239 - The Bradyarrhythmias: Disorders of the Sinoatrial Node Flashcards
where does bradycardia result from?
Bradycardia results from a failure of either impulse initiation or
impulse conduction
which system modulates the rate of phase 4 diastolic depolarization?
the autonomic nervous system
which system mainly influences on the firing of the SA node and subsidiary pacemakers?
the autonomic nervous system
what are the 2 most common causes of pathologic bradycardia?
SA node dysfunction and AV conduction block
SA node dysfunction increases in frequency between the __ and __ decades of life.
fifth and sixth
SA node dysfunction should be considered in patients with: X4
fatigue
exercise intolerance
syncope
sinus bradycardia
what is the only reliable therapy for symptomatic bradycardia in the absence of extrinsic and reversible etiologies?
permanent pace making
name 7 extrinsic etiologies of SA node dysfunction:
autonomic drugs hypothyroidism sleep apnea hypoxia hypothermia ICP
name 2 autonomic etiologies for SA node dysfunction:
carotid sinus hypersensitivity
vasovagal stimulation
name at least 5 (out of 11) drugs that may lead to extrinsic SA node dysfunction:
BB CCB digoxin adenosine antiarrhythmics clonidine lithium amitriptyline phenothiazines methadone pentamidine
name at least 5 (out of 9) drugs that may lead to intrinsic SA node dysfunction:
sick sinus syndrome coronary artery disease inflammatory senile amyloidosis congenital heart disease iatrogenic (radiation/post op) chest trauma familial myotonic dystrophy
name 5 inflammatory reasons for intrinsic SA node dysfunction:
pericarditis myocarditis rheumatic heart disease collagen vascular disease Lyme disease
__ dysfunction is often reversible and generally should be corrected before __ therapy is
considered
extrinsic
pacemaker
what are the 2 most common causes of extrinsic SA node dysfunction?
drugs
autonomic nervous system
name 4 different ECG anomalies reflecting SA node dysfunction?
sinus bradycardia
sinus arrest
exit block
alternating SVT
