Coronary Circulation and Conduction System Flashcards

1
Q

What are the 2 main arteries that supply the heart?

A
  • Right Coronary Artery
  • Left Coronary Artery
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2
Q

Where does the endocardium recieve nutrients from?

A

directly from the chambers of the heart

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3
Q

Where do coronary arteries branch from and where do they emerge?

A
  • Ascending Aorta
  • Aortic sinus
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4
Q

When do the coronary arteries fill?

A

During diastole

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5
Q

Where does the RCA arise from?

A

right aortic sinus

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6
Q

Where does the RCA pass between?

A

right auricle and pulmonary trunk

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7
Q

What branch does the RCA give before entering the coronary sulcus?

A

SA nodal branch

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8
Q

What does the SA nodal branch supply?

A

SA node of the conduction system

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9
Q

What branch of the RCA supplies the right atrium?

A

atrial branches

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10
Q

What branch does the RCA give off before turing onto the inferior surface?

A

right (acute) marginal branch

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11
Q

What additional bracnh does the RCA usually give off?

A

Posterior interventricular branch (posterior descending artery)

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12
Q

Where does the RCA anastomose with the LCA

A

In the coronary sulcus and at the apex of the heart

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13
Q

What do the RCA and its branches supply?

A
  • Walls of RA and RV
  • SA and AV nodes
  • Posterior part of IV septum (proximal portion of AV bundle of His)
  • Small areas of the walls of the LA and LV
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14
Q

In what % of people is the RCA dominant?

A

80%

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15
Q

Obstruction of the RCA can lead to ?

A

Inferior infarct

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16
Q

Mild cases of obstruction of the RCA are likely to cause

A

Arrhythmias

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17
Q

Where does the LCA arise from?

A

left aortic sinus between the left auricle and pulmonary trunk

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18
Q

How does the LCA differ from the RCA?

A

Shorts but thicker

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19
Q

What does the LCA divide into when it enters the coronary sulcus?

A
  • Circumflex branch
  • ANterior IV branches
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20
Q

What is the course of the anterior IV branch of the LCA (left anterior descending)?

A

in the anterior IV sulcus

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21
Q

What does the anterior IV branch supply?

A

sternocostal surface

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22
Q

What does the LAD (left anterior descending) anastomose with?

A

Posterior IV branch of RCA at the apex

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23
Q

What coronary artery is most commonly affected by atherosclerosis?

A

Left anterior descending

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24
Q

What branch comes off the circumflex branch of the LCA

A

left marginal branch

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25
Q

Where does the circumflex branch travel?

A

posteriorly along coronal sulcus

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26
Q

What does the circumflex branch anastomose with?

A

Branches of the RCa in the coronary sulcus posteriorly

27
Q

What does the LCA and its branches supply?

A
  • Walls of LA and LV
  • Most of the IV septum inclusing part of the AV bundle
28
Q

Obstruction of the left anterior descending artery causes?

A

Anterior infarct

29
Q

Obstruction of the circumflex artery causes?

A

Lateral infarct

30
Q

Anterior infarct causes

A

Loss of LV function and Ventricular fibrillation

31
Q

What is the left ventricle and septum mostly supplied by?

A

left coronary artery

32
Q

What is the right ventricle and the part of the septum containing the bundle of HIs mistly supplied by?

A

Right coronary artery

33
Q

What is coronary dominance determined by?

A

The artery that gives off the posterior IV/ posterior descending artery

34
Q

What is atheroslcerosis?

A

Condition in which arteries become clogged with fatty substances called plaques and atheroma

35
Q

Sites of coronary artery occlusion due to atherosclerosis in order of frequency

A
  1. LAD of LCA
  2. RCA
  3. Circumflex of LCA
36
Q

Occlusion of coronary arteries may…

A

damage the conducting system

37
Q

How does occlusion of coronary arteries damage the conducting system?

A
  • LAD to septal branches supplying AV bundles
  • RCA supplies both SA and AV nodes
  • Heart block

Symptom = bradycardia

38
Q

What is bundle branch block?

A
  • Ischaemic bundle branch ceases to conduct impulses appropriately
  • USes altered pathways for depolarisation
  • Impulse travels through myocytes (slower speed) = producing a prolonged QRS complex
  • Loss of ventricular function
39
Q

What ECG leads correspond to the lateral portion of the heart?

A
  • I
  • aVL
  • V5
  • V6
40
Q

What ECG leads correspond to the inferior portion of the heart?

A
  • II
  • III
  • aVL
41
Q

What ECG leads correspond to the septal portion of the heart?

A
  • V1
  • V2
42
Q

What ECG leads correspond to the anterior portion of the heart?

A
  • V3
  • V4
43
Q

What is coronary artery bypass grafting?

A

bypass of the occluded portion of the vessel?

44
Q

Describe the path of cardiac veins

A

accompany coronary arteries and their branches

45
Q

Great cardiac vein

A

(anterior IV vein)

  • accompanies LAD
  • Joins coronary sinus
46
Q

What artery does the small cardiac vein accompany?

A

right marginal branch

47
Q

Where do anterior cardiac veins drain into?

A

Independently into the RA

48
Q

Where does the middle cardiac vein run?

A

with posterior interventricular artery and drains into the coronary sinus

49
Q

Where do the majority of cardiac veins drain?

A

coronary sinus

50
Q

Where is the coronary sinus?

A

Lies between LA and LV

51
Q

What is the coronary sinus surrounded by?

A

muscle fibres from the LA

52
Q

What is the function of the coronary sinus?

A

Drain approx 60% of the venous blood of the heart into the RA

53
Q

Within the cardiac condution system there is a specialised group of modified muscle cells that can:

A
  • generate electrical impulses without external stimuli
  • lie immediately beneath the endocardium
  • distribute electrical impulses through the myocardium
  • cause the heart to contract in a proper sequence
54
Q

What are the components of the conduction system?

A

o Sino-atrial node (SAN)

o Atrioventricular node (AVM)

o Atrioventricular bundle (Bundle of His)

§ Left bundle branch

§ Right bundle branch

o Purkinje fibres

**None of them are macroscopic

55
Q

How does the autonomic nervous system affect the cardiac cycle?

A

shortens or prolongs the duration of the cycle

56
Q

Sino-Atrial Node

A
  • Pacemaker
  • The basic depolarisation rate of the SA node is 70 to 80 beats per minute
  • Located anterior to the opening of the SVC, upper end of crista terminalis
  • Usually supplied by branches of the RCA
57
Q

AV Node

A
  • Located at the poster-inferior part of IA septum, close to the opening of the coronary sinus
  • Usually supplied by AV nodal branch of the right coronary artery
58
Q

Atrioventricular Bundle

A

Bundle of His

o Continuation of AV node

o Runs along the membranous part of the IV septum

o Splits into right and left bundle branches

o Both right and left split into Purkinje fibres

  • The AV bundle of His should be the only conductive route through the fibrous skeleton
  • This system ensures synchronous contraction, in the correct sequence, toward the outflow of each chamber
59
Q

Right Bundle Branch

A
  • Descends on the right side of the membranous part of the IV septum
  • Enters the septomarginal trabecula to reach the base of the anterior papillary muscles
  • Splits into Purkinje fibres which spread out into the ventricular walls
60
Q

Left Bundle Branch

A
  • Descends on the left side of the membranous part of the IV septum
  • Splits into Purkinje Fibres
61
Q

Superifical and deep cardiac plexus

A
  • Lies inferior to the aortic arch, adjacent to the bifurcation of both the pulmonary trunk and the trachea
  • Supply conduction system, coronary blood vessels, and myocardium
62
Q

Presynpatic sympathetic fibres travel in T1-5(6) spinal nerves

A
  • Increase the heartbeat and force of contraction
  • Dilate coronary arteries
63
Q

Parasympathetic fibres reach in vagus

A
  • Decrease the heart beat and force of contraction
  • Constrict coronary arteries
64
Q

Nerve supply of the heart

A