Myocardial Ischaemia (pathology) Flashcards
What is the definition of Mycordial ischaemia?
oxygen supply and demand mismatch due to reduction in coronary artery blood flow to myocardium due to obstructive coronary atheroma (obstructive plaque >70% lumen)
What causes myocardial ischaemia (5)?
Atherosclerosis Embolism Coronary thrombosis Aortic dissection Arteritides (inflammation of arteries)
What are arteritides?
Inflammation of arteries:
(Giant cell arteritis, Kawasakis disease, Syphilis) —> can affect ascending aorta
Clinically looks like angina
What are the non-modifiable risk factors of myocardial ischaemia (5)?
Male sex Age Caucasian Post-menopausal female Existing peripheral vascular disease
What are the modifiable risk factors of myocardial ischaemia (6)?
Smoking Lifestyle (diet exercise) Diabetes mellitus Hypertension Hyperlipidaemia Previous CAD
What are the symptoms of myocardial ischaemia?
Stable angina: - retrosternal pain - tightness, pressure, heaviness - radiation to neck, jaw, left arm - aggravated by exertion, emotional stress, heavy meal, cold weather - relieved by GTN or rest Other symptoms on exertion (no pain) - SOB - excessive fatigue - near syncope - in elderly
What are the signs of myocardial ischaemia (6)?
Tar stained fingers (smoker) Obesity Xanthelasma & corneal Arcus Arterial bruits of AAA Absent/reduced peripheral pulses Diabetic or hypertensive retinopathy
What are the signs of conditions aggravating myocardial ischaemia (5)?
Pallor of anaemia
Tachycardia, tremor
Ejection systolic murmur (aortic stenosis)
Pansystolic murmur (mitral regurgitation)
Basal crackles, raised JVP, peripheral oedema (heart failure)
What are the non-invasive diagnosis/investigations of myocardial ischaemia?
Bloods:
- FBC, lipids, fasting glucose, LFT, thyroid
CXR:
- show pulmonary oedema, rule out other causes of chest pain
12 lead ECG:
- normal >50% cases
- prior MI = pathological Q waves
- left ventricular hypertrophy = ST depression, high voltage
ETT:
- ECG at rest/on exertion
Myocardial perfusion imaging:
- radionuclide imagining at rest/under exercise or pharma stress (normal myocardium takes up tracer)
CT coronary angiography: GOLD standard
Echo stress ultrasound
What are the invasive diagnosis/investigations of myocardial ischaemia?
Cardiac catheterisation/ coronary angiography:
- local anaesthetic - cannula in femoral/radial artery - catheter in coronary artery + IV contrast = x-ray visualisation
What is the general treatment/ management for myocardial ischaemia?
Address the risk factors
What is the medical treatment/ management to reduce O2 demand for myocardial ischaemia, in order to reduce progression?
Reduce progression:
- statins (atorvastatin, simvastatin) - aspirin - 75mg-150mg/(clopidogrel, ricagrelor, prasugrel) - if allergic to aspirin - ACEi (-pril) or ARBs (-sartan)
What is the medical treatment/ management to reduce O2 demand for myocardial ischaemia, in order to relieve symptoms?
Symptom relief:
- Nitrates (GTN) - vasodilators which reduce preload & afterload - beta blockers (Bisoprolol, atenolol) - reduce HR & contractility - Ca+ channel blocker: - central action (Diltiazem, Verapamil) - lower HR and preload - peripheral acting (Amlodipine, felodipine) - vasodilation, lower BP & afterload - IF channel blockers (ivabradine) - reduce HR - K channel activators (nicorandil) - INa blockers - Ranolazine
What is the surgical treatment/management options to increase O2 supply for myocardial ischaemia?
PCI - stenting
CABG
What is follow up of PCI stenting to increase O2 supply
PCI - stenting:
- Aspirin & clopidogrel 6months post op - no prognostic benefit (only symptom management) - continue to reduce progression meds
What is process of CABG to increase O2 supply? What are requirements?
CABG
- multivessel disease - left main stem disease - disease not amendable to PCI - may confer prognostic benefit? - improves QOL - reverse saphenous vein - free graft - LIMA - fixed arterial graft - radial arteries if varicose veins - (LIMA>saphenous vein) - especially vein graft - continue reduce progression meds
What is stenotomy? what do you need to watch out for?
Operation where incision made along sternum and chest ‘cracked open’
E.g. Cardiopulmonary bypasses
Watch out for:
- tamponade - haemorrhage - wire infection - sternal dehiscence - malunion
What is tamponade? What are the signs?
Extra fluid building up around the heart
Tamponade signs:
- ↑ CVP, HR
- ↓ BP
- oliguria (low urine output)
- ↑↑ O2 demand
- metabolic acidosis
- > re-open chest
What is a stenosis?
Narrowed vessel (often due to atherosclerosis)
Where can the stenosis be relieved (4)?
Origin of coronary arteries
Coronary orifices at aortic root - OSTIAL STENOSIS
Downstream within coronary arteries
Discrete single point = stenting