Lectures 18-19: Stable CAD Flashcards by Claire Mann

Course of ischemic heart disease

Asymptomatic ischemia -> angina pectoris -> unstable angina -> myocardial infarction

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Coronary flow occurs during…Minimum pressure?

Diastole; 60-65 mm Hg

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What are two conditions that could lower diastolic pressure?

Hypotension or aortic regurgitation

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Generally we don’t change pressure, but rather…

Resistance

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What mediates vascular tone? (three classes)

Metabolic factors: adenosine*, acetate, hydrogen ions, CO2; Neural factors: NE –> alpha and beta receptors; Endothelium factors

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Endothelial vasodilators and vasoconstriction. What dominates?

ACh, 5-HT, shear stress –> NO; thrombin, AII, Epi; healthy state = vasodilation, disease state = vasoconstriction

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What can cause increased wall stress? How is this related to CAD?

Pressure/volume overload –> myocyte hypertrophy to normalize wall stress –> increased O2 demand of cardiac tissues

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Besides enlarged myoctyes, what else can increase myocardial oxygen demand? (2)

Increased HR and contractility

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Relationship between atherosclerotic plaques and CAD?

Reduce diameter of coronary arteries –> increased resistance

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What is more important for increased resistance due to plaques…length of lesion or reduced diameter?

Reduced diameter (r^4)

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What is the function of the coronary microvasculature? What happens in disease?

Modulates vasomotor tone; in disease, endothelium is impaired and vasodilation in response to needs does not occur

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At rest, what level of stenosis is required for ischemia? How about exertion? What angina’s are associated with this? Why are these numbers so high?

~90% (unstable angina); ~70% (stable angina); flow is augmented by microvasculature

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What are four ways that endothelial cell dysfunction can occur?

Release of endothelium-dependent vasodilators (prostacyclin/NO) may be impaired in response to normal stimuli (shear stress); Vasodilatory effects of local metabolites also blunted (i.e. adenosine); Vasoconstricting effects of catecholamines predominates; Loss of antithrombotic effect of endothelial cells in response to stimuli (ADP, serotonin, thromboxane) –> small thrombi

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Two classes of non-atherosclerotic causes of ischemia and examples

Reduced O2 supply (aortic regurge, bleeding); Increased O2 demand (tachyarrhythmias, hypertensive crisis, severe aortic stenosis)

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Impacts of ischemia (3)

Myocyte necrosis; stunned myocardium; hibernating myocardium

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What is stunned myocardium

Transient systolic dysfunction after ischemic insult

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What is hibernating myocardium

Chronic ventricular dysfunction due to multivessel CAD w/ reduced blood supply; revascularization treats this

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Define stable angina

Retrosternal chest discomfort precipitated by exertion

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Define unstable angina

New-onset severe angina or increased severity/frequency of stable symptoms

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Define variant angina

Episodes of coronary spasm reduces O2 supply, occurs at rest

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Define syndrome X. Treatment?

Chest pain but normal coronary arteries, due to microvasculature dysfunction; medically: cannot be treated surgically

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Define silent ischemia. Treatment?

Ischemia w/out clinical symptoms; not sure if we should treat, currently addressed with ISCHEMIA trial

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Stable angina: sensation

Pressure, tightness, heaviness, burning

Stable angina: duration

Few minutes

Stable angina: location

Diffuse, not focal

Stable angina: associated sxs

SOB, fatigue, nausea

Stable angina: precipitants

Exertion and emotional stress

Stable angina: frequency

Distinguishes from unstable

Systems on differential dx

Cardiac (spasm, pericarditis), GI, MSK

Stable angina: ECG

Typically normal, not of high value

What is one way to dx chronic stable angina?

Stress testing: make them exercise and then detect ischemia (ECG, echo, nuclear perfusion imaging)

Describe coronary angiography

Invasive procedure requiring contrast media for direct visualization of stenotic lesions; gold standard in dx of CAD

Describe nitrates: use, mechanism

Treatment of stable CAD; cause venodilation --> reduce LV volume --> reduce wall stress --> decrease mycoardial O2 demand

Side effects of nitrates

Lightheadedness, headache

T/F: Nitrates improve long-term survival

False

Describe beta-blockers use for stable CAD

Reduce mycardial O2 demand by decreasing HR and contractility

Side effects of beta-blockers (3)

Bronchospasm, bradycardia, impotence

T/F: Beta-blockers improve long-term survival

True

If a patient has had a prior MI, what do you give them?

Beta-blocker! Can extend life

DON'T give beta-blockers to these three groups

Patients in shock, patients with airway disease, diabetics (may mask reflexive tachycadia from hypoglycemia)

Ca2+ Channel Blockers...groups and effects

Dihydropyridines: vasodilating >> cardiac depression; nondihydropyridines: cadiac depressant >> vasodilating

Once again, vasodilating improves CAD how?

Decreases myocardial O2 demand by reducing wall stress

Should you combine Ca2+ blockers and beta-blockers?

NOPE: accentuate negative chronotropy/inotropy --> major bradycardia

What is ranolazine?

New drug to treat angina w/ unclear molecular mechanism

What does aspirin do?

Reduce risk of thrombotic complications by inhibition of platelet aggregation

What is another antiplatelet therapy?

Thienopyridine (Clopidogrel): inhibits platelet receptor

Why do we give a lipid lowering therapy? Quantity or quality of life? When do you give?

Lowers risk of death in patients at risk with established CAD (quantity); administer statin to patients with >7.5% risk of MI in 10 years

Why would ACE inhibitors be helpful for CAD?

Reduce cardiac events

Medical therapy for stable CAD (summary)

Quality: nitrate, beta-blocker, CCB, ranolazine; Quantity: aspirin, statin, beta-blocker, ACE-I

Two revascularization options

Stenting and coronary artery bypass grafting

What is a drug-eluting stent?

Stents coated with antiproliferative agent to inhibit restenosis but delays endothelializaion --> increased risk for thrombosis

Two types of grafts

Venous and arterial (very high patency)

What is the preferred strategy for complex patients (multivessel disease, left-main, diabetic)

Coronary artery bypass grafting

Advantages/disadvantages of PCI

Advantages: low procedural risk, minimal recuperation; Disadvantages: need dual antiplatelet therapy, higher rates of revascularization

Advantages/disadvantages of CABG

Advantages: complete revascularization, no need for long term DAPT, proven mortality benefit; Disadvantages: higher procedural risks, longer recuperation