Consequences of pruning in morphometry of coronary vasculature.

There is a paucity of data on the branching pattern and dimensions of the blood vessels in various organs. The reason for the paucity is undoubtedly the tremendous effort needed to obtain the morphometric data. For those organs whose morphometric data have been determined, pruning was introduced: cutting off branches at successive generations, measuring what remained, using the statistical data to estimate what were cut off, and adding the estimated data to the measured data to obtain the final results. Evaluation of the effects of pruning was not possible, however, because a full set of precise data did not exist. Now a complete set of morphometric data on the coronary arteries is presented by Kassab et al. (8). Hence we are in a position to evaluate pruning versus accuracy. Among several pruning protocols tried we found a simple, easy-to-follow scheme that seemed to be reasonable. It reduced the labor by 79% when it was applied to the left anterior descending (LAD) artery of the pig, and it caused the following percentage errors based on comparison with the unpruned data. The largest error incurred in the mean diameters of all orders of tree is 7.6%. The corresponding maximum errors in the length and number of elements in all orders are -9.8% and 30.0%, respectively. The estimated error of the total equivalent Poiseuille's resistance for the LAD artery computed from pruned data was 25.2% when compared with that computed from unpruned data.