What is Hypertrophic Obstructive Cardiomyopathy (HOCM) ?

I assume some of my blog posts over the next little while may have something to do with Susan's Heart Condition.  I thought it would be a good idea to back up and explain exactly what she is dealing with.

Susan's condition is a congenital heart defect called Hypertrophic Obstructive Cardiomyopathy (HOCM).  Congenital Defects are common and effect approximately 1 in 100 babies that are born.  Congenital heart defects range greatly in severity and complexity.  Some defects may be as straight forward as a hole in the heart between the heart chambers.  Sometimes these "minor" issues resolve themselves as the child grows and require no intervention.  Other congenital defects are severe and require massive interventions.   This is why pediatric cardiology and surgical interventions can be so complicated.  The medical team can face an almost infinite amount of scenarios.  In some cases they literally have to invent new treatments or surgical procedures based on the patients need.  Nothing cookie cutter about these very complex kids.

What is HOCM?

Hypertrophic Obstructive Cardiomyopathy combines three issues with the heart.  Hypertrophy, an obstruction, and cardiomyopathy.  Here is an explanation of each issue that comprises HOCM.

Hypertrophy

TOP: Normal Heart

BOTTOM: Hypertrophic

Hypertrophy simply meaning thick.  The wall of the heart is thick and inelastic.  What you need to remember is that the heart is a pump.  The walls of the heart should be very elastic in order to function.  With HOCM the myocardium becomes thick and inelastic (as shown in the picture to the left).  Imagine a tire tube.  A tire tube is easy to form and as you inflate it with air it changes shape very easily.  That would be similar to a normal heart; very pliable and elastic.  As you picture a tire tube, contrast that with the tire the tire tube might go into.  The rubber of the tire is thick and firm.  Does it change shape as you fill it with air?  Yes...but it changes shape slowly and requires a great deal more air pressure to change the shape.  This is very similar to the HOCM heart.  Very thick walls that takes a great deal of effort and time to expand and contract.





Cardiomyopathy

A cardiomyopathy is very simply a disease that effects the muscle of the heart. In HOCM, the normally congruent alignment of the muscle cells are malformed.  The cells are out of alignment and enlarged.  This is what causes the thickening of the walls of the heart. In the diagram below you can easily see the issue when you compare normal heart muscle cells in contrast to the disarray of the cells with someone who has HOCM,  In addition to the thickness of the myocardium that this causes it also can significantly weaken the muscle.  So you are left dealing with two issues with the heart.  The thickness of the heart and also a weak heart.

The important thing to keep in mind when you consider the thickness of the wall of the heart and the inherent weakness in the muscle is that there is no treatment to correct this.  The issue is at a cellular level and no medication or surgery is going to alleviate the root cause  It is what it is.  Of course this all depends on the severity of the condition.  Many HOCM patients will utilize drug therapy and can live relatively normal lives with some restrictions.  Others are not so fortunate.

Obstruction

The third challenge that we have to contend with is the possibility of this "thick" heart creating a physical obstruction of  blood flow.  If the muscle grows in such a way that it obstructs flow or interferes with the operation of a valve this can cause other issues and symptoms.  It is safe to say this is not a good thing.  There are some treatments for an obstruction.  One treatment is the septal myectomy (shown left) that physically removes the obstruction.  The diagram shows and example of what an obstruction may look like and how a septal myectomy would be performed.  There is no pretty way to describe this.  You crack the chest, go in, and remove the obstruction with a scalpel.

This is the surgery that Susan had in 2009.  The effect she experienced was immediate.  However, Since that time, the relief that she felt has unfortunately been short lived.  She has been steadily degrading ever since.


Next Steps:

As I have described HOCM, it becomes apparent that many of the treatments are somewhat limited.  Drug therapies, surgeries, and other procedures do provide some relief.  Our referral to the Mazankowski Heart Institute in Edmonton will provide another set of eyes to look at Susan's condition and if there is any treatment that may give some relief.  There is some discussion about another septal myectomy or an ablation procedure.  At this point it would be premature to assume anything.  What we are doing right now is diagnostic and about gathering information.  Decision making will come later.

The Elephant in the Room

Many people who know our story, are aware that Russell has a heart transplant and they immediately ask the question.  Is "transplant" an option for Susan?  At this point...No.  This is part of the harsh reality of the transplant option.  Because supply of donors is so limited transplants are reserved for those with the greatest need.  In essence, you have to be extremely ill to get listed for transplant.  Not a road that anyone would choose.  We also are well aware of this journey having been through it with Russell.  There would be many hurdles to cross and different (more radical) treatments that would be considered first.  If you asked Susan if she would want a transplant, she would likely say "No." The reason being is that she knows what it takes to get there.  Not something she would want to endure.  In discussions with our Doctors, transplant has come up in the conversation but at this point it is not being considered.  This conversation would change quickly if Susan's condition were to suddenly worsen.  Then all bets are off.  As it stands right now we are trying to get information and investigate what is going on.  Possible treatments will be discussed later.

For people who have control issues; this is likely a process that they would not do well with.