Pre-Operative Aortic Stenosis Flashcards
What is the pathophysiology of aortic stenosis?
Normal
- When the heart contracts the aortic valve opens and blood is pumped into the aorta
- When the heart relaxes, the aortic valve closes
In Aortic Stenosis
- A narrowed aortic valve limits the amount of blood ejected from the ventricle into the aorta
- Increases afterload by increasing pressure
- Increases contractility to overcome the outflow resistance
- This results in ventricular hypertrophy followed by degeneration of cardiac myocytes
What does an Echo assess?
- Valve surface
- Ventricular dilation
- Ejection fraction
What is the anaesthetic issue with aortic stenosis?
- Fixed COP → cannot respond to decreased afterload which may happen with anaesthesia / blood loss
- Arrythmia
- Ventilation: positive ventilation pressure → ++ VR
What is the clinical picture of aortic stenosis?
- Symptoms:
- Neuro: weakness, fatigue, syncope
- CVS: Anginal pain, palpitations
- Resp: Paroxysmal nocturnal dyspnoea & Orthopnoea
- Sings:
- Ejection Systolic murmur (right 2nd intercostal space on right sternal border)
- Paradoxical splitting of S2
- Pulsus alternans
- Narrow pulse pressure
What are the Complications of aortic stenosis?
- HTN → Left Ventricular Hypertrophy → Congestion Heart Failure → Myocardial Infarction
- Arrythmia: VT, VF
- Increased risk of IE, Blood clots
- Sudden cardiac death
What are the Investigations for aortic stenosis?
- ECG
- Echocardiography
- Cardiac enzymes
- Cardiac catheterization
- Exercise stress test
How to determine ECG axis
- Look at leads I and aVF.
- Determine the quadrant they are in (positive or negative).
What is the Management of Aortic stenosis
Lifestyle modifications:
- Avoid strenuous activity may cause syncope
- Avoid dehydration and hypotension.
- Treat any underlying medical conditions, such as hypertension or diabetes.
Medical management:
- Ace inhibitors
- Beta blockers
- Diuretics
Surgical management:
- Aortic valve replacement (AVR) is the definitive treatment for severe symptomatic AS.
- Transcatheter aortic valve replacement (TAVR) is an alternative to AVR for high-risk patients.
- Balloon aortic valvuloplasty (BAV) can be used as a palliative treatment in patients who are not candidates for AVR or TAVR.
Interpret this ECG
ECG suggest Left Vetricular Hypertrophy probably due to the presence of AS as evident by:
- Large R-waves in left sided leads (V5, V6)
- deep S-waves in right sided leads (V1,V2)
- T wave inversion, ST changes
- P mitral
If you find out a patient has suspected aortic stenosis from clinical examination & ECG and is due an elective procedure (TURBT), what should you do?
- I will inform: consultant, anaesthetis, theatre
- Cancel the operation, arrange for medical optimisation and reschedule
- Explain to patient - Duty of candour
- Why was this not picked up earlier: discuss, audit, teaching incident form
Which surgery does the patient need to have first TURBT or Valve surgery in a patient with new diagnosis of aortic stenosis?
This will depend on the severity of aortic stenosis:
Normal aortic valve surface area is 2.5-3.5 cm2
< 1cm2 = severe stenosis
- Balance risk of spread to risk of delaying AS, discuss with patient.
- if you’ll do TURBT, antibiotics prohylactic against IE
What if the patient is on Thiazide diuretics ?
Must be stopped on the morning of surgery to avoid dehydration, hypotension and hypokalemia
Do the patient need to be prescribed antibiotic prophylaxis against infective endocarditis?
Is not recommended
- dental procedures
- gastrointestinal tract
- Genitourinary tract
- respiratory tract
- only be considered in patients at risk of IE if the operative site is suspected to be infected, and therefore, significant bacteremia is to be induced. This applies mainly to microorganisms that have the potential to cause bacterial endocarditis.
