Cardiovascular Pharamacology Flashcards
What are the four heart valves?
Tricuspid
Pulmonary
Aortic (bicuspid)
Mitral
What does semi-lunar valves do?
prevent backflow of blood from pulmonary trunk & aorta into ventricles.
What does atrioventricluar valves do?
Prevent backflow of blood from ventricles to atria when ventricles contract
What are myocardial cells or mycocytes?
Contractile cells
What does the pulmonary circuit do?
Transports deoxygenate blood from the right side of the heart to the lungs and returns oxygenated blood to the left side of the heart
What does the systemic circuit do?
Transports oxygenated blood away from the heart to the body and returns deoxygenated blood back to the heart
What type of cells can a cardiac muscle be?
Contractile or autorhythmic
What is the intrinsic conduction system?
Internal regulating system responsible for rhythmic contraction of the heart
Where are autorhythmic cells found?
Sinoatrial (SA) node Atrioventricular (AV) node AV (bundle of His) Left and right bundle branches Purkinjie fibres
What is depolarisation current carried out by?
Slow Ca2+ currents- slower action potential
Why does slow depolarisation occur?
Due to opening of Na+ and closing of K+channels
What occurs in the repolarisation phase?
Rapid influx of K+ due to activation of K+ channels
What occurs in the depolarisation phase?
Once pacemaker potential reaches threshold Ca2+ channels open and a rapid influx of Ca2+ occurs leading to a self-induced action potential
What are both conduction and contraction dependent on?
Ion channels
What is the % contractile vs autorhythmic cells?
99% contractile myocytes
1% autorhythmic cells
How many phases is the action potential in typical cardiomyocytes composed of?
5 phases (0-4)
What are three features of cardiac pacemaker cells that makes their action potentials different?
Automaticity
Unstable membrane potential
No rapid depolarisation phase
Why is the refractory period important?
At very high heart rates, the heart would be unstable to adequately fill with blood and therefore ventricular ejection would be reduced
What is the absolute refractory period (ARP)?
When the cell is completely unexcitable to a new stimulus
What is the effective refractory period?
When the ARP and short segment of phase 3 during which a stimulus may cause the cell to depolarise minimally but will not result in a propagated action potential (i.e. neighbouring cells will not depolarise)
What is the relative refractory period (RRP)?
A greater than normal stimulus will depolarise the cell and cause an action potential
What is the supranormal period?
A hyperexcitable period during which a weaker than normal stimulus will depolarise the cells and cause an action potential. Cells in this phase particularly susceptible to arrhythmias when exposed to an inappropriately timed stimulus, which is why one must synchronize the electrical stimulus during cardioversion to prevent inducing ventricular fibrillation
What receptors does calcium activate?
ryanodine receptors on the sarcoplasmic reticulum
What does calcium enter the cardiomyoctye via?
L-type calcium channels
What does calcium return to the SR via?
The SERCA calcium channel
What is ischemic heart disease?
Lack of oxygen to the heart
What is ischemic heart disease also know as?
Coronary heart disease
What do the coronary arteries do?
Supply the heart with blood and oxygen
What do cardiac veins do?
Remove carbon dioxide and waste products from the heart tissue
What does the left coronary artery divide into?
Circumflex artery and the left anterior descending artery
Is the right coronary artery split into divisions?
No
What are the main symptoms of CHD?
Chest pain (angina) and a heart attack
What are the group of condones for CHD?
- Stable angina
- Unstable angina
- Myocardial infarction
- Sudden cardiac death
What is stable angina?
Related to myocardial ischemia (effort angina). Chest discomfort occurs when some activity (e.g. walking or running) has taken place
What is treatments for stable angina?
Sublingual nitroglycerin
What can also contribute to the occurrence of stable angina?
Emotional stress, heavy meals and cold weather
How long do the symptoms last for stable angina?
Several minutes after activity
What is unstable angina?
Angina pectoris that changes or worsens
What are the three features of unstable angina?(only need one of the three feature for unstable angina)
- Occurs at rest
- It is servers and of new occurrence
- Occurs with a pattern
When does a myocardial infarction occur?
When blood flow stops to a part of the heart causing damage to the heart muscle
What is the main symptom of a myocardial infarction?
Chest pain
What is a myocardial infarction mainly due to?
CHD
What are some risk factors of a myocardial infarction?
Increased blood pressure, smoking, diabetes, lack of exercise, obesity, poor diet, increased cholesterol, genetics
What is sudden cardiac death?
Abrupt loss of consciousness within one hour of onset of acute symptoms.
What is the main cause of sudden cardiac death?
Ventricular fibrillation- heart activity becomes disordered
What do post mortems show of people who have died of sudden cardiac death?
Chronic high-grades stenosis of at least one segment of a major coronary artery.
What is left ventricular hypertrophy?
Increased muscle mass which decreed volume of blood through the heart. A cause of sudden cardiac death
What are the symptoms of angina?
Centre chest pains that may spread to arm, neck, jaw, back or stomach and burning sensations ect. Similar to symptoms of indigestion
What is a heart attack?
Permanently damage heart muscle
What are the symptoms of a heart attack?
Pain in the chest, dizziness, breathlessness, nausea.
How long does a heart pain have to be in order to be classed as a heart attack?
Longer than 15 minutes
What can not treat a heart attack and why not?
Symptoms not relieved by using nitrate tablet or spray due to heart blockage
What does nitrate tablet or spray do?
Dilates blood vessels
What is heart failure?
Heart to weak to pump blood around the body. can be a fluid up of build.
What substance can cause the arteries to become rigid and what is the condition called?
Waxy plaque build up.
Atherosclerosis
What is hypoxia?
Decrease in oxygen supply despite adequate perfusion
What is anoxia?
Absence of oxygen despite adequate perfusion
What does the a atheromatous plaque cause?
Inflames blood vessel walls. Increases risk of blood clot and a heart attack.
Give a example of a few things a atheromatous plaque contains?
Inflammatory cells and leukocytes such as macrophages also lipoproteins, debris ect. And they stick to plaque once its ruptured
What develops when a atheromatous plaque ruptures and blocks a blood vessel and why is still not very useful?
New blood vessels develop that go around the blockage however the diameter is much smaller so during increased exertion or stress new vessels are not adequate
What is a ischemic stroke?
Blood vessel to the brain is blocked
What is a haemorrhagic stroke?
Blood vessel in the brain bursts
What do pharmacology treatments do?
They treat the symptoms and get rid of the clot. Some slow the heart down to decrease demand or they increase oxygen supply.
What treatments don’t decrease demand on the heart?
Percutaneous transluminal coronary angioplasty (opens up blocked coronary arteries)
What do nitrates do?
Alter both myocardial oxygen supply and demand
What do beta blockers do?
Decrease demand of the heart
What do calcium channel blockers do?
Decrease oxygen demand
What are the eight different pharmacological agents used in heart treatment?
- Anti platelets - decrease clot
- Stations- reduce cholesterol
- Beta blockers
- Nitrates
- ACE inhibitors
- Angiotensin 2 receptor antagonist
- Calcium channel blockers
- Diuretics
What agents decrease myocardial oxygen demand and effect heart rate and contractility?
Beta blockers
Calcium channel blockers
What agents decrease myocardial oxygen demand and effect preload and afterload?
Organic nitrates
Calcium channel blockers
What agents increase myocardial blood blow and effect coronary blood flow and/or regional myocardial blood flow?
Vasodilator Statins Anti-thrombotics Stents Angioplasty CABG surgery
What do antiplatelet do?
Decrease platelet aggregationand inhibit thrombusformation
What is activated platelet aggregating a process regulated in part by?
prostaglandins
Give a example of a ADP-receptor blockers
Ticlopidine
Clopidogrel
Prasugrel
What does Ticlopidine require for activation?
Oxidation by enzyme CYP2C19
Why does Clopidogrel not require activation by CYP219?
The relevant oxygen at the thiophene ring is already present in the prodrug
What is the mechanism of action of ADP-receptor blockers?
Act by inhibiting the ADP-dependent pathway off platelet activation