Human Anatomy Vol 1

PERICABDIUM AND HEART

These anastomoses are of little ptactical value. They

are not able to provide an alternative source of blood

in case of blockage of a branch of a coronary. Blockage

of arteries or coronary thrombosis usually leads to

death of myocardium. The condition is called myo-

cardial infarction.

Left ventricle

Right

Right ventricle

Anterior Area by the suppliedleft

intenventricular oroove Anterior coronary artery

Fig. 18.24: Transverse section through the ventricles showing

the areas supplied by the two coronary arteries

3 Anterior part of the interventricular septum

(Fis. 18.24).

4 A part of the left branch of the AV bundle.

Cordioc Dominonce

In about 10% of hearts, the right coronary is rather small

and is not able to give the posterior interventricular

branch. In these cases the circumflex artery, the

continuation of left coronary provides the posterior

interventricular branch as well as to the AV node. Such

cases are called left dominant.

Mostly the right coronary giv inter-

ventricular artery. Such hearts are ri t. Thus

the artery giving the posterior interventricular branch

is the dominant artery.

Collolerol Circulolion

The two coronary arteries anastomose with each other

in myocardium.

The coronary arteries anastomose with the following:

1 Vasa vasorum of the aorta.

2 Vasa vasorum of the pulmonary arteries.

3 The internal thoracic arteries.

4 The bronchial arteries.

5 The phrenic arteries. The last three anastomose
through the pericardium. These channels may open
up in emergencies when both coronary arteries are
obstructed.
Retrograde flow of blood in the oeins may irrigate the
myocardium.

Area supplied by the

right coronary artery

Posterior Posterior

interventricular

groove

Thrombosis of coronary artery is a common cause

of sudden death in persons past middle age. This

is due to myocardial infarction and ventricular

fibrillation (Fig. 18.25).

Incomplete obstruction, usually due to spasm of

the coronary artery causes angina pectoris, which

is associated with agonising pain in the precordial

region and down the medial side of the left arm

and forearm (Fig. 78.26). Pain gets relieved by

putting appropriate tablets below the tongue.

Coronary angiography determines the site(s) of

narrowing or occlusion of the coronary arteries

or their branches.

Angioplasty helps in removal of small blockage.

It is done using small stent or small inflated

balloon (Fig. 18.27) through a catheter passed

upwards through femoral artery, aorta, into the

coronary artery.

If there are large segments or multiple sites of

blockage, coronary bypass is done using either

great saphenous vein or internal thoracic artery

as graft(s) (Fig. 18.28).

Fig. 18.25: Myocardial infarction due to blockage of anterior

interventricular branch of left coronary artery