Regarding Cardiac CTA and Lopressor?

[DutchgirlRN]

I work in Medical Imaging. Our cardiology groups protocol for Cardiac CTA's is Lopressor 15 mg IVP over 8 minutes. Wait 15 minutes and if the HR continues to be >60 give an additional 35 mg IVP over 7 minutes. Is this common?

I don't have a problem pushing 50 of Lopressor but what jerks my chain is that invariably the intial 15 mg will get the patients heart rate down close to 60 bpm (we don't give it unless they start out under 80 bpm) but if the HR is say 62 the cardiologist insists the other 35 mg be given and very rarely does that additional 35 mg do anything. There have been several occasions when the patient was fine but within minutes after the scan their HR and BP bottoms out. I had one patient that went down to 52 bpm and they still wanted additional Lopressor given. I did give it, very slowly and checked the BP Q min. The patient went down to 36 bpm when holding their breath during the scan and I was holding my breath also.

Is there a better way to use Lopressor? Use a different medication? I wouldn't dare suggest something different to one of the cardiologists, I need my job, but I would be interested to know what others are doing. I may be able to suggest something to one of the PA-C's.

Also why do we hold the Lopressor when the P-R interval is over .26? Just curious.

Thanks~

---

Members don't see this ad.

 

[howelljolly]

Also why do we hold the Lopressor when the P-R interval is over .26? Just curious.

Thanks~

I dont know the answer to any of your questions except this one.

Lopressor slows the conduction through the AV node. If the patient already has a 1st degree AV block (PR interval > 0.26), they might not be able to tolerate the additional slowing of conduction and thereby worsening the AV block.

 

[DutchgirlRN]

I dont know the answer to any of your questions except this one.

Lopressor slows the conduction through the AV node. If the patient already has a 1st degree AV block (PR interval > 0.26), they might not be able to tolerate the additional slowing of conduction and thereby worsening the AV block.

.....ahh, that makes sense. Thanks for explaining

 

[dragonfly99]

I believe it is common to try to lower the HR to <60 for doing cardiac CT scans, and I believe for MRI also. Otherwise you don't get a good (readable) scan. Heart rate in the 50's or even 40's shouldn't be a problem if the patient's BP is OK and asymptomatic. If you're having a lot of problems with patients bradying to the 30's and being hypotensive, then maybe the protocol needs modification...you could post in radiology forum to see if any of them have comments about protocol(s) used at their med centers for doing CTA or MRI and how much beta blocker is given prior. There might not be a lot of radiology residents or cardiology fellows who know the exact doses in the protocols though...we aren't usually the ones setting up those types of protocols.

 

[drdavemd]

Low HR helps to improve the likelihood of getting a diagnostic study. This is important for MR and for 64 slice and fewer CT scans. For 256 or 320 slice CT this is less of a problem since the entire heart can be imaged in a single cardiac cycle as a volume.

We do not always use bblockers prior to CT here.

There are myriad drugs and ways to administer them to lower the HR and as one of my mentors tells me, "If there was one right way to do something, we would all do it that way."

Sorry if the Cardiologists at your institution are not open to suggestions, but my approach would be to gather data about how often you experience HR/BP problems, the consequences of the problems, and what drugs were given to cause the problem. Hopefully people will be open to suggestions accompanied by data.

 

[lurkerboy]

That is a lot of IV metoprolol to give at once. We have a protocol that has us give 5mg IVP and we repeat q5-10m. If after 20mg total the HR is not close enough to 60, we give 5-10mg of diltiazem. We prefer when the patients are premedicated with oral BB prior to the CT (like 50mg PO a few hrs before the study).

The studies get exponentially ugly as the HR rises above 60bpm. HR of 40-50 is OK as long as its temporary.

I work in Medical Imaging. Our cardiology groups protocol for Cardiac CTA's is Lopressor 15 mg IVP over 8 minutes. Wait 15 minutes and if the HR continues to be >60 give an additional 35 mg IVP over 7 minutes. Is this common?

I don't have a problem pushing 50 of Lopressor but what jerks my chain is that invariably the intial 15 mg will get the patients heart rate down close to 60 bpm (we don't give it unless they start out under 80 bpm) but if the HR is say 62 the cardiologist insists the other 35 mg be given and very rarely does that additional 35 mg do anything. There have been several occasions when the patient was fine but within minutes after the scan their HR and BP bottoms out. I had one patient that went down to 52 bpm and they still wanted additional Lopressor given. I did give it, very slowly and checked the BP Q min. The patient went down to 36 bpm when holding their breath during the scan and I was holding my breath also.

Is there a better way to use Lopressor? Use a different medication? I wouldn't dare suggest something different to one of the cardiologists, I need my job, but I would be interested to know what others are doing. I may be able to suggest something to one of the PA-C's.

Also why do we hold the Lopressor when the P-R interval is over .26? Just curious.

Thanks~

 

[dragonfly99]

I like DrDave and Lurkerboy's suggestions. I agree that sounds like a lot of IV metoprolol to give at once...especially the 2nd slug. I've never given 35mg all at once, even on the hospital floor, since people are just so different in terms of what they respond to. It sounds like maybe your protocol just needs some rewriting...