Valvular Disease

Question 1

How do you calculate cardiac output?

Answer 1

Cardiac output (CO) = heart rate (HR) x stroke volume (SV)
SV = end diastolic volume (EDV) – end systolic volume (ESV)

Question 2

How do you calculate the ejection fraction?

Answer 2

Ejection fraction (EF) = stroke volume (SV) / end diastolic volume (EDV) x 100

Question 3

How do you calculate mean arterial pressure?

Answer 3

Mean arterial pressure (MAP) = (Cardiac output (CO) x systemic vascular resistance (SVR)) + central venous pressure (CVP)
However at normal resting heart rates MAP can be estimated using systolic and diastolic pressures using the following equation. MAP = Diastolic pressure (DP) + 1/3 (Systolic pressure (SP) – DP). MAP = DP + 1/3(SP-DP).

Question 4

What is infective endocarditis?

Answer 4

Infective endocarditis is an infection of the endocardium or vascular endothelium of the heart. Usually the result of bacteria entering the blood stream and forming ”a vegetation” (a bacterial infection surrounded by a layer of platelets and fibrin) in the endocardium. Streptococci (20-40 % of cases) are the most common infection.

Question 5

How do you diagnose infective endocarditis?

Answer 5

Symptoms: Fever, malaise, sweats and unexplained weight loss
New heart murmur may be present
Blood tests: Anaemia + raised inflamm markers
Echo can show vegetation, abscess, valve perforation and/or new dehiscence of prosthetic valve.
Transoesophagel echo has higher sensitivity.

Question 6

What is cardiac decompensation?

Answer 6

Inability of the heart to maintain adequate circulation

Question 7

What are features of cardiac decompensation?

Answer 7

Symptoms include shortness of breath, frequent coughing, swelling of the legs and abdomen, fatigue
Clinical signs include raised JVP, lung crackles and oedema

Question 8

What are other complications of cardiac decompensation?

Answer 8

Vascular and embolic phenomena - stroke, Janeway lesions, splinter/ conjunctival haemorrhages
Immunological phenomena - (Osler’s nodes, Roth spots)

Question 9

What part of the heart does infective endocarditis affect?

Answer 9

Endocardium, especially the valves of the heart. Aortic valve is affected most frequently (aortic > mitral > right-sided valves).
The formation of a vegetation at the valves of the heart either results in changes to their thickness or a failure in their ability open and close appropriates. It is more common for bacteria to attach to the endocardium if underlying damage is present, and this occurs more frequently at sites of turbulent blood flow such as the valves of the heart.

Question 10

How might this vary for intravenous drug users?

Answer 10

Intravenous drug users are at increased risk of infective endocarditis due to repeated injection – potentially exposing their bloodstream to bacteria on the surface of the skin or use of non-sterile needles.

Question 11

What is the definition of dilated cardiomyopathy?

Answer 11

Dilated cardiomyopathy is characterised by dilated and thin-walled cardiac chambers with reduced contractility. Dilation of the chambers leads to reduced contractility. Echo shows a dilated left ventricle with reduced systolic function (ejection fraction) and typically global hypokinesis.

Question 12

What are the commonest causes of dilated cardiomyopathy?

Answer 12

Idiopathic, genetic, toxins (alcohol, cardiotoxic chemotherapy), pregnancy (peripartum cardiomyopathy), viral infections (myocarditis), tachycardia-related cardiomyopathy, thyroid disease, muscular dystrophies

Question 13

How is the condition managed?

Answer 13

1. Medical heart failure therapy - ACE inhibitors, beta-blockers, mineralocorticoid receptor antagonists
2. Diuretics for fluid overload
3. Anticoagulation for atrial fibrillation
4. Cardiac devices – cardiac resynchronisation therapy and/or implantable cardioverter defibrillator
5. Transplant