Emergency treatment of tachyarrhythmias

Rhythm disturbances

Patients with cardiac rhythm disturbances may present in a variety of conditions. Patients may be unstable, requiring immediate interventions, or stable, allowing for a more deliberate approach. Rapid assessment of patient stability, underlying rhythm, and determination of appropriate interventions guides timely therapy. This article discusses the differential diagnosis and treatment of adult patients presenting with primary bradyarrhythmias and tachyarrhythmias, with the exception of atrial fibrillation and atrial flutter, covered elsewhere in this issue. A concise approach to diagnosis and determination of appropriate therapy is presented.

Emergency therapy of maternal and fetal arrhythmias during pregnancy

Atrial premature beats are frequently diagnosed during pregnancy (PR); supraventricular tachycardia (SVT) (atrial tachycardia, AV-nodal reentrant tachycardia, circus movement tachycardia) is less frequently diagnosed. For acute therapy, electrical cardioversion with 50–100 J is indicated in all unstable patients (pts). In stable SVT, the initial therapy includes vagal maneuvers to terminate tachycardias. For short-term management, when vagal maneuvers fail, intravenous adenosine is the first choice drug and may safely terminate the arrhythmia. Ventricular premature beats are also frequently present during PR and benign in most of the pts; however, malignant ventricular tachyarrhythmias (sustained ventricular tachycardia [VT], ventricular flutter [VFlut] or ventricular fibrillation [VF]) may occur. Electrical cardioversion is necessary in all pts who are in hemodynamically unstable situation with life-threatening ventricular tachyarrhythmias. In hemodynamically stable pts, initial therapy with ajmaline, procainamide or lidocaine is indicated. In pts with syncopal VT, VF, VFlut or aborted sudden death, an implantable cardioverter-defibrillator is indicated. In pts with symptomatic bradycardia, a pacemaker can be implanted using echocardiography at any stage of PR. The treatment of the pregnant patient with cardiac arrhythmias requires important modifications of the standard practice of arrhythmia management. The goal of therapy is to protect the patient and fetus through delivery, after which chronic or definitive therapy can be administered.

[Management of cardiac arrhythmias during pregnancy]

INTRODUCTION

Pregnancy can precipitate or exacerbate cardiac arrhythmias. Management of those arrhythmias is not very different from that in non-pregnant women.

OBJECTIVE

In this review we tried to specify factors which favour arrhythmias in pregnant women and to show their specific management.

METHODS

We carried out a search through PubMed using as keywords: pregnancy, cardiac arrhythmias, antiarrhythmics.

RESULTS

Hemodynamic perturbations, direct electrophysiological effects of hormones and underlying heart disease are potential factors that can promote arrhythmias in pregnancy. Usually, no drug therapy is needed for the management of supraventricular or ventricular premature beats but potential promoting factors should be eliminated. In paroxysmal supraventricular tachycardia, vagal maneuvers should be tried firstly. Adenosine could be used if vagal maneuvers are ineffective. In pregnant women with atrial fibrillation, the goal of treatment is the conversion to sinus rhythm or the control of ventricular rate. Ventricular arrhythmias are usually uncommon during pregnancy and often occur in the absence of structural heart disease and are responsive to drug therapy. Symptomatic bradycardia rarely complicates pregnancy and its management does not differ from that in non-pregnant women.

Prosthetic Heart Valves and Arrhythmias in Pregnancy

The majority of women with bioprosthetic valves do not require anticoagulation during pregnancy. In women with mechanical valves, a detailed discussion of the advantages and disadvantages of the three anticoagulant options (warfarin, unfractionated heparin and low molecular weight heparin) is indicated. The majority of women with arrhythmias during pregnancy have a benign increased rate of atrial or ventricular premature beats. Those women who are hemodynamically stable can be reassured and do not usually require treatment. Women with more ominous arrhythmias should be managed in collaboration with a cardiologist, usually using the same agents that would be chosen in the non-pregnant patient, including electrical cardioversion when necessary. This is the fifth and final article in a series reviewing in detail the assessment and management of specific cardiac disorders in pregnancy.

Acute therapy of maternal and fetal arrhythmias during pregnancy

Atrial premature beats are frequently diagnosed during pregnancy. Supraventricular tachycardia (atrial tachycardia, atrioventricular nodal reentrant tachycardia, circus movement tachycardia) is diagnosed less frequently. For acute therapy, electrical cardioversion with 50 to 100 J is indicated in all unstable patients. In stable supraventricular tachycardia, the initial therapy includes vagal maneuvers to terminate tachycardias. For short-term management, when vagal maneuvers fail, intravenous adenosine is the first choice drug and may safely terminate the arrhythmia. Ventricular premature beats are also frequently present during pregnancy and are benign in most patients; however, malignant ventricular tachyarrhythmias (sustained ventricular tachycardia, ventricular flutter, or ventricular fibrillation) may occur. Electrical cardioversion is necessary in all patients who are hemodynamically unstable with life-threatening ventricular tachyarrhythmias. In hemodynamically stable patients, initial therapy with ajmaline, procainamide, or lidocaine is indicated. In patients with syncopal ventricular tachycardia, ventricular fibrillation, ventricular flutter, or aborted sudden death, an implantable cardioverter-defibrillator is indicated. In patients with symptomatic bradycardia, a pacemaker can be implanted using echocardiography at any stage of pregnancy. The treatment of the pregnant patient with cardiac arrhythmias requires important modifications of the standard practice of arrhythmia management. The goal of therapy is to protect the patient and fetus through delivery, after which chronic or definitive therapy can be administered.

Antiarrhythmic drug therapy in pregnancy and lactation

Antiarrhythmic agents commonly used in clinical practice are reviewed with respect to their potential for teratogenic or other adverse fetal effects. Although most experience with antiarrhythmic drug therapy during pregnancy has accrued with digoxin, quinidine, and propranolol, other antiarrhythmic agents may also be used in the pregnant patient if indicated. The choice of antiarrhythmic drug depends on the specific arrhythmia being treated, the cardiac condition of the patient or fetus, and the known or anticipated actions of the antiarrhythmic drug being considered. The management of specific arrhythmias encountered in pregnant women are also discussed. For benign arrhythmias, a conservative approach starting first with preventive measures is appropriate. For more severe or symptomatic arrhythmias, pharmacologic therapy should be instituted using drugs with proven safety to the fetus, if possible. Electrical cardioversion of the patient may be performed with relative safety in more emergent situations.

Wolff-Parkinson-White syndrome: illustrative case and brief review

The Wolff-Parkinson-White syndrome (WPWS) is a pre-excitation syndrome manifested on the 12-lead ECG by a short PR interval (less than .12 sec), a prolonged QRS interval (greater than .10 sec), and an initial slurring of the QRS complex called a delta wave. The anatomical etiology is the presence of accessory atrioventricular conduction fibers called the Kent bundle. Patients with the WPWS may present to the emergency department with a wide spectrum of symptoms, ranging from mild palpitations, to unstable tachydysrhythmias and sudden cardiac death. WPWS should be suspected in any patient presenting with a tachydysrhythmia with a rate exceeding 200/minute. Cardioversion is indicated in the unstable patient. It is impossible to predict the effect of any particular drug without prior electrophysiologic studies in a patient with WPWS. Procainamide is the safest drug for the stable WPWS patient with a tachydysrhythmia, including wide-complex and irregular rhythms. Verapamil is a useful drug in narrow-complex, regular rhythms, although complications have been reported. Atrial fibrillation may be difficult to diagnose in a very rapid tachycardia, and the use of verapamil in WPWS with atrial fibrillation is contraindicated. Electrophysiologic studies are indicated in the WPWS patient to maximize prophylactic therapy. An illustrative case as well as pathophysiology and management of WPWS are discussed.

Common complications in critically ill patients

Patients in intensive care units (ICUs) are subject to many complications connected with the advanced therapy required for their serious illnesses. Complications of ventilatory support include problems associated with short-term and long-term intubation, barotrauma, gastrointestinal tract bleeding, and weaning errors. Cardiac tachyarrhythmias can arise from a patient's intrinsic cardiac disease, as well as from drug therapy itself. Hemodynamic monitoring is crucial to careful patient management, but it is associated with technical complications during insertion such as pneumothorax, as well as interpretive errors such as those caused by positive end-inspiratory pressure. Acute renal failure can develop as a result both of therapy with drugs such as aminoglycosides and hypotension of many etiologies, as well as the use of contrast media. Nosocomial infection, which is a dreaded complication in ICU patients, usually arises from sources in the urinary tract, bloodstream, or lung. Complications frequently can arise if the interactions of drugs commonly used in the ICU are not recognized. Further, the ICU patient is subject to nutritional complications, acid base problems, and psychological disturbances. This monograph deals with the frequency, etiology, and prevention of these common ICU complications.