In this post we will go with the most common SVTs, VTs and Bradyarrhythmias you will encounter.
1- Supraventricular Tachyarrhythmias (SVT) includes:
- AVNRT (Atrioventricular nodal reentrant tachycardia) characterized by a P-wave which is buried in the QRS complex (usually not seen) or show up after the complex as a pseudo-R' in V1 and pseudo-S in II or buried in the ST segment as in AVRT (Atrioventricular Reciprocating Tachycardia). Treat with IV adenosine 6 then 12 mg push or IV verapamil 2.5 to 10 mg. Further management is with ablation. If contraindicated then uses AV nodes blockers like verapamil, diltiazem or beta blockers.
- Multifocal Atrial Tachycardia characterized by P-wave of at least 3 different morphologies with varying P-R intervals. Cne be seen after cardiac surgery, COPD or digoxin toxicity.
- Atrial Fibrillation characterized by absence of P-waves from all leads replaced by fibrillatory waves. The rhythm is irregularly irregular.
- Atrial Futter characterized by sawtooth P-wave pattern in inferior leads.
- Wolff-Parkinson-White (WPW) Syndrome characterized by short PR interval and Delta wave (slurred onset of the QRS) with widened QRS complex. Patients may present with tachycardia (70% AVRT and 30% Afib). This Afib might lead to Vfib and cardiac arrest.
2- Ventricular Tachyarrhythmias includes:
- Monomorphic Ventricular Tachycardia characterized by wide QRS complexes which are uniform and identical.
- Polymorphic Ventricular Tachycardia characterized by wide QRS complexes of various shapes.
- Ventricular Fibrillation characterized by chaotic irregular deflections (some call them QRS) with no distinct P waves, QRS complexes or T waves seen.
- Ventricular Flutter characterized by continuous sine wave pattern without clear QRS complexes, P waves, or T waves.
- Torsades de Pointes characterized by polymorphic ventricular tachycardia with QT interval prolongation and EKG twisting pattern.
3- Bradyarrhythmias iclude;
- Sick sinus syndrome or Sinus node dysfunction can present with various forms including Sinus Bradycardia, Sinus Arrhythmia, Sinoatrial Exit Block, Sinus Arrest — pause > 3 seconds, Atrial fibrillation with slow ventricular response and Bradycardia – tachycardia syndrome.
- First degree heart block characterized by prolonged PR interval more than 0.2 sec without effect on heart rate.
- Second degree heart block and includes Mobitz I and Mobitz II.
Mobitz 2 is characterized by blocked P-wave without PR prolongation.
- Third degree heart block is characterized by complete dissociation of P waves and QRS complexes.
Miscellaneous EKG conditions to know about:
Brugada syndrome characterized by coved ST elevation followed by a negative T-wave or biphasic positive T-wave.
Digoxin toxicity characterized by scooped ST-depression.
Hypothermia is characterized by J or Osborne waves.
Sinus rhythm with premature atrial contraction (PAC) is characterized by normal QRS complex and a normal, short, or longer PR interval than sinus rhythm. Sometimes, non-conducted PACs occur in which there is no QRS complex following the PAC. The p-wave differ from that which originate from the SAN as it is ectopic (but within the atria).
Wandering Atrial Pacemaker is characterized two Or more pacemakers competing for control over the heart’s rhythm. P Waves have different shapes. PR intervals are grossly within normal limits but are slightly variant from each other. QRS complexes are normal.
For further reading on EKGs and interpretation check this made easy book.
This post covers the points you need to know for your board exams as well as for teaching residents on the daily rounds. Medical professionals can't use the information here to treat their patients nor people can use the information her to treat themselves. If you are having any medical issues, contact your local emergency services. Please refer to your doctor for medical advice.