Stanford Cardiac Arrhythmia Service

Heart Conditions

There are many types of heart conditions that may contribute to the development of an arrhythmia. 

*Heart Disease and Stroke Statistics_2010 Update. A Report From the American Heart Association.  Circulation. 2010 Feb 23;121(7):948-54.


 Dilated cardiomyopathy can be categorized into two types:


*Maron, BJ Circulation. 1995;92:785–789.


The valves open and close quickly and efficiently to direct blood flow in the proper direction.  The heart valves may no longer close properly and may permit blood to flow backward into the heart chamber(s).  Blood flowing backward in the heart chamber is called regurgitation.  Regurgitation of the aortic and mitral valves may lead to shortness of breath  and enlargement of the left ventricle, the main pumping chamber.  Regurgitation is usually scored from mild 1+ to severe 4+.  Mild regurgitation usually does not have a significant in the overall heart pumping function called hemodynamics.  In some cases 3+ or more regurgitation may lead to the need for heart valve surgery.  The timing of surgery usually depends on the development of symptoms felt to be due to the regurgitation, decreasing function of the left ventricle which may be reflected in a decreased Ejection Fraction, or enlargement of the left ventricle.  There also may be leakiness of the right sided heart valves, the tricuspid valve and the pulmonic valve. Regurgitation may also lead to enlargement of the upper chambers, the atria, and may result in the development of atrial fibrillation.


Heart valves can also have difficulty opening fully, a condition called stenosis.  Stenosis of the aortic valve and the mitral valve are most likely to result in symptoms. Stenosis of the aortic valve results in a significant thickening of the left ventricular walls.  The two most common causes of aortic stenosis include congenital absence of one of the 3 leaflets that make up the aortic valve called a bicuspid aortic valve and the acquired thickening of the aortic valve with age.   Aortic valve replacement is usually performed when patients develop symptoms such as shortness of breath or dizziness or loss of consciousness.  Patients with aortic stenosis may develop atrial fibrillation.

Genetic:  Patients can have genetic or hereditary heart conditions that cause arrhythmias.  Some of these conditions can be caused by a genetic mutation and not be hereditary.  Long QT, Brugada Syndrome, Hypertrophic Cardiomyopathy (HCM), Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy (ARVC/C), and Familial Dilated Cardiomyopathy (DCM), are examples of inherited or familial heart conditions associated with arrhythmias.  With the advent of genetic discovery and research, more is learned about how genetics impact arrhythmias.


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