Cardiac Arrhythmias–New Considerations

Novel Genomic Approach to the Arrhytmogenic Sudden Cardiac Death (Cardiac Arrhythmias and Genetics) Part 1

Introduction Unfortunately, most of the common diseases in cardiology do not show traditional Mendelian genetics, they usually are complex genetic diseases resulting from the combination of multiple heritable and environmental factors. However, one of the cardiology dysfunction that can affect apparently healthy young adults or with any previous heart disease, such as sudden cardiac death […]

Novel Genomic Approach to the Arrhytmogenic Sudden Cardiac Death (Cardiac Arrhythmias and Genetics) Part 2

Target resequencing strategies For some applications, it would be not necessary to sequence the whole genome, but sequence specific region or regions. This is the case of the study of: i) a disease phenotype previously mapped to a specific region of the genome, ii) candidate genes involve in a pathology or pathway, iii) whole exome. […]

Phenotypic Correlation of Genetic Mutations with Ventricular Arrhythmias (Cardiac Arrhythmias and Genetics) Part 1

Introduction Much progress has been made in identifying genetic loci linked to hereditary arrhythmia syndromes over the past decade and a half. Linkage analyses for Mendelian diseases have been powerful in the discovery phases. Considerable challenges remain however, for the clinician faced with individual patients and families when the clinical symptoms are atypical or intermediate […]

Phenotypic Correlation of Genetic Mutations with Ventricular Arrhythmias (Cardiac Arrhythmias and Genetics) Part 2

Human phenotypic studies Locus-specific triggers While QT interval prolongation puts patients at risk for abnormal heart rhythms, most patients are asymptomatic on a daily basis, with arrhythmias triggered by certain conditions or stimuli. In a 2001 study of 670 patients with known symptomatic LQT1, LQT2, or LQT3, a correlation between genotype and one of three […]

Phenotypic Correlation of Genetic Mutations with Ventricular Arrhythmias (Cardiac Arrhythmias and Genetics) Part 3

Regulation In addition to intrinsic channel defects, there are many regulatory proteins that interact with channels to modulate their activity. Since LQT1 and LQT2 patients often have arrhythmias precipitated by physical or emotional stress, it is important to consider the human stress response affect these channels. The a- and P-adrenergic systems are activated during stress. […]

The Cardiac Ion Channels (Cardiac Arrhythmias) Part 1

Introduction Action potentials are mediated by transient changes in ion conductance across the cell surface membrane. These changes in conductance are primarily mediated by ion channels. Ion channels are membrane-embedded proteins that selectively pass specific ions upon opening. Some ion channels are constitutively open; however, most channels open following stimulation, such as through voltage changes, […]

The Cardiac Ion Channels (Cardiac Arrhythmias) Part 2

Phosphorylation of Nav1.5 Phosphorylation is a well-known regulatory mechanism of ion channels, often resulting in altered biophysical properties. Protein kinase C (PKC) activation provokes a drastic reduction in Nav1.5 current amplitude as well as a negative shift in steady-state inactivation (Qu et al., 1994). This effect is believed to be primarily mediated through the phosphorylation […]

The Pathophysiological Implications of TRP Channels in Cardiac Arrhythmia (The Cardiac Ion Channels) Part 1

Introduction The cardiac arrhythmia is a common cause of morbidity and mortality in the present world, especially in developed countries. The etiology of cardiac arrhythmia is quite broad involving both hereditary and secondary backgrounds. An increasing number of rare but lethal arrhythmogenic mutations have been identified by genome-wide association assays in genes associated with cardiac […]

The Pathophysiological Implications of TRP Channels in Cardiac Arrhythmia (The Cardiac Ion Channels) Part 2

Ca2+dependent arrhythmia Abnormal Ca2+ handling or cycling in cardiac tissues is the main cause for arrhythmia (Ter Keurs & Boyden, 2007). As briefly introduced above, diastolic Ca2+ release (or leak) from the SR is a key event to initiate arrhythmogenic premature depolarizations DAD. Presently, the mechanism whereby DAD is generated by the Ca2+ release can […]

Contributions of Ion Channels in Cardiac Arrhythmias (The Cardiac Ion Channels) Part 1

Introduction The cardiac action potential is arised by the highly orchestrated activity of dozens of ion channel proteins. These transmembrane proteins govern the influx of ion across the sarcolemma of cardiomyocytes generating the ionic currents responsible for excitation. In order to myocardium contract and ensure rhythmic pump function, the long-lasting action potential of the working […]

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