Lecture 8: Cardiac Arrhythmias

Question 1

In the ECG shown, which of the following heart activities is represented? (Lead III)

A. Sinus Tachycardia

B. Sinus Bradycardia

C. Complete AV block

D. Incomplete 2nd degree block

Answer 1

B. Sinus Bradycardia

Question 2

Which of the following conditions may result in tachycardia?

A. Toxic conditions of the heart

B. Increased body temperature

C. Sympathetic nerve stimulation

D. All of the above

E. B and C only

Answer 2

D. All of the above

Question 3

Circus movements are the basis of heart fibrillation. Which of the following statements is NOT true?

A. Fibrillation may occur when the refractory period of the muscle is greatly shortened

B. Fibrillation may occur when the pathway around the circle is too short

C. Fibrillation may occur when the conduction velocity slows down

D. Fibrillation may occur when the heart becomes dilated

Answer 3

B. Fibrillation may occur when the pathway around the circle is too short

Question 4

Tachycardia

Answer 4

Fast Heart Rate (>100 beats per minute); Caused from increased body temp, sympathetic nerve stimulation of heart, toxic heart conditions

Question 5

Bradycardia

Answer 5

Slow heart rate (<60 bpm); caused by athletic heart, vagal stimulation, carotid sinus syndrome

Question 6

Respiratory Spillover

Answer 6

signals from medullary respiratory center “spillover” into vasomotor center during inspiratory/expiratory cycles and cause abnormal increase/decrease number of impulses transmitted through sympathetic and vagus nerves to the heart

Question 7

Sinoatrial block

Answer 7

sudden cessation of P waves; QRS wave is slowed (standstill of atria)

Question 8

Answer 8

Sinoatrial Block

Question 9

Atrioventricular block

Answer 9

Caused by ischemia, compression, inflammation of AV node/bundle or extreme stimulation of heart by vagus nerves

Question 10

Answer 10

First-degree incomplete atrioventricular block; P-R interval is greater than 0.20 seconds (normal = 0.16 seconds)

Question 11

Answer 11

Second degree incomplete A-V block; P-R interval increase 0.25-0.45 seconds; QRS-T wave may be missing resulting in DROPPED BEATS of the ventricle

Question 12

Answer 12

Complete A-V block; no relationship between the rate of P waves and QRS-T complexes; ventricular escape due to Purkinje system acting as ectopic pacemaker

Question 13

Stokes-Adams Syndrome

Answer 13

Periodic fainting spells after complete AV block due to lack of blood to the brain prior to ventricular escape

Question 14

Answer 14

Partial Intraventricular block: “electrical alternans”; alternation in amplitude of P waves, QRS complexes, or T waves

Question 15

Answer 15

Premature contraction/beat: usually result of ectopic foci (other parts of heart inappropriately take over as pacemaker) due to ischemia, calcified plaques, irritation of conduction system/nodes

Question 16

Answer 16

Paroxysmal Tachycardia: heart becomes rapid in paroxysms, begin/end suddenly; pacemaker of heart instantly shifts back to sinus node

Question 17

Answer 17

Ventricular fibrillation

Question 18

Answer 18

Atrial Fibrillation