Simplified normal heart weight scaleEditor - We found the article entitled "Derivation of new reference table for human heart weights in light of increasing body mass index", written by Gaitskell et al, extremely interesting.1 Postmortem heart weight is important in diagnosing whether the heart is normal. In this article, the author described that heart weight (HW) correlated slightly better with body surface area (BSA) than body weight and presented new reference chart. However, in 1999 we already reported that HW correlated better with BSA than body height (BH) or body weight (BW) based on forensic autopsy cases.2 Furthermore, for practical use we developed a simplified scale with which normal HW could be easily and quickly calculated from BH and BW.2 Although Gaitskell et al used the 384 adult autopsy cases without evidence of macroscopic or microscopic heart or lung disease, we thought that using forensic autopsy cases dying from unnatural causes was adequate for analysis. Furthermore, we excluded the cases with systemic disease that were commonly believed to affect HW or those with evidence of heart disease or those with multiple postmortem changes or those with damage to multiple organs. Finally we used the 830 adult and child autopsy cases (506 male and 324 female). In our analysis, HW gradually increased up to a subject age of 30 years but was not correlated with age thereafter. However, throughout the age, the log HW and log BSA were strongly correlated in both males (r2=0.884) and females (r2=0.878) with allometric relations: HW=BSA1.441 x 168.20 in males; HW=BSA1.367 x 161.97 in females. Because sufficient large samples were selected under the careful criteria, we thought that the result had great accuracy. Measurement of total HW, which is a valid method at autopsy, has to be done by simple technique. As the Gaitskell et al suggested the need of user-friendly reference chart, we had also developed a simplified normal HW scale which could be quickly and easily calculated by BW and BH. This scale has been used for routine autopsy for the subjects of any age. Using this scale, we have found that more than 70% of persons with sudden natural deaths had higher than normal HWs.3 This result indicated that the heart was overloaded among persons with sudden natural deaths. Lucas mentioned that ethnic difference was a potential confounder in these studies.4 For a person with a height of 175cm and a weight of 75kg, the HW is calculated as 381.1g in Gaitskell's method, however, as 429.8g in our method. We think the difference is owing to the difference of distribution of body fat. Also, there has been time shift for heart/body ratios with increasing longevity and body mass index. To solve these problems, the formulas for obtaining normal HW by BSA has to be compared between different ethnics. Furthermore, to renew the input of HW and BSA of healthy victims who had died of external causes is needed regularly. The pathologists have to determine whether a given heart is normal size at autopsy. We hope simplified normal HW scale is going to be used over the world based on their own HW and BSA relations. If the formulas are not markedly varied among the different countries in future, it may be useful for pathologists to uniform some of them. References 1. Gaitskell K, Perera R, Soilleux EJ. Derivation of new reference table for human heart weights in light of increasing body mass index. J Clin Pathol 2011;64:358-362. 2. Hitosugi M, Takatsu A, Kinugasa Y, Takao H. Estimation of normal heart weight in Japanese subjects: development of a simplified normal heart weight scale. Leg Med (Tokyo) 1999;1:80-85. 3. Motozawa Y, Hitosugi M, Kido M, Kurosu A, Nagai T, Tokudome S. Sudden death while driving a four-wheeled vehicle: an autopsy analysis. Med Sci Law 2008;48:64-68. 4. Lucas SB. 'Derivation of new reference table for human heart weights in light of increasing body mass index'. J Clin Pathol 2011;64:279-280.
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