Arrhythmia

Question 1

What are the physiologic causes of arrhythmia?

(most common?)

Answer 1

• ischemic heart disease (most common)
• structural abnormalities

both cause abnormal conduction to occur resulting in arrhythmia

Question 2

What is sick sinus syndrome?

Answer 2

SA node becomes damaged and AV node takes over as pacemaker

Symptoms

• bradycardia
• dizziness
• synocpe

Question 3

What is atrial fibrilation?

Answer 3

independent, sporadic depolarization of atrial myocytes

-not all depolarizations transmit to the AV node (p wave w/o following QRS) -> irregularly, irregular rhythm

Question 4

What is a complication of A-fib?

Answer 4

thrombus formation in the atria

-if in left atria -> stroke

Question 5

What is heart block?

What are the types?

Answer 5

dysfunciton of conduction in the AV node

First degree block:

-prolonged PR interval

Second degree block:

• Mobtiz type I/Wenckebach: progressive lengthening of PR interval followed by dropped beat
• Mobitz type II: constant PR interval with dropped beats on regular intervals

Third degree block:

• no conduction between atria and ventricles; AV dissociation
• P wave and QRS occur in regular, but independent intervals

Question 6

What is long QT syndrome?

Complications?

Answer 6

inherited arrhythmia

• defect in K⁺ or Na⁺ ion channels used in conduction of action potentials
• worsens with physcial activity

Complications:

• V-tach (torsade de pointes)
• V-fib
• sudden cardiac death

Question 7

What is sudden cardiac death?

Answer 7

unexpected death due to a cardiac casue either w/o or shortly after onset of cardiac symptoms

Question 8

What are casues of sudden cardiac death?

(most common?)

Answer 8

-ischemia induced arrhythmia (older pts); most common

Younger pts:

• drug abuse (cocaine, meth)
• hereditary channelopathies
• hypertrophic/dilated cardiomyopathy
• hypertrophy
• myocarditis