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Cardiac Arrythmias
Published in Charles Theisler, Adjuvant Medical Care, 2023
An arrythmia refers to any change from the normal sequence of electrical impulses that affects either the rate or rhythm of the heartbeat. Irregular heartbeats such as atrial fibrillation, bradycardia, tachycardia, conduction disorders, rhythm disorders, ventricular fibrillation, and premature contractions are arrythmias, also known as dysrhythmias. Palpitations are disturbances in the rhythm that can be felt and can make the heart feel like it is beating too hard or too fast, skipping a beat, or fluttering. Symptoms and signs of arrhythmia often include chest pain, dizziness, breathlessness, palpitations, fainting, chest fluttering, tachycardia or bradycardia, and shortness of breath. Arrythmia is the most common cause of sudden cardiac arrest. There are a wide variety of causes for arrythmias, such as myocardial infarction, coronary heart disease (CAD), hypertension (HTN), thyroid problems, drug abuse, diabetes, certain medications, etc. Smoking and excessive alcohol or caffeine use also increase the risk of an arrythmia.
Anesthesia Monitoring and Management
Published in Michele Barletta, Jane Quandt, Rachel Reed, Equine Anesthesia and Pain Management, 2023
Use of an ECG is requisite for definitive diagnosis of arrhythmias. AV block is normal in horses and may be observed while under anesthesia, especially in the presence of alpha-2 agonists (Figure 7.8). The most common pathologic arrhythmia observed in horses is atrial fibrillation and is commonly identified peri-anesthetically.Ventricular premature complexes (VPCs) are sometimes seen in systemically ill patients.Supraventricular premature complexes are occasionally seen in anesthetized horses, and they may precede atrial fibrillation.Foals with uroabdomen suffering from hyperkalemia may exhibit bradycardia, VPCs, sinus arrest, asystole, and/or ventricular fibrillation.
Drugs in pregnancy and lactation
Published in Evelyne Jacqz-Aigrain, Imti Choonara, Paediatric Clinical Pharmacology, 2021
Evelyne Jacqz-Aigrain, Imti Choonara
Fetal supraventricular tachyarrythmias with normal cardiac anatomy are estimated to complicate the course of 1/10 000 pregnancies. The diagnosis, the mechanism and the tolerance of the arrhythmia can be evaluated by M. Mode and Doppler echocardiography. The prognosis is dependent on the cardiac function and risk of cardiac failure, the mechanism of the arrhythmia and the response to treatment.
Focus on cardiac rhythm disorders
Published in Acta Cardiologica, 2023
Patrizio Lancellotti, Caroline Piette
Myocardial ischaemia is a common cause of arrhythmia, and the potential mechanism of ischaemic arrhythmia is quite complex and diverse. At present, in animal experiments, arrhythmia models can be constructed through a variety of methods, which are associated with high scientific research costs, high technical difficulty, complicated operation, low survival rate of the experimental animals, and poor reproducibility. Guo et al. showed in a rat model that the combination of subcutaneous and intraperitoneal injections of isoproterenol is more likely to induce arrhythmia than a single injection route [9]. Differential diagnosis of broad QRS tachycardia with left (L) BBB morphology is broad. The analysis of its response to adenosine can allow to make a correct diagnosis. The acceleration of tachycardia with disappearance of LBBB can indicate the presence of an accessory pathway (AP) on the ipsilateral side. However, this is not a phenomenon one would expect as a response to adenosine, which would most likely terminate such tachycardia [10]. Frequent junctional beats occurring in bigeminy are extremely rare. In very unusual situations, these ectopies may be responsible for a retrograde, but also an anterograde block, leading to a pseudo paroxysmal atrioventricular bloc [11, 12].
Gene therapy to terminate tachyarrhythmias
Published in Expert Review of Cardiovascular Therapy, 2022
Kohei Kawajiri, Kensuke Ihara, Tetsuo Sasano
Gene therapy targeting cardiac arrhythmias has been studied for many years, but few clinical applications have been made. Currently, the most commonly used treatments for cardiac arrhythmia are antiarrhythmic drugs, ablative therapy, and implantable devices. Antiarrhythmic drugs, which have been studied for a long time, have shown some efficacy in treating tachyarrhythmias [1]. Ablative therapy is making progress and is particularly effective in treating paroxysmal and early stage of supraventricular arrhythmias [2]. Implantable devices are used to prevent sudden death [3,4]. However, it is difficult to treat all arrhythmias effectively with these therapies [5]. In particular, persistent atrial fibrillation (AF), which is often encountered in daily practice, is difficult to treat using the methods listed above [6], and the treatment of catheter ablation or antiarrhythmic drugs may lead to iatrogenic arrhythmias [7–9]. Once implanted, Implantable Cardioverter-Defibrillators (ICDs) are effective in preventing sudden death from ventricular tachycardia (VT) and ventricular fibrillation (VF), but it is difficult to treat the arrhythmia itself and suppress its onset. It can also cause device infections in the long term [10].
Clinical electrophysiology of the aging heart
Published in Expert Review of Cardiovascular Therapy, 2022
Kyle Murray, Muizz Wahid, Kannayiram Alagiakrishnan, Janek Senaratne
Palpitations are a heightened or uncomfortable awareness of heartbeat and are a common reason for elderly patients to present to a clinic or hospital [34]. Palpitations are divided into cardiac and noncardiac causes. Noncardiac causes are further subclassified into psychosomatic, medical illness, and pharmacologic mediated. Cardiac causes are secondary to arrhythmias (e.g. tachyarrhythmia, bradyarrhythmia, and extrasystoles) and structural heart disease (e.g. valvular disease, heart failure, and hypertrophic cardiomyopathy). In adults presenting to emergency with palpitations, 47% of cases are a cardiac cause [35]. Patients who are elderly, male, have irregular palpitations, palpitations lasting >5 minutes, and history of coronary artery disease (CAD) have a high likelihood of a cardiac cause [24].