Nonobstructive hypertrophic cardiomyopathy. The heart muscle is abnormally thick but not to the
extent that any part of it crowds the lower heart chambers (ventricles). The thicker muscle simply cannot relax
properly. This means that less blood can enter the chambers and less blood is
circulated to the body. Also, abnormal heart rhythms may develop. Most
people with hypertrophic cardiomyopathy have this type.
Obstructive hypertrophic cardiomyopathy. Portions of the
heart muscle become so thick that they bulge out into the lower heart chambers
(ventricles). Blocked blood flow and smaller, less effective ventricles result,
especially during exercise, when the heart has less time to relax and fill.
Thickened heart muscle may also interfere with how the heart valves open and
close, particularly the mitral valve, which divides the left upper chamber
(atrium) from the left ventricle.