Chest pain Flashcards
The basic ECG waveform:
- P wave
- QRS complex
- T wave
- P wave: atrial depolarisation (contraction)
- QRS complex: Ventricular depolarisation (contraction)
- T wave: ventricular re-polarisation (relaxation)
ECG calibration spike dimensions:
- 10 mm tall
- 5 mm wide
ECG heart rate measurement:
- Heart rate = 300 / R-R interval
Rhythm:
- What is the rhythm
- Sinus rhythm
- Signs
- Where the action potential started
- Sinus rhythm: action potential starts at the sinus node
- Signs of normal sinus rhythm: P waves upright in Lead II, all P waves should be identical
Isolated systolic hypertension:
- Isolated elevation in systemic pressure alone with normal diastolic pressures
- Common in elderly due to increased stiffness of large elastic vessels (aorta)
White coat hypertension:
- rise in blood pressure while being examined by a physician (fight or flight response)
Primary (essential) hypertension:
- ~95% of cases, no known cause identified
- BP > or = 140/90 mm Hg
Secondary hypertension:
- ~ 5% of cases with a defined underlying cause
- Uncommon but important as may be treatable
Hypertension organ damage: heart & coronary arteries (2)
- Left ventricular hypertrophy (LVH) in response to chronic elevation of after-load (due to high TPR) my cause congestive cardiac failure
- Accelerated coronary atherosclerosis predisposing to ischaemia and infarction
Sign of LVH:
- S wave in V1 or V2 + R wave in V5 or V6 > 35mm
Hypertension organ damage: brain (3)
- Longstanding hypertension can lead to ….
- Atherosclerotic plaques in the internal ….
- Occlusion of small penetrating branches may result in ….
- Longstanding Hypertension can lead to micro-aneurysms that may rupture to cause haemorrhagic stroke
- Atherosclerotic plaques in the internal carotid arteries can cause emboli that result in cerebral infarcts
- Occlusion of small penetrating branches may result in multiple tiny infarcts resulting in lacunae (cavities)
Hypertension organ damage: aorta and peripheral vasculature (3)
- Peripheral vasculature disease
- Abdominal aortic aneurysm “AAA” (>6cm diameter, high risk of rupture and death)
- Aortic dissection
Hypertension organ damage: kidney (2)
- All patients with hypertension should have urinalysis performed
- Nephrosclerosis (scarring), may cause proteinuria and chronic renal failure
Hypertension organ damage: retina
- Damage can be directly viewed here
Secondary hypertension signs: (5)
- Young age of onset
- Abrupt onset
- Signs of underlying pathology
- Sporadic (i.e. no history in first degree relatives)
- Refractory to drug treatment
Causes of secondary hypertension: (5)
- Renal (chronic renal failure, renal artery stenosis)
- Mechanical (coarctation of aorta)
- Endocrine (Cushings syndrome)
- Drugs (e.g. oral contraceptives)
- Pre-eclamptic toxaemia of pregnancy
Renal artery stenosis:
- Activation of renin-angiotensin-aldosterone system results in hypokalaemia
- Suspect in patients with hypertension, hypokalaemia and abdominal bruit
Coarction of the aorta: (4)
- Congenital narrowing of the aorta often distal to origin of left subclavian artery
- BP in arms > legs
- Weak or absent femoral pulse
- Notched appearance of ribs on CXR due to shunting of blood through enlarged arteries
Conn’s syndrome: (3)
- Adrenal tumor (adenoma) excretes excess aldosterone
- Often asymptomatic
- produces hypokalaemia
Cushing’s syndrome: (2)
- Excess glucocorticoid secretion
- “Cushingoid” appearance including moonface, acne, obesity and proximal muscle wasting
Phaeochromocytoma:
- What
- Causes
- Catecholamine secreting tumour (often of the adrenal medulla)
- Episodes of anxiety, sweating, palpitations and hypertension
Pre-eclamptic toxaemia of pregnancy
- Placental ischaemia leads to release of agents causing endothelial dysfunction and vasoconstriction, resulting in hypertension
- Occurs in 7-10% of pregnancies and can cause fits and maternal death
Hyperthyroidism:
- Produces hypertension through an increase in blood volume and cardiac output due to excessive secretion of thyroid hormones
Pathophysiology of primary hypertension: (3)
- An imbalance between CO and TPR
- CO appears raised at first, disease progression causes LVH that compromises diastolic filling and reduces CO
- Reduction in CO causes changes to blood vessels that increases TPR long-term
What causes elevated TPR in primary hypertension? (2)
- Narrowing of small arteries due to hypertrophy of tunica media
- Rarefaction, reduction in no. vessels per unit volume of tissue
Accelerated (malignant) hypertension:
- Definition
- Effects
- KEY
- > or equal to 180/120 mmHg + papilloedema and or retinal haemorrhage
- Pathology: fibrinoid necrosis of the arterioles
- May impair function of the brain, if untreated most die within 6-12 months
- MEDICAL EMERGENCY
Ischaemic heart disease is a group of pathological syndromes due to imbalance of (2)
- Oxygen supply: coronary blood flow and oxygen extraction/saturation
- Oxygen demands: cardiac contractility/rate and ventricular wall tension (systolic/diastolic)
Coronary circulation:
- Definition
- Arteries supplying the myocardium with oxygenated blood during diastole
Coronary artery dominance (3)
- 70% of individuals have the posterior descending branch originating from the right coronary artery
- 20% are co-dominant
- 10% posterior descending branch originates drom the circumflex artery (LEFT BRANCH)
Atherosclerosis definition:
- Disease of the arterial intima featuring a slow accumulation of lipid debris (30-40 year) associated with inflammatory reaction (atheroma), causing obstruction and possible ruptures
Arteriosclerosis:
- Blanket term for all conditions where there is a thickening of arterial walls and loss of elasticity
- Arteriolosclerosis, medial calcific sclerosis, ATHEROSCLEROSIS
Ischaemic heart disease (IHD):
- Definition
- Effects
- Clinical manifestation of coronary arterial narrowing due to atherosclerosis
- Comprises of stable angina and acute coronary syndrome (unstable angina, acute MI, acute HF and sudden death)
Ischaemia:
- Reduced oxygen
- Reduced nutrients
- Impaired wash out of metabolic waste
Ischaemia causing stable angina:
- Location
- Duration
- Cause
- Obstruction
- Relief
- Pain over sternum, radiating to left shoulder/arm and jaw
- Seconds to hours
- Sharp/stabbing pain
- Triggered by exertion, cold weather, heavy meals
- Obstruction >60%
- Relieved by rest
Ischaemia causing unstable angina:
- Pain characteristics
- Relief??/
- Signs
- Similar to stable angina in terms of pain characteristics
- Not relieved by rest
- No cardiac biomarkers and ECG appears normal (possible ST depression)
Ischaemia causing myocardial infarction: (2)
- Ischaemia causes necrosis of the myocardium
- Release of cardiac biomarkers
ECG in ischaemia caused MI: (4)
- Normal
- ST segment depression
- T wave inversion: «risk of acute total occlusion of main artery
- ST segment elevation: acute occlusion of one of the three main coronary arteries
Percutaneous coronary intervention: (4)
- A catheter is inserted into either the groin or the arm
- Using a fluoroscopy, the catheter is threaded to the plaque build up in the coronary arteries
- It places a stent using a balloon head to compress the plaque and restore appropriate artery width
- Balloon head and catheter removed
Coronary artery bypass graft: (2)
- A surgical procedure where a blood vessel is taken from an arm, leg etc and then grafted above and below a blockage of the coronary artery
- This diverts the blood flow, allowing a proper supply of blood to the myocardium
Complications following MI:
- 80% of survivors experience some complications after an MI
SHIT LOAD OF COMPLICATIONS
Modifiable risk factors for Cardiovascular Disease (9)
- S
- P D
- H
- H
- I P A
- O
-D
- S
- E A C
- Smoking
- Poor diet
- Hypercholesterolaemia
- Hypertension
- Insufficient physical activity
- Obesity
- Diabetes
- Stress
- Excess alcohol consumption
Troponin as a biomarker for myocardial infarction:
- Troponin is detected in the blood after myocardial injury
- Specific to the heart - but not to ischaemia, so can not be used to diagnose MI on its own
diagnostic criteria for MI requires;
- KEY REQUIREMENT
+ one of :
- I
- ST
- Q
- loss of ….
- Identification of inter…..
- rise or fall in cardiac biomarker value (preferably troponin) with at least one value above 99th percentile of RR
and one of - Ischaemia symptoms
- ST changes
- Pathological Q waves
- Imaging evidence of viable myocardium loss
- Identification of intercoronary thrombus by angiography
Potassium and the heart: hyperkalaemia
- Effects
- Increases cardiac excitation, increases risk of cardiac arrhythmia and heart block
Potassium and the heart: hyperkalaemia
- ECG signs (2)
- Tented T waves
- Reduced P wave amplitude
Potassium and the heart: hyperkalaemia
- causes
- Acute kidney injury/ chronic kidney disease
- Drugs (ACE-inhibitors, ARBs, NSAIDs)
- Mineralocorticoid deficiency (Addison disease)
Potassium and the heart: hypokalaemia
- Effects
- Increases the gradient across cardiac cell membrane, increasing AP and therefore reducing cardiac excitability
- May cause arrhythmias such as atrial fibrillation
Potassium and the heart: hypokalaemia
- ECG changes (3)
- Reduced T waves
- ST depression
- Prolonged PR interval