Cardiovascular Flashcards
(150 cards)
MI (NSTEMI) Definition
- Acute ischaemic event causing myocyte necrosis
- Initial ECG may show ischaemic changes such as ST depressions, T-wave inversions or transient ST elevations – may also be normal or show non-specific changes
how common is an MI (NSTEMI)
• CVD is the number one cause of death worldwide
affects mainly men
causes of an MI (NSTEMI)
• Result of an acute imbalance between myocardial oxygen demand and supply, most commonly due to a reduction in myocardial perfusion
• Several different sequences of events that may lead to an NSTEMI:
- Plaque rupture with superimposed non-occlusive thrombus or embolic events leading to coronary vascular obstruction MOST COMMON CAUSE
- Dynamic obstruction, such as in vasospasm
- Progressive luminal narrowing (i.e. chronic arterial narrowing from restenosis)
- Inflammatory mechanisms i.e. vasculitis
- Extrinsic factors leading to poor coronary perfusion (such as hypotension, hypovolaemia or hypoxia)
Risk factors for an MI (NSTEMI)
- Atherosclerosis
- Diabetes
- Smoking
- Dyslipidaemia
- Age >65yrs
- HBP
- Cocaine use
- Depression
Symptoms/ signs for an MI (NSTEMI)
- Presence of risk factors
- Chest pain tightness, heaviness, aching, burning, pressure or squeezing – pain is most often retrosternal and can often radiate to the left arm, lower jaw, neck etc
- Diaphoresis – sweating to an unusual degree
- Abdo pain
- HBP
- N&V and SOB
- Physical exertion
- Diabetics may not have chest pain
DDx for MI (NSTEMI)
- STEMI
- Aortic dissection
- PE
- Peptic ulcer disease
- Acute pericarditis
- Oesophageal spasm
- Costochrondritis
Investigation for MI (NSTEMI)
• 1st LINE:
- ECG: non-specific ST-T wave changes or ischaemic changes
- TRIAL OF SUBLINGUAL GLYCERYL TRINITRATE: ongoing pain
- CARDIAC TROPONIN: test is more specific than CK-MB or myoglobin and is the best marker for msk injury and small MI - >99th percentile of normal
- CK: >99th percentile of normal
- CK-MB: - >99th percentile of normal
- FBCs, U&E’s, Serum Creatinine, LFTs, blood glucose
- CXR: may show pulmonary oedema
Management for MI (NSTEMI)
• 1st LINE:
- MONA – morphine, oxygen (only if <94% sats), nitrates (GTN), aspirin
- Aspirin: orally
- If aspirin-intolerant clopidogrel
- Give oxygen if O2 sats below 90%
- PLUS: beta-blocker, calcium-channel blocker, glyceryl trinitrate
prognosis and complications for MI (NSTEMI)
- CVD responsible for about 30% of UK deaths
- Cardiac arrhythmias, depression, CHF, cardiogenic shock
definition of MI (STEMI)
- Myocardial cell death that occurs because of a prolonged mismatch between perfusion and demand
- Usually caused by occlusion in the coronary arteries
- ST-elevation MI is suspected when a patient presents with persistnet ST-segment elevation in 2 or more anatomically contiguous ECG leads in the context of a consistent clinical history
How common is MI (STEMI)
- CVD responsible for about 30% of UK deaths
- MIs are 3 times more likely in men than women
causes of MI (STEMI)
- Atherosclerotic plaques form gradually over years
- They begin with the accumulation of low-density lipoprotein cholesterol and saturated fat in the intima (inner layer) of blood vessels
- Followed by the adhesion of leukocytes t the endothelium, then diapedesis and entry into intima where they accumulate lipids and become foam cells – rich source of proinflammaotry mediators FATTY STREAK
- Subsequent evolution involves migration of smooth muscle cells from the media, and their proliferation and deposition of extracellular matrix including proteoglycans, interstitial collagen and elastin fibres – some of the smooth muscle cells in advanced plaques exhibit apoptosis – plaques often develop calcification spots as they evolve eventually causes arterial occlusion and stenosis
- STEMI typically occurs after abrupt and catastrophic disruption of a cholesterol-laden plaque - this results in exposure of substances that promote platelet activation and aggregation, thrombin generation, and thrombus formation, causing interruption of blood flow
- If the occlusion is severe and persistent, myocardial cell necrosis follows
- On interruption of blood flow in the coronary artery, the zone of myocardium supplied by that vessel immediately loses its ability to shorten and perform contractile work
- Early hyperkinesis of the non-infarcted zones occurs, probably as a result of acute compensatory mechanisms including increased sympathetic activity and Frank-Starling mechanism
- As necrotic myocytes slip past each other, the infarction zone thins and elongates, especially in anterior infarction, leading to infarction expansion
risk factors for MI (STEMI)
- Hypertension
- Smoking
- Diabetes
- Obesity
- Metabolic syndrome
- Physical inactivity
- Dyslipidaemia
- Renal insufficiency
- Established coronary artery disease
- Fx of premature coronary artery disease
- Cocaine use
- Male sex
- Advanced age
symptoms/signs for MI (STEMI)
- Chest pain - diabetics may not have chest pain
- Dyspnoea
- Pallor
- Diaphoresis – common feature associated with MI due to high sympathetic output
- Nausea
- Vomiting
- Dizziness
- Weakness
- Tachycardia
- Additional heart sounds audible S3 or S4 on cardiac exam indicates poor cardiac muscle compliance of the infarcted muscle
DDx for MI (STEMI)
- Unstable angina
- NSTEMI
- Aortic dissection
- PE
- Pneumothorax
- Pneumonia
- Pericarditis
- Myocarditis
- GORD
Investigations for MI (STEMI)
• 1ST LINE:
- ECG: if ECG shows ST-segment elevation, the patient should be urgently assessed for reperfusion therapy
- CARDIAC BIOMARKERS: elevated troponin
- GLUCOSE: hyperglycaemia is common in the setting of acute MI, with or without a history of diabetes – normal or elevated levels
- U&E’s: determines if any disturbances that may need management are present – may be abnormal
- SERUM LIPIDS: cholesterol levels may be lowered by high catecholamine levels produced by the MI in its early phases – need ot be repeated in 30-60 days – normal or elevated levels
- CXR: widened mediastinum suggests aortic dissection, pulmonary oedema indicates impaired cardiac function
- CORONARY ANGIOGRAM: presence of thrombus with occlusion of the artery
Management for MI (STEMI)
• 1ST LINE: - ASPIRIN: orally o Give oxygen if O2 sats below 90% o If ongoing chest pain give morphine • If unstable revascularisation (PCI) or coronary artery bypass graft (CABG)
Prognosis or complications for MI (STEMI)
Prognosis - about 15% who have an acute MI will die from it
complications - sinus bradycardia, complete heart block with anterior MI, recurrent chest pain
Acute Coronary Syndrome definition
- Refers to a spectrum of acute MI or infarction
- Divivded into three clinical categories according to the presence or absence of STEMI, NSTEMI and unstable angina
- Syndrome which describes decreased blood fow in the coronary arteries such that part of the heart muscle is unable to function properly or dies
- Depending on the tests this can go from: ECG ST-elevation or no ST-elevation, unstable angina from cardiac markers if pos, neg it is MI and either NSTEMI or STEMI
Angina (Stable) definition
- SHID and low-risk unstable angina are most commonly caused by atheromatous plaques in the coronary arteries that obstruct blood flow
- Anginal symptoms are a clinical manifestation of ischaemia
- Key contributory factors to progression of atheromatous disease include smoking, hypertension, hyperlipidaemia, diabetes and obesity
how common is Angina (Stable)
prevalence is unclear
higher in males than females
causes of Angina (Stable)
- Atheromatous plaque leading to obstruction of coronary blood flow is the most common cause
- Damage to the aterial wall produces an inflammatory response and the development of atheromatous plaques
- Exposure of the arterial endothelium to low-density lipoproteins results in the expression of adhesion molecules that allow leukocytes to stick to the arterial wall
- Upon entry into the artery wall, blood monocytes begin to scavenge lipids and become foam cells
- Macrophage foam cells release additional cytokines and effector molecules that stimulate smooth muscle migration from the arterial media into the intima, as well as smooth muscle cell proliferation
- In this process, the initial fatty deposition of lipoprotein in the arterial intima develops ito atherosclerotic plaques
- Ischaemic symptoms may result from obstruction of blood flow due to atherosclerotic plaques or when a clot or vasospasm is superimposed on less severe plaques
risk factors for Angina (Stable)
- Advancing age
- Smoking
- Hypertension
- Elevated LDL cholesterol
- Isolated low HDL cholesterol
- Diabetes
- Inactivity
- Obesity
- Male
symptoms/signs of Angina (Stable)
- Presence of risk factors
- Typical angina symptoms – chest pressure or squeezing lasting several minutes, provoked by exercise or emotional stress and relieved by res or GTN
- Atypical angina symtpoms – chest discomfort with only 2 characteristics of typical angina
- Features of low-risk unstable angina include pain from exertion lasting less than 20 minutes, pain not rapidly increasing and normal/unchanged ECG