ST Segment – The Thing You Can’t Miss Nick Sparacino Cardiology Study Group

ST Segment J-Point to beginning of T wave Isoelectric in limb leads in 75% of “normal” EKG Up to 90% of all EKG’s have some ST elevation precordially >1mm elevation abnormal Any depression abnormal

Baseline? I don’t need no stinking baseline! Three potentially isoelectric portions PR, ST, TP PR can be unreliable, particularly if pericarditis is on differential Generally use TP None can be completely relied on with standard EKG

Mechanism of ischemic/injurious ST Changes 2 “phases” of electrical activity Ischemic tissue depolarizes and repolarizes less vigorously than healthy tissue

How does that make the squiggly line change?

Location, Location, Location

Where’s the lesion?

Where’s the lesion?

Where is the lesion? What is your mgmt?

Early Repolarization Traditionally considered benign 1-5% of general population More common with young males, African Americans Large T waves, concave ST contour, no other evidence of LVH or other causes Mimics hyperkalemia 2008 NEJM found 2.1 HR for SCD!

Early Repolarization

LVH Covered in last installment High points: Estes-Romhilt is best criteria Look for big QRS, negative P in V1, clinical history of htn, stim abuse

Digoxin Derangements in Na/Ca movement produces changes in action potential Causes characteristic “scooped” inverted ST-T Looks like check-mark

Wellen’s Sign 1996 Wellen described a series of acute proximal LAD lesions with no ST elevation or troponin rise Biphasic anterior T waves the only unifying feature A case was missed by one of us at the VA recently – can’t lean on trops!

Pericarditis Diffuse ST elevation Look at PR interval!

What do you do?

Brugada Most well known of a series of inherited ion channel pathologies Produce a characteristic pattern of precordial ST elevation 3 described types, type 1 is the classic Very high J point, smoothly descends to an inverted T High risk of sudden cardiac death Most common in southeast Asian males – up to .5-1% in a Japanese study

Neurologic insult Most often described with strokes Trauma, tumor, metabolic derangements

When in doubt Call for help! Fellow residents, senior residents, chiefs, fellows, IM attendings, cards attendings “Better to wake someone up than put someone to sleep” Practice!

Over to you, Mo www.goodsamcsg.wikispaces.com Cardiostudy@gmail.com Powerpoints, articles, calculators, Oh My! EKG reference cards