2nd Degree AVB Type I? Or something else?

[akroeze]

http://newacp.blogspot.com/2009/06/2nd-deg...i-with-bbb.html

Ok so I had this all typed up and somehow lost the entire post so I'm going to type it up again somewhat more short this time.Elderly female patient presenting to the local ED with 2-3 weeks of general weakness and presyncopal episodes. I encounter this patient as I take over her care for the trip from the local ICU to the tertiary care facility for pacemaker insertion. V/S are stable, no complaints when I cared for her.

No 12 lead available (it was on her chart so I didn't do my own). I tried as best as I could to clean it up but that was the best tracing I could do no matter what I tried.

(Can't get images to post even though the blog post before this it went just fine. Now when I post them it doesn't let you click to enbiggen.)

http://picasaweb.google.ca/lh/photo/eROyci...feat=directlink

http://picasaweb.google.ca/lh/photo/E1l29Q...feat=directlink

Physician's diagnosis? 2nd degree AVB Type I with RBBB

If I hadn't been told that I don't know that that is what I would have come up with on my own. Before my post was eaten I had gone into great detail about my step by step interpretation but I'll summarize it this time.

Regular at a normal rate with variance between wide and narrow QRS complexes. The P-waves seem to be associated to the QRS variable between a very prolonged PRI to a normal PRI. The normal PRI is attached to the narrow complex and the prolonged PRI is attached to the wide QRS.

Can BBBs be intermittent like that? To the point of the bigeminy that is shown at the end of the strip there? One could actually argue that there are three different morphologies that are rotating through at the end not two, although I think the third one is a fusion of the other two (it looks like half of one and half of the other). The QRS are regular regardless of the morphology yet the PRI flip flops, how is this possible? Can someone who knows more about this stuff answer how all this is possible?

[chbare]

Hard to tell with what I see. The baseline is fairly rough and it is difficult to identify P waves. In addition, differentiation of RBBB versus LBBB without a XII lead is difficult, along with axis, or the determination of fascicular blocks. Large Q waves in the the inferior leads are highly suggestive of an old MI. Clearly, inferior wall (RCA) pathology can definitaly lead to SA node dysfunction and AV blocks, along with atrial fibrillation. These could even be escape complexes with an underlying AV block, or we could even be looking at sick sinus syndrome.

The patient did not have a pacemaker place at the time of this ECG?

Take care,

chbare.

[akroeze]

No pacemaker in place at the time of the ECG. She was being observed in ICU due to the block diagnosis but had required no interventions. She was going for a permanent pacer insertion as it was presumed her presyncopal episodes were due to bradying down or going to a higher degree block transiently.

[Jeepluv77]

So I'm not doctor, but I don't get how that could be a second degree type anything. I didn't see one single dropped beat. What i did see was p few p waves but others were indiscernable and a regular r-r with wide qrs and two conducted PAC's. It looks like a junctional rhythm to me coming from low in the junction. The p waves that are visible seem to be kind of haphazardly strewn around like the SA node is just firing whenever it feels like it. Just my interpretation, but I really don't see any 2nd degree of any sort in there.

[medic82942003]

same here no second degree.

[chbare]

An underlying AVB is possible; however, it could be obscured by an escape rhythm.

Take care,

chbare.

[akroeze]

Thoughts on how the morphology rotates between three different ones in order at the end? And how the one seems to be a fusion of the other two?

[crotchitymedic1986]

chbar raised a good point. I once almost called a rhythm 3rd degree which was really 2nd type 1, but the pacemaker was firing so no beat would drop (pacemaker spike not discernable in rhythm).

I think what we are seeing as Ps are actually Ps, the rhythm is to regular for fib.

Unless the pacemaker spike is not discernable here, i would say this in not wenkebach.

In one of the strips, you can measure a p at the top of every T wave (lead 3), but in other strips the p waves have no correlation with the QRS, so I think the patient is going back and forth between 2nd type 2 and 3rd degree.

[Tom B.]

chbare asked the right question. Is this paced? That's the first thing to rule out (and it's easy to look for a pacemaker pocket).

Since it isn't paced, I'm going to fall back on one of the most basic and important rules of electrocardiography. Wide QRS complexes are ventricular until proven otherwise. Now throw in occasional fusion complexes and it's double-plus ventricular until proven otherwise (that was for all you George Orwell fans out there).

The wide complexes show an important abnormality (this has to be taken with a grain of salt because we're in monitor mode but it's still concerning). They show inappropriately concordant ST segments and T-waves (i.e., acute injury pattern).

If I may make a friendly suggestion, you might want to consider changing your default leads to include at least one reciprocal lead (my recommendation would be lead aVL because it's the most sensitive). Monitoring leads II, III, and aVF puts all of your eggs in the "inferior" basket and it's a little bit redundant.

Assuming that lead I shows an upright QRS complex and lead V1 shows RBBB morphology (a guess based on what you said regarding the physician interpretation) then the wide QRS complexes probably show bifascicular RBBB/LAFB morphology, which means the escape rhythm probably originates near the left posterior fascicle of the left ventricle. That's just gee-whiz information, and irrelevant to the question of what the heart rhythm is (some type of supraventricular rhythm with accelerated idioventricular rhythm and then ventricular bigeminy).

Interesting rhythm strip!

Tom

[akroeze]

So we have two different interpretations. I personally was leaning towards the 2nd degree Type II/3rd degree flip-flop but what chbare said has lots of merit too. Just goes to illustrate that nothing is certain in this field.