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Biomedical subjects

G I Taylor

Publications and source records attributed to G I Taylor.

At least 19 recordsLinked to original sources
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↗
PubMed1990

The venous territories (venosomes) of the human body: experimental study and clinical implications.

The venous architecture of the integument and the underlying deep tissues was studied in six total-body human fresh cadavers and a series of isolated regional studies of the limbs and torso. A radiopaque lead oxide mixture was injected, and the integument and deep tissues were dissected and radiographed. The sites of the venous perforators were plotted and traced to their underlying parent veins that accompany the source (segmental) arteries. A series of cross-sectional studies were made in one subject to illustrate the course of the perforators between the integument and the deep tissues. The veins were dissected under magnification to identify the site and orientation of the valves. Results revealed a large number of valveless (oscillating) veins within the integument and deep tissues that link adjacent valved venous territories and allow equilibration of flow and pressure throughout the tissue. Where choke arteries define the arterial territories, they are matched by boundaries of oscillating veins in the venous studies. The venous architecture is a continuous network of arcades that follow the connective-tissue framework of the body. The veins converge from mobile to fixed areas, and they "hitchhike" with nerves. The venous drainage mirrors the arterial supply in the deep tissues and in most areas of the integument in the head, neck, and torso. In the limbs, the stellate pattern of the venous perforators is modified by longitudinal channels in the subdermal network. However, when an island flap is raised, these longitudinal channels are disconnected, and once again the arterial and venous patterns match. Our venous studies add strength to the angiosome concept. Where source arteries supply a composite block of tissue, we have demonstrated radiologically and by microdissection that the branches of these arteries are accompanied by veins that drain in the opposite direction and return to the same locus. Hence each angiosome consists of matching arteriosomes and venosomes. The clinical implications of these results are discussed with particular reference to the design of flaps, the delay phenomenon, venous free flaps, the pathogenesis of flap necrosis, the "muscle pump," varicose veins, and venous ulceration.

Aged↗
PubMed1989

The "chemical leech": intra-replant subcutaneous heparin as an alternative to venous anastomosis. Report of three cases.

Three successful cases of distal finger replantation are described where suitable veins were unavailable for anastomosis after arterial flow had been re-established. To prevent infarction, calcium heparin was injected subcutaneously into the replants at intervals over 9 days. This allowed the venous blood to escape into the dressings while an adequate microvenous circulation was re-established, thus simulating the effect of a leech. Complete survival of all three distal replantations was observed. No attempted case has been unsuccessful. The procedure is simple and can be administered by the nursing staff. It avoids some of the problems associated with the use of medicinal leeches and systemic heparin. Applications of this technique in other areas of replantation and flap surgery are suggested.

Adult↗
PubMed1988

The anterior tibial vessels and their role in epiphyseal and diaphyseal transfer of the fibula: experimental study and clinical applications.

The blood supply to the fibula from the anterior tibial and peroneal arteries was investigated in 66 fresh cadaver limbs by India ink injection and radiographic studies. These studies revealed a reliable blood supply to the proximal epiphysis and the proximal two-thirds of the diaphysis of the fibula from the anterior tibial artery. Although the peroneal artery provided the dominant supply to the shaft of the bone, its contribution to the head of the fibula was scanty. The cutaneous supply of each vessel was defined and correlated with the territories of the other vessels supplying the leg. The vascular anatomy of the leg was examined in 100 clinical angiograms, revealing 21 limbs with anomalies. This reinforces the case for preoperative angiogram studies where transfer of the fibula is contemplated. The technique of harvesting the proximal growth plate and the shaft of the fibula on the anterior tibial vessels alone is described and illustrated with two successful clinical cases, each followed for 4 years. The growth rate of the transferred epiphysis averaged 1 cm per year.

Blood Vessels↗
PubMed1988

The venous territories of muscles: anatomical study and clinical implications.

The venous architecture of the muscles of the body was studied in 425 specimens obtained from four fresh cadavers after total body injection with a radio-opaque lead oxide mixture. In 40 muscles the site and orientation of the valves was identified with the operating microscope. The venous network of each muscle was compared with similar arterial studies. The venous territories in each muscle matched the arterial territories. Where arterial territories were linked with choke arteries the venous territories were linked by veins devoid of valves which allowed bidirectional flow--the "oscillating veins". Elsewhere the valves of adjacent territories were directed away from each other and towards their respective pedicles. These anatomical observations reinforce our angiosome concept. The muscles were classified into Type A, B and C where there were one, two or more territories respectively. When a skin paddle is designed distally on a Type B or C muscle its venous return at first must negotiate the anatomical obstruction of the valves of the distal muscle territory before reaching the safety of the oscillating veins and the venous territory of the drainage pedicle. Finally, afferent veins were noted entering many muscles from the superficial and deep tissues. This highlights the importance of the muscles in aiding venous return by their muscle pump action.

Arteries↗
PubMed1988

The vascular anatomy of rectus abdominis musculocutaneous flaps based on the deep superior epigastric system.

Radiographic studies of the deep superior epigastric artery (DSEA) and its connections within the soft tissues of the abdominal wall were performed in 64 fresh cadavers. The patterns of anastomosis between the deep superior epigastric artery and the deep inferior epigastric artery (DIEA) were noted. Type I (29 percent) revealed a single deep superior epigastric artery and deep inferior epigastric artery, type II (57 percent) revealed a double-branched system of each vessel, and type III (14 percent) revealed a system of three or more major branches. In each case, the two systems were united by choke vessels in the segment of muscle above the umbilicus. The supply to the various transverse and vertical skin flaps from the deep superior epigastric artery was defined as a series of captured anatomic territories bounded by choke vessels. The upper transverse and vertical flaps had the best supply, and the TRAM flap had the most tenuous supply. Midline crossover occurs predominantly in the subdermal plexus and on the surface of the rectus sheath. Modifications of the design of the TRAM flap, the case for a delay procedure, the wisdom of including a strip of anterior rectus sheath, and the risks of splitting the muscle with respect to its nerve supply and vascular patterns are discussed on an anatomic basis.

Abdominal Muscles↗
PubMed1987

The vascular territories (angiosomes) of the body: experimental study and clinical applications.

The blood supply to the skin and underlying tissues was investigated by ink injection studies, dissection, perforator mapping and radiographic analysis of fresh cadavers and isolated limbs. The results were correlated with previous regional studies done in this department. The blood supply is shown to be a continuous three-dimensional network of vessels not only in the skin but in all tissue layers. The anatomical territory of a source artery in the skin and deep tissues was found to correspond in most cases, giving rise to the angiosome concept. Arteries follow closely the connective tissue framework of the body. The primary supply to the skin is by direct cutaneous arteries which vary in calibre, length and density in different regions. This primary supply is reinforced by numerous small indirect vessels, which are "spent" terminal branches of arteries supplying the deep tissues. An average of 374 major perforators was plotted in each subject, revealing that there are still many more potential skin flaps. Our arterial roadmap of the body provides the basis for the logical planning of incisions and flaps. The angiosomes defined the tissues available for composite transfer.

Arteries↗
PubMed1987

A new radio-opaque injection technique for tissue preservation.

This study has investigated the action of two commonly available preservatives, chlorbutol and chlorocresol, on fresh cadaver tissue. If the arterial system of the subject is perfused first with either preservative then the progression of tissue necrosis can be delayed for up to 1 month. The preservative can be combined with the lead oxide-gelatin mixture described by Rees and Taylor without compromising the results of radiographic studies. Both chlorocresol and chlorbutol have the advantage over formalin of retaining the normal colour and texture of the tissues. A regimen is suggested which has all of the advantages of the mixture originally described by Salmon, but is much simpler and cheaper to produce. It has proved successful when used in whole cadavers but the visceral contents must be removed at an early stage.

Chlorobutanol↗
PubMed1986

The clavicular head of pectoralis major musculocutaneous free flap.

A new free flap is described based on the deltoid vessels of the acromiothoracic axis. The flap is comprised of the clavicular head of pectoralis major muscle with overlying skin. It is also possible to harvest vascularised clavicular bone with the flap. The vascular anatomy is reviewed and the technique of raising the flap described. Its clinical application is illustrated with five cases. Four of these were intra-oral reconstructions and the fifth a composite osteo-musculocutaneous flap to a lower limb following trauma.

Adult↗
PubMed1986

The vascular territories of the anterior chest wall.

A series of 31 fresh cadaver injection, dissection and radiographic studies were undertaken to define the vascular architecture of the anterior chest wall and to correlate the findings of previous writers in this area. The findings confirmed that the dominant supply to this region is from the internal thoracic artery which interconnects in all layers with the posterior intercostals, the lateral thoracic, the acromio-thoracic and the transverse cervical arteries. The dominant cutaneous perforators of these vessels are concentrated around the perimeter of the pectoralis major muscle, the costal margin and over the interdigitations of the serratus anterior muscle in the mid-axillary line. The clinical significance of these findings is discussed with particular reference to the design of various breast reduction procedures and the planning of flaps in this area. Of special note is the observation that the concentration of large perforators which exists along the inframammary crease arises from the anterior intercostal vessels in the fifth and sixth intercostal spaces.

Humans↗
PubMed1986

The anatomy of the thoracodorsal artery within the latissimus dorsi muscle.

This paper reports the findings of an anatomical study of the primary and secondary muscular branches of the thoracodorsal artery within the latissimus dorsi muscle. Twenty latissimus dorsi muscles were studied, harvested from 13 fresh cadavers and the findings support the hypothesis that it is possible to thin safely a latissimus dorsi muscle flap at the time of flap transfer.

Arteries↗
PubMed1986

A simplified lead oxide cadaver injection technique.

A simple, inexpensive injectable substance is reported for analysis of the arterial circulation in fresh human or animal cadavers. The technique is a modification of that reported by Salmon in 1936 and utilizes lead oxide and gelatin. This combination is highly radiopaque; it perfuses the small radicles of the vascular tree and sets to a firm rubbery consistency to fascilitate dissection.

Angiography↗