30 Questions
What is the definition of Sinus bradycardia?
A heart rate of fewer than 60 beats per minute.
What is the result of Sinoatrial block?
The SA node signals are blocked and cannot reach the heart's two upper chambers.
What is Tachycardia-bradycardia syndrome?
The heart alternates between an abnormally slow and abnormally fast heart rate.
What is a common cause of Sick sinus syndrome?
All of the above.
What is the definition of Sinus arrest?
A pause of three seconds or more without any atrial activity.
What is a symptom of Sick sinus syndrome?
The syndrome tends to be progressive.
What is Chronotropic incompetence?
Severe, inappropriate sinus bradycardia.
What may be associated with Sick sinus syndrome?
All of the above.
What type of pacemaker is typically used to pace the right lower heart chamber (ventricle) of the heart?
Single chamber pacemaker
What is the primary benefit of using a dual-chamber pacemaker in patients with sick sinus syndrome?
Reducing the incidence of atrial fibrillation
What is chronotropic incompetence?
Failure of the heart rate to increase sufficiently with exercise or physical activity
What is the purpose of biventricular pacing?
To stimulate both lower heart chambers
What is a common cause of failure to reach a certain target heart rate during exercise?
Use of pharmacologic agents
What is the recommended type of pacemaker for patients with sick sinus syndrome, except those with chronic atrial fibrillation?
Dual chamber pacemaker
Why are artificial pacemakers well-tolerated in elderly patients?
The information is not provided in the content
What therapy is biventricular pacing also known as?
Cardiac resynchronization therapy
What is the most common manifestation of end-organ hypo-perfusion in patients with sick sinus syndrome?
Cerebral hypo-perfusion
What is a common symptom experienced by patients with sick sinus syndrome?
Near-fainting spells or syncope
What is the name of the syndrome characterized by periods of bradycardia or sinus arrest interspersed with periods of tachycardia?
Tachy-brady syndrome
What is the condition characterized by symptoms of low cardiac output?
Chronotropic incompetence
What is the recommended treatment for patients with symptomatic sick sinus syndrome and documented bradycardia?
Permanent pacemaker placement
What is the most satisfactory way to correct chronotropic incompetence?
Atrial lead in a patient in complete AV block and VVI pacing
What is the term for the abrupt stop of rapid atrial fibrillation?
Atrial fibrillation cessation
What is the name of the syndrome characterized by symptoms of low cardiac output and chronotropic incompetence?
Sick sinus syndrome
What is the ECG manifestation of sick sinus syndrome?
Atrial bradyarrhythmias
What is the primary goal of pacing therapy in patients with chronotropic incompetence?
To increase cardiac output
What is the term for the alternating periods of bradycardia and tachycardia?
Tachy-brady syndrome
What type of pacing is associated with chronotropic incompetence?
VVI pacing
What is the treatment for tachycardia in patients with sick sinus syndrome?
Medication to control tachycardia
What is the name of the journal that published the study on chronotropic incompetence?
Circulation
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
Learn about sinus disease, sick sinus syndrome, and tachycardia bradycardia syndrome. Understand the clinical significance of these abnormalities and their main types of treatment.
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