Cardiology Flashcards
Mechanism of action of Bisoprolol
Cardioselective beta-1-adrenoceptor antagonist.
Blocks beta-1 receptors in cardiac and renal tissue.
Inhibits sympathetic stimulation of the heart and renal vasculature.
Blockade of the sino-atrial node reduces heart rate (negative chronotropic effect) and blockade of receptors in the myocardium depresses cardiac contractility (negative inotropic effect).
Additionally, blockade of beta-1 adrenoceptors in renal tissue inhibits the release of renin, depressing the vasoconstrictive effects of the renin-angiotensin-aldosterone system.
Name 3 complications of Bisoprolol
Bradycardia Hypotension Bronchospasm Fatigue (Can affect up to 10% of patients) Cold extremities Sleep disturbances
What is the mechanism of action of Propanolol
Non-cardioselective beta-1-adrenoceptor antagonist.
Inhibits sympathetic stimulation in the heart and vascular smooth muscle.
Name 3 indications of Propanolol
Hypertension Angina Anxiety Migraine prophylaxis Post-MI prophylaxis Carvedilol or Bisoprolol may be used as part of supportive therapy for mild / moderate heart failure.
Name 3 side effects of Propanolol
Bradycardia Hypotension Bronchospasm Fatigue (Can affect up to 10% of patients) Cold extremities Sleep disturbances Loss of hypoglycaemic awareness
What are the important pharmacokinetics/pharmacodynamics with Propanolol
Caution in diabetic patients – risk of deranged carbohydrate metabolism
Avoid in patients with Asthma and COPD – risk of bronchospasm
Do not combine Beta-Blockers with rate-limiting Ca2+-Channel-Blockers (Verapamil / Diltiazem) in anti-hypertensive therapy.
Propanolol is lipid-soluble and is predominantly cleared by the liver. Avoid in liver impairment. Avoid abrupt withdrawal – risk of liver impairment.
What type of drug are propanolol, atenolol and bisoprolol
beta blockers
What type of drugs are ramipril, enalapril, perindopril and lisinopril
ACE inhibitors
How do ACE Inhibitors work?
Inhibits conversion of Angiotensin I to Angiotensin II (a more potent systemic vasoconstrictor).
This inhibits Aldosterone release from the adrenal cortex, depressing renal sodium and fluid retention, thereby decreasing blood volume.
What are the indications of ACE inhibitors?
Hypertension
Heart Failure
Nephropathy
Prevention of Cardiovascular events in high risk patients
Name 3 side effects of ACE Inhibitors
Dry cough (10% of Patients, causing cessation of treatment in 5%) Hypotension Hyperkalaemia Renal Impairment Angioedema
What type of drugs are Isosorbide Mononitrate and Glyceryl Trinitrate (GTN)
Nitrates
What is the mechanism of action of GTN?
- Converted to Nitric Oxide (NO), a potent vasodilator.
- Cardioselective, acting on coronary blood vessels, enhancing flow of blood to ischaemic areas of the myocardium.
- Reduces myocardial oxygen consumption by reducing cardiac preload and afterload.
What are nitrates used for?
- Angina
- Severe hypertension (intravenous GTN is sometimes used in this setting)
What are the side effects of nitrates?
- Headache (incidence varies greatly, between 20-82%, causing cessation of treatment in 10%)
- Postural Hypotension / Dizziness
- Tachycardia
Why is GTN given as a spray/IV and not orally?
GTN is rapidly inactivated by first pass (hepatic) metabolism and therefore cannot be digested – sublingual spray/tablet only.
It can also be given intra-venously.
What types of drugs are Verapamil and Diltiazem
Rate-limiting Calcium Channel blockers
When are calcium channel blockers used?
Supraventricular arrhythmias
Treatment of angina
Hypertension
What are the side effects of verapamil?
Constipation (up to 11.7% of patients)
Flushing / Headache / Dizziness / Hypotension (up to 2.5% of patients)
What are the side effects of Diltiazem?
- GI disturbances (up to 6% of patients)
- Bradycardia (up to 3.6% of patients)
- Peripheral oedema i.e. ankle swelling (up to 15% of patients)
- Dizziness / Headache / Hypotension (up to 4.3% of patients)
What are the important pharmacokinetics/dynamics with Calcium Channel Blockers?
Contra-indicated in heart failure and left ventricular dysfunction due to potent negative inotropy.
Avoid in bradycardia and hypotension.
Do not use with beta-blockers.
Name 3 Non Rate-limiting Calcium Channel Blockers
Amlodipine
Nifedipine
Felodipine
What is the mechanism of action of Amlodipine?
Prevent cellular entry of Ca2+ by blocking L-type calcium channels.
Myocardial and smooth muscle contractility depressed – these drugs mainly affect smooth muscle.
Dilate coronary blood vessels and reduce afterload
What is amlodipine used for?
Hypertension
Treatment of Angina
Give 2 side effects of amlodipine
Ankle oedema (up to 15% of patients)
Abdominal pain / Nausea
Palpitations (up to 4.5% of patients)
Flushing / Headache / Dizziness
Give two examples of statins
Simvastatin
Atorvastatin
Pravastatin
What is the mechanism of action of statins?
- Competitively inhibits HMG CoA Reductase; the rate-determining enzyme in the mevalonate pathway synthesis of cholesterol.
- This causes an increase in LDL-receptor expression, on the surface of hepatocytes.
- Increases hepatic uptake of cholesterol, reducing plasma cholesterol levels.
- Reduces development of athersclerotic plaques.
What are the indications of statins?
Familial hypercholesterolaemia
Prevention of cardiovascular events in high-risk patients.
Give two side effects of statins
Myalgia (5-7% of patients) Myopathy (with creatine kinase elevation) and rhabdomyolysis are rare. GI disturbances (Varied symptoms; up to 6% of patients affected) Liver abnormalities – deranged LFT’s
Which drug is a cardiac glycoside?
digoxin
What is the mechanism of action of digoxin?
- Increases vagal parasympathetic activity and inhibits the Na+/K+ pump, causing a buildup of Na+ intracellularly.
- In an effort to remove Na+, more Ca2+ is brought into the cell by the action of Na+/Ca2+ exchangers.
- The buildup of Ca2+ is responsible for the increased force of contraction and reduced rate of conduction through the AV node.
What are the side effects of digoxin use?
nausea
vomiting
diarrhoea
confusion
What is digoxin used for?
Atrial fibrillation
heart failure
What is important to remember in digoxin use?
Digoxin has a long half-life and maintenance doses may only be required once-daily.
Renal function, age and heart disease are major determinants for safe digoxin dosage.
Which drug is used for Supraventricular / ventricular arrhythmias?
Amiodorone
What is the mechanism of action of amiodorone?
Amidorone blocks cardiac K+ channels, prolonging repolarization of the cardiac action potential.
Restores regular sinus rhythm.
It also slows atrioventricular nodal conduction.
Give two side effects of amiodorone
Photosensitivity skin reactions (up to 75% of patients)
Hypersensitivity reactions
Hyper / Hypothyroidism (linked to high iodine content)
Pulmonary fibrosis
Corneal deposits (69-100% of patients)
Neurological disturbances
GI disturbances / Hepatitis
Which drugs are given in AF
Beta blocker e.g. bisoprolol
Rate limiting calcium channel blocker
Digoxin - second line
DOACs - apixaban, dagigatran
Why can amlodipine not be used in AF?
Causes reflex tachycardia
