New methods for the analysis of heartbeat behavior in risk stratification

Abstract

Developing better methods for risk stratification for tachyarrhythmic sudden cardiac remains a major challenge for physicians and scientists. Since the transition from sinus rhythm to ventricular tachycardia/fibrillation happens by different mechanisms in different people, it is unrealistic to think that a single measure will be adequate to provide a good index for risk stratification. We analyze the dynamical properties of ventricular premature complexes over 24 h in an effort to understand the underlying mechanisms of ventricular arrhythmias and to better understand the arrhythmias that occur in individual patients. Two dimensional density plots, called heartprints, correlate characteristic features of the dynamics of premature ventricular complexes and the sinus rate. Heartprints show distinctive characteristics in individual patients. Based on a better understanding of the natures of transitions from sinus rhythm to sudden cardiac and the mechanisms of arrhythmia prior to cardiac arrest, it should be possible to develop better methods for risk stratification.

Keywords: cardiac arrhythmias; early after depolarization; non-linear dynamics; parasystole; sudden cardiac death; ventricular tachycardia.

Figure 1

Rhythm strips (A) and heartprint (B) for a male patient with unknown clinical history. Heartprint shows sinus rates with NN intervals between 0.5 and 1 s, the number of intervening beats between two ectopic beats (NIB) were mostly 0, 1 and 3, and the coupling interval (CI) was relatively fixed. Case 44 from the PhysioNet Sudden Cardiac Death Data Base (Goldberger et al., 2000). For abbreviations, see text.

Figure 2

Rhythm strip (A) and the heartprint (B) for an 80-year-old male patient with unknown clinical history. Heartprint shows that NN intervals were between 0.4 and 0.8 s with a wide range of NIB values and coupling interval (CI) was highly variable. Case 48 from the PhysioNet Sudden Cardiac Death Data Base (Goldberger et al., 2000).