Updated: 8/11/2018

Coronary Artery Anatomy

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Snapshot
  • A 70-year-old man presents to the emergency room with chest pain for the past hour. He has a medical history of coronary artery disease, hyperlipidemia, and type 2 diabetes mellitus. He has a 30-pack-year smoking history and drinks alcohol regularly. His electrocardiogram reveals ST-segment elevations in leads V3 and V4. Aspirin is given and he is rushed for an angioplasty. (Myocardial infarction with left main coronary artery involvement)
Anatomy
  • Coronary arteries include
    • right coronary artery (RCA)
      • arises from right aortic sinus
      • supplies right ventricle and His bundle
      • branches
        • sinoatrial nodal artery
          • supplies the sino-atrial (SA) node
        • right marginal artery
          • supplies the right ventricle
    • left main coronary artery (LCA)
      • arises from left aortic sinus
      • branches
        • left circumflex coronary artery (LCX) supplies 
          • lateral and posterior wall of left ventricle
          • anterolateral papillary muscle
          • supplies some blood flow to SA node and AV node
        • left anterior descending artery (LAD) supplies  
          • anterior portion of the interventricular septum
          • anterolateral papillary muscle
          • anterior surface of the left ventricle
          • most common artery to be involved in myocardial infarction
    • posterior descending artery (PDA) supplies 
      • AV node
      • posterior portion of interventricular septum and ventricles
      • posteromedial papillary muscle
  • Coronary arterial system dominance
    • defined by which artery supplies the PDA
    • right dominance
      • 85% of cases
      • RCA gives rise to PDA
    • left dominance
      • 8% of cases
      • LCX gives rise to PDA
    • codominance
      • 7% of cases
      • both LCX and RCA give rise to PDA
  • Coronary sinus
    • the endpoint of coronary flow and is continuous with the right atrium
    • in chronic pulmonary hypertension, coronary sinus becomes dilated
    • blood in the coronary sinus has the lowest oxygen content in the body
      • oxygen saturation levels 30%
  • Left atrium
    • most posterior part of the heart
    • enlargement can compress
      • the esophagus, causing dysphagia
      • the left recurrent laryngeal nerve, causing hoarseness
 
Localization of Myocardial Infarctions (MI)
Leads with ST-Segment Elevation
Location of MI
Vessel(s) Affected
V1-V2
  • Septal
  • LAD
V3-V4
  • Anterior
  • LAD
V5-V6
  • Apical
  • LAD, LCX, or RCA
I and aVL
  • Lateral
  • LCX
V7-V9
  • Posterior
  • RCA and LCX
II, III, and aVF
  • Inferior
  • RCA and LCX
 
Pathology
  • Coronary steal phenomenon
    • myocardial ischemia
      • results from narrowing of coronary arteries after vasodilator use
        • classically, dipyramidole is associated with this
      • dilation of microvessels to non-ischemic tissues can “steal” blood flow away from the heart
 

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Questions (10)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
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(M1.CV.4723) A 55-year-old man with a past medical history of hypertension, hyperlipidemia, and insulin dependent diabetes mellitus presents to the ED with a sudden onset of substernal chest pain and pressure that radiated into his neck and down his left arm. The pain started a few hours ago while he was watching television. It was not relieved by rest. He was given aspirin by EMS en route to the hospital. His current medications are glargine insulin, hydrochlorothiazide, and atorvastatin. He has not had any similar episodes previously. His family history is significant for an uncle who had a heart attack at age 45. He drinks one drink every other day and has a 25-pack-year smoking history. His temperature is 99.0°F (37.2°C), blood pressure is 150/90 mmHg, pulse is 63/minute, respirations are 22/minute, and point-of-care glucose level is 110 mg/dl. Troponin level is elevated. EKG is shown in Figure A. What is the most likely etiology of this patient’s presentation? Review Topic

QID: 108549
FIGURES:
1

Left main coronary artery occlusion

13%

(22/172)

2

Right main coronary artery occlusion

28%

(49/172)

3

Left circumflex artery occlusion

14%

(24/172)

4

Left anterior descending artery occlusion

39%

(67/172)

5

Coronary vasospasm

2%

(3/172)

M1

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(M1.CV.150) A 24-year-old man presents to the emergency room with a stab wound to the left chest at the 4th intercostal space. The patient is hemodynamically unstable, and the trauma attending is concerned that there is penetrating trauma to the heart. Which cardiovascular structure is most likely to be affected by such a wound? Review Topic

QID: 100666
1

Left atrium

33%

(3/9)

2

Left ventricle

0%

(0/9)

3

Right atrium

11%

(1/9)

4

Right ventricle

56%

(5/9)

5

Aorta

0%

(0/9)

M1

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(M1.CV.24) A 49-year-old male presents to the emergency room with dyspnea and pulmonary edema. He reports that he has been smoking 2 packs a day for the past 25 years and has difficulty breathing during any sustained physical activity. His blood pressure is normal, and he reports a history of COPD. An echocardiogram was ordered as part of a cardiac workup. Which of the following would be the most likely finding? Review Topic

QID: 100540
1

Aoritc stenosis

9%

(1/11)

2

Mitral valve insufficiency

18%

(2/11)

3

Left ventricular hypertrophy

45%

(5/11)

4

Coronary sinus dilation

18%

(2/11)

5

Tricuspid valve stenosis

9%

(1/11)

M1

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(M1.CV.48) A healthy 23-year-old male is undergoing an exercise stress test as part of his physiology class. If blood were to be sampled at different locations before and after the stress test, which area of the body would contain the lowest oxygen content at both time points? Review Topic

QID: 100564
1

Superior vena cava

3%

(12/375)

2

Inferior vena cava

11%

(43/375)

3

Coronary sinus

32%

(120/375)

4

Pulmonary artery

45%

(167/375)

5

Pulmonary vein

7%

(27/375)

M1

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(M1.CV.204) In the coronary steal phenomenon, vessel dilation is paradoxically harmful because blood is diverted from ischemic areas of the myocardium. Which of the following is responsible for the coronary steal phenomenon? Review Topic

QID: 100720
1

Venodilation

0%

(0/13)

2

Microvessel dilation

38%

(5/13)

3

Dilation of the large coronary arteries

46%

(6/13)

4

Arterial dilation

15%

(2/13)

5

Volume loss of fluid in the periphery

0%

(0/13)

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(M1.CV.1) A 62-year-old Caucasian male presents to the emergency room with severe substernal chest pain, diaphoresis, and nausea. Imaging reveals transmural myocardial infarction in the posterior 1/3 of the ventricular septum. Which of this patient's coronary arteries is most likely occluded? Review Topic

QID: 100803
1

Left circumflex

33%

(8/24)

2

Left anterior descending

8%

(2/24)

3

Diagonal perforators

4%

(1/24)

4

Septal perforators

4%

(1/24)

5

Right main

50%

(12/24)

M1

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