PATHOLOGY LAB 2

CARDIOMYOPATHIES AND PERICARDIAL DISEASES

J.P. Veinot M.D. FRCPC

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This lab will consist of review and discussion of kodachrome slides with an instructor.

MYOCARDIAL DISEASE - CARDIOMYOPATHIES

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MYOCARDIAL RESPONSE TO INJURY:

1.The heart has several responses to injury, independent of the cause of the damage. The most common include dilatation of a chamber, hypertrophy of a chamber and fibrosis. Myocardial infarcts would be an example of myocardial fibrosis. The regenerative capability of the myocardium is limited.

The heart in the slide came from a 24 year old male patient with no other known medical problems. He presented with shortness of breath. This heart in cross-section has dilated and hypertrophied right and left ventricles. Normal heart for comparison ; Dilatated heart

a. Hypertrophy of a heart chamber implies what?

b. Dilation of a heart chamber implies what?

c. What sort of pathophysiologic abnormalities and clinical signs and symptoms would a patient with a heart like this manifest ?

pathophysiology ?
signs ?
symptoms ?

d. Ischemic injury is a very common form of myocardial injury and could cause a heart to have ventricular dilatation and/or hypertrophy. Ischemia may cause infarcts that are visible with the naked eye or ischemia may cause many tiny microinfarcts that can only be seen under the microscope. Both may cause changes in the ventricle dimensions.

Other non-ischemic (and non-myocardial) abnormalities of the heart can cause the ventricles to react this way. Name some.

CARDIOMYOPATHY

2. Cardiomyopathy refers to diseases that primarily affect the heart muscle - myocardial disorders. Some of these are primary cardiomyopathies while others have a secondary cause. 

The new definition defines a cardiomyopathy as a heterogenous group of diseases of the myocardium associated with mechanical or electrical dysfunction that usually (but not invariably) exhibit inappropriate ventricular hypertrophy or dilation and are due to a variety of causes that frequently are genetic.

Cardiomyopathies are either confined to the heart or are part of generalized systemic disorders often leading to cardiovascular death or progressive heart failure related disability.

 

 The classification of primary cardiomyopathies includes:

1) Genetic: HCM, ARVC, LV non-compaction, glycogen storage (PRKAG2, Danon), conduction defects, mitochondial, ion channel (LQTS, Burgada, SQTS, CVPT, Asian SUNDS)

2) Mixed: DCM, restrictive

3) Acquired: inflammatory (myocarditis), stress (tako tsubu), tachycardia induced, infant   diabetic mother

 

On a practical basis, pathology groups them into 3 groups:  

Dilated cardiomyopathy - abnormalities in systole, generally dilated chambers

Hypertrophic cardiomyopathy - abnormalities in diastole, generally hypertrophied ventricle

Restrictive cardiomyopathy - abnormalities in diastole, dilated atria usually

Molecular biology has shown us that in many of these cases of primary dilated cardiomyopathy the abnormality is with the CYTOSKELETON of the myocytes. Other research indicates there are problems or susceptibility to FREE RADICAL myocyte damage or increased APOPTOSIS of the myocytes. Many of these PRIMARY DILATED CARDIOMYOPATHIES are inherited. Dilated Cardiomyopathy

It is important to remember that coronary artery disease, valvular heart disease or systemic arterial hypertension can produce secondary changes of dilation and hypertrophy of the chambers. It is important to rule out these diseases before one diagnoses the patient with a myocyte disorder.

 

MYOCARDIUM 

3.This microscopic section shows another form of myocardial injury. Myocardial injury

a. What is it?

b. This patient was an 18 year old male who died suddenly when playing basketball. What is the pathogenesis of this form of myocardial damage?

4. This is a gross photograph of the heart from which the last slide was taken, opened at autopsy. The heart has many similarities to that of the last case of dilated cardiomyopathy. This heart is dilated and flabby. The myocardium seems pale due to inflammation and edema. Heart with myocarditis .

What abnormalities does this heart show? 

Most myocarditis is either of unknown cause or is related to viral infections.

Myocarditis may have a definite relationship with secondary dilated cardiomyopathy. In many cases of myocarditis the patient will recover, but some go on to develop a dilated cardiomyopathy. Also when one performs microscopy on hearts with dilated cardiomypathy sometimes myocarditis is present. It is now thought that the virus causes damage to the cytoskeleton of the myocyte and thus produces cardiomyopathy.

5. This is a patient with chronic systemic arterial hypertension. Hypertrophied heart

a. What is the abnormality shown?

b. What valvular lesion might result in a heart which looks similar to this? Valves

c. What would the functional effect of having a ventricle like this be?

6. Here is a heart cut in a slightly different plane. Orient the structures seen. Hypertrophic cardiomyopathy

a. What is the major abnormality and where is it located?

b. This is a case of HYPERTROPHIC CARDIOMYOPATHY. This is usually a genetically inherited disease in which the main abnormality is with ventricular diastolic function. There are symmetrical and asymmetrical types. The asymmetrical type can be associated with septal hypertrophy and with ventricular outflow obstruction. This can cause syncope or light headed spells. Sudden death is unfortunately not uncommon in this disorder. There also may be problems with arrhythmias, and heart failure. Molecular biology has found that the disorder is due to mutation in the CONTRACTILE and SARCOPLASMIC PROTEINS of the myocyte. These include myosin, tropomyosin, and troponin. Multiple mutations are described and they probably have a different prognosis.

c. What sort of pathophysiologic abnormalities would you expect such a patient to manifest?

d. What other processes could mimic this disorder, and would need to be ruled out clinically?

7. This is a case of amyloid involvement of the heart - or AMYLOID HEART MUSCLE DISEASE. amyloid

Amyloid is a type of protein which may be deposited preferentially in the myocardium, for unknown reasons. Some cases are related to multiple myeloma (plasma cell malignancy) while other types are post-inflammatory or genetic.

a. This sort of deposition makes the heart stiff and the pathophysiologic consequence is described as RESTRICTIVE (instead of DILATED or HYPERTROPHIC). What does this term 'restrictive' imply?

There are PRIMARY RESTRICTIVE CARDIOMYOPATHIES.  These are not common in North America, but are seen more in the tropics. RESTRICTIVE disorders have problems with diastolic function.

b. What sort of endocardial lesion might also produce a restrictive pattern?

PERICARDIUM

8. This is the pericardial surface of a heart. Pericarditis

a. The surface should be smooth, but instead is abnormal. How would you describe it? What term do pathologists use to describe this? Pericarditis  

b. This sort of reaction is the early stage of reaction to many injuries. List some which might cause this change.

c. Often such an inflammatory reaction is accompanied by accumulation of fluid in the pericardial space. What is such an accumulation called?

9. This is an example of TUBERCULOSIS involving the pericardial cavity. TB pericardium

a. How would you describe the abnormality?

b. What other pathology does this patient's heart show?

10. This is the lateral chest x-ray of the same patient. CXR

a. What is the abnormality?

b. What sort of pathophysiologic effect might this have?

c. What name is applied to this functional defect?

11. This is another, but different way the pericardium may be made stiff, and non-compliant.

a. What is the likely diagnosis? Pericardial met

b. Often this same problem may be accompanied, instead, by a PERICARDIAL EFFUSION. What might be a good way to make a definitive diagnosis of this clinically?

 

MISCELLANEOUS

12. This is an example of the commonest form of primary heart neoplasm. myxoma

a. What is a neoplasm?

b. What do we mean by 'primary'?

c. If we use the term 'secondary' neoplasm, what does this mean?

d. This neoplasm is a LEFT ATRIAL MYXOMA (a benign tumour). What might presenting clinical symptoms be? Do benign tumours ever harm the patient?

13. This is an AORTIC DISSECTION. The aorta has split apart along its length. In this disorder the aorta tears its inner intimal surface and blood splits the aorta media into two layers. As the blood flows, the tear and aorta split propagates and rips or tears the aorta into 2 channels. The blood in the "false' lumen may compress the vessel and cause ischemia. The blood may also rupture out the adventitia of the aorta causing hemorrhage.

Microscopy aortic dissection ; Tear aorta ; Aorta cross sections with lumen compression ; Types of aortic dissection ; Entry tear aortic dissection

The slides show how the aortic media is split into inner and outer halves where the blood has split the media layer. They show how a 'FALSE LUMEN' is produced, and show the ENTRY TEAR which is usually found somewhere in thoracic (often ascending) aorta. Entry tear

a. What conditions might predispose to a dissection?

b. What sort of effects or complications might occur after a dissection?

c. Some people call these 'dissecting aneurysms' but this is a bad term - why?

d. With which tests can one diagnose a dissection clinically?