SUMMARY Ventriculo-atrial conduction and the reentry phenomenon was studied during right ventricular and bundle of His pacing in the intact dog heart. Bipolar electrogram recordings were obtained from the sinus node, Bachman's bundle, the right and left atria, the bundle of His, and the ventricle. Retrograde conduction resulted in a specific change in the sequence of atrial activation. The reco...

Rationale: Nkx2.5 is one of the most widely studied cardiac-specific transcription factors, conserved from flies to man, with multiple essential roles in both the developing and adult heart. Specific dominant mutations in NKX2.5 have been identified in adult congenital heart disease patients presenting with conduction system anomalies and recent genome-wide association studies implicate the NKX...

Nuclear thyroid hormone (T3) receptors (TR) play a critical role in mediating the effects of T3 on development, differentiation and normal physiology of many organs. The heart is a major target organ of T3, and recent studies in knockout mice demonstrated distinct effects of the different TR isoforms on cardiac function, but the specific actions of TR isoforms and their specific localization in...

Specialized fiber electrograms were recorded in 64 patients during open-heart surgery. Intervals were measured from the proximal His bundle, distal His bundle, and right and left bundle branches to the earliest QRS deflection in the limb lead ECG (pH-Q, dH-Q, RB-Q, and LB-Q interval, respectively). There was an increase of pH-Q intervals with increasing age such that at age 3 months the normal ...

DURING the repair of congenital defects of the venitricular septum, various disturbances of cardiac function may occur.1'Permanent complete heart block has been the most serious of these disturbances. Right bundle-branch block seems benign. Inereased knowledge of the anatomic features of the atrioventricular (AV) conduction system has resulted in surgical technics that have nearly eliminated co...

Introduction: Endorphins are produced by cardiomyocytes, and exert different effects on the heart. The aim of the present study is to assess morphine effects on extracellular atrioventricular (AV) node field potential pattern and ventricular rhythm of isolated rabbit heart during experimental atrial fibrillation (AF). Methods: Effects of different concentrations of morphine (10, 20, 50 and 1...

The endothermic state of mammals and birds requires high heart rates to accommodate the high rates of oxygen consumption. These high heart rates are driven by very similar conduction systems consisting of an atrioventricular node that slows the electrical impulse and a His-Purkinje system that efficiently activates the ventricular chambers. While ectothermic vertebrates have similar contraction...

DURING the repair of congenital defects of the venitricular septum, various disturbances of cardiac function may occur.1'Permanent complete heart block has been the most serious of these disturbances. Right bundle-branch block seems benign. Inereased knowledge of the anatomic features of the atrioventricular (AV) conduction system has resulted in surgical technics that have nearly eliminated co...

In the last few years, transcatheter aortic valve implantation (TAVI) has become an alternative procedure in patients with severe aortic stenosis and high risk for surgical aortic replacement. Due to the anatomic correlation between aortic valve structure and conduction system of the heart, one of the most common complications after TAVI is conduction system disturbances which including bundle ...

the coronary slow flow phenomenon (csfp) is characterized by a delayed coronary blood flow in the absence of an obstructive coronary artery disease. although the relation between the csfp and myocardial ischemia has been reported previously, there is no knowledge about the relationship between the csfp and the conduction system disorder. in this case report, we describe a patient with the csfp ...