Introduction

Myocardial diseases are related to the general term of muscle disease, myopathy (Greek myo- "muscle" + pathia "suffering"), therefore, cardiomyopathy is a disease of the heart muscle.

Cardiomyopathies are generally categorized as pathology affecting the myocardium from a primary or secondary cause and the outcome is impaired cardiac function.

Primary myocardial diseases arising from genetic origins are incurable but the condition can be treated through pharmacological, interventional, or surgical support.

These diseases fall into subcategories which lead to congestive heart failure and death.

Primary myocardial diseases are considered more genetic in origin. Their notable etiologies include:

  • Hypertrophic cardiomyopathies - thickened muscle, inherited, acquired
  • Dilated cardiomyopathies - thinning LV, idiopathic, ischemic, inherited
  • Restrictive cardiomyopathies - rigid or less elastic, idiopathic, inherited, systemic
  • Infiltrative diseases
  • Storage diseases
  • Arrhythmia-Induced cardiomyopathies - dysrhythmia, idiopathic, inherited
  • Non-compaction (described but not classified by the World Health Organization (WHO))

In some references, takotsubo may be classified as a genetically passed on trait.

Secondary myocardial diseases may be reversible if the precipitating conditions are treated and resolved.

Secondary myocardial diseases are generally acquired (note: research is now identifying many diseases as having a genetic component) and their etiologies are:

  • Alcohol
  • Hypertension
  • Infection
  • Ischemia
  • Metabolic cardiomyopathy
  • Valvular disease
  • Peripartum cardiomyopathy
  • Takotsubo cardiomyopathy
  • Tachycardia

Description of Primary and Secondary Causes

Diseases of the myocardium often fall into the "Big Three" forms of cardiomyopathies. Those are hypertrophic, dilated, and restrictive. The two other forms are arrhythmic and non-compaction which are not as common.

The chart describes the overall appearance of each pathology and possible outcomes.

Condition HCM DCM RCM ARRY NCCM
Hypertension        
Valvular      
Alcohol        
Ischemia        
Infectious        
Metabolic        
Peripartum        
Takotsubo        
Tachycardia (TIC)        
Spongiform or
Non-Compaction
     

 

Primary Myocardial Diseases - most common causes
       
  Infiltrative
  •  Amyloidosis •• A disorder of protein metabolism which results in protein deposition in the interstitial infiltration of the myocardium[2].
  •  Sarcoidosis •• A granulomatous disease of unknown cause that results in an abnormal collection of inflammatory cells primarily found in the lungs and lymph nodes.
  Non-infiltrative
  •  Idiopathic The term literally means "from unknown cause".
  •  Familial/genetic An autosomal dominant disorder that does not always progress to a pathologic stage.
  •  Diabetic The inability to produce insulin to control blood sugar leading to accumulation of lipids in the endothelial layers of blood vessels.
  •  Scleroderma An abnormal growth of connective tissue which is believed to occur as a result of the body's immune system attacking healthy tissues.
  Endomyocardial
  •  Hypereosinophilia•• A disease characterized by a persistently elevated eosinophil (a component of blood) count (≥ 1500 eosinophils/mm³) also known as Löffler's endocarditis.
  •  Carcinoid A disease characterized by thickening and retraction of the tricuspid valve resulting in stenosis and regurgitation, pulmonic valve retraction and stenosis, right sided endocardial surfaces, and left sided cardiac valves (uncommon).

The right heart is mostly affected due to systemic tumor substances being inactivated by the lungs.
  •  Fibrosis The histological assessment of the macroscopic and microscopic presence of scarring and interstitial plexiform (network-like) fibrosis.
  •  Radiation The side effect of radiation therapy in the treatment of patients with cancer, can cause damage to the heart and pericardium.
  •  Drug induced The toxic effect of some drugs such as cocaine, glucocorticoids, lipid-lowering drugs, antimalarials, and colchicine can cause direct myotoxicity.
  •  Metastatic cancers The spread of cancer cells, usually from the liver, cause growth inducing serotonin to spread to the heart leading to cardiac valves and tissues.
       
  Storage Diseases
  •  Hemochromatosis •• The abnormal accumulation of iron in parenchymal organs, leading to organ toxicity, and myocardial rigidity.
  •  Glycogen[1] Genetic deficiency or absence of specific enzymes required for glycogen breakdown.
       
    •• Most common causes of RCM

Specific determination of the forms of infiltrative processes are achieved by biopsy.

 
   
 
 
 
 
 
 
 
 
 
 
   
   
Classification and Description

Hypertension

Hypertension cardiomyopathy is due to systemic elevation of blood pressure and can be both inherited or acquired and presents as a abnormal thickening of the left ventricle with or without decreased ventricular dysfunction. This form of myocardial disease is also considered age related with some thickening over time.

Systemic elevation of blood pressure due to increased vascular resistance increases the workload on the heart causing changes in the size and number of myocites in cardiac muscle. The changes in cardiac thickness and dimensions cause structural abnormalities that can lead to electrophysiologic conduction aberrations, cardiac arrhythmias like atrial fibrillation, coronary artery disease, systolic and diastolic dysfunction, myocardial infarction, renal artery stenosis, and congestive heart failure.

Electrocardiographic Findings

  • The most commonly used are the Sokolov-Lyon criteria (S wave depth in V1 + tallest R wave height in V5-V6 > 35 mm).
  • ST elevation in the right precordial leads V1-3 (“discordant” to the deep S waves).
  • ST segment depression and T wave inversion in the left-sided leads

Echocardiographic Findings

These criteria are often seen in left ventricular hypertrophy, however, overall evaluation of the heart must be performed in order to determine the root cause of such changes. Measurements may identify the diagnosis as mild, moderate, to severe disease.

2D/M-Mode

  • Concentric global left ventricular thickening with "ground glass" appearance
  • Left atrial enlargement
  • Increased left ventricular mass
  • Preserved or enhanced global left ventricular function (early stage)
  • Mid cavity obliteration
  • IVS thickening
  • Right ventricular hypertrophy
  • Mitral valve changes (mitral annulus calcification)
  • Decreased mitral valve excursion
  • Left ventricular diastolic dysfunction
  • Aortic valve sclerosis
  • Aortic root dilatation/calcification
  • Left ventricular dilatation and reduced ejection fraction (late stage)

Doppler

  • Increased left ventricular outflow tract velocities
  • "Dagger shaped" CW profile
  • Mitral valve E/A velocity
  • Possible presence of aortic regurgitation, mitral regurgitation

Morphological changes affect the mean LV-mitral valve angle leading to Doppler mitral inflow and also a greater mean value of LV-aortic root angle which affects flow through the LVOT.

Case study video showing concentric left ventricular hypertrophy from long standing hypertension.



Valvular Disease

Valvular insufficiency and/or stenosis etiologies pose different effects based on the conditions of the valves and their place in the cardiopulmonary system. The disease is hereditary and/or acquired.

Congenital valvular heart disease is a complex array of conditions that occur in the development of the heart beginning at embryogenesis. These conditions will be reviewed in the Congenital Heart Disease Series with the exception of congenital heart diseases in the adult patient.

Congenital bicuspid aortic valve presents with a normal annulus but commisural fusion, prominent raphae, and "football shaped" orifice in systole. Note: coarctation of the aorta is a co-morbidity in bicuspid aortic valve.

Acquired valvular disease is often due to infection, lifestyle, or heriditary conditions:

A patient with multi-valvular disease


Ischemic

Usually attributed to coronary artery disease, ischemia is due to atherosclerosis in the coronary arteries or in the microvasculature or other obstruction preventing adequate perfusion.

Ischemia may be due to long term coronary artery disease, acute coronary syndrome, or previous myocardial infarction or extensive ventricular remodeling.

The diagnosis lies in the medical history, signs and symptoms, and diagnostic tools such as blood chemistry, electrocardiography, magnetic resonance imaging, cardiac CT imaging, echocardiography, or angiography should the symptoms become severe.

Case Study Video

 

 
   
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