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Heart Block

 The normal human heart works by sending and receiving electrical signals which tell the heart to pump blood through the body.  This electrical signal begins in the brain, sending neurological signals to the atrium of the heart (the upper chambers), and is passed down to the ventricles of the heart (the lower chambers) through a bridge that connects the two halves.  This bridge can become altered or blocked creating the heart block associated with EDMD.  This is known as Heart Block.  EDMD always affects the heart.  There are many different ways in which the heart can be effected and they are not all muscle related.  This disease can be fatal if the heart condition is undiagnosed, untreated or misdiagnosed. EDMD with the deficiency of  Emerin caused the heart to function improperly.

You can also be diagnosed with thinning heart (Cardiomyopathy) walls as a result of this disease making the annual procedure of Echo-Cardiograms necessary.

Heart Block will usually begin at “first degree” and can progress all the way to atrial standstill which means the bridge will stop working completely. Which is why a Pacemaker is required.

Heart Block is diagnosed using an EKG which is done by a Cardiologist or Electro-physiologist.  An EKG takes only a few moments to perform and is done by connecting leads, which are little stickers placed over the body including the chest, legs and arms.  Once the stickers are in place wires are clipped to the stickers which is how the EKG machine will read the heart rate.  The only way to survive a heart block is to have a pacemaker implanted.

Cardiac Issues in EDMD

Atrial Issues

The atrium (upper portion) of the heart can produce more issues that EDMD patients will need to deal with.  The atrium of the heart works by producing an electrical signal that the bottom of the heart receives.  These electrical signals tell the heart when to pump blood throughout the body.  The problem with EDMD is that somewhere in the heart there can be “extra” signals produced which is referred to an Atrial Flutter, Atrial Tachycardia and /or Supraventricular Tachycardia.  

Superventricular Tachycardia in EDMD is a random signal.  The signal can be produced anywhere in the atrium even changing its origin within the atrium.  It is unpredictable and best left treated only with beta-blocker medication or blood thinners for the blood clotting risk it produces.  Any type of ablation procedure on this type of tachycardia may pose a greater risk to the patient as it may damage the “electrical bridge” that exists between the atrium and the ventricles of the heart.   This bridge is essential for the sending of signals from the atrium to the ventricles.  The atrium in the heart acts as the regulator while the ventricle is the portion of the heart that sends the blood to the rest of the body.

Atrial Flutter

Atrial Flutter is known as a condition where the atrium of the heart produces a fast heart rhythm.  It is often temporary causing palpitations.

Atrial Tachycardia

Atrial Tachycardia presents itself with a fast rhythm in the atrium, usually being produced from a single or multiple points within the atrium.

Superventricular Tachycardia in EDMD is often a random signal.  The signal can be produced anywhere in the atrium even changing its origin within the atrium.  It is unpredictable and best left treated only with beta-blocker medication or blood thinners for the blood clotting risk it produces.  Any type of ablation procedure on this type of tachycardia may pose a greater risk to the patient as it may damage the “electrical bridge” that exists between the atrium and the ventricles of the heart.   This bridge is essential for the sending of signals from the atrium to the ventricles.  The atrium in the heart acts as the regulator while the ventricle is the portion of the heart that sends the blood to the rest of the body.

Ectopic Atrial Tachycardia

Ectopic Atrial Tachycardia is the most common form of super atrial tachycardia in children.  It is the most resistant to cardio-version techniques as it often reoccurs in the atrium.

Atrial Stand-Still

The heart will stop producing any signal in the atrium.  This event will require a pacemaker in order to keep the heart beating.  Blood thinners will be required to prevent blood clots which can form in the heart resulting in one or more strokes.  The risk of blood clots is very real in EDMD and if your doctor prescribes a blood thinner it is very important to adhere to those instructions.

Cardiomyopathy

Cardiomyopathy is a weakening of the heart wall, and can occur in EDMD.  Those with severe cases may eventually require a heart transplant.

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A great resource for learning the function of the heart, including an interactive heart diagram, can be found at http://www.bostonscientific.com/lifebeat-online/heart-smart/electrical-system.html