Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3849_Библиотеки_им_академика_М_И_Перельмана

all major device companies. iATP is a feature which gives customized ATP in real time in some device companies. An iATP algorithm delivers the equivalent of a train of Burst pulses (S1) followed by 1 (S2) or 2 (S2-S3) extra- stimuli Ramp+ pulses. The protocol for the rst iATP sequence is S1-S2. If the rst sequence does not terminate the tachyarrhythmia, the protocol for the sub­sequent sequences is S1-S2 or S1-S2-S3. If patients are hemody­namically stable and manual ATP to be performed, it is recommended that patients receive sedation as delivery of ATP can result in the degeneration of ventricular tachycardia to ven­tricular brillation requiring emergent ICD or external electrical shock. Of concern is the patient that presents with incessant VT or frequent, dened as >3 episodes of VT within 24hours, termed VT storm often requiring multiple shocks and acute inpatient admission for management accompanied by a signicant rise in both inpatient and short term mortality [11]. The management of all of these patients is similar with a few exceptions made for the VT storm patient. In general, recurrent antitachycardia pacing or lone outpatient ICD shocks should result in the initiation or accel­eration of antiarrhythmic drug therapy starting with sotalol or amiodarone followed by the addition of mexiletine if necessary. It is also important to make sure that these patients are adequately beta blocked since the majority of ischemic VT’s are going to pos­sess an adrenergic component and be benecially treated with beta blockade. Catheter ablation for ventricular tachycardia has traditionally been viewed as a last resort or palliative treatment for ventricular arrhythmias. However, with signicant developments in mapping systems, improvement in diagnostic and therapeutic ablation catheters, along with the ability to hemodynamically sup­port patients with mechanical circulatory support, catheter abla­tion for VT are being utilized earlier in the treatment course of patients. Hence, it is reasonable to consider VT ablation instead of initiation of antiarrhythmic medication in the management of these patients even following rst VT event. Once patients experi­ence recurrent ICD therapies for VT while on an appropriate anti­arrhythmic drug regimen, ventricular tachycardia ablation should absolutely be considered.

The management of VT storm patients is more difcult and varied than the ambulatory cardiomyopathy patients with recur­rent ATP or lone ICD shocks for ventricular tachycardia. VT storm patients present with recurrent ICD shocks often are accom­panied by hemodynamic instability. The rst step in their manage­ment is to establish control of their ventricular rhythm. Intravenous antiarrhythmic agents are utilized acutely to achieve this with both amiodarone and lidocaine used commonly. Although limited by toxicity, lidocaine can be a useful agent especially if there are concerns for ongoing ischemia. However, a combination of amiodarone (or sotalol) and lidocaine is often required to achieve control of the malignant ventricular arrhythmias in this situation. In addition to antiarrhythmic drug therapy and aggressive beta blockade, sedation and sometimes intubation are utilized to mini­mize adrenergic contribution to the VT.As an illustrative point to the contribution of sympathetic tone to the generation of recurrent VT in patients with an abnormal LVEF, bilateral sympathectomy has been shown to be effective for the suppression of acute ICD therapies for VT storm patients and has displayed durability over medium term follow up [12]. During VT storm, Stellate ganglion nerve blocks in conjunction with intravenous antiarrhythmic use can help stabilize ventricular arrhythmias.

of general anesthesia. Three dimensional mapping systems have also become standard and represent one of the most powerful tools to allow an in depth study of the ventricular chamber in question and increase the efcacy of VT ablation.

Prior to the procedure, the patient should be thoroughly assessed regarding the appropriate approach to the chamber in question. Generally the right ventricle does not pose much of a challenge outside of patients with complex congenital heart dis­ease or tricuspid valve surgery. However the left ventricle may prove inaccessible from a retroaortic or transseptal approach due to the presence of mechanical aortic or mitral valves. The location of culprit scar is also an important consideration as anterior and basal septal walls are more easily accessible from a transseptal approach while LVOT, apex, inferior, and lateral walls are via a retroaortic approach. Peripheral arterial disease can make a ret­roaortic approach difcult if not impossible which should prompt the performance of a peripheral arterial exam (bruits and pulses) prior to procedure onset. In addition, the ability to access the epi­cardial space (the absence of a prior sternotomy) should also be considered at procedure onset to determine if it is an option if required.