Biomedical subjects

G I Taylor

Publications and source records attributed to G I Taylor.

At least 19 recordsLinked to original sources

PubMed2000

The angiosomes of the head and neck: anatomic study and clinical applications.

The angiosome concept was introduced over a decade ago by Taylor and Palmer, whereby the body was considered to be composed anatomically of multiple three-dimensional composite blocks of tissue supplied by particular source arteries. Since then, detailed studies of the forearm and leg have been examined by Taylor and his coworkers. This study focuses on another region--the head and neck. Six fresh head and neck cadaver specimens were examined after infusion with a radio-opaque lead oxide mixture and correlated with over 24 previous body studies. The vascular anatomy of the skin, superficial musculoaponeurotic system (SMAS), muscles, brain, dura, and bone was examined. Each layer was painstakingly removed, photographed, labeled, and mapped to the respective arteries and veins. A radiologic subtraction technique was used to allow successive layers to be compared. This information was then scanned into a computer, analyzed, color coded, and labeled, thereby producing a three-dimensional study of the head and neck region to identify the respective angiosomes. As in previous detailed examinations of the leg and forearm, the angiosomes were found to be connected usually within tissues, such as muscle, skin, specialized organs or glands, rather than between the tissues. The muscles usually had vessels of two or more angiosomes supplying them and fell into three major groups based on the similarity of their arterial supply. In some areas, the midline anastomoses were rich, especially in the integument of the scalp, forehead, and lips. In other regions, the midline vascular connections were poor, especially in the tongue and palate. No fewer than 13 angiosomes of the head and neck, supplied by the branches of the external carotid, internal carotid, and subclavian arteries, have been defined, mapping their three-dimensional territories in the skin, the deep soft tissues, and the bones. Although most angiosomes spanned between skin and bone, three territories, those of the vertebral, lingual, and ascending pharyngeal vessels, were confined to the deep tissues without cutaneous representation. Finally, this study provides additional data for the surgeon to help plan safer incisions and better reconstructive flap procedures. It also gives information that may help explain the etiology and treatment of head and neck arteriovenous vascular malformations.

Arteries↗

PubMed2000

Surgical anatomy of the ligamentous attachments in the temple and periorbital regions.

This study documents the anatomy of the deep attachments of the superficial fasciae within the temporal and periorbital regions. A highly organized and consistent three-dimensional connective tissue framework supports the overlying skin and soft tissues in these areas. The regional nerves and vessels display constant and predictable relationships with both the fascial planes and their ligamentous attachments. Knowledge of these relationships allows the surgeon to use the tissue planes and soft-tissue ligaments as intraoperative landmarks for the vital neurovascular structures. This results in improved efficiency and safety for aesthetic procedures in these regions.

Aged↗

PubMed1999

The use of titanium mandibular reconstruction plates in patients with oral cancer.

A series of 21 patients, who were selected for primary mandibular stabilisation with titanium plates following excision of advanced malignant tumours, is reported. Success was defined as a plate that did not have to be removed due to fracture, exposure or infection. The overall success rate was 71%, with follow-up ranging from 7-53 months. The majority of plate losses were experienced when either anterior or large lateral defects which included the condyle were bridged and when patients were subjected to either pre- or postoperative radiotherapy.

Aged↗

PubMed1999

Free vascularized nerve transfer in the upper extremity.

Free vascularized nerve transfer using microsurgical techniques for upper limb reconstruction should be considered as an alternative to conventional nonvascularized cable nerve grafts when the recipient bed is heavily scarred, as occurs in Volkmann's ischemia, when the nerve gap is exceptionally long, or when the free transfer of thick nerves is contemplated. Possible donor sites for free arteriovenous nerve transplants or arterialized neurovenous systems are presented and illustrated in four patients with follow-up in excess of 20 years. In each case the rate of axon immigration across the vascularized nerve-bridge and beyond to the hand was in excess of 1.5 mm per day.

Adult↗

PubMed1999

The angular branch of the thoracodorsal artery and its blood supply to the inferior angle of the scapula: an anatomical study.

An anatomical study of the thoracodorsal arterial system was performed; it focused on the angular branch. The aim of the study was to document the anatomical variations of this pedicle and to delineate the area of supply to the inferior angle of the scapula with a view to free bone transfer. A total of 81 cadaver dissections were performed; they revealed the constant presence of the thoracodorsal artery and four vascular patterns of origin of the angular branch. Selective India ink perfusion studies performed on 11 sides in six fresh cadavers demonstrated a reliable supply to the inferior angle of the scapula to the extent of 6 cm of the vertebral margin and 3 cm of the lateral margin of the scapula. Histologic analysis of sections of this region of the scapula confirmed the presence of ink within the periosteal, cortical, and medullary vascular channels, implying the viability of this area of bone if transferred based on the angular branch.

Cadaver↗

PubMed1998

Angiosomes of the leg: anatomic study and clinical implications.

In 1987, Taylor and Palmer introduced the angiosome concept. This anatomical study defined the three-dimensional vascular territories supplied by source arteries and veins to each tissue layer between the skin and the bone. This report, however, was an overview investigation and did not study each region of the body in fine detail. In 1996, Inoue and Taylor studied the angiosomes of the forearm in much greater detail. They showed, among other findings, that the zone between the angiosomes, formed by reduced caliber (choke) vessels or similar caliber (true) anastomotic arteries, occurred usually within tissues, especially the muscles, not between them. This study focuses on the same region in the lower limb to draw a comparison and to fill certain voids in our knowledge--the leg. Twelve lower limbs from fresh cadavers were investigated over a 2-year period after perfusing each with a mixture containing radio-opaque lead oxide. The anatomy of the arterial supply to the skin, the muscles, and the periosteum of the bones of the leg was examined. The contribution to each tissue was defined by dissection, by metal clip tagging of vessels, by radiography, and by mapping the branches with colored pins, coded to match the respective source arteries. A subtraction technique was used to study the muscles whereby the bones of the limb were replaced with radiolucent balloons to obtain an unobscured picture of the vasculature of the leg. The muscles were then segregated one by one from the muscle mass and x-rayed again. Next, cross-section studies were made in two legs to complete the three-dimensional picture, tracing the branches from the source arteries to each layer. Finally, the contribution to each tissue from the popliteal, sural, anterior tibial, posterior tibial, and peroneal vessels were color coded to match these source arteries, thus defining the angiosomes of the leg. Results, as in the forearm, showed that in most cases the connections between adjacent angiosomes occurred within tissues, not between them. The skin, the bones, and most muscles received branches from two or more angiosomes, thus revealing one of the important anastomotic pathways through which the circulation is reconstituted when a source artery is interrupted by disease or trauma. Notably, however, the muscles of the anterior compartment of the leg were supplied from one angiosome. This finding, coupled with the anatomy of the rigid fascial compartments of the leg, helps explain the variable clinical pictures and syndromes seen in cases in which the circulation is compromised or interrupted. Finally, this anatomical study adds further information to help design or redesign flaps in the leg for local or free transfer. Similarly, the information reveals the pathways through which the supply to the remaining tissues is reconstituted when one of the source arteries is harvested with a free flap, especially when multiple tissues are included in the transplant.

Arteries↗

PubMed1996

The angiosomes of the forearm: anatomic study and clinical implications.

The angiosome concept was introduced in 1987 by Taylor and Palmer. Their anatomic study correlated the blood supply to the skin from the named segmental or distributing "source" arteries with their supply to the underlying muscles, tendons, nerves, and bones. Although this investigation encompassed the body, there were areas where the supply to individual tissues was not examined in detail. The present study, therefore, examines one of these regions where certain voids in our knowledge still exist--the forearm. Ten upper limbs from fresh cadavers were studied over an 18-month period after perfusing each with a radiopaque lead oxide mixture. The arterial supply to the skin and the bones of the forearm, together with that of a total of 200 muscles, was examined. The contribution to each was defined by dissection, by metal clip tagging of vessels, by radiography, and by mapping the branches with colored pins coded to match the respective source arteries. In the case of the muscles, a subtraction technique was used whereby the bones of the extremity were replaced with radiolucent balloons to obtain an unobscured picture of the forearm vasculature. Then the muscles were removed one by one from the muscle mass and x-rayed again. In this way, the angiosomes in the forearm, provided by the brachial, radial, ulnar, and interosseous arteries, were defined. Similarly, the contribution from each angiosome to the skin, to each muscle, and to the radius and the ulna was identified and the territories were color-coded to match these source arteries. Results showed that in most cases the connections between adjacent angiosomes occurred within tissues, not between them. The skin, the bones, and most muscles received branches from the source arteries of at least two angiosomes, thus revealing one of the important anastomotic pathways by which the circulation is reconstituted in those cases where a source artery is interrupted by disease or trauma. Several muscles, however, were supplied within one angiosome. This helps explain the variable clinical pictures seen in cases where the circulation is interrupted, such as that which occurs in a Volkmann's ischemic contracture. Finally, this anatomic study provides further information to help design various flaps from the forearm for local or free transfer. In the case of muscles, the supply to most from multiple angiosomes allows for refinements whereby a portion only of a muscle can be used. Similarly, this anatomic information reveals the pathway by which the supply to remaining muscle groups is reconstituted when one of the source arteries is harvested with a skin flap, a muscle, or part thereof.

Brachial Artery↗

PubMed1995

The time sequence of the delay phenomenon: when is a surgical delay effective? An experimental study.

We have shown previously that when a flap is delayed, the maximal anatomic effect on the arterial side of the circulation is focused at the level of the reduced-caliber choke vessels that link adjacent vascular territories. These anastomotic vessels were noted to increase in size to the dimension of true anastomoses. However, we did not define when this occurred. The present experiment therefore was designed to elucidate the chronologic sequence of events that occur in the "choke" vessels using a rabbit flank skin flap as the experimental model. A long two-territory osteocutaneous flank flap was designed on one side of each rabbit (n = 30), with the opposite unoperated side serving as a control. The flap was elevated and sutured back in place. At various times postoperatively, namely, 1 (n = 2), 2 (n = 2), 3 (n = 2), 4 (n = 2), 6 (n = 2), 8 (n = 2), 12 (n = 2), 24 (n = 2), 48 (n = 2), and 72 (n = 2) hours and 7 days (n = 10), the animals were sacrificed, and total-body arteriograms were obtained using a lead oxide mixture. The density and size of the choke arteries between the territories in the flap and their counterparts on the control side were assessed by histologic analysis (n = 3). We observed a sequential dilation of choke vessels during the delay period. In particular, we found that the vessels increased rapidly in size between the 48- and 72-hour studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

TRAM flap anatomy correlated with a 10-year clinical experience with 556 patients.

This study examines the vascular anatomy of the TRAM flap and evaluates risk factors associated with complications among 556 women who had TRAM flap breast reconstruction. Fifty-nine patients (10.6 percent) developed fat necrosis involving 10 percent or more of their breast. Risk factors associated with fat necrosis were a history of chest-wall irradiation (p = 0.001), significant abdominal scar (p < 0.01), and obesity (p < 0.02). Among unipedicle reconstructions, patients with multiple risk factors had three times the incidence of fat necrosis (24.7 versus 8.3 percent) compared with patients with one or no risk factors (p < 0.002). Patients with multiple risk factors who had bipedicled TRAM flap reconstruction had no associated increased incidence of fat necrosis (p > 0.18). Forty-nine patients (8.8 percent) developed abdominal hernias. Risk factors associated with hernia formation included smoking at the time of surgery (p = 0.00001) and abdominal-wall repair with interposed mesh (p < 0.00001). The overall complication rate for this series was 23.7 percent (132 of 556). Risk factors associated with any complication included smoking (p < 0.002), history of chest-wall irradiation (p < 0.002), significant abdominal scar (p < 0.005), and obesity (p < 0.02). Patient selection is a fundamental determinant of successful TRAM flap breast reconstruction. Among patients with multiple risk factors, the risk of tissue loss in the reconstructed breast may be diminished by use of a bipedicled TRAM flap.

Breast Neoplasms↗

PubMed1994

The neurovascular territories of the skin and muscles: anatomic study and clinical implications.

In 1987, the results of a series of total-body investigations of the arterial system of the skin and underlying deep tissues were published. This resulted in the angiosome concept. In 1990, a similar series of studies of the venous network was published. In both investigations, it was noted that "vessels hitchhike with nerves." This anatomic study analyzes these neurovascular relationships in the skin and in the underlying muscles. Seven fresh human cadavers and nine animals were studied over a 2-year period. The entire integument of each and a total of 538 human and 72 animal muscles were removed and analyzed. Either the arterial or the venous system was injected with a radiopaque lead oxide mixture, and the dissected nerves were labeled with fine wires, being segregated later by a subtraction radiography technique. The results of these investigations are presented, with special emphasis placed on the design of long axial skin flaps placed along neurovascular systems and their relationship with the current design of skin flaps. The muscles are classified according to their extrinsic and intrinsic neurovascular supplies, and suggestions are made as to how they may or may not be subdivided into functional units for local and distant transfer. The cutaneous nerves, as well as the motor nerves of the muscles, were invariably accompanied by a longitudinal system of arteries and veins that often was the dominant supply to the region. Whether the nerves appeared together with the vessels, whether the nerves crossed them at an angle, or whether they approached the vessels from opposite directions, in each case the main trunk of the vessel or some of its branches soon "peeled off" to course parallel to the nerve. This information provides the basis for the design of long skin flaps placed along neurovascular systems. Indeed, it reveals that many of the current "axial" or "fasciocutaneous" skin flaps used in clinical practice are in fact neurovascular flaps. The muscles are classified into four types according to their extrinsic and intrinsic neurovascular supplies. Type I muscles are supplied by a single unbranched nerve. In type II muscles, the nerve branches before entering the muscle. Type III muscles receive multiple motor nerves from the same nerve trunk, and type IV muscles are supplied from multiple nerve trunks. Suggestions are made as to how muscles of each type may or may not be subdivided into functional neurovascular units for local and distant transfer.(ABSTRACT TRUNCATED AT 400 WORDS)

Anatomy, Comparative↗

PubMed1993

The deep venous system and reverse flow flaps.

The deep venous system of the upper and lower extremities was injected with a lead oxide mixture in 2 fresh human cadavers, dissected, radiographed and the sites of the venous valves located. These studies confirmed that the macrovenous connections between the venae comitantes of the distributing arteries were insufficient in number to bypass the venous valves in conventional, distally based reverse flow flaps (e.g. radial, ulnar, peroneal) but revealed an alternative microvenous interconnecting pathway which surrounds the artery as the venae arteriosa. This pathway was investigated in a series of distally based reverse flow saphenous flaps in dogs, comparing flaps where the microvenous connections were left intact (non-skeletonised) with those where these vessels were disconnected with the operating microscope (skeletonised). All non-skeletonised flaps survived subtotally or totally whereas total necrosis was observed in 70% of the skeletonised flaps. Finally a series of haemodynamic studies was performed to test valve competency including extrinsic pressure on the valves. It is concluded that the macrovenous and microvenous pathways, coupled with the variable anatomy of the venous valves, are major factors in determining the survival of reverse flow flaps.

Animals↗

PubMed1993

Predicting the survival of experimental skin flaps with a knowledge of the vascular architecture.

Experimental skin flaps have been utilized by researchers for almost a century to investigate many of the perplexing questions in plastic and reconstructive surgery, yet the underlying vascular anatomy of these flaps is addressed infrequently. The purpose of this study was to predict the survival of experimental skin flaps prior to their elevation in guinea pigs and rabbits, planned on a knowledge of the underlying vascular anatomy. On the basis of our previous anatomic studies, 17 guinea pigs and 15 rabbits were used in separate experiments. In experiment 1, two parallel flank flaps of identical dimensions were compared on one side of each guinea pig. The dorsal flap encompassed the vascular territories of multiple perforators, while the ventral flap embraced two perforators (two-territory flap). Viability was assessed on days 3 and 7 by inspection and fluorescein dye injection. All ventral flaps survived to a greater extent than the dorsal flaps. Whole-body fresh cadaver lead oxide injections were performed to provide cutaneous angiograms. It was found in each flap that the area of skin viability corresponded to the capture of one to two adjacent vascular territories on the artery at its base. In the second experiment, a multiple-territory osteocutaneous flap was designed on one side of the torso of the rabbit using the Doppler probe. It was based on the thoracodorsal artery and embraced the skin and a 1 x 2 cm segment of iliac crest bone in the adjacent deep circumflex iliac artery angiosome. Using the same criteria as in experiment 1, we found that one to two adjacent viable skin territories were captured on the thoracodorsal artery. In addition, viability of the iliac bone was confirmed in every case by angiography, fluorochrome labeling, and india ink injection studies indicating the capture of deep structures of the deep circumflex iliac artery angiosome. This study reinforces the angiosome concept and indicates that one adjacent vascular territory may be captured reliably in experimental guinea pig and rabbit skin flaps. In addition, we have described a reliable osteocutaneous flap model in the rabbit.

Animals↗

PubMed1992

Scalp replantation by arterialised venous network flow-through.

A successful clinical case of scalp replantation is presented where a suitable artery could not be identified in the amputated part. Reperfusion of the flap was achieved by an arteriovenous inflow anastomosis and a conventional venous anastomosis for drainage. The aesthetic and physiological success of this case suggests that arteriovenous scalp replantation is a potential avenue for treatment where arterio-arterial repair is not possible. The possible explanation for the success in this patient is the paucity of valves that exist in the venous network of the scalp and forehead, noted in our previous anatomical studies. Knowledge of the replanted tissue venous architecture provides an anatomical basis to understand the potential limitations of arteriovenous replantation.

Adult↗

PubMed1992

The angiosomes of the mammals and other vertebrates.

This is a comparative study of the vasculature of the integument and underlying deep tissues of a range of mammals and other vertebrates. The investigation was conducted in the pig, monkey, dog, cat, possum, guinea pig, rat, rabbit, duck, and toad. The results from each are compared not only to each other, but also to previously performed human studies. The arterial network of the fresh animal cadaver was injected with a mixture of lead oxide and gelatin. The vascular anatomy of the skin, deep tissues, and individual muscles was defined by dissection, cutaneous perforator counts, photography, and radiography. A similar pilot study of the venous framework was performed in the pig, dog, and rabbit that included maps of the sites and orientations of the valves. The vasculature of the integument and deep tissues was correlated, and we found that we were able to define angiosomes (composite blocks of tissue supplied by the same source vessel) in each animal. Results revealed a marked dissimilarity of the overlying cutaneous vessels in many cases, yet a striking resemblance of the vascular architecture of the deep tissues. The size and density of the cutaneous perforators bore a close relation to the degree of the skin mobility, being large and sparse where the skin was mobile and smaller and more densely grouped where the integument was tethered or fixed. The cutaneous vasculature of the human resembled that of the monkey closely, was similar to that of the dog, cat, and possum, and was dissimilar to that of the pig, rat, guinea pig, and rabbit. Studies of the amphibian and bird bore many resemblances to those of the mammals. They provided basic concepts regarding modification of the animals' vascular anatomy in response to the functional demands of the species. In each animal, the arteries formed an unbroken network throughout the body. This consisted of anatomic territories linked by anastomotic vessels that were usually of reduced caliber. The pattern of the venous system was almost identical. Valved venous territories were linked by avalvular (oscillating) veins. The common denominator in the vascular system is the capillary bed. Conceptually, the anatomic arrangement of the arteries and veins, reproduced in each species, appears to be a sophisticated mechanism to allow equilibration of flow and pressure arriving at and departing from the capillary bed. The angiosome concept is reinforced by the animal studies. Although this investigation is essentially a detailed pilot study, it embraces many animals commonly used for experimentation and provides a reference atlas of their vasculature.(ABSTRACT TRUNCATED AT 400 WORDS)

Anatomy, Comparative↗

PubMed1992

An anatomic review of the delay phenomenon: I. Experimental studies.

A number of experiments were conducted to study the anatomic changes in a flap following a surgical delay using the Doppler probe to add precision to the technique. After scanning the integument of a series of anesthetized animals with the probe, each was sacrificed; a total-body arterial injection was performed with a lead oxide mixture, the integument and deep tissues were radiographed separately, and the results were correlated and compared with our previous human studies. The dog was selected from the range of animals examined, and the arterial networks of a number of skin and muscle flaps were studied with and without a surgical delay. The study included the use of a tissue expander. Results revealed that an adjacent cutaneous perforator could be captured with safety on the artery at the base of an undelayed flap; that the survival length of that flap was related to the distance between perforators; that the necrosis line of the flap usually appeared in the zone of choke vessels connecting adjacent territories; that a surgical delay results in a dilatation of existing vessels with maximal effect in the zone of choke arteries; that the most effective delay was obtained by elevating the flap in stages from the base, leaving detachment of the tip until last; that tissue expansion is a form of surgical delay, with particular emphasis on vessel hypertrophy; and that similar changes occur when a muscle is delayed. The clinical applications of this investigation are presented in Part II of this anatomic review of the delay phenomenon.

Animals↗

PubMed1992

An anatomic review of the delay phenomenon: II. Clinical applications.

This paper applies the anatomic concepts and data obtained from our animal experimental studies of the delay phenomenon to a series of clinical cases. Similar clinical results were obtained to those seen in Part I of our study when skin flaps were raised with and without a delay, when a tissue expander was used, and when the delay technique was extended to musculocutaneous flaps. In each instance, the cutaneous perforators were identified with the Doppler probe to facilitate the delay of specific vessels rather than dividing those at random. Intraoperative arteriograms and venograms reveal that the choke arteries dilate and the anatomically unfavorable valved vein segments become regurgitant. The end result is the observation that at least one additional anatomic vascular territory can be added to the length of a flap with safety following a surgical delay.

Adult↗

PubMed1990

The Doppler probe for planning flaps: anatomical study and clinical applications.

The Doppler probe was used to identify the dominant cutaneous perforating arteries in a series of 10 patients. The results were compared with our previous total body fresh cadaver anatomical studies and a close correlation was found. The instrument was used in a series of patients to plan the base, the axis and the dimensions of skin flaps for local, distant and free transfer. A dominant perforator was located at the base of the flap, the surrounding skin was scanned to identify the next dominant perforator in each direction and the appropriate axis was chosen by drawing a line between two nominated perforators. Often the flap was based distally or its axis departed from the main course of the supplying vessel. The technique proved to be simple and reliable and in many cases flaps of unusual dimensions and directions were transferred successfully. The instrument provides a useful link between the anatomical dissecting room and the operating theatre.

Adolescent↗

PubMed1990

The venous drainage of nerves; anatomical study and clinical implications.

The venous drainage of the peripheral nerves was studied in the upper and lower limbs of two human fresh cadaver subjects after total body perfusion with a radio-opaque lead oxide mixture. Four patterns of extraneural drainage were identified in which the venae nervosa drained: directly to the venae comitantes of the neurovascular bundle; indirectly via nearby veins, derived usually from muscles; to the periarterial venous plexus; or, in the case of the cutaneous nerves, to the perivenous plexus. The various patterns of the drainage along the length of the radial, median, ulnar, sciatic, anterior and posterior tibial nerves were identified. A rich longitudinal plexus of veins exists on and within the nerve which appears to be mainly free of valves. The large venae nervosa usually contained valves, whereas the tiny veins draining the nerves were valveless or exhibited a sentinel valve at their entry point into a larger venous channel. The clinical implications of these results are discussed in relation to the mobilisation of nerves, the use of island nerve flaps, possible donor sites for free arteriolised neurovenous flaps and the compressive nerve syndromes.

Brachial Plexus↗