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Certain endocrine disorders such as pheochromocytoma can also cause epinephrine release and can result in tachycardia independent of nervous system stimulation. Hyperthyroidism can also cause tachycardia. [15] The upper limit of normal rate for sinus tachycardia is thought to be 220 bpm minus age. [citation needed]
Sinus tachycardia is a normal response to physical exercise or other stress, when the heart rate increases to meet the body's higher demand for energy and oxygen, but sinus tachycardia can also be caused by a health problem. [4] An elite athlete's heart recorded during a maximum effort workout maintaining over 180 bpm for 10 minutes.
Re-entry is also responsible for most paroxysmal supraventricular tachycardia, and dangerous ventricular tachycardia. These types of re-entry circuits are different from WPW syndromes, which utilize abnormal conduction pathways. Although omega-3 fatty acids from fish oil can be protective against arrhythmias, they can facilitate re-entrant ...
This makes it different from other conditions that generally cause a fast heart rate. The onset of POTS can sometimes begin after other major health events , like pregnancy, surgery, or viral illness.
Obstructive shock is a form of shock associated with physical obstruction of the great vessels of the systemic or pulmonary circulation. [13] Several conditions can result in this form of shock. Cardiac tamponade, in which fluid in the pericardium prevents inflow of blood into the heart (venous return). [9]
Junctional ectopic tachycardia (JET) is a rare tachycardia caused by increased automaticity of the AV node itself initiating frequent heartbeats. On the ECG, junctional tachycardia often presents with abnormal morphology P-waves that may fall anywhere in relation to a regular, narrow QRS complex. It is often due to drug toxicity. [22]
The underlying anatomical causes of PSVT, specifically atrioventricular nodal reentry, involve the presence of two functionally distinct conduction pathways within the AV node and the formation of a reentrant circuit that sustains the tachycardia. [8] These pathways within the AV node are known as the fast pathway and the slow pathway. [9]
Often sinus node dysfunction produces no symptoms, especially early in the disease course. Signs and symptoms usually appear in more advanced disease and more than 50% of patients will present with syncope or transient near-fainting spells as well as bradycardias that are accompanied by rapid heart rhythms, referred to as tachycardia-bradycardia syndrome [4] [5] Other presenting signs or ...