Cardiovascular Flashcards
At what percentage stenosis would you typically get symptoms of angina?
> 70%
Give a genetic cause of stable angina
Hypertrophic cardiomyopathy
If blood flow is reduced/ there is myocardial thickening, which part of layer of the heart is most affected?
Subendocardium
Why is chest pain felt with stable angina?
Subendocardial ischaemia leads to the release of adenosine and bradykinin which stimulate myocardial nerve fibres and alter pain sensation
Describe the symptoms of stable angina
Pressure/ squeezing pain that radiates to the left arm, jaw and shoulders
SOB
Diaphoresis
Describe vasospastic angina
Ischaemia from coronary artery vasospasms as smooth muscle around the arteries constrict
There is no correlation with exertion and all layers are affected
What ECG changes would you expect to see in stable and unstable angina?
ST segment depression from subendocardial ischaemia
What ECG changes would you expect to see in vasospastic angina?
ST segment elevation
How would you treat angina and in which case would you give calcium channel blockers?
Nitroglycerin spray, give CCB in vasospastic angina
How does the formation of an atherosclerotic plaque lead to a myocardial infarction?
Damage to the tunica intima of the endothelium- fat, cholesterol, proteins, calcium, WBCs accumulate and a hard fibrous cap forms
The cap breaks and exposes soft interior which platelets can adhere to and completely block the artery
Which area of the heart is supplied by the right coronary artery?
Posterior wall, septum and papillary muscles of the L ventricle
Which area of the heart is supplied by the L circumflex artery?
Lateral wall of the L ventricle
Which area of the heart is supplied by the L anterior descending artery?
Anterior wall and septum of L ventricle
Where is the first area affected in an MI and what ECG changes would you expect to see at this stage?
Inner 1/3 of myocardium- subendocardial infarct
ST segment depression
NSTEMI
What typically happens 3-6 hours after an MI?
Effects become transmural and ECG shows ST elevation: STEMI
Give 5 symptoms of a myocardial infarction
Crushing chest pain- referred to L arm and jaw Diaphoresis Nausea Fatigue Dyspnoea
How would you diagnose a myocardial infarction?
Myocardial cells in the blood stream:
Troponin I and T - elevated 2-4 hours, peak at 48 hours, stay elevated for 7-10 days
CK-MB- elevated for 2-4 hours, peak at 24 hours, normal at 48 hours
Give 5 possible complications of myocardial infarction
Arrhythmias- damage to cells disrupts signals
Cariogenic shock- can’t pump enough blood
Pericarditis-1-3 days
Myocardial rupture- macrophages invade, granulation tissue, 3-14 days
Scarring- after 2 weeks
Give 3 types of therapy used to treat MI
Fibrinolytic therapy- medications
Angioplasty- surgical removal
Percutaneous coronary intervention- stent
Describe the risk of reperfusion injury after an MI
Influx of calcium- damaged cells contract but become stuck
Formation of reactive oxygen species which can damage cells
Give examples of medications that may be given after or in order to prevent an MI
Antiplatelets- aspirin Anticoagulants- heparin Nitrates- relax coronary arteries and lower preload Beta blockers- slow HR Pain medication Statins- improve lipid profile
Give the ejection fraction with the percentages for normal and HF
Stroke volume/ total volume
Normal= 50-70%
Systolic HF= < 40%
Why is the ejection fraction normal in diastolic HF?
Stroke volume and total volume are both low so fraction is not affected
Give 5 causes of L sided heart failure
Long standing HTN Ischaemic HD Dilated cardiomyopathy Concentric hypertrophy - diastolic HF Restrictive cardiomyopathy- diastolic HF
How does L sided heart failure lead to a build up of fluid?
Less blood to the kidneys activates the Renin-angiotensin aldosterone system and causes fluid retention
This is in order to increase BP, increase filling and therefore contraction strength
Fluid leaks from blood vessels causing oedema
How does pulmonary oedema occur as a result of L sided heart failure and what symptoms does this cause?
Back up of blood increases pressure in the pulmonary artery leading to oedema, this causes:
Dyspnoea
Rales
Blood can leak into the alveoli
How can R sided heart failure occur as a result of an atrial or ventricular septal defect?
Blood is shunted L to R
Increase fluid volume in R atrium/ ventricle leads to concentric hypertrophy
Ischaemia- systolic dysfunction
Small volume- diastolic dysfunction
How can chronic lung disease lead to R sided heart failure?
Pulmonary HTN makes it harder for R side to pump against pressure, this causes Cor Pulmonalae
As a result there is systemic vein congestion:
Jugular venous distention
Hepatosplenomegaly- cirrhosis/ liver failure
Ascites
Pitting oedema
How would you treat heart failure?
ACE inhibitors
Diuretics
Give 4 risk factors for hypertension
Old age
Obesity
Salt-heavy diet
Sedentary lifestyle
Give 4 causes of secondary HTN
Low renal blood flow: Atherosclerosis Vasculitis Aortic dissection Fibromuscular dysplasia (non-inflammatory, non-atherosclerotic growth of the artery)
Give the BP values for a hypertensive crisis
Systolic >180mmHg
Diastolic >120mmHg
Describe atrial flutter
Atria contract at high rates of around 300bpm
Give the difference between type I and type II atrial flutter
I- moves around tricuspid valve counterclockwise
II- exact location less defined
How might ischaemia lead to atrial flutter?
Heart cells are more irritable and this changes their properties to reentrant circuit is more likely to develop
Why is ventricular bpm usually <180 bpm and what implication does this have in atrial flutter?
AV node has a relatively long refractory period, so there is an atrial:ventricular ratio where QRS complex will only appear once every 2/3 atrial contractions
Give 4 symptoms of atrial flutter
SOB
Chest pain
Dizziness
Nausea
What is the risk in atrial flutter as there is ineffective contraction?
Blood stagnates and forms clots which can go to the brain and cause a stroke
How can atrial flutter lead to heart failure?
Prolonged tachycardia causes ventricles to decompensate
How would you treat atrial flutter?
Anticoagulants
Beta blockers
Calcium channel blockers
Describe bundle branch block
Electrical signal blocked along the bundle branches due to fibrosis:
Ischaemia, MI, myocarditis
HTN, coronary artery disease, cardiomyopathies
What happens if there is a R bundle branch block? What ECG changes would be seen?
Electrical impulse travels down L bundle branch and L ventricle contracts, the R ventricle then contracts late
There is therefore a wide QRS complex
V1- M shape
V6- W shape (MARROW)
What ECG changes would you expect to see in L bundle branch block?
V1- W shape
V6- M shape (WILLIAM)
Describe long QT syndrome
Abnormally long depolarisation in some heart cells
What causes long QT syndrome?
Dysfunctional L-type calcium channels which let in more calcium ions and causes early after-depolarisation so ventricles depolarise and contract prematurely which causes reentrant tachycardia (150-250bpm)
Give 3 symptoms of long QT syndrome
Palpitations
Dizziness
Syncope
Give 2 causes of long QT syndrome
Congenital Medication- class IA and III anti-arrthymics
Describe Wolf-Parkinson-White syndrome
An accessory pathway is present connecting the atria and ventricles, this is called the bundle of Kent and leads to the pre-excitation of ventricles
What ECG changes would you expect to see with Wolf-Parkinson-White syndrome?
Short PR interval
Long QRS complex
How can Wolf-Parkinson-White syndrome facilitate arrhythmias?
Atrial arrhythmia + bundle of Kent means that ventricular rate is equal to the atrial rate and therefore cariogenic shock occurs as there is no time for the heart to refill
Describe the causes of aortic dissection
Chronic HTN- stress, increase in blood volume
Weakened aortic wall
With aortic dissection, where may blood back up into and what effects could this have?
Pericardial space- pericardial tamponade
Mediastinum- if tunica media tears
Back into the true lumen and renal/ subclavian arteries may be compressed by false lumen causing a low blood flow to the kidneys and arms
Give 5 symptoms of aortic dissection
Sharp chest pain which radiates to the back Weak pulse in downstream artery Difference in BP between L and R arms Hypotension Shock
How would you treat aortic dissection?
Surgically: Removal of dissected aorta Wall constructed with synthetic graft Sometimes propped open with stent BP medications: beta blockers
Give 5 causes of pericarditis
Idiopathic Viral Dressler syndrome- after MI Ureic pericarditis- high blood urea Autoimmune- immune system attacks pericardium Cancer/ radiation Medications- penicillin/ anticonvulsants
Describe the process of chronic pericarditis
Immune cells cause fibrosis of the pericardium making it stiff and restrictive so the heart struggles to relax/ expand
This leads to a decrease in stroke volume and an increase in heart rate
Give 2 symptoms of pericarditis and 2 symptoms of a large pericardial effusion
Fever
Chest pain: worse on heavy breathing and better leaning forward
Decreased heart sounds
Decreased cardiac output
SOB, low BP, dizziness
What would you hear through a stethoscope with pericarditis?
Thickened layers rub against each other, this is called a friction rub
What ECG changes would you expect to see with pericarditis?
Acute: ST elevation, PR depression, T wave starts to flatten, eventually returns to normal
Pericardial effusions: low QRS complex voltage
Alterans- QRS complexes have different heights as a result of the heart swinging back and forth in fluid
How would you treat pericarditis?
Relieve pain
Treat cause
Pericardial effusion- pericardiocentesis
Describe the difference between organic PVD and functional PVD
Organic- obstruction/ blockage of peripheral vessels
Functional- constriction of peripheral vessels
How ischaemia due to PVD lead to claudication?
Ischaemic cells release adenosine which is a signalling molecule that affects nerves in this area and this is felt as pain
Which artery would you suspect in PVD with pain in: Hip/ buttocks Thigh Upper 2/3 of calf Lower 1/3 of calf Foot
Aorta/ iliac Iliac/ common femoral Superficial femoral Popliteal Tibial
Give 2 symptoms of peripheral vascular disease other than pain
Ulcers on the feet that do not heal normally
Colour changes- elevation pallor and dependent rubor
Give 4 risk factors for peripheral vascular disease
Smoking
Diabetes
Dyslipidemia
HTN
How would you diagnose PVD?
Listening to iliac arteries with a stethoscope for “whoosh” or bruit, due to narrowing
Doppler ultra sound to look at blood flow
Ankle-brachial index (ABI) - comparison of two BPs
Give the equation for the ABI and the value used to diagnose PVD
Systolic BP in ankle/ systolic BP in arm <0.9
Give 3 causes of aortic valve stenosis
Stress over time- damages endothelial cells around the valves which leads to fibrosis and calcification
Bicuspid aortic valve- more stress per leaflet
Chronic rheumatic fever- repeated damage and repair causes commissural fusion
Explain why you hear an “ejection click” and murmur with aortic stenosis
Ventricle contracts and pressure increases until valve eventually opens- ejection click
Blood is moving through a narrow opening causing a murmur
What type of murmur do you hear with aortic stenosis?
Crescendo-Decrescendo murmur as it gets louder and then quieter as blood flow subsides
What is the result of increased ventricular pressure in aortic stenosis?
Concentric left ventricular hypertrophy- new sarcomeres are added in parallel to existing ones
What is microangiopathic haemolytic anaemia and why does it occur in aortic stenosis?
Damage to WBCs as they are forced through the smaller valve and split into schistocytes leading to haemoglobinuria
What is the treatment for aortic stenosis or regurgitation?
Valve replacement
Describe the causes of aortic regurgitation
Aortic root dilation- leaflets are pulled apart
Causes: idiopathic, aortic dissection, aneurysms, syphilis
Valvular damage- infective endocarditis, chronic rheumatic fever
Fibrosis- cannot form a seal and blood leaks through
What type of murmur would you hear with aortic regurgitation?
Early decrescendo diastolic murmur due to blood flowing back through the valve
Why do you get an increase in pulse pressure with aortic regurgitation?
Increase in L ventricular blood volume due to back flow, therefore increase in stroke volume and systolic BP
Less blood in aorta during diastole therefore a drop in diastolic BP
Give the symptoms of a hyperdynamic circulation as found in aortic regurgitation
Bounding pulse, head bobbing, capillary beds of fingernails pulsate (Quincke’s sign)
What is myxomatous degeneration and how can it cause mitral valve prolapse?
Weakened connective tissue which increases the leaflet area and increases the chordae tendineae length which can then rupture- this can cause the posterior leaflet to fold into the atrium
Give the signs and symptoms of mitral valve regurgitation
Usually asymptomatic
Heart murmur- mid-systolic click and systolic murmur
Give 3 causes of mitral valve regurgitation
Damaged papillary muscles as a result of an MI
L sided HF leading to left ventricular dilation
Rheumatic fever-chronic rheumatic HD- leaflet fibrosis
How can mitral valve regurgitation cause L sided heart failure?
With every contraction some blood goes back to the L atrium, this then drains back into the ventricle which increases preload causing eccentric hypertrophy
Give the main cause of mitral valve stenosis
Rheumatic fever- commissural fusion
What are the consequences of mitral valve stenosis?
Increased volume in atrium therefore increased pressure
Dilation due to increased pressure, leading to pulmonary congestion and oedema- Dyspnoea
Pacemaker cells stretch due to dilation and become more irritable and prone to atrial fibrillation- stagnant blood- thrombosis
There is also extra blood in the pulmonary system causing HTN
How can mitral valve stenosis lead to dysphagia?
If atria dilates enough due to increased load, it can compress the oesophagus
How would you treat mitral valve disease?
Valve repair
Surgical replacement of the valve
What are the two factors that ultimately determine blood pressure?
Resistance to flow and cardiac output
What are the two sub-types of hypovolemic shock?
Hemorrhagic and non-hemorrhagic
Give an example of non-hemorrhagic shock
Severe dehydration
Approximately how much blood can be lost before there is a likely risk of shock
20% loss (around 1L)
What chemicals are released as a result of decreased cardiac output?
Catecholamines
-adrenaline and noradrenaline
ADH
Angiotensin II
What is mixed venous oxygen saturation and how is it affected in hypovolemic and cariogenic shock?
Amount of oxygen bound to haemoglobin returning to the R side of the heart from the tissues
Decreased MVO2
What is the most common cause of cardiogenic shock?
Acute myocardial infarction- muscle cells die leading to weaker contractions and therefore decreased stroke volume
Describe distributive shock
Damaged endothelial cells leading to excessive dilation of blood vessels and leaky blood vessels
How does increased dilation of blood vessels cause distributive shock?
Increased dilation of blood vessels decreases resistance to flow causing a drop in BP
How does septic shock occur?
Endotoxins (lipopolysaccharides) found in the outset membrane of gram negative bacteria lead to lower perfusion
How does the damage of endothelial cells by bacterial endotoxins lead to vasodilation?
Endothelial cells release vasodilators such as nitric oxide
They activate the complement pathway causing mast cells to release histamine
What is the procoagulant produced by endothelial cells?
Tissue factor
Why does low vascular resistance lead to reduced oxygen perfusion to the tissues?
Blood is moving too fast to unload the oxygen, there is a drop in oxygen despite increased blood flow
Give the three sub-types of distributive shock
Septic
Anaphylactic
Neurogenic shock
Describe the formation of the atrial septum in a foetus
Septum primum grows, osmium primum is present
Septum primum fuses with the endocardial cushion and closes the gap completely, ostium secundum appears
Septum secundum forms with foramen ovale present
What is the most common cause of an atrial septal defect?
Septum secundum doesn’t grow enough during development
Which conditions are atrial septal defects strongly associated with?
Foetal alcohol syndrome
Down’s syndrome
Describe the movement of blood with an atrial septal defect and how this affects oxygen saturation
Higher pressure in left side of the heart means blood is shunted from L to R
Increased oxygen saturation in R atrium, R ventricle, pulmonary artery
How does the extra blood in the R side of the heart affect the pulmonary valve with atrial septal defect?
Delayed pulmonic valve closure
What causes a ventricular septal defect?
If upward growing muscular ridge and downward growing membranous region don’t fuse- commonly defect in membranous region
Describe blood flow with a ventricular septal defect and how this affects oxygen saturation
Blood flows from R ventricle to lungs since pressure is higher in L ventricle than R
Blood is shunted from L ventricle to right since pressure is higher in L
Increased oxygen saturation in R ventricle and pulmonary artery
How might pulmonary HTN occur with a ventricular septal defect and what are the implications of this?
Increased blood shunted to R side of the heart can cause pulmonary HTN, if pressure on R side then exceeds the left, blood is shunted from R to L, this is called Eisenmenger’s syndrome
Non-oxygenated blood is pumped into the systemic system- cyanosis
Describe dilated cardiomyopathy
Dilation of the heart chambers means contractions are weaker, decreasing stroke volume and causing biventricular congestive heart failure
How does dilated cardiomyopathy affect the heart valves
Stretches out the valves that separate the ventricles causing mitral or tricuspid valve regurgitation
Give 2 conditions caused by dilated cardiomyopathy
Valve regurgitation
Arrhythmias- stretching cells causes irritation
Give 5 causes of dilated cardiomyopathy
Idiopathic Genetic mutation Infection Alcohol abuse Drugs Peripartum cardiomyopathy- pregnancy
How would you treat dilated cardiomyopathy?
L ventricular assist device
Heart transplant
Give 5 causes of secondary HTN (other than kidney or endocrine disorders)
Anaemia Drugs Cancers Pregnancy Neurological disorders Hormonal contraceptives
Give 4 causes of kidney related secondary HTN
PKD
Chronic glomerulonephritis
Renovascular HTN
Renal tumours
Give 5 endocrine disorders which cause HTN
Neurogenic HTN Hyper/hypothyroidism Acromegaly Hyperparathyroidism Hyperaldosteronism (Conn's syndrome)
What ECG changes would you expect to see with atrial fibrillation?
“Scribble” instead of P wave
Irregular QRS complex intervals
100-175bpm
Give 4 risk factors for atrial fibrillation
CVD
Diabetes
Obesity
Genetics
What is tissue heterogeneity?
Cells develop different properties
Describe the difference between the multiple wavelet theory and the automatic focus theory to explain atrial fibrillation
Multiple wavelet theory suggests multiple cells responsible firing off ‘wavelets’ which may trigger other ‘wavelets’
Automatic focus theory suggests one specific area initiates AF located in the cardiac muscle around the pulmonary veins
Describe the difference between paroxysmal, persistent and longstanding persistent AF
Paroxysmal comes and goes
Persistent > 7 days
Longstanding persistent >12 months
Why do repeated episodes of paroxysmal AF lead to persistent AF?
Stress
Calcium overload
Progressive fibrosis
Give 5 symptoms of AF
Fatigue Dizziness SOB Weakness Palpitations
Give a common complication of AF and explain why this is a risk
Stroke, as blood stagnates making it more likely to clot
How would you diagnose AF?
Persistent AF: ECG
Paroxysmal AF: Holter monitor which is a portable device monitoring heart activity for an extended period of time
How would you treat AF?
Medication to control HR and reduce clotting
Pacemaker
Radio-frequency catheter oblation
Define ventricular tachycardia
More than 3 consecutive PVCs
> 100 ppm but can experience up to 450bpm
Give 5 symptoms of ventricular tachycardia and explain why these occur
Less blood pumped out with each heartbeat as there is not enough time to refill, this causes: Chest pain Fainting Dizziness SOB Sudden death
Describe focal ventricular tachycardia
The cells have an abnormal automaticity, ventricular cells usually have an automaticity of 30bpm but these can become stressed/ irritated and the automaticity can increase past that of the SAN
Give 4 examples of ways in which the ventricular cells can become irritated causing ventricular tachycardia
Medications
Illicit drugs
Electrolyte imbalances
Ischaemia
Describe how reentrant ventricular tachycardia may occur
Heart cells are damaged/ dead and form scar tissue which is less conductive
Impulse travels around dead tissue in a loop, variability in conduction speed and refractory period can lead to reentrant loop occurring
Describe the difference between monomorphic and polymorphic ventricular tachycardia
Monomorphic- reentrant and focal (one group responsible)
Polymorphic- multiple areas of ventricular cells are affected, signal is originating from different groups
How would you treat ventricular tachycardia?
Cardioversion
Medication to lower HR to normal
Electrical pulse delivered to heart on R wave, avoid T wave as this is a vulnerable period
Radio-frequency catheter oblation
Device implantable cardioverter defibrilation
What are the two types of true aneurysm?
Symmetrical- fusiform aneurysm
Asymmetrical- saccular/ berry aneurysm
What is a pseudoaneurysm?
Gap in the artery wall and blood pools due to surrounding connective tissue
What percentage of aneurysms are abdominal compared to thoracic?
60% abdominal
40% thoracic
Where is the most common place to find an abdominal aneurysm?
Below renal arteries, above aortic bifurcation
There is less collagen and therefore the arteries are weaker
Describe how obstruction of the vasa vasorum supplying the first section of the aorta can cause weakening of the aortic wall
Hyaline arteriosclerosis of the vasa vasorum
Narrowing of the lumen leads to ischaemia and smooth muscle atrophy
This weakens the aorta’s wall
How can the formation of an atherosclerotic plaque cause weakening of an artery wall
Oxygen can’t penetrate the plaque and therefore cannot reach the wall
Give 4 risk factors for aneurysms
Male
>60
HTN
Smoking
How can syphilis cause an aneurysm?
Causes inflammation of the vasa vasorum (endarteritis obliterans), this causes narrowing of the vessels and so no blood flow
How do mycotic aneurysms occur?
Caused by infection
Infection breaks off and travels to visceral, intercranial/ arteries feeding arms and legs
They weaken the vessel wall
Give 3 bacteria and 2 fungi which can cause mycotic aneurysms
Bacteroides fragilis
Pseudomonas aeruginesa
Salmonella (any)
Aspergillus
Candida
Which genetic disorders can lead to aneurysm formation?
Anything affecting the connective tissue
Marfan syndrome- elastic properties compromised
Ehlers Danlos syndrome- ability to form collage is impacted
What effect can a thoracic aneurysm have on the aortic valve?
Pulls on the valve so it can’t close properly
Blood therefore flows back into the ventricle and there is aortic insufficiency
There may also be a cough if the L recurrent laryngeal nerve is stretched by the aneurysm
Describe a brain aneurysm rupture
Blood pools into subarachnoid space, increases pressure which irritates the meninges
This causes a headache and inability to flex the neck forwards
How can aneurysms cause blood clots?
Blood may be pulled into the extra lumen space
It is not moving as quickly as the rest of the blood- stagnates and is therefore likely to clot
Give 3 signs/ symptoms of abdominal aortic aneurysms
Severe L flank pain
Pulsating mass with heartbeat
Hypotension
How might a thoracic aneurysm present?
Usually asymptomatic
May be chest/ back pain
