Nonischemic regional wall motion abnormality - LBBB

Dr sajeer K TSenior Resident,

Dept. of Cardiology,Medical College, Calicut

Normal spread of electrical activity in the heart

Depolarization of the ventricular muscle starts at the left side of the interventricular septum and moves first to the right across the midportion of the septum

Normally conduction down the left bundle precedes that down the right bundle by 10 to 20 ms

Normal initial activation of the heart is in the proximal mid septum on the left ventricular side

Initial septal activation is reversed.

LBBB

Right side of the ventricular septum is initially activated

Right septal activation before activation of the body of the left ventricle

Initial right to left movement of the ventricular septum (anterior to posterior)

Interrelation between right and left ventricular events in normal subjects and LBBB

Normal M-mode Echo

Interventricular septal motion in LBBB and the relation to dynamic interventricular asynchrony.

Circulation Vol 79, No 4, April 1989

High amplitude oscillations of the IVS

Abnormal interventricular septal oscillations

LV –RV Asynchrony

- Contraction- Ejection- End systole- End diastole

M-mode echocardiogram recorded in a patient with a left bundle branch block shows an early systolic downward motion of the ventricular septum (arrows).

LBBB v/s Ejection fraction

Regional ejection fractions of apical and lateral segments similar in normal (NL) and left bundle branch block (LBBB) groups. Septal ejection fraction decreased in LBBB patients (40+16%) compared with normal subjects (67±+7%).

Circulation Vol 79, No 4, April 1989

Mechanism for global cardiac abnormalitiesin isolated left bundle branch block

Altered Ventricular Activation

Delayed LV Contraction

LV-RV Asynchrony

Abnormal septal Motion

Abnormal LV Septal EF

Decreased LV diastolic time

Nonischemic Regional Wall Motion Abnormality

Thank you