The Coronary Circulation

7/29/2019 The Coronary Circulation

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Lecture 3- The Coronary Circulation

1. Exit valves from ventricles- Pulmonary and aortic valve- Comprised of three semilunar cusps

-

- Aortic sinus : a dilatation [orifice being dilated] between the aortic wall and each of thesemilunar cusps of the aortic valve; from two of these sinuses the coronary arteries take

origin.


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Aortic valve Superior to each valve is the aortic sinus There are generally three aortic sinuses : the left posterior ( which gives

rise to left coronary artery), the anterior( give rise to right coronary

artery), and the right posterior ( no vessels arise from the right posterior

aortic sinus- also known as non-coronary sinus)


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Right coronary artery From the right aortic sinus Sinuatrial node branch

Site of the fastest depolarisation All hearts cells have the ability to generate the electrical

impulses that trigger cardiac contraction, the SAN normally

initiates it simply because it generates impulses slightly faster

than other areas with pacemaker potential.

Depolarisation becomes slower when it reaches AV andventricle

Right auricle and infundibulum Infundibulum- the conus arteriosus[ conical pouch formed from

the upper and left angle of right ventricle in the chordate heart,

from which the pulmonary trunk arises] is the outflow portion of

the right ventricle, known as infundibulum of the heart[ is a

funnel-shaped cavity or organ]


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A-V groove Right coronary artery travel between right atrium and right

ventricle

Right marginal branch Right marginal branch of right coronary artery ( or also known as

right marginal artery)is a large marginal branch which follows

the acute margin of the heart and supplies branches to both

surfaces of the right ventricle

AV nodal branch It electrically connects atrial and ventricular chambers Is an area of specialised tissue between the atria and the

ventricles of the heart, in the posteroinferior region of

interatrial septum near the opening of coronary sinus


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## coronary sinus- opens into the right atrium between the inferior vena

cava and the atrio-ventricular orifice

Posterior interventricular artery (PIVA) Is an artery running in the posterior interventricular

sulcus[groove that separate ventricles of the heart] to the apex

of the heart where it meets with the anterior interventricular

artery (AIVA)

Septal branch Supply blood to posterior atrioventricular septum,

Arteriolar anastomoses [ alternate pathways for blood]

Refers to connection between blood vessels or between othertubular structures such as loops of intestine.

SUMMARY Right coronary artery supplies

RA and most RV Diaphragmatic surface of LV Posterior 1/3 septum SAN[60%] ; AVN[80%]

Left coronary artery Is an artery that arise from the aorta above the left cusp of the aortic

valve and feeds blood to the left side of the heart.

Left auricle and infundibulum It typically runs for 1 to 25 mm and then bifurcates into the anterior

interventricular artery (AIVA) also called left anterior descending(LAD)

artery and left circumflex artery(LCX)

Left marginal artery is a branch of the circumflex artery Summary

Left coronary artery supplies to :

LA, most LV


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Anterior surface of RV Anterior 2/3 of IV septum SAN [40%]; AVN[20%]

2. Anastomoses- Anteriolar anastomoses

In septum In posterior wall of LV Occlusion [blockage]: Angina, AMI[Myocardial Infarction] Gives time for healthy arterioles to open

- Surface ( Capillary) Anastomoses Apex AV groove With pericardial arteries


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3. DOMINANCE: Depends on PIVA- 60%+ of patients the right coronary artery(RCA) is said to be dominant because it

supplies circulation to the inferior portion of interventricular septum via the right

posterior descending coronary artery

- 15% of patients the RCA is said to be non-codominat because it does not supplycirculation to the inferior portion of interventricular septum via the right posterior

descending coronary artery

- In 8% of patients- the left coronary artery(LCA) is dominant because it travels to thecross section of AV groove and the posterior interventricular

http://www.youtube.com/watch?feature=endscreen&NR=1&v=eefHDKGWSR4

4. Myocardial Infarction: Complications- Possible within 20 minutes onset- Arrhythmias [disturbance or loss of regular rhythm]/ heart block- Cardiogenic shock/ CCF- Valve problems : acute mitral regurgitation[ a disorder of the heart in which the mitral

valve does not close properly when the heart pumps out blood- abnormal leaking of

blood from the left ventricle, through mitral valve, and the into left atrium, when left

ventricle contracts- ie regurgitation of blood back into the left atrium]

Papillary muscles may die off due to blockage in coronary artery
http://www.youtube.com/watch?feature=endscreen&NR=1&v=eefHDKGWSR4http://www.youtube.com/watch?feature=endscreen&NR=1&v=eefHDKGWSR4http://www.youtube.com/watch?feature=endscreen&NR=1&v=eefHDKGWSR4


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Can predict which coronary artery is blocked by injury pattern on the ECG

5. Veins of the Heart- The coronary sinus

o Receives 60% venous blood opens at the lower end of the AV groove into theposterior wall of the right atrium


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oo Receives :

Great cardiac vein(LAD/LCx) Middle cardiac vein(PIVA) Posterior vein of the LV Small cardiac vein(MA)

o Anterior cardiac veins Comprise three or four small vessels which collect blood from the front of

the right ventricle and open into the right atrium

Right marginal vein frequently opens into the right atrium and is thereforesometimes regarded as belonging to this group

Cross anterior Surface RV Drain directly into RA ( unlike most cardiac veins which usually end in the

coronary sinus

Drain remaining 40%o Venae cordis minimae

Smallest cardiac vein: numerous small veins arising in the muscular wallsand draining independently into the cavities of the heart, particularly the

right atrium and ventricle

Drains directly into all 4 chambers Valveless- forms AV shunts/ Collateral[ secondary or accessory] Circulation for parts of myocardium


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6. Blood supply: Pericardiumo Pericardiacophrenic arteries(internal thoracic)is a long slender branch of the

internal thoracic artery. It accompanies the phrenic nerve, between pleura and

pericardium, to the diaphragm, to which it is distributed.

oo Coronary arterieso Supply from nearby structures/ extra-cardiac anastomosis [ it anastomoses with

musculophrenic and inferior phrenic arteries]


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The Coronary Circulation

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