Advances in the acute pharmacologic management of cardiac arrhythmias

A Case of Persistent and Recurrent Ventricular Fibrillation with Successful Resuscitation and Good Neurological Outcome

A 49-year-old man suffering from chest pain collapsed on arrival at an emergency department. Ventricular fibrillation was confirmed and he survived neurologically normal after 22 defibrillation shocks. This case attests that persistent and recurrent ventricular fibrillation is still compatible with good neurological outcome. Energetic and persistent efforts should be continued in such cases. Amiodarone should be considered early in the course of refractory ventricular fibrillation.

Cardiac Dysrhythmias during Donor Care

Organ procurement coordinators must treat various cardiac dysrhythmias (arrhythmias), including rhythm disturbances that may cause or follow a cardiac arrest, in about 15% to 50% of donors. Treatment decisions should be based on the particular dysrhythmia and its effect on donor blood pressure. Medications selected should be effective but short acting. In this article, data available in publications located through a PubMed search are reviewed and specific dysrhythmias that are likely to occur during donor care are described. Treatment recommendations are based on guidelines from the American Heart Association.

Failure to Treat Torsades de Pointes

A healthy 22 year old male with no history of cardiac disease was admitted with severe community acquired pneumonia that was initially treated with moxifloxacin and azithromycin. At admission, he was found to be hypokalemic and hypomagnesemic. Two days after admission, he experienced several episodes of Torsades de Pointes (TdP). He was initially treated with isoproterenol. A temporary transvenous pacemaker was inserted and set at a rate of 100 bpm. After correction of electrolytes, withdrawal of QT-prolonging medications and ventricular pacing at the mentioned heart rate, another episode of TdP ensued.We report and discuss a case of recurrent TdP in spite of conventional acute management for this condition.

Cardiovascular pharmacogenetics

Human genetic variation in the form of single nucleotide polymorphisms as well as more complex structural variations such as insertions, deletions and copy number variants, is partially responsible for the clinical variation seen in response to pharmacotherapeutic drugs. This affects the likelihood of experiencing adverse drug reactions and also of achieving therapeutic success. In this paper, we review key studies in cardiovascular pharmacogenetics that reveal genetic variations underlying the outcomes of drug treatment in cardiovascular disease. Examples of genetic associations with drug efficacy and toxicity are described, including the roles of genetic variability in pharmacokinetics (e.g. drug metabolizing enzymes) and pharmacodynamics (e.g. drug targets). These findings have functional implications that could lead to the development of genetic tests aimed at minimizing drug toxicity and optimizing drug efficacy in cardiovascular medicine.

[Efficacy of procainamide in the treatment of refractory ventricular fibrillation: report of 4 cases and a review of the literature]

Ventricular fibrillation is the most common malignant arrhythmia, found in up to 55% of patients who go on to experience cardiac arrest. Only monophasic or biphasic defibrillation has been shown to be effective. The efficacy of antiarrhythmic drugs is much lower and depends on how much time has elapsed since the onset of symptoms. In patients with persistent ventricular fibrillation refractory to shocks, treatment options are limited. We report 4 cases in which procainamide was administered at a dosage of 17 mg/kg in 1 minute. Heart rhythm was restored and pulse rate recovered in less than 3 minutes in all cases.

Life-threatening arrhythmias in the intensive care unit

Symptomatic arrhythmias are frequently observed in the intensive care unit and often lead to significant hemodynamic compromise because of the presence of multisystem disease. In particular, prompt evaluation of patients with tachycardia is critical because treatment depends on the accurate diagnosis of the arrhythmia mechanism. The electrocardiogram remains the most important diagnostic tool for the evaluation of both wide complex and narrow complex tachycardia. For wide complex tachycardia, evaluation of the atrioventricular relationship and QRS morphology are critical, and for narrow QRS complex tachycardias, evaluation focuses on identification of the location and morphology of P waves. Bradycardia can arise from sinus node dysfunction or atrioventricular conduction block.

Arrhythmias associated with respiratory syncytial virus infection

Summary A 7-week-old infant with respiratory syncytial virus infection abruptly developed complex cardiac arrhythmias in association with a low serum magnesium level. The arrhythmias were successfully treated with a single intravenous infusion of magnesium sulfate. The child was subsequently found to have a significant atrial septal defect.