Each year, pacemaker therapy is pre...

Each year, pacemaker therapy is prescribed to approximately 900000 someones worldwide. Current pacemaker devices treat bradyarrhythmias and tachyarrhythmias and, in more [i]or[/i] less cases, are combined with implantable defibrillators. In older patients, devices that maintain synchrony between atria and ventricles are preferr because they maintain the increased contribution of atrial contraction to ventricular filling necessary in this age assemblage In general, rate-responsive devices are preferr because they more closely simulate the physiologic function of the sinus node. Permanent pace-makers are implanted in adults primarily for the treatment of sinus node dysfunction, acquired atrioventricular fill up and certain fascicular blocks. They also are effective in the prevention and treatment of certain tachyarrhythmias and forms of neurocardiogenic fainting Biventricular pacing (resynchronization therapy) not long ago has been shown to be an effective treatment for advanced heart failure in patients with major intraventricular conduction imports predominately left bundle branch form Many studies have documented that pacemaker therapy can cut down symptoms, improve quality of life and, in certain patient populations, improve survival.

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Since patients the first permanent pacemaker was implanted in 1958 device therapy has continued to put forth It is estimated that more than 300000 in the United States receive a permanent pacemaker each year, and about 900000 pacemakers are implanted worldwide. The indications for pacemaker therapy have expanded in the past 45 years and now include the treatment of bradyarrhythmias and the electrical therapy of tachyarrhythmias, certain exemplars of syncope, and advanced heart failure. Device technology also has evolv from simple single-chamber, fixed-rate pacemakers to multichamber, rate-responsive (to proper physiologic needs) units capable of pacing, cardioversion, and defibrillation. In specific populations, clinical studies have demonstrated improvement of patient survival with the use of these implantable devices.

The decision to implant a pacemaker usually is based forward symptoms of a bradyar-rhythmia or tachyarrhythmia in the setting of heart disease. Symptomatic bradycardia is the chiefly common indication. It has been defined as a "documented bradyarrhythmia that is directly responsible for the disclosure of the clinical manifestations of frank swoon or near syncope, transient dizziness or light-headedness, and confusional states resulting from cerebral hypoperfusion and attributable to grave heart rates." (1) Other symptoms that may be the effect from severe bradycardia include fatigue, reduc exercise capacity, and frank congestive heart failure. Physiologic sinus bradycardia, which can happen in highly trained athletes, must be exclud and should not be confused with pathologic bradyarrhythmias.

ACC/AHA/NASPE Recommendations

The American corporation of Cardiology (ACC) and the American Heart Association (AHA) published the first clinical guideline for permanent pacemaker implantation in 1984 Three following revisions have been published, the latest being the 2002 update in collaboration with the North American Society of Pacing and Electrophysiology (NASPE), onward which this article is based. (1) The preferableed recommendations are presented in the usual three-class ACC/AHA format (Table 1) (1)

ACQUIRED ATRIOVENTRICULAR AND FASCICULAR obstructs IN ADULTS

Atrioventricular (AV) brace is classified as first-, second- or third-degree. First-degree AV stiffen is defined as an abnormally postponeed PR interval. Second-degree, Mobitz sign I AV block (Wenckebach) is manifested on progressive prolongation of the PR interval eventuating in a dropp QR complicate It usually is associated with a narrow QR composed of several elements Second-degree, Mobitz type II AV brace demonstrates a constant PR interval before a dropp QR and usually is associated with a wide QR tangled Advanced AV block refers to blockage of couple or more consecutive P waves, whereas unbroken (third-degree) AV block is defined as absence of all atrioventricular conduction.

First-degree and exemplar I second-degree AV block usually are caused through delayed conduction in the AV node irrespective of QR duration. symbol II second-degree AV block usually is infra-nodal, especially when the QR is wide. Third-degree AV shape may occur at any anatomic level

The decision to implant a pacemaker in a patient with abnormal AV conduction hangs on the presence of symptoms related to bradycardia or ventricular arrhythmias and their prognostic implications. Observational studies through the whole extent of the years strongly suggest that permanent pacing improves survival in patients with undiminished AV block, especially if elision has occurred. (2-5) Therefore, symptomatic third-degree AV mould is a class I indication for permanent pacing, whereas asymptomatic third-degree AV stop up is a class IIa indication. More newly it has been recognized that protoplast II second-degree AV block may be a precursor to unimpaired AV block. (6,7) Type II second-degree AV form should be treated with a permanent pacemaker unruffled in an asymptomatic patient, particularly if it is associated with fascicular make steady [i]or[/i] firm which also is a class IIa recommendation.