Biomedical subjects

A Polikaitis

Publications and source records attributed to A Polikaitis.

3 recordsLinked to original sources

PubMed1997

Probability density function revisited: improved discrimination of VF using a cycle length corrected PDF.

The probability density function (PDF) describes the fraction of time an electrogram signal spends at the baseline. In normal rhythm the signal is at baseline during the period between electrogram complexes, while in fibrillation the signal exhibits continuous activity and spends little time at baseline. However, time spent at the baseline is dependent on the rate of the rhythm, which limits the ability of the PDF algorithm to discriminate ventricular fibrillation from fast nonfibrillatory rhythms. A cycle length corrected version of the PDF algorithm has been formulated, which only examines the electrical activity between detected beats. The algorithm was developed utilizing a training set of 77 endocardial recordings and tested utilizing a test set of 90 endocardial and 56 epicardial recordings. Ventricular fibrillation was detected with 100% sensitivity and 98% specificity.

Algorithms↗

PubMed1994

Sensitivity and specificity of a dual-chamber arrhythmia recognition algorithm for implantable devices.

Present ventricular rate-based arrhythmia detection algorithms lack specificity. Using a training set of 109 endocardial electrogram recordings, a sensitive and specific dual-chamber arrhythmia recognition algorithm has been developed. The algorithm uses atrial and ventricular rates, irregularity, degree of beat-to-beat similarity, and measure of electrogram complex distinctiveness to arrive at a diagnostic conclusion. A test set of 121 endocardial electrogram recordings obtained during provocative electrophysiology studies was then used for blinded validation of the algorithm. In normal rhythm, 1:1 tachycardia, atrial tachycardia, atrial flutter, atrial fibrillation, ventricular tachycardia, and ventricular fibrillation, the percentages of sensitivity/specificity were, respectively, 100/99, 100/99, 80/99, 89/98, 91/97, 92/100, and 100/98. Although ventricular rate alone can usually distinguish normal rhythm, ventricular tachycardia, and ventricular fibrillation, it is confounded by atrial arrhythmias and 1:1 tachycardias. When tested on a database, a ventricular rate-only algorithm resulted in sensitivity/specificity of 100/65, 90/78, and 100/99%, respectively, for these three rhythms. Therefore, the dual-chamber algorithm based on both temporal and morphologic measures provides better distinction of normal rhythm and ventricular tachycardia than existing methods, without sacrificing sensitivity.

Arrhythmias, Cardiac↗

PubMed1992

Validation of an adaptive software trigger and arrhythmia diagnostic algorithm.

The authors have developed an algorithm for the identification of arrhythmias using intracardiac atrial and ventricular leads. The algorithm is based on the rate of the depolarizations and a measure of the organization of electrical activity in each of the cardiac chambers. The most important requirement of the algorithm is to identify the occurrence of each cardiac event correctly. A robust amplitude-adaptive software trigger is developed, which accurately detects depolarizations in both chambers. With this reliable trigger the authors demonstrate the veracity of the arrhythmia identification algorithm.

Algorithms↗