Cardiology #7 (Rhythms #2) Flashcards
What does the ECG show if the patient has paroxysmal supra ventricular tachycardia?
Orthodromic (MC type): regular, narrow-complex tachycardia (no discernible P waves due to rapid rate).
-If you can’t tell if the bump is a P or a T, it must be SVT
Treatment for PSVT
- Stable (narrow complex): Vagal maneuvers. Adenosine. Second line is CCB, BB, Digoxin.
- Stable (wide complex): Amiodarone.
- Unstable: direct current cardioversion
- Definitive: radio frequency catheter ablation.
What is unique about the ECG of a patient with multifocal atrial tachycardia?
heart rate > 100 bpm and 3 or more P wave morphologies
Multifocal atrial tachycardia is most commonly associated with what condition?
severe COPD
Treatment for multifocal atrial tachycardia?
CCB (Verapamil)
What is the pathophysiology of Wolff-Parkinson-White (WPW)
Accessory pathway (bundle of Kent) outside the AV node pre-excites the ventricles, leading to a Delta wave
What are the 3 ECG components of a patient with WPW
W: Delta wave (slurred QRS upstroke)
P: PR interval that is short
W: Wide QRS complex
Treatment for WPW
Stable: Procainamide (preferred) or Amiodarone
Unstable: Cardioversion
Definitive: radio frequency catheter ablation
What should be avoided in patients with WPW?
AV nodal blocking agents (Adenosine, BB, CCB, Digoxin)
Avoid ABCD in WPW
In AV junctional dysrhythmias, what happens?
The AV node becomes the dominant pacemaker in the heart
What is seen on the ECG in a patient with AV junctional dysrhythmias?
P waves inverted (negative) if present in leads they are normally positive (I, II, avF) or are not seen. Narrow QRS complex.
What are the three types of AV junctional dysrhythmias? (has to do with heart rate)
Junctional: 40-60 bpm
Accelerated: 60-100 bpm
Tachycardia: > 100 bpm
What is a PVC?
Premature beat originating from ventricle –> wide, bizarre QRS occurring earlier than expected. The T wave is opposite direction of QRS.
Treatment for a PVC
No treatment usually needed, as it is a common finding on an ECG
What is ventricular tachycardia defined as?
3 or more consecutive PVC’s at a rate of 100 bpm or more
MC etiology of ventricular tachycardia
- Ischemic heart disease (post-MI)
- Others: Prolonged QT interval, Hypomagnesemia, hypokalemia, Digoxin toxicity
Treatment for ventricular tachycardia
- Stable sustained VT: Amiodarone, Lidocaine, Procainamide
- Unstable VT with a pulse: Cardioversion
- VT with no pulse: Defibrillation + CPR
What is the pathophysiology of Torsades de Pointes?
Prolonged repolarization and early after depolarization + triggered activity
Causes of Torsades
- Prolonged QT interval
- Hypomagnesemia, Hypokalemia, Hypocalcemia
- Female
- Macrolides, Antipsychotics, Antiemetics
What does the ECG in Torsades de Pointes show?
Polymorphic ventricular tachycardia (alterations of the QRS amplifies on ECG around the isoelectric line)
First-line treatment for Torsades de Pointes?
IV Mag Sulfate
-Discontinue all QT prolonging drugs
MC cause of V-fib
ischemic heat disease (post MI)
Symptoms of V-fib
Unresponsive, pulseless patient, syncope
ECG of V-fib shows
-Erratic pattern of electrical impulses, no p waves
Treatment for V-fib
Unsynchronized cardioversion (Defibrillation) + CPR
Which leads correspond to a RBBB?
Leads V1-V3 (M shaped QRS complex)
-Wide QRS complex
What are the criteria for a LBBB on an ECG?
- Wide QRS complex
- Absence of Q wave in I, V5, V6
- Monomorphic R wave in I, V5, V6
- ST and T wave displacement opposite to major deflection of QRS complex
What are the two indications for Adenosine?
- PSVT: slows AV node conduction time and blocks AV nodal reentry pathways
- Pharm Cardiac Stress Testing: produces vasodilation of normal coronary arteries
Adverse effects of Adenosine
- Chest discomfort, dyspnea, flushing, headache, lightheadedness
- Serious: bronchospasm, MI
When should you NOT use Adenosine?
- 2nd and 3rd degree heart blocks
- WPW
- Asthma, COPD
Amiodarone is a _________ which prolongs the action potential
-Class III antiarrythmic (K+ channel blocker)
Amiodarone is MC used for
stable, wide-complex tachycardias
Adverse effects of Amiodarone
- Hypotension MC
- Corneal deposition with > 6 month use (MC side effect)
- Thyroid disorders
- Pulmonary fibrosis
- Increased LFTs
- Blue-green discoloration of the skin
When should you NOT use Amiodarone?
- 2nd or 3rd degree heart blocks
- WPW with concurrent A-fib
What is a useful pneumonic to remember the order of the four classes of Anti-Arrhythmic Agents, and which classes are used primarily for rhythm control and which are used for rate control?
Nets play in BK for Championship (NA+ channel blockers, BB, K+Channel blockers, Ca2+ channel blockers)
- Rhythm: Class I and III
- Rate: II and IV
Name 4 Na+ Channel Blockers
- Procainamide
- Quinidine
- Lidocaine
- Flecainide
Beta Blockers such as _______, ______, and ______ are cardio-selective. They are used in conditions such as _____ and ______.
However, they have side effects such as ______, ____, and they may mask the symptoms of _____.
- Atenolol, Metorpolol, Esmolol
- Atrial flutter, Atrial fibrillation
-Bradycardia, AV blocks, hypoglycemia
