ECG: Atrial Bigeminy

1. FROM PROF.DR.NOORUL AMEEN’S UNIT
INTERESTING ECG OF THE
WEEK

2. 58 year old male Mr.Kannan, who came to
hypertension OP for routine checkup
No H/o chest pain, palpitation or syncope
Known smoker for past 20 years –10
cigarettes per day
Not an acoholic
Not a K/C/o
DM, CAD, COPD, BA, PTB, Epilepsy, Thyr
oid disease

3. Examination
Conscious
Oriented
Afebrile
CVS -S1S2 +, No murmur
RS –NVBS + No added sounds
P/A –soft
CNS –NFND
PR –84 / min, regularly irregular
BP –140 / 90 mmHg

5. ECG shows alternate complexeswith 2
population of P waves P-P interval : 0.6 sec and 1
sec
Alternating PR interval : 0.04 sec and 0.05 sec
Normal axis
QRS duration -0.8 sec
QT interval 0.4 sec
No ST –T changes
Incomplete compensatory pause
Fixed coupling interval

6. ATRIAL BIGEMINY
DISCUSSION
Due to an ectopic from a single irritable focus in
either of the atria
CAUSES
Stress
Exercise
Sympathetic over activity
Smoking
Alcoholism
Hyperthyroidism
COPD
RHD
•Drugs
•Caffeine
•Theophylline
•Cocaine
•Digoxin
•Amphetamine
•Isoproterenol

7. INCOMPLETE COMPENSATORY
PAUSE
It is a feature of atrialectopic
Sum of the pre and post ectopic interval is less
than the sum of two consequetiveintervals
MECHANISM
Transit time required to enter sinus node and reset
it followed by the time required for ensuring sinus
discharge to traverse sino-atrialjuntionand
depolariseatria
But In VPD
No influence on SA node
No re-setting of SA node
Complete compensatory pause

8. FIXED COUPLING INTERVAL
Interval between the extra-systole and the
preceding beat tends to be the same for all
unifocal extra-systoles

9. LOCALISATION
RIGHT ATRIAL
Negative / biphasic in V1
Positive followed by negative
LEFT ATRIAL
Positive or biphasic in V1
Negative followed by positive

10. A P-wave algorithm constructed on the basis of findings from 130 atrial tachycardias
correctly localized the focus in 93%

11. In Our ECG, Atrial ectopic localises to High Crista (Left
Atrium)

13. MECHANISM OF ATRIAL BIGEMINAL
RHYTHM
Sinus rhythm with alternate atrial extrasystole
Sinus rhythm with alternate sinus extra systole
Sins rhytym with alternate AV nodal extra systole
conducted retrograde to atria
Sinus rhythm with alternate ventricular
extrasystole conducted to the atria
Sinus rhythm with 3 : 2 SA block
AV nodal rhythm with 3: 2 retrograde AV block

14. DIFFERENTIAL DIAGNOSIS
Sinus arrhythmia
3 : 2 atrial block
2 : 1 atrial flutter

15. SIGNIFICANCE
Usually benign
Can be a forerunner of atrial tachycardias and
atrial fibrillations

16. THANK YOU