Hypokinetic cardiomyopathy

Hypokinetic cardiomyopathies correspond to pathologies that decrease the motion of the heart wall. In the ORCHID project, we consider two common sources of hypokinetic cardiomyopathies, namely coronary artery disease and primary myocardial dysfunction.

Coronary artery disease

  • Coronary artery disease is the most common form of cardiovascular disease.
  • The underlying cause is atherosclerosis, which is a chronic inflammatory disease of the arteries.
  • Atherosclerosis is a disease in which the immune system elicits an active inflammation within the artery wall and lipids plays a key role.
  • As the inflammation and deposition of lipids progress, an atherosclerotic plaque forms in the wall of the artery.
  • Advanced atherosclerosis plaques contain inflammtory cells, smooth muscle cells, extracellular matrix, lipids and acellular debris.
  • As the atherosclerosis plaque increases in size, it bulges into the artery lumen and causes stenosis, i.e. reduction of the artery lumen.
  • The reduction of the artery lumen causes limitations to the blood flow. This may cause symptoms in situations with increased cardiac workload (i.e. physical exercice) because the increased workload leads to increased oxygen demand but the stenosis limits the volume that can be delivered to the heart muscle supplied by the atherosclerotic artery.

  • Whenever oxygen demand exceeds oxygen delivery ischemia occurs and this manifests with chest discomfort referred to as angina pectoris.

  • A coronary angiogram is considered to be the best method of diagnosing coronary artery disease.
    • During the procedure a long, thin, flexible tube called catheter is inserted inta a blood vessel.
    • Using X-ray images as a guide, the tip of the catheter is passed up to the heart and coronary arteries.
    • a contrast medium is injected through the catheter and X-ray images (angiograms) are taken.
    • The contrast medium is visible on the angiograms, showing the blood vessels through which the fluid passes. This clearly highlights any blood vessels that are narrowed or blocked.

 

Primary myocardial dysfunction

  • Primary myocardial disease designates those conditions which affect heart muscle but spare other anatomic structures within the cardiovascular system.
  • Primary myocardial disease thus affects the heart muscle itself and is not associated with congenital, valvular, or coronary heart disease or systemic disorders.
  • Examples include the granuloma of sarcoid, the infiltrative lesions of amyloidosis, and inflammatory myocarditis following a variety of infectious illnesses.

 

Left ventricular hypertrophy

Left ventricular hypertrophy corresponds to enlargement and thickening (hypertrophy) of the walls of the left ventricle. The thickened heart wall loses elasticity, leading to increased pressure to allow the heart to fill its pumping chamber to send blood to the rest of the body.

Left ventricular hypertrophy is more common in people who have uncontrolled high blood pressure. But no matter what your blood pressure is, developing left ventricular hypertrophy puts you at higher risk of congestive heart failure and irregular heart rhythms. In the ORCHID project, we consider two common sources of left ventricular hypertrophy, namely arterial hypertension and infiltrative myocardial disease.

Arterial hypertension

  • Arterial hypertension is a disease characterized by high blood pressure.
  • Blood pressure is the physical result of the ejection of blood by the heart into the blood vessels. It is exerted on the vascular walls. It is characterized by two extreme values:
    • The high value which is measured during the contraction of the heart (systole) and which makes it possible to push the blood by the aorta towards the peripheral arteries.
    • The low value measured during the relaxation of the heart (diastole), which allows the cardiac ventricles to receive blood arriving in the atria through the vena cava and the pulmonary veins.

  • We refer to arterial hypertension when one and/or the other of these values, measured at rest, is higher than the normal values: 140 mmHg (millimeters of mercury) for the systolic pressure and 90 mmHg for the diastolic pressure.

  • The diagnosis must always be confirmed by self-measurement of blood pressure or ambulatory blood pressure measurement:
    • self-measurement of blood pressure is based on the use of a home blood pressure monitor. The patient must measure his or her blood pressure at home in a calm environment by repeating the measurement 3 times in the morning and 3 times in the evening, during 3 consecutive days (rule of 3). The diagnosis is made when the high/low values values exceed 135/85 mmHg.
    • ambulatory blood pressure involves wearing a cuff connected to an electrical device worn on the belt. The blood pressure monitor measures and records blood pressure values every quarter of an hour for 24 hours. The diagnosis is made when the average high/low values exceed 130/80 mmHg.

Infiltrative myocardial disease

  • Infiltrative cardiomyopathies are characterized by the deposition of abnormal substances that cause the ventricular walls to become progressively rigid, thereby impeding ventricular filling.
  • Some infiltrative cardiac diseases increase ventricular wall thickness, while others cause chamber enlargement with secondary wall thinning.
  • The clinical presentation, along with functional and morphologic features, often provides enough insight to establish a working diagnosis.
  • However, in most circumstances, tissue or serologic evaluation is needed to validate or clarify the cardiac diagnosis and institute appropriate therapy.
  • The table below summarizes the different common types of infiltrative cardiomyopathies:
Naming Pathology Echocardiogram
Cardiac amyloidosis Extracellular amyloid (protein aggregate) fibrils LV and RV hypertrophy; granular speckled myocardium; restricted basal longitudinal strain
Cardiac Sarcoidosis Noncaseating granulomas (pathological clusters of inflammatory cells) surrounded by fibrosis Septal thinning/thickening; noncoronary segmental wall motion abnormalities
Hemochromatosis Genetic disease that causes iron overload Diastolic disease - global systolic dysfunction
Fabry Disease Perinuclear vacuoles (small cavity) and myocardial fibrosis Concentric LV hypertrophy
Danon Disease Myocyte hypertrophy with vacuolization (creation of small cavities) Massive LV hypertrophy with possible outflow tract obstruction
Friedreich’s Ataxia Nonspecific myocyte hypertrophy and fibrosis Increased septal thickness