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Bradycardia-tachycardia syndrome; Sinus node dysfunction
Usually, no symptoms occur. Symptoms that do occur are nonspecific and may mimic other disorders.
Symptoms may include:
The patient's heart rate may be very slow at any time. Blood pressure may be normal or low.
Sick sinus syndrome may cause symptoms of heart failure to occur or worsen. Sick sinus syndrome is diagnosed when the symptoms occur only during episodes of arrhythmia. However, this often is difficult to prove.
An ECG may show various abnormal heart rhythms related to this syndrome.
Holter monitoring is an effective tool for diagnosing sick sinus syndrome because of the episodic nature of the disorder. Extremely slow heart rate and prolonged pauses may be seen during Holter monitoring, along with episodes of atrial tachycardias.
An EPS (intracardiac electrophysiology study) is a very specific test for this disorder, although it is often unable to confirm the diagnosis. It is not often needed.
Exercise testing has not proven particularly effective as a screening tool.
Olgin JE, Zipes DP. In: Specific arrhythmias: diagnosis and treatment. In: Libby P, Bonow RO, Mann DL, Zipes DP, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. St. Louis, Mo: WB Saunders; 2007:chap. 35.
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