Day 3

Branch bundle block simplified

by AgentX86 - 2020-08-30 17:56:36

A "bundle" is a group of nerves that form electricl pathways in the heart. If one looked at the wiring diagram of the lower half of the heart, the atrioventricular node connects the atria (top half) ot the ventricles (bottom half) of the heart. The AV node is connected to the "bundle of HIS", which goes down the inside (between the left and right ventricles) of the heart.  The bundle of His splits into the "left bundle branch" and "right bundle branch" which take the electrical impulse up the left and right side of the heart.  In your case, one (or both) of these bundles of nerves isn't working properly. Your pacemaker replaces this faulty"wire".

I see you're interested in why people get CRT pacemakers and some don't.  Two-lead pacemakers have the second lead in the right ventricle.  This causes a delay in the electrical signal from the right ventricle to the left so the heart is out of sync. 

Think about squeezing one side of a water baloon.  The other side bulges out, then the other side contracts, bulging out the first.  In some, this causes the heart to enlarge, causing a drop in the efficiency of the heart.  A CRT pacemaker has a lead in both ventricles so they beat together and kinda support each other.  The good news is that this condition (cardiomyopathy) is usually correctable with the CRT pacemaker.

I see you're interested in knowing why people have CRTs.  The above is the most common reason - their heart has shown some reduction in efficiency, as measure but one's LVEF (left ventrical ejection fraction).  When this measure gets down to some level, a CRT is called for.  In my case, I had an AV ablation (connection from the upper half and lower half intentionally cut) and the CRT was inserted as a preventative, before it was needed to reverse cardiomyopathy.  Mine is a little unusual in that I don't have an atrial lead, just a lead in each ventricle.

Hello and welcome Indianapacer

by Gemita - 2020-08-30 19:54:58

Yes pacemakers and hearts ♥️ that need pacemakers are complicated but don’t feel overwhelmed because everything will become clearer.  There is a lot to learn but we often cover the same subjects because members are dealing with many common problems.

Day 3 with your new friend, so you are at the start of your journey.  Are you able to tell us what pacemaker you have ?  I have a Medtronic dual chamber pacemaker for bradycardia (slow heart rate) too, as well as Tachy/Brady syndrome.  Bradycardia is defined as any heart rate below 60 bpm, although my doctors were not really concerned until my heart rate fell considerably lower and I became “symptomatic”.  A normal heart rate should ideally be between 60-80 bpm although may still be considered normal up to 100 bpm.  Over 100 bpm would be Tachycardia.  As a matter of fact I too have Bundle Branch Blocks (both right and left Bundle branches are affected) but this at present is only happening intermittently.  

Bundle branch block is a delay or blockage along the pathway that electrical impulses travel to make your heart beat. It sometimes makes it harder for your heart to pump blood efficiently through your body.  This delay or blockage can occur either in the left or right bundle Branch. My doctors looked for causes initially, especially coronary artery disease, but found no significant evidence of this, although I do have a few insignificant leaky heart valves/calcium deposits, but I am 71.

A brief description of how our hearts beat:  The Sinoatrial (sinus) node (1) initiates an electrical impulse that flows through the right and left atria (2) making them contract.  When the electrical impulse reaches the atrioventricular node (3) it is delayed slightly.  The impulse then travels down the bundle of His (4), which divides into the right bundle branch for the right ventricle (5) and the left bundle branch for the left ventricle (5).  The impulse then spreads through the ventricles, making them contract.

I have tried posting a diagram of the heart which accompanies the description given above of how the heart beats but having difficulties doing so, so I have posted a link below instead which you can copy/paste into your browser if you are interested.  Good luck and happy 😊 learning

https://www.msdmanuals.com/home/heart-and-blood-vessel-disorders/abnormal-heart-rhythms/bundle-branch-block