Platelets of Mass Destruction

 

By

 

Marc Strassman

Medical Affairs Reporter

Etopia News on Celcast.Biz

www.celcast.biz

 

September 28, 2003

 

Copyright © 2003 by Etopia, All Rights Reserved

 

 

These days, television and the web are full of advertisements urging potential customers of new drugs to "ask your physician about" Drug X, meaning ask them for a prescription for it.  Watching an animated pitch on television for Bristol-Myers Squibb's new anti-platelet-clogging Plavix™, and looking at the same illustration on their website (http://www.plavix.com/DTC/home.html), it seemed to me that the relative size of the blood platelets in the ad was unrealistically big compared to the apparent size of the artery containing them. 

 

I thought maybe they were getting the proportions deliberately wrong for artistic or educational reasons.  In that case, they should have added a warning in the ads:  "platelets and artery not drawn to scale."   But they hadn't.  So I decided, as a reporter, to investigate.

 

At http://www.bartleby.com/107/134.html, I learned that the average red blood cell was only 7.5 x 10-9 m in diameter, with a thickness of 2.0 10-9 m, and that a blood platelet was "much smaller than" that.

 

I needed to know the typical diameter of the relevant blood vessels.  At http://www.medscape.com/viewarticle/409134_3 I learned that:

 

In the LM, mean uncorrected arterial area and luminal area were significantly smaller in women than in men (21.53 vs 26.95 mm2, P < .001; and 15.94 vs 18.79 mm2, P = .020; respectively). The same was true for mean uncorrected LAD arterial and luminal area (14.68 vs 19.94 mm2, P = .002; and 10.13 vs 12.71 mm2, P = .036; respectively).

 

The smallest measurement for any type of average arterial area was 10.3 mm2, for the mean uncorrected luminal area in women in one type of vessel.  The largest was 26.95 mm2, for the mean uncorrected arterial area in men, in another.  Giving Bristol-Myers Squibb the benefit of the doubt, I chose the lowest available average arterial area, 10.3 mm2,

 

A = p r2

10.3 = 3.14 x r2

3.28 = r2

1.8 = r

 

diameter of a coronary artery = 3.6 mm or 3.6 x 10-3 m

 

Here's another source:

 

http://www.medscape.com/viewarticle/418251

 

Clinical Outcome of Stent Implantation in Small Coronary Arteries Using Different Types of Coronary Stent

 

from Journal of Invasive Cardiology

Toshiya Muramatsu, MD, Reiko Tsukahara, MD, Mami Ho, MD, Yoshiaki Ito, MD, Hiroshi Ishimori, MD, Keisuke Hirano, MD, Masatsugu Nakano, MD, Masahiro Matsushita, MD, Wai Yin Leung, MD

Abstract and Introduction

Abstract

Purpose. We evaluated the results of stent placement in small coronary arteries.


Subjects. The subjects were divided into 2 groups: the first contained 911 lesions treated with stenting in the coronary arteries (stent group), and the second contained 1,203 background- and patient-matched lesions treated with balloon angioplasty (POBA group). There was no significant difference in the background of patients or lesions between the groups. A "small coronary artery" was defined as a coronary artery with a reference vessel diameter < 3.0 mm.

 

(For a nice-looking animation about in-stent restenosis, a re-narrowing or blockage of an artery at a treatment site, also featuring larger-than-life blood components [and smooth muscle cells], go to:

 

http://www.fightcoronarydisease.com/resten/resten_01.asp)

 

 

In another study, "small coronary arteries" are defined as those with a diameter of less than 2.75 mm or 2.75 x 10-3 m:

 

http://www.medscape.com/viewarticle/409167

 

Methods: In a prospectively randomized study including 491 dilatations of coronary arteries with a diameter <2.75 mm, additional intracoronary application of dipyridamole was compared with conventional pretreatment consisting of heparin and aspirin.

 

 

Summary:

 

I calculated coronary artery size to be 3.6 x 10-3 m.  One medical study characterized "small coronary arteries" as being 3.0 x 10-3 m or smaller.  Another said that "small coronary arteries" were 2.75 x 10-3 m or smaller. 

 

Let's settle on 3.0 x 10-3 m as a consensus size for coronary artery diameters.

 

3.0 x 10-3 m arterial diameter divided by 7.5 x 10-9 m red blood cell diameter yields a quotient of 4.0 x 105, or, in normal notation, 400,000.  This means that a typical platelet (which is "much smaller than" a red blood cell) has a diameter of, generously speaking, no more than 1/500,000th the width of an ordinary coronary artery, rather than the 1/15th it appears to have in the Plavix animation. 

 

This means that the platelets shown navigating their way through the crowded minefield of a potential customers' crucially-vital interior passageways have been made to look more than 30,000 times larger, relative to the artery, than they really are.

 

This only matters because a worried layperson watching the TV commercial or looking at the web animation on the Plavix site (http://www.plavix.com/DTC/home.html) could easily get the idea that his or her risk of dying from a heart attack is 30,000 times greater than it really is, and will rush to their doctor to unnecessarily demand a prescription for Plavix.

 

It's true, as Bristol-Myers Squibb claims, that "PLAVIX is FDA approved in patients with ACS (unstable angina or non–Q-wave myocardial infarction), whether patients are to be treated with or without PCI or CABG1" 

 

(That's "acute coronary syndrome," percutaneous coronary intervention" and "coronary artery bypass grafting.")

 

See for yourself at:  http://www.plavix.com/HCP/cardio/approves.jsp

 

But with the current trend to the preventive and prophylactic use of powerful, new and expensive drugs (see "Prevention Creep" by Jerry Shine at:  http://www.harvard-magazine.com/on-line/090332.html), which is facilitated by ads in all media that equate self-preservation and love of family with the taking of somebody's new drug, the ability of doctors to prescribe drugs "off-label" once they've been FDA-approved for anything, and the ubiquitous drug salespersons who are the medical equivalent of telemarketers, it's not hard to see how an illustration or animation that depicts the health threat of a problem as being 30,000 times greater than it really is fits into the overall plan.

 

After all, didn't the United States go to war against Iraq on the basis of a military threat that may have been somewhat exaggerated, even if not by a factor of 30,000?  In war and peace, as in drug sales, advertising matters.  A careful citizen/consumer needs to know that he or she is getting the truth from purveyors of products, whether that product is "liberation and democracy" or "platelet.de-cloggers."

 

Of course, all they had to do was add "platelets and artery not drawn to scale" or even just "not drawn to scale," to their television and web advertisements to avoid the taint of dishonesty.  But then maybe fewer people would think they're in trouble that can only be avoided by getting a prescription from their doctor for Plavix.