Progressive AV heartblock due to Nkx2.5 gene defect

[mommymic]

My husband and 3 of my 4 kids have NKX2.5 "Tin Man" and my husband passed out when he had a 13 sec heartblock a few years ago at age 35yr and had a pacer placed. My son is 13yr and had Mobitz type 2 and is blocking several 2.5 secs and a couple 3.5 secs over a 24 he holter and his cardiolgist wants to pace him now but my husband wants another opinion. My son is not passing out but gets dizzy with blocked beats. My younger kids are early on still and dont need interevention yet. Do you think its time to pace my son? Thanks, Michelle

[mommymic]

Thanks for your advice. Just to add a couple things, my son, daughter and hubby also have a bicuspid aortic value and my son had a VSD that closed in addition to the AV hearrtblock. I thought about waiting until over Christmas break for the pacer but I dont want to risk his having a long block and passing out.
Thanks again,
Michelle

[Jeffrey R Boris, M.D.]

Dear Michelle,

Before I answer your question, I’m going to explain some of the terminology that you are using for our other readers.  NKX2.5 is a gene that encompasses a specific set of mutations that has been found to be occasionally associated with several types of structural and functional cardiac defects.  These include atrial septal defects, pulmonary stenosis, ventricular septal defect, tetralogy of Fallot, Ebstein’s anomaly of the tricuspid valve, and, as in your family’s case, progressive atrioventricular block.  Atrioventricular block occurs when the single electrical connection between the atria, the upper chambers, and the ventricles, the lower chambers, is partially or completely lost.  Your son has second degree atrioventricular block type II, or so-called Mobitz type II.  Of the 4 types of atrioventricular block, this is just below third degree, or complete, atrioventricular block, which is the worst type.

I don’t have your son’s Holter monitor or his ECG to evaluate to see how many criteria he meets to place a pacemaker.  However, based on what I am seeing here, with symptomatic pauses that are fairly long AND knowing that his heart block will be progressive, it certainly does sound like it is time to put in a pacemaker.  Obviously, this decision has to be balanced with the understanding that it will be a lifelong requirement, and neither the pacemaker generator nor the leads will last forever, so trying to go as long as you can without is certainly desirable.  Yet, with these findings, you may only buy him 6-12 extra months and, meanwhile, it may put him at a bit of risk of suddenly developing complete atrioventricular block.