ecg: conduction block

ECG OF THE WEEK

PROF.VIJAYARAGHAVAN’S UNITM 7

BHARGAVI.K

HISTORY IN BRIEF 27 YR OLD FEMALE P2L2A2 WITH C/O

BREATHLESSNESS AT REST ON/OFF FOR 1 MONTH.

C/O SWELLING OF LEGS FOR 20 DAYS. COUGH WITH EXPECTORATION FOR

15 DAYS. CONDITION: PALLOR, BPPE+,B/L

CREPTS+, SM + TA.

INTERPRETATION 12 leaded ecg showing a complete heart

block-AV DISSOCIATION Atrial rate-100:ventricular rate:67-68/min RAD PR INTERVAL CANNOT BE COMMENTED QRS-BROAD N WIDE RBBB LIKE,ST DEPRESSION N T INVERSION

V1-V4.

Rhythms Produced by Conduction Block

AV Block (relatively common) 1st degree AV block Type 1 2nd degree AV block Type 2 2nd degree AV block 3rd degree AV block

SA Block (relatively rare)

Causes Ischemic heart disease, cardiomyopathy and

degenerative changes Drugs that depress AV conduction,DIGITALIS

TOXICITY Myocardial infarction, infiltration (e.g., tumor) Trauma (e.g., surgery; therapeutic ablation) Lev disease: fibro calciferous involving aortic valve

extending to conducting sys Lenegres disease: sclero degenarative process

involving conducting system CHAGAS DISEASE Congenital abnormalities

Congenital Acquired ISOLATED HEREDITARY CONNECTIVE TISSUE QRS 40-50 bpm QRS DURATION

NORMAL RATE ^WITH

ATROPINE PROXIMAL BLOCK PACE MAKER

MANDATORY

IWMI/AWMI LEVE’S LENEGRE QRS 20-30bpm PROLONGED NOT SO

DISTAL NOT SO

FIRST-DEGREE HEART BLOCK OCCURS WHEN THERE IS A PARTIAL

INTERRUPTION ANYWHERE IN THE ATRIAL OR AV JUNCTIONAL CONDUCTION SYSTEM.

THE IMPULSE IS EVENTUALLY CONDUCTED BUT IS DELAYED.

EKG Characteristics: Prolongation of the PR interval, which is constant

All P waves are conducted

MOBITZ I HEART BLOCK MOBITZ I ( WENCKEBACH OR SECOND-DEGREE

HEART BLOCK, TYPE I). PROGRESSIVE BLOCK. IMPULSE FROM THE ATRIA IS INTERRUPTED AT THE AV

JUNCTION. (1)The P-R interval becomes longer and longer

(2)The R-R interval gets shorter and shorter. THE INTERRUPTION BECOMES LONGER WITH EACH

IMPULSE DELAYING DEPOLARIZATION OF THE VENTRICLES UNTIL A COMPLETE INTERRUPTION BLOCKS THE IMPULSE.

II

Block

P P P PP

Second Degree AV Block - Type I(Wenkebach or Mobitz I Block)

MOBITZ II HEART BLOCK

OCCURS DUE TO AN INTERMITTENT INTERRUPTION NEAR OR BELOW THE AV JUNCTION.

INTERRUPTION IS NOT PROGRESSIVE, BUT OCCURS SUDDENLY

P WAVES BEFORE EVERY QRS COMPLEX AND ALL ARE THE SAME SIZE AND SHAPE.

Second Degree AV Block - Type II

P P P P P

Block

THIRD-DEGREE HEART BLOCK COMPLETE HEART BLOCK OR COMPLETE AV

DISSOCIATION. IMPULSE IS COMPLETELY BLOCKED BETWEEN THE

ATRIA AND THE VENTRICLES. USUALLY TAKES PLACE BETWEEN THE AV JUNCTION

AND BUNDLE OF HIS. 1).The atrial and the ventricular rhythms are

absolutely independent of one another .

2).There is no P-R to QRS relationship.3).The atrial rate is more rapid than the ventricular rate.4).regular P-P interval .5).rugular R-R interval

3rd Degree (Complete) AV Block

EKG Characteristics: No relationship between P waves and QRS complexes

Relatively constant PP intervals and RR intervals

Greater number of P waves than QRS complexes

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MANAGEMENT 1ST DEGREE BLOCK – ASSESS AND MONITOR THE

PATIENT. MOBITZ I ( 2ND DEGREE, TYPE I) – USUALLY DOES NOT

REQUIRE TREATMENT, BUT IF THE PATIENT IS MEDICALLY UNSTABLE OR POOR CARDIAC OUTPUT ATROPINE IS USED IF THE OVERALL RATE IS BRADYCARDIC.

MOBITZ II (2ND DEGREE, TYPE II) – OXYGEN, IV FLUIDS,ATROPINE IF OVERALL RATE IS BRADYCARDIC, ARTIFICIALPACEMAKER, DOPAMINE OR EPINEPHRINE.

IF HEART RATE IS GREATER THAN 100 BUT LESS THAN 150 DILTIAZEM, DIGOXIN, OR BETA BLOCKERS. 3RD DEGREE BLOCK – OXYGEN, IV FLUIDS, ATROPINE

IFBRADYCARDIC, DOPAMINE, EPINEPHRINE, OR ARTIFICIALPACEMAKER.