(cardioresp) valvular disease and heart failure

Question 1

how do you calculate cardiac output?

Answer 1

CO = HR x SV

where HR = heart rate and SV = stroke volume

Question 2

how do you calculate stroke volume?

Answer 2

SV = EDV - ESV

where EDV = end diastolic volume and ESV = end systolic volume

Question 3

what is cardiac output?

Answer 3

the volume of blood pumped out by the heart per minute (litres/min but can also be cm3/min)

Question 4

what are the units for cardiac output?

Answer 4

litres per minute OR cm3 per minute

Question 5

how do you calculate ejection fraction?

Answer 5

EF = (SV/EDV) x 100

where SV = stroke volume and EDV = end diastolic volume

Question 6

what is ejection fraction?

Answer 6

the volumetric fraction of blood that is ejected by the ventricles with each contraction

Question 7

how is ejection fraction given?

Answer 7

usually as a a percentage (as SV/EDV is multiplied by 100)

Question 8

how do you calculate mean arterial pressure?

Answer 8

MAP = (CO x SVR) + CVP

where CO = cardiac output, SVR = systemic vascular resistance and CVP = central venous pressure

OR (ONLY if at normal resting heart rates)

MAP = 1/3 SBP + 2/3 DBP

where SBP = systolic blood pressure and DBP = diastolic blood pressure

Question 9

what is the mean arterial pressure?

Answer 9

an average of arterial blood pressure throughout a single cardiac cycle of systole and diastole

Question 10

what is an alternative equation for mean arterial pressure?

Answer 10

MAP = 1/3 SBP + 2/3 DBP

where SBP = systolic blood pressure and DBP = diastolic blood pressure

Question 11

what is the desired range for mean arterial pressure?

Answer 11

should be >65mmHg as this represents the pressure necessary to adequately perfuse the body organs

Question 12

what are the units of mean arterial pressure?

Answer 12

mmHg

Question 13

why is it important that the mean arterial pressure is greater than 65mmHg at all times?

Answer 13

as this is the desired MAP that allows sufficient perfusion of the body’s organs

Question 14

how does the mean arterial pressure vary during exertion?

Answer 14

usually during exertion the MAP moves more closely towards an average of SP and DP instead of the usual equation (1/3 SBP + 2/3 DBP)

Question 15

what is systolic blood pressure?

Answer 15

the pressure in the arteries during ventricular contraction (i.e. during systole)

Question 16

what is diastolic blood pressure?

Answer 16

the pressure in the arteries during ventricular relaxation (i.e. during diastole)

Question 17

what is pulse pressure?

Answer 17

the difference between the systolic and the diastolic blood pressures

Question 18

what is the desired pulse pressure?

Answer 18

should be between 30-40 mmHg (along with desired systolic and diastolic blood pressures)

higher = wide pulse pressure
lower = narrow pulse pressure

Question 19

what does a narrow pulse pressure suggest (in hypotension)?

Answer 19

that there is not sufficient blood in the arteries to exert normal pressure on the artery walls

Question 20

what does a narrow pulse pressure suggest (in hypotension)?

Answer 20

that there is not sufficient blood in the arteries to exert normal pressure on the artery walls

(may be due to severe blood loss)

Question 21

what does a wide pulse pressure suggest?

Answer 21

that the heart has to work harder to pump sufficient amounts of blood around the body

may be due to a change in structure or function of the heart

Question 22

what does a narrow pulse pressure suggest (in hypotension)?

Answer 22

that there is not sufficient blood in the arteries to exert normal pressure on the artery walls

(can be due to severe blood loss)

Question 23

what does a wide pulse pressure suggest?

Answer 23

that the heart has to work harder to pump sufficient amounts of blood around the body

can be due to a change in structure or function of the heart

Question 24

what is stroke volume?

Answer 24

the volume of blood that is pumped out of the left ventricle with each systolic contraction

Question 25

what is pyrexia?

Answer 25

raised body temperature (i.e. fever)

Question 26

what is infective endocarditis?

Answer 26

inflammation of the endocardium, vascular endothelium or valves of the heart caused by viral or bacterial infection endo (inner lining), card (heart), itis (inflammation)

Question 27

what causes infective endocarditis?

Answer 27

viral or bacterial infection

Question 28

what does infective endocarditis usually affect?

Answer 28

the heart valves

Question 29

what is the most common infection in infective endocarditis?

Answer 29

Streptococci (20-40% of cases)

Question 30

how does a bacterial infection lead to infective endocarditis?

Answer 30

bacteria enter the bloodstream and form a vegetation (a bacterial infection surrounded by a layer of platelets and fibrin)

Question 31

what tests would be done to investigate infective endocarditis?

Answer 31

FBC (esp markers of infection and inflammation) blood culture ECG transoesophageal echocardiogram

Question 32

what symptoms do people with infective endocarditis present with?

Answer 32

fever, malaise, sweats and unexplained weight loss

Question 33

why is a full blood count done for an infective endocarditis patient?

Answer 33

to test for anaemia and markers of infection or inflammation

Question 34

why is a blood culture done for an infective endocarditis patient?

Answer 34

to isolate the causative organism of infective endocarditis

Question 35

why is an ECG done for an infective endocarditis patient?

Answer 35

to show a vegetation, abscess, valve perforation or dehiscence of a prosthetic valve

Question 36

what is the dehiscence of a prosthetic valve?

Answer 36

breakdown of sutures leading to partial or complete detachment of the prosthesis from annulus uncommon complication of valve replacement surgery

Question 37

what type of echocardiogram is performed on suspected infective endocarditis patients and why?

Answer 37

transoesophageal echo > transthoracic echo as transoesophageal has higher sensitivity

Question 38

what is cardiac decompensation?

Answer 38

inability of the heart to maintain adequate circulation

Question 39

what symptomatic features of cardiac decompensation?

Answer 39

shortness of breath, frequent coughing, swelling of the legs and abdomen, fatigue

Question 40

what are the clinical features of cardiac decompensation?

Answer 40

raised JVP (jugular venous pressure), lung crackles, oedema

Question 41

what are the possible complications of cardiac decompensation?

Answer 41

vascular and embolic phenomena (stroke, Janeway lesions, splinter/conjunctival haemorrhages) immunological phenomena (Osler's nodes, Roth sports)

Question 42

what part of the heart does infective endocarditis affect?

Answer 42

affects the endocardium (especially the heart valves) aortic > mitral > right-sided valves

Question 43

which heart valve is most commonly affected in infective endocarditis?

Answer 43

aortic > mitral > right-sided valves

Question 44

what is the impact of vegetation formation at the valves of the heart?

Answer 44

1) changes in valve thickness | 2) impaired ability of the valves to open/close appropriately

Question 45

how do bacteria interact with endocardium that has underlying damage in infective endocarditis?

Answer 45

more common for bacteria to attach to the endocardium if underlying damage is present

Question 46

where does vegetation formation occur most commonly?

Answer 46

at sites of turbulent blood flow (i.e. heart valves) - exacerbated if endocardium has underlying damage

Question 47

how does the risk of infective endocarditis vary for drug users?

Answer 47

increased risk of IE for IV drug users due to needle exposure as there are more opportunities for infection introduction into the body 1) exposed to bacteria on skin surface 2) exposed to bacteria on non-sterile needles

Question 48

why are IV drug users at a higher risk of infective endocarditis?

Answer 48

increased needle exposure SO more opportunities to introduce pathogens directly into the bloodstream by 1) use of non-sterile needles 2) repeat injection forming skin wounds by which bacteria on skin surface can enter

Question 49

what is the first and critical step of infective endocarditis?

Answer 49

entry of bacteria into the bloodstream

Question 50

besides IV drug users, where else can infective endocarditis be seen?

Answer 50

- as a possible complication of routine surgeries such as dental surgery - the immunocompromised OR immunosuppressed - those w congenital heart defects leading to a damaged endocardium

Question 51

which individuals are at a greater risk of infective endocarditis?

Answer 51

- IV drug users - the immunosuppressed/immunocompromised - those w congenital heart diseases that lead to a damaged endocardium

Question 52

what is hypokinesia?

Answer 52

abnormally diminished motor activity | i.e. typical habitual moments are reduced in frequency

Question 53

what is atrial fibrilllation?

Answer 53

irregular arrhythmia of the heart that can lead to clot formation

Question 54

what is dilated cardiomyopathy?

Answer 54

dilated cardiomyopathy is characterised by dilated, thin-walled cardiac chambers with reduced contractility

Question 55

describe the thickness of the cardiac walls in dilated cardiomyopathy

Answer 55

thin-walled cardiac chambers (due to dilation)

Question 56

what impact does dilated cardiomyopathy have on the heart?

Answer 56

dilation + thin walled chambers = reduced contractility of LV = reduced ejection fraction and stroke volume = inadequate perfusion of the organs = typically resulting in global hypokinesis (insufficient motor activity)

Question 57

why are the ejection fraction and stroke volume in a patient with dilated cardiomyopathy reduced?

Answer 57

reduced due to the thin-walled nature of the cardiac chambers = cannot contract with sufficient force to enable efficient perfusion of the arteries

Question 58

describe the systolic function in a patient with dilated cardiomyopathy

Answer 58

reduced | reduced contractility due to thinner walls

Question 59

what are the most common causes of dilated cardiomyopathy?

Answer 59

idiopathic genetics ``` toxins (alcohol, cardiotoxic chemo) viral infections (myocarditis) ``` pregnancy (peripartum cardiomyopathy) tachycardia-related cardiomyopathy, thyroid disease, muscular dystrophies

Question 60

how is dilated cardiomyopathy managed?

Answer 60

medical heart failure therapy - ACE inhibitors, beta-blockers, mineralocorticoid receptor antagonists, diuretics for fluid overload (ABCD) anticoagulation for atrial fibrillation cardiac devices - cardiac resynchronisation therapy/implantable cardioverter defibrillation transplant

Question 61

what kind of cardiac devices are used to correct dilated cardiomyopathy?

Answer 61

implantable cardioverter defibrillator cardiac resychronisation therapy

Question 62

why are diuretics given in dilated cardiomyopathy?

Answer 62

to correct fluid overload

Question 63

why is anticoagulation given in dilated cardiomyopathy?

Answer 63

preventative measure in case atrial fibrillation occurs

Question 64

what is the implication of dilated cardiomyopathy on patients in the future?

Answer 64

increased risk of heart failure hospitalisation cardiac arrhythmias sudden cardiac death due to ventricular arrhythmias reduced survival

Question 65

what is the value of central venous pressure usually?

Answer 65

negligible

Question 66

what is Duke's criteria?

Answer 66

set of clinical criteria for the diagnosis of infective endocarditis used to diagnose definitive, possible or rejected endocarditis (three types)

Question 67

how many cases of dilated cardiomyopathy are attributed to idiopathic caused?

Answer 67

over 50%

Question 68

what is the most common cause of dilated cardiomyopathy?

Answer 68

most of the time - unknown cause (idiopathic) but there can be underlying reasons

Question 69

how is the fluid intake managed in patients with dilated cardiomyopathy?

Answer 69

can drink to thirst

Question 70

what is Duke's criteria for definite endocarditis?

Answer 70

1) 2 major 2) 1 major and 3 minor (1-3) criteria 3) 5 minor criteria (5) + gram stain/culture from sugery

Question 71

what is Duke's criteria for possible endocarditis?

Answer 71

1) 1 major AND > 1 minor clinical criteria | 2) 3 minor

Question 72

what is Duke's criteria for rejected endocarditis?

Answer 72

resolution after less than 4 days of antibiotic treatment no evidence of infection after surgery definite or possible endocarditis criteria not met = ruled out

Question 73

what are the major symptoms for Duke's criteria?

Answer 73

(BE) ``` B = (consistently positive) blood cultures E = positive echocardiogram (abscess, dehiscence, vegetation, or new regurg murmur) ```

Question 74

what are the minor symptoms for Duke's criteria?

Answer 74

F = fever (greater than 38) I = immunological phenomena (Osler's nodes, Ruth spots) V = vascular phenomenon (emboli organs) E = echo/positive blood cultures not meeting major criteria R = risk factor present (IV drug use or predisposing heart condition)

Question 75

which genes are implicated in the development of dilated cardiomyopathy?

Answer 75

mutations in genes encoding the cardiac cytoskeletal proteins (Titin, Lamin, myosin heavy chain, Phospholamban, cardiac myosin binding protein C)

Question 76

explain how genetic mutations can lead to the development of dilated cardiomyopathy

Answer 76

genetic mutations = impaired cardiac cytoskeleton proteins = impaired myofibril formation and myocyte function = thinner, weaker cardiac muscle = ineffective contraction of the walls (as a sufficiently high force cannot be generated)