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Posterior STEMI Infarction

Posterior STEMI infarction

Posterior Wall Infarction

• Right dominant coronary artery supplies:
• The right ventricle
• The right part of the posterior wall
• The medial part of the inferior wall
• The lower part of the septum
• Depending on the location of occlusion, an infarction may occur in:
• The right ventricle
• The posterior wall
• The inferior wall
• Left dominant coronary artery supplies (via LCx):
• The lateral part of the inferior wall
• The posterior wall
• The basal part of the left ventricle
• Depending on the location of occlusion, an infarction may occur in:
• The lateral wall
• The posterior wall
• The inferior wall

Posterior Wall and Standard 12-Lead ECG

• The standard 12-lead ECG includes:
• Chest leads (V1-V6)
• Limb leads (I, II, III, aVF, aVL, aVR)
• The standard ECG does not
• "look at" the posterior wall
  
  
• Posterior STEMI shows:
• ST depressions (V1-V4)
• These are reciprocal ST depressions
• ST elevations (V7-V9)
• V7-V9 leads are standardly used
  
  
• Isolated posterior STEMI
• Is often mistakenly interpreted as ischemia
• due to ST depressions in V1-V4
• Leads V7-V9 are often overlooked

Posterior Leads (V7-V9)

• Leads V4-V6 are disconnected and placed on the left side of the back
• On the ECG record, they are then marked as (V7-V9)
• Posterior leads (V7-V9) are placed
• at the level of lead V6 (5th intercostal space)
• V7 (Left axillary line)
• V8 (Left scapular line - tip of the scapula)
• V9 (Left paravertebral line)
  
  
• Posterior STEMI shows ST elevation in at least 1 lead (V7-V9)
• ST elevations do not need to be in 2 adjacent leads

Acute Inferior, Posterior, and Lateral STEMI

• Sinus Rhythm
• Inferior STEMI
• ST Elevations (II, III, aVF) (V5-V6)
• ST elevation III > II (indicative of right coronary artery occlusion)
• Lateral STEMI
• The right coronary artery often supplies the posterior wall and apex of the left ventricle
• Hence, ST elevations (V5-V6) may occur
• Posterior STEMI
• ST depressions in V1-V3
• We should place posterior leads V7-V9 on the patient
• This is a proximal occlusion of the dominant right coronary artery

Acute Postero-Lateral STEMI

• Sinus Rhythm
• Atrial Extrasystole
• Lateral STEMI
• ST Elevations (V5-V6)
• Posterior STEMI
• ST Depressions (V1-V3)
• We should place posterior leads V7-V9 on the patient
• On coronary angiography:
• A: Proximal occlusion of the left circumflex artery (LCx)
• B: LCx after PCI and stent placement

Acute Inferior and Posterior STEMI

• Sinus Rhythm
• AV Block II Degree with 2:1 Conduction to the Ventricles
• Often occurs with inferior wall infarction
• Every 2nd P wave is blocked
• Frequency of P waves: 96/min.
• Frequency of QRS: 48/min.
• ST elevations have the shape of Padree's wave
• Inferior STEMI
• ST elevations in inferior leads (II, III, aVF)
• ST elevation III > II
• Reciprocal ST depressions (I, aVL)
• Indicates occlusion of the dominant right coronary artery
• Posterior STEMI
• Reciprocal ST depressions in V1-V3
• The patient should be placed with posterior leads V7-V9
• There is a high probability of also having right ventricular STEMI
• Leads V1 and V2 are reciprocally altered due to posterior STEMI
• For diagnosis of right ventricular STEMI, right-sided leads V4R should be placed

Subacute Inferior Posterior Lateral STEMI

• Sinus Rhythm
• Inferior STEMI
• ST Elevations (II, III, aVF)
• ST Elevation III > II
• Lateral STEMI
• ST Elevations (V5-V6)
• Posterior STEMI
• ST Depression in V1
• It is a subacute STEMI because, in addition to ST elevations, Q wave formation is already occurring
• High reciprocal R wave in lead V1
• There would be a pathological Q wave in the posterior leads
• The patient had proximal occlusion of the dominant right coronary artery