ARRHYTHMIAS Flashcards
Normal QRS
Rate = 60-100
Regularity = R-R interval is same
Wide QRS
Ventricular Tachycardia
Normal sinus Rhythm
Normal P wave before every QRS
Upright P wave in Lead II
Biphasic P wave in V1
Every P wave followed by QRS
Normal Intervals
PR interval = 0.12-0.21 s
QT interval = <0.4 s
Sinus Tachycardia (5)
> 100 bpm
Normal p wave followed by QRS
Regular R-R interval
Narrow QRS
Camel hump (P merge with T)
Sinus Tachycardia- Pathophysiology
Sympathetic activation or vagal withdrawl on SA node
Sinus Tachycardia- Causes (3)
1- Increased sympathetic tone e.g. exercise, anxiety, pain, pregnancy
2- Alcohol, caffeine, drugs e.g. B-adrenergic agonists, anticholinergic drugs
3- Systemic etiology: fever, hypotension, hypovolemia, anemia, thyrotoxicosis, CHF, MI, shock, pulmonary embolism
Sinus Tachycardia- Treatment
Treat underlying cause
Consider beta blockers if symptomatic (if beta blocker is contraindicated use CCB)
Respiratory Sinus Arrhythmia
Change in sinus rhythm during respiration
Inspiration —> Faster
Expiration —> Slower
Supraventricular Tachycardias (2)
Arising above the level of the Bundle of His
Narrow QRS
Paroxysmal Supraventricular Tachycardia- Overview (2)
1- In young patients with no structural heart disease, abrupt onset and offset
2- Seen with re-entry tachycardia
Paroxysmal Supraventricular Tachycardia- Types (2)
1- AVRT (Atrioventricular)
- Anatomical reentry; accessory pathway (extra piece of conducting tissue between atria and ventricles)
- e.g. Wolf-Parkinson-White (WPW) syndrome: short PR interval, delta wave
2- AVNRT (AV node) (more common)
- Functional reentry within AV node (fast and slow pathways in AV node)
Paroxysmal Supraventricular Tachycardia- ECG (4)
1- Regular, 250bpm (fast)
2- Narrow QRS
3- P-wave sometimes hidden in QRS (bc it’s very fast)
4- ST depression
Paroxysmal Supraventricular Tachycardia- Treatment (3)
1- Termination by acutely blocking AV nodal conduction
- 1st line —> vagal manuevers, carotid massage. If not terminated —> IV Adenosine
- 2nd line —> IV BB, Diltiazem (CCB), Verapamil (CCB)
2- Preferred to cure: ablation of accessory pathway
3- Unstable patient: emergency cardioversion
Atrial Fibrillation- Overview (3)
1- Irregularly irregular, no p-waves (only fine oscillations), narrow QRS
2- Can be fast or slow depending on AV conduction
3- Tachycardia with an irregularly irregular pulse
Atrial Fibrillation- Most feared complications (3)
V. Fib, Embolism, Stroke
Atrial Fibrillation- Symptoms (5)
Palpitations, Fatigue, Dyspnea, Syncope, may precipitate or worsen heart failure
Atrial Fibrillation- Causes (7)
Cardiac (most common):
- MI
- Mitral stenosis
- HTN
Non-cardiac:
- Thyrotoxicosis
- Pulmonary embolism
- Alcohol
- Hypokalemia
Atrial Fibrillation- Diagnostic Approach (4)
1- Suspected A.Fib —> obtain an ECG
2- Confirmed A.Fib (new diagnosis) —> echo to assess cardiac function and rule out underlying structural cardiac disease (MS)
3- If A.Fib is not confirmed on ECG but strong clinical suspicion —> Holter monitor
4- Investigate for underlying cause
Atrial Fibrillation- Treatment (5)
- If patient is hemodynamically unstable —> DC cardioversion
- If patient is stable:
1- Rate control (to decrease heart rate):
- BB, CCB
- Digoxin
2- Rhythm control:
- Electrical —> DC cardioversion
- Pharmacological:
- If structural heart disease —> amiodarone
- If no heart disease —> flecianide, or propafenone
3- Anticoagulation
- Valvular A.Fib (prosthetic or moderate-severe MS) —> anticoagulate all with warfarin or NOACs
- Non-valvular A.Fib —> decide on anticoagulation using the CHA2DS2VASc score
4- Treatment of underlying cause
CHA2DS2VASc score (8)
- CHF or LVEF <= 40% (1) score of 0 —> no prophylaxis
- Hypertension (1) score of 1 —> aspirin
- Age > 75 (2) score of 2 or more —> warfarin or NOAC
- Diabeties (1)
- Stroke/TIA/Thromboembolism (2)
- Vascular disease (1)
- Age 65-74 (1)
- Female (1)
Atrial Flutter - Overview (3)
- No p-waves; saw-toothed flutter waves
- Always some degree of AV block (2:1, 3:1, 4:1)
- 150bpm, 2:1. After vagal maneuver goes to exactly 75 bpm (characteristic)
- Often occurs with A.Fib
Atrial Flutter - Associated with (5)
- Underlying heart disease, cardiomyopathy, COPD, hyperthyroidism, hypertension
Atrial Flutter - ECG
Sawtoothed waves better seen in inferior leads (II, III, aVF)
Atrial Flutter - Treatment (4)
- If unstable (e.g. hypotension, CHF, angina) —> electrical cardioversion
- If stable:
- Rate control: BB, Dilitiazem, Verapamil, or Digoxin
- Chemical cardioversion: Sotalol, Amiodarone, Type I antiarrhythmatics, or electrical cardioversion
- Anticoagulation (guidlines same as patients with A.Fib)
- Treatment of long-term atrial flutter includes anti-arrhythmics (Amiodarone, Flecianide, Propafenone) and radiofrequency or catheter ablation
Multifocal Atrial Tachycardia- Overview (6)
- A rapid, irregular atrial rhythm arising from multiple ectopic foci within the atria
- Most commonly seen in patients with severe COPD or congestive heart failure
- Characteristically commonly seen in COPD. Other hints to COPD: right axis deviation, tall R wave in V1 and deep S wave in V6 (due to right ventricular hypertrophy - cor pulmonale)
- Usually a transitional rhythm between frequent premature atrial complexes (PACs) and atrial fibrillation (differentiate from A.Fib as both have irregular narrow complex tachycardia)
- Heart rate >100bpm (usually 100-150bpm; may be as high as 250bpm)
- Irregulary irregular rhythm with varying PP, PR, and RR intervals. No flutter waves
- At least 3 distinct p-wave morphologies in the same lead
Multifocal Atrial Tachycardia- Treatment
Resolves following treatment of the underlying disorder
Multifocal Atrial Tachycardia- Progonisis
Considered by a poor prognostic sign when developing during an acute illness (—> increased mortality due to the underlying illness)
Ventricular Tachycardia - Definition (2)
- Arising below the level of the Bundle of His.
- Wide QRS
Ventricular Tachycardia - Overview (5)
- 3 or more consecutive premature ventricular beats
- Regular, Rate > 100 (usually 140-200)
- Sustained if > 30 secs; non-sustained < 30 secs
- Wide aberrant bizzare-shaped QRS
- Capture beats and fusion beats
Ventricular Tachycardia - Symptoms (6)
- Dizziness, syncope, SOB, chest pain, palpitations, sudden death
Ventricular Tachycardia - Causes (2)
- IHD
- Cardiomyopathy (hypertrophic/dilated)
Ventricular Tachycardia - Types (2)
- Monomorphic (more common)
- Polymorphic (torsade’s)
Ventricular Tachycardia - Treatment (3)
- Hemodynamically unstable: electrical cardioversion (100J)
- If hemodynamically stable: electrical cardioversion, amiodarone, Type I agents (procainamide, quinidine)
- Correction of reversible causes (hypokalemia, ischemia, HF, hypotension)
Torsade’s de points - Definition (4)
Polymorphic ventricular tachycardia (twisting of the axis: beat to beat variation in QRS shape), usually occurs in patients with a baseline of QT prolongation due to:
- Congenital Long QT syndrome
- Drugs: class IA (quinidine), class III (sotalol), phenothiazines (TCAs), erythromycin, quinolones, antihistamines
- Electrolyte disturbances: Hypokalemia, hypomagnesemia
Torsade’s de points - Treatment
IV Magnesium sulfate. Correct the underlying cause of prolonged QT
Ventricular Fibrillation - Definition
A very rapid and irregular ventricular activation with no mechanical effect and therefore no cardiac output
Ventricular Fibrillation - Presentation
Patient pulseless and becomes rapidly unconscious, and respiration ceases (cardiac arrest)
Ventricular Fibrillation - Treatment
Immediate defibrillation
Survivors at high risk of sudden death and treatment is with an ICD
Cardioversion Vs Defibrillation (5)
Cardioversion:
- Shock in synchrony with QRS complex
- Has a pulse but hemodynamically unstable
- A.Fib, atrial flutter, SVT, VT with a pulse
- 50-200 Joules
- Elective, patient awake and frequently sedated
Defibrillation:
- Shock NOT in synchrony with QRS complex
- Patient is pulseless
- V.Fib, VT without pulse
- 200-360 Joules
- Emergency, patient is unconscious
Sinus Bradycardia - Definition
< 60 bpm. Normal p-wave followed by QRS. Regular (regular R-R interval)
Sinus Bradycardia - Causes (3)
- Normal —> during sleep, athletes
- Extrinsic to heart: BB intake, hypothyroidism, hypothermia
- Intrinsic to heart:
- Acute ischemia and infarction of the node (complication of MI)
- Degenerative changes: fibrosis of atrium and node “sick sinus syndrome”
Sinus Bradycardia - Treatment (2)
- Could be normal/stop offending agent (BB, CCB)/Atropine
- Patients with persistent symptomatic bradycardia treated with a permanent cardiac pacemaker
Sick Sinus Syndrome- Definition
Failure of sinus node to depolarize (sinus arrest) or failure of the sinus impulse to propagate to the atria (sinoatrial block) —> BRADYCARDIA —> this will cause ectopic pacemaker activity and tachyarrhythmias (tachy-brady syndrome)
Sick Sinus Syndrome- ECG
Severe sinus bradycardia or intermittent long pauses between consecutive P waves
Sick Sinus Syndrome- Treatment (2)
Permanent pacemaker insertion and anti-coagulation
AV Blocks - 1st Degree (2)
- AV conduction excessively slowed (but all conducted)
- Constant PR
AV Blocks - 2nd Degree
AV conduction occasionally blocked
- Mobitz I: PR increases progressively until beat dropped
- Mobitz II: PR is constant then beat is dropped
AV Blocks - 3rd Degree (complete heart block)
AV conduction is completely blocked
- P waves marching through
- QRSs without correlating P waves
AV Blocks - Treatment (2)
- Unstable: Atropine then percutaneous pacing
- Mobitz II and 3rd degree: Pacemaker
Bundle Branch Blocks - Left bundle branch block (4)
- Wide QRS
- Broad R with prolonged upstroke in the lateral leads (I, aVL, V5, V6)
- ST depression and T wave inversion
- Reciprocal changes in V1 and V2
Bundle Branch Blocks - Right Bundle Branch Block (4)
- Wide QRS
- RSR’ in V1 and V2 (rabbit ears)
- ST depression and T wave inversion
- Reciprocal changes in the lateral leads (I, aVL, V5, V6)
Anti-arrhythmics (4)
NO BODY KNOWS CARDIOLOGY
1- No —> Na channel blockers
- Increased AP —> quinidine procainamide
- Decreased AP —> lidocaine
- Same AP —> Flecianide
2- Body —> Beta blockers
- MOA: decreased HR, decreased force of contraction, decreased BP
- e.g. Propanolol, atenolol, bisoprolol
- side effects: bradycardia, increased intermittent claudication, decreased glucose tolerance
3- Knows —> K channel blockers
- e.g. Amiodarone, sotalol
- side effects: hypo/hyperthyroidism, skin, liver toxicity, corneal micro-deposits
4- Cardiology —> Ca channel blockers
- Non dihydro: verapamil, dilitazem
Anti-arrhythmics - General rules
If hemodynamically stable:
- Bradycardia: Atropine
- Supraventricular tachycardia: ABCD (adenosine, BB, CCB, digoxin)
- Ventricular tachycardia: LAPS (Lidocaine, Amiodarone, Procainamide, Sotalol)
If hemodynamically unstable:
- Bradycardia: Pacemaker
- Tachycardia: DC shock
