Cardiology Block Flashcards
What drugs are used to increase HR in an ECHO when exercise isn’t possible?
Atropine + Dobutamine
300ug or 600ug if vasovagal episode
What is the treatment following an NSTEMI?
Aspirin + Ticagrelor for 1y (Aspirin then continued for life)
ACE inhibitor
B-blocker
Statin
What is R-wave progression in ECG?
R wave gets bigger from V1-V6
What is the normal diameter of the RV and LV?
RV = 5mm LV = 15mm
What are possible causes of decreased R wave progression? Increased R wave progression?
Decreased R wave progression:
- Myocardial infarct (scar tissue)
- Dilated cardiomyopathy (larger LV to maintain SV + thinning of muscle = decreased electrical activity)
- Pericardial effusion
- Infiltrative cardiac disease
Increased R wave progression:
1. RVH (pulmonary HTN/cor pulmonale)
What is 1 small square equivalent to on ECG? 1 large square?
1 small square = 0.04s
1 large square = 0.2s
What is the definition of a broad QRS complex?
> 3 small squares (> 0.12s)
What is the normal axis on ECG?
-30º to + 90º
Note: VT can cause extreme axis deviation (not common)
What is the physiology of RBBB?
Fast depolarization through the LV and slowly depolarizes RV
What is bifasicular block?
Left axis deviation + RBBB
What do the V1/V2 leads represent? V3/V4 leads?
V1/V2 = RV leads -> big voltage here = RVH (pulmonary HTN) V3/V4 = Septal
What is atrial flutter?
Circuit in the SA node @ 300bpm and conducts @ 2:1 = 150bpm (not dependent on AV node)
- AV node slows down electrical activity
Adenosine stops AV conduction -> asystole and can be used to distinguish Atrial Flutter from SVT
Tx: DC cardio version; rate slowing drugs (same for AF)
What is SVT?
Dependent on AV node thus with adenosine SVT will be cured
What is coarse AF?
Little “rotas” forming within the atria (looks like flutter in some leads of ECG)
When are broad complex tachycardias seen?
- Ventricular origin
- SVT with BBB
- Accessory pathways (i.e. Wolff-Parkinson White syndrome)
What are the different kinds of heart block?
Type 1: Long PR
Type 2 (Mobitz 1/Wekenbach): PR gets longer and longer then dropped QRS
Type 2 (Mobitz 2): Regularly dropped QRS (2:1, 3:1 conduction)
Type 3: No relation between atria and ventricles
What are the possible characters of chest pain?
Constricting = angina, esophageal spasm, anxiety
Sharp = from pleura, pericardium, chest wall
Prolonged (>1/2h), dull, central crushing pain/pressure = MI
Where does chest pain radiate to?
To shoulder, either or both arms, neck/jaw = cardiac ischemia
Instantaneous, tearing, interscapular, retrosternal = aortic dissection
Epigastric pain may be cardiac
What are the precipitants of chest pain?
Pain associated with cold, exercise, palpitations, or emotion = cardiac pain/anxiety
Brought on by food, lying flat, hot drinks, alcohol = esophageal spasm/disease (meals can also cause angina)
What are the relieving factors of chest pain?
Relieved within minutes by rest/GTN = angina
Antacids help = GI cause
Pericardiac pain improves on leaning forward
What are associated symptoms to chest pain?
Dyspnea (with cardiac pain, PE, pleurisy, anxiety)
N/V, sweating (with MI)
Angina -> coronary artery disease + aortic stenosis, hypertrophic cardiomyopathy, paroxysmal supraventricular tachycardia -> exacerbated by anemia
Chest pain with tenderness = Tietze’s syndrome
Odd neurological symptoms + atypical chest pain = aortic dissection
What is pleuritic pain?
Pain exacerbated by inspiration. Implies inflammation of the pleura from pulmonary infection, inflammation or infarction
It causes us to “catch our breath”
Differentials:
- Musculoskeletal pain
- Fractured rib (exacerbated by gentle pressure on sternum)
- Subdiaphragmatic pathology (i.e. gallstones)
What would you do for a patient complaining of chest pain + who is acutely unwell?
- Admit
- Check pulse, BP in both arms, JVP, heart sounds
- Examine legs for DVT
- Give O2
- IV line
- Relieve pain (5-10mg IV morphine)
- Cardiac monitor
- 12-lead ECG
- CXR
- ABG
What are causes of dyspnea?
- LVF
- PE
- Any respiratory cause (i.e. pneumonia, pneumothorax)
- Anemia
- Pain
- Anxiety
What are specific symptoms associated with heart failure?
- Paroxysmal nocturnal dyspnea (waking up in the middle of the night gasping for air)
- Orthopnea (no. of pillows used to sleep)
- Peripheral oedema
What are causes of palpitations?
- Ectopics
- Sinus tachycardia
- AF
- SVT
- VT
- Thyrotoxicosis
- Anxiety
- Pheochromocytoma (rarely)
What should you ask when discussing heart palpitations?
- Previous episodes
- Precipitating/relieving factors
- Duration of symptoms
- Associated chest pain
- Dyspnea
- Dizziness
- Collapse
What questions should you ask about syncope?
- Prodromal symptoms:
- Chest pain, palpitations, dyspnea = arrhythmia
- Aura, headache, dysarthria, limb weakness = CNS cause - During the episode:
- Pulse?
- Limb jerking, tongue biting, urinary incontinence?
* Hypoxia from lack of cerebral perfusion may cause seizures - Recovery:
- Rapid = arrhythmia
- Prolonged, with drowsiness = seizure
How do you calculate the rate on an ECG if it’s regular? Irregular?
Regular = 300/(# of big squares between RR intervals)
Irregular = # of R waves x 6
Normal rate = 60-100bpm
How do you calculate rhythm on an ECG?
If cycles are not clearly equal, use the “card method”.
If not equal check if:
1. there is slight but regular lengthening + then shortening (with respiration) = sinus arrhythmia (normal in young people)
- There are different rates which are multiples of each other - varying block
- It is 100% irregular - AF or VF
What is the appearance of AF on an ECG?
AF has no discernible P waves + QRS complexes are irregularly irregular
What is the appearance of atrial flutter on ECG?
A sawtooth baseline of atrial depolarization (~300bpm) and regular QRS complexes
How would a ventricular-originating rhythm present on ECG?
QRS complexes > 0.12s (broad complex) with P waves following them or absent
What does the axis on an ECG represent?
The overall direction of depolarization across the patient’s anterior chest. This is the sum of all the ventricular electrical forces during ventricular depolarization.
What are some causes of left axis deviation?
- Left anterior hemiblock
- Inferior MI
- VT from a left ventricular focus
- Wolff-Parkinson White Syndrome
- LVH
What are some causes of right axis deviation?
- RVH
- PE
- Anterolateral MI
- Wolff-Parkinson White Syndrome
- Left posterior hemiblock
In which leads are P waves upright? Inverted?
Upright: II, III, aVF
Inverted: aVR
In which conditions is the P wave absent?
- AF
2. P hidden due to junctional or ventricular rhythm
What is P mitrale? P pulmonale?
Bifid P waves
Signifies L atrial hypertrophy
Peaked P waves
Signifies R atrial hypertrophy
Pseudo-P-pulmonale seen in hyperK+
What is the PR interval? How long is it? What does it indicate if its prolonged/shortened?
Measure from the start of the P wave to the start of the QRS complex
Normal range = 0.12-0.2s (3-5 small squares)
Prolonged = delayed AV conduction (1st degree heart block)
Shortened = Unusually fast AV conduction down an accessory pathway (i.e. WPW)
Define the components of a QRS complex
Q = First negative deflection from the isoelectric line R = Any positive deflection S = Any negative deflection after an R wave
What is the QRS complex? How long is it? What does it indicate if its prolonged/shortened?
Normal duration < 0.12s (less than 3 small squares)
Broad (> 0.12s):
- Ventricular conduction defects (bundle branch block)
- Metabolic disturbance
- Ventricular origin (i.e. ventricular ectopic)
High-amplitude QRS (normal Q waves < 0.04s wide + < 2mm deep):
- Ventricular hypertrophy
Often sen in leads I, aVL, V5-V6 and reflect normal septal depolarization
Pathological Q waves (wide + deep) = within a few hours following an acute MI
What is the QT interval?
Measure from start of QRS to end of T wave. It varies with rate.
The corrected QT interval (QTc) = QT/(RR)^0.5
Normal QTc = 0.38-0.42s
Long QT can lead to VT + sudden death
What is the ST segment?
Usually isoelectric.
Planar elevation > 1mm or depression >0.5mm implies infarction or ischemia respectively
What is the T wave?
Normally inverted in aVR, V1, occasionally V2
Normal if inverted in isolation in lead III
Abnormal if inverted in I, II, V4-V6
Peaked in hyperkalemia and flattened in hypokalemia
What is a J wave?
The J point is where the S wave finishes and ST segment starts
J wave is a notch seen at this point -> in hypothermia, SAH, hypercalcemia
What abnormalities can be seen in an ECG?
- Sinus Tachycardia: Rate > 100bpm
- Sinus bradycardia: Rate < 60bpm
- Physical fitness
- vasovagal attacks
- sick sinus syndrome
- drugs (b-blockers, digoxin, amiodarone)
- hypothyroidism
- hypothermia
- increased intracranial pressure
- cholestasis - AF
- IHD
- Thyrotoxicosis
- Hypertension
- Obesity
- Heart failure
- Alcohol - Heart Block: Disrupted passage of electrical impulse through AV node
- 1st degree HB: PR interval is prolonged + unchanging; no missed beats
- 2nd degree HB (Mobitz I): PR interval becomes longer + longer until a QRS complex is missed, the pattern then resets. This is Wenckebach phenomenon.
- 2nd degree HB (Mobitz II): QRS are regularly missed (i.e. P QRS P P QRS P - 2:1 block). This is a dangerous rhythm as it may progress to complete HB
- 3rd degree HB: No impulses passed from atria to ventricles so P waves and QRS appear independently of each other. As tissue distal to the AVN paces slowly, the patient becomes very bradycardic, and may develop hemodynamic compromise. Urgent treatment required.
- IHD (inferior MI)
- Idiopathic (fibrosis)
- Congenital
- Aortic valve calcifications
- Cardiac surgery/trauma
- Digoxin toxicity
- Infiltration (abscesses, granulomas, tumours, parasites)
What conditions cause ST elevation? ST depression?
ST elevation:
- Normal variant (high take-off)
- Acute MI (STEMI)
- Prinzmetal’s angina
- Acute pericarditis (saddle-shaped - across all leads)
- L ventricular aneurysm
ST depression:
- Normal variant (upward sloping)
- Digoxin toxicity (downward sloping)
- Ischemic (horizontal): angina, NSTEMI, acute posterior MI (ST depression in V1-V3)
When do you get T inversion on an ECG?
In V1-V3:
- Normal (black patients + children)
- RBBB
- RV strain (2º to PE)
In V2-V5:
- Anterior ischemia
- Hypertrophic cardiomyopathy
- Subarachnoid hemorrhage
- Lithium
In V4-V6 + aVL:
- Lateral ischemia
- LVH
- LBBB
In II, III, avF:
- Inferior ischemia
What is the presentation of MI on ECG?
- Within hours: T wave may become peaked + ST segments begin to rise
- Within 24h: T wave inverts. ST elevation rarely persists, unless a left ventricular aneurysm develops. T wave inversion may/may not persist.
- Within a few days: Pathological Q waves begin to form. Q waves usually persist but may resolve in 10% of patients.
- The location of these changes indicates the ischemic area location
What are considered pathological Q waves?
Q waves are considered pathological if:
- > 1mm (1 small square) wide
- > 2 mm (2 small squares) deep
- > 25% of depth of QRS complex
- Seen in leads V1-3
What ECG changes occur in PE?
- Sinus tachycardia (commonest)
- RBBB
- RV strain pattern (R axis deviation, dominant R wave + T wave inversion/ST depression in V1 + V2)
Rarely S1Q3T3 pattern occurs:
- Deep S waves in I
- Pathological Q waves in III
- Inverted T waves in III
What ECG changes are seen in digoxin toxicity?
- Down-sloping ST depression
- Inverted T wave in V5-V6 (“reversed tick”)
Any arrhythmia may occur (ventricular ectopics + nodal bradycardia are common)
What ECG changes are seen in hyperkalemia?
- Tall, tented T waves
- Widened QRS
- Absent P waves
- “sine wave” appearance
What ECG changes are seen in hypokalemia?
- Small T waves
- Prominent U waves
- Peaked P waves
What ECG changes are seen in hypercalcemia?
- Short QT interval