146 Myocardial Disease

Question 1

Mech: Congestive/dilated cardiomyopathy

Answer 1

• •The sliding filament theory suggests that over a range of stretch maximal tension goes up with length because of increased available cross-link sites between actin & myosin
• •The heart can, however, be over stretched
  
  • –A greatly increased residual blood volume causes cardiac dilation and ultimately dilated cardiomyopathy resulting in reduced function
  • –At some point insufficient tension can be generated to compensate for the dilated chamber. Such hearts work harder and ultimately fail

A remarkably heterogeneous set of rare genetic variants yields a single DCM phenotype

Question 2

Mech: hyptertrophic cardiomyopathy

Answer 2

• •Uncommon with occurrence of 0.02 to 0.2%
• •A hypertrophied and non-dilated left ventricle in the absence of another disease
• •Impaired diastolic function
• •Small LV cavity, asymmetrical septal hypertrophy (ASH), systolic anterior motion of the mitral valve leaflet (SAM)

Familial HCM:

•Most common cause of sudden death in athletes

All gene mutations are in the sarcomere

Question 3

Mech: restrictive cardiomyopathy

Answer 3

• •Hallmark: abnormal diastolic function
• •Rigid ventricular wall with impaired ventricular filling
• •Bear some functional resemblance to constrictive pericarditis
• •Importance lies in its differentiation from operable constrictive pericarditis

Question 4

Heart: Pericardial Layers

Answer 4

Question 5

Indications for endomyocardial biopsy

Answer 5

Grading of rejection in cardiac recipients

Grading of anthracycline cardiotoxicity

Diagnosis of myocarditis

Confirmation of primary cardiomyopathy

Diagnosis of specific heart muscle disease (amyloid, sarcoid, etc)

Restrictive vs constrictive heart disease

Question 6

Cardiomyopathy

Answer 6

Definition:

•“A primary disorder of the heart muscle that causes abnormal myocardial performance and is not the result of disease or dysfunction of other cardiac structures … myocardial infarction, systemic hypertension, valvular stenosis or regurgitation”

Question 7

Pathological Classification of Cardiomyopathies

Answer 7

Question 8

Sudden cardiac death

Answer 8

•Definitions:

–Unexpected death from cardiac causes early after symptom onset (usually within 1 hour) or without the onset of symptoms

–

•Strikes 300,000 to 400,000 individuals annually in US; accounts for 50% of all cardiac deaths

•

• Often the first clinical manifestation of IHD
• Coronary atherosclerotic heart disease is the most common structural abnormality associated with SCD

–Up to 80% of all SCD’s in the US are due to consequences of coronary atherosclerosis

• Cardiomyopathies account for 10-15% of SCD’s
• Remaining diverse etiologies account for only 5-10% of SCD’s

Question 9

Arrythmogenic Cardiomyopathy

Answer 9

• Sarcoid: predelection for AV conduction system

Question 10

Idiopathic Dilated Cardiomyopathy

Answer 10

• A disease of unknown etiology that principally affects the myocardium
• LV dilatation and systolic dysfunction
• Pathology

–increased heart size and weight

–ventricular dilatation, normal wall thickness

–heart dysfunction out of portion to fibrosis

Question 11

Specific Heart Muscle Disease

(Secondary Cardiomyopathy in Old Terminology)

Answer 11

Be aware of:

1. Cardiac amyloidosis (present as restrictive pattern)
2. Sarcoidosis
3. Alcoholic cardiomyopathy
4. myocarditis

Question 12

Important Causes of Myocarditis

Answer 12

• •Infection
  
  • –Viral
    
    • ​•Coxsackie (A, B)
    • Cytomegalovirus
  • –Bacterial, rickettsial, spirochetal
    
    • Chagas disease
    • Toxoplasmosis
  • –Protozoal, Metazoal
  • –Fungal
• •Toxic
  
  • –anthracyclines, catecholamines, Interleukin-2, alpha2 interferon
• •Hypersensitivity