Basics Flashcards
Name the Anterior leads of the ECG
- V2
- V3
- V4
Name the left lateral leads of the ECG
- Lead 1
- AVL
- V5
- V6
Name the inferior leads of the ECG
- aVF
- Lead 2
- Lead 3
Name the right ventricular leads of the ECG
- aVR
- V1
what is the difference between hypertrophy and enlargement of the heart?
Hypertrophy: Increase in muscle mass usually due to pressure overload like in systemic HTN or aortic stenosis.
Enlargement: Dilatation of a particular chamber usually due to volume overload like in aortic insufficiency or mitral insufficiency.
What is the normal axis of :
- QRS complex
- P wave
- T wave?
QRS = 0 to +90 ( +90 to - 30).
P wave = 0 to 70
T wave = 50 to 60
What is the normal duration and amplitude of a P wave ?
Duration: less than 0.12 second (3 small boxes)
Amplitude: Not exceed 2.5 mm ( 2.5 small boxes)
Which leads you should look at first when assessing QRS axis ?
Leads 1 and aVF.
Which leads you should look at first when assessing atrial enlargement?
P waves at lead 2 and lead V1
How to diagnose right atrial enlargement in ECG?
1- Presence of P waves with an amplitude exceeding 2.5 mm (2.5 small boxes) in at lease one of the inferior leads : lead 2, lead 3, and aVF.
2- No change in the duration of the P wave.
3- Possible right axis deviation of the P wave.
How to diagnose left atrial enlargement in an ECG?
1- Terminal (left atrial) portion of the P wave should drop (negative) at least 1 mm (1 small box) below the isoelectric line in lead V1.
2- The terminal portion of the P wave should be at least 1 small box (0.04 sec) in width.
3. No significant axis deviation is seen becuase left atrium is normally electrically dominant.
What does the electrocardiographic picture of left atrial enlargement called? and why?
P mitrale because mitral valve disease is a common cause of the left atrial enlargement.
What does the electrocardiographic picture of right atrial enlargement called? and why?
P Pulmonale because severe lung disease is the most common cause of right atrial enlargement.
How to diagnose Right ventricular hypertrophy in ECG ?
In limb leads:
- Right axis deviation is present. With QRS axis exceeding +100.
In precordial leads:
- V1 : R wave is larger than S wave.
- V6: S wave is larger than R wave.
How to diagnose left ventricular hypertrophy in ECG ?
Precordial leads:
- R wave amplitude in V5 OR V6 + S wave amplitude in lead V1 OR V2 > 35 mm.
- R wave amplitude in V5 > 26 mm.
- R wave amplitude in V6 > 20 mm
- R wave amplitude in V6 > R wave amplitude in V5
Limb leads:
- R wave amplitude in aVL > 11 mm
- R wave amplitude in aVF > 20 mm
- R wave amplitude in lead I > 13 mm
- R wave amplitude in lead 1 + S wave amplitude in lead III > 25 mm.
- R wave amplitude in aVL + S wave amplitude in V3 > 20 mm in Female / 28 mm in males.
What is the Most common cause of right ventricular hypertrophy ?
- Pulmonary disease.
2. Congenital heart disease.
What is the most common cause of left ventricular hypertrophy?
- Systemic hypertension.
2. Valvular disease.
What are the secondary repolarization abnormalities of ventricular hypertrophy?
- Downsloping ST segment depression.
- T-wave inversion.
Right ventricular repolarization abnormalities:
Leads V1 and V2
Left ventricular repolarization abnormalities:
Leads I, aVL, V5 and V6.
What are the causes / factors causing arrhythmias ?
HIS DEBS :
Hypoxia
Iscemia and Irritability
Sympathetic Stimulation.
Drugs
Electrolyte Distrubances.
Bradycardia
Stretch : Hypertrophy / enlargement
What is the most common rhythm disturbance seen in early stages of an acute myocardial infarction?
Sinus bradycardia
What is the definition of ectopic rhythms?
Ectopic rhythms are abnormal rhythms that arise from elsewhere than the sinus node.
What is an AV dissociation?
It is a lack of correlation between the P wave and a QRS complexes.
(The atria and the ventricles depolarize and contract independently of each other).
What are the 4 questions that you should ask yourself when assessing an ECG rhythm ?
- Are normal P waves present?
- Are the QRS complexes narrow or wide?
- What is the relationship between the P wave and the QRS complexes?
- Is the rhythm regular or irregular ?
What are the 5 sustained supra-ventricular arrhythmias ?
- Paroxysmal supra-ventricular tachycardia (PSVT) / AV nodal reentrant tachycardia.
- Atrial flutter
- Atrial fibrillation.
- Multifocal atrial tachycardia (MAT).
- Paroxysmal atrial tachycardia (PAT) / ectopic atrial tachycardia.
How to treat Paroxysmal Supra- Ventricular Tachycardia?
- Carotid massage
- Adenosine ( short acting AV nodal blocking agent) ( contraindicated in bronchospastic lung disease)
- Second line: beta-blockers, Calcium channel blockers.
- Rarely, electrical cardioversion
When do you see a (Saw-toothed pattern) in ECG ?
P waves in Atrial flutter
What are the common conditions associated with atrial flutter ?
- HTN
- Obesity
- DM
- Electrolyte imbalances
- Alcohol intoxication
- Drug abuse ; Cocaine and amphetamines
- Pulmonary disease
- Thyrotoxicosis
- Cardiac conditions : congenital or acquired.
What is the key in identifying atrial fibrillation in an ECG ?
Irregularly irregular appearance of QRS complexes in the absence of discrete P waves is the key to identify atrial fibrillation.
How to make the diagnosis of Multifocal Atrial Tachycardia (MAT) in ECG ?
Irregular rhythm
+
Easily identifiable P wave occurring before each QRS complex.
+
You need to identify at least 3 different P-wave morphologies.
How to differentiate between Paroxysmal Atrial Tachycardia (PAT) and Paroxysmal Supra-ventricular Tachycardia (PSVT) ?
PAT :
- warm up or cool down period
- Carotid massage has no effect on PAT ( may slow it mildly).
PSVT:
- carotid massage will slow or terminate it.
What are the rules of malignancy in Premature Ventricular Contraction PVCs ?
“Rules that could increase the risk of triggering ventricular tachycardia, ventricular fibrillation and death”.
- Frequent PVCs
- Runs of consecutive PVCs, especially three or more in a row.
- Multiform PVCs in which the PVC vary in their site of origin and hence in their appearance.
- PVCs falling on the T wave of the previous beat (R-on-T phenomenon “
- Any PVC occurring in the setting of an acute myocardial infarction.
What is the definition of ventricular tachycardia?
A run of 3 or more consecutive premature ventricular contractions PVCs.
Which types of arrhythmias are considered Emergency?
- Ventricular tachycardia.
- Ventricular fibrillation.
- Torsade de pointes
What is Torsade de Pointes ? In an ECG ?
Meaning: Twisting of the point.
It is a unique form of ventricular tachycardia that is usually seen in patients with prolonged QT intervals.
What is Ashman Phenomenon in ECG ?
A wide, aberrantly conducted supraventricular beat occurring after a QRS complex that is preceded by a long pause.
How to diagnose a First- Degree AV block ?
Prolonged PR interval : > 0.2 seconds
What are the types of conduction blocks?
- Sinus node block
- AV block:
- First-Degree AV block.
- Second-Degree AV block:- Mobitz type 1 second degree AV block (Wenckebach block).
- Mobitz type 2 second-degree AV block.
- Third-Degree AV block (Complete heart block).
- Bundle branch block.
How to diagnose Mobitz type 1 second degree AV block (Wenckebach block) ?
It requires the progressive lengthening of each successive PR interval until one P wave fails to conduct through the AV node and is therefore not followed by a QRS complex.
How to diagnose Mobitz type 2 second degree AV block?
It requires the presence of a dropped beat without progressive lengthening of the PR interval.
How to diagnose third degree AV block?
It requires the presence of AV dissociation in which the ventricular rate is slower than the sinus or atrial rate.
What are the 3 stages that occur in an ECG during myocardial infarction?
- T-wave peaking followed by T-wave inversion.
- ST - segment elevation.
- The appearance of new Q waves.
Which ECG sign is the most reliable sign of a true myocardial infarction ?
ST- segment elevation
What are the indications of a persistent ST-segment elevation in an ECG ?
Ventricular aneurysm
Where does a normal Q wave usually seen ?
- Left lateral leads : I , aVL, V5 & V6
- Inferior leads : II, III “most common” & aVF.
What are the criteria of a signifcant Q wave (pathological Q wave) ?
- The Q wave must be greater than 0.04 seconds in duration.
- The depth of Q wave must be at least one-third the hieght of the R wave in the same QRS complex.
EXCEPT lead aVR
Name the blood supply of the heart
- Right coronary artery + it’s descending branch: runs between the right atrium and the right ventricle and then swings around to the posterioe surface of the heart. It gives a descending branch that supplies the AV node.
- Left main artery:
a- Left Anterior Descending LAD : supplies anterior wall of the heart and interventricular septum.
b- Left circumflex artery: runs between the left atrium and left ventricle and supplies the lateral wall of the left ventricle.
What are the criteria of a non-Q-wave infarctions ?
- T wave inversion
- ST segement depression.
How to distinguish between angina and Non-Q-wave myocardial infarction ?
Angina :
- ST segment depression usually return to baseline shortly after the attack has subsided.
- Cardiac enzymes not elevated.
Non-Q-wave myocardial infarction:
- ST segment remain down for at least 24 hours.
- elevated cardiac enzymes.
What are the Changes that occur on an ECG in hyperkalemia?
- Peaked T waves.
- PR prolongation and P-wave flattening.
- QRS widening.
Ultimately, the QRS complexes and T waves merge to form a sine wave, and ventricular fibrillation may develop.
What are the changes that occur in an ECG in hypokalemia?
- ST segment depression
- Flattening of the T wave with prolongation of the QT interval
- U wave appearance.
What are the ECG changes occur in calcium disorders?
In Hypocalcemia: QT interval prolongation. (Associated with the lethal arrhythmia, ventricular tachycardia: Torsade de pointes”.
In hypercalcemiq : QT interval shortening.
What are the ECG changes associated with therapeutic blood levels of Digitalis ?
- ST segment depression
- T wave flattening or inversion.
- Most prominent in leads with tall R waves.
- It’s normal and predictable.
What are the ECG changes associated with toxic blood levels of Digitalis ?
- Sinus node suppression
- Conduction blocks
- Tachyarrhythmias
- Combinations :
Paroxysmal Atrial Tachycardia (PAT) with 2nd degree AV block is the most common characteristic rhythm disturbance of digitalis intoxication.
Name the medications that prolong the QT interval.
- Anti arrhythmic agents:
- Sotalol
- Quinidine
- Procainamide
- Disopyramide
- Amiodarone
- Dofetilide
- Dronedarone - Antibiotics:
- Macrolides: erythromycin, clarithromycin, azithromycin.
- Fluoroquinolones: Levofloxacin and Ciprofloxacin. - Antifungal: Ketoconazole.
- Nonsedating antihistamine: astemizole, terfenadine.
- Psychotropic drugs
- Antipsychotic: Haloperidol, Phenothiazines
- Tricyclic antidepressants: amitriptyline.
- SSRI: citalopram and fluoxetine. - Gastrointestinal meds
- Antineoplastic agents
- Diuretics
What are the ECG features of acute pericarditis and how to differentiate it from myocardial infarction?
Acute pericarditis:
- ST segment elevation
- T wave flattening or inversion.
In acute pericarditis:
- ST segment & T wave changes are diffused, involving more leads.
- ST segment is saddle shaped.
- T wave in inversion occur only after the ST segment have returned to baseline.
- No Q waves
- PR interval is depressed sometimes.
In MI :
- ST segment and T wavs changes are localized.
- T wave inversion usually precedes normalization of ST segment
What are the ECG changes that occur in Acute pulmonary embolism?
In massive PE:
- Right ventricular hypertrophy with repolarization changes
- Right bundle branch block
- Large S wave in lead I + Deep Q wave in lead III (S1Q3 pattern).
- T wave in lead III may be inverted
- Arrhythmia: sinus tachycardia and atrial fibrillation.
Q waves in acute PE are generally limited to lead III.
In non-massive PE : normal ECG usually , may show sinus tachycardia.
What is the 11 step method for reading ECGs ?
- Standardization
- Heart rate.
- Intervals
- Axis
- Rythm:
- Are there normal P wave prsent?
- Are the QRS complexs wide or narrow?
- What is the relation between the P wave and the QRS complexes ?
- Is the rythm regular or irregular ?
- Atrioventricular (AV) block
- Bundle branch block or hemiblock
- Pre-excitation.
- Enlargement or hypertrophy.
- Coronary artery disease.
- Utter confusion.
