Nonsustained ventricular tachycardia was defined in different manners over the years, as 3 to 5 consecutive ventricular premature contractions (whose pacemaker is located below the atrioventricular node), lasting for less than 30 seconds or as more than 16 consecutive ventricular extrasystoles, causing a heart rate above 120 or 125 beats/minute. This poorly reproducible arrhythmia is an overall mortality predictor, especially in patients with structural heart disease.
Nonsustained ventricular tachycardia is usually asymptomatic because of its short duration, but some patients complain about palpitations. It can be recorded at rest in asymptomatic individuals  and it can be a part of the “athlete's heart syndrome” . In trained athletes with no structural heart disease, genetic channelopathies and early repolarization, it is considered to be benign, as it disappears during deconditioning periods . However, the physician must inquire about the use of potentially proarrhythmic drugs and personal and familial history of heart disease, syncope and sudden death .
Longer arrhythmic episodes can cause lightheadedness and anxiety. Syncope, diaphoresis, pallor, hypotension and dyspnea are not usually encountered with nonsustained ventricular tachycardia episodes, but rather with sustained ones. Physical examination may reveal cannon a-waves if atrial fibrillation or flutter is absent and a variation of the first heart sound’s intensity on auscultation. However, these findings are only present during the acute episode, therefore the physician only finds them if he or she examines the patient during those few seconds, so the patient must have already been admitted to a hospital.
Cardiac Signs and Symptoms
The book and DVD package is designed to provide comprehensive coverage of every aspect of cardiovascular medicine from cardiac signs and symptoms and the full range of cardiac imaging techniques through management of peripheral vascular disease and the [books.google.it]
Nonsustained ventricular tachycardia patients must undergo a thorough cardiac evaluation. The most frequent causes of the disease in middle-aged individuals are myocardial ischemia, valve diseases and cardiomyopathies, whereas younger people may suffer from long QT syndrome, arrhythmogenic right ventricular cardiomyopathy or Brugada syndrome.
Blood workup should include potassium, calcium, magnesium and phosphate evaluation, as well as measurement of serum digoxin and tricyclic antidepressants levels or toxicology screening where appropriate. Cardiac troponins should also be measured when acute myocardial ischemia is suspected.
A simple electrocardiogram is able to pinpoint the approximate location of the ventricular contractions and to describe the tachycardia as monomorphic or polymorphic. The location of the R/S transition may predict the presence of arrhythmogenic right ventricular cardiomyopathy , whereas the duration of the cardiac cycle during the episode is an indicator of concomitant polymorphic ventricular tachycardia . Holter monitoring is usually indicated in symptomatic patients and accurately describes arrhythmic episodes . Further information is added by electrophysiology testing. In patients where arrhythmic episodes can be induced, the mortality risk is higher .
Some episodes are exercise-induced and may be caused by ventricular outflow arrhythmias . Right ventricular outflow ectopic loci cause a left bundle branch block pattern, whereas those located in the left ventricle outflow tract appear as right bundle branch block complexes. Structural abnormalities of these areas can be demonstrated by magnetic resonance imaging or myocardial biopsy  .
Echocardiography is another useful tool, as it is able to describe myocardial scars (visualized as akinetic regions), left ventricular hypertrophy (an indicator of long-term hypertension) and the presence and severity of valvulopathies. Cardiomegaly also predicts nonsustained ventricular tachycardia episodes . If the arrhythmia is detected during the recovery period of an exercise test, it indicates cardiovascular mortality during the next decades .
Wide QRS Complex
Wide QRS Complex Tachycardias. Med Clin North Am. 2001 Mar; 85(2): 245-66. Gupta AK. Wide QRS Complex Tachycardias. Med Clin North Am. 2001 Mar; 85(2): 245-66. [wikem.org]
Class I antiarrhythmic drugs, tricyclic antidepressants and hyperkalemia may also cause very wide QRS complexes. [ecgwaves.com]
Andries A new approach to the differential diagnosis of a regular tachycardia with a wide QRS complex Circulation, 83 (1991), pp. 1649-1659 [4.] G.F. Van Hare, P. [analesdepediatria.org]
Depending on the etiology, onset of ventricular tachycardia can be paroxysmal (sudden) or nonparoxysmal, its wide qrs complexes can be uniform or polymorphic, and the ventricular beating may be independent of the atrial beating (av dissociation). [icd10data.com]
Wide QRS complexes ( 120 ms). Presence of AV dissociation. Fusion beats. Retrograde ventriculoatrial conduction may occur, which can generate an ECG complex similar to PSVT with aberrant conduction. [patient.info]
T Wave Alternans
We examined whether T-wave alternans (TWA) level is correlated with nonsustained ventricular tachycardia (NSVT) incidence in association with PCI in patients with acute ST-segment elevation myocardial infarction (STEMI). [ncbi.nlm.nih.gov]
Alternans T-wave alternans (TWA) is a test that is thought to reflect dispersion of repolarization and has been shown to predict VT inducibility and future arrhythmic events better than SAECG. 101 In patients similar to those in MADIT II, a microvolt [clinicalgate.com]
Promising results on the predictive ability of T-wave alternans tests have not been consistent (90–92). [onlinejacc.org]
Signal-averaged ECG, baroreflex sensitivity, heart rate variability, and T-wave alternans were not helpful for arrhythmia risk stratification. [academic.oup.com]
However, chronic, high-intensity exercise sometimes has harmful effects on cardiac health, and pathologic changes, such as myocardial fibrosis, have been observed in endurance athletes. [ncbi.nlm.nih.gov]
Theoretical and experimental studies identified reduced repolarization reserve, increased myocardial fibrosis, and elevated cytosolic Ca levels that promote EADs as mechanisms triggering tachyarrhythmias [23–28]. [hindawi.com]
In another report, NSVT, but not myocardial fibrosis, was an independent predictor of arrhythmic events and death (130). [onlinejacc.org]
HYPOTHESIS: Provided that early and intensive lipid-lowering treatment can reduce ventricular premature beat or non-sustained ventricular tachycardia after ACS. [ncbi.nlm.nih.gov]
When NSVT occurs in patients with normal hearts, it usually has a benign prognosis. Therefore, establishing the presence or absence of structural or inherited heart disease is a critical step in each patient's evaluation. [ncbi.nlm.nih.gov]
Unclear Valvular Disease Mechanism High incidence in AS, severe MR (25%) Mechanical stress from dysfunctional valvular apparatus Management Beta-blockade if symptomatic Prognosis No evidence that NSVT is an independent predictor of SCD. [ddxof.com]
This article reviews the supporting evidence for the therapeutic options available for these patients according to the etiology of the reduced ejection fraction. [ncbi.nlm.nih.gov]
Ambulatory* Female Humans Male Middle Aged Prevalence Retrospective Studies Risk Assessment Tachycardia, Ventricular/diagnosis* Tachycardia, Ventricular/epidemiology Tachycardia, Ventricular/etiology Time Factors [ncbi.nlm.nih.gov]
Background Definition 3-5 consecutive beats originating below the AV node Rate 100bpm Duration 30s Patient remains hemodynamically stable Epidemiology Occurs in 0-4% of ambulatory patients Increased frequency in males and with increasing age Clinical [wikem.org]
Given the epidemiology of SCD, the normal EF group is an extremely desirable target for intervention. However, in the MERLIN TIMI-36 clinical trial population, even the highest risk group had a SCD rate of only 4.3% at one year. [ahajournals.org]
Cardiovascular Magnetic Resonance and XRay Computed Tomography 245 Choosing Appropriate Imaging Techniques 269 DISORDERS OF RHYTHM AND CONDUCTION 283 Electrophysiology of Cardiac Arrhythmias 285 Treatment of Cardiac Arrhythmias 305 Syncope 329 HEART FAILURE 345 Pathophysiology [books.google.com]
However, indi vi duals with out these recogni zed traits and conditions also develop OSA making the etiology and pathophysiology unclear. [umu.se]
Pathophysiology of Heart Disease (3rd ed.). Lippincott Williams & Wilkins. ISBN 978-0-7817-4027-2. G. Morris, Innasimuthu A L, J.P. Fox, R.A. [en.wikipedia.org]
The sympathetic nervous system in heart failure physiology, pathophysiology, and clinical implications. [scielo.br]
These results support the need for ICD implantation for primary prevention, with attention to careful programming of the detection rate to prevent inappropriate therapy. [ncbi.nlm.nih.gov]
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