Stroke, atherosclerosis, oedema, arrhythmias and valve disease Flashcards
Define red and white thrombi (origin and composition)
- Red thrombus: contains mostly RBCs and fibrin. Venous origin, caused by stasis or hypercoagulability
- White thrombus: contains lipids/platelets and fibrin. Arterial origin, broken off atheroma plaque
What are the three components of Virchow’s triad?
- Change in blood flow (ie stasis)
- change in blood components (ie hypercoagulability)
- change in blood vessel (ie endothelial damage)
What investigations should be done to diagnose pulmonary embolism?
- If Wells probability score low - do a blood test for D-Dimer
- If Wells probability score high - do CT Pulmonary Angiogram
If D-Dimer positive - do CT Pulmonary Angiogram
What are the two main types of Venous Thromboembolism (VTE)?
Deep vein thrombosis (DVT) and Pulmonary Embolism (PE)
Define embolism
Material in the circulation which dislodges from original place and moves to another area of the body. Can be a blood clot but also air, lipids etc
What are two causes for stasis (blood pooling, change in blood flow in Virchow’s triangle)?
Long flights, immobility/bedbound status
What can cause hypercoagulability?
Inherited or acquired (Pregnancy, surgery, cancer)
What can cause endothelial damage?
Endothelial dysfunction (caused by smoking, hypertension, hypercholesterolaemia) Endothelial injury (IV catheters, trauma, surgery)
What are common signs of DVT?
Unilateral swelling, discomfort, redness, may be silent
Define claudication
Pain in leg(s) due to ischaemia caused by occluded artery supplying the leg.
What is a common complication of DVT and what are its implications?
Post-thrombotic syndrome, can affect up to half the patients who have had DVT in previous months.
Causes chronic pain, swelling, redness, ulcers and damage to valves in the veins
How is DVT diagnosed?
- Clinical assessment and Wells score
- Wells test result low –> blood test for D-Dimer
- Wells test high/D-Dimer positive –> compression ultrasound or doppler ultrasound
What is the Wells probability test?
It’s a measure to calculate the risk of thrombosis based on risk factors
What is a D-Dimer?
It’s a byproduct of the breakdown of cross-linked fibrin following fibrinolysis
What are the diagnostic advantages and disadvantages of D-Dimer blood testing?
It’s very sensitive to D-Dimer presence in the blood, so useful to rule out thrombosis.
It’s not very specific, there are other causes for raised D-Dimer levels so a positive result may not be due to thrombosis
What are the four main types of valve disease?
Mitral stenosis,
Mitral regurgitation,
Aortic stenosis
Aortic regurgitation
Which heart valves are more likely to have congenital abnormalities?
Right heart valves - tricuspid and pulmonary
What are the main causes of mitral stenosis?
Rheumatic heart disease Systemic diseases (SLE, RA) Congenital defect
What are the main symptoms of mitral stenosis?
Shortness of breath (exertion) Shortness of breath (pulmonary oedema) Haemoptysis Hoarse voice (compressed recurrent laryngeal nerve) Infective Endocarditis
What are the main signs of mitral stenosis?
Mitral facies RV hypertrophy Pulmonary oedema Pulmonary hypertension Raised JVP (a wave) Tapping apex beat Diastolic thrill
Which valve diseases have a long asymptomatic phase?
Aortic stenosis and aortic regurgitation
What investigations can be done to diagnose mitral stenosis?
Cardiac catheter CXR ECG Echocardiogram Cardiac magnetic resonance
What are the steps in diagnosing Pulmonary Embolism?
Wells score low - D-Dimer
D-Dimer positive - CT Pulmonary Angiogram, V/Q scan
Wells score high - CT Pulmonary Angiogram, V/Q scan
What are the common signs and symptoms of PE?
Pleuritic chest pain, SOB, tachycardia, haemoptysis, pleural rub
If PE severe: severe SOB, central cyanosis, low BP, raised JVP, sudden death
What are the main treatment options for Vascular Thromboembolism (VTE)?
Anticoagulants (fractionated or LMW heparin; warfarin, DOACs)
Thrombolysis (eg alteplase, in severe cases)
What measures can be taken to prevent VTE occurring?
Early mobilisation, stockings, mechanical or pharmaceutical thromboprophylaxis
What are the main aims of VTE treatment?
Prevent recurrence, prevent clot extension and further embolisation
What is a possible long term complication of PE?
Pulmonary hypertension
How can PE lead to pulmonary infarction, and how likely is it?
Infarction rare due to collateral circulation in lungs.
It occurs through leaking fluid into alveoli due to increased pressure in bronchial circulation
What are three important considerations when VTE has been diagnosed?
- Clear cause of VTE (eg recent surgery, long flight)
- Signs or symptoms indicating underlying malignancy
- Chance of recurrence
What are the common causes of abdominal aortic aneurysms?
- Atherosclerosic disease
- Connective tissue diseases (eg Marfan’s Syndrome)
- Infection
What are common risk factors for aneurysms?
Same ones as for atheromatous plaques:
Hypertension, age, smoking, diabetes, family history, high cholesterol, males
When should surgical repair of aneurysm be considered?
If aneurysm is enlarged to >5.5cm
What are the most common presentations of aneurysm?
Nothing, it’s normally picked up incidentally (especially through ultrasounds for gallstones). May present as back pain
What is the purpose of screening for aneurysms?
It helps to identify aneurysms before they rupture and monitor ones which are not large enough to call for repair
If an abdominal aortic aneurysm measuring 3-4.5cm is found, what is the course of action?
Patient should be discharged an be invited back for yearly ultrasound scans to monitor the aneurysm
If an abdominal aortic aneurysm measuring 4.5-5.5cm is found, what is the course of action?
Patient should be discharged and be invited back every 3 months for a surveillance ultrasound scan
What are common presentations of a ruptured abdominal aortic aneurysm?
Shock
back/side/abdominal pain
haematodynamic instability
hypoperfusion
What are some less common presentations of a ruptured abdominal aortic aneurysm?
Distal embolisation (toes, kidneys, colon) compression of duodenum compression of ureter aortocaval fistula aortoenteric fistula
What are the surgical repair options for a ruptured abdominal aortic aneurysm?
Open repair or endovascular repair (EVAR)
What imaging techniques are used for assessing abdominal aortic aneurysm size, and what are their pros and cons?
Ultrasound:
Pros: cheap, accessible, tolerated by patient
Cons: operator dependent, no anatomic detail
CTA/MRA scan:
Pros: very quick (30s), not operator dependent, very clear anatomic image
Cons: radiation and contrast
What factors should be considered when assessing surgical repair for abdominal aortic aneurysm?
Patient fitness (lung, heart, kidney function)
Patient wishes
Aneurysm size
Anatomy (determines which type of surgery is suitable)
What are three main treatment options for abdominal aortic aneurysms?
Conservative treatment
Endovascular repair (EVAR)
Open repair
List some of the complications of open repair for abdominal aortic aneurysms
Pain/scarring/bleeding/dehiscence/wound infection
Damage to structures adjacent to aorta (nerves, bowel, veins, ureter)
distal embolisations and ischaemia, graft infection
colon ischaemia (redundant inferior mesenteric artery), kidney damage,
CVA/MI/PE
List some of the complications of EVAR for abdominal aortic aneurysms
Pain/scar/bleeding/wound infection Endoleak Damage to endothelium (femoral dissection, pseudoaneurysm) distal embolisations, graft infection, CVA/MI/PE
What is an endoleak?
It’s blood leakage in the area of the aneurysm that has been grafted
What investigation should be done to assess whether an aneurysm rupture should be repaired with open repair or EVAR?
CT scan to assess anatomic suitability for EVAR
When is an endarterectomy performed?
When a patient has/has had TIA/stroke symptoms and the relevant carotid artery is >70% but <99% occluded
What course of action should be taken if one carotid artery is completely occluded?
Best medical care (BMC), operation will not benefit patient since other arteries are still supplying Circle of Willis
What investigations should be done when a patient presents with a stroke?
CT scan - rule out a haemorrhagic stroke
Doppler ultrasound - to assess degree of carotid stenosis
What is the main management aim of TIA/stroke, and what are the common management steps?
Management to reduce risk factors:
- smoking cessation
- antiplatelet (2x for first 3 months)
- statin
- blood pressure medication
- diabetic control
What investigations should be carried out to diagnose stroke/TIA?
History examination bloods (FBC, lipids) ECG (24hr) CT/MRI carotid ultrasound scans
What are the possible complications of an endarterectomy?
Bleeding, scarring, pain, infection
anaesthetic complications
damage to recurrent laryngeal nerve
perioperative stroke (thrombosis, hypoperfusion)
What factors can influence the management decision for stroke? (ie endarterectomy or best medical treatment)?
Patient wishes Anatomic suitability Degree of carotid stenosis Time since stroke/TIA Females
When is the most beneficial time to carry out endarterectomy to reduce further events?
First 2 weeks post event (faster is better in women)
When would carotid stenting be considered in the prevention of stroke?
If patient is not anatomically suitable for endarterectomy (eg scarring or occlusion is further up the internal carotid artery)
What treatment will be offered to a symptomatic patient with 60% carotid stenosis, and to one with 75% carotid stenosis?
60% - best medical treatment only
75% - best medical treatment + endarterectomy (or stenting if anatomically unsuitable for endarterectomy)
What are the four main types of ischaemic stroke?
Total Anterior Circulation Stroke (TACS)
Partial Anterior Circulation Stroke (PACS)
Lacunar Stroke (LACS)
Posterior Circulation Stroke (POCS)
What is POCS most likely to present with?
visual disturbance (Homonymous hemianopia) breathing problems tinnitus Horner's syndrome loss of function/sensation coma dizzyness balance problems
What is TACS most likely to present with?
Symptoms include face/arm/leg weakness and loss of sensation, speech disturbance, loss of vision
What is PACS most likely to present with?
Combination of 2/3 of the symptoms seen in TACS. Restricted hemiparesis/loss of sensation only, or speech/motor function disturbance only
What is LACS most likely to present with?
Depends on the location.
Sensory only/motor only/sensorymotor/ataxic hemiparesis
What are the two main presentations of stroke and their prevalence?
Ischaemic stroke (85%) Hemorrhagic stroke (15%)
Which type of stroke may go unnoticed and undiagnosed?
LACS
List some of the risk factors for stroke
Atrial Fibrillation Smoking Hypertension Diabetes Previous stroke/MI Hypertension Hypercholesterolaemia Race Family history Age Gender
What are the 5 main presenting characteristics of a stroke?
Loss of function Loss of sensation Loss of vision Loss of balance Loss of speech
What is the main cardiovascular cause for cardioembolic stroke?
Atrial Fibrillation
What is the main cardiovascular cause for haemorrhagic stroke?
Hypertension
What are the benefits of stroke units?
Expertise
Specialised care
Early mobilisation
Attention to improving functions eg swallowing, speech and language, rehabilitation
What is the benefit of informing A&E of stroke from ambulance?
Reducing time it takes to get patient into hospital, to CT and thrombolysed
What imaging investigation should be done when a patient presents with a stroke?
CT to rule out haemorrhage. If ischaemic, thrombolyse (tPA)
Why is it important to improve swallowing function in stroke patients?
To avoid choking or aspiration pneumonia
What type of stroke shows up best on CT scan?
Haemorrhagic stroke
What type of stroke shows up best on MRI scan?
Ischaemic stroke
What is the main complication of thrombolysis?
Bleeding
What seems to be the most effective way to treat a stroke in an emergency?
Thrombolysis + thrombectomy (clot retrieval) if ischaemic stroke
What are the contraindications for thrombolysis?
Age (>80)
Recent bleeding
severe hypertension
When should hemicraniectomy be considered?
- Patient is <60yo
- ischaemic MCA occlusion with cerebral oedema
- <48hrs from onset
What common antiplatelet drugs are used in secondary prevention of stroke?
Aspirin
Clopidogrel
Dipyridamole
What main treatment should be used for stroke prevention in patients with AF?
Anticoagulants
- warfarin
- DOACs (apixaban, rivaroxaban)
What is the main cause of atherosclerosis?
Hypercholesterolaemia
What is atherosclerosis?
Formation of atheromatous plaques in areas of damaged endothelium
What are atheromatous plaques made up of?
Inner mass of dead macrophages, cholesterol, lipids, calcium
Outer cap made up of collagen and fibrous tissue (stimulated by PDGF)
What does complicated atheroma mean?
It’s a rupture of an atheromatous plaque, which causes inflammation/thrombosis
What are the two types of supraventricular tachycardia?
- AV node re-entral tachycardia (extra conduction in atrial tissue)
- AV re-entral tachycardia (extra conduction from atrium to ventricle)
What characterises first degree heart block?
Slow conduction from sinoatrial node - long PR interval
What characterises second degree heart block?
Mobitz 1 - increasing delay in PR segment until one P wave doesn’t conduct signal to ventricle
Mobits 2 - no pattern, random P waves do not conduct signal to ventricle (no QRS)
What characterises third degree heart block?
P waves have no association with the QRS waves, occur indepentently of eachother
What is the difference between atrial flutter and atrial fibrillation on an ECG?
Atrial flutter - sawtooth
Atrial fibrillation - no P wave
What does Wolff-Parkinson-White Syndrome look like on an ECG?
Delta wave (slurred upstroke QRS, wide at the bottom and narrowing at the top)
How to tell supraventricular and ventricular tachycardia apart on an ECG?
Supraventricular tachycardia - narrow QRS
Ventricular tachycardia - broad QRS
Define AV nodal re-rentrant and AV re-entrant supraventricular tachycardia
- AV nodal re-rentrant supraventricular tachycardia: conduction signal goes round in circles around the AV node
- AV re-entrant supraventricular tachycardia: conduction signal sent to ventricles but moves back to the atria through accessory conduction circuit
What are supraventricular ectopic beats?
Beats which come in earlier than they should
Define Torsades de Pointes
Polymorphic ventricular tachycardia
What are the main aims of atrial fibrillation treatment?
Heart rate control (beta blockers, rate limiting CCBs) Rhythm control (drugs, cardioversion, RFA)
When should an internal defibrillator be inserted?
If VF/VT not secondary to reversible cause
If VT continuous and causing syncope or significantly reducing QoL
If VT and LV failure
When should a pacemaker be inserted?
If alternating LBBB and RBBB
If severe or at risk of severe bradycardia
If second or third degree heart block
What investigations should be carried out to diagnose AF?
24hr ECG blood test (to exclude hyperthyroidism and electrolyte abnormality)
Which valve diseases can have a long asymptomatic period?
Aortic stenosis and aortic regurgitation
How do aortic stenosis and regurgitation affect the pulse on examination?
stenosis - rising pulse
regurgitation - collapsing pulse
What are common causes of mitral stenosis?
Rheumatic heart disease
congenital
systemic diseases (SLE, RA)
What are common symptoms of mitral stenosis?
Haemoptysis
SoB
Pulmonary oedema
Systemic emboli (eg stroke)
What are useful investigations for diagnosing mitral stenosis?
Echocardiogram
Cardiac catheterisation (ie angiography)
Cardiac MRI
to a lesser extent: ECG, CXR
What medical treatments should be used for mitral stenosis?
Anticoagulants for AF
Diuretics
What are common acute and chronic symptoms of mitral regurgitation?
acute - cardiogenic shock, severe SoB
chronic - fatigue, SoB on exertion, PND
What are the main investigations carried out for mitral regurgitation?
Echocardiogram (transthoracic/transesophageal)
cardiac MRI
CXR
ECG
What are the medical treatment options for acute and chronic mitral regurgitation?
acute - medical emergency: dobutamine (for cardiogenic shock); sodium nitroprusside (vasodilator), keep patient alive until they can go to surgery
chronic - nothing proven effective
What are the medical treatment options for acute and chronic aortic regurgitation?
acute - medical emergency: dobutamine (for cardiogenic shock); sodium nitroprusside (vasodilator), keep patient alive until they can go to surgery
chronic - vasodilators
What are the medical treatment options for aortic stenosis?
None unless pt develops heart failure
What are the common symptoms of aortic stenosis?
Chest pain
Blackouts
SoB
Name two conditions which can lead to VT/VF
Brugada syndrome
long-QT syndrome
What treatment is most successful in stopping supraventricular tachycardia (nodal re-entral or re-entral)?
Radiofrequency Ablation
What are two potential causes for long QT syndrome?
genetic
acquired (eg drugs)
What is the definition of congestion?
Excess blood in systemic vessels
What is the definition of oedema?
Excess fluid in interstitial space
What are the effects of congestive heart failure?
Left heart failure: pulmonary oedema
Right heart failure: central venous congestion + portal venous congestion
What are the consequences of central venous congestion?
raised JVP
hepatomegaly (hepatic central venous congestion)
peripheral oedema
What is the main process behind transudate oedema?
changes in hydrostatic pressure in capillaries
What is the main process behind exudate oedema?
increased capillary permeability as reaction to inflammatory process
What components of oedema can be used to characterise the underlying process, and how?
Transudate - few proteins, low gravity
Exudate - lots of proteins, high gravity
What is the process underlying lymphoedema?
obstruction of lymphatic vessels
What are some examples of congestion in clinical practice?
DVT
Liver congestion in cirrhosis
Congestive heart failure
How does congestive heart failure arise, and what does it result in?
LV and/or RV not efficiently pumping blood out
LV - backlog and congestion in lungs = pulmonary oedema
RV - backlog and congestion in systemic veins and portal system = peripheral oedema and hepatomegaly
What can cause portal circulation congestion, and what are some potential consequences?
Portal systemic shunts:
- Oesophageal varices
- Caput medusae
How does LV failure cause oedema?
Reduced CO
Activation of RAAS
Increased water/salt retention
Fluid overload = oedema
What are the main forces controlling fluid in the vessels, and how do they lead to oedema?
- Hydrostatic forces: increased pressure in capillary due to congestion can force fluid out of vessel
- Oncotic forces: lack of proteins drawing fluid back into capillary can cause fluid buildup outside the vessel
How does lymphedema come about?
Blockage of lymphatic system at capillary bed
What type of oedema is found in congestive heart failure, and which starling force is at play?
Transudate oedema
Hydrostatic force imbalance
What are starling’s forces and what is their function?
Hydrostatic pressure and oncotic pressure
Keeps balance of fluid inside and outside capillary
At which point in circulation is hydrostatic or oncotic pressure higher?
Arterial circulation - hydrostatic force
Venous - oncotic force
What are the two mainly occurring types of haemorrhagic stroke and their prevalence?
- Intracerebral haemorrhage (9%)
- Subarachnoid haemorrhage (6%)
what are the two major ischemic heart conditions which call for CABG?
- left main stem stenosis
- three vessel disease
what is meant by three vessel disease?
obstruction of the RCA, LAD and Cx
what is left main stem stenosis?
stenosis of the bifurcation of the LCA into LAD and Cx
What are three main complications of CABG surgery?
cardiac tamponade
stroke
death
what can be some complications of open heart surgery (sternotomy)?
infection of the wound/wires sternal dehiscence (two sides grind agaisnt eachother) sternal malunion (sternal sutures come apart)
what are the main vessels used as bypass grafts?
mammary arteries
radial artery
reversed saphenous vein
which valve diseases are most commonly operated on, and when should surgery be carried out?
Aortic most common, then mitral
if valve disease severe
if there is large vegetations on valves
if renal function keeps dropping or fever persists
what options of valve replacements can be used?
pig valve (biological) mechanical valve
what are the benefits and disadvantages of the different types of replacement valves?
biological - less chance of infection; no warfarin; won’t last as long
mechanical - higher chance of infection; makes noise; will last a lifetime but also be on warfarin for life
which two organisms are most likely to cause what severity of infective endocarditis?
strep viridans - subacute IE
staph aureus - acute IE
what is a benefit of mitral valve repair over replacement?
it’s better to keep as much of the native valve as possible
IE affecting which types of replacement valves is more and less likely to be cured by only antibiotics?
native replacement valve - 90% chance of cure with only antibiotics
prosthetic valve - 50% chance of cure with only antibiotics
what is the classification of anti-arrhythmic drugs called, and how does it classify the drugs?
Vaughan Williams Classification
Class 1 - (1a,1b,1c): sodium blockers
Class 2 - beta blockers (reduce sympathetic activity)
Class 3 - potassium channel blocker (longer repolarisation)
Class 4 - calcium channel blockers (rate limiting)
what are the possible side effects of digoxin?
yellow vision
brady/tachicardia
VF/VT
nausea and vomiting
what are the main drugs used to treat atrial fibrillation?
beta blockers
class 1a sodium channel blockers (quinidine)
anticoagulants (warfarin or DOACs)
when are drugs like flecainide and amiodarone used in arrythmias?
in serious SVT, VT or arrhythmias not responding to beta blockers
what is the mechanism of action of digoxin and which patient population is likely to be on it?
positive inotrope, blocks ATPase pump
often given to elderly patients with kidney failure
what is the effect of the various sodium channel blockers on cardiac action potentials?
class 1a - longer AP, delay refractory period class 1b - shorter AP, accelerate refractory period class 1c - no effect on AP or refractory period, stronger sodium block
how is digoxin toxicity treated?
by stopping digoxin and administering Digibind
what are class 1b antiarrythmics used for?
severe VT and VF
give an example of antiarrhythmic medication for each Vaughan Williams classification
class 1a - quinidine class 1b - lidocaine, phenytoin class 1c - flecainide class 2 - bisoprolol, atenolol class 3 - amiodarone class 4 - verapamil, diltiazem
how can warfarin be counteracted and why?
with vitamin K
warfarin stops vitamin K activation (which helps production of clotting factors) –> administering vitamin K increases its levels in the blood
what are possible side effects of warfarin?
bleeding
teratogenicity
what is the effect of adenosine on paroxysmal ventricular tachycardia?
returns heart to sinus rhythm
