"What is Bundle Block syndrome mean and how serious is it?"

Let's start with a lesson in anatomy and physiology of the heart.  During a normal heartbeat, there is an electrical impulse that is initiated in the SA node in top part of the heart (the atrium) and travels down to the AV node.  From there it continues to the Bundle of His, which separates into a right and left bundle branch, until it reaches the Purkinje fibers.  Think of the electricity like a car traveling on the highway from Ohio to Florida, where it needs to stop at several gas stations before it arrives at its destination.  When there is a delay in the conduction of the electrical activity, it is called a "block."  Kind of like the car sputtering.  A bundle branch block means there is a delay in the conduction of electrical activity in the bundle branches. 

What does all this mean?  It depends on the situation, because it can be caused by several different things: coronary artery disease, cardiomyopathy, heart attack, heart failure, mitral valve prolapse, myocarditis...the list goes on and on.  Obviously, the extent of "how serious" a bundle branch block is  depends on the reason it is happening. 

Many people continue their normal daily activities in life never even knowing they have a block; others may need hospitalization, medication(s), or even a pacemaker. 

I guess what I'm trying to say is that a block in itself doesn't mean much; it needs to be correlated clinically by what your symptoms are and your other health issues.   

Hope this wasn't too confusing.  Best wishes to you. 

I hope this information is of some help to you.  You must talk this over with your doctor as he can give you more specific information than what information I found.

...because believe me, this is so complicated but a wonderful information.

OK. our heart, specifically the sinoatrial node, creates electric impulse to be transmitted to valves and myocardium (muscle of the heart) making it contract and letting blood flow. this is called electrical conduction system of the heart. this is the physiological explanation why our heart beats.

there is one area which is the Bundle of His, which transmits the impulse from the sinoatrial node to the right and left area of the heart.

if you have a bundle block syndrome, or better called bundle branch syndrome, the impulse that is transmitted will not be send appropriately causing either altered pathway or nothing at all. this may cause the heart beat very slow or not synchronized making the blood flow minimal ang not sufficient.

it really depends what kind of bundle block you have because there are a lot of different degrees for bundle block. there are some cases that people with bundle block are still active. in any case, you might need a pacemaker to normalize the impulse and beat of your heart. 

"The heart's electrical activity normally starts in the sinoatrial node (the heart's natural pacemaker), which is situated on the upper right atrium. From there the impulse travels to the left atrium and the atrioventricular node. From the AV node the electrical impulse travels down the Bundle of His and divides into the right and left bundle branches. The right bundle branch contains one fascicle. The left bundle branch subdivides into two fascicles: the left anterior fascicle and the left posterior fascicle. Ultimately, the fascicles divide into millions of Purkinje fibers which in turn interdigitize with individual cardiac myocytes, allowing for rapid, coordinated, and synchronous depolarization of the ventricles.

 Bundle branch blocks

When a bundle branch or fascicle becomes injured (due to underlying heart disease, myocardial infarction, or cardiac surgery), it may cease to conduct electrical impulses appropriately. This results in altered pathways for ventricular depolarization. Since the electrical impulse can no longer use the preferred pathway across the bundle branch, it may move instead through muscle fibers in a way that both slows the electrical movement and changes the direction of the impulses. As a result, there is a loss of ventricular synchrony, ventricular depolarization is prolonged, and there may be a corresponding drop in cardiac output. When heart failure is present, a pacemaker may be used to resynchronize the ventricles.

Diagnosis and treatment

A bundle branch block can be diagnosed when the duration of the QRS complex on the ECG exceeds 120 ms. A right bundle branch block typically causes prolongation of the last part of the QRS complex, and may shift the heart's electrical axis slightly to the right. The ECG will show a terminal R wave in lead V1 and a slurred S wave in lead I. Left bundle branch block widens the entire QRS, and in most cases shifts the heart's electrical axis to the left. The ECG will show a QS or rS complex in lead V1 and a monophasic R wave in lead I. Another normal finding with bundle branch block is appropriate T wave discordance. In other words, the T wave will be deflected opposite the terminal deflection of the QRS complex.

Many people with bundle branch blocks may still be quite active, and may have nothing more remarkable than an abnormal appearance to their ECG. However, when bundle blocks are complex and diffuse in the bundle systems, or associated with additional and significant ventricular muscle damage, they may be a sign of serious underlying heart disease. In more severe cases, a pacemaker may be required to re-establish better heart muscle function."

hope this helps...