Dilated cardiomyopathy

Question 1

What are some symptoms of dilated cardiomyopathy?

Answer 1

Dyspnoea

Orthopnoea

Fatigue

Question 2

What are some signs of dilated cardiomyopathy?

Answer 2

Look for signs of volume overload, HF

Signs of hypoxia (clubbing, cyanosis)

JVP, pulsatile liver, peripheral oedema

Right ventricular heave/displaced apex beat

Question 3

Is there wall hypertrophy in dilated cardiomyopathy?

Answer 3

No

Typically chamber size will increase but not the size of the wall

Question 4

What is a consequence of dilated cardiomyopathy?

Answer 4

Valve incompetence

Question 5

How does dilated cardiomyopathy interact with the Frank-Starling law?

Answer 5

Says that as cardiac muscle is stretched, it performs better (increased sarcomere length exposes more cross-bridges to Ca2+, increasing sensitivity). Past a certain point however it performs worse

Thus, eventually in cardiomyopathy the heart enters heart failure

Question 6

What are some examples of the history you may get from a patient with dilated cardiomyopathy?

Answer 6

Orthopnoea, dyspnoea on exertion

Past history of HTN, IHD or cardiomyopathy

Question 7

What investigations could you order in dilated cardiomyopathy?

Answer 7

CXR – look for dilation of heart

ECG – will show arrhythmias, LVH

Echocardiogram

Question 8

What would an echocardiogram tell you in dilated cardiomyopathy?

Answer 8

Detects valvular disease

Whether LV function is globally impaired (idiopathic dilated cardiomyopathy) or whether there is segmental wall abnormalities (ie in IHD)

Ejection fraction can be estimated

Question 9

in dilated cardiomyopathy, at what ejection fraction should treatment begin?

Question 10

What are the main drugs to be given in dilated cardiomyopathy?

Answer 10

Diuretics

Usually Lasix (frusemide) plus a potassium sparing diuretic

Also, drugs to treat the potential cause of the volume/pressure overload

Question 11

What are the factors that make up total cardiac output?

Answer 11

Input to the heart (preload)

Heart rate

Strength of contraction (contractility)

Ejection fraction

Resistance to pumping (afterload)

Question 12

What are the general parts of each of the four classes of cardiac failure?

Answer 12

Class 1 to class 4, basically class 1 is no limitations in activity, through to class 4 where there is discomfort with all activity and symptoms at rest

Question 13

When do you add loop diuretics or B blockers in cardiac failure?

Answer 13

When there is slight limitation in activity because of symptoms (fatigue, palpitations, dyspnoea, angina)

Class 2 cardiac failure

Question 14

When do you add spironolactone or digoxin in cardiac failure?

Answer 14

When there is marked limitation in activity because of symptoms

Class 3 heart failure

Question 15

When do you consider transplantation, short term treatment with B agonists or PDE inhibitors in cardiac failure?

Answer 15

When there are symptoms of cardiac failure even at rest, and discomfort with any and all activity

Class 4 cardiac failure

Question 16

How can we measure RVEDP?

Answer 16

Catheter inserted via a vein across the tricuspid valve into RA

RAEDP = RVEDP

Question 17

How can we measure LVEDP?

Answer 17

Catheter inserted via an artery across the aorta

Also, pulmonary artery wedge pressure?

Question 18

Why is it important to assess EDP in dilated cardiomyopathy?

Answer 18

Because of pressure overload causing CF

Indicates the severity of cardiac failure

Question 19

What are the two ways by which peripheral oedema can develop?

Answer 19

Decreased oncotic pressure, ie liver failure

Increased hydrostatic pressure, ie higher arterial or venous pressures causing less fluid reabsorption

Question 20

Explain why water retention occurs in CF

Answer 20

As CF falls, LVEDP can be increased to pull CO back to normal values