Ventricular arrhythmias diagnosis

Plasma steady-state levels of up to 10 /ig/ml are occasionally necessary for control of ventricular arrhythmias but cannot always be tolerated without serious toxic effects. Of thirteen patients referred to a specialist coronary care unit because of reputed refractoriness to the therapeutic effect of lignocaine, in only four was the diagnosis substantiated by demonstrating failure of therapeutic response to blood lignocaine concentrations in excess of 10 /tg/ml (H8). In four patients a therapeutic response was observed at blood lignocaine levels between 5 and 10 /xg/ml, and another five patients were responsive to lignocaine blood levels within the usual therapeutic range. 

Make a firm diagnosis. A firm arrhythmia diagnosis should be established. For example, the misuse of verapamil in patients with ventricular tachycardia mistakenly diagnosed as supraventricular tachycardia can lead to catastrophic hypotension and cardiac arrest. As increasingly sophisticated methods to characterize underlying arrhythmia mechanisms become available and are validated, it may be possible to direct certain drugs toward specific arrhythmia mechanisms. 

Bauce, B., Rampazzo, A., Basso, C., Bagattin, A., Daliento, L., Tiso, N., Turrini, P., Thiene, G., Danieli, G. A., and Nava, A. (2002). Screening for Ryanodine Receptor Type 2 Mutations in Families with Effort-Induced Polymorphic Ventricular Arrhythmias and Sudden Death Early Diagnosis of Asymptomatic Carriers. J Am Coll Cardiol 40(2) 341—9. 

Adenosine is the treatment of choice for diagnosis and reversal of supraventricular arrhythmias. Verapamil is an alternative for the management of narrow complex tachycardias. Amiodarone is the most effective drug at reversing atrial fibrillation, and in prevention of ventricular arrhythmias, but has several adverse effects. 

Bretylium tosylate is frequently used in the treatment of ventricular arrhythmias which are refractory to other anti-arrhythmic drugs. It is specifically useful in the diagnosis of ventricular tachycardia. 

To reduce mortality, administration of an aldosterone antagonist, either eplerenone or spironolactone, should be considered within the first 2 weeks following MI in all patients who are already receiving an ACE inhibitor (or ARB) and have an EF of equal to or less than 40% and either heart failure symptoms or diagnosis of diabetes mellitus.3 Aldosterone plays an important role in heart failure and in MI because it promotes vascular and myocardial fibrosis, endothelial dysfunction, hypertension, left ventricular hypertrophy, sodium retention, potassium and magnesium loss, and arrhythmias. Aldosterone antagonists have been shown in experimental and human studies to attenuate these adverse effects.70 Spironolactone decreases all-cause mortality in patients with stable, severe heart failure.71... 

ADENOSINE Adenosine (adenocard) is a nucleoside that is administered as a rapid intravenous bolus for the acute termination of reentrant supraventricular arrhythmias. Rare cases of ventricular tachycardia in patients with otherwise normal hearts are thought to be DAD-mediated and can be terminated by adenosine. Adenosine also has been used to produce controlled hypotension during some surgical procedures and in the diagnosis of coronary artery disease. 

Waldo AL, MacLean WAH. Diagnosis and treatment of cardiac arrhythmias following open heart surgery Emphasis on the use of atrial and ventricular epicardial wire electrodes. Mount Kisco, NY Futura Publishing, 1980. 

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