Generation of arrythmias

Question 1

What is the hallmark ECG of a sinus node tachycardia?

Answer 1

p wave ends up being a little notched and comes rapidly after the T wave.

Question 2

What defects can lead to an early after depolarization?

Answer 2

Slow heart rate
Decreased plasma K+
Drug effects

Can lead to torsades de pointes

Question 3

What defects can lead to a delayed after depolarization?

Answer 3

This is caused by excessive intracellular calcium.

seen in myocardial ischemia, adrenergic stress digitalis intoxication, heart failure, and hypercalcemia.

Question 4

Which ion is greatly increased in myocardial ischemia?

Answer 4

Ischemia leads to a decrease in ATP and Na/K ATPase functionality.

This causes a great increase in K+ excretion leading to loss of conduction.

Question 5

What is seen in a 1st, second, and third degree AV block?

Answer 5

First degree will just have prolonged PR intervals.

Second Degree will have a random missing P-R interval.

Third degree block will have complete disorganization between the P and R waves.

Question 6

In order for a re-entry current to occur, the conduction time around the circuit must be longer than the ….

Answer 6

Effective refractory period within the circuit.

Question 7

What is observed in AV nodal reentrant tachycardia on ECG?

Answer 7

Narrow QRS tachycardia

140-200 bpm with sudden onset.