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Cardiac surface anatomy

Auscultatory Zones

Aortic: RUSB (right upper sternal border)

Pulmonic: LUSB (left upper sternal border)

Tricuspid: 4LICS (4th left intercostal space), on the sternal border

Mitral: 5 LICS (5th left intercostal space), several cm lateral to the 4LICS

Apex Beat

Located anywhere from the 4th to 5th intercostal space, 6-10 cm lateral to midline

Borders of the Heart

Superior: line connecting inferior 2nd L costal cartilage to the superior 3rd R costal cartilage

Inferior: line from the inferior R border of the sternum to the intersection of the 5th intercostal space and the midclavicular line

Right: line drawn from 3rd R costal cartilage to 6th R costal cartilage

Left: line from the L ends of the superior and inferior lines

ECG Lead Placement

Note that not all ECG leads have identical sensitivity for ischemia detection. Because not all leads are monitored intraoperatively, judicious selection becomes important

Individual Lead Sensitivity for Detecting Ischemia – V5: 75% – V4: 61%

V4 and V5 sensitivity is 90%, which is better than the usual lead II/V5 combination (sensitivity 80%). The best combination is leads II, V4, and V5, which has a sensitivity of 98%.

Other References

  1. Keys to the Cart: May 21, 2018; A 5-minute video review of ABA Keywords Link