Cardiomyopathy

Question 1

How does chronic alcohol ingestion lead to dilated CM?

Answer 1

Toxic aldehyde metabolites cause oxidative stress, which induces cell apoptosis. Dilated CM due to alcohol use is reversible if caught early.

Question 2

Amyloidosis and what does it cause?

Answer 2

Body produces misfolded insoluble protein with beta-pleated sheets that deposit into various organs, including the heart. This makes the heart difficult to expand during diastole. Causes restrictive CM

Question 3

How does viral myocarditis present and how does it cause dilated CM?

Answer 3

Viral myocarditis is usually due to coxsackie A or B, which leads to immune mediated myocyte loss and fibrosis. It results in chest pain, arrhythmia with sudden death, or heart failure. It’s usually self-limited but can progress to dilated CM.

Question 4

What is associated with apical LV ballooning and why?

Answer 4

Stress-induced CM. When the heart contracts, neck of ventricle contracts but middle and base don’t, resulting in a ballooning shape.

Question 5

EKG findings in restrictive cardiomyopathy

Answer 5

Low voltage EKG + diminshed QRS amplitude

Question 6

What is restrictive CM and what dysfunction (diastolic/systolic) does it cause?

Answer 6

Decreased ventricular compliance (increased stiffness) resulting in diastolic dysfunction (restricts filling).

Question 7

What are the possible manifestations of hypertrophic CM?

Answer 7

Some people have normal findings in mild forms. However, progressive hypertrophic CM can be symptomatic which includes:

1) HF symptoms (e.g. SOB, rales, JVD, leg edema, S4) due to diastolic heart failure.
2) Arrhythmias (e.g. Afib)- ventricle can overgrow its blood supply and fibrose, making people susceptible.
3) Syncope with exercise- subaortic hypertrophy of ventricular septum can result in functional aortic stenosis (LVOT) that can lead to decreased CO. Also with decreased diastolic filling, low CO.
4) VT/VF arrest (sudden cardiac death)- seen in young atheletes; due to ventricular arrhythmias.
5) Angina: thicker muscle requires more blood and sometimes, supply may not meet demand.

Question 8

Etiology of hypertrophic CM

Answer 8

Usually due to autosomal dominant (with variable penetrance) mutations of sarcomere proteins. Two most commonly mutated proteins:

1) beta-myosin heavy chain
2) Myosin-binding protein C

Question 9

What is the most type of Hypertropic CM (where does hypertrophy happen) and what can this lead to?

Answer 9

interventricular septal cardiomyopathy- septum is thicker compared to lateral wall. This can lead to left ventricular outflow tract (LVOT) obstruction, in which the septum becomes so thick that it obstructs the outflow tract.

Question 10

What is dilated CM and what type of dysfunction does it cause (systolic/diastolic)

Answer 10

Dilation of all four chambers of the heart, resulting in systolic dysfunction (ventricles cannot pump).

Question 11

Etiologies of dilated CM

Answer 11

1) Genetic mutation (usually AD but can be X-linked or recessive as well)
2) Myocarditis (usually from coxsackie A or b)
3) Alcohol abuse
4) Drugs (e.g. chemotherapeutic agents like doxorubicin, cocaine)
5) Pregnancy
6) Hemochromatosis

Question 12

What are some causes of restrictive CM and which is the most common?

Answer 12

1) Amyloidosis (most common)
2) Sarcoidosis
3) Endocardial fibroelastosis (dense layer of fibroelastic tissue in endocardium)
3) Loeffler syndrome (Fibrosis of endomyocardium with eosinophilic infiltrate and eosinophilia)

Question 13

Arrhythmogenic RV Cardiomyopathy (ARVC)

Answer 13

RV free wall replaced by fibro-fatty tissue resulting in RV dysfunction, dilatation, and akinesis

Question 14

Tx of Dilated CM

Answer 14

1) Diuretics
2) Beta blockers
3) ACE inhibitors
4) Transplant/ ICD

Question 15

What heart sound can be heard in hypertrophic CM and why?

Answer 15

S4- due to atrial contraction into stiff LV

Question 16

What is used in tx of hypertrophic CM?

Answer 16

1) beta-blockers: reduce contractility → reduce obstruction
2) non-dihydropyridine CCB (e.g. verapamil)
3) ICD for high risk pts of arrhythmias

Question 17

What is an example of chemotherapeutic drug that causes dilated DM?

Answer 17

Doxorubicin

Question 18

What is the most common cause of sudden cardiac death in atheletes?

Answer 18

Hypertrophic CM

Question 19

What heart sounds are associated with LVOT obstruction?

Answer 19

1) Systolic diamond-shaped (crescendo/decrescendo) murmur at the left sternal border
2) Apical holosystolic murmur from MR

Question 20

What are the sx of LCOT obstruction?

Answer 20

1) Angina
2) Syncope
3) Exertional dyspnea

Question 21

What are ARVCs prone to and why?

Answer 21

Ventricular arrhythmias bc replacement of RV free wall by fatty tissue results in dilatatoin and akinesis of ventricle, which is a risk factor for arrhythmias.

Question 22

Pathophysiology of restrictive CM

Answer 22

1) Increased muscle stiffness/ decreased compliance leads to increased filling pressures of both ventricles + decreased ventricullar filling.
2) Increased ventricular pressure causes transmission of pressure and blood into atria and into lungs → right + left sided HF.
3) Decreased ventricular filling causes low CO.

Question 23

What are the manifestations of dilated cardiomyopathy?

Answer 23

Due to dilation of ventricles (+ atria), heart cannot pump effectively, resulting in systolic dysfunction. This leads to biventricular CHF, which causes blood to back up in the lungs and cause pulmonary edema.

Question 24

What is hypertrophic cardiomyopathy and what type of dysfunction (diastolic/systolic) does it cause?

Answer 24

Massive hypertrophy of the LV leading to decreased compliance and less filling (diastolic dysfunction).

Question 25

What is a clue for restrictive CM in echocardiography

Answer 25

Dilated atria with normal sized cavity in ventricles

Question 26

Sx of ARVC

Answer 26

Palpitations, syncope, SCD

Question 27

What is the key biopsy/ histopathological finding of hypertrophic CM?

Answer 27

Myofiber hypertrophy with disarray

Question 28

What are some complications of dilated CM? (3)

Answer 28

1) Biventricular heart failure
2) mitral and tricuspid valve regurgitation: due to stretching of valves
3) arrhythmias: due to “stretching” of conduction systems.

Question 29

What are the sx of HF due to restrictive CM and why?

Answer 29

1) JVD, hepatomegaly/ascities/peripheral edema/ pulmonary edema: rigid myocardium leads to increased diastolic ventricular pressure which backs up on each side, leading to venous congestion and sx.
2) Weakness + fatigue: ventricular rigidity prevents ventricular filling, which decreases CO, resulting in sx.

Question 30

What is LV Non-compaction CM and how does it manifest?

Answer 30

Arrested development of myocardial compaction resulting in deep intra-trabecular recesses.

Results in HF, thromboembolism, VT/VF.

Question 31

What are the physiological manifestations of LVOT obsrtuction?

Answer 31

1) Decreased cardiac output which acutely compromises brain perfusion
2) Increased after load due to LVOT leads to worsening diastolic dysfunction
3) Increased LV pressure can acutely compromise coronary perfusion
4) Increased left atrial and pulmonary venous pressure leads to worsening pulmonary vascular congestion

Question 32

What are factors that make LVOT obstruction worse?

Answer 32

1) decreased preload (e.g. dehydration): smaller LV cavity → closer walls → worse obstruction
2) Decreased afterload (e.g. vasodilator): heart contracts more vigorously due to less resistance → walls come closer together
3) Increased contractility (e.g. vigorous exercise): walls come closer together

Question 33

What is peri-partum cardiomyopathy, when does it present, and what is the prognosis?

Answer 33

Type of dilated CM toward end of pregnacnyo r in months after delivery, resulting in HF symptoms. Most recover in 6 months.

Question 34

How does hypertrophic CM affect CO and EF?

Answer 34

Decreases CO beacuse due to hypertrophy, ventricle wall becomes so tight htat it can’t fill anymore. However, usually normal EF.