A supraventricular tachycardia ( SVT ) is a rapid rhythm of the heart in which the origin of the electrical signal is either the atria or the AV node . ventricular premature beats. There are no normal-looking QRS complexes.Sometimes only a few such beats occur together, and then the heart returns to a normal rhythm Ventricular tachycardia is defined as three or more beats of ventricular origin in succession at a rate greater than 100 beat minute Specific types of SVT include atrial fibrillation, AV nodal re-entrant tachycardia, and Wolff-Parkinson-White syndrome. However, other underlying causes may be present, such as congestive heart failure, sepsis, or methylxanthine toxicity. The effect of MAT on the heart conduction system may or may not lead to hemodynamic instability. Ventricular tachycardia is a condition where the heart rate in the large lower pumping chambers of the heart (called the ventricles) is fast (between 120 - 200 beats a minute). The ventricles then contract to push the blood out of the heart into the blood vessels of your lungs and the rest of your body. antitachycardia pacing techniques or electrical cardioversion. Nonsustained ventricular tachycardia suggests that the episodes are short (three beats or longer) and terminate spontaneously. However, SVT becomes a problem when it occurs frequently or lasts for long periods of time and produces symptoms. Common symptoms associated with SVT include palpitations, light headedness, and chest pain. SVT may also cause confusion or loss of consciousness.
Ventricular tachycardia is a rapid heart beat initiated within the ventricles, characterized by 3 or more consecutive premature ventricular beats. This is in contrast to ventricular tachycardias , which are tachycardias that are not dependent on the atria or AV node. A capture beat occurs at a shorter RR interval than the RR interval of the VT. AV conduction also may occur simultaneously with depolarization of the ventricular focus. MAT most often is found in the elderly patient with decompensated chronic lung disease and should be thought of as a hypoxic complication of underlying heart conduction pathology. Ventricular tachycardia that lasts more than 30 seconds is called sustained ventricular tachycardia. Sustained ventricular tachycardia usually occurs in people with structural heart disease that damages the ventricles. The SA node, the natural pacemaker of the heart, starts the electrical signals and transmits them to the AV node. Patients who have ventricular tachycardia in the absence of coronary artery disease have other cardiac abnormalities, including cardiomyopathy, mitral valve prolapse, valvular heart disease, QT interval prolongation and, in an otherwise normal heart, an abnormality described as primary electrical instability. Most commonly, it occurs weeks or months after a heart attack. It is more common among older people. Ventricular tachycardia may be a complication of underlying coronary heart disease, but it is also found in otherwise healthy people.
Causes of Tachycardia
The common Causes of Tachycardia :
- Pulmonary emboli, or blood clots migrating into the lung arteries from elsewhere in the body
- Heart failure
- Drinking too much caffeine in coffee, tea, or soft drinks
- Exposure to heart stimulants, such as caffeine, tobacco, or alcohol
- Ventricular tachycardia is a potentially lethal disruption of normal heartbeat ( arrhythmia ) that may cause the heart to become unable to pump adequate blood through the body.
- Myocardial infarction
- Damage or microscopic abnormalities in the muscles of the atria (upper heart chambers)
Symptoms of Tachycardia
Some are common Symptoms of Tachycardia :
- Light-headedness or dizziness
- Chest pain or tightness
- Shortness of breath
- A slow heartbeat
- A racing heartbeat
- The sensation of your heart pounding in your chest
- Fainting (syncope) or near fainting
Treatment of Tachycardia
Here is the list of the methods for treating Tachycardia :
- Ventricular tachycardia may become an emergency situation and may be require CPR , electrical defibrillation or cardioversion (electric shock), or intravenous anti-arrhythmic medications (such as lidocaine, procainamide, bretylium, or sotalol).
- Provide oxygen, cardiac monitoring, and pulse oximetry.
- They include radiofrequency ablation (delivery of energy of a specific frequency through an electrode catheter inserted in the heart) and open-heart surgery. When magnesium sulfate is administered to correct hypokalemia, most patients convert to normal sinus rhythm (NSR).
- For emergency care of patients with ventricular tachycardia, intravenous medications or defibrillation (an electric shock) must be delivered immediately to restore a normal heart rhythm.
- In recent years, a preferred treatment for many chronic (long-term) ventricular tachycardias consists of implanting a device called implantable cardioverter defibrillator (ICD).
- The diving reflex causes peripheral vasoconstriction and a vagally mediated decrease in cardiac output.