography (ECG) and myocardial perfusion scintigraphy to identify coronary events in the year after testing was assessed in 1,659 patients with symptoms suggestive of coronary artery disease (CAD), 74 of whom suffered a coronary event in the year after testing. Prognostic power was quantified in terms of the area under receiver operating characteristic curves derived from logistic regression. In 1,451 patients with normal rest ECG findings, a clinical history alone provided the most prognostic power (area = 72%). This improved significantly (by 5%) only when both tests were analyzed. In contrast, clinical history had significantly less prognostic power in the 208 patients with abnormal rest ECG findings (area = 58%), but each test then provided a significant incremental improvement in these patients (by 14% for each). A strategic model was thereby developed for prognostic assessment that recognizes the incremental power of these tests in specific patient groups as well as their overall accuracy and monetary cost. This strategy stratified individual patient risk for subsequent coronary events over a full order of magnitude (from 2 to 22%) at a 64% reduction in the cost of testing compared to performing both stress tests in all patients.

Myocardial ischemia during daily activities and stress

Twenty-four-hour, 2-channel Holter monitoring during daily activities was performed in 210 patients; during the same day a Bruce protocol treadmill test was also performed and the electrocardiogram was recorded using the same Holter system. Significant ST-segment depression was observed during daily activities in 97 patients, while similar changes were recorded during the treadmill test in 122 patients. Thus, 77% of patients with ST depression during the provocation of the treadmill test had ischemic episodes during their everyday life. On the other hand, 3 patients with proven significant coronary artery disease had spontaneous ischemic episodes during daily activities, but had a negative stress test. The ischemic changes during daily activity developed at a lower heart rate than during stress testing (94 beats/min vs 109 beats/min, respectively, p less than 0.05). A total of 351 ischemic episodes were recorded during daily activities, 241 (69%) of these were asymptomatic. In 46 patients all episodes were asymptomatic, in 15 all were symptomatic, while in 36 both symptomatic and silent episodes were detected. The mean duration of the symptomatic episodes was 13.7 minutes and that of the asymptomatic ones was 14.9 minutes (difference not significant). The degree of ST depression in these 2 groups was also similar. Because of more advanced symptomatology in 143 patients, coronary arteriography was performed; 43 had normal and 100 had pathologic coronary arteries. In this selected group, the sensitivity of Holter monitoring during daily activity was 87% and during stress 97%; the specificity during daily activity was 95% and during stress 88%.(ABSTRACT TRUNCATED AT 250 WORDS)

Mitral valve prolapse: definition and implications in athletes

Mitral valve prolapse is probably the most common cardiac valve disorder, affecting approximately 5% of the population. Although it is genetically determined, its clinical manifestations do not usually become evident before adulthood. In the setting of a cardiology referral center, a mitral valve prolapse syndrome, consisting of nonspecific symptoms, repolarization changes on the electrocardiogram and arrhythmias, has been identified. However, doubt has recently been expressed about the existence of such a syndrome. The prognosis of mitral valve prolapse is generally favorable but infrequent complications do occur and include transient ischemic attacks, progression of mitral regurgitation with or without ruptured chordae tendineae, infective endocarditis and sudden death. The symptoms and the complications are not usually related to physical activity. A permissive attitude toward participation of patients with mitral valve prolapse in competitive athletics is probably warranted; however, it would appear reasonable to disqualify athletes with mitral valve prolapse in the following circumstances: history of syncope; disabling chest pain; complex ventricular arrhythmias, particularly if induced or worsened by exercise; significant mitral regurgitation; prolonged QT interval; Marfan's syndrome; and family history of sudden death.

An ambulatory ventricular function monitor: validation and preliminary clinical results

A device for the continuous measurement of left ventricular (LV) function was tested in a series of 34 subjects. The instrument consisted of 2 arrays of radiation sensitive cadmium telluride detectors held in place over the region of the left ventricle and lung by a vest-like garment (hence the name VEST). The VEST electronic instrumentation included analog-to-digital converters, a battery pack, microprocessor and gating device, which were worn in a back pack. Data generated by the VEST, including the digitized average electrocardiogram, RR interval, counts/13 ms in each radiation detector, and time since commencement of data recording, were recorded on a cassette tape recorder every 2 minutes for subsequent analysis. At the conclusion of conventional multigated blood pool imaging, the VEST was positioned and worn by the subjects while supine, standing in place and walking. The correlation of ejection fraction calculated independently from the VEST and scintillation camera data was greater than 0.95. The inter-record reproducibility of the ejection fraction measured by the VEST in sedentary subjects was less than 3%.

Proximal left anterior descending coronary heart disease and complex ventricular arrhythmias

In this study, 87 consecutive patients with angiographically proven coronary artery disease (CAD, stenosis greater than 75%) underwent 24-h Holter monitoring, 76 of them having had transmural myocardial infarction, a mean of five months before evaluation. Of the total, 51 patients showed single-vessel disease, in 31 (61%) of them with involvement of the left anterior descending (LAD) artery. In 26 patients with proximal LAD stenosis or occlusion and usually large aneurysms and subsequently impaired left ventricular function relatively low prevalence of significant ventricular premature contraction (VPC, Lown greater than or equal to III) was seen. On the contrary in 19 patients with multivessel disease and proximal LAD stenosis advanced forms of VPCs were present in 63% (p less than 0.01). Further both groups differed significantly in the frequency of postinfarction angina (30% vs. 100%; p less than 0.001) and their incidence in positive exercise stress tests (15% vs. 84%; p less than 0.001). Ejection fractions were comparable in both groups (mean 45% vs. 52%). Finally 17 patients with multivessel disease but without proximal LAD lesion did not differ in any of the above mentioned parameters, when compared to the patients with single-vessel disease and proximal LAD stenosis. We conclude that impaired left ventricular function does not sufficiently explain the high risk of sudden death in postmyocardial infarction patients. The coronary and functional status of the surviving myocardium has to be taken into consideration as well.