Ischaemic Heart disease Flashcards
What is Ischaemic heart disease?
- Angina (angina pectoris) or Myocardial infarction
- Impaired blood flow or thromboembolic occlusion in coronary artery
- Coronary blood flow does not match demand, leading to ischaemia
- (plaque rupturing can cause platelet buildup and lead to a clot)
What are risk factors for IHD?
- Male gender
- Family history
- Smoking–
- Diabetes mellitus–
- Hypercholesterolaemia–
- Hypertension–
- Sedentary lifestyle–
- Obesity–
How to manage Angina pectoris?
Lifestyle:
* Stop smoking
* Excercise
* Diet
* Weight
- Dif types e.g. stable, unstable angina
- Coronary artery bypass grafting
- Percutaneous transluminal coronary angioplasty & stenting
How to pharmacologically manage angina pectoris? (list)
- Nitric Ocide
- Nitrates
- B-adrenoceptor antagonists
- Ca channel blockers
- ACEIs
- Potassium channel activators
- Ivabradine
- Antiplatelet drugs
How does Nitric oxide manage Angina pectoris?
- Synthesised in endothelial cells
- eNOS (endothelial), iNOS (inducible, inv in inflammation), nNOS (neuronal, inv in synth or neuronal NO as neurotransmitter)
- Nitric oxide=vasodilater-acts on guanylate cyclase to make cGMP which causes dilation
How does Nitrate manage Angina pectoris?
- e.g. glyceryl trinitrate (GTN)
- Via release of NO-Nitrates converted to NO by aldehyde dehydrogenase
- Venodilatation(Relaxation of blood vessels) leads to a decrease in preload and a reduction in cardiac work
- Reduce the heart’s requirement for blood
- Also, coronary vasodilatation-more blood flows through the coronary circulation
Explain Nitrate tolerence.
- Prolonged exposure can reduce effectiveness
- Partly due to reduced conversion by aldehyde dehydrogenase
- Inactivation by reactive oxygen species (ROS) e.g. superoxide (O2-)
Side effects:
* Vasodilation also causes headaches-cerebral vasodilatation
* Also-postural hypotension-impaired distribution of blood
How do B-adrenoreceptor Antagonists manage Angina pectoris?
- First choice drugs for prevention
- ↓ HR & ↓Force–> ↓Cardiac work and preventing symptoms
- Slowing HR inc diastolic period, as will the time for coronary blood flow.
- B-adrenoceptors inc K+ channel closing-red the time betw contractions and therefore inc HR
- B-blockers-therefore block this and red HR
- Coronary blood flow occurs during diastole
How do calcium channel blockers manage Angina pectoris?
- Dihydropyridines: Block vasoconstriction so improve coronary blood flow
- Verapamil & diltiazem-effects on HR so reducing Cardiac work
How do ACEIs manage Angina pectoris?
- Vasodilation-reduced workload on the heart
- Reduction in MI and stroke
How do potassium channel activators manage Angina pectoris?
- Nicorandil: combined NO donor and activator of ATP-sensitive K-channels
- The target is the ATP-sensitive K+-channel
How does Ivabradine manage Angina pectoris?
- Inhibits If channels (pacemaker Na/K currents in the SAN)
- HCN channel
- Red HR-by slowing rate of depolarisation
- Ivabradine enters the channel from inside when in open state
How do Antiplatelet drugs manage Angina pectoris?
- Inhibition of platelet aggregation prevents clot formation
- Ensures blood flow through coronary artery
What is a Myocardial infarction?
- Thromoembolism or rupture of plaque
- Thrombus forms in a blood vessel (blocks blood flow), leading to infarction (tissue death due to inadequate blood supply)
What are the symptoms of MI?
- Prolonged cardiac pain-chest, throat, arms, epigastrum or back
- Breathlessness
- Collapse
- Anxiety
- Nausea/vomiting
- May be ‘silent’ MI
