Antidysrhythmics I

Question 1

Explain enhanced automaticity and name conditions that may cause it.

Answer 1

Automaticity is the ability of cardiac muscles to depolarized spontaneously.
Enhanced automaticity is accelerated generation of action potential via normal or abnormal tissue in myocardium
May be caused by drugs, disease, reduced potassium, and changes in autonomic tone
Enhanced normal=sinus tach
Enhanced abnormal includues atrial or ventricular arrhythmias

Question 2

Explain reentry

Answer 2

When a propagating impulse fails to die out after normal activation of heart and persists to reexcite the heart after refractory period has ended.
Includes most clinically important arrhythmias

Question 3

When should arrhythmias be treated?

Answer 3

They cannot be corrected by removing the precipitating cause,
hemodynamic function is compromised, and
The disturbance predisposes to more serious cardiac dysrhythmias

Question 4

What are factors underlying cardiac dysrhythmias?

Answer 4

Myocardial Ischemia
Arterial Hypoxemia
Bradycardia
Electrolyte Imbalance
Certain Drugs
Acid-Base Changes
ANS Changes

Question 5

Increased sympathetic nervous system activity ________the threshold for ventricular fibrillation ,

Answer 5

lowers

This is attenuated by b blockers and vagal stimulation

Question 6

Bradycardia can lead to ___________ dysrhythmias

Answer 6

Ventricular.
Causes a temporal dispersion of refractory period among purkinje fibers and creates an electrical gradient between adjacent cells

Question 7

Hypokalemia and hypomagnesemia predispose to __________ dysrhythmias and should be suspected in patients treated with diuretics

Answer 7

ventricular

Question 8

acidosis/alkalosis is more likely to trigger dysrhythmias

Answer 8

alkalosis