Biomedical subjects
Publications and source records attributed to W W Shaw.
The evolving areas of microsurgery pertinent to hand surgery are briefly described and outlined. The spectacular developments in the recent past are merely glimpses of what may yet be ahead for hand surgery. This is illustrated by a science fiction story of the management of an amputation injury in outer space in which many of the currently evolving technologies are employed.
Safe planes exist for plantar incisions that minimize the possibility of subcutaneous nerve injury and are therefore useful in flap design. Nerve branch orientation in the plantar subcutaneous tissue is specific and guides dissection so as to avoid producing anesthesia in weight-bearing areas. An extensive proximal plantar subcutaneous plexus exists that permits elevation of plantar flaps in a superficial plane. This is due to the major contribution that the dorsal circulation makes to the skin of the plantar surface. The blood supply to the non-weight-bearing midsole area is not from the medial plantar artery exclusively. This is a watershed area with important lateral plantar artery and dorsalis pedis artery contributions as well. It is not necessary or desirable to base plantar flaps on a myocutaneous or fasciocutaneous supply with its required deep dissection. Local plantar flaps can be designed to include sensation and abundant blood supply without the need for "subfascial" dissection. Subcutaneous sensory plantar flaps designed in accordance with these principles promise a more ideal solution for the treatment of plantar defects.
Laser Doppler flowmetry (LDF) is a noninvasive, continuous measure of tissue surface microcirculatory red blood cell (RBC) flux. LDF was calibrated against varying RBC volume fractions and flow rates using extracorporeal perfusion of saphenous island flaps of dogs. The RBC flux was found to be linear with LDF signal. The difference in vascular geometry of the skin appeared to play a minor role in generating the LDF signal compared to changes in the RBC flux. In vivo experiments of varying arterial perfusion pressure, flap venous pressure, and total blood flow of the cutaneous island flap had a linear relationship with LDF signal.
The temporoparietal fascia is an ideal tissue source for free transfer to distant sites where ultrathin coverage is either desirable or mandatory. The fascia's dependable vascular anatomy facilitates the technical aspects of microvascular transfer by means of its large vessels, ample pedicle, and ability to be grafted on either side. Furthermore, this highly vascular tissue is available in surprisingly large quantities, and its donor scar is hidden in the hair. The authors have found this flap useful (1) in covering exposed bone and tendon without adding unwanted bulk, (2) in providing thin flap coverage or lining in major facial reconstruction, (3) in covering vital structures such as exposed nerves and vessels, (4) in providing neovascularity both as a recipient graft bed and for control of chronic infection, and (5) in reestablishing gliding-tendon mechanisms. The authors have successfully employed this free flap in 15 cases which involved deformities of the ankle, foot, Achilles tendon, forearm, hand, nose, and contralateral ear and scalp. Seven cases are utilized to illustrate the broad application of this unique and versatile free flap.
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High-frequency (20 mHz) ultra-sonic Doppler in a pulsed mode rather than continuous mode allows blood flow detection in small arteries using a 1-mm crystal embedded in a silastic cuff. The "probe factor" used to determine flow was first established in an in vitro system and found to be reliable. The probe was then tested in five dogs on the saphenous artery and found to be highly responsive to hemodynamic changes in the pedicle. Finally, in 15 long-term studies of island flaps and free flaps, the probes were implanted to obtain daily readings and then removed at 7 days. Except for some dog-related problems and technical errors, the system produced reliable flow data in the percutaneous cable. It is anticipated that such immediate and direct information on the pedicle blood flow would be useful in monitoring flaps.
Compartmental syndrome is a condition in which swelling within a closed anatomic space increases the intracompartmental pressure to compromise the circulation and function of tissue within that space. Unless this condition is recognized early and treated by prompt surgical decompression, permanent neuromuscular deficits may result. In those instances in which early clinical evidence of this syndrome is difficult to assess, monitoring of intramuscular pressures may be valuable adjunct in the clinical evaluation of patients at risk for this syndrome. The association of compartmental syndrome with a wide variety of circumstances and the importance of an early diagnosis make it essential that all physicians be familiar with this condition. As physician awareness and recognition of this condition increase, the complications associated with it can be greatly reduced.
A review of the current status of penile artery revascularization and its methodology is presented. Microsurgical anastomosis of the inferior epigastric artery or central arteries produces good results in younger men. Older patients or those with diabetes, hypertension or who have had coronary bypass surgery do not appear to have good results.
Three young men with impotence due to a pudendal arteriovenous malformation had a common selective pudendal arteriographic finding of early passage of contrast medium from the bulbar artery region into the venous drainage of the pelvis. Perineal exploration revealed the malformation and correction resulted in significant restoration of erectile capacity. This entity may be a frequent occurrence in young men that may become apparent only when trauma or disease affects the contralateral pudendal artery or its branches.
In the 2 cases reported the rectus abdominis muscle was used as a sling to construct the pelvic floor. In patient 1, a large squamous cell carcinoma of the perineum was treated with an abdominal perineal resection. Reconstruction was accomplished internally using a rectus abdominis muscle sling and externally with a gluteus maximus musculocutaneous flap. In the second case, the rectus abdominis muscle was used as a supportive sling to reinforce a perineal hernial repair and prevent recurrence.
As in other areas of reconstruction, microvascular free flaps have earned a definite role in certain breast reconstructions difficult to accomplish with conventional techniques. With improvements in techniques and survival rates, the advantages of such reconstructions have become increasingly more attractive to the patient and the surgeon.
In using autogenous vein grafts in microvascular surgery, maintenance of compliance at the site of anastomosis is of importance in achieving patency. Using high-frequency, 20 MHz, pulsed Doppler ultrasonography to monitor blood flow velocity through the vein graft, we have evaluated the effects of continuous and interrupted suture technique on anastomotic compliance in vessels less than 1.5 mm in diameter. In 15 dogs, 15 procedures of each technique, using the continuous technique in one limb and the interrupted technique on the contralateral limb, patency rates for both techniques, documented by arteriography, are 100% at a mean follow-up of 11 weeks. There were no significant differences in the blood velocity profile and pulsatility proximally, distally, and at the graft site between continuous and interrupted technique. This study confirms the suggestion that autogenous vein graft has sufficient elasticity to maintain normal arterial blood velocity waveforms.
Laser Doppler flowmetry (LDF) is a noninvasive and continuous method of monitoring dermal blood flow in free flaps. There are two LDFs available for clinical application: the LD5000 Laser Doppler Perfusion Monitor and the Periflux Laser Doppler Flowmeter. Varying degrees of arterial (N = 46) and venous (N = 28) occlusion were induced in saphenous island flaps of the dog, while simultaneous measurements with the LD5000 and Periflux LDFs were made. The millivoltage output of both the LD5000 and the Periflux showed a high degree of correlation with arterial and venous occlusion and with each other.
The author's experience with 10 gluteus maximus myodermal free flap breast reconstructions is reviewed against the current methods of reconstruction using silicone implants, latissimus dorsi flaps, regional skin flaps, and rectus abdominis myodermal flaps. The superior gluteal free flap can achieve a reliable, permanent, and aesthetic reconstruction of the breast without silicone implants. The softness, projection, natural appearance, and patient satisfaction are excellent compared with other methods. It is particularly useful in patients who object to the use of artificial implants, are not suitable for regional flaps, or have disappointing results from previous reconstructions. Technical modifications of the flap design and selection of the recipient vessels are important.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.