Digitalis Withdrawal Research Articles

Propafenone for Cardiac Arrhythmias

This chapter discusses several positive inotropic drugs and drugs used in dysrhythmias. Plasma potassium concentrations normally rise during exercise. In the study discussed in the chapter, in nine patients with atrial fibrillation during exercise at 75 W in the absence of digoxin, the peak serum potassium concentration was 4.6 mmol/L; when the serum digoxin concentration was 1.1 nmol/L, it was 4.8 mmol/L, and when the serum digoxin concentration was 2.5 nmol/L, it was 5 mmol/L. This greater increase in plasma potassium concentration during exercise in patients taking digoxin might increase its dysrhythmogenic effects. The most common presentation of digitalis toxicity in therapeutic use is with gastrointestinal adverse effects, commonly anorexia, nausea, vomiting, and diarrhea. This is also the case when poisoning occurs because of traditional medicines containing cardiac glycosides. The adverse effects of antidigoxin antibody fragments are discussed in the context of the management of digitalis toxicity. The frequency of adverse events was low (7%) and included allergic responses, possible recurrence of digitalis toxicity after treatment, and some effects attributable to the withdrawal of digitalis, such as worsening of heart failure. Amrinone can cause vasodilatation and hypotension after intravenous administration. This was reported in patients who were given intravenous amrinone rapidly during cardiopulmonary bypass. In the study discussed in the chapter, amrinone reportedly further increased intracranial pressure in a 13-year-old girl with pre-existing cerebral damage.

Digitalis withdrawal in elderly nursing home patients.

Nursing home patients were studied to determine the usefulness of a maintenance dose of digoxin in elderly patients with normal sinus rhythm. Of 64 patients, 26 were identified to be on digoxin. Thorough history and physical examination were done on all the patients. Baseline electrocardiogram showed normal sinus rhythm in 19 patients, who were observed very closely for the period of four months after withdrawal of digoxin. Eighteen of 19 patients did well without digoxin, which suggests that most of the elderly nursing home patients with normal sinus rhythm do not need a maintenance dose of digoxin.

An analysis of physicians' reasons for prescribing long-term digitalis therapy in outpatients

We examined by medical-record review why long-term digitalis therapy was prescribed in 150 outpatients, the reasons were: supraventricular tachyarrhythmias (35): supraventricular tachyarrhythmias and heart failure (33); and heart failure with sinus rhythm (82). In the patients without supraventricular tachyarrhythmias we scrutinized the diagnosis of heart failure using a clinicoradiographic scoring system and found the diagnosis unlikely in 32 patients. When these 32 patients are combined with the 31 patients who had only one occurrence of supraventricular tachyarrhythmias or heart failure, 42% of the patients were on long-term digitalis therapy for a questionable reason. We conclude that a substantial fraction of general medical outpatients might benefit from digitalis withdrawal, if evidence for heart failure is lacking or if the reason prompting digitalis therapy is isolated to the distant past.

Is digoxin really important in treatment of compensated heart failure?: A placebo-controlled crossover study in patients with sinus rhythm

To assess the efficacy of digitalis in patients with chronic clinically compensated congestive heart failure and normal sinus rhythm, we performed a double-blind crossover study with digoxin and placebo in 30 consecutive outpatients fullfilling these criteria; serum digoxin levels, clinical symptoms and signs, and objective indexes of cardiac function were monitored. No patient's clinical condition deteriorated during three months of placebo administration. Discontinuation of digoxin resulted in a small increase in echocardiographically determined resting left ventricular end-diastolic dimension (1.8 ± 0.6 mm, p < 0.001) and a similar decrease in velocity of circumferential fiber shortening (−0.08 ± 0.04 circ/sec, p < 0.05) from the corresponding values of 55.8 ± 2.3 mm and 0.90 ± 0.08 circ/sec during digitalis therapy. Resting left ventricular ejection time and preejection period were prolonged by digoxin withdrawal. Maximal exercise capacity was unchanged. No clinical exacerbation of heart failure attributable to digitalis withdrawal occurred over a follow-up period averaging 19 months. The results indicate that long-term digoxin therapy has only a minor effect on cardiac performance that is without apparent clinical importance in a representative population of ambulatory patients treated with cardiac glycosides.

Supraventricular Tachycardia: Mechanisms and Management

The phrase paroxysmal supraventricular tachycardia describes a group of arrhythmias with similar electrocardiographic features but different mechanisms that have been clarified in recent years with specialized intracardiac recording and pacing techniques. Reentry accounts for most cases and has been localized to the A-V node and less frequently to the sinus node, the atria themselves, and A-V nodal bypass tracts (Wolff-Parkinson-White syndrome). These forms of supraventricular tachycardia are initiated by premature beats that dissociate conduction between two pathways and permit the establishment of circulating electrical activity that spreads to atrial and ventricular myocardium. Paroxysms cease when the conducting properties of the reentrant circuits are disturbed by changes in autonomic tone or the application of certain drugs, pacing, or cardioversion. Supraventricular tachycardia may also result from abnormal automaticity in atrial tissues. Such automatic atrial tachycardias are often associated with A-V block ("paroxysmal atrial tachycardia with block") and may be due to digitalis intoxication. This arrhythmia is treated by withdrawal of digitalis or administration of antiarrhythmic drugs that decrease automaticity.

Concealed sinus rhythm. A cause of misdiagnosis of digitalis intoxication.

A 47-year-old man with a long history of atrial fibrillation presented with a regular rhythm and absent P waves on the surface electrocardiogram. When this rhythm persisted after digitalis withdrawal His bundle electrocardiography demonstrated sinus rhythm. Recognition of concealed sinus rhythm prevents misdiagnosis of digitalis intoxication and inappropriate withdrawal of digitalis therapy.

Hypotension, Heart Block and Reversed Pulsus Alternans in a Patient with Hypertrophic Subaortic Stenosis following Digitalis and Diuretic Therapy

Digitalis and diuretic therapy in a patient with known hypertrophic muscular subaortic stenosis was followed by heart block, pulsus alternans and hypotension. No cause for the deterioration was discovered and the patient recovered after fluid replacement and withdrawal of digitalis. It is postulated that increased obstruction due to the inotropic effect of digitalis and due to blood volume depletion caused by the diuretic led to the patient's clinical deterioration.

Influence of exercise on arrhythmias induced by digitalis-diuretic therapy in patients with atrial fibrillation

Serial low-level treadmill exercise testing was performed by 20 ambulatory patients with atrial fibrillation to provoke and study drug-related arrhythmias. All 20 were receiving long-term digitalis therapy; 19 were also receiving potassium-losing diuretic agents, and 3 had hypokalemia. The subjects were selected on the basis of resting electrocardiograms compatible with strong digitalis effects: prominent ST-T-U changes, intermittently occurring junctional beats, controlled ventricular rates (range 40 to 70/min) or ventricular premature beats. Arrhythmias suggesting digitoxicity were induced by exercise in all 20 subjects. Those occurring most often were junctional tachycardia with or without Wenckebach exit block, frequent ventricular premature beats and bigeminy. Idioventricular rhythm was induced in two subjects and ventricular parasystole in one. After withdrawal of digitalis and diuretic agents, subsequent exercise tests demonstrated increased ventricular rates, a decrease in ST-T-U changes and in the occurrence of most arrhythmias. In 18 patients, brief runs of junctional tachycardia persisted but occurred less often. Low-level exercise testing provides a simple method for provoking latent cardiac irritability in patients with suspected digitalis and diuretic toxicity; serial exercise testing after withdrawal of the drugs can demonstrate the devolution of arrhythmias.

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.

Conversion of atrial fibrillation to atrial flutter as a manifestation of digitalis toxicity ∗

A patient in whom atrial fibrillation was converted to atrial flutter as a manifestation of digitalis toxicity is described. The withdrawal of digitalis and the intravenous administration of potassium facilitated the re-establishment of the original rhythm.

Paroxysmal Atrial Tachycardia with Atrioventricular Block

Paroxysmal atrial tachycardia with block is a cardiac arrhythmia that is usually a manifestation of digitalis toxicity in patients with serious heart disease. The arrhythmia generally ends promptly after potassium administration and withdrawal of digitalis. Since the ventricular rates may be slow and regular, the arrhythmia may be difficult to recognize clinically. Atrial rates as slow as 115 per minute may be seen in cases which are otherwise typical of the condition. In our series associated pulmonary disease was present in 54 per cent and cor pulmonale in 27 per cent of the cases.

Observations on the Daily Changes in Venous Pressure and Weight in a Case of Chronic Congestive Heart Failure

A study of the effect of salt administration and digitalis withdrawal as separate factors in the production of congestive heart failure in the same patient is presented. The results indicate two different types of congestive failure relating to these modes of precipitation. Additional information is obtained as to the temporal precedence of weight and venous pressure in congestive heart failure induced by the aforementioned methods.