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Cardiovascular

Heart Anatomy

The heart is a four-chambered pump with paired atrioventricular and semilunar valves, coronary arterial supply, and a specialized conduction system enclosed by the pericardium. ECG-gated CT and cardiac MRI now provide detailed morphologic, functional, and tissue characterization, complementing echocardiography. Understanding chamber morphology, coronary distribution, and valve planes is essential for ischemic, valvular, and structural assessment.

Key Structures

  • Chambers: right atrium (receiving SVC/IVC/coronary sinus), right ventricle (trabeculated with the moderator band), left atrium (four pulmonary veins), left ventricle (thick-walled systemic pump)
  • Valves: tricuspid and mitral (atrioventricular) and pulmonary and aortic (semilunar); the aortic-mitral fibrous continuity anchors the fibrous skeleton
  • Coronary arteries: RCA (right AV groove, gives PDA in right dominance), left main dividing into LAD (anterior interventricular groove) and LCx (left AV groove)
  • Interventricular and interatrial septa; membranous and muscular portions of the ventricular septum
  • Myocardium: layered muscle assessed by 17-segment model mapped to coronary territories
  • Pericardium: fibrous and serous layers with a normal small physiologic fluid volume; pericardial recesses around the great vessels
  • Conduction system: SA node (high RA), AV node, His bundle, and bundle branches (inferred, not directly imaged)

Imaging Planes & Modalities

  • Cardiac MRI cine SSFP in standard planes (2-, 3-, 4-chamber and short axis) for function, volumes, and wall motion
  • Late gadolinium enhancement and T1/T2 mapping/ECV for infarct, fibrosis, edema, and infiltration
  • Coronary CT angiography (ECG-gated) for coronary stenosis, anomalies, and plaque; calcium scoring for risk
  • Echocardiography as first-line for valves, function, and pericardium; Doppler quantifies gradients and regurgitation
  • Short-axis stack for the 17-segment model; valve-plane and inflow/outflow views for valvular assessment
  • Perfusion imaging (stress MRI/CT/nuclear) links territory to inducible ischemia

Landmarks & Normal Values

  • Normal LV wall thickness ~6-10 mm; LV ejection fraction normally ~55-70%
  • Coronary dominance defined by the vessel supplying the PDA (right-dominant in ~85%)
  • Aortic root and annulus dimensions guide valve sizing (e.g., TAVR planning)
  • 17-segment model links apical/mid/basal walls to LAD, LCx, and RCA territories
  • Pericardial thickness normally ≤2-4 mm; thickening suggests constrictive physiology
  • Coronary sinus drains into the right atrium and marks the posterior AV groove

Anatomical Variants

  • Coronary anomalies: anomalous origin (interarterial course is high-risk), separate LAD/LCx ostia, myocardial bridging
  • Left dominant or codominant coronary circulation
  • Persistent left SVC draining to a dilated coronary sinus
  • Patent foramen ovale and atrial septal aneurysm
  • Prominent Chiari network, crista terminalis, and Eustachian valve mimicking RA masses
  • Pericardial recesses (especially the superior aortic recess) mimicking adenopathy or dissection

Pathology Correlation

  • Coronary territory mapping localizes infarcts; subendocardial versus transmural LGE indicates viability
  • Non-ischemic LGE patterns (mid-wall, epicardial) suggest myocarditis, sarcoid, or cardiomyopathy
  • Valve morphology (e.g., bicuspid aortic valve) predisposes to stenosis and aortopathy
  • RV morphology and moderator band anatomy aid in arrhythmogenic cardiomyopathy and congenital assessment
  • Pericardial anatomy underlies effusion, tamponade physiology, and constriction
  • Septal anatomy relates to VSDs, hypertrophic cardiomyopathy, and shunt evaluation

Pitfalls & Mimics

  • Normal RA structures (Chiari network, crista terminalis) mimicking thrombus or mass
  • Pericardial recess fluid mistaken for lymphadenopathy or aortic dissection
  • Motion/misregistration and stair-step artifact on CTA simulating stenosis or dissection
  • Chemical-shift and blooming from calcium/stents overestimating coronary stenosis
  • Physiologic apical thinning misread as infarct on CT/MRI
  • Inadequate gating causing blurred valves and pseudo wall-motion abnormalities

References

  • Miller, Reddy. Cardiac Imaging: The Requisites
  • Kramer et al. SCMR Standardized Cardiovascular MR Protocols
  • Cerqueira et al. AHA 17-Segment Myocardial Model
  • Netter. Atlas of Human Anatomy

⚕️ Educational reference — correlate with clinical context and confirm with a qualified radiologist.