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My Involvement with Intracranial Aneurysms

Milton D. Heifetz, MD
Milton D. Heifetz, MD
Clinical Professor of Neurosurgery
University of Southern California
Visiting Professor of Neurosurgery
Harvard Medical School
AANS Member Since 1961

Intracranial Aneurysm Clip System
Fig. 1 Intracranial Aneurysm Clip System

Development of Micro-Instruments
Fig. 2 Development of Micro-Instruments

Development of Micro-Instruments
Fig. 3 Development of Micro-Instruments

My involvement with intracranial aneurysms was sparked in 1950 when I sat in the operating room cutting a rectangular piece of metal out of a sterile sheet of tantalum. This was then bent into a "U" shape and applied over an aneurysm with a straight Kelly forcep.

The actual development of the Heifetz aneurysm clip system began in 1962. The standard aneurysm clips used at that time were the Mayfield spring clip and the Olivecrona malleable clip. Although the Mayfield clip was an excellent improve-ment upon previous clip designs, I was impressed with the need to solve several technical problems related to the spring clip. These included the need to reduce the possibility of the clip to slide off the aneurysm neck; the possibility of lacerating the neck and thereby avulsing the aneurysm off of its parent artery, and finally to improve the spring action so that it does not lose its compressive force after the clip is fully opened more than once.

I was convinced that clip slippage, aside from the blade's compressive force, was due in some cases to pressure against the protruding back end of the clip by the brain as it returns to its normal position after retraction and secondly to the lack of significant friction between the clip blade and the aneurysm tissue.

It would be ideal if there were no back end to an aneurysm clip. To reduce the length of this protrusion, I was forced to consider an internal coiled spring similar in principle to a woman's hair clip. This approach also solved the problem of spring fatigue. With a coiled inner spring, the clip could be opened repetitively without loss of its compressive force. To further limit the tendency of the clip to slip, I added a corrugated design to the inner surface of the clip blades which enhanced its holding power.

The problem of avulsing the neck of an aneurysm when the neck is very delicate and traction is applied against it as the clip blades close, was partially solved by changing the contour of the clip blades. Biconvex blades were formed which reduced the puckering and tension upon the junction of the aneurysm and its parent artery. This concept of blade design, the contour and serrations, was subsequently adopted by Frank Mayfield and Thoralf Sundt in the design of their clips. To further reduce the tearing tendency and cutting tendency of the blades, a space of 0.03 mm. was engineered between the mid-portion of the blades.

To enhance visualization of the clip during its application, the point of attachment of the clip appliers was placed as proximal as possible on the back end and the width of the clip appliers was designed to be no wider than the width of the aneurysm clip.

Since the development of the Heifetz Clip System, I continued to be involved with aneurysm clip technology. I was privileged to help Frank Mayfield in 1965 to improve his aneurysm clip appliers and thereby prevent the undue rotation of the Mayfield clip within the appliers. I subsequently was asked by William Scoville if I could help improve his ingenious edge wound Scoville clip which had the wonderful attribute of a very small back end. The workable modifications I made for him were unfortunately never utilized by the manufacturer. Further involvement included design discussion with Sean Mullan and Al Rhoton. My involvement continues.

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