EKGs

Question 1

Answer 1

first-degree heart block

• delay in transmission of the electrical impulse from the atria to the ventricles
• prolonged P-R interval beyond 0.20 seconds but constant in duration

Question 2

Answer 2

Second-degree heart block:

Type I (Wenckebach’s)

• Not all atrial impulses reach the ventricles
• P-R interval progressively lengthens until a QRS complex is dropped, and then the cycle repeats

Question 3

Answer 3

Second-degree heart block:

Type II (Mobitz’s)

• not at all atrial impulses reach the ventricles
• no delay or prolongation of P-R interval

Question 4

Answer 4

Third-degree heart block

• none of the atrial impulses reach the ventricles
• atrium and ventricles beat independently at their own regular rates (atrial rate 60 to 100 bpm, ventricular rate 40 bpm)
• No correlation between Ps and QRSTs

Question 5

Answer 5

Sinus arrhythmia:

• Normal sinus rhythm (NSR) with varying rate depending on respiration
• Rate increases w/ inspiration; rate decreases w/ expiration

Question 6

Answer 6

Asystole (sinus arrest, flatline)

• Failure of the sinus to produce an impulse, resulting in a prolonged pause

Question 7

Answer 7

Sinus bradycardia

• less than 60 beats per minute

Question 8

Answer 8

Sinus tachycardia

• More than 100 beats a minute

Question 9

Answer 9

Premature atrial contraction (PAC))

• A focus in the atrium (other than the SA node) depolarizes prematurely
• P wave appears early and abnormally shaped, or it may be lost in the previous T wave
• Causes: stimulants–coffee, tobacco, EtOH, heart disease, CHF, meds, hypoxia, low K+ levels

Question 10

Answer 10

Paroxysmal atrial tachycardia (PAT), or paroxysmal supraventricular tachycardia (PSVT)

• a focus in the atrium (other than the SA node) depolarizes, giving rise to a series of rapid beats at a regular rate b/w 150-250 per minute
• begins and ends suddenly (paroxysmal)

Question 11

Answer 11

atrial flutter

• rapid firing of an ectopic atrial focus “sawtooth” pattern
• only some beats pass to the AV node

Question 12

Answer 12

Atrial fibrillation

• multiple atrial foci depolarizing in a chaotic manner
• a small number passes through the AV node

Question 13

Answer 13

Premature ventricular contraction (PVC)

• ectopic depolarization in any portion of the ventricular myocardium
• PVCs are of little concern in they arise from the same foci or if there are less than 5 per minute
• if they arise from more than one foci or there are greater than 5 per minute, can lead to V-fib

Question 14

Answer 14

Ventricular Tachycardia

• ectopic depolarization of ventricles usually at a rate of 150-250 per minute
• can degenerate to V-Fib

Question 15

Answer 15

Ventricular fibrillation

• rapid, irregular, disorganized ventricular rhythm
• results in lack of cardiac output, no pulse, no BP

Question 16

Answer 16

Normal Sinus Rhythm (NSR)

• rate: 60-100 bpm
• P-R wave: 0.12 - 0.2 seconds
• QRS: 0.06 - 0.1 seconds
• QT: 0.32 - 0.4 seconds

Question 17

Answer 17

Wolff-Parkinson-White (WPW)

• an electrical bridge exists between the atrium and ventricles, causing a conduction bypass of the AV node
• rapid impulse transmission occurs between atrium and ventricles, resulting in PR interval < 0.12 seconds

Question 18

Answer 18

Junctional Rhythm

• heart beat originating in the AV junctional tissue as a safety mechanism when the higher pacemaker site (SA node) is not functioning or if the impulses are not getting through
• inverted P wave
• the AV junctional tissue beats at 40-60 bpm