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