Search results
Author(s):
Moinuddin Choudhury
,
Mark R Boyett
,
Gwilym M Morris
Added:
3 years ago
The sinoatrial or sinus node (SAN) is the heart’s natural pacemaker. Located in the superior right atrium, it automatically produces cyclical electrical activity to initiate each heartbeat in normal sinus rhythm. SAN dysfunction (SND) in humans, also known as ‘sick sinus syndrome’, can manifest as pathological bradycardia and asystolic pauses. As a result, SND can lead to symptoms of reduced…
View more
Author(s):
Dario DiFrancesco
Added:
3 years ago
HCN4 (hyperpolarisation-activated, cyclic nucleotide gated 4) channels, the pore-forming α–subunits of ‘funny’ channels originally described in pacemaker cells of the sinoatrial node (SAN),1 are responsible for the early phase of diastolic depolarisation in these cells and are key determinants of pacemaker generation and control of heart rate.2–5 HCN4 channels are selectively expressed in the SAN…
View more
Author(s):
Mahmoud Abdelnabi
,
Ashraf Ahmed
,
Abdallah Almaghraby
,
et al
Added:
3 years ago
Ivabradine is a pure heart rate-lowering agent best characterised by its negative chronotropic effect on the sinoatrial node.1 Its unique mechanism selectively blocks the pacemaker funny (If) channels, which are responsible for spontaneous depolarisation in the sinoatrial node that regulates heart rate during sinus rhythm (Figure 1).2 Since 1980, it has been well established that controlling the…
View more
Author(s):
Sharon A George
,
N Rokhaya Faye
,
Alejandro Murillo-Berlioz
,
et al
Added:
3 years ago
More than 100years have passed since the atrioventricular node (AVN) was first discovered by Sunao Tawara1 and described as a “Knoten” of tissue located at the proximal end of the Bundle of His (BoH).2 Despite the numerous advances in knowledge regarding the structure and function of the AVN, there are still several controversies that need to be addressed in both clinical and scientific settings…
View more
Author(s):
Demosthenes G Katritsis
Added:
3 years ago
Since the identification of the hyperpolarisation-activated cyclic nucleotide channel 4 (HNC4), a major constituent of the pacemaker current (If) in the sinoatrial node, as a modulator of heart rate,1 several genetic causes of sinus bradycardia by means of mutations in ion channel encoding genes have been described. They may result in isolated sick sinus sydrome or other arrhythmia and…
View more
Author(s):
Gareth DK Matthews
,
Andrew Grace
Added:
3 years ago
The use of adenosine in cardiology is ubiquitous. From arrhythmia to coronary intervention to cardiac imaging, adenosine is an essential part of everyday practice because of its widespread effects on electrophysiology and the coronary vasculature. Electrophysiologists will be most familiar with adenosine for its use in terminating supraventricular tachycardias (SVTs) that are dependent on the…
View more
Author(s):
Zhao Liu
,
J Kevin Donahue
Added:
3 years ago
In the United States, atrial fibrillation (AF) is the most common sustained cardiac arrhythmia affecting approximately six million patients and contributing to a greatly increased risk of stroke, heart failure (HF) and overall morbidity and mortality.1,2 The prevalence of AF is increasing as the average age of the population increases.3,4
Currently available therapies for AF are suboptimal…
View more
Author(s):
Konstantinos D Rizas
,
Wolfgang Hamm
,
Stefan Kääb
,
et al
Added:
3 years ago
Experimental and clinical studies have demonstrated that enhanced sympathetic autonomic nervous system (SANS) activity can destabilise myocardial repolarisation,1–4 increasing vulnerability to developing fatal cardiac arrhythmias.5–8 Accordingly, assessment of SANS activity has always been a major goal for cardiac risk stratification methods. Various non-invasive methods including assessment of…
View more
Author(s):
Boris Rudic
,
Rainer Schimpf
,
Martin Borggrefe
Added:
3 years ago
Short QT syndrome (SQTS) is a rare, inheritable channelopathy of the heart characterised by abnormally short QT intervals on the electrocardiogram (ECG) and an increased propensity to develop atrial and ventricular tachyarrhythmias in the absence of structural heart disease.1,2 SQTS was first described as a new clinical entity by Gussak et al. in 2000.1 Until then shortening of the QT interval…
View more
Author(s):
Cristina E Molina
,
Jordi Heijman
,
Dobromir Dobrev
Added:
3 years ago
Optimal cardiac function depends on appropriate rate and force of contraction, with specific cardiac regions having developed particular beat-to-beat properties depending on their individual functions. For example, isovolumetric contraction time is shorter in the right ventricle (RV) than in the left ventricle (LV). At the cellular level, cardiac function is regulated by regional cardiomyocyte…
View more