Tuesday, April 22, 2008

EKG Du Jour - #4

Another case from the EKG Hall of Fame:
She was 79 and referred for evaluation of an "aortic valve disorder." She was told of a cardiac murmur 6 or 7 years ago, yet had been asymptomatic, without dizziness, shortness of breath, nor loss of conciousness. She did not feel skipped beats and had never had fevers. Her echo one month prior had demonstrated a very mildly stenosed aortic valve with a mean gradient of 12.2 mm Hg and an aortic valve area of 1.64 square centimeters with mild aortic insufficiency and normal left ventricular function. Her only medication at the time of evlauation was hydrochlorothiazide for hypertension.

As part of her workup, an EKG was ordered and is shown below:

Click to enlarge
What is demonstrated on the EKG and how should it be treated?

-Wes

Having fun? Don't miss these other EKG cases du jour: #1, #2, and #3.

9 comments:

Anonymous said...

I see an increased PR interval and what looks like a delta-wave. Maybe 3˚ heart block? It's probably not WPW.

If 3˚ heart block, she would need a pacemaker.

Tom said...

My gut tells me 3rd degree block. The P's appear to march with some appearing in the QRS giving illusion of a delta wave. The atrial rate is definitely faster than the ventricular rate. If I saw this as a night nurse, she would get a call to the MD and a set of pacer pads. And hopefully a pacemaker in the morning.

But somehow it seems too easy considering the other EKGs you've put up...

Daych said...

I think this is 2:1 AV block with ventricular escape beat. I don't think that it is 3rd degree AV block because some of the P waves were followed by QRS complex. If it is 3rd degree there shouldn't be any QRS that follow the P wave.

addictedtoWes said...

i think this is 3degree block. the p waves seems pretty regular and dissociated from the QRS. The ventricular rate is also quite slow. It also looks like QRS alternans as the size, shape and axis changes each QRS beat-most obvious in the rhythm strip of II.
?associated pericardial effusion

Anonymous said...

3rd degree block. Lytes, TSH, angiogram, if normal, pacemaker.

Artemis said...

Mobitz II - second degree block with missed beats and ventricular escape beats. Needs monitored bed and probable pacing to avoid complete heart block.

I think...Consult, Dr. Wes, STAT!
A

DHS said...

if you presume that the thing that looks like a delta wave is actually a superimposed p wave onto the qrs complex, you will find that the p waves are regular. the qrs complexes are regular too, in the short-long pattern - short gap, long gap.

something which would explain all of this would be diagnosis: wenckebach - the first p wave is conducted, the second one is delayed, and the third one (the superimposed one) is dropped. it's a pretty cool ecg - the timing is perfect to make it look like something else completely. I'd do something to try and change the atrial rate to distinguish this from a mobitz II.

DrWes said...

Thanks to all who have ventured a guess on this EKG Du Jour #4. This EKG another cool example of physiology in action.

Now, in dissecting this EKG we note several findings:

(1) The underlying atrial rhythm is sinus.
(2) There appears to be two distinct QRS morphologies that alternate beat to beat
(3) The time interval between the alternating QRS complexes is different.

Now, for purposes of discussion, I am going to call the QRS complex in V1 that is shorter (less negative) than the other QRS complex “Stubby.” Note that Stubby always seems to follow (by about 280 msec) a well-defined P wave. Importantly, the R-R interval preceding Stubby is shorter than the following R-R interval, suggesting the “Stubby” complex is conducted from the atrium.

Next, note the timing between the P waves. There is a subtle difference. Print out the EKG in landscape mode and measure it. Note that the P-P interval with Stubby between the P waves is ever-so-slightly (20-40 msec or so) shorter than the subsequent P-P interval. This is called “ventriculophasic sinus arrhythmia” (my favorite term in all of electrocardiography). Although the exact mechanism of ventriculophasic sinus arrhythmia is not known, it is thought to be caused by carotid baroreceptor-mediated phasic changes in vagal tone. The improved AV transport of blood that occurs when the QRS falls between the P waves stimulates the carotid baroreceptors with increased stretch (better cardiac output) increases vagal tone slightly so that it prolongs the subsequent P-P interval. This is found in instances of high-degree AV block, usually Mobitz II.

Final diagnosis: Mobitz II AV block with Infra-Hisian ventricular (probably septal) escape beats and associated ventriculophasic sinus arrhythmia.

A poor man’s ladder diagram is shown.

Treatment? Even though she was asymptomatic, a dual chamber pacemaker was recommended.

Anonymous said...

keep them coming please