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Mechanism of Cardiac Arrhythmias

Mechanism of Cardiac Arrhythmias

Arrhythmias are irregular heart rhythms occurring when the heart's electrical impulses become abnormal. These disturbances can lead to various symptoms, depending on their severity and the underlying cause. Some common factors contributing to arrhythmias include hypoxia, ischemia, electrolyte imbalances, excessive catecholamine exposure, drug toxicity, and muscle overstretching. Arrhythmias can be classified into two main types based on the rate and site of origin of abnormal heart rhythms.

Disturbances in Heart Rhythm

Disturbances in Heart Rhythm

Arrhythmia or dysrhythmia refers to an abnormal heart rhythm caused by a defect in the heart's conduction system. It can cause the heart to beat irregularly, too quickly, or too slowly, leading to symptoms like chest pain, shortness of breath, and fainting. Factors such as stress, caffeine, alcohol, nicotine, cocaine, certain drugs, congenital defects, diseases, and electrolyte abnormalities can trigger arrhythmias.
Arrhythmias are categorized by their speed, rhythm, and origin. A slow heart...

Dysrhythmias VII: Nursing Management of Dysrhythmias

Dysrhythmias VII: Nursing Management of Dysrhythmias

Nursing management of dysrhythmias involves the following:AssessmentSubjective Assessment:The initial step involves gathering patient-reported symptoms such as dizziness, palpitations, and chest discomfort. It is crucial to collect a detailed history, including previous heart conditions, current medication use, and lifestyle factors like caffeine and alcohol consumption.Objective Assessment:This involves observing clinical signs such as jugular venous distention, cool and pale skin, and...

Antiarrhythmic Drugs: Class I Agents as Sodium Channel Blockers

Antiarrhythmic Drugs: Class I Agents as Sodium Channel Blockers

Class I antiarrhythmic drugs are used to treat various types of arrhythmias or irregular heart rhythms. These drugs block the sodium (Na+) channels in the cardiac cells, thereby affecting the movement of electrical impulses across the heart. Class I antiarrhythmic drugs are divided into three subgroups: Class IA, Class IB, and Class IC, each with distinct mechanisms of action and effects on the heart.
Class 1A Antiarrhythmic Drugs: These drugs work by moderately blocking sodium channels,...

Antiarrhythmic Drugs: Class II Agents as β-Adrenergic Blockers

Antiarrhythmic Drugs: Class II Agents as β-Adrenergic Blockers

Adrenergic stimulation generally impacts cardiac rate and rhythm. Specifically, stimulation of the β-adrenoceptors triggers an increase in intracellular calcium ion influx and pacemaker currents, which may cause arrhythmias. Catecholamines like adrenaline also demonstrate β2-adrenoceptor-mediated hypokalemia, impacting cardiac action potential and disrupting the normal cardiac rhythm. Class II antiarrhythmic drugs are β-adrenoceptor antagonists or β-blockers, which indirectly block calcium...

Antiarrhythmic Drugs: Class IV Agents as Calcium Channel Blockers

Antiarrhythmic Drugs: Class IV Agents as Calcium Channel Blockers

Class IV antiarrhythmic drugs, such as verapamil and diltiazem, block calcium channels. They primarily affect the heart, slowing the conduction in calcium-dependent tissues like the SA and AV nodes. These drugs manage reentrant supraventricular tachycardia (SVT) and reduce ventricular rate in atrial flutter/fibrillation.
Verapamil, a calcium channel blocker, inhibits calcium movement across myocardial cell membranes and vascular smooth muscle. This results in the dilation of coronary and...

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Optimization of Transesophageal Atrial Pacing to Assess Atrial Fibrillation Susceptibility in Mice

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Tamoxifen and arrhythmia.

Ladislav Slovacek, Peter Priester, Jiri Petera

Medical Oncology (Northwood, London, England)

|October 22, 2009

Summary

This summary is machine-generated.

Tamoxifen is a widely used breast cancer drug but carries risks like hot flashes and uterine cancer. Clinical trials show no heart benefits and rare arrhythmias, highlighting its side effect profile.

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Area of Science:

Oncology
Pharmacology
Endocrinology

Background:

Tamoxifen is a leading oral selective estrogen receptor modulator for breast cancer treatment.
It is the world's top-selling drug for this indication.

Observation:

Tamoxifen use is associated with various side effects, including hot flashes, menstrual irregularities, and vaginal discharge.
More severe risks include uterine bleeding, endometrial cancer, hypercoagulability, liver steatosis, and thromboembolism.
Long-term clinical trial data indicate a lack of cardioprotective effects and no improvement in serum lipid profiles.

Findings:

While generally well-tolerated, tamoxifen's side effect profile includes significant risks.
Arrhythmia is a very rare adverse event associated with tamoxifen therapy.

Implications:

Understanding tamoxifen's comprehensive side effect profile is crucial for patient management and risk-benefit assessment.
Further research may be needed to explore alternative treatments or strategies to mitigate tamoxifen-related adverse events.
The absence of demonstrated cardioprotective effects warrants careful consideration in patients with cardiovascular risk factors.