ECG Rhythm Analysis: Sinus Disease Part 2

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Questions and Answers

What is the definition of Sinus bradycardia?

A heart rate that is normal.

A heart rate that alternates between fast and slow.

A heart rate of more than 100 beats per minute.

A heart rate of fewer than 60 beats per minute. (correct)

What is the result of Sinoatrial block?

The heart beats too slowly.

The heart beats too quickly.

The SA node signals are blocked and cannot reach the heart's two upper chambers. (correct)

The heart beats normally.

What is Tachycardia-bradycardia syndrome?

The heart alternates between an abnormally slow and abnormally fast heart rate. (correct)

A heart rate that is always fast.

A heart rate that is normal.

A heart rate that is always slow.

What is a common cause of Sick sinus syndrome?

All of the above. Signup and view all the answers

What is the definition of Sinus arrest?

A pause of three seconds or more without any atrial activity. Signup and view all the answers

What is a symptom of Sick sinus syndrome?

The syndrome tends to be progressive. Signup and view all the answers

What is Chronotropic incompetence?

Severe, inappropriate sinus bradycardia. Signup and view all the answers

What may be associated with Sick sinus syndrome?

All of the above. Signup and view all the answers

What type of pacemaker is typically used to pace the right lower heart chamber (ventricle) of the heart?

Single chamber pacemaker Signup and view all the answers

What is the primary benefit of using a dual-chamber pacemaker in patients with sick sinus syndrome?

Reducing the incidence of atrial fibrillation Signup and view all the answers

What is chronotropic incompetence?

Failure of the heart rate to increase sufficiently with exercise or physical activity Signup and view all the answers

What is the purpose of biventricular pacing?

To stimulate both lower heart chambers Signup and view all the answers

What is a common cause of failure to reach a certain target heart rate during exercise?

Use of pharmacologic agents Signup and view all the answers

What is the recommended type of pacemaker for patients with sick sinus syndrome, except those with chronic atrial fibrillation?

Dual chamber pacemaker Signup and view all the answers

Why are artificial pacemakers well-tolerated in elderly patients?

The information is not provided in the content Signup and view all the answers

What therapy is biventricular pacing also known as?

Cardiac resynchronization therapy Signup and view all the answers

What is the most common manifestation of end-organ hypo-perfusion in patients with sick sinus syndrome?

Cerebral hypo-perfusion Signup and view all the answers

What is a common symptom experienced by patients with sick sinus syndrome?

Near-fainting spells or syncope Signup and view all the answers

What is the name of the syndrome characterized by periods of bradycardia or sinus arrest interspersed with periods of tachycardia?

Tachy-brady syndrome Signup and view all the answers

What is the condition characterized by symptoms of low cardiac output?

Chronotropic incompetence Signup and view all the answers

What is the recommended treatment for patients with symptomatic sick sinus syndrome and documented bradycardia?

Permanent pacemaker placement Signup and view all the answers

What is the most satisfactory way to correct chronotropic incompetence?

Atrial lead in a patient in complete AV block and VVI pacing Signup and view all the answers

What is the term for the abrupt stop of rapid atrial fibrillation?

Atrial fibrillation cessation Signup and view all the answers

What is the name of the syndrome characterized by symptoms of low cardiac output and chronotropic incompetence?

Sick sinus syndrome Signup and view all the answers

What is the ECG manifestation of sick sinus syndrome?

Atrial bradyarrhythmias Signup and view all the answers

What is the primary goal of pacing therapy in patients with chronotropic incompetence?

To increase cardiac output Signup and view all the answers

What is the term for the alternating periods of bradycardia and tachycardia?

Tachy-brady syndrome Signup and view all the answers

What type of pacing is associated with chronotropic incompetence?

VVI pacing Signup and view all the answers

What is the treatment for tachycardia in patients with sick sinus syndrome?

Medication to control tachycardia Signup and view all the answers

What is the name of the journal that published the study on chronotropic incompetence?

Circulation Signup and view all the answers

Study Notes

ECG Rhythm Analysis: Sick Sinus Syndrome

Sick sinus syndrome (SSS) describes dysfunction in the sinus node, leading to abnormal heart rhythms.
Characteristics of SSS include:
- Episodes of sinus bradycardia, sinus arrest, or exit block
- Combinations of sinoatrial and atrioventricular nodal conduction disturbances
- Atrial tachyarrhythmias

Types of Sick Sinus Syndrome

Sinus bradycardia: heart rate < 60 beats per minute
Sinus arrest or pause: temporary pause in SA node signals, causing skipped heartbeats
Sinoatrial block: SA node signals blocked, unable to reach the atria
Tachycardia-bradycardia (tachy-brady) syndrome: alternating between abnormally slow and fast heart rates

Causes of Sick Sinus Syndrome

Use of certain drugs (e.g. digitalis, calcium channel blockers, beta-blockers, anti-arrhythmic)
Coronary artery disease, high blood pressure, aortic and mitral valve diseases
Degenerative fibrosis of nodal tissue (most common)

Symptoms of Sick Sinus Syndrome

Often asymptomatic early in the disease course
Can present with symptoms and signs of end-organ hypoperfusion (e.g. cerebral hypo-perfusion, near-fainting spells, syncope)
End-organ hypoperfusion can also manifest as:
- Transient lightheadedness, confusion, fatigue, palpitations, angina, congestive heart failure, stroke, transient ischemic attacks, vague gastrointestinal symptoms

ECG Manifestations

Atrial bradyarrhythmias: sinus bradycardia, sinus arrest (with or without junctional escape), sinoatrial exit block, ectopic atrial bradycardia
Atrial tachyarrhythmias: atrial fibrillation, atrial flutter, atrial tachycardia, paroxysmal supraventricular tachycardia
Ventricular (escape) tachyarrhythmia
Alternating bradycardias and tachycardias: tachy-brady syndrome

Treatment

Permanent pacemaker placement recommended for patients with symptomatic SSS and documented bradycardia
Beta-blocker therapy may be used to treat tachycardia
Radiofrequency ablation may be used to cure tachycardia
Atrial-based pacemakers recommended for patients with SSS, except those with chronic atrial fibrillation

Types of Pacemakers

Single chamber pacemaker: paces the right lower heart chamber (ventricle)
Dual chamber pacemaker: paces the right lower heart chamber (ventricle) and the right upper heart chamber (atrium) separately
Biventricular pacemaker: stimulates both lower heart chambers (right and left ventricles) to improve heart function

Chronotropic Incompetence

Failure of the heart rate to increase sufficiently with exercise or physical activity due to chronotropic incompetence
Diagnosed during exercise testing when the patient is unable to reach a heart rate equivalent to at least 80% of the maximum heart rate predicted for the patient's age
Treatment: atrial lead in a patient in complete AV block and VVI pacing is the most satisfactory way to correct chronotropic incompetence in some patients

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Description

Learn about sinus disease, sick sinus syndrome, and tachycardia bradycardia syndrome. Understand the clinical significance of these abnormalities and their main types of treatment.