EKG - Normal values, Basics

Kirschoff's Law: Algebraic sum of all the potential differences in a closed circuit equals zero. Based on this law, I + II + III = 0.

But, Einthoven reversed the polarity of II. Instead of connecting RA - LL, he connected it LL - RA. Therefore, the formula becomes I - II + III = 0.

When this equation is solved, it becomes Einthoven's equation: II = I + III.

(To verify, take the net amplitude of QRS complexes respective leads from any EKG and do the calculations)

Relationship between Augmented unipolar limb leads (aVR, aVL, aVF) & Standard bipolar leads (I, II, III):

aVR = (I + II)/2

aVL = (I - III)/2

aVF = (II + III)/2

From Principles of clincal electrocardiography by Mervin J. Goldman. 11th ed. 1982. Lange Medical Publications.

Cath Lab: Artifacts in Pressure Traces...Underdamped waveform

Both panels below have LV pressure trace recorded in the same patient.
Upper panel has artifact (Underdamping of the trace)
This artifact is corrected in the lower panel.

What is the mechanism of this artifact (Underdamping)?
What are the methods that can be used to correct such artifact?

EKG - Quiz

5-mo old, VSD closure, Repair of primum ASD and Cleft Mitral Valve. Postop. Day 4. H/O Junctional Ectopic Tachycardia - controlled with Amiodarone for the 2 days.
What is the rhythm?
What is the differential diagnosis?
How would you differentiate between Junctional Rhythm from Sinus rhythm with First degree AV block?
(Click on the image to enlarge)


















Atrial lead is in V1.


















A-paced at 150 bpm.

EP: Quiz, Interpret this EKG recording

You are called to consult for irregular heart rate. A newborn who has recovered from severe sepsis was noted to have irregular heart rate on the day of discharge. Therefore, discharge was canceled and you were consulted. A PICC line was removed the day before. Baby is otherwise doing well. Here are the traces. There are no answers for these traces. Your differential diagnosis and discussion is what is expected.

Quiz: EP - Apparent Malfunction of Pacemaker

1 yr old boy, s/p Mitral Valve replacement, Postop. AV block. Epicardial DDD pacemaker. HR range is set at 110-180 bpm.
First panel (24-hr trend) shows pacemaker heart rate decreased to ~110 bpm between 6pm & 10pm, when the patient was febrile.
Second panel shows EKG prior to drop in HR.
Third panel shows EKG during the low HR at ~110 bpm (with fever).
Fourth panel shows EKG after return of HR to higher level (after fever).
Fifth panel shows current EKG at the time of review (next day).

1) What are the possible reasons for the pacemaker not to respond appropriately during a time of need (fever)?
2) What further information is needed regarding pacemaker settings to determine the cause of this pacemaker behavior?
3) What change, if any need to be made in the pacemaker settings?

Pacemaker Timing Cycles - PPT

Click on the link below for a slide set on this subject:
Pacemaker Timing Cycles PPT Pacemaker Implantation Pacemaker Implantation Guidelines Pacemaker Implantation Surgery: SlideWorld Medical PPT Search Engine

Wire shape for RPA and LPA

Image from Jim Lock's Cath Book 1987
(Diagnostic and Interventional Catheterization in Congenital Heart Disease.
James E. Lock, John F. Keane, Kenneth E. Fellows First edition 1987. Marinus Nijhoff Publishing, Boston, MA)



My first choice for LPA is just not to put any curves in the wire. But, you may need these wire shapes to enter "postop. LPAs".

Classification of Sports

36th Bethesda Conference
JACC 2005;45:1368-9

Endocarditis: Natural History of Vegetations

Click here to the posting on this topic in "Journal Club"

Troponin from skeletal muscle

Click here to the posting on this topic in "Journal Club"