Myocytes have decreased contractile function (weak squeeze)
The myocytes contract normally, however cannot fully relax. This leaves the ventricles "stiff" and unable to fill properly.
Characterized by enlargement of the ventricular chambers.
Chief hemodynamic disturbance is systolic impairment.
Causes of Dilated Cardiomyopathy
Primary - idiopathic, genetic, and peripartum
Secondary - infection (myocarditis), toxins, inflammatory diseases, metabolic
Inflammation of the myocardium (often from infectious agents).
Usually self-limiting, but can result in dilated cardiomyopathy.
Presents with heart failure symptoms between the last month of pregnancy and up to 6 months post-partum.
Unclear etiology, but risk factors include older age, african descent, and multiple pregnancies.
50% have a return to normal ventricular function.
Pathophysiology of Dilated Cardiomyopathy
Inflammatory process leads to decreased contractile function...
Which leads to decreased stroke volume...
Which leads to increased left ventricular diastolic pressure...
Which leads to a dilated ventricle...
Which leads to more decreased contractile function...
Heart Failure Symptoms
PND (noctunal dyspnea)
Heart Failure Signs
Low urine output
Palpable / Loud S2
Hypertrophic Cardiomyopathy (HCM)
Thickened myocytes contract well but are "stiff" and cannot relax. This leads to problems filling the ventricle.
Most common cause of sudden death in athletes.
Incidence of 1/500 --> Autosomal Dominant
Characterized by asymmetric or symmetric thickening of ventricular walls
Hypertrophic Obstructive Cardiomyopathy (HOCM)
When there is dynamic obstruction of the LV outflow tract by the mitral valve leaflet. The mitral valve physically blocks the outflow tract and prevents blood from leaving into the aorta.
Hypertrophic Cardiomyopathy - Treatment
Decrease contractility - B-blockers, CCB
Possible myomectomy or septal ablation
Avoid low preload or afterload
Characterized by abnormally rigid (not necessarily thick) ventricular walls. This causes abnormal filling because of the lack of contractility.
Less common but is the extreme of diastolic dysfunction.
Most common cause is amyloidosis.
Most common in primary (AL) form of amyloid.
Results in reduced ventricular compliance and increased LVEDP. This in turn, increases pulmonary venous pressure, as well as decreases stroke volume and cardiac output.
Restrictive Cardiomyopathy - Physical Exam
Elevated JVP with prominant x and y
Low voltages on ECG