Effects of beta-adrenergic blockade on verapamil-responsive and verapamil-irresponsive sustained ventricular tachycardias.

Abstract

IntroductionTo assess effects of el-adrenergic blockade on ventricular tachycardia (VT) of various mechanisms, electrophysiology studies were performed before and after intravenous infusion of propranolol (0.2 mg/kg) in 33 patients with chronic recurrent VT, who had previously been tested with intravenous verapamil (0.15 mg/kg followed by 0.005 mg/kg/min infusion). In the verapamil-irresponsive group, 10 patients (group IA) had VT that could be initiated by programmed ventricular extrastimulation and terminated by overdrive ventricular pacing, and 11 patients (group IB) had VT that could be provoked by isopro- (5) found that intravenous propranolol slowed the sinus rate but did not affect the VT rate and its inducibility. We and others (6-9), in contrast, observed that intravenous propranolol was effective in suppressing VT inducibility in patients in whom VT was provocable with intravenous infusion of isoproterenol. The disparity in responses to ,B-adrenergic blockade connotes that the occurrence of VT may be accounted for by different electrophysiologic mechanisms.Using the technique of programmed electrical stimulation along with pharmacologic testing with intravenous verapamil, we have previously separated three "presumptive" mechanisms of VT in human beings: reentry, catecholamine-sensitive automaticity, and triggered activity related to delayed afterdepolarizations (10). In the present study, we assessed effects of ,B-adrenergic blockade on these three forms ofVT. Our findings indicate that f3-adrenergic blockade is only specifically effective in suppressing VT suggestive of catecholamine-sensitive automaticity. MethodsPatients. Between July 1983 and July 1986, we studied 33 patients with clinically documented sustained VT that could be reproduced during the course of electrophysiologic evaluation. Sustained VT was defined as VT that lasted longer than 30 s. We excluded patients who were hemodynamically unstable and who had a prior history of congestive heart failure or who had an ejection fraction of < 40% as measured by radionuclide angiography (1 1). All 33 patients had had echocardiography and treadmill exercise testing using the standard Bruce protocol (12) before electrophysiology studies. Additionally, 24 patients had undergone cardiac catheterization with coronary angiography as clinically indicated. There were 22 men and 11 women ranging in ages from 18 to 66 (mean 42.5) yr (Tables I-III). 10 patients had arteriosclerotic heart disease with prior myocardial infarction of > 6 mo, 5 patients had idiopathic cardiomyopathy, and 18 patients had no clinical evidence of structural heart disease. All patients were clinically symptomatic with palpitations, dizziness, and/or syncope. Plasma concentrations ofcatecholamines. In patients with VT provocable with treadmill exercise testing, blood samples were drawn for measurements of plasma epinephrine and norepinephrine levels 1. Abbreviations used in this paper: VT, ventricular

2015 ESC Guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death

“…Idiopatyczny ogniskowy VT z drogi odpływu występuje zwykle u pacjentów bez strukturalnej choroby serca, ale u niektórych pacjentów w CMR wykazano niewielkie nieprawidłowości ścian [547,548]. Mechanizmem ogniskowego powstawania arytmii może być patologiczny automatyzm, micro-reentry lub aktywność wyzwalana [549][550][551][552]. Idiopatyczny VT z RVOT typowo występuje w wieku 20-50 lat, częściej u kobiet [553].…”

“…Wyróżnia się dwie typowe postaci -VT indukowany przez wysiłek fizyczny lub stres oraz powtarzający się jednokształtny VT w spoczynku. Powtarzający się NSVT występuje w 60-92% przypadków, natomiast ustawiczny VT zdarza się sporadycznie [549][550][551][552]. Rzadziej występuje napadowy utrwalony VT rozdzielony długim okresami występowania rzadkich PVC.…”

“…Wiele zupełnie różnych morfologii VT zdarza się bardzo rzadko i nasuwa podejrzenie VT związanego z blizną, jak w przypadku ARVC [535]. Choć idiopatyczny VT z drogi odpływu jest łagodną arytmią, to niekiedy może wystąpić złośliwy VT [551,553]. Elektrokardiogram w czasie rytmu zatokowego jest zwykle prawidłowy, jednak u ok. 10% pacjentów występuje pełny lub niepełny RBBB [554].…”

“…Klinicznie VT z RVOT charakteryzują się mniejszą długo-ścią cyklu i częściej wiążą się z omdleniami niż arytmie z LVOT [550][551][552]. W przypadku typowego VT/PVC z RVOT strefa przejściowa znajduje się dalej (odprowadzenie V4) niż w przypadku VT/PVC z LVOT.…”

Long-term results of catheter ablation of idiopathic right ventricular tachycardia.

“…Nevertheless, a presumptive diagnosis of mechanism may be appropriate based on certain observations.9 The mechanism of VT was classified as reentry if the VT was provocable by programmed stimulation with one to three ventricular extrastimuli and was not suppressed by [10][11][12][13][14][15][16][17][18][19][20] mg i.v. verapamil.9-11 Triggered activity was considered to be the possible mechanism of VT if the VT was inducible by atrial and ventricular pacing at a critical range of cycle lengths and if the induction of VT was suppressed by 10-20 mg verapamil administered intravenously.9-11 The mechanism of VT was considered to be catecholamine-sensitive automaticity if the VT was not provocable by atrial or ventricular pacing or programmed stimulation but was inducible by infusing isoproterenol and if the VT could not be terminated by pacing but was terminated within several minutes after discontinuation of the isoproterenol infusion.9-11…”