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III.K

Coronary Arteries

5 cards

Notes

Anatomy on echo

  • Left main coronary artery (LMCA) - arises from the left sinus of Valsalva at ~2 o'clock (PSAX at AV level).
  • Right coronary artery (RCA) - arises from the right sinus at ~11 o'clock.
  • LMCA bifurcation - into LAD (anterior) and LCx (posterior).
  • LMCA distance from ostium to bifurcation: 6–10 mm typically.
  • Non-coronary cusp (NCC) is posterior; no coronary artery arises from it.

Coronary dominance

  • Right-dominant (~80–85 %): PDA arises from RCA → supplies inferior wall, posterior 1/3 of septum, posterior papillary muscle.
  • Left-dominant (~10 %): PDA arises from LCx.
  • Co-dominant (~5 %): PDA supplied by both.

Coronary anomalies

  • ALCAPA (anomalous LCA from PA) - infantile presentation with heart failure. In adult: MR from ischemic papillary dysfunction. LCA absent from left sinus; retrograde flow visible in dilated coronary arteries.
  • Anomalous LCA from RCA (or right sinus) - can course between aorta and PA → high SCD risk in young athletes.
  • Anomalous RCA from LCA (or left sinus) - similar interarterial course risk.
  • Coronary AV fistula - communication with cardiac chamber or PA; usually asymptomatic but can cause steal or high-output failure.

Coronary flow reserve (CFR)

  • Ratio of peak-hyperemic to baseline flow velocity in a coronary artery.
  • Normal CFR > 2.5–3.0.
  • Reduced CFR indicates functionally significant epicardial stenosis or microvascular dysfunction.
  • Best assessed in the LAD by transthoracic Doppler in the distal LAD (modified apical view) at rest and during pharmacologic hyperemia (adenosine, dipyridamole).

Coronary sinus vs coronary artery

  • CS lies in the posterior AV groove and empties into the RA.
  • Do not confuse a dilated coronary sinus with a coronary artery on TEE - CS is thin-walled, low-flow, drains into RA; artery is thicker-walled with pulsatile arterial flow.

Cards

  • basicIII.K-001
    From which aortic cusps do the LMCA and RCA arise?
    → LMCA arises from the LEFT coronary sinus. RCA arises from the RIGHT coronary sinus. No coronary artery arises from the NON-coronary (posterior) sinus.
  • basicIII.K-002
    Define coronary dominance and state approximate frequencies.
    → Right-dominant (~80–85%): PDA arises from RCA — supplies inferior wall, posterior 1/3 septum, posterior papillary muscle. Left-dominant (~10%): PDA from LCx. Co-dominant (~5%).
  • basicIII.K-003
    Which anomalous coronary course carries the highest SCD risk in young athletes?
    → Interarterial course of an anomalous coronary between the aorta and pulmonary artery (e.g., anomalous LCA from the right sinus, or RCA from the left sinus).
  • basicIII.K-004
    Describe ALCAPA and its typical adult presentation.
    → Anomalous origin of the LEFT coronary artery from the PULMONARY ARTERY. In infants: severe HF with ischemia. Untreated adult survivors present with ischemic mitral regurgitation and retrograde flow in dilated coronary collaterals.
  • basicIII.K-005
    Define coronary flow reserve (CFR) and its normal value.
    → CFR = peak hyperemic coronary flow velocity / baseline flow velocity (measured by transthoracic Doppler, usually in the distal LAD). Normal > 2.5–3.0. Reduced CFR indicates significant epicardial stenosis or microvascular disease.