EKG challange 2

Let's take another look at the rhythm strip. 

This ECG shows 3rd degree AV block with a junctional escape rhythm at 40 beats/min.

Let's march out the P-waves.

When a bradycardia presents with more P-waves than QRS complexes, we know there is a block of some kind.

Because the PR-interval is variable we know this is either 2nd degree AV block type I (Wenckebach) or 3rd degree AV block.

So which one?

With 2nd degree AV block type I there will be clustering of QRS complexes because of the "dropped" P-waves.

This ECG shows a constant R-R interval.Therefore, it is reasonable to assume it is 3rd degree AV block.

So, is the escape rhythm junctional or ventricular?

The QRS complex is "narrow" at 92 ms (0.092 s) according to the computerized measurement.

Hence, it is junctional and not ventricular.

Now let's look at the 12-lead ECG.

This 12-lead ECG shows acute inferior ST-elevation myocardial infarction (STEMI).

Note the ST-elevation in lead II, III and aVF and reciprocal ST-depression in leads I and aVL.

(Note: The precordial leads aren't pretty either. There is subtle ST-depression in lead V2 and R-wave progression is absent in the right precordial leads (V1-V3). The ST-segments and T-waves are flat in leads V5 and V6.)

This 12-lead ECG is also very suspicious for right ventricular infarction because the ST-elevation in lead III is greater than the ST-elevation in lead II.

Regardless, the patient's blood pressure is 80/40 so nitroglycerin is contraindicated.

The patient needs fluid. Lots of fluid!

You might argue that the patient should receive atropine or transcutaneous pacing (TCP).

That might prove to be therapeutic, but it's important to remember that the most important determinant of myocardial oxygen demand is heart rate.

Correcting the heart rate could reverse shock and improve coronary perfusion. Or it could increase myocardial demand to the point where it worsens ischemia/injury.(  hypotension and bradycardia in the setting of acute inferior STEMI is often a manifestation of the Bezold-Jarisch reflex (hypervagotonia))

To me it makes more sense to try fluid first.

The other important thing, of course, is to call a "STEMI Alert" and get this patient to a cardiac cath lab or fibrinolytic therapy depending on transport time!

Remember, time is therapy for STEMI patients!

Treatment:  beginning a fluid bolus with the IV start and early use of atropine (w. the requisite med control), followed by TCP if no effect is seen, and finally dopamine at as low of a dose as I can muster (MAP of 70-80 if I can titrate well enough, higher if she has baseline hypertension)