Cardiology - Ischaemic Heart Disease Flashcards
Fractional Flow Reserve
- how is it done?
- Cut-offs?
Adenosine is used to induce maximal hyperaemia
= gold standard for VESSEL SPECIFIC ISCHAEMIA
FFR <0.8 = ISCHAEMIA
Fractional Flow Reserve: benefit when used during PCI
In multivessel disease during PCI it reduced MI and death
In the pathogenesis of atherosclerosis:
Which apolipoprotein combines with LDL, where and what do they do?
LDL combines with Apolipoprotein B in the INTIMA and binds to extracellular matrix
In the pathogenesis of atherosclerosis:
What are foam cells?
Foam cells develop when MONOCYTES take up lipoprotein particles by endocytosis
In the pathogenesis of atherosclerosis:
How is cholesterol transferred from cell to HDL?
via the ABC (ATP Binding Cassette) transporters
ABC-A1 gene transfers to nascent HDL (mutated in Tangier’s with VERY LOW HDL)
ABC-G1 gene transfers to mature HDL
In the pathogenesis of atherosclerosis:
Role of ABC-A1 gene?
Transfers cholesterol from cell to nascent HDL
mutated in Tangier’s with VERY LOW HDL
In the pathogenesis of atherosclerosis:
Role of ABC-G1 gene?
Transfers cholesterol from cell to mature HDL
Which ABC gene transfers cholesterol from cell to NASCENT HDL?
ABC-A1
Which ABC gene transfers cholesterol from cell to MATURE HDL?
ABC-G1
What is mutated in Tangier’s?
ABC-A1 gene resulting in VERY LOW HDL
What does HDL do with the cholesterol it picks up?
HDL delivers cholesterol to hepatocytes via Scavenger Receptor B1
What produces PDGF?
And what does PDGF do in the pathogenesis of atherosclerosis?
PDGF = Platelet Derived Growth Factor
It is produced by activated platelets, macrophages and endothelial cells.
It stimulates smooth muscle cells in tunica media to migrate to intima
In the pathogenesis of atherosclerosis:
What does TGF-beta do?
Stimulates smooth muscle cells to make collagen
In the pathogenesis of atherosclerosis:
What makes plaques prone to rupture?
- thin fibrous caps
- large lipid cores
- high macrophage content
- outward remodelling
- spotty calcification rather than dense
Which coronary arteries are typically effected in stable angina?
Stable angina is usually angina secondary to atherosclerosis of EPICARDIAL arteries
What is microvascular angina?
Angina with no flow-limiting obstruction in the epicardial arteries
Is microvascular angina more common in males or females?
Females
How do you diagnose microvascular angina?
Coronary reactivity tests with vasoactive agents: ie:
- intracoronary adenosine
- intracoronary acetylcholine
- intracoronary nitroglycerides
How do you manage microvascular angina?
Nitrates
Betablockers
CCBs
Statins
Who do you see ABNORMAL CARDIAC NOCICEPTION in, and how do you treat?
Abnormal cardiac nociception is a type of angina with no flow-limiting obstruction in epicardial arteries (LIKE microvascular but NOT)
Seen in FEMALES
Trial treatment with IMIPRAMINE
Link between CRP and Stable Angina?
If the CRP level in stable angina is elevated it is an INDEPENDENT RISK FACTOR
Can help reclassify it as ‘intermediate risk’
ECG features that increase risk of adverse events in STABLE ANGINA?
LVH
When do you use Exercise Stress Test for chest pain?
If intermediate pre-test probability 10 - 90%
How good is Exercise Stress Testing in coronary artery disease?
Sensitivity 80%, Specificity 70%
If POSITIVE and MALE >50yrs with a typical history of pain IN THE TEST then likelihood of CAD is 98%
What is Exercise Stress Test MOST SENSITIVE for?
Triple vessel disease
What coronary artery might result in a FALSE NEGATIVE on your Exercise Stress Test?
Left Circumflex
Ideal goal when doing an Exercise Stress Test?
To exercise 6 - 12 minutes to achieve 85% of age-predicted max-heart rate (220-age)
What is the DUKE TREADMILL SCORE and what is it based on?
Provides 5yr mortality
Based on:
- development of symptoms
- degree of ST depression
- exercise duration
In the first minute of stopping an Exercise Stress Test, what increases your mortality?
If your heart rate recovery is <12bpm in the first minute then INCREASED mortality
What meets criteria for a positive Exercise Stress Test?
>3mm ST depression >2mm ST elevation SBP >230mmHg Fall of SBP >20mmHg HR DECREASES >20% of starting rate Arrythmia
Contraindications to an Exercise Stress Test?
- Aortic Stenosis
- LBBB
- MI <7 days ago
- Rest angina <48 hours ago
- Uncontrolled BP
Problem with WOMEN doing an Exercise Stress Test?
Women have a high rate of FALSE POSITIVES
BUT if the woman is LOW RISK then the Exercise Stress Test is similar to a nuclear med myocardial perfusion scan
Risk of doing an Exercise Stress Test?
1 in 10,000 mortality
1 in 10,000 non-fatal events
Is an stress echo or exercise stress test more sensitive?
A stress echo is more sensitive because it assesses if stress causes regions of AKINESIS or DYSKINESIS
In nuclear stress tests what is used to stress the heart?
How do they work?
DOBUTAMINE: increases myocardial oxygen demand
ADENOSINE or DIPYRIDAMOLE:
Temporarily increases flow in nondiseases segments to cause flow disparity
Which medication used in nuclear stress tests increases myocardial oxygen demand?
Dobutamine
Which medication used in nuclear stress tests temporarily increases flow in nondiseases segments to cause flow disparity
Adenosine or Dipyridamole
What classifies a MARKEDLY POSITIVE nuclear exercise test?
Lung uptake of thallium
Ischaemia in >2 vascular territories
EF <35%
What classifies as MARKEDLY POSITIVE exercise echo?
EF <35% at rest
Fall in EF with stress
Ischaemia in >2 vascular territories
The severity of coronary artery narrowing WHERE is associated with a higher risk in stable angina?
Left main
LAD proximal to origin of first septal artery
In treating STABLE ANGINA:
Should you use a statin?
YES!
- stabilises plaque
- Reduces risk of MI and death (25 - 30%)
- reduces LDL (25 - 30%)
- reduces TGAs (5 - 30%)
- INCREASES HDL (5-9%)
How do nitrates work?
Relax vascular smooth muscle by releasing NITRIC OXIDE that binds to GUANYLYL CYCLASE in smooth muscle and INCREASES cGMP
Results in:
- systemic venodilation with reduced LV EDV and pressure
- increased collateral flow
- dilation of epicardial vessels
What do nitrates result in?
Increases Exercise TOLERANCE
but NOT mortality benefit
Effect of nitrates on bleeding?
Antithrombotic effect
Because NO-dependent activation of platelet guanylyl-cyclase, impaired intraplatelet calcium flux and platelet activation
Which five medication classes work as anti-anginals? (excluding perhexiline)
Nitrates Betablockers CCBs (nondihydropyridine) Ranolazine Nicorandil
Which calcium channel blockers can you use for their anti-anginal effect?
Non-dihydropyridine CCBs: verapamil and diltiazem
How does ranolazine work as an antianginal?
Selective inhibitor of late inward sodium channel in myocardium
–> prevents calcium overload via Na/Ca exchange
When is ranolazine contraindicated?
- hepatic impairment
- QTc prolongation
- use with CYP3A4 inhibitors
How does nicorandil work as an antianginal?
Opens ATP-sensitive K channels in myocyte to cause reduction of free intracellular calcium
When do you revascularise in stable angina?
If symptoms persist despite medical treatment
At which SYNTAX SCORE is coronary artery disease considered severe?
> 22
Benefit of PCI in treatment of stable angina?
More effective for RELIEF
BUT
No better than medical treatment for mortality or MI
How many BMS have restenosis in 6 months?
20%
How many DES have restenosis in 6 months?
<10%
What increases your risk of restenosis after revascularisation?
- diabetes
- small arteries or incomplete dilation
- longer stent
When do we use CABG in preference to stenting in coronary artery disease?
- left main disease
- three vessel disease
- LV dysfunction
- diabetes IF MULTI-VESSEL
Benefit and Risks of CABG compared to stenting?
Benefit:
- mortality <1%
- occlusion much lower, with 10-20% in 1st year and <2% per year afterwards
Bad:
- recurrence of angina in 25% by 3 years
- higher stroke risk than PCI
