Pathology of cardiomyopathy

Question 1

What is Left ventricular noncompaction?

Answer 1

A disorder where the left ventricular myocardium appears spongy and this is a congenital disorder with heart failure or arrhythmias.

Question 2

Gene mutations affecting myocardial ion channel function can cause:

Answer 2

Sudden cardiac death

Question 3

Determine the causes of dilated cardiomyopathy and hypertrophic cardiomyopathy:

Answer 3

Dilated
20-50% are genetic causes
And the rest are non genetic causes (alcohol, myocarditis, peri partum, idiopathic)

Hypertrophic
100% genetic causes (sarcomeric proteins)

Question 4

What are the key proteins mutated in dilated/hypertrophic cardiomyopathies?

Answer 4

• Dilated: sarcoglycan, dystrophin, desmin, mitochondrial proteins, titin, lamin
• hypertrophic: myosin light chains, myosin binding protein C
• both: tropinin I/T, tropomyosin, actin, myosin heavy chain

Question 5

Arrhythmogenic right ventricular cardiomyopathy happens due to:
How does it appear histologically:

Answer 5

Defective cell adhesion proteins in the Desmosomes that link adjacent cardiac myocytes

Histologic section shows that the myocardium was replaced by fibrosis and fat

Question 6

List 2 secondary causes of hypertrophic cardiomyopathy:

Answer 6

• Deposition diseases of the heart (amyloidosis)

- Hypertensive heart disease.

Question 7

What is the most common cardiovascular disorder caused by single gene mutations?

Answer 7

Hypertrophic cardiomyopathy

Question 8

List macroscopic and microscopic changes for hypertrophic cardiomyopathy:

Answer 8

Macroscopic: asymmetric septal hypertrophic (ventricular septum is thicker than the left ventricular wall) and appears like a banana shape

Microscopic: extensive myocyte hypertrophy, myofiber disarray, interstitial and replacement fibrosis.

Question 9

What is restrictive cardiomyopathy, why does it happen, and what are the pathological changes observed?

Answer 9

It is a decrease in ventricular compliance resulting in impaired ventricular filling during diastole.
(Similar symptoms as pericarditis or HCM)
It is caused by radiation fibrosis or amyloidosis or sarcoidosis or a metastatic tumor or idiopathic.
Some of the pathological changes observed include a stiff myocardium, no change in ventricle size, and bilateral dilation could happen.
Microscopically we see diffuse interstitial fibrosis and a specific etiology like amyloidosis.

Question 10

What is myocarditis and why does it happen?

Answer 10

Myocarditis is the inflammation of the muscle cells of the heart
2 types:
- Myocarditis caused by infections like viruses/rickettsia/bacteria/Protozoa/helminths
- Myocarditis caused by immune mediated reactions like rheumatic fever/SLE/drug hypersensitivity

Question 11

A myofiber distended with trypanosomes along with inflammation and necrosis along the myofibers is:

Answer 11

Chagas’ disease

Question 12

Seeing interstitial inflammatory infiltrate eosinophils and mononuclear inflammatory cells suggests:

Answer 12

Hypersensitivity myocarditis

Question 13

Seeing mononuclear inflammatory infiltrate with lymphocytes and macrophages and multinucleated giant cells suggest of:

Answer 13

Giant cell myocarditis

Question 14

List some of the cardiotoxic drugs:

Answer 14

Chemotherapeutic agents
Tyrosine kinase inhibitors
Anthracycline toxicity
Lithium
Phenothiazines
Chloroquine
Cocaine
Doxorubicin