Suppression of Ventricular Tachyarrhythmias by Transvenous Intracardiac Pacing after Acute Myocardial Infarction

Abstract

MBITALUSHUALing the dose of bronchodilator drug which reaches the bronchi. This problem was not of course resolved by the use of IPPV, which merely ensured that about the same volume of aerosol was delivered to the bronchi whatever drug or concentration was used. It is probable, however, that the average dose of isoprenaline received by the patients in this particular study was relatively large, because the increase in heart rate (29 per minute) produced by a 0.5°/,, concentration given for three minutes by IPPV was much greater than that produced by 1,000 ug. of isoprenaline administered by pressurized dispenser (13 per minute) in a previous study reported by Choo-Kang et al. (1969) on a similar group of patients. The average dose of salbutamol received by the patients must have been equally large when a 0-50/0 concentration was used, but it caused a much smaller increase in heart rate.IPPV has the capability, which a pressurized dispenser lacks, of delivering an adequate dose of bronchodilator aerosol to dyspnoeic patients. Such patients are often unable to inhale more than a small proportion of a single dose of aerosol from a pressurized dispenser, and this may partly account for the poor response of patients with status asthmaticus to bronchodilator drugs administered in that way. Furthermore, when the technique of IPPV is used, the drug is administered in a high concentration (40 0/% or more) of oxygen, and if the studies in experimental animals with isoprenaline reported by Collins et al. (1969) are applicable to man this may reduce considerably the potential cardiotoxic hazards associated with the use of bronchodilator aerosols.Though it cannot, of course, be assumed that a concentration of salbutamol which does not produce tachycardia is ipso facto less likely to provoke more serious cardiac side effects, it would seem reasonable, when powerful bronchodilatation is required, to select a form of treatment which does not increase the heart rate, and which at the same time ensures adequate oxygenation. These requirements can substantially be met by the administration of a 0.5 % aerosol of salbutamol by IPPV in 40% oxygen for a period of three minutes.

Accelerated Sinus Rhythm Prevents Catecholaminergic Polymorphic Ventricular Tachycardia in Mice and in Patients

“…This occurred despite the fact that catecholamine-induced HR increase initially is accompanied by progression of ventricular arrhythmia complexity. 2 Although it is well recognized that ectopic ventricular automaticity can be reset by overdrive pacing, 31–33 it is still unexpected that sinus tachycardia could provide sufficient protection against clinical CPVT. A possible explanation is that the positive chronotropic effect of β adrenergic stimulation during stress could paradoxically counterbalance the triggered activity simultaneously promoted by β-adrenergically induced SR Ca overload.…”

Reversion of ventricular tachycardia by pacemaker stimulation.

“…The majority required pacing after the initial return to sinus rhythm in order to suppress ventricular premature beats. We have found that pacing in this way is effective in the suppression of recurrent ventricular tachyarrhythmias (Bennett and Pentecost, 1970), and the ability to correct or control recurrent ventricular tachycardia developing either during or after pacing is a useful extension of the technique. It does not require general anaesthesia and avoids the hazards of high energy electrical cardioversion (Lown,Amarasingham,and Neuman,I962), an important consideration when recurrent ventricular tachycardia requires repeated cardioversion in a patient with an already damaged myocardium.…”

“…Rapid transvenous pacing of the heart is of value in stabilizing the cardiac rhythm when recurrent episodes of ventricular tachycardia and fibrillation persist in spite of conventional drug treatment (Swedberg and Malm, I964;Sowton, Leatham, and Carson, I964;Friedberg, Lyon, and Donoso, 1970;Bennett and Pentecost, 1970). Ventricular tachycardla may, however, return after cessation of pacing or even during the manoeuvre.…”

Stepwise ablation strategy for post–myocardial infarction ventricular fibrillation: From arrhythmia suppression to ablation

“…The patient was quickly fitted with a right ventricular temporary pacemaker lead and overdrive pacing in the right ventricle with 100 beats/min was performed to suppress ventricular arrhythmias. 7 , 8 , 9 Transient loss of ventricular capture or a decrease in pacing rates both led to an almost immediate VF recurrence. An urgent VF ablation procedure was planned the next day.…”