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Electrocardiographic and Vectorcardiographic Sequencial Demonstration of Unknown Left Trifascicular Intraventricular Conduction Block: Right Bundle Branch Block, Left Posterior Fascicular Block and Left Septal Fascicular Block: Anterior Conduction Delay

Dr. Andrés Ricardo Pérez Riera
Brazil

 Introduction

The trifascicular intraventricular block related on literatures until now includes:

1. Right Bundle Branch Block (RBBB), Left Anterior Fascicular Block (LAFB) and First Degree AV Block (incomplete Left Posterior Fascicular Block: LPFB).

2. RBBB, LPFB and First Degree AV Block (incomplete LAFB).

3. Fascicular Left Bundle Branch Block (LAFB + LPFB) and RBBB.

Objectives

Demonstration of new form of trifascicular intraventricular block.

Material and methods

We used convencional 12 electrocardiogram derivations and Frank system vectorcardiogram.

Results

The author presents a patient with exclusive dromotropic chronic chagasic miocardiopathy, that is, with ventricular size and normal function by ecocardiography, but with important evolutives dromotropic disturb.
The first one EKG on december 1986, there was only bifascicular conduction block: RBBB + LPFB. Exactly one year later, a new EKG and vectorcardiogram showed a trifascicular conduction block, not related on any medical literature that I have noticed before: RBBB + LPFB + LSFB ( Left Septal Fascicular Block: Proeminent anterior QRS forces, by anterior displacement of QRS. Anterior conduction delay).

Discussion

Until the present moment there has not been presented in sequencial form a intraventricular trifascicular block that would include the left septal fascicle (third fascicle of left bundle), associated to LPFB and RBBB.

Conclusion

Based on this real case, we think that trifascicular block acquires a new form, which should be included in the intraventricular trifascicular block.

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Electrocardiogram

Name: D.A. S. Date: 10/12/86. Age: 33y. Sex: M. Race: Caucasian. Number: 106-01. Weight: 80Kg. Hight: 1.72mts. Biotip: N. Medication: no drugs

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Clinical Diagnosis: exclusive dromotropic chronic chagasic miocardiopathy, that is, with ventricular size and function normal.
Electrocardiographic diagnosis:
Bifascicular conduction block (RBBB + LPFB): RBBB because we have:
a) QRS duration longer than 120ms with supraventricular command;
b) V1 with R wave showing nochet on ascendent ramp; ( "M complex". Equivalent to rsR’ RBBB);
c) Intrinsecoide deflection in V1 longer than 70ms;
d) Ventricular repolarization (ST-T) oposite to biggest final deflection of QRS and with assimetric T wave;
e) Left derivations (DI, aVL, V5 and V6) with S wave large.
LPFB diagnosis we made by the criteria presented below:
1) Right deviation ÂQRS nearly + 1200 (aVR isodifasic) without vertical heart or right ventricular overload;
2) SI-Q3 pattern;
3) R wave in inferior derivation with high voltage: R wave in DIII bigger than 15mm;
4) R III > RII;
5) R wave in DII and aVF with descedent ramp nochet.

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 Electrocardiogram

Name: D.A. S. Date: 03/12/87. Age: 34 Sex: M. Race: Caucasian. Number: 106-02. Weight: 80Kg. Hight: 1.72mts. Biotip: N. Medication: no drugs

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Clinical diagnosis: exclusive dromotropic chronic chagasic miocardiopathy, that is, with ventricular size and function normal.  New echocardiogram was made but there was no modifications from the one year before.

Electrocardiografic diagnosis:
1) RBBB;
2) LPFB;

3) Left septal fascicular block (LSFB): Proeminent anterior QRS forces, anterior displacement of QRS: Anterior conduction delay another form of intraventricular block.
Conclusion: Trifascicular intraventricular block: RBBB + LPFB + LSFB
This trifascicular block is different from classical form widely related: RBBB + LAFB (Left Anterior Fascicular Block) + first degree AV block. What are the differences between this EKG and the one we made one year ago?
ÂQRS with bigger deviation to the right in the frontal plane: ÂQRS was + 1200 (isodifasic aVR), and it is + 1600 now (aVR: qR);
2) Proeminent anterior QRS forces: QRS predominantly positive V1 to V5; ( The first one EKG only V1 was predominantly positive);
3) A new embrionary q wave in V1 . See the arrow on the EKG;
4) S waves with important diminuition of profundity in V5 and V6.
Itens 2, 3, and 4 make diagnosis of LSFB.
The point 2, - Proeminent anterior QRS forces – represents the activation of 40 a 60ms vector from blocked antero-medial region, responsible for proeminent anterior QRS forces of ventricular despolarization loop.
The point 3, - embrionary q wave in V1 - represent the initial 10ms forces by predominance of vector 1IP over 1AS (subendocardial activation of Infero-Posterior and Antero-Superior regions).
The point 4, - S waves with important diminuition of profundity in V5 and V6 – we explained by the competition forces of LSFB to the left, with the end forces to the right of RBBB

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Vectorcardiogram

Name: D.A. S. Date: 04/12/87. Age: 34 Sex: M. Race: Caucasian. Number: 106-01. Weight: 80Kg. Hight: 1.72mts. Biotip: N. Medication: no drugs

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Bioengineering

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Update
Mar/09/2000 


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