Complete heart block implies an absolute independence between atria and ventricles that does not in fact always exist. Segers showed that, after complete block was artificially produced in the frog's heart, atria and ventricles would sometimes begin to beat exactly in phase, most commonly in a 2 to 1 ratio. He subsequently reported one clinical example of 2 to 1 A-V synchronization in a patient...

Complete heart block implies an absolute independence between atria and ventricles that does not in fact always exist. Segers showed that, after complete block was artificially produced in the frog's heart, atria and ventricles would sometimes begin to beat exactly in phase, most commonly in a 2 to 1 ratio. He subsequently reported one clinical example of 2 to 1 A-V synchronization in a patient...

BACKGROUND Different atrial arrhythmias can coexist in the recipient and donor atria after heart transplantation. CASE PRESENTATION We report an unusual case of a patient with three different types of atrial arrhythmia after heart transplantation: an atrial fibrillation in the recipient atria, and a cavotricuspid isthmus dependent atrial flutter and a focal atrial tachycardia in the donor atr...

Vasoactive intestinal polypeptide (VIP) is implicated in the modulation of vagal effects on the heart rate. In this study, the impact of acute and chronic atropine administration on VIP levels in rat heart atria was investigated in relation to heart rate in the course of vagus nerves stimulation. Anaesthetised control and atropinised (10 mg/kg/day for 10 days) rats pretreated with metipranolol ...

The influence of sympathetic innervation on the growth and intrinsic rate of beating established by fetal rat heart was studied by culturing fetal atrial tissue in sympathetically innervated and denervated anterior eye chambers of adult Sprague-Dawley rats. One anterior eye chamber in each host rat was sympathetically denervated by removing the ipsilateral superior cervical ganglion. In oculo, ...

The rhythmic contraction of our heart is controlled by electrical impulses that travels throughout the cardiac muscle. signal generated sinus node, which can be thought as natural pacemaker heart. This impulse spreads from its initiation in SA node atria through specialized internodal pathways, to atrial myocardial contractile cells and atrioventricular node.This term paper reviews anatomy Acti...

To localize the areas of the cardiopulmonary region involved in tonic inhibition of the vasomotor center, anesthetized dogs were subjected to sinoaortic denervation and diaphragmatic vagotomy. Afferent vagal nerve traffic was interrupted in the neck by cooling. With the venous return taken from the venae cavae, oxygenated extracorporeally, and returned to the aorta, the heart was removed, leavi...

Depression is associated with increased risk of coronary heart diseases. Selective serotonin reuptake inhibitors (SSRIs) have been proved to be very effective in normalizing symptoms of depression, but the data on possible influence of these drugs on cardiovascular function is controversial. Applying Taqman RT-PCR assay, the effect of chronic treatment with a SSRI antidepressant fluoxetine has ...

BACKGROUND Nitric oxide (NO) synthesized within sinoatrial cells recently has been shown to participate in the autonomic control of heart rate. We hypothesized that NO in the neuronal cells in the heart was increased and parasympathetically regulated heart rate after myocardial infarction (MI). METHODS AND RESULTS We examined heart rate dynamics and neuronal NO synthase (nNOS) expression and ...

As specialized compartments of the heart, the atria feature unique mechanical and structural properties that differ considerably from those of the ventricular myocardium. Beyond their contribution to cardiac output as a reservoir, conduit, and booster pump at different phases of the cardiac cycle, the atria determine heart rhythm, regularity, and rate (chronotropy). They also function as mechan...