Flashcards in Vascular and Ischaemic Heart Disease Deck (241)
Where do the right and left coronary arteries arise from?
The base of the aorta
Where does most coronary venous blood drain into?
The coronary sinus and then into the right atrium
What area of the heart becomes deprived of blood supply if the left coronary artery becomes blocked?
Give four special adaptations of coronary circulation?
1. High capillary density
2. High basal blood flow
3. High oxygen extraction (75% compared to 25%)
4. Extra oxygen can only be supplied by increasing coronary blood flow
What does decreased PO2 do to the coronary arteries?
What is an intrinisc mechanism of coronary blood flow, and matches flow to demand?
What is a potent vasodilator for coronary blood flow (intrinsic mechanism)?
Adenosine from ATP
What type of nerves are coronary arterioles supplied by?
Sympathetic vasoconstrictor nerves
What are sympathetic vasoconstrictor nerves in coronary arterioles over-ridden by?
Metabolic hyperaemia as a result of increased heart rate and stroke volume
What does sympathetic stimulation of the heart result in?
Coronary vasodilatation despite direct vasoconstrictor effect
What substances activates beta-2-adrenoceptors, which causes vasodilatation?
What receptors does sympathetic stimulation act on in relation to coronary blood flow?
What do increased metabolites such as K, PCO2 and H+ do to coronary blood flow?
What does an increase in adenosine, do to coronary blood flow?
When does peak left coronary flow occur?
What does shortening diastole (e.g. very fast heart rate) do to coronary flow?
What gives blood supply to the brain?
Internal carotids and vertebral arteries
What is very sensitive to hypoxia in the brain?
What two arteries form the basilar?
Two vertebral arteries
What arteries anastomose to for the circle of Willis?
Basilar and carotid arteries
Where do the major cerebral arteries arise from?
The circle of Willis
What is caused by an interruption/cut-off of blood supply to a region of the brain?
What are the two main types of stroke?
1. Haemorrhagic bleeding
2. Ischaemic stroke
What type of stroke is described - blood leaks out of artery wall which is damaged?
What type of stroke is dewscribed - blood clot forms on atheroma on artery wall or comes from another part of body and gets stuck, blood cannot flow past?
What is autoregulation of cerebral blood flow guard against?
Changes in cerebral blood flow if mean arterial blood pressure changes within a range (60 - 160 mmHg)
In relation to autoregulation of cerebral blood flow: what happens to resistance vessels automatically when MABP rises?
Resistance vessels constrict to limit blood flow
When does autoregulation fail in relation to MABP falling?
What does MABP below 50 mmHg, result in?
Confusion, fainting and brain damage if not quickly corrected
What does increased PCO2 do to cerebral vessels?
Causes cerebral vasodilatation
What does decreased PCO2 do to cerebral vessels?
Cause vasoconstriction (which is why hyperventilation could lead to fainting)
What is the term for blood flow increasing to active parts of the brain?
What is normal intracranial pressure (ICP) within the skull?
8 - 13 mmHg
What is the equation for cerebral perfusion pressure (CPP)?
CCP = MAP - ICP
What two things could increase ICP?
1. Head injury
2. Brain tumour
What does increasing ICP, do to CPP and cerebral blood flow?
What are tight intercellular junctions called in cerebral capillaries?
The blood brain barrier
What are cerebral capillaries highly permeable to?
O2 and CO2
How does glucose cross the blood brain barrier?
By facilitated diffusion using specific carrier molecules
What three hydrophilic substances is the blood brain barrier exceptionally impermeable to?
What are the metabolic needs of the airways met by?
Systemic bronchial circulation
What is pulmonary artery BP typically?
20-25/ 6-12 mmHg
What is the pulmonary capillary pressure like compared to the systemic cappilary pressure?
What special adaptation of the pulmonary circulation protects against pulmonary oedema?
Absorptive forces exceed filtration forces
What causes vasoconstriction of pulmonary arterioles?
Why is resting blood flow in skeletal muscle low?
Because of sympathetic vasoconstrictor tone
In relation to skeletal muscle blood flow: during exercise what overcomes sympathetic vasoconstrictor activity?
In skeletal muscle blood flow, what does circulating adrenaline cause?
What does contraction of muscle aid in relation to veins?
What does skeletal muscle pump reduce the chance of?
Postural hypotension and fainting
What is the term for blood pooling in lower limb veins if venous valves become impotent?
Why do varicose veins not lead to a reduction of CO?
Because of compensatory increase in blood volume
What is the term for the result of imparied vascular perfusion depriving the affected tissue of nutrients (including oxygen). It can be reversible on multiple factors including speed of onset, local demand and duration?
What term refers to ischaemic necrosis of a dtissue or organ secondary to occlusion/reduction of the arterial supply or venous drainage. Recovery depends on a tissue regenerative ability?
What is the term for a set of well regulated processes that accomplish functions (1. maintaing blood in a fluid, 2. induce rapid, localised haemostatic plug at site of vascular injury)?
What is pathological/ corruption of haemostasis?
What is the term for the formation of a solid or semi-solid mass from the constituents of blood, within the vascular system, during life?
What are the three components of Virchow's triad?
1. Changes in vessel walls (endothelial injury)
2. Changes in blood constituents (hypercoaguability)
3. Changes in blood flow
What close small breaches in vessel walls and if activated in a vessel cause thrombus?
Name the two components of platelets?
1. Alpha granules (adhesion componenets, e.g. fibrinogen, fibronection, PDGF, anti-heparin)
2. Dense granules (aggregation, ADP)
What do platelets cause when contacting collagen or fibrin?
What maintains a permeability barrier and elaborates anticoagulant, antithrombotic, fibrinolytic regulators?
The endothelial cell
What four anticoagulant, antithrombotic and fibrinolytic regulators are elaborated in the endothelial cells?
3. Heparin-like molecules
4. Plasminogen activator
What three prothrombotic molecules does the endothelial cell elaborate?
2. Tissue factor
3. Plasminogen activator inhibitor
What does the endothelial cell use to modulate blood flow and vascular reactivity?
1. Vasoconstrictors - endothelin, ACE
2. Vasodilators - NO, prostacylcin
What three substances are used in regulation of inflammation and immunity in the endothelial cell?
1. IL-1, IL-6, chemokines
2. Adhesion molecules - VCAM-1, ICAM-1, E-selectin, P-selectin
Give three growth stimulators that regulate cell growth in endothelial cells?
Name two growth inhibitors that regulate cell growth in endothelial cells?
What are important contributory factors in thrombosis that disrupt laminar blood flow?
Turbulence and stasis
What refers to any alteration in the coagulation pathway which predisposes to thrombosis?
What two groups can conditions causing hypercoaguability be split into?
Acquired and Genetic
What are MI, immobilisation, tissue damage, cancer, prosthetic heart valves, DIC, heparin induced thrombocytopenia and antiphospholipid syndrome?
Acquired high risk hypercoaguable states
What are AF, cardiomyopathy, nephrotic syndrome, hyperoestrogenic states, oral contraceptive use, late pregnancy, sickle cell anaemia and smoking?
Lower risk aquired hypercoaguable states
Give three examples of genetic hypercoaguable states?
1. Factor V mutations
2. Defects in anticoagulant pathways - antithrombin III deficiency, protein C or S deficiency
3. Defects in fibrinolysis
What show lines of Zahn?
What two areas do mural thrombi take place?
Ventricles (heart) - MI, arrhythmias
Aorta (aneurysms) - atheroma
What thrombi are laminated due to alternating pale (platelet and fibrin) and dark (RBC/WBC) bands?
What is the term for a venous thrombi evoking inflammation?
What thrombi is most important in DVT of calf?
Venous thrombi (phlebothromboses)
What are large vessel thrombi prone to do?
What thrombi form reddish/blue casts and are adherent to the wall?
Give four fates of thrombi?
1. Propagation proximally (small to large vessel)
3. Resolution (fibrinolysis)
4. Organisation (granulation tissue, recanalisation)
What is the term for a detached intravascular solid, liquid ot gaseous mass which is carried by the bloodstream to a site distant from the point of origin?
Name a fluid embolism?
Amniotic fluid embolism
What travels via IVC to pulmonary circulation?
What can cause acute sudden death vs. segmental infarction (red infarcts), contrast with white infarcts?
Pulmonary thrombo embolism
How would you describe wedge shaped infarcts?
Wedge-shaped and firm
What is it important to remember in relation to venous emboli?
They do not cause infarcts in peripheral arterial circulation unless, atrial/ventricular septal defect, paradoxical embolus
What kind of embolism follows major soft tissue trauma and major bone fractures?
Give two steps/features of fat emboli?
1. Fatty marrow enters venules most globules arrest in lungs = dyspnoea
2. Some reach peripheral circulation = skin rashes, CNS confusion
What embolism can result from barotrauma (occurs in divers) and during delivery/abortion or iatrogenic?
How are vessels occluded in gas/air embolism?
Frothy bubbles occlude major vessels e.g. pulmonary artery
What embolism causes DIC (Disseminated intravascular coagulation), marked oedema and is post-partum?
Amniotic fluid embolism
How do amniotic fluid embolisms work?
Amniotic fluid and debris enters torn veins and embolises to lungs
What is a prostaglandin rich fluid?
What three disease patterns is arteriosclerosis a generic term for?
2. Monckeberg Medial Calcific Sclerosis
What arteriosclerosis type occurs in >50 years and involes calcification of medium sized arteries?
Monckeberg Medial Calcific Sclerosis
What can an atherosclerosis, ischaemic encephalopathy lead to?
What is the basic lesion in an atherosclerosis disease?
What two things occur as plaque size increases in atherosclerosis?
1. Luminal diameter decreases
2. Blood flow reduces
In atherosclerosis, what is a cause of more easily ingested by macrophages, acts as cehmotactic factors for monocytes, increase monocyte adhesion, induce antibody response, directly damage endothelial and smooth muscle cells and inhibit macrophage motility and trapping?
During atherosclerosis, when hypercholesterolaemia persists, smooth muscle proliferation and collagen deposition convert the fatty streak into what?
A mature fibrofatty atheroma
Which area of the aorta typically displays severe atheroma?
Bifurcation into iliac arteries
Give 4 complications of atherosclerosis?
1. Ulceration of athermatous plaque and thrombosis
2. Haemorrhage into plaque with plaque rupture and embolism of plaque contents
3. Ongoing narrowing = critical stenosis
4. Aneurysm formation
What results from inadequate systemic perfusion as a result of cardiac dysfunction?
In the clinical diagnosis of angina, what is the pain like and what is it from?
Visceral pain from myocardial hypoxia - hard to describe
What do provocation, relief and timing all lead to the clinical diagnosis of?
Pressing, sqeezing, heaviness, a weight. Radiating to arms, back, neck, jaw, teeth. Exertion, stress, cold wind, after meals. Few minutes, relieved by rest, GTN.
Give three features of peptic ulcer pain?
2. Boring and point of finger gesture
3. Relief by antacids/foods
What type of chest pain is focal, exacerbated by breathing, sharp and catching?
What is the pain like in dissection of aorta?
Tearing, excruciating, severe then eases
What is the gold standard investigation for CHD?
What two methods of revascularisation are there for reducing risk and symptoms of CHD?
What four drugs are there for CHD?
4. ACE inibitor
What is there a risk of 8-10 years post-op in coronary artery bypass?
Give 4 complications of CABG?
What do these steps describe: vascular access, antiplatelet/coagulation, catheter to ostium of coronary, guidewire down vessel, balloons threaded over wire, stents implanted, balloon catheter and wires removed?
What are two indications for angiography?
1. Severe symptoms
2. High risk
What are 4 indications for aborting revascularisation?
1. Multi-vessel disease
3. Left main disease
What revascularisation is done in a STEMI?
What revascularisation is done in acute coronary syndrome?
Angiography with a view to revascularisation
What revascularisation is done in chronic stable angina?
Revascularisation for severe symptoms or high risk
What 2 vasculitis diseases can be risk factors for DVT/PE?
1. SLE and lupus anticoagulant
2. Behcet's disease
Give 4 things related to drugs and medications that can be risk factors for DVT/PE?
1. IV drug abuse
2. Oestrogens - ORP and HRT
What blood test would you do to investigate DVT?
What are di-dimers?
Fibrin breakdown products
What five other conditions can raise d-dimers?
4. Liver disease
What imaging would you use to investigate DVT?
What technique for investigating DVT involves: strain gauge around affected limb, venous emptying by compression, measure refill time (fast = not much, empty = clot)?
What should be done when diagnosing DVT if there is high PTP score, but negative d-dimer and USS?
No DVT, consider other differentials
What should be done when diagnosing DVT if there is a high PTP score, positive d-dimer but negative USS?
Repeat assessment, repeat USS later
What are two treatment methods for DVT?
1. anticoagulation with LMWH and warfarin
2. Compression stockings
What is phlegmasia dolens and what can it cause?
DVT causing obstruction of arterial inflow - severe DVT, background PAOD
Can cause venous gangerene
Give three treatments for Phlegmasia dolens?
1. IVC filter
2. Femoral arterial line
3. tPA intra-arterially
What are SOB, collapse, pleuritic chest pain, haemoptysis and sudden death causes of?
What is oligemia on CXR and what can it be a sign of?
Segmental loss of pulmonary vasculature - PE
What heart sounds can be heard in PE?
Fourth heart sound or accentuated pulmonic component of the second heart sound
What can a pleural rub, tachypnea, hypotension, cardiorespiratory arrest, wheeze, tachycardia and signs of pleural effusion all be found in?
What, on the ECG is only seen in 20% of PE cases?
S1, Q3, T3
What are four main investigations for PTE?
1. Arterial blood gases
3. V/Q scan
When should a V/Q scan be performed to investigate a PE?
Within 48 hours
What investigation for PE is poor for more peripheral lesions and involves breath holding/IV contrast?
CT pulmonary angiogram
What can potentially be the four main treatments for PE?
2. Thrombolytic therapy
3. IVC interupption - IVC filter/surgery
4. Surgical removal
What is the treatment for a massive PE with shock or syncope?
Thrombolysis or surgery
What is the treatment for a major PE with right-ventricular dysfunction?
Anticoagulants and thrombolysis
What is the treatment for a major PE without reight-ventricular dysfunction?
What is the treatment for a minor PE?
What anticoagulant is used for initial treatment of PE?
What induction period with heparin is associated with a lower rate of recurrent PE?
What would be used for PTE treatment in these cases: recurrent PTE despite adequate anticoagulation, PTE when coagulation cannot be used (post-op) and high risk patients (phlegmasia dolens)?
Give an indication for surgery (pulmonary embolectomy) in PTE?
Chronic thromboembolism pulmonary hypertension
Name two anticoagulation vitamin K antagonists for PTE?
Wrfarin and phenindione
Name an antithrombin drug used as anticoagulation therapy in PTE?
Name two anti Xa drugs used as anticoagulation in PTE?
Apixaban and rivaroxaban
Where are the four vitamin K dependent clotting factors synthesised?
In the liver
What are the four vitamin K dependent clotting factors?
What drug acts as an anticoagulant by blocking the ability of vitamin K to carboxylate the vitamin K dependent clotting factors, therefore reducing their coagulant activity?
What three things is warfarin used in teh prophylaxis/and or treatment of?
1. Venous thrombosis and its extension
2. Pulmonary embolism
3. Thromboembolic complications associated with AF and cardiac valve replacement
What is a mathematical correction that normalises the PT ratio by adjusting for the variablity in the sensitivity of the different thromboplastins?
Give four conditions where warfarin therapy is contraindicated?
2. Bleeding diathesis
3. Uncontrolled alcohol/drug abuse
4. Unsupervised dementia/physhosis
What does heparin bind directly to, to inactivate it?
What factors does heparin inactivate?
How is heparin dosing monitored?
By activated partial thromboplastin time (APTT)
What is a large molecule, cross links thrombin with antithrombin, thrombin inhibition 4 fold compared to action on factor Xa, unpredictable and needs monitored?
What is a small molecule, no cross links, thrombin inhibition 1 to 1 with action of factor Xa, predictable by weight and needs no monitoring?
Which has less osteopenia, LMWH or UFH?
Give four cautions and caveats of LMWH?
1. Dosing in obesity and in renal insufficiency
2. Dosing in pregnancy
3. Protamine reversal
4. Interchangeability of different preperations
How long is the duration of therapy for PE in a temporary risk factor?
How long is the duration of therapy for PTE in an idiopathic PE?
How long is the duration of therapy for PTE in a second idiopathic event?
What are inherited thrombophilia (not factor V Leiden or prothrombin mutation), antiphospholipid syndrome, recurrent idiopathic VTE, malignancy and thromboembolic pulmonary hypertension?
Potential indications for indefinite anticoagulant therapy
For oral anticoagulation, what remains the only option?
Vitamin K antagonists
Give three things you would monitor with anti-thrombin drugs?
1. Monitor aPTT
2. Thrombin time for DTIs
3. Ecarin clotting time
What is used to reverse dabigatran?
Recombinant factor VIIa, FFP and dialysis
How do you reverse FXa inhibitors?
Prothrombin complex concentrate (PCC)
What occurs when insufficient blood reaches exercising muscle?
The patient is pain-free at rest, but after exercise develops ischaemic pain in the affected limb, which is relieved by rest.
Name a protective factor for intermittent claudication?
List two non-invasive investigations for lower limb ischaemia?
1. Measurement of ABPI
2. Ultrasound scanning
Name 3 invasive investigations for lower limb ischaemia?
1. Magnetic resonance angiography
2. CT angiography
3. Catheter angiography
What does ABPI stand for?
Ankle Brachial Pressure Index
What is the equation for ABPI?
Ankle pressure / brachial pressure
What is a normal ABPI level?
0.9 - 1.2
What is a claudication ABPI level?
0.4 - 0.85 (-1)
What is a severe ABPI level?
0 - 0.45
Give four ways of improving claudication symptoms?
1. Exercise training
What intensity of exercise should you be doing with intermittent claudication?
1 hour per day
30 minutes 3 times per week for 6 months
Name a drug used for intermittent claudication?
Give two types of critical limb ischaemia?
1. Rest pain - toe/foot ischaemia (nerve ending pain)
2. Ulcers/gangrene = severe ischaemia + damage
What is rest pain, in toes and forefoot, worse at night, helped by sitting and putting the leg in a dependent position and helped by getting up and walking about?
Critical limb ischaemia
What are two major risk factors for amputation in critical limb ischaemia?
What are 3 methods of treatment for critical limb ischaemia?
3. Surgical reconstruction/amputation
What patients are more likely to develop intermittent claudication and critical limb ischaemia?
Males > 55 years
What does this pathogenesis describe: medial degeneration, regulation of elastin/collagen in aortic wall, aneurysmal dilatation, increase in aortic wall stress and progressive dilatation (law of laplace)?
Abdominal Aortic Aneurysm
What size are true arterial aneurysms?
50% increase in normal diameter (1.2 - 2cm)
What are the three main risk factors for abdominal aortic aneurysm?
Female, smoker, hypertensive
What are these symptoms of: tachycardia, hypotensive, pulsatile, expansile mass +/- tender, transmitted pulse and perihperal pulses?
What two investigations are done for AAA?
2. CT scan
What investigation only tells us if there is an AAA, not its AP diameter?
What investigation for AAA, allows identification of shape, size, iliac movement and allows for management planning? It is also the only method to identify ruptured AAA?
What type of operations are elective aneurysm repairs?
What type of operation is an emergency aneurysm repair?
What can be done during intervention of an abdominal aortic aneurysm?
Endovascular aneurysm repair (EVAR)
In open/laparotomy repair of an abdomoinal aortic aneurysm, what graft is used?
What patients are abdominal aortic aneurysms commonly found in?
Males > 60
What three veins are part of the deep system in the leg?
What two veins are part of the superficial system in the leg?
What is the term for dilated, tortuous superficial veins, due to transmission of deep vein pressure?
What can you get varicose veins following?
What two conditions increase the deep veins pressure and can cause varicose veins?
1. Deep vein obstruction
2. Deep valve incompetence
What are 4 signs of varicose veins?
1. Dilated and tortuous superficial veins
2. More prominent with standing
3. Arising in groin or behind the knee
4. Complications of varicose veins
What are three clinical features of chronic venous insufficiency?
1. Haemosidering deposits
What are bleeding and bruising, superficial thrombophlebitis and chronic venous insufficiency all complciations of?
What is thrombophlebitis?
Inflammation of a vein caused by a blood clot
What is the term for irreversivle skin damage as a result of sustained ambulatory venous hypertension?
Chronic venous insufficiency
What is a break in the skin, between malleoli and tibial tuberosity, presumed to be due to venous disease?
Chronic venous ulcer
What are haemosiderin deposits caused?
Red cell leakage, red cell breakdown and haemosiderin (iron)
What can superficial reflux (LSV and/or SSV), deep reflux, deep venous occlusion, mixed superficial and deep disease, perforating vein reflux and abnormal calf pumps cause?
What are the two main issues ultrasound focuses on in relation to varicose veins?
1. State of the deep veins (occlusions or impotence)
2. Saphenofemoral or saphenopopliteal incompetence
What is graduated compression as a management for varicose veins contraindicated in?
Name three types of interventional, endovenous management methods for varicose veins?
1. Foam sclerotherapy
2. Endovenous ablation
3. Surgical - high tie, stripping or foam, multiple stab avulsions or foam
Give four complications of intervention of varicose veins?
2. Skin staining
3. Local ulceration
What is acute onset of focal neurological symptoms and signs due to disruption of blood supply?
In a haemorrhagice stroke: what two factors can weaken blood vessel walls?
1. Structural abnormalities like aneurysm, arteriovenous malformation (AVM)
2. Inflammation of vessel wall (vasculitis)
What are three modifiable risk factors for stroke?
What is homocysteinemia a rare cause of?
What can protein S, C and antithromboin III deficiency cause (rarely)?
What 4 genetic causes of stroke are there?
1. Factor V Leiden mutation
2. Common prothrombin mutation
3. MELAS + CADASIL
4. Fabry's disease
What can hypoglycaemia, siezure and migraines mimic?
What is the only way of differentiating between ischaemic and haemorrhagic stroke?
What are three brain imaging techniques used for stroke?
1. CT Brain +/- angiography
2. MRI with DWI +/- angiography
3. MRI with GRE - looks for old haemosiderin deposits
What does LVH on an ECG suggest?
Uncontrolled hypertension which is common cause of AF
What embolism infarcts in same side as affected carotid artery?
What embolism infarcts in more than one arterial territory, bilateral?
If there is a haemorrhagic stroke in a young patient, what two underlying conditions will you investigate for?
If there is a haemorrhagic multiple bleed, what two conditions would you look for?
Moya Moya disease
(using cerebral amyloid angiopathy
What two drugs do you give for initial management of TIA/stroke?
Aspirin 75mg + dipyridamole MR 200mg twice daily/clopidogrel 75mg daily
What along with antiplatelets, what three drugs would you give for TIA/stroke managmenet?
2. Anticoagulate if AF
What are three surgical managements for TIA/stroke?
1. Haematoma evacuation
2. Relief of raised intracranial pressure
3. Carotid endarterectomy
What surgical management would you do for obstructive hydrocephalus and large total MCA infarctions?
Relief of intracranial pressure
What surgical management would you do for a patient with >70% stenosis in same sided internal carotid artery?