Topic 2 - Cardiovascular Disease Flashcards
Describe the structure of a healthy heart and how it works.
Two atria and two ventricles.
SAN is where action potential is induced. This is done by the action of parasympathetic and sympathetic innervation from the vagus nerve and circulating catecholamines. Parasympathetic includes acetylcholine which reduces heart rate, and sympathetic include noradrenaline which increases heart rate.
Action potential passes to the AV node. There is a delay in this firing off an action potential to allow for the filling of the ventricles and emptying of the atria.
The AV node fires an action potential which goes down the Bundle of His to the Purkinje fibres. This causes contraction of the ventricles and ejection of blood out of the heart.
Describe how to analyse an ECG.
P wave - atrial depolarisation
PQ segment - time where electrical activity travels from atria to ventricles
QRS complex - ventricular depolarisation.
ST segment - time between ventricles depolarising and repolarising (contraction)
Define heart failure and list the types.
What effect does it have on CO?
Heart failure is where the there’s disease because of insufficient function of the heart.
Systolic failure - inefficient ejection of blood e.g. caused by coronary heart disease
Diastolic failure - inefficient filling with blood e.g. caused by hypertension, pericarditis, ventricular hypertrophy and fibrosis
Both of these affect CO as SV decreases so CO decreases. (CO = SV x HR).
Can get Left sided heart failure or Right sided heart failure
What are the symptoms of heart failure?
Fatigue
Dyspnoea
Exercise intolerance
Pulmonary oedema (left sided heart failure)
Peripheral oedema (right sided heart failure)
What are the different causes of heart failure?
- Coronary artery disease, myocardial infarction - atherosclerotic plaques form in coronary arteries and this occludes them and there’s a risk of rupturing plaque
- Hypertension - the heart must exert more effort as it’s difficult to move blood in the arteries so can result in myocardium hypertrophy and fibrosis
- Faulty heart valves - could be due to congenital, rheumatic fever or stenosis. E.g. arterial valve stenosis can lead to the left ventricle needing to work harder to make blood flow through the narrowed valve and so left ventricular hypertrophy can occur.
- Delayed cardiomyopathy - due to alcoholism, infection, recreational drugs and adverse affect of drugs.
- Arrhythmia - heart beating too fast can result in ventricles not being filled fast enough. Ventricular arrhythmia can result in sudden death.
How is heart failure treated?
Lifestyle changes, medications and surgery.
Lifestyle changes:
- Increase in aerobic exercise and resistance training
- Decrease in alcohol consumption
- Smoking cessation
- Immunisations
Medications:
- First line given diuretics and ACE inhibitors or Angiotensin II receptor antagonist.
- Also may be prescribed degoxin, spironolactone (aldesterone antagonist), and beta-blocker.
- Watch out as the more meds you prescribe the worse it can get.
- In acute heart failure, IV meds can be given to support circulating volume and maintain BP.
Surgery:
- Coronary Artery Bypass Graft - for coronary artery disease (atherosclerosis)
- Heart valve repair or replacement
- ICD - Implantable Cardiac Defibrillator
What oral healthcare needs may a patient with heart failure have?
Access, may find it difficult to lay down if they have pulmonary oedema.
May be on anti-platelets or anti-coagulants.
Medical care may take priority over oral healthcare.
Consider whether prophylatic antibiotics need to be given for infective endocarditis. Consult cardiologist if required.
What are the four arterial diseases you need to know about? Describe them in detail.
Peripheral arterial disease. Caused by atherosclerosis in large arteries. Stenosis, thrombus formation and plaques can occur at site of embolus and results in ischaemia - chronic and acute. PAD typically affects lower limbs. Initially results in ulcers on lateral borders of the foot but can get gangrene and amputation.
Aneurysm. Dilatation of blood vessel which is filled with blood, due to thinning or damage to vessel wall.
Major type is abdominal aortic aneurysm where aorta goes from 2cm - 10cm. Is asymptomatic but if dissection occurs, 80% of patients die.
Carotid artery stenosis. Atherosclerosis in carotid arteries, can be at the bifurcation which can be picked up on OPT.
To prevent secondary complications, modify lifestyle (smoking cessation, reduce hypertension etc).
Revascularisation can occur through vascular grafts and endarterectomy.
Coronary artery disease.
Define coronary artery disease
A disease which produces ischaemia to the myocardium. May be due to atherosclerosis. Can lead to angina or myocardial infarction.
What are the risk factors for coronary artery disease?
- Hyperlipidaemia - low HDL and high LDL.
- Smoking of tobacco
- Hypertension
- DM
When is it stable angina and what are the causes of stable angina, effects and management of it?
If atherosclerosis forms its plaques at an end artery but it’s not occluding the vessel a lot, this is a stable angina. When at times of exertion (physical stress, emotional upset), then the requirements are increased and it may struggle to get enough blood flow to the heart. This can result in pain (a chest pain that radiates to mandible, left arm, and neck). It also results in sweating, dyspnoea, dizziness.
It can be relieved with the use of short acting nitrates (GTN) and rest.
Patients may also be on beta-blockers/calcium channel blockers, GTN and anti-platelet.
Or they could be on potassium channel activators and long acting nitrates.
What is unstable angina and how is it caused?
What can it lead to?
When the plaque is larger, it can form fissures. Around the site of this fissure, a thrombus can form, which occludes the lumen of the vessel. Insufficient blood can reach the myocardium which results in more angina effects.
If thrombus forms an emboli, this can cause angina effects.
If the thrombus lodges into an end artery, this can cause myocardial infarction as the heart doesn’t receive enough oxygenation.
What is ACS?
When a plaque becomes enlarged, ruptures or becomes thrombosed, this is ACS. Can include unstable angina and myocardial infarction.
Define myocardial infarction, how it is diagnosed, and what can be used in its management.
Myocardial infarction - death of myocardium due to critically insufficient blood flow. This is due to an atherosclerotic plaque rupture.
How it’s diagnosed:
- Elevated ST levels on ECG.
- Elevated troponin levels when cardiac enzyme levels are checked.
How it’s managed:
- Anti-platelet: aspirin
- Analgesia: morphine
- Anti-coagulant: tinzaparine
- Thrombolysis: streptokinase
What are the oral healthcare needs in those with arterial disease?
- Check ASA score
- Reduce triggers for stable angina (aspirate, no stress or fear)
- Effect of risk factors on dental health (smoking, adverse drug effects).
Don’t do any routine dental procedures for 6 months after MI as an arrhythmia can occur, stressful situations can cause catecholamine release, and heart tissue needs to remodel.
