Nodal Arrhythmias Research Articles

Unusual form of digitalis-induced triple A-V nodal rhythm

An instance of digitalis-induced triple A-V nodal rhythm has been described. To my knowledge, it is the first arrhythmia reported. The necessity of early recognition of digitalis intoxication in elderly patients who develop A-V nodal arrhythmias, particularly those multifocal in origin, during digitalization has been emphasized.

Some thoughts concerning the nomenclature of A-V nodal arrhythmias.

The fundamental mechanisms responsible for the production of the P, QRS, and T complexes in A-V nodal arrhythmias are reviewed. Particular emphasis is placed on the underlying mechanisms which lead to

Digitalis-induced cardiac arrhythmias: a report of 180 cases.

Digitalis is an essential drug in the treatment of congestive heart failure and various supraventricular arrhythmias. However, digitalis may produce or aggravate congestive heart failure and almost every known cardiac arrhythmia. A recognition of digitalis-induced arrhythmias is extremely important because cardiac arrhythmias may often indicate digitalis intoxication without any other signs.One hundred and eighty patients with digitalis intoxication studied by this author were presented. The total incidence of digitalis-induced arrhythmias was 346 episodes. The overall incidence of ventricular arrhythmias was highest (104 patients) and, among these, ventricular premature contractions predominated. The basic rhythm was atrial fibrillation in 87 patients and almost all of these patients showed either nonparoxysmal A-V nodal tachycardia or A-V nodal escape rhythm. This information is extremely important since A-V nodal arrhythmia in the presence of atrial fibrillation are frequently misinterpreted as uncomplicated atrial fibrillation. Frequent occurrence of A-V dissociation with A-V nodal arrhythmias was emphasized. Nineteen patients had atrial tachycardia and A-V conduction disturbances were encountered in 64 patients.Sudden appearance of rapid or slow heart action during digitalization should make one suspect digitalis toxicity rather than need for increased digitalis. Immediate recognition of digitalis toxicity particularly digitalisinduced arrhythmias and withdrawal of digitalis are essential to minimize the relatively high mortality.

Left atrial rhythm: Diagnostic criteria and differentiation from nodal arrhythmias

Left atrial rhythm is characterized by a left-to-right spread of atrial depolarization. The most frequent electrocardiographic pattern of this rhythm consists of upright or isoelectric P waves in lead I and inverted P waves in lead V 6. Two additional patterns, formed by negative P waves in leads I and V 6, with or without “dome and dart” P waves in lead V 1, are less common. A negative P wave in lead V 6 is the most sensitive and, in the absence of atrial inversion, the most specific sign of left atrial rhythm. The occurrence in left atrial rhythm of upright or isoelectric P waves in lead I is explained by the limitations inherent in Einthoven's triangle. Since the effective axis of lead I in Burger's triangle is inclined from the horizontal, a vector directed from left to right frequently gives rise to an upright or isoelectric deflection in lead I. The frequent appearance of inverted P waves in leads II, III and aVF in left atrial rhythm necessitates the establishment of criteria for differential diagnosis from nodal arrhythmias. Vectorial analysis of P waves in the horizontal plane as derived from the precordial leads provides the key for differentiation. In nodal and coronary sinus rhythms the horizontal P vector is directed to the left and slightly posteriorly, giving rise to negative or isodiphasic P waves in lead V 1 and to upright P waves over the left precordial leads. In left atrial rhythm the horizontal P vector points to the right and usually anteriorly, resulting in upright P waves in the right precordial leads and in negative P waves over the left precordial leads, particularly V 6.