CAD and Angina Flashcards
What factors affect the cardiac workload, and increases cardiac oxygen demand?
Increased heart rate
Increase force of contractility
Increased pre load
Increased afterload
What factor decreases cardiac oxygen supply?
Decreased coronary blood flow
What are the first line anti- anginal drugs
Organic nitrates- Nitroglycerin, isorbide mononitrate
beta blockers, atenolol, bisoprolol, carvedilol, metoprolol
Calcium channel blockers, Dilitiazem, verapamil, Amlodipine, Felodipine, Nicardipine
HCN4 Ion channel blocker, Ivabradine
Which medication is commonly used as a vasodilator in the treatment of variant angina?
a) Isosorbide dinitrate
b) Diltiazem
c) Nitroglycerin
d) Verapamil
Answer: c) Nitroglycerin
Which medication class is commonly used in the management of stable angina by reducing myocardial oxygen demand through negative inotropic and chronotropic effects?
Answer:
a) Nitrates
b) Beta-blockers
c) Calcium channel blockers
d) Angiotensin-converting enzyme (ACE) inhibitors
b) Beta-blockers
Which medication is a potent vasodilator that primarily acts on arterial smooth muscle and is commonly used in the treatment of stable angina?
a) Isosorbide mononitrate
b) Ranolazine
c) Amlodipine
d) Verapamil
Answer: c) Amlodipine
How do calcium channel blockers exert their antianginal effects?
Calcium channel blockers inhibit the influx of calcium ions into vascular smooth muscle cells and myocardial cells, leading to vasodilation of coronary and peripheral arteries, decreased myocardial contractility, and reduced myocardial oxygen demand.
Explain the concept of preload reduction in the management of angina.
Preload reduction refers to the decrease in ventricular filling pressure and volume, which reduces the workload on the heart during diastole. Medications such as nitrates and diuretics can reduce preload by promoting venous dilation and decreasing blood volume, respectively, thereby reducing myocardial oxygen demand.
How do beta-blockers exert their antianginal effects?
Beta-blockers primarily work by blocking beta-adrenergic receptors in the heart, leading to a reduction in heart rate, myocardial contractility, and cardiac output. By decreasing myocardial oxygen demand and improving coronary blood flow, beta-blockers are effective in the management of angina.
MOA of Organic nitrates
Organic nitrates are pro-drugs and are converted into nitric oxide (NO) in vascular
smooth muscle cells (VSMCs). NO then activates guanylate cyclase, which converts GTP (guanosine triphosphate)
into cyclic GMP (cyclic guanosine monophosphate). Cyclic GMP then activates protein kinase G (PKG), which
ultimately causes the VSMCs in blood vessels to relax and induce vasodilation.
3 function of GTNs
Works on collateral coronary arteries–> vasodilation– redistribute and increase blood flow–> ischemic cardiac tissue.
Causes vasodilation of veins and arterioles, to cause a decrease in venous pressure and decrease in TPR(artery) then decrease preload and afterload–> decreasing cardiac workload and cardiac o2 demand.
Contraindications of GTN
Low SBP, Increased cranial pressure, Patients on PDE5 (viagra)
contraindication of CCB
Patients with Heart Failure
Patients on β-Blockers: AV Heart Block
MOA of CCB
1.
Arterioles+
(VSMCs)
VSMCs decrease ca,
Relax Vasodilation ↓TPR ↓MAP
2. Heart–> decrease Ca –> decrease HR, and contractile force–> increase period of diastole and increase in cornary artery opening time–> increase blood flow to ischaemic tissue
Decrease cardiac workload and decrease cardiac o2 demand.
Side effects of CCB
1). Hypotension → Dizziness
2). Reflex Tachycardia (↑HR): Due to Aortic Arch and Carotid Sinus Baroreceptors detecting a decrease in blood pressure.
3). Headache
4). Flushing
5). Constipation: Due to decreased contraction of smooth muscle in the gastrointestinal system. Therefore, decreases digestion.
6). Peripheral Oedema: Due to Dilation of arterioles & No Dilation of Venules/Veins → Build-up of blood in capillaries → ↑
Hydrostatic Pressure in Capillaries → Water leaks into the interstitial compartment of the tissue.
side effect of beta blockers
1). Hypotension → Dizziness and Fainting
2). Bradycardia
3). Atrioventricular (AV) Heart Block: This is where the electrical signal is blocked from the AV node to the Ventricles.
4). Fatigue
5)Bronchoconstriction: May block β2-adrenoreceptors in the airways
6). Hypoglycemia: May block β2- adrenoreceptors in the liver → inhibit glycogenolysis.
7). Cold Extremities (i.e. Hands and Feet)
8). Impotence
Side effects of GTN
Develop Tolerance (body no longer respond to organic nitrates): Due to repeated or continuous exposure to high doses of
organic nitrates. Solution: Use low doses and stop treatment for 8-12 hours daily at night when the patient is usually inactive.
2). Orthostatic (Postural) Hypotension when standing.
3). Reflex Tachycardia: Due to Carotid Sinus & Aortic Arch Baroreceptors detecting a decrease in blood pressure.
4). Dizziness → Syncope (i.e. Fainting)
5). Migraine-Like Headaches: Due to dilation of meningeal artery.
MOA of ivabradine
HCN4 Channel Blocker- blocks the HCN4 ion channel in the Sino-Atrial (SA) node of the heart.
How it functions: ivabradine
Heart SA node–> decrease in generation of pacemaker current–> decrease rate of SA node depolarising–> decrease HR–> decrease cardiac workload and decrease o2 demand.
ALso increases period of diastole –> increase coronary artery opening
Side effects of Ivabradine
Luminous Phenomena (Enhanced Vision Brightness): Due to blocking HCN ion channels in the retina as well.
Bradycardia (Decreased Heart Rate; <60 beats/min)
Atrioventricular (AV) Heart Block: This is where the electrical signal is blocked from the AV node to the Ventricles.
Blurred Vision
Headaches
Dizziness
Hypotension
Fatigue
Contraindications of ivabradine
1). Sick Sinus Syndrome: Due to Sinus Node Defects
2). Patients on Ca2+ Channel Blockers (i.e. Verapamil & Diltiazem) = AV Heart Block
3)Patients on CYP3A4 inhibitors, Azole Antifungals (Ketocanozole), Macrolide Antibiotics, Anti-Retrovirals
Contraindications of Beta blockers
Asthma
Diabetes
Patient on Calcium Channel Blockers
