A patient arrives at the emergency department after experiencing multiple shocks from his ICD. The shocks were not preceded by any symptoms. He is noted to be in sinus rhythm on presentation, and, while on the monitor, he receives several more shocks from the ICD without any arrhythmias noted.
Which of the following is the most appropriate initial step in the management of this patient?
Place a “donut” magnet over the ICD site. The patient is having inappropriate or spurious shocks from the ICD, most likely caused by detection of electrical noise from a malfunction of the ICD lead. It is imperative that further shocks be prevented immediately, not only for patient comfort but also to prevent induction of life-threatening ventricular arrhythmias (including ventricular arrhythmia storm) caused by the ICD shocks. The most effective action at this point is placement of a magnet over the ICD site. This prevents the ICD from delivering any therapies. It would not be optimal to delay the prevention of further shocks while waiting for an ICD programmer. Of note, unlike pacemakers, ICDs do not have an asynchronous pacing response to application of a magnet.
Which of the following is most important for successful resuscitation of an adult patient with out-of-hospital cardiac arrest?
Early direct current (DC) shock defibrillation. The two most crucial factors that determine the value of out-of-hospital resuscitation for patients who experience sudden cardiac death are citizen-bystander cardiopulmonary resuscitation and early DC shock defibrillation.
Which of the following rhythms documented at the time of resuscitation from cardiac arrest carries the poorest prognosis for long-term survival?
Asystole. EMD or PEA and, in particular, asystole tend to be found in increasing proportions as the time since arrest increases. This is likely caused by degeneration of prolonged VF. When VF is the documented rhythm at the time of resuscitation, the long-term survival is approximately 25%. When EMD or PEA is the documented rhythm, the long-term survival rate drops to approximately 6%, and it drops even further, to approximately 1%, when asystole is documented.
Which of the following rhythm disturbances is most commonly documented for an adult with out-of-hospital sudden cardiac death resuscitated within the first 4 minutes after arrest?
VF. The initial rhythm documented in a patient who undergoes sudden cardiac death is dependent on the time elapsed since the arrest. Most episodes of sudden cardiac death (approximately 65% to 85%) that are documented electrocardiographically are caused by malignant ventricular arrhythmias such as VF. Monomorphic VT is uncommonly documented as a cause of out-of-hospital sudden cardiac death, perhaps caused by degeneration of unstable VT to VF. Asystole and EMD or PEA are found in greater proportions as the time since arrest increases, as these rhythms are likely the result of prolonged VF.
Which of the following treatment options has been most consistently shown to be effective for the primary prevention of sudden cardiac death in patients with CAD and recent MI?
β-Blocker medications. Several randomized trials of the use of β-blocker medications for patients after MI have shown efficacy for the prevention of sudden cardiac death (including propranolol, timolol, metoprolol, and acebutolol). Trials of amiodarone in this setting have provided mixed results. Two large randomized trials, the European Myocardial Infarct Amiodarone Trial (EMIAT) and the Canadian Amiodarone Myocardial Infarction Arrhythmia Trial (CAMIAT), examined the use of amiodarone in patients after MI and did not show a reduction in overall mortality with the use of amiodarone. The Polish Amiodarone Trial showed that amiodarone improved survival only in patients with preserved LV function after MI. The Survival with Oral D-sotalol (SWORD) trial studied the use of the D-isomer of sotalol (D-sotalol) in patients with recent MI and LV dysfunction. This study found worse survival in the group treated with D-sotalol than in the group treated with placebo. The Danish Investigations of Arrhythmias and Mortality on Dofetilide (DIAMOND) studies showed that dofetilide had a neutral effect on total mortality compared with placebo in the treatment of post-MI patients with LV dysfunction.
Click to expand