Question about MIBI scan

Patrick Blanchard said:

Andrew Kerr said:

"Patrick Blanchard, M.D." <blanchard@sonoscore_nospam.com> wrote in
message
news:[email hidden]...

Quoted message said:

On Fri, 05 Dec 2003 22:44:05 GMT, <[email hidden]> wrote:

sometimes, but echocardiography is your best option since it will throw

the

Quoted message said:

questionable MIBI scan into a whole new light. If you do not have LVH,

then

Quoted message said:

you must also consider the absence of a standing hyperventilation ecg as
being an important missing part of the scan. I suspect however, that the
poor protocol of the study will be downplayed by those involved with it.

How do you think a standing hyperventilation ecg would affect the scan
quality, since the tracer is not injected until peak exercise?

I can see a hyperventilation ecg affecting the interpretation of the
stress
ecg (if ST changes are noted on both, for instance), but how would it
affect
the images?

Andrew Kerr M.R.T.(N.)

Hyperventilation can induce coronary vasospasm. Coronary vasospasm is not
always due from atherosclerosis,

However, it often is. There are those who would assert that endothelial
dysfunction is *always* behind coronary spasm even when there is congenital
"bridging."

Quoted message said:

and is often the achilles' heel of
coronary angiography.

Just a little injection of NTG overcomes this "achilles' heel."

Quoted message said:

http://tinyurl.com/xy75

We are discussing the 'scan' and not just the 'images'. The 'scan' includes
the images and the ecg interpretation together. A finding on one can
influence the interpretation of the other. Because of this, it would be
interesting to have the ecg strips and the perfusion images read
independently by different doctors, and see if indeed the two still
correlate.

They typically are read by different observers, Patrick.

Quoted message said:

--
~~~
Patrick Blanchard, M.D., A.B.F.P.
Board Certified in Family Practice
http://www.familydoctor.org/blanchard
~~~
SonoScore
Winning against heart attack and stroke
http://www.sonoscore.com

Is sonoscore.com a new sideline business for you, Patrick?

Humbly,

Andrew

--
Dr. Andrew B. Chung, MD/PhD
Board-Certified Cardiologist
http://www.heartmdphd.com/

"Patrick Blanchard, M.D." <blanchard@sonoscore_nospam.com> wrote in message
news:[email hidden]...

Quoted message said:

On Fri, 5 Dec 2003 18:43:49 -0500, Andrew Kerr <[email hidden]> wrote:

Hyperventilation can induce coronary vasospasm. Coronary vasospasm is not
always due from atherosclerosis, and is often the achilles' heel of
coronary angiography.

http://tinyurl.com/xy75

Unless the patient is actually in spasm at the time of tracer injection,
we're not going to see anything. We had a case like this last summer. The
patient came in with "? Coronary spasm" on his requisition. It was negative.
Then he was admitted a month later and we repeated his scan, injecting when
he had chest pain. It was positive.

Quoted message said:

We are discussing the 'scan' and not just the 'images'. The 'scan'

includes

Quoted message said:

the images and the ecg interpretation together. A finding on one can
influence the interpretation of the other. Because of this, it would be
interesting to have the ecg strips and the perfusion images read
independently by different doctors, and see if indeed the two still
correlate.

It's especially true in the case of small defects. Would the reporting
physician have called it positive if the patient hadn't had ST depression?
Neither of us can answer that. When you have cases where a whole wall is
missing, the ecg isn't really necessary. It's the small defects that can get
us. On the other hand, a really small defect is associated with a small risk
of cardiac event in the next year anyway.

Quoted message said:

Patrick Blanchard, M.D., A.B.F.P.

Andrew Kerr M.R.T.(N.)

Patrick Blanchard said:

MD/PhD said:

Patrick Blanchard said:

<snip>
> Left ventricular size is not going to guide management here, Patrick.

I disagree. It may help identify a false positive for macrovascular
atherosclerosis on his scan.

The "mibi" has already identified normal LVEF so one should not be
expecting
increased LV dimensions, anyway.

OK, I'm leaving my terra firma, but I would like you to clarify this for me
in the perspective of Starling's law. LVEF is a reflection of contractility
of the heart, and not the size of the myocardium.

Correct. However, stroke volume is LVEF times LVEDV (Left ventricular
end-diastolic volume).

SV=LVEF*LVEDV

Resting stroke volume (SV) is largely invariant as is cardiac output (CO) in
the setting of normal heart rate (HR).

Indeed, CO=SV*HR

So going back to SV=LVEF*LVEDV and holding SV=C (ie constant):

LVEDV=C/LVEF

LVEDV is inversely proportional to LVEF.

Normal LVEF suggests normal LVEDV assuming normal heart rate and cardiac
output.

Viola!

Quoted message said:

LVH is a reflection of
the myocardial size, and not of contractility.

LVH on EKG can mean either increased LV size *or* increased LV wall thickness.

However, on 2D echo, LVH only means increase LV wall thickness (ie greater than
1.1 cm).

Quoted message said:

Quoted message said:

Quoted message said:

<snip> 2,3 aVf are isolated for the inferior wall, but I am not certain
what
leads
would become involved with the septum.

Precordial V4, V5, and/or V6 for the inferior septum depending on actual
lead
placement and heart position.

Quoted message said:

>
>>
>> >
>> > Overall, does my cardiac picture look bad? Is this something you
>> > would find on an otherwise healthy 43 year old, the ones who just
>> > never had the test done in the first place?
>>
>> First of all, do not panic. Do not make a hasty decision. Learn about
>> your
>> options first.
>>
>
> Good advice.
>
>>
>> >
>> > If it is suggested do you think I should follow up with a cath or
just
>> > toss it up as being a false positive and check again in 10 years?
>>
>> Neither.
>>
>
> Discuss it with your doctor.

Or with us.

We aren't his doctors, Patrick.

No we are not, and I should have stated "and with us at SMC" instead. Thank
you for clarifying this; it is quite important.

No problem, Patick. You are technically still a "newbie" Usenet doctor :-)
Although, I must say you are catching on fast.

Humbly,

Andrew
--
Dr. Andrew B. Chung, MD/PhD
Board-Certified Cardiologist
http://www.heartmdphd.com/

For those interested here were my cardiologist recommendations:

Do a stress echo to see if it correlates with the mibi although the
general feeling is that the original test is non specific and likely
falsely positive based on my symptomatology. Also to start statins,
weight loss, exercise ect. Watch salt intake. He didn't seem to
concerned.

Thanks for all who wrote suggestions. It was very helpful.

S

Quoted message said:

I just a mibi done. I'm in my early 40's, get only the minority of
chest pain which sometimes I wonder if it's GI related. It's fleeting
and usually very specific to what I would say is my PMI area. I also
have mildly elevated chol and have normal BP. I used to smoke but
quit 15 years ago. There is cardiac history in my family but only in
the 70's.

My Mibi shows an "area of concern." My doctor sent me at my request
because I wanted a stress test before I start exercising again since
it's been a few years.

My main question is, how accurate are these? I really don't want to
have a cath which I assume is the next step.

Thanks