ventricular tachycardia(redirected from Vtach)
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Ventricular tachycardia (V-tach) is a rapid heart beat that originates in one of the lower chambers (the ventricles) of the heart. To be classified as tachycardia, the heart rate is usually at least 100 beats per minute.
A rapid heart rate can originate in either the left or right ventricle. Ventricular tachycardia which lasts more than 30 seconds is referred to as sustained ventricular tachycardia. A period of three to five rapid beats is called a salvo, and six beats or more lasting less than 30 seconds is called nonsustained ventricular tachycardia. Rapid ventricular rhythms are more serious than rapid atrial rhythms because they make the heart extremely inefficient. They also tend to cause more severe symptoms, and have a much greater tendency to result in death.
Although generally considered to be among the life-threatening abnormal rhythms, harmless forms of sustained V-tach do exist. These occur in people without any structural heart disease.
Causes and symptoms
Most ventricular tachycardias are associated with serious heart disease such as coronary artery blockage, cardiomyopathy, or valvular heart disease. V-tach is often triggered by an extra beat originating in either the right or left ventricle. It also occurs frequently in connection with a heart attack. V-tach commonly occurs within 24 hours of the start of the attack. It must be treated quickly to prevent fibrillation. After 48 to 72 hours of the heart attack, the risk of ventricular tachycardia is small. However, people who have suffered severe damage to the larger anterior wall of the heart have a second danger period, because V-tach often occurs during convalescence from this type of heart attack.
Sustained ventricular tachycardia prevents the ventricles from filling adequately so the heart can not pump normally. This results in loss of blood pressure, and can lead to a loss of consciousness and to heart failure.
The individual with V-tach almost always experiences palpitation, though some episodes cause no symptoms at all.
Diagnosis is easily made with an electrocardiogram.
Any episode of ventricular tachycardia that causes symptoms needs to be treated. An episode that lasts more than 30 seconds, even without symptoms, also needs to be treated. Drug therapy can be given intravenously to suppress episodes of V-tach. If blood pressure falls below normal, a person will need electric cardioversion ("shock") immediately.
With appropriate drug or surgical treatment, ventricular tachycardia can be controlled in most people.
A person susceptible to sustained ventricular tachycardia often has a small abnormal area in the ventricles that is the source of the trigger event. This area can sometimes be surgically removed. If surgery is not an option, and drug therapy is not effective, a device called an automatic cardioverter-defibrillator may be implanted.
Atrial — Having to do with the upper chambers of the heart.
Cardiomyopathy — A disease of the heart muscle.
Cardioversion — A electrical shock delivered to the heart to restore a normal rhythm.
Coronary artery — The artery that supplies blood to the heart muscle itself.
Electrocardiogram — A visual representation of the heart beat.
Fibrillation — Rapid, uncoordinated, quivering of the heart.
Palpitations — Uncomfortable feeling of the heart beat in the chest.
Valvular — Having to do with the valves inside the heart.
American Heart Association. 7320 Greenville Ave. Dallas, TX 75231. (214) 373-6300. http://www.americanheart.org.
abnormally rapid heart rate, usually taken to be over 100 beats per minute. adj., adj tachycar´diac.
antidromic circus movement tachycardia a supraventricular tachycardia supported by a reentry circuit that uses the atrioventricular node in the retrograde direction and an accessory pathway in the anterograde direction; this produces a broad QRS rhythm indistinguishable from ventricular tachycardia. Such a tachycardia may also use two accessory pathways (one anterograde and one retrograde) and not involve the AV node at all.
atrial tachycardia a rapid heart rate, between 140 and 250 beats per minute, with the ectopic focus in the atria and with no participation by the atrioventricular node or the sinoatrial node. It is recognizable on the electrocardiogram because the P wave precedes the QRS complex, as opposed to being merged with it or following it. This condition is usually associated with atrioventricular block or digitalis toxicity.
benign ventricular tachycardia tachycardia originating in the ventricles, not associated with structural heart disease or significant hemodynamic symptoms.
bidirectional ventricular tachycardia (bifascicular ventricular tachycardia) a ventricular arrhythmia characterized by heart rates of 90 to 160 beats per minute, alternating right and left axis deviation, ectopic focus that alternates between the anterior superior and posterior inferior fascicles, and a right bundle branch block pattern in lead V1; seen in digitalis toxicity and other conditions.
chaotic atrial tachycardia an ectopic atrial tachycardia due to multifocal activity, characterized by at least three different shapes of P waves on the electrocardiogram; often associated with chronic obstructive lung disease.
circus movement tachycardia (CMT) a reentry circuit that uses an accessory pathway or pathways; there are two subtypes, antidromic and orthodromic circus movement tachycardia.
ectopic tachycardia rapid heart action in response to impulses arising outside the sinoatrial node.
junctional tachycardia rhythm at the rate of 100 to 140 beats per minute that arises in response to impulses originating in the atrioventricular junction, i.e., the atrioventricular node. It is often seen with digitalis toxicity and is due to triggered activity, but it may also be due to altered automaticity. In the case of digitalis toxicity, the term may be used to encompass the entire span of junctional rates with this condition, i.e., approximately 70 to 140 beats per minute.
monomorphic ventricular tachycardia a type that has a uniform beat-to-beat QRS morphology.
nonsustained ventricular tachycardia a type that terminates spontaneously within 30 seconds and does not lead to hemodynamic collapse.
orthodromic circus movement tachycardia a supraventricular tachycardia supported by a reentry circuit that uses the atrioventricular node in the anterograde direction and an accessory pathway in the retrograde direction, producing a narrow QRS complex.
orthostatic tachycardia disproportionate rapidity of the heart rate on arising from a reclining to a standing position.
paroxysmal tachycardia rapid heart action that starts and stops abruptly.
paroxysmal atrial tachycardia paroxysmal supraventricular tachycardia.
paroxysmal supraventricular tachycardia (PSVT) a narrow QRS tachycardia that begins and ends abruptly; it may be terminated with a vagal maneuver. It has two common mechanisms, atrioventricular nodal reentry and circus movement that uses the atrioventricular node anterogradely and an accessory pathway retrogradely. On the electrocardiogram it is characterized by abrupt onset, and mechanisms are differentiated by the relation of the P wave to the QRS complex.
polymorphic ventricular tachycardia a type that has a constantly, and sometimes subtly, changing beat-to-beat QRS configuration.
potentially malignant ventricular tachycardia a type that is not associated with structural heart disease or hemodynamically important cardiac symptoms but is sometimes associated with left ventricular dysfunction.
sinus tachycardia (ST) a rapid rhythm originating in the sinoatrial node with a rate of usually 100 to 160 beats per minute; conduction through the ventricles is normal. During exercise or stress this is normal, but if it occurs during rest it is abnormal.
sustained ventricular tachycardia tachycardia that lasts more than 30 seconds and leads to hemodynamic collapse.
ventricular tachycardia an abnormally rapid ventricular rhythm with aberrant ventricular excitation, characterized by at least three consecutive ventricular complexes of more than 100 beats per minute. It is generated within the ventricle and is most often associated with atrioventricular dissociation.
paroxysmal tachycardia originating in an ectopic focus in the ventricle.
See also: torsade de pointes.
See also: torsade de pointes.
tachycardia of at least three consecutive ventricular complexes with a rate greater than 100 beats/min. It usually originates in a focus distal to the branching of the atrioventricular bundle.
ventricular tachycardiaV tach, wide-complex tachycardia Cardiology A common, potentially life threatening abnormal rapid–160–240 beats/minheart beat initiated in the ventricles, characterized by 3 or more consecutive premature ventricular beats; VT may compromise systemic pumping of blood Triggers Spontaneous, post-acute MI, cardiomyopathy, mitral valve prolapse, myocarditis, post-heart surgery, antiarrhythmics, ↓ potassium, pH–acid-base changes, ↓ O2 Types Nonsustained–eg, lasting < 30 secs, sustained, > 30 secs. See Torsade de pointes.
ven·tric·u·lar tach·y·car·di·a(ven-trik'yū-lăr tak'i-kahr'dē-ă)
A heart rate exceeding 100 beats per minute driven by an ectopic ventricular focus.
ventricular tachycardiaA dangerous disorder of heart rhythm in which the contraction of the lower main pumping chambers is initiated from uncontrolled electrical impulses arising in the ventricles instead of in the SINOATRIAL NODE. The heart rate is abnormally fast-between 140 and 220 beats per minute and this may persist for hours or days and progress to severe HEART FAILURE and death. Treatment is by the use of drugs such as lignocaine (lidocaine) to regulate the rate or by electrical DEFIBRILLATION.
abnormally rapid heart rate.
rapid contraction of the atrium arising from an ectopic focus in the atrium. The heart rate remains normal.
rapid heart action in response to impulses arising outside the sinoatrial node.
one occurring as a compensation for a sinus bradycardia and A-V block.
that arising in response to impulses originating in the atrioventricular junction, i.e. the atrioventricular node.
disproportionate rapidity of the heart rate on arising from a recumbent to a standing position.
episodes of an abrupt and marked increase in heart rate in a resting patient, with an equally sudden return to normal.
sinus tachycardia, simple tachycardia
an increase in heart rate from heightened activity of the sinoatrial node, such as occurs with excitement or pain.
a combination of junctional tachycardia and atrial tachycardia.
see ventricular tachycardia.
pertaining to a ventricle.
ventricular assist device
a circulatory support device consisting of a pump with afferent and efferent conduits attached to the left ventricular apex and the ascending aorta, respectively, each conduit containing a porcine valve to ensure unidirectional blood flow; the pump rests on the external chest wall and is connected to an external pneumatic power source and control circuit.
folds of mucosa, parallel and craniolateral to the vocal cords. Called also false vocal cords, vestibular folds.
double right ventricular outlet
a cardiac anomaly rarely seen in animals in which both the aorta and pulmonary artery arise from the right ventricle and there is a defect in the ventricular septum.
excessive ventricular moderator bands
a rare syndrome of cardiomyopathy in cats caused by an excessive number of moderator bands in the left ventricle, extending from the papillary muscles to the ventricular septum.
see ventricular extrasystole.
see ventricular fibrillation.
ventricular function curve
see starling curves.
see ventricular hypertrophy.
ventricular outflow obstruction
flow of blood from the ventricles is impaired by lesions or congenital abnormalities in the outflow tract. This is usually associated with hypertrophy of the ventricle and can be demonstrated with echocardiography or contract radiography. Left outflow obstruction occurs with stenosis and other anomalies of the aorta; right outflow obstruction occurs with pulmonic stenosis, pulmonic insufficiency, tetralogy of Fallot, and double-chambered right ventricle.
ventricular premature contraction (VPC)
see premature heartbeats.
due to focal weakness causes sudden death due to cardiac tamponade.
ventricular septal defect
a congenital heart defect in which there is persistent patency of the ventricular septum in either the muscular or fibrous portion most often due to failure of the bulbar septum to completely close the interventricular foramen. The defect permits flow of blood directly from one ventricle to the other, bypassing the pulmonary circulation and producing varying degrees of cyanosis because of oxygen deficiency. Its clinical characteristics also include a systolic murmur and a palpable thrill on both sides of the chest, dyspnea and poor exercise tolerance. The occurrence is sporadic except that it is inherited in goats and dogs.
the muscular wall between the ventricles. A small section, between the aortic vestibule and the right atrium, is membranous. Failure of the septum to close completely during fetal growth causes a septal or subaortic defect.
ventricular shortening fraction
in echocardiography, the percentage change in diameter from diastole to systole. Calculated from the internal systolic and diastolic dimensions. It is a measure of mycocardial function.
ventricular slice method
a method for examination of fixed heart by cutting it into 0.5 inch thick slices, perpendicular to the plane of the ventricular septum, from apex to base. Useful in examination of myocardial lesions and cardiomyopathy.
is manifested by a high heart rate with or without arrhythmia. In both cases there is severe cardiac disease and often acute heart failure.