Acute pulmonary hypertension secondary to right ventricular pacing in a patient with sinus node dysfunction and severe ischemic cardiomyopathy.

Right ventricular pacing has been associated with worsening symptoms of heart failure in patients with cardiomyopathy. We describe a patient with severe ischemic cardiomyopathy and sinus node dysfunction who developed acute worsening of pulmonary hypertension immediately after right ventricular pacing.

Wenckebach's periods or alternating Wenckebach's periods during 4:1 atrioventricular block?

This article deals with the tracings of a patient having episodes of atrial flutter with 4:1 atrioventricular (AV) block increasing to 8:1 AV block. This phenomenon was attributed to the coexistence of 3-level block due to transverse dissociation with 2:1 AV block in the most proximal level, or first level as well as in the second level coexisting with a Wenckebach's period in the most distal, or third level. It is suggested that perhaps the term Wenckebach's periods during progression of 4:1 AV block best describes this arrhythmia so as to maintain the term alternating Wenckebach's periods only to those occurring when 2:1 block increases to higher degrees of AV block.

Pacemaker diagnostics: a critical appraisal of current technology.

Diagnostic information retrieved from a pacemaker offers the ability to improve patient care. Pacemaker diagnostic data provides information regarding pacemaker function and activity, lead function, arrhythmia occurrence, and data to aid in optimal pacemaker programming. Current pacemakers incorporate greater storage capabilities, more efficient means of storing and presenting data between follow-up visits, and more options for programming diagnostic functions and algorithms. The cardiac rhythm of the paced patient can be evaluated via real-time intracardiac electrograms at interrogation, surface electrocardiograms, ambulatory electrocardiograms, and by pacemaker stored diagnostic function that may include stored intracardiac electrograms. This article focuses on the various methods of obtaining diagnostic information regarding pacemaker activity, pacemaker function, and diagnostic information on cardiac arrhythmias. The current clinical applicability and limitations of these methods and the use of stored diagnostic data in the clinical follow-up and study of patients with pacemakers is discussed.

Differences in the activation patterns between sustained and self-terminating episodes of human ventricular fibrillation.

BACKGROUND: Experimental studies have suggested that R-R interval dynamics during ventricular fibrillation (VF) have organized features, but whether dynamic behavior of non-sustained VF differs from sustained VF is unknown. AIM: The purpose of this study was to investigate whether the dynamics of R-R intervals during non-sustained VF differs from the dynamics during sustained VF. METHODS: A group of 67 patients undergoing routine implantable cardioverter defibrillator (ICD) testing was studied. Forty-three VF events containing mean of 38 local cardiac activation intervals before the termination by ICD shock were analyzed. From intracardiac electrogram recordings, the ratio between the short and long term variability (SD1/SD2) and fractal scaling exponent (alpha) were analyzed. After the initial analyses, data sets were randomized and reanalyzed. Local activation dynamics were then also compared in seven patients with both sustained and spontaneously terminating VF episodes. RESULTS: Randomization caused a change in the VF dynamics from organized toward less organized dynamics (alpha) from 1.08 +/- 0.57 to 0.81 +/- 0.45, P < 0.05 and SD1/SD2 from 0.80 +/- 0.23 to 1.04 +/- 0.20, P < 0.01). Spontaneously terminating VF showed more organized dynamics than sustained VF terminated by shock (P < 0.05). CONCLUSIONS: Local cardiac activation dynamics during initial phase of human VF shows organized dynamics. Spontaneously terminating VF episodes have more structured dynamics than sustained VF. Thus, the dynamic behavior of local cardiac activation intervals may be related to the maintenance of ventricular tachyarrhythmias.