Angina Flashcards
Vicious cycle of myocardial ischaemia
Myocardial demand exceeds myocardial oxygen supply
This leads to myocardial ischaemia
The ischaemia causes further vasoconstriction, continuing the cycle
Drug targets for angina
- increase supply: nitrates
- reduce demand: beta blockers
Difference between angina pectoris and myocardial infarction
Pathophysiology of atherosclerosis
Endothelial damage occurs (by whatever means e.g. metabolic stress), this allows lipoprotein to collect in the intima. As the lipoproteins are free from plasma antioxidants they will then become oxidatively modified. Next leukocytes are recruited and finally mononuclear phagocytes differentiate into macrophages and transform into lipid laden foam cells
Definition of angina pectoris
Non ischaemic causes of angina pectoris
Chest discomfort due to myocardial ischaemia associated with coronary artery disease
Other causes: aortic stenosis, hypertrophic obstructive cardiomyopathy
Types of angina
Stable
Unstable
Prinzmetal/variant
Syndrome X
Stable angina
Angina occurring over several weeks without major deterioration, although symptoms may vary considerably over time (eg with extertion, stress)
Unstable angina
Abrutptly worsening angina or new angina at low work load
When plaque goes from being stable to unstable
Prinzmetal angina
Spontaneous (i.e. no precipitating cause) angina with ST elevation on ECG.
Coronary artery spasm, often near the site of plaque formation.
Classic symptom: chest pain at night
Syndrome X
Happens in perimenopausal or menopausal women.
Angina with objective evidence of myocardial ischaemia (eg ST depression) in the absence of evident coronary atherosclerosis or epicardial (large vessel) disease
Triad:
- Anginal chest pain
- Positive exercise test on treadmill
- Angiographically smooth coronary arteries
Doesn’t often respond to classic anti-anginal therapy
ECG findings in prinzmetal’s angina
Profound ST elevation
Key to diagnosis of prinzmetal’s angina
Chest pain when going to bed
Decubitus angina
Comes on when patient is lying in bed.
Due to severe coronary artery stenosis.
Physiology:
- increased venous return when lying down
- increased myocardial work
-
Characteristics of the pain
Site- typical angina is central
Character- dull ache is typical. Sometimes it’s not “pain”, it’s “squeezing”
Mode of onset- sudden (likely to be MSK) vs gradual (likely to be cardiac)
Progression
Radiation- often goes to the neck and arm
Positional body function- if its worse upon neck movement for eg we know its MSK
Precipitating or relieving factors- whether activity makes it worse?
Treatment eg GTN BUT BEWARE, because GI reflux also causes chest pain and GTN relaxes lower end of oesophagus (confounding!)
Other chest pains
MI: sudden, severe, SWEATING
Aortic dissection: tearing pain- abdo or back. Suspect in relatively eldelry patients.
Pericarditis- usually viral aetiology. Sharp, sudden chest pain. Worse upon breathing, postural differences. Can usually hear a pericardial RUB
Investigations for angina
Blood pressure
Lipids
ECG- resting is usually normal in CHD. May pick up old infarct (Q waves).
Stress test- look for ST segment depression.
Angiography- if you already suspect it and want to assess the severity. Usually in patients who’ve had an MI and want to assess
What measurement is used to classify the relationship between exercise capacity and post-MI mortality?
Bruce score.
Bruce score <10 mis=9% mortality
Bruce score >10 mins= 2 % mortality
What finding on the ECG in a stress test would indicate CHD?
ST depression > 1mm
What finding on ECG would indicate previous MI?
Q waves (Q waves that are longer than normal)
When to stop an exercise test?
- severe chest pain
- rapidly dropping ST segment
- drop in blood pressure (shows reduction in cardiac output)
- arrhythmias (Detected on ECG)
What is the cause of death of cardiac myocytes in myocardial infarction?
- lack of oxygen
- cessation of sodium-potassium ATPase
- cells fill up with sodium
- water comes in so cells swell and die
What is the blood pressure like in aortic stenosis?
LOW blood pressure
Male vs female incidence of hypertrophic obstructive cardiomyopathy
Equal sex ratio
Overview of angina management
- education/lifestyle- exercise
- anti-anginal drugs
- anti-platelet drugs- avoids complications
- revascularisation therapy- CABG or PCI
Reasons for supply and demand problems in angina
Low supply
- coronary insufficiency- vasospasm or stenosis
- Outflow obstruction- aortic stenosis or hypertrophic cardiomyopathy
- anaemia
High demand
- arrythmias (AF), sinus tachycardia
- thyrotoxicosis
- high afterload (systemic hypertension)
-
Anti-anginal drugs
FIrst line therapy for angina
Beta blockers- because of prognostic benefit eg post-MI and hypertensives
Beta blocker contraindications
Erectile dysfunction
2 main categories of CCBs
Which 3 drugs are often used synergistically for angina?
Beta blockers
CCBs
Nitrates- relax vascular smooth muscle, improving blood supply to the heart
Calcium antagonists
- used with or instead of beta-blockers
- heart: negatively inotropic. Blood vessels: peripheral vasodilation
- amlodipine is more vasoselective than nifedipine, so has less of a -ve inotropic effect- preferred
- diltiazam and verapamil are also NEGATIVE CHRONOTROPES
- the non-DHPs are particualrly useful for vasospastic angina
- short-acting DHPs may increase adverse cardiac events
Contraindications and side-effects of CCBs
Nitrates
Side effects and ocntraindications of nitrates
Nicorandril
MOst useful when there are contraindications to CCBs o BB
What shold all patients with variable angina be on?
ANTI-PLATELET THERAPY
How is coronary angiogram carried out?
Tube inserted from artery in groin- goes towards coronary arteries, which are X-rayed with a dye inserted.
Benefits of PTCA (percutaneous transluminal angioplasty)?
- Chronic stable angina: no benefits on longevity.
- MI: beneficial.
With chornic stable angina main treatment is drugs and exercise.
Schematic of angioplasty
- first they carry out coronary angiogram to find out where the blockage is
- insert a balloon, which is inflated and pushes the narrowing out towards the wall
- SOMETIMES they put a stent in along with it to HOLD the widened part open
What is revascularization?
Two methods: CABG OR PCI
PCI: percutaneous intervention.. Includes coronary angioplasty ALONG WITH STENT insertion.
