Electrocardiogram

Question 1

P wave

Answer 1

• atrial depolarization

Question 2

PR interval

Answer 2

• time for atrial depolarization and conduction from the SA node to the AV node
• normal duration is 0.12 to 0.20 seconds

Question 3

QRS complex

Answer 3

ventricular depolarization and atrial repolarization

-normal duration is 0.06 to 0.10 seconds

Question 4

QT interval

Answer 4

• time for both ventricular depolarization and repolarization
• normally ranges from 0.20 to 0.40 seconds depending on HR

Question 5

ST segment

Answer 5

• isoelectric period following QRS when the ventricles are depolarized

Question 6

Twave:

Answer 6

-ventricular repolarization

Question 7

normal sinus rhythm

Answer 7

• atrial repolarization begins in the SA node and spreads normally throughout the electrical conduction system with a HR between 60 and 100 bpm

Question 8

sinus bradycardia

Answer 8

• sinus rhythm with a heart rate less than 60 bpm

Question 9

sinus tachycardia

Answer 9

-sinus rhythm with a HR more than 100 bpm

Question 10

sinus arrhythmia

Answer 10

• sinus rhythm but with quickening and slowing of impulse formation in the SA node resulting in a slight beat-to-beat variation of the rate

Question 11

sinus arrest

Answer 11

sinus rhythm, except with intermittent failure of either SA node impulse formation or AV node conduction that results in the occcasional complete absence of P or QRS waves

Question 12

Premature atrial contractions PAC

Answer 12

• occurs when an ectopic focus in the atrium initiates an impulse before the SA node
• the P wave is premature with abnormal configuration
• PACs are very common and generally benign, but may progress to atrial flutter tachycardia or fibrillation
• may occur with a normal heart and any type of heart disease

Question 13

Atrial Flutter

Answer 13

• an ectopic very rapid atrial tachycardia
• atrial rate of 250-350 bpm; ventricular rate dependent upon AV node conduction
• saw tooth shaped P wave are characteristic
• occurs with valvular disease, ischemic heart disease, cadriomyopathy, HTN, acute myocardial infarction, chronic obstructive lung disease and pulmonary emboli
• S/S include palpitations lightheadedness and angina due to a rapid rate
• stagnation of blood may predispose to thrombi in the atria

Question 14

Atril Fibrillation

Answer 14

• common arrhythmia where the atria are depolarized between 350 and 600 times/min
• ECG shows characteristically irregular undulations of ECG baseline without discrete Pwaves
• occurs in healthy hearts and in patients with coronary arteyr disease, HTN and valvular disease
• S/S may include palpitations, fatigue, dyspnea, lightheadedness, syncope, and chest pain
• stagnation of blood may predispose to thrombi in the atria

Question 15

1dt degree Atrioventricular Block

Answer 15

• PR interval is longer than 0.2 seconds but relatively constant from beat to beat
• no symptoms or significant change in cardiac function
• PR interval may become prolonged fro many reasons including medications that supress AV conduction

Question 16

2nd degree Atrioventricular block

Answer 16

• AV conduction disturbance in which impulses between teh atria and ventricles fail intermittently
• two major types Mobitz type I and Mobitz type II block

Question 17

Mobitz I

Answer 17

• progressive prolongation of PR interval until one impulse is not conducted

Question 18

Mobitz Type II

Answer 18

• conductive PR intervals are the same and normal followed by non-conduction of one or more impulses. if heart rate is slow, CO will decr with the blocked impulse
• also 2nd degree AV block may progress to 3rd degree AV block

Question 19

3rd degree atrioventricular block

Answer 19

• all impulses are blocked at the AV node and none are transmitted to the ventricles
• the atria and ventricles are paced independently; atrial rate> ventricular rate
• Considered a medical emergency requiring a pacemaker
• if the ventricular rate is too slow, the CO drops and the patient may faint
• common causes include degenerative changes of the conduction systems, digitails, heart surgery, and acute MI

Question 20

Premature ventricular complex PVC

Answer 20

• premature depolarization arising in the ventricles due to an ectopic focus
• on ECG, the P wave is usually absent and QRS complex has a wide and aberrant shape
• common arrhythmia that occurs in healthy and diseased hearts
• Pt may be asymptomatic or have palpitations
• Common causes include anxiety, caffeine, stress, smoking and all forms of heart disease

Question 21

unifocal PVC

Answer 21

• unifocal PVCs arise from the same ectopic focus and have the same configuration

Question 22

multifocal PVC

Answer 22

• arise from different ectopic foci and have different configurations

Question 23

bigeminy

Answer 23

• normal sinus impulse is followed by a PVC

Question 24

trgeminy

Answer 24

• PVC occurs after every two normal sinus impulses

Question 25

Ventricular Tachycardia V-tach

Answer 25

• 3 or more consecutive PVCs at a ventricular rate of >150 bpm
• P wave are absent andQRS complexes are wide and aberrant in appearance
• V-tach longer than 30 sec is a life threatennig arrhythmia and requires immediate medical intervention
• Pt ar enot able to maintain an adequate BP and eventually become hypotensive
• V-tach may degenerate into venticular fibrillation causing Cardiac arrest
• common causes include: MI, cardiomyopathy and valvular disease

Question 26

Ventricular fibrillation V-fib

Answer 26

• ventricles do not beat in a coordinated fashion, but fibrillate or quiver asynchronous and ineffectively
• no cardiac output; pt becomes unconscious
• ECG shows characteristic fibrilatory waves with an irregular pattern that is either coarse or fine
• a lethal tachyarrhythmia requires immediate defibrillation
• additional measures include medications to support teh circulation and intravenous antiarrhythmic agents
• common causes include heart disease of any type, MI and cocaine use

Question 27

ventricular asystole

Answer 27

• ventricular standstill with no rhythm
• ECG records a straight-line pattern
• Requires immediate CPR and medications to stimulate cardiac activity
• common causes include acute MI, ventricular rupture, cocaine use, lightning strikes and electrical shock

Question 28

ST segment depression

Answer 28

• a depressed ST segment is a sign of subendocardial ischemia, but also can be due to digitalis toxicity or hypokalemia
• the segment is evaluated relative to isoelectric baseline at 0.08 seconds after the Jpoint
• deviations from the isoelectric baseline are expressed at ST segment depression of 1 mm. 2 mm etc

Question 29

ST segment elevation

Answer 29

• earliest sign of acute transmural infarction
• can also indicate a benign early repolarization pattern in normal heart
• deviations from the isoelectric baseline are expressed as ST segment elevation of 1 mm, 2 mm etc

Question 30

Q wave

Answer 30

• characteristic marker of infarction; signifies teh loss of positive electrical voltages due to necrosis
• significant or abnormal Qwave is longer than 0.04 msec and larger than 1/3 teh amplitude of teh R wave

Question 31

T wave inversion

Answer 31

• occurs hours or days after an MI as the result of a delay in repolarization produced by the injury
• may also occur with right and left bundle branch blocks, after a CVA, and as a normal juvenile T wave pattern in children and some adults