Valvular & ischaemic heart disease therapy/surgery Flashcards
Summarise the causes of cardiac ischaemia
Atherosclerosis
Embolism
Coronary thrombosis
Aortic dissection
Arteritides
Congenital
What does ‘arteritides’ mean?
Arteritis (type of vasculitis) is inflammation of the arterial walls caused by infection or autoimmunity
Can cause thrombosis which will cause Cardiac ischaemia if in coronary arteries
Summarise the clinical manifestations of Ischaemic heart disease
Angina MI Arrythmias Chronic heart failure Sudden death
Coronary artery disease (IHD) can be classed by what coronary arteries are affected
Give 2 examples of types of coronary artery disease
Left main stem stenosis - (left coronary artery stenosis)
3 vessel coronary artery disease
In 3 vessel CAD, what coronary arteries are affected?
left anterior descending
Circumflex
Right coronary artery
What is CABG?
Coronary artery bypass graft
What are the criteria for selecting patient’s for CABG?
Lung function
Hepatic function
Mental function
Heart function - LV ejection fraction > 20%
Ascending aorta
Distal coronary targets
One of the criteria for CABG patients is ‘DIstal coronary targets must be okay’
What is meant by this?
Must be suitable vessel for the bypass to be connected to
In CABG surgery, what is a Conduit?
Vessel to be used for the bypass
This can be synthetic, but is usually just a vessel from elsewhere in the body
What vessels in the body are used for Conduits?
Reversed saphenous vein - from leg
Internal mammary arteries - aka Internal thoracic arteries from chest
Radial arteries - arm
What is a ‘Median Sternotomy’?
Surgical procedure in which a vertical inline incision is made along the sternum, after which the sternum itself is divided, or “cracked”
Allows access to heart for CABG
What complications are associated with a sternotomy?
Wire infection
Painful wires
Sternal dehiscence:
- process of separation of the bony sternum
- often is accompanied by mediastinitis (infection of the deep soft tissues)
Sternal malunion:
- Sternum doesn’t join back together properly
What are the main risks to patients post cardiac surgery
Stroke
Death
Cardiac tamponade:
- accumulation of fluid in the pericardial space
How is cardiac tamponade bad for heart function?
Fluid accumulation results in reduced ventricular filling and subsequent hemodynamic compromise
How would you identify a patient with cardiac tamponade?
Raised CVP,
Raised HR
Low BP
Oliguria (don’t pass urine)
Increased oxygen requirements
Metabolic acidosis
How is cardiac tamponade fixed?
Chest reopening
What are the long term outcomes for CABG patients?
50% have no further cardiac problems in 10 years
Of the 50% that do:
- Most problems are minor and treated with medication
- 5% of patients may require a repeat CABG
Contrast valvular heart disease surgery in adults & children
Adults - Mainly aortic & mitral valve surgery
Children - All 4 valves operated on at pretty much the same frequency
What are the causes of valvular heart disease in adults?
Degenerative Congenital Infective Inflammatory LV or RV dilatation Trauma Neoplastic Paraneoplastic
What are the most common valves that are diseased/require surgery?
(in aberdeen)
Senile tricuspid AS
Bicuspid AS
Degenerative MR
The Antistreptolysin O (ASO) titre test is used to test for what?
Rheumatic fever
Why is Rheumatic fever linked to CVS disease?
RF causes pancarditis
Chronic rheumatic heart disease:
- Gradually progressive MVDx +/- AVDx
What tends to cause rheumatic fever?
Streptococcal infections
Rheumatic fever can cause a disorder characterised by uncontrollable twitching/jerking of parts of the body
What disorder is this?
Sydenham’s chorea/ St Vitus’ Dance
streptococcal infections
Why is chronic rheumatic heart disease clinically important?
Worldwide most common heart problem
Major cause of death in pregnancy
Can cause cardiac surgery to be undertaken during pregnancy
What is Endocarditis?
Infection of endocardium
What causes endocarditis?
Bacterial infection:
Strep viridans
- Most common
- SUB-ACUTE bacterial endocarditis
Staph aureus
- ACUTE bacterial endocarditis
Why does endocarditis have clinical manifestations involving heart valves?
Endocardium makes up the valves
Therefore - damage to endocardium = damage to valves
How is endocarditis treated?
Antibiotics - if bacterial
The outcomes of antibiotic treatment of Valve endocarditis vary depending on the valves that are infected
Describe the differences in outcomes
‘Native’ valve endocarditis (NVE):
- 90% success from just Abx
Prosthetic valve endocarditis (PVE)”
- 50% success from just Abx
Another factor that determines how effective antibiotic treatment for Valvular endocarditis is, is what bacteria caused the infection
Explain this
Bacterial infection of either Strep viridans or Staph aureus
Strep viridans is easier to treat so success is higher than that of Staph aureus
If antibiotics do not cure valvular endocarditis, what happens?
Surgery (if suitable)
What are the indications for surgery for endocarditis?
Severe valvular regurgitation
Large vegetations
Persistent pyrexia
Progressive renal failure
How are patients managed after they have received surgery for endocarditis?
IV antibiotics for 6 weeks post surgery
How does aortic stenosis present?
Usually through secondary effects:
- Heart failure
- Angina
- Syncope / presyncope
Incidental finding
How can aortic stenosis be identified on examination?
Auscultation:
- Systolic murmur
- Loss of aortic S2 sound (separates it from aortic sclerosis)
How can aortic stenosis be identified on an ECHO?
Left ventricular hypertrophy
Why can’t LVH be identified on palpation?
Right ventricular hypertrophy causes a palpable HEAVE
But LVH does not (usually) cause a heave
Why is an ECG useful for identifying Aortic stenosis?
AV gradient > 50mmHg = Aortic stenosis
What is the treatment for severe Aortic stenosis?
Replacement of Aortic valve
AVR
Aortic regurgitation & aortic stenosis can present with similar signs
What are the signs of Aortic regurgitation, and how can the symptoms be used to differentiate between the two?
Heart failure
Angina
Aortic stenosis also causes syncope episodes so if patient had fainted or whatever, then that would indicate aortic STENOSIS and not regurgitation
How could you differentiate between Aortic regurgitation & aortic stenosis on examination?
Aortic stenosis = systolic murmur
Aortic regurgitation = diastolic murmur (hard to hear)
If severe aortic regurgitation persists for a long time, what effect can it have on the heart?
LV dilation
How would aortography be used to diagnose severe aortic regurgitation?
Imaging would show the entire LV is filled with contrast after one diastolic interval
How does mitral valve stenosis sound on auscultation?
Murmur is usually difficult to hear
(May have to exercise the patient to hear the murmur)
If easily heard then the stenosis is severe
Presystolic accentuation may be present
Because auscultation for mitral valve stenosis is fairly difficult, what other investigative technique is important?
ECHO
ECHO investigation can identify severe mitral stenosis & indicate the need for surgery
How would an ECHO indicate that MVS is severe enough?
Surgery recommended if MVA on ECHO is < 1.5cm2
Which is easier to hear, Mitral stenosis or regurgitation?
Mitral regurgitation easily heard
What are the effects of severe mitral regurgitation on the Cardiovascular system?
Severe MR is associated with LV and LA dilatation, onset of AF and pulmonary hypertension
How would an ECHO indicate severe Mitral regurgitation?
Severe MR on ECHO characterised by systolic blood flow reversal in the pulmonary veins
Severe MR = MVR surgery needed
Heart valve replacement surgery requires surgeons to be cutting up someones heart - meaning its not working (obviously)
What bit of machinery is thus needed for this surgery?
Cardiopulmonary bypass machine
Operated by perfusionists
How is the flow of blood different using a CPB machine?
Non-pulsatile flow
What type of drugs are needed when using CPB?
Systemic anti-coagulants
This creates the risk of coagulopathy
What happens to a patients body temperature when using a CPB machine?
Induced hypothermia
No clue why
What is the time limit on cardiac surgery using a CPB machine?
12 hours max
Maximum cardiac ischaemic time is 6 hours
What is a specific risk associated with open surgery, such as valve replacement surgery?
Air embolism
What are the 2 types of replacement valves, and the advantages/disadvantages of each
Biological valve:
- No warfarin needed, however, it wears out after 15 years
Mechanical valve:
- Warfarin needed, but it lasts much longer > 40 years
Is Valve replacement the only surgical option for treating all these valve problems?
Mitral valve repair is often possible for degenerative Mitral regurgitation
This is preferred to replacement if full competence can be restored
