Coronary circulation Flashcards
What do coronary arteries do?
Supply myocardium with oxygen
What do cardiac veins do?
Drain away deoxygenated blood
Where does circumflex artery come from?
Left artery
Where does posterior descending artery come from?
Right coronary artery
What is regurgitation?
Valve is incompetent - opens in abnormal way
Where does left coronary artery come from?
Aorta - left cusp of aortic valve
Where does right coronary artery come from?
Right cusp of aortic valve
Coronary arteries
- Right coronary artery (RCA)
- RCA ostium - 3.2mm
- Left coronary artery (LCA)
- LCA ostium - 4mm
- Anterior interventricular artery (LAD)
- Circumflex artery
- Posterior interventricular artery (posterior descending)
- Right marginal artery
- Left marginal artery
Left coronary artery
- Usually larger
- Branches into LAD (comes off very quickly 2cm) (anterior interventricular artery)
- Left circumflex - left marginal artery is a branch of this
Right coronary artery
- In -85% of people, RCA gives off posterior descending artery, right dominant
- Right marginal artery
- Supplies SA nodal artery in 60% of people
- Supplies atrioventricular nodal branch in 80-90% of people
- (otherwise may be supplied by left circumflex, left dominant)
Venous drainage of heart
Small, middle and great cardiac veins and coronary sinus
What is coronary sinus?
Collection of veins draining together, drains blood from myocardium
Conduction in heart
- SAN - heart’s internal pacemaker RA wall initiates cardiac cycle setting rhythm. Electrical impulse spreads to:
- Atrioventricular node: connected top bundle of His
- Electrical signals arise in SAN in RA, which stimulates the atria to contract. The signals travel to the AVN (interatrial septum). After a delay, signal diverges and is conducted through L and R bundle of His to respective Purkinje fibres
What does accelerator nerve do in heart?
Releases neurotransmitter at SAN to increase HR
What does vagus nerve do in heart?
Releases neurotransmitter at SAN to decrease HR
What do carotid bodies do?
Chemoreceptors near bifurcation of carotid artery. Detect changes in ppO2 and ppCO2. Send feedback via branches of glossopharyngeal nerve
What do aortic bodies do?
Chemoreceptors in aortic arch send feedback via afferent branches of vagus nerve
What does carotid sinus do?
Baroreceptors at base of internal carotid artery, innervated by branch of glossopharygneal
What is P?
Atrial depolarisation
What is QRS?
Ventricular depolarisation
What is T?
Ventricular depolarisation
What is the widow maker?
Blockage of left main coronary artery
What is percutaneous coronary angioplasty?
- Through skin and arteries, find a point that artery is blocked, pass wire across blockage
- Inflate tube to push plaque against wall
- Stent holds plaque away
- Used to open blocked coronary artery, treat stenosis, restore arterial blood flow
- Coronary catheterisation (visualise vessels on x-ray)
- Coronary angioplasty
What is CABG?
- Take sliver of vein and bypass blockage
- Can use left internal mammary artery which is diverted to LAD (pedicle)
- Long saphenous vein is removed from a leg, one end is attached to aorta and the other to the obstructed artery immediately after obstruction
Characteristics of cardiac pain
- Shoulder and left arm because sympathetic afferent fibres travel along here to T1-4 of spinal cord
- Jaw and neck pain too
- Afferents from vagus (wandering) nerve also carry sensory fibres from heart
- Vagus nerve synapse in medulla (nucleus tractus solitarius) then descend to excite upper cervical nerve cells (spinothalamic tract) which is felt as neck and jaw pain
- Neural network between brain, emotion, memory centres and broken heart
