Modeling for policy decisions: potential and problems.

Because decision modeling involves the construction of an explicit, mathematically describable structure of the pertinent elements of a clinical problem, the relative effectiveness of alternative approaches to care can be identified; costly procedures become apparent; new technologies can be assessed in relation to the old in terms of effectiveness and costs; the marginal benefit to be achieved by duplicative or alternative practices can be determined. All of this can be accomplished in terms of patient outcome and without the bias and self-interest of which the profession has been accused. Furthermore, if a resource allocation or reimbursement decision made in the name of cost containment eliminates or limits access to effective diagnostic or therapeutic technologies, the impact of that decision on effective care can be explicitly and quantitatively expressed through decision modeling.

Cost-effective management of patients following myocardial infarction: the impact of ischemia on alternative approaches.

Following uncomplicated myocardial infarction patients are at varying risk for cardiovascular morbidity and mortality. In order to identify and treat high risk patients, various management approaches can be employed. We performed a decision analysis to examine the cost-effectiveness of seven alternative strategies under the assumption that prognosis is affected by both the location of anatomic obstruction and the degree of myocardial ischemia.

Perspectives on clinical decision-making: the application of pattern analysis.

It is the thesis of this presentation that more precise diagnoses and prognostications result when clinical information is analyzed as data-sets or patterns rather than collections of discrete data. Two examples are given in support of the thesis: the classification by computer of QRS complexes in the ambulatory electrocardiogram and the prediction of risk for recurrent ventricular tachycardia. The advantages to be gained from pattern analysis are: (1) significant variables are not preselected and the data are, therefore, unbiased, and (2) nuances in clinical patterns become evident when patients are presented as data-sets.

An editing method for computer-assisted ambulatory ECG review systems.

Editing of computer-assisted ambulatory ECG reviews is critical for accuracy and quantification of the arrhythmias present. This may be time consuming for high arrhythmia content types or tapes with noise interference. A system that combines probit analysis and principle components transformation coupled with maximum likelihood decision theory, through identification of the complexes most subject to classification error in the initial review process and by correcting residual errors automatically, can decrease the number of complexes which need to be overread by a human editor.

The effect of cost containment on the practice of cardiology: predictions.

When health care cost containment is tied to unit pricing, the system may become price-driven rather than care-driven. Although the incentives engendered by unit pricing may not necessarily result in practices detrimental to the young or the patient with relatively pure disease, the potential for adverse effects on the elderly, the poor and the chronically ill is real. Hospitals will soon emphasize quick turnover, efficiency and intensive care.

Digitalis cardiotoxicity.

Clinical manifestations of digitalis toxicity were clearly described by Withering in 1785. One hundred years later, certain digitalis-induced arrhythmias were inscribed on the smoked drum, and shortly thereafter with the introduction of the electrocardiograph, manifestations of digitalis toxicity as recognized today were recorded in animals and human beings. With popularization of the direct-writing electrocardiograph in the late 1940s and the introduction of digitoxin in recommended doses (that in retrospect appear inappropriately high), the documented prevalence of digitalis toxicity increased rapidly.

Behavior of the terminal T wave during exercise in normal subjects, patients with symptomatic coronary artery disease and apparently healthy subjects with abnormal ST segment depression.

The Q-T interval and apex of T wave to end of T wave (aT-eT) interval were measured by computer in four age-matched study groups at rest and during exercise to determine whether: the behavior of the aT-eT interval differs in patients with myocardial ischemia when compared with normal subjects, and the behavior of the aT-eT interval differs in subjects with true positive and false positive ST segment responses. Group I consisted of 57 normal subjects. Group II consisted of 41 symptomatic patients with documented coronary artery disease.

Long QT: good, bad or indifferent?

A survey of current literature suggests an increasing interest in both the desirable and undesirable implications of a prolonged QT interval, the former perceived to be the beneficial effect of antiarrhythmic drugs that prolong the duration of ventricular action potential, and the latter considered to be a potential marker for sudden cardiac death in patients with ischemic heart disease. In addition, there has been an increasing interest in the congenital long QT syndrome associated with an apparent dysfunction of the autonomic nervous system and serious, potentially lethal ventricular arrhythmias. Circumstantial evidence suggests that these arrhythmias are due to increased dispersion of repolarization which may be aggravated by psychologic and emotional perturbations.

Echocardiographic detection of ischemic and infarcted myocardium.

The purpose of this study was to determine the potential of a clinically adaptable two-dimensional echocardiographic system using computer enhancement and a mathematically defined integrated backscatter ratio for the early detection of ischemic and infarcted myocardium. Fifteen dogs had two-dimensional echocardiograms recorded during either open chest coronary occlusion (n = 5), closed chest occlusion (n = 5), occlusion followed by reperfusion (n = 3) or sham coronary occlusion (n = 2). A serial increase in integrated backscatter ratio, representing differences in returned ultrasound intensities between a reference point and specific myocardial regions, was detected between 7 and 12 minutes of complete occlusion in 9 of 12 animals (p less than 0.

Computers and clinical arrhythmias.

Cardiac arrhythmias are ubiquitous in normal and abnormal hearts. These disorders may be life-threatening or benign, symptomatic or unrecognized. Arrhythmias may be the precursor of sudden death, a cause or effect of cardiac failure, a clinical reflection of acute or chronic disorders, or a manifestation of extracardiac conditions.