Electrocardiogram Flashcards
1
Q
P wave
A
- atrial depolarization
2
Q
PR interval
A
- time for atrial depolarization and conduction from the SA node to the AV node
- normal duration is 0.12 to 0.20 seconds
3
Q
QRS complex
A
ventricular depolarization and atrial repolarization
-normal duration is 0.06 to 0.10 seconds
4
Q
QT interval
A
- time for both ventricular depolarization and repolarization
- normally ranges from 0.20 to 0.40 seconds depending on HR
5
Q
ST segment
A
- isoelectric period following QRS when the ventricles are depolarized
6
Q
Twave:
A
-ventricular repolarization
7
Q
normal sinus rhythm
A
- atrial repolarization begins in the SA node and spreads normally throughout the electrical conduction system with a HR between 60 and 100 bpm
8
Q
sinus bradycardia
A
- sinus rhythm with a heart rate less than 60 bpm
9
Q
sinus tachycardia
A
-sinus rhythm with a HR more than 100 bpm
10
Q
sinus arrhythmia
A
- 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
11
Q
sinus arrest
A
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
12
Q
Premature atrial contractions PAC
A
- 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
13
Q
Atrial Flutter
A
- 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
14
Q
Atril Fibrillation
A
- 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
15
Q
1dt degree Atrioventricular Block
A
- 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
16
Q
2nd degree Atrioventricular block
A
- AV conduction disturbance in which impulses between teh atria and ventricles fail intermittently
- two major types Mobitz type I and Mobitz type II block
17
Q
Mobitz I
A
- progressive prolongation of PR interval until one impulse is not conducted
18
Q
Mobitz Type II
A
- 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
19
Q
3rd degree atrioventricular block
A
- 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
20
Q
Premature ventricular complex PVC
A
- 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
21
Q
unifocal PVC
A
- unifocal PVCs arise from the same ectopic focus and have the same configuration
22
Q
multifocal PVC
A
- arise from different ectopic foci and have different configurations
23
Q
bigeminy
A
- normal sinus impulse is followed by a PVC
24
Q
trgeminy
A
- PVC occurs after every two normal sinus impulses
25
Q
Ventricular Tachycardia V-tach
A
- 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
26
Q
Ventricular fibrillation V-fib
A
- 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
27
Q
ventricular asystole
A
- 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
28
Q
ST segment depression
A
- 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
29
Q
ST segment elevation
A
- 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
30
Q
Q wave
A
- 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
31
Q
T wave inversion
A
- 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
