Left-to-right ventricular (LV/RV) differences in repolarization have been implicated in lethal arrhythmias in animal models. Our goal is to quantify LV/RV differences in action potential duration (APD) and APD rate adaptation and their contribution to arrhythmogenic substrates in the in vivo human heart using combined in vivo and in silico studies. Electrograms were acquired from 10 LV and 10 R...

In normal cardiac myocytes, the action potential duration (APD) is several hundred milliseconds. However, experimental studies showed that under certain conditions, APD could be excessively long (or ultralong), up to several seconds. Unlike the normal APD, the ultralong APD increases sensitively with pacing cycle length even when the pacing rate is very slow, exhibiting a sensitive slow rate-de...

Action potential duration (APD) restitution properties and repolarization alternans are thought to be important arrhythmogenic factors. We investigated the role of intracellular calcium (Ca2+i) cycling in regulating APD restitution slope and repolarization (APD) alternans in patch-clamped rabbit ventricular myocytes at 34 to 36 degrees C, using the perforated or ruptured patch clamp techniques ...

We have studied the effect of 3-amino-1-hydroxypropylidene-1,1-bisphosphonate (APD) on the morphology of rat bone and the metastatic behavior of Walker 256 (W256) cancer cells in the rat skeleton. Male Fischer rats (150-175 g) received s.c. injections for 7 days with APD (0.5 mg/kg body weight/day) (+ APD; n = 20) or with vehicle (-APD; n = 20). Subsequently, 10 + PD and 10 -APD rats received i...

Objectives: Recently, we have demonstrated that abdominal paracentesis drainage (APD) benefits patients with acute pancreatitis (AP). However, the therapeutic efficacy of APD against AP-associated lung injury remains unclear. Methods: Consecutive patients with fluid collections (≥100 ml) in the abdominal or pelvic cavity, who were admitted to our hospital within 48 h of the onset of AP, were in...

AIMS The atrial potential duration (APD) restitution has been suggested to play an important role in ventricular fibrillation; however, its role in atrial fibrillation (AF) has not been determined. This study sought to investigate the APD restitution properties in two different AF models: vagally mediated AF and 6-h rapid atrial pacing-induced AF. METHODS AND RESULTS Twenty anaesthetized open...

OBJECTIVE Cardiac repolarization is prolonged and repolarization reserve (RR) is diminished in female rabbits and humans, compared to males. Reduced RR is evidenced by the relatively greater increase in ventricular action potential duration (APD) in myocytes from females in response to drugs that block repolarizing K(+) currents. Mice are an increasingly important experimental model animal for ...

BACKGROUND An action potential duration (APD) restitution curve with a steep slope ≥1 has been associated with increased susceptibility for malignant ventricular arrhythmias. We aimed to evaluate the "restitution hypothesis" and tested ventricular APD restitution slope as well as effective refractory period (ERP)/APD ratio for long-term prognostic value in patients with ischemic (ICM) or dilate...

OBJECTIVES The authors sought to study mechanisms to explain why single premature atrial complexes (PACs) from the pulmonary veins (PVs) may initiate human atrial fibrillation (AF). BACKGROUND Theoretically, single PACs may initiate AF if the rate response of action potential duration (APD) restitution has a slope >1. However, human left atrial APD restitution and its relationship to AF have ...