A COMPARATIVE EVALUATION OF VASCULAR CLAMPS

VOLUME 44 NOVEMBER 1962 NUMBER 5

Thoracic and Cardiovascular Surgery

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A COMPARATIVE E V A L U A T I O N OF VASCULAR CLAMPS Grant A. Hickman, M.D. (by invitation),

and JD Mortensen,

M.D.,

Salt Lake City, Utah

S

INCE the introduction of Potts' fine-toothed vascular clamp in 1948,4 a number of additional " a t r a u m a t i c " vascular clamps have been developed and have appeared on the surgical instrument market. Surgical literature does not contain an adequate objective evaluation of these clamps or reports of any comparative investigatioti of their advantages and disadvantages. This study was therefore undertaken to provide an objective comparison of the characteristics and performance of various vascular clamps currently available in American surgical supply houses. Vascular clamps are used to occlude blood vessels safely and reliably without causing significant trauma to the vessel wall. Therefore, an-adequate evaluation of such clamps must include investigation of three parameters of their function, namely: (1) occlusive ability of a clamp—or its effectiveness in overcoming intraluminal fluid pressure; (2) holding ability—or the clamp's maneuverability without slipping when applied to a transected blood vessel; and (3) atraumatic characteristics—or the ability of a clamp to occlude a vessel lumen without injuring its wall. Suitable methods of evaluating each of these factors have been developed and standardized. This report records the results of these objective evaluations of the characteristics and performance of sixteen different, currently available, vascular clamps (Table I ) . These clamps can conveniently be divided into three groups according to the type of occluding surface the clamp exhibits to the blood vessel. First are the fine-toothed (Pig. 1, A) clamps which From the Experimental Surgical Laboratory, Latter-day Saints Hospital, and Rumel Chest Clinic, Salt Lake City, Utah. Read at the Forty-second Annual Meeting- of The American Association for Thoracic Surgery at St. Louis, Mo., April 16-18, 1962.

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achieve their atraumatie characteristics by rows of tiny teeth which do not occlude with each other in holding the blood vessel. In this group are the Potts, Green, Senning, Muller-Markham, and Wylie 5 clamps. The second group (Pig. 1,5) are clamps which have serrated teeth that either partially occlude or interdigitate to achieve their atraumatie characteristic. The atrau-grip jaw is the

Fig. 1.—Types of vascular clamps tested. A, Example of a flne-toothed vascular clamp (Potts patent ductus clamp). B, Example of a serrated vascular clamp (Glover atrau-grip). C, Example of an occlusive vascular clarnp (Satinsky vena cava clamp).

prototype for these clamps and has been made into various types of clamps such as the Glover clamp, the Bailey (fenestrated) clamp, and the DeBakey (peripheral vascular) clamp. Another serrated clamp utilizes the Kapp-Beck serration. The third group (Fig. 1, C) of clamps depend on occlusive apposition of the clamp jaws and utilize various types of mechanical features to prevent trauma. The Blalock clamp with the screw type of occluding mechanism is one such example which we tested. The Satinsky vena cava clamp is another

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Vol. 44, N o . 5 November, 1962

and the more recently developed Brown clamp, which is covered with foam rubber, is a third example. Many surgeons still use the rubber-shod intestinal clamp on blood vessels, so it was included in this study for comparative purposes. The Bainbridge, Crafoord, and Johns Hopkins clamps are other occlusive types of vascular clamps which we studied. TABLE I. A. FINE-TOOTHED C L A M P S

|

Potts Green Senning Muller-Markham Wylie

T Y P E AND N A M E OF CLAMPS B. SERRATED C L A M P S

Glover (atrau-grip)

TESTED |

C. OCCLUSIVE C L A M P S

Blalock Satinsky

Bailey (fenestrated, atrau-grip)

Brown

DeBakey (peripheral vascular, atrau-grip)

Rubber-shod (intestinal)

Kapp-Beck

Bainbridge Crafoord (cloth covered) Johns Hopkins

METHODS AND RESULTS

Occlusive Experiments.—In order to test the effectiveness of each clamp in occluding a vessel lumen at various intraluminal pressures, a segment of normal thoracic aorta was removed from a recently autopsied dog. After rinsing the aortic segment in physiologic saline solution and ligating its intercostal branches, a glass cannula was tied securely in one end and this was connected to a reservoir of saline which could be forced into the vessel under measured pressure (Fig. 2). The clamp to be tested was then applied 5 mm. from the open end of the vessel and the saline was allowed to fill the vessel under rising pressures until leakage at the clamp was observed. This was repeated at least three times at each click of the lock in order to determine the range of occlusiveness provided by the clamp at all settings of its lock. Results showed a wide variation in occlusive ability among the clamps tested (Table I I ) . There was no clear-cut superiority for any of the three general types of clamp so far as occlusive effectiveness is concerned. Fifteen pounds per square inch of intraluminal fluid pressure (about 700 mm. Hg) was held without leaking by ten of the clamps tested, namely, the Potts, Senning, and Wylie fine-toothed clamps, all clamps with the atrau-grip serration, and the Blalock, Bainbridge, Crafoord, Hopkins, and Satinsky occlusive clamps. At minimum lock settings, only the Satinsky clamp did not leak at 15 pounds of intraluminal pressure, this being the most effective clamp on the occlusive test. The least effective clamp for occlusion was the Green clamp which permitted leaking at under 10 pounds per square inch pressure when fully closed. When fully closed, none of the clamps tested leaked at physiologic pressures. The six best performers on these occlusive tests, in order, were the Satinsky, Bainbridge, Crafoord, Johns Hopkins, Wylie, and Glover clamps.

H I C K M A N AND MORTENSEN

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TABLE I I .

RESULTS OF OCCLUSIVE

J. Thoracic and Cardiovas. Surg.

EXPERIMENTS

I N T E A L U M I N A L PRESSURE CLAMP

A. Fine-toothed

clamp

Potts Green Senning Muller-Markham Wylie B. Serrated clamp Glover Bailey

(feaestrated)

DeBakey (peripheral vascular) Kapp-Beck C. Occlusive clamp Blalock Satinsky Brown Rubber-shod (intestinal) Bainbridge Crafoord (cloth covered) Johns Hopkins

LOCK SETTING

Minimum Maximum Minimum Maximum Minimum Maximum Minimum Maximum Minimum Maximum Minimum Maximum Minimum Maximum Minimum Maximum Minimum Maximum Minimum Maximum Minimum Minimum Maximum Minimum Maximum Minimum Maximum Minimum Maximum Minimum Maximum

CAUSING L E A K I N G

4.5 1.5 7.5 5 2.5 13 2

5 1.5 1.5

—

2.5 13 -.0.5

-

3 13 2 12 13 12

-

11

(LBS./SQ. IN.)

MAXIMUM W I T H O U T LEAK

4 15 1 7 4.5 15 2 12 1 15 4.8 15 1 15 1.0 15 2 12.5 0.25 15 15 2.5 12 1.5 11 12 15 11 15 10 15

RANK

7 16 5 14 4 5 8 8 12 10 1 13 15 2 3 4

Holding Ability.—This characteristic was evaluated by applying the clamp carefully 5 mm. from the end of a freshly cut segment of fresh dog aorta which had been cleanly stripped of loose areolar adventitial tissue (Fig. 3). Thickness of the wall and condition of its outer surface was kept as near constant as possible for all tests. With the clamp actually in place at the degree of tightness of the lock to be evaluated, horizontal traction on the vessel was applied at measured amounts of force which was gradually increased until the vessel slipped through the jaws of the clamp. While traction was being applied to the vessel, the clamp was accurately supported with horizontal counter-traction which avoided interference or augmentation of its holding ability. Each test was repeated three times at each lock setting of each clamp. The method seemed reliable since there was a clear-cut end point and the results were readily reproducible. Findings (Table III) indicate important differences in holding ability of the clamps tested. Most noteworthy is the ease with which all the smooth-jawed occlusive clamps (except the Satinsky and Bainbridge clamps) slipped. Even the powerfully occlusive Blalock clamp slipped quite easily. In general, the serrated clamps proved most reliable and resistant to slipping on

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VASCULAK CLAMPS

F'S- 2.—Method of testing- occlusive ability of vascular clamps.

Fig. 3.—Method of testing- holding ability of vascular clamps.

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HICKMAN AND M O E T E N S E N

traction. The fine-toothed clamps all performed well on this test also. At the first lock setting only the atrau-grip clamps (Glover and Bailey) and the MullerMarkham clamp reliably prevented slipping. TABLE I I I .

R E S U L T S OF TRACTION

EXPERIMENTS

POUNDS OF TRACTION CAUSING SLIPPAGE MINIMUM

Fine-Toothed

Potts

Clamp

Green Senning Muller-Markham Wylie Serrated Clamp Glover Bailey (fenestrated) DeBakey (peripheral vascular) Kapp-Beck Occlusive Clamp Blalock Satinsky Brown Rubber-shod (intestinal) Bainbridge Crafoord (cloth covered) Johns Hopkins

LOCK

SETTING M A X I M U M LOCK SETTING

2 1 2 3 2

6 5 6 7 5

5 12 5 3 8

3 3 1-%

9

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6

2 1 10

2

6

5

%

% %

4 7 2

%

14 9 15 16

2 1

8 6

4 12

1

5

11

i-%

It is important here to note that an important factor relative to slipping from traction is the wall thickness of the vessel clamped. Relatively thick-walled aorta or larger arteries are held easily by most of the toothed and serrated clamps whereas small arteries and veins slipped through all but the atrau-grip clamps unless the higher lock settings were used. The highest ranking clamps on these traction experiments were those with the atrau-grip serrations, then came the Muller-Markham, Bainbridge, Potts, Senning, and Kapp-Beck clamps, in order. Trauma Experiments.—Trauma to the vessel wall produced by vascular clamps was assessed both by gross and microscopic examinations. Two groups of experiments were carried out: In the acute experiments the thoracic aorta of anesthetized dogs was exposed and the pleura and areolar adventitial tissue was gently removed as would be done for a vascular anastomosis. The clamp was applied at the desired lock setting, was left in place without disturbance for 30 minutes, and was then removed, allowing blood to flow through the previously clamped area for 2 hours. The animal was then killed and the aorta promptly removed and examined. In the second group of trauma experiments, each clamp was applied to the aorta for 30 minutes, then removed, the chest closed, and the dog was allowed to recover. Seven to 10 days later the animal was killed and the aorta was removed and examined. The same type of examination was carried out in both the acute and chronic experiments. The degree of gross change visible, both on the intimal and adventitial surfaces of

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Pig. 4.—Grades of gross pathologic changes caused by vascular clamps, a, Minimal (1+) gross change consisting of simple creasing of the intima. b, Mild (2+) gross change—mild intramural hemorrhage or ecchymosis. c, Moderate (3+) gross change—marked intramural ecchymosis and minimal intimal disruption, d. Severe (4+) gross change—complete intimal disruption and at least partial disruption of media.

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Fig. 5.—Grades of histologic changes caused by vascular clamps. a, Minimal (1+) change—edema, deformity, and atrophy of collagen and muscle fibers in the media, b, Mild (2+) change—collagen fiber degeneration and focal inflammatory cellular exudate. c, Moderate (3+) change—extensive inflammatory exudate, intimal disruption, and slight disruption of media fibers, d, Severe (4+) change—disruption of intima and most or all the media.

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the vessel at the clamp site, was assessed and graded from 0 (no change visible) to 4+ (actual disruption of the mural integrity) (Fig. 4 ) . Histologic evaluation of the vessel wall was carried out by qualified pathologists utilizing both hematoxylin and eosin stains, as well as the elastic van Gieson preparation. Here also (Fig. 5) the degree of change was graded from 0 (no recognizable change) to 4+ (disruption of mural integrity). The degree of trauma to the vessel wall caused by some of these so-called atraumatic vascular clamps is rather startling. Little or no immediate clinical effect would be expected from grades 1 and 2 trauma, but the late effects of even this small amount of trauma on the development of localized degenerative changes must be considered. Certainly grades 3 and 4 trauma may be expected to cause clinical problems which include disruption, hemorrhage, thrombosis or embolization, and aneurysm formation. Results of the trauma experiments (Table IV) are the most clear-cut in this study. One clamp (the Brown 1 sponge rubber-covered clamp) caused no trauma at all and four (the rubber-shod, Potts, Green, Senning) clamps caused negligible trauma. Another group of clamps (the Wylie, Muller-Markham, cloth covered Crafoord, Satinsky, Johns Hopkins, and all atrau-grip clamps) are relatively atraumatic when locked gently, but are capable of causing serious trauma when fully clamped and locked. The Blalock and Bainbridge clamps can cause serious trauma if tightened without caution since they are so powerfully occlusive. TABLE IV.

R E S U L T S OF TRAUMA E X P E R I M E N T S TRAUMA PRODUCED

CLAMP

M I N I M U M LOCK SETTING

M A X I M U M LOCK SETTING

RANK

Potts Green Senning Muller-Markham Wylie Glover Bailey (fenestrated) DeBakey (peripheral vascular) Kapp-Beck Blalock Satinsky Brown Rubber-shod (intestinal) Bainbridge Crafoord (cloth covered) Johns Hopkins

0 0 0 1+ 0 1+ 1+ 1+ 1+ 2+ 1+ 0 0 2+ 1+ 1+

1+ 1+ 1+ 2+ 2+ 3+ 3+ 3+ 3+ 4+ 3+ 0 1+ 3+ 2+ 3+

2 2 2 7 6 9 9 9 9 16 9 1 2 15 7 9

DISCUSSION

These experiments demonstrate that all the features of an ideal vascular clamp are not incorporated into any one clamp. Several clamps commonly used for vascular work have little to recommend them since they do not rank high in any of the tests utilized. It behooves a vascular surgeon to become thoroughly aware of the limitations and disadvantages as well as the particular values of

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the clamps he uses. This will enable him to choose the best possible clamp for each situation—in all instances selecting the least traumatic clamp which will provide adequate occlusion and maximum safety from slippage. SUMMARY AND CONCLUSIONS

1. Sixteen currently popular vascular clamps have been tested in the laboratory, with a comparison of their performance in three ways: (1) occlusive ability, (2) freedom from slipping, and (3) trauma produced. 2. No one clamp is superior to the others in all respects; each clamp has particular values, hazards, and limitations. 3. Clamps ranking high for general vascular work which produce relatively mild trauma while performing acceptably in regard to holding and occlusive ability include: the Potts, Senning, and Muller-Markham fine-toothed clamps, the Glover and Bailey (atrau-grip) serrated clamps, and the Satinsky occlusive clamp. The Brown sponge rubber-covered clamp is remarkably atraumatic but ranks rather low on holding and occlusive ability. REFERENCES 1. Brown, L.: A Vascular Clamp Utilizing Sponge Rubber, A. M. A. Arch. Surg. 83: 177, 1961. 2. Egdahl, R. H . : A Simple Clamp for Arterial Anastomosis, Am. J . Surg. 9 1 : 113, 1956. 3. Henson, C. F., and Rob, C. G.: A Comparative Study of the Effects of Different Arterial Clamps on the Vessel Wall, Brit. J . Surg. 4 3 : 561, 1956. 4. Potts, W. J . : A New Clamp for Surgical Division of the Patent Ductus Arteriosus, Northwestern Univ. M. School Quart. Bull. 22: 321, 1948. 5. Wylie, E. J . : A New Aorta Clamp, Surgery 36: 781, 1954. (For Discussion,

see page

633)