Angina Flashcards
Define angina
Chronic/acute ischaemic heart disease associated with transient chest discomfort/pain due to reduced blood flow to heart
Angina is characterised by reversible/irreversible mismatch between myocardial O2 supply & demand
reversible
List the 3 types of angina
Classic angina
Variant angina
Microvascular angina
Describe classic angina and its effect on myocardial O2
Atherosclerotic plaque partially obstructs coronary arteries, so myocardial O2 demand increases and the supply cannot match it
When does classic angina normally occur
Exercise/stress induced
Describe variant angina and its effect on myocardial O2 supply
Spasm of coronary arteries due to a decrease in myocardial O2 supply
When does variant angina normally occur?
Rest/asleep
Describe microvascular angina
Primary dysfunction of small coronary arteries due to a functional/structural defect resulting in chest pain at rest or on exertion
Name the 2 clinical subtypes of angina
Angina with obstructive CAD
Angina without obstructive CAD
Describe the features of angina with obstructive CAD
- effort induced, chest pain on exertion
- fixed obstructive CAD = atherosclerotic plaque
- ST-segment DEPRESSION
Describe the features of angina without obstructive CAD
- pain at rest/night
- spontaneous coronary artery spasm
- ST-segment ELEVATION
- Arrhythmias
- Variant angina - angiospastic
- microvascular angina - syndrome X
What is the result of a positive stress test for microvascular angina during exercise
ST-segment depression
List the 3 clinical features of angina
haemodynamic
metabolic
electrocardiographic
State why angina causes breathlessness & dizziness
Due to ischaemia-induced transient LV dysfunction
Describe the metabolic effects of angina
Increased myocardial lactate breakdown & net ATP breakdown due to anaerobic metabolism
What does an ECG machine show for a person with angina
ST-segment depression OR elevation
What is the aim on clinical management of angina?
Control symptoms
Prevent/reduce frequency of anginal episodes
Slow progression
Prolong survival
Describe 3 features of the multi-faceted approach to manage angina
- lifestyle & risk factor modification
- pharmacological therapy for symptomatic control
- myocardial revascularisation
State how does pharmacological/anti-viral drug therapy work to treat angina
Improves myocardial O2 supply and reduces demand
Describe the pharmacological action of nitrates & nitrites
Directly acts on blood vessels by reducing vascular r
tension (vasorelaxation) -> systemic vasodilation ( decreases SVR & increases BF)
Describe the cellular mechanism of vasorelaxation
In vivo conversion to NO
Activation of guanalyte cyclase which increases cGMP
Activation of PKG -> vasorelaxation
Describe the mechanisms of the anti anginal effect of nitrates
- peripheral venodilation decreases preload -> decreases MV O2
- peripheral arterial & arteriolar dilation decreases afterload -> de creases MV O2
- coronary vasodilation reverses & prevents spasm
Describe the process of nitrate action to decrease preload
Peripheral venodilation peripheral pooling of blood decreases venous return decreases ventricular volume & intraventricular pressue decreases CO decreases myocardial O2 demand
List adverse effects of the clinical use of nitrate treatment for angina
- flushing
- headaches (throbbing)
- postural hypotension
- reflex tachycardia
- increases myocardial contractility
Describe the recommendations for nitrate therapy
- begin with a small dose & establish dose threshold
- use the smallest amount possible that gives symptomatic relief
- nitrate interval of 8-10hrs (split doses to 8am & 2pm)
State the indication for the use of B-adrenoceptor antagonists and describe how they work
- angina pectoris e.g. propanolol, atenolol
- Antagonise effects of hormones e.g. noradrenaline & adrenaline at B-adrenceptors
List the 3 subtypes of B-adrenoceptors
- B1-ARS - heart & kidney
- B2-ARS - heart & smooth muscle
- B3-ARS
Name the 2 classes of B-blockers and give an example for each
- non-selective e.g. propanolol
- B1 - selective - cardioselective e.g. atenolol
Describe the classification of b-blockers and give drug examples
- 1st generation
non-selective without vasodilation
e.g. propanolol, timolol - 2nd generation
B1 selective without vasodilation e.g. atenolol, bisoprolol
B1 selective with vasodilation e.g. nebivolol - 3rd generation
non-selective with vasodilation e.g. carvedilol
Describe the mechanism of the anti-anginal heamodynamic effects of B-blockers
decreased myocardial O2 demand
decreases myocardial contractility
decreases HR
decreases system BP
Describe the mechanism of the anti-anginal ancillary effects of B-blockers
increased diastolic filling time -> increases myocardial perfusion
antiarrhythmic activity increases electrical stability
antiatherogenic & antithrombotic
State the clinical use of B-blockers for angina
First line prophylaxis of chronic stable angina
What is the pharmacokinetic difference of B-blockers
Lipid solubility
Give an example of a lipid soluble B-blocker
propanolol
Describe characteristics of lipid soluble B-blockers
- eliminated via hepatic metabolism
- completely absorbed from gut
- metabolised in liver
- variable bioavailability
- short plasma life
Describe characteristics of water soluble B-blockers
- eliminated via kidney unchanged
- incompletely absorbed from gut
- less variable bioavailability
- longer plasma life
List the adverse effects of B-blockers
- cold extremities (peripheral vasoconstriction)
- increased LV size -> increased MV O2 demand
- Exacerbation of asthma (bronchospasm)
- risk of HF (myocardial depression)
- aggravation of angina (rebound phenomenon)
- sexual dysfunction - poor patient compliance
- CNS disturbances (nightmares, depression, confusion)
State what CCBs are used to treat
Angina, HPT
Describe the pharmacological action of CCBs
Inhibit entry of Ca into cells via voltage-gated Ca channels
Describe 2 cardiac effects of CCBs
- Block Ca influx into cardiac muscle cells which decreases cardiac contractility
- Block Ca influx into nodal & conducting cells which decreases HR
Describe 3 vascular effect of CCBs
- Block of Ca influx into arterioles -> arteriolar dilation
- peripheral vasodilation decreases SVR & arterial BP
- Coronary dilation increases coronary blood flow & reverses and prevents spasm
Give 2 examples of CCBs used to treat angina
diltiazem
verapamil
Describe the anti anginal effect of reduced myocardial O2 demand
(CCBs)
reduced arterial BP, myocardial contractility & HR
Describe the anti anginal effect that increases myocardial blood flow
(CCBs)
- coronary vasodilation increases coronary blood flow
- spasm reverasl/prevention
State 2 types of angina that CCBs manage
First line for chronic stable angina
variant angina
List 5 secondary prevention options for a patient being diagnosed with angina
aspirin 75mg daily
statin
ACEIs (diabetics)
BP & diabetic control
Name the 4 treatment options for SCAD
Nitrates & nitrites
B-blockers
CCBs
Miscellaneous agents
For patients undergoing nitrate therapy for angina, why should they avoid sustained release formulations?
Longer exposure to nitrates speeds up depletion of thiol groups -> tolerance
Why are oral nitrates not effective
1st pass metabolism reduces bioavailability
Define vasorelaxation
Reduction of vascular tension
State a drug (nitrate) used to relieve acute angina attacks
GTN
amyl nitrite
State a drug (nitrate) used for prophylaxis of chronic angina
GTN
ISMN
ISDN
Name the 3 groups of miscellaneous agents that treat angina
K channel openers
Sinus node inhibitors
Late Na current blockers
Give 1 example of a K channel opener
Nicorandil
Describe the 2 effects of K channel openers
- venodilatation -> decreases preload & MV O2
- arterial dilatation -> decreases afterload & MV O2
Give 1 example of a Sinus node inhibitor
ivabradine
Describe the effect of a Sinus node inhibitor
Inhibition of If -> decreases HR & MV O2
Give 1 example of a late Na current blocker and describe its effect
Ranolazine
Inhibition of I Na -> anti-ischaemic effects
State the 3 treatment options of stable angina
medical
PCI
CABG
State 2 revascularisation procedures
PCI
CABG
Describe what revascularisation does
Restore blood flow to artery to increase myocardial O2 supply
What are 2 methods of PCI
Ballon angioplasty
Coronary stenting
What effect does revascularisation have on myocardial O2 supply and why
increases MV O2 supply due to increased blood flow