Cardiovascular Therapeutics Flashcards
What is typically prescribed for chronic heart failure?
ACEIs, diuretics, β blockers
digoxin?
What is typically prescribed for hypertension?
ACEIs, calcium channel inhibitors
Give two examples of ischaemic heart disease
Angina
MI
What to prescribe for LV dysfunction when there are persistent symptoms after use of ACEI/β blockers?
cough - ATRA
aldosterone antagonist or hydralazine plus nitrate
What to prescribe for LV dysfunction when there are persistent symptoms after use of aldosterone antagonist/hydralazine plus nitrate?
AF - digoxin
sinus - ivabradine
What is IHD an important cause of?
How?
congestive heart failure
MI - destroyed part of the heart
or change in ischaemia decreases function of myocytes
What causes IHD?
associated with atherosclerosis within coronary artery - impaired blood flow or thromboembolic occlusion
coronary blood flow does not match demand of the muscle
When do symptoms begin to occur?
stenosis of the coronary artery due to atheroma
Risk factors of IHD
male (female hormones protect) family history (<55 m, <65 f) smoking diabetes hypercholesterolaemia - high LDL:HDL hypertension sedentary lifestyle obesity dental hygiene
Major varities of angina
stable
unstable
What is stable angina?
atherosclerotic disease which limits heart’s ability to respond to increased demand
symptoms on exertion, relieved by rest
What is unstable angina?
plaque rupture and the formation of a non-occlusive thromboembolism OR vasospasm
symptoms at rest
How to diagnose stable angina?
History - chest pains on exertion
stable angina: pain induced by exercise and relieved by rest
GTN - nitrate spray, rapid relief
ECG - ST segment depression - below baseline
Angiography of coronary arteries - catheter, squirt radioactive dye
Management of stable angina
lifestyle - stop smoking, exercise, diet (fruit, veg, oily fish), weight
coronary artery bypass grafting
angioplasty and stenting
What is PTCA
percutaneous transluminal coronary angioplasty
treatment for IHD
Procedure for PTCA
catheter into coronary artery, while taking x-rays
inflate balloon to open vessels
stent inserted, some have drug eluting chemicals which inhibit vascular growth
What are ps undergoing PTCA given beforehand?
and why?
anti-platelets and heparin
inflation of balloon is thrombogenic - prevent further coagulation
Pharmalogical management of stable angina
nitrates - glyceryl trinitrate (GTN) via release of NO, spray under the tongue - rapid relief causes venodilatation (main point) and coronary vasodilatation
What happens if angioplasty occurs without a stent?
restenosis - blocked again by more plaque due to damage to the blood vessel and therefore further coagulation
What does venodilatation do?
decreases preload and reduces cardiac work
Action of GTN
glyceryl trinitrate donates NO into circulation
activates guanylyl cyclase and leads to release of cGMP, causes venodilatation
What type of nitrates can cause problematic nitrate tolerance?
oral nitrates
How to prevent nitrate tolerance?
aim for nitrate free period
2 doses, rather than 3 per day eg. at night
What is the first choice drug for prevention against IHD?
β-blocker - atenolol
How is atenolol anti-anginal? Why does this work?
negative inotropic and chronotropic effects
coronary flow is only during diastole, so slowing the heart will increase diastolic period, including the time for coronary blood flow
therefore it reduces cardiac work and prevents symptoms
How does atenolol reduce the risk of MI?
anti-arrhythmic effects reduce risk of MI
What dose of atenolol is used for angina?
high dose atenolol
Problems of atenolol
p with angina can develop chronic heart failure which is worsened by high dose atenolol - reduces contractility (-ve inotrope)
therefore use bisoprolol
Alternative to beta blockers
calcium channel blockers
eg. amlodipine
Types of calcium channel blockers
rate limiting agents (diltiazem and verapamil)
dihydropyridines (amlodipine)
Rate limiting agents specific action
block calcium channels on heart and smooth muscle - myocardial depressant and bradycardic actions, reduce cardiac work verapamil - also exerts class IV anti-arrhythmic activity
Dihydropyridines specific action
act just on smooth muscle
Effect of calcium channel blockers
vasodilatation, improve coronary blood flow
prevents symptoms
What are calcium channel blockers used for?
IHD
AF
Advantages and disadvantages of rate limiting agents
does not cause reflex tachycardia
but worsens heart failure
What else may ps with IHD be prescribed?
ACEIs
potassium channel activators - nicorandil
Ivabradine
antiplatelet drugs - low dose aspirin and clopidogrel
statins
How does nicorandil work?
combined NO donor and activator of ATP-sensitive K channels
causes hyperpolarisation and vasodilatation
How does ivabradine work?
inhibits funny current channels (pacemaker current in SAN)
reduces heart rate
How do statins work?
prevents synthesis of cholesterol
HMG-CoA reductase inhibitors (first step of synthesis)
therefore causes secondary response: up-regulation of hepatic LDL receptors - promotes LDL uptake
Example of statin
atorvastatin
Problems of statins
rarely causes muscle damage
interactions with macrolides (blocks metabolism of simvastatin), grapefruit juice and some calcium channel blockers - interact, use lower dose statin
When are statins used?
primary prevention - risk
secondary prevention - already exhibited problem
Steps of managing stable angina
GTN
assess CV risk - aspirin/clopidogrel, statin, lifestyle, BP, ACEI
prevention - beta/calcium channel blocker +/- oral nitrate
refractory - dihydropyrimidine, (nicorandil, ivabradine)
What combination is fatal?
rate-limiting CCB and beta-blocker causes asystole (death)
