2 - MI, angina & heart failure Flashcards
(25 cards)
what is a myocardial infarction (MI)?
also known as a heart attack
- blockage of 1 or more coronary arteries which results in
death of the affected heart muscle
- major sign is pain, unlike angina this pain can’t be relieved by vasodilators and rest
what happens to the to heart during an MI?
- the blocked artery deprives the heart of oxygen (ischemia)
- injuring the heart muscle, chest pain and may result in irreversible death of heart muscle (infarct)
- plaque build up in artery -> blood clots which blocks artery -> no blood flow
what is an ischemic heart disease?
- heart problems caused by narrowed heart arteries
- imbalance between the myocardial blood flow and the metabolic demand of the myocardium
causes of atherosclerosis?
it is a response to damage of the tunica intima, damage can be caused by:
- bloodborne chemicals
- hypertension
- components of cigarette smoke
- viral or bacterial infections
what are the risk factors of atherosclerosis?
- increasing age
- kidney disease
- lack of exercise
- hypertension
- smoking
- obesity
- family history
- diabetes
- stress
what is an atheroma?
it is degeneration of the walls of the arteries caused by accumulation of fatty deposits
how do atheromas develop?
abnormal accumulation of material in the inner layer of the artery wall
what is coronary atherosclerosis?
it is a build up of plaque in the artery walls, coronary artery lumen must be reduced by 75% or more to cause ischemia (inadequate blood supply to the heart)
what is collateral circulation?
- tiny collateral blood vessels grow when needed
- by the time a coronary artery blockage develops, the multiple collaterals grow to make alternative routes round the blockage creating a “natural bypass”
what is angina?
type of chest pain caused by reduced blood flow to the heart. “choked chest”
what happens during angina?
- myocardial cells are weakened but don’t die
- most common during stress or physical activity when oxygen requirements of the myocardium are not met
what can be done to prevent heart attacks?
- angioplasty which is a surgical repair
- stent, which is a wire frame that helps keep artery open
- coronary artery bypass graft, blocked artery is replaced
How to diagnose an MI or angina
- get pain history
- other signs and symptoms
- taking vitals
- electrocardiogram
- blood test for cardiac enzymes
what is an electrocardiogram (ECG) used for?
- used to diagnose heart attack or ischemic disease like angina
- an MI may be indicated by a raised S-T segment
- confirmation of an MI may involve the presence of cardiac biomarkers
what is a defibrillator and what is it used for?
- electric shock used to correct life threatening heart rhythms
- detects dangerous heart rhythm and applies shock if necessary
- heart restarts
what is heart failure?
the heart is still beating but failing to pump blood to meet the bodies needs
- heart attack is a common cause of heart failure
- however a heart that fails is still beating
- heart failure involves either or both ventricles
what happens during left ventricular heart failure?
the left ventricle is the thickest muscle of the heart an therefore needs the greatest blood supply
- left ventricular failure causes back pressure on the lungs which could lead to pulmonary oedema.
- MI is a common cause of cardiac failure, especially LVF
- LVF often causes RVF
what happens during right ventricular failure?
- Right ventricular failure results in a backup of blood in the venous system
- Blood returning to the right side of the heart comes from systemic circulation and is to be pumped to the lungs
- If there is impaired blood flow It can cause congestion in the pulmonary artery
- Congestion of the pulmonary artery will interfere with right ventricle emptying leading to right sided failure
- Congestion of blood in systemic veins will result in peripheral oedema and system failure
what is the treatment of heart failure and MI?
- Prevention is the best option
- Need to look into risk factors and lifestyle
- Surgery
- Angioplasty
- Medication
- Pain management – important as pain stimulates stress response
What is preload?
- Pressure in the hear when the heart is relaxed
- Preload in the right side of the heart depends on systemic venous return to the heart
- Preload in the left side depends on venous return from the lungs
- When the venous return is decreased the heart muscle will not stretch as much, causing a decrease in cardiac contractibility and cardiac output
What is afterload?
- The forced pressure against which the ventricles must eject blood
- Ventricles increase its force of concentration
- Increased force of concentration will increase oxygen demand of the heart
What is the difference between compensated and decompensated heart failure?
- Initially cardiac failure will be compensated by the renal system & activation of the sympathetic nervous system, resulting in increased heart rate & contractility
- In decompensated heart failure, stroke volume is decreased and peripheral and pulmonary oedema develops
What does left ventricular ejection fraction (LVEF) mean?
- It measures how much blood the left ventricle pumps out with each contraction
- Many patients with heart failure have a normal LVEF (70%) as shown by echocardiography
What is preserved ejection fraction (HFpEF)?
- Diastolic heart failure
- The heart muscles contract normally but the ventricles don’t relax when filling
