Bundle Branch Block and Doppler

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The slurred S wave in leads I and V6 of the 12 lead electrocardiogram is characteristic of right bundle branch block and represents delayed right ventricular depolarization.

The patient below has right bundle branch block, mitral insufficiency, aortic stenosis and tricuspid insufficiency.

Continuous wave Doppler flow shows onset of the aortic ejection flow on the S wave of the QRS. The mitral insufficiency flow begins earlier - during the isovolumic period and lasts longer than the aortic ejection. These flow patterns on the left side of the heart would also be present in patients with a normal QRS duration, and are unaffected by the the delay in right ventricular depolarization in this patient.

Doppler is also useful in demonstrating the timing of mitral and tricuspid valve closure in relation to the QRS complex. It can therefore be used to demonstrate the change in timing of right sided events in right bundle branch block.

Although tricuspid insufficiency flow starts during the isovolumic period, the actual closure Doppler signal of the tricuspid valve is delayed due to the right bundle branch block.

Using the QRS for reference it is clear in the images below that the tricuspid valve Doppler closure signal is delayed when compared to time of mitral valve closure (in the image above it).

On auscultation in right bundle branch block, the first heart sound may become audibly reduplicated (split) because of this increased time delay between mitral and tricuspid valve closure.

Aortic ejection.

Mitral insufficiency.

Tricuspid insufficiency.

Fukuda N, Oki T, Iuchi A, Tabata T, Manabe K, Sasaki M, Yamada H, Ito S.
The first heart sound in atrial septal defect with reference to atrioventricular valve motion and hemodynamics.
Jpn Heart J. 1995 Nov;36(6):763-74.

Grines CL, Bashore TM, Boudoulas H, Olson S, Shafer P, Wooley CF.
Functional abnormalities in isolated left bundle branch block. The effect of interventricular asynchrony.
Circulation. 1989 Apr;79(4):845-53.

Luisada AA.
The first heart sound in normal and pathological conditions.
Jpn Heart J. 1987 Mar;28(2):143-56.

Willis PW 4th, Craige E.
First heart sound in Ebstein's anomaly: observations on the cause of wide splitting by echophonocardiographic studies before and after operative repair.
J Am Coll Cardiol. 1983 Dec;2(6):1165-8.

Luisada AA, Portaluppi F.
Peculiarities of the first heart sound in bundle branch blocks. A new interpretation based on graphic analysis.
Jpn Heart J. 1981 Sep;22(5):729-38.

Brooks N, Leech G, Leatham A.
Complete right bundle-branch block: echophonocardiographic study of first heart sound and right ventricular contraction times.
Br Heart J. 1979 Jun;41(6):637-46.

O'Toole JD, Reddy SP, Curtiss EI, Griff FW, Shaver JA.
The contribution of tricuspid valve closure to the first heart sound. An intracardiac micromanometer study.
Circulation. 1976 May;53(5):752-8.

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