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KEY FEATURES

ESSENTIALS OF DIAGNOSIS

  • Weakness, orthopnea, dizziness, breathlessness, presyncope, syncope, pulmonary congestion, and altered mental status

  • Atrial rhythm and rate are dyssynchronous with the ventricular rhythm and rate

  • Appropriately timed atrial contraction does not precede the paced ventricular event

GENERAL CONSIDERATIONS

  • Prevalence is 10–50% and more common in the elderly

  • Common with VVI pacing and reduced with dual-chamber pacing

  • Diagnosis established by the objective findings of ventricular-atrial conduction, cannon waves, and transient mitral regurgitation

  • Atrial contraction and resultant atrial stretch activate the baroreceptors to produce vagally mediated vasodilatation and decrease in heart rate

  • May occur in any pacing mode when atrioventricular (AV) synchrony is uncoupled

  • Incidence has a wide range depending on whether patients were switched from an AV synchronous mode to VVI mode or were studied in VVI mode

  • In VVI mode, incidence is 7–10%

  • When switched from DDD to VVI mode, symptoms are experienced by 80% of patients

CLINICAL PRESENTATION

SYMPTOMS AND SIGNS

  • Pulsations in the neck

  • Palpitations

  • Fatigue, weakness, apprehension

  • Chest pain

  • Dyspnea

  • Dizziness

  • Presyncope, syncope

PHYSICAL EXAM FINDINGS

  • Arterial blood pressure in supine and standing position with ventricular pacing and sinus rhythm (drop of 20 mm Hg suggests pacemaker syndrome)

  • Cannon a waves

  • Pulsatile liver

  • S3 gallop, pulmonary rales

DIFFERENTIAL DIAGNOSIS

  • Newer forms of pacemaker syndromes such as prolonged AV conduction (intrinsic AV node problem or drug induced) in AAI or AAIR mode

  • AV dyssynchrony caused by mode switching

DIAGNOSTIC EVALUATION

LABORATORY TESTS

  • CBC, basic metabolic panel

ELECTROCARDIOGRAPHY

  • ECG may be used to document ventriculoatrial conduction during symptoms

  • Ambulatory ECG monitoring may be useful in confirming the diagnosis

IMAGING STUDIES

  • Doppler echocardiogram may be used to document hemodynamic changes secondary to VVI pacemaker

DIAGNOSTIC PROCEDURES

  • Hemodynamic measurements with and without pacemaker rhythm (20 mm Hg drop)

  • Relief of patient’s symptoms with SR (sinus rhythm) or AV synchrony

TREATMENT

CARDIOLOGY REFERRAL

  • Patients should be evaluated by an electrophysiologist

HOSPITALIZATION CRITERIA

  • Usually can be managed as outpatient

  • If syncope or serious symptoms occur, patient should be hospitalized

MEDICATIONS

  • Trial of antiarrhythmic drugs to eliminate retrograde ventriculoatrial conduction

THERAPEUTIC PROCEDURES

  • Atrial pacing and sensing unless contraindicated

  • In VVI pacing, upgrading to DDD mode with physiologic AV pace intervals

  • Reducing the lower rate of VVI pacing to reduce the number of paced events

SURGERY

  • Rarely may need epicardial pacemaker upgrade secondary to lack of ...

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