EKG COPY Flashcards
Atrial fibrillation
- Rate: Variable (∼150–200 beats/min)
- Rhythm: Irregular
- PR interval: No P wave; PR interval not discernible
- QT interval: QRS normal
Note: Must be differentiated from atrial flutter: (1) absence of flutter waves and presence of fibrillatory line; (2) flutter usually associated with higher ventricular rates (>150 beats/min). Loss of atrial contraction reduces cardiac output (10–20%). Mural atrial thrombi may develop. Considered controlled if ventricular rate is <100 beats/min.
Atrial flutter
- Rate: Rapid, atrial usually regular (250–350 beats/min); ventricular usually regular (<100 beats/min)
- Rhythm: Atrial and ventricular regular
- PR interval: Flutter (F) waves are saw-toothed. PR interval cannot be measured.
- QT interval: QRS usually normal; ST segment and T waves are not identifiable.
Note: Vagal maneuvers will slow ventricular response, simplifying recognition of the F waves.
AV block (1st degree)
- Rate: 60–100 beats/min
- Rhythm: Regular
- PR interval: Prolonged (>0.20 sec) and constant
- QT interval: Normal
Note: Usually clinically insignificant; may be early harbinger of drug toxicity.
AV Block (2nd degree)
Mobitz Type I / Wenckebach
- Rate: 60–100 beats/min
- Rhythm: Atrial regular; ventricular irregular
- PR interval: P wave normal; PR interval progressively lengthens with each cycle until QRS complex is dropped (dropped beat). PR interval following dropped beat is shorter than normal.
- QT interval: QRS complex normal but dropped periodically.
Note: Commonly seen in trained athletes and with drug toxicity.
AV Block (2nd degree)
Mobitz Type II
- Rate: <100 beats/min
- Rhythm: Atrial regular; ventricular regular or irregular
- PR interval: P waves normal, but some are not followed by QRS complex.
- QT interval: Normal but may have widened QRS complex if block is at level of bundle branch. ST segment and T wave may be abnormal, depending on location of block.
Note: In contrast to Mobitz type I block, the PR and RR intervals are constant and the dropped QRS occurs without warning. The wider the QRS complex (block lower in the conduction system), the greater the amount of myocardial damage.
AV Block (3rd degree)
Complete Heart Block
- Rate: <45 beats/min
- Rhythm: Atrial regular; ventricular regular; no relationship between P wave and QRS complex
- PR interval: Variable because atria and ventricles beat independently
- QT interval: QRS morphology variable, depending on the origin of the ventricular beat in the intrinsic pacemaker system (atrioventricular junctional vs. ventricular pacemaker). ST segment and T wave normal.
Note: AV block represents complete failure of conduction from atria to ventricles (no P wave is conducted to the ventricle). The atrial rate is faster than ventricular rate. P waves have no relationship to QRS complexes (e.g., they are electrically disconnected). In contrast, with AV dissociation, the P wave is conducted through the AV node and the atrial and ventricular rate are similar. Immediate treatment with atropine or isoproterenol is required if cardiac output is reduced. Consideration should be given to insertion of a pacemaker. Seen as a complication of mitral valve replacement.
Bundle Branch Block - Left
- Rate: <100 beats/min
- Rhythm: Regular
- PR interval: Normal
- QT interval: Complete LBBB (QRS >0.12 sec); incomplete LBBB (QRS = 0.10–0.12 sec); lead V1 negative RS complex; I, aVL, V6 wide R wave without Q or S component. ST segment and T-wave direction opposite direction of the R wave.
Note: LBBB does not occur in healthy patients and usually indicates serious heart disease with a poor prognosis. In patients with LBBB, insertion of a pulmonary artery catheter may lead to complete heart block.
Bundle Branch Block - Right
- Rate: <100 beats/min
- Rhythm: Regular
- PR interval: Normal
- QT interval: Complete RBBB (QRS >0.12 sec); incomplete RBBB (QRS = 0.10–0.12 sec). Varying patterns of QRS complex; rSR (V1); RS, wide R with M pattern. ST segment and T wave opposite direction of the R wave.
Note: In the presence of RBBB, Q waves may be seen with a myocardial infarction.
Digitalis effect
- Rate: <100 beats/min
- Rhythm: Regular
- PR interval: Normal or prolonged
- QT interval: ST-segment sloping (“digitalis effect”)
Note: Digitalis toxicity can be the cause of many common arrhythmias (e.g., premature ventricular contractions, second-degree heart block). Verapamil, quinidine, and amiodarone cause an increase in serum digitalis concentration.
Hypercalcemia
- Rate: <100 beats/min
- Rhythm: Regular
- PR interval: Normal - increased
- QT interval: Decreased
Hyperkalemia
- Rate: <100 beats/min
- Rhythm: Regular
- PR interval: Normal
- QT interval: Increased
-
Other:
- T wave peaked
Hypocalcemia
- Rate: <100 beats/min
- Rhythm: Regular
- PR interval: Normal
- QT interval: Increased
Hypokalemia
- Rate: <100 beats/min
- Rhythm: Regular
- PR interval: Normal
- QT interval: Normal
-
Other:
- T wave flat
- U wave
Hypothermia
- Rate: <60 beats/min
- Rhythm: Sinus
- PR interval: Prolonged
- QT interval: Prolonged
Note: Seen at temperatures below 33°C with ST-segment elevation (J point or Osborn wave). Tremor due to shivering or Parkinson’s disease may interfere with ECG interpretation and may be confused with atrial flutter. May represent normal variant of early ventricular repolarization. (Arrow indicates J point or Osborn waves.)
Multifocal Atrial Tachycardia
- Rate: 100–200 beats/min
- Rhythm: Irregular
- PR interval: Consecutive P waves are of varying shape.
- QT interval: Normal
Note: Seen in patients with severe lung disease. Vagal maneuvers have no effect. At heart rates <100 beats/min, it may appear as wandering atrial pacemaker. May be mistaken for atrial fibrillation. Treatment is of the causative disease process.
Myocardial Infarction
- Anatomic Site: Anterior
- Leads: I, aVL, V1 thru V4
-
EKG changes:
- Q waves
- ↑ ST
- ↑ T
- Vessel affected: Left anterior descending (LAD)
Myocardial Infarction
- Anatomic Site: Anteroseptal
- Leads: V1 thru V4
-
EKG changes:
- Q waves
- ↑ ST
- ↑ T
- Vessel affected: Left anterior descending (LAD)
Myocardial Infarction
- Anatomic Site: Inferior
- Leads: II, III, aVF
-
EKG changes:
- Q waves
- ↑ ST
- ↑ T
- Vessel affected: Right coronary artery (RCA)
Myocardial Infarction
- Anatomic Site: Lateral
- Leads: I, aVL, V5 and V6
-
EKG changes:
- Q waves
- ↑ ST
- ↑ T
- Vessel affected: Left circumflex
Myocardial Infarction
- Anatomic Site: Posterior
- Leads: V1 and V2
-
EKG changes:
- ↑ R
- ↓ ST
- ↓T
- Vessel affected: Left circumflex
Myocardial Ischemia
- Rate: Variable
- Rhythm: Usually regular but may show atrial and/or ventricular arrhythmias.
- PR interval: Normal
- QT interval: ST segment depressed; J-point depression; T-wave inversion; conduction disturbances. (A) TP and PR intervals are baseline for ST-segment deviation. (B) ST-segment elevation. (C) ST-segment depression.
Note: Intraoperative ischemia usually is seen in the presence of “normal” vital signs (e.g., ±20% of preinduction values).
Paroxysmal Atrial Tachycardia
- Rate: 150–250 beats/min
- Rhythm: Regular
- PR interval: Difficult to distinguish because of tachycardia obscuring P wave. P wave may precede, be included in, or follow QRS complex.
- QT interval: Normal, but ST segment and T wave may be diffcult to distinguish.
Note: Therapy depends on degree of hemodynamic compromise. Carotid sinus massage, or other vagal maneuvers, may terminate rhythm or decrease heart rate. In contrast to management of PAT in awake patients, synchronized cardioversion, rather than pharmacologic treatment, is preferred in hemodynamically unstable anesthetized patients.
Premature Atrial Contraction
- Rate: <100 beats/min
- Rhythm: Irregular
- PR interval: P waves may be lost in preceding T waves. PR interval is variable.
- QT interval: QRS normal confguration; ST segment and T wave normal.
Note: Nonconducted PAC appearance similar to that of sinus arrest; T waves with PAC may be distorted by inclusion of P wave in the T wave.
Premature Ventricular Contraction
- Rate: Usually <100 beats/min
- Rhythm: Irregular
- PR interval: P wave and PR interval absent; retrograde conduction of P wave can be seen.
- QT interval: Wide QRS (>0.12 sec); ST segment cannot be evaluated (e.g., ischemia); T wave opposite direction of QRS with compensatory pause. Fourth and eighth beats are PVCs.
Sinus Arrest
- Rate: <60 beats/min
- Rhythm: Varies
- PR interval: Variable
- QT interval: Variable
Note: Rhythm depends on the cardiac pacemaker firing in the absence of sinoatrial stimulus (atrial pacemaker 60–75 beats/min; junctional 40–60 beats/min; ventricular 30–45 beats/min). Junctional rhythm most common. Occasional P waves may be seen (retrograde P wave).
Sinus Arrhythmia
Sinus Arrhythmia
- Rate: 60–100 beats/min
- Rhythm: Sinus
- PR interval: Normal
- QT interval: R-R interval variable
Note: Heart rate increases with inhalation and decreases with exhalation + 10–20% (respiratory). Nonrespiratory sinus arrhythmia seen in elderly with heart disease. Also seen with increased intracranial pressure.
Sinus Bradycardia
- Rate: <60 beats/min
- Rhythm: Sinus
- PR interval: Normal
- QT interval: Normal
Note: Seen in trained athletes as normal variant.
Sinus Tachycardia
Sinus Tachycardia
- Rate: 100–160 beats/min
- Rhythm: Regular
- PR interval: Normal; P wave may be diffcult to see.
- QT interval: Normal
Note: Should be differentiated from paroxysmal atrial tachycardia (PAT). With PAT, carotid massage terminates arrhythmia. Sinus tachycardia may respond to vagal maneuvers but reappears as soon as vagal stimulus is removed.
Torsades De Pointes
- Rate: 150–250 beats/min
- Rhythm: No atrial component seen; ventricular rhythm regular or irregular.
- PR interval: P wave buried in QRS complex
- QT interval: QRS complexes usually wide and with phasic variation twisting around a central axis (a few complexes point upward, then a few point downward). ST segments and T waves diffcult to discern.
Note: Type of ventricular tachycardia associated with prolonged QT interval. Seen with electrolyte disturbances (e.g., hypokalemia, hypocalcemia, and hypomagnesemia) and bradycardia. Administering standard antiarrhythmics (lidocaine, procainamide, etc.) may worsen torsades de pointes. Prevention includes treatment of the electrolyte disturbance. Treatment includes shortening of the QT interval, pharmacologically or by pacing; unstable polymorphic VT is treated with immediate defibrillation.
Ventricular Fibrillation
- Rate: Absent
- Rhythm: None
- PR interval: Absent
- QT interval: Absent
Note: “Pseudoventricular fibrillation” may be the result of a monitor malfunction (e.g., ECG lead disconnect). Always check for carotid pulse before instituting therapy.
Ventricular Tachycardia
- Rate: 100–250 beats/min
- Rhythm: No atrial component seen; ventricular rhythm irregular or regular
- PR interval: Absent; retrograde P wave may be seen in QRS complex
- QT interval: Wide, bizarre QRS complex. ST segment and T wave difficult to determine.
Note: In the presence of hemodynamic compromise, VT with a pulse is treated with immediate synchronized cardioversion, whereas VT without a pulse is treated with immediate defibrillation. If the patient is stable, with short bursts of ventricular tachycardia, pharmacologic management is preferred. Should be differentiated from supraventricular tachycardia with aberrancy (SVT-A). Compensatory pause and atrioventricular dissociation suggest a PVC. P waves and SR’ (V1) and slowing to vagal stimulus also suggest SVT-A.
Wolff-Parkinson-White Syndrome (WPW)
- Rate: <100 beats/min
- Rhythm: Regular
- PR interval: P wave normal; PR interval short (<0.12 sec)
- QT interval: Duration (>0.10 sec) with slurred QRS complex (delta wave). Type A has delta wave, RBBB, with upright QRS complex V1. Type B has delta wave and downward QRS-V1. ST segment and T wave usually normal.
Note: Digoxin should be avoided in the presence of WPW because it increases conduction through the accessory bypass tract (bundle of Kent) and decreases AV node conduction; consequently, ventricular fibrillation can occur.
