- Email: [email protected]
Continuous sutures for end-to-side micro-arterial anastomoses
424
BRITISH JOURNAL OF PLASTIC SURGERY
Microsurgical
approach for experimental
ischaemia
T. SHIGENO and G. M. TEASDALE Department
of Neurosurgery,
University of Glasgow
Sudden occlusion of the middle cerebral artery (MCA) is one of the common strokes in humans which causes ischaemic brain damage and neurological deficit. Although a number of experimental approaches to produce MCA occlusion were performed using larger animals such as monkeys and cats, MCA occlusion in rats which was originally devised in Glasgow (Tamura et al., 1981) provided a useful means to investigate the pathophysiology of focal cerebral ischaemia particularly when combined with the autoradiographic techniques because of the reduced requirement of expensive radioisotopes in small animals. Through a subtemporal craniectomy under the operative microscope, the trunk of MCA was exposed. There was an important tiny arterial branch called lenticulostriate artery which arose from the very proximal part of the MCA and supplied circulation to the caudate nucleus. The circulatory and neuropathological consequences were quite different whether or not this artery was involved. The “proximal” occlusion which involved both the MCA and the lenticulostriate artery produced ischaemia and ischaemic brain damage in both cortex and the caudate nucleus, whereas the “distal” occlusion without occluding the lenticulostriate artery produced only cortical damage. Since the sites of occlusion for both types were so close, a careful microsurgical technique was required. The neuropathological consequence was found much more consistent and severe in proximal occlusion. Several autoradiographic investigations were carried out to investigate cerebral blood flow using
Continuous
sutures for end-to-side
(14C)-iodoantipyrine, cerebral glucose metabolism using (14C)-2-deoxyglucose, blood-brain barrier permeability using (14C)-aminoisobutyric acid and protein synthesis using (14C)-leucine. Heterogeneous alterations were found in each of the autoradiographic indices but these could be well correlated with a combined use of enzyme histochemistry for glycogen phosphorylase which could delineate the lesion. A greater interest was focused on the areas outside .the irreversibly damaged ischaemic core which were not yet dead and potentially salvageable. The autoradiographic investigations showed that this was an area with a metabolic activation through an enhanced anaerobic glycolysis. A model of reversible ischaemia was also established by utilizing a snare ligature in the trunk of the MCA. It was found that a short period of ischaemia for 30 minutes caused prolonged derangement in local cerebral circulation even after initial full restoration of cerebral perfusion. In conclusion, a small animal model of focal cerebral ischaemia can provide a sound basis for the study of ischaemic pathophysiology in the brain when a careful microsurgical technique is used.
Reference Tamura, A, Graham, D. I. McCulloch J, and Teasdale G. M. (1981). Focal cerebral ischaemia in the rat: 1. Description of technique and early neuropathological consequences following middle cerebral artery occlusion. Journal of Cerebral Blood Flo w and Metabolism, 1, 53.
micro-arterial
anastomoses
M. J. TIMMONS Surgical Laboratories,
Royal Postgraduate Medical School, London
Continuous suture techniques are routine in peripheral vascular surgery and they have also been used in experimental and clinical microsurgery.
A continuous suture technique for end-to-side anastomoses has been developed in a rat carotidto-carotid model. Reliability of the technique was
BRITISH MICROSURGICAL
425
SOCIETY MEETING 1983
tested in a series of ten consecutive animals. After two days (one animal) or three weeks (nine animals) all anastomoses were patent at a second Histology (Dr M. H. Bennett, operation. Northwood) confirmed patency and showed no anastomotic stenosis or thrombosis. Continuous sutures would seem to be especially suitable when there is limited access to the posterior wall of an anastomosis or when anastomosing the larger vessels now employed in free flap and other reconstructive surgery. Two points raised in the discussion should be noted. First (Prof. R. D. Acland, Louisville), one
should try to avoid difficulties such as anastomoses with limited access. Second (Mr D. R. Bird, Edinburgh), at least some interrupted sutures are needed if dilatation of the anastomosis is for with dialysis example anticipated, arteriovenous fistulas, extra-cranial intra-cranial revascularisation and paediatric microsurgery.
Reference Timmons, M. J. (1984). Continuous sutures for micro-arterial end-to-side anastomoses. Plastic and Reconstructive Surgery (In press).
The mechanisms of flap oedema following control with salbutamol
free transfer in man and its
A. G. BATCHELOR,
G. S. BASRAN,
J. G. HARDY, D. PEARSON and L. SULLY
Departments
Surgery,
and Medical
of Plastic
Medicine
The ischaemia and manipulation of free flap transfer engenders acute inflammation. The final common path of this mechanism is a cell-rich exudative oedema occurring from the microcirculation. All free flaps swell to some degree after transfer.
Materials and methods This phenomenon and its modification with the drug salbutamol has been studied in human subjects using a double radioisotope technique. Technetium 99 m was used to label the red cells, and Indium 113 m was used to label the plasma transferrin as an indicator of plasma protein. Observations were made of a free flap after it had been raised, and after it had been transferred. The post-transfer measurements were in two phases,
Physics,
Nottingham
Group of Hospitals
firstly before, and secondly after, the administration of 250 micrograms of salbutamol intravenously. The Technetium counts were an index of the red cell mass within the flap and the Indium counts an index of the plasma protein within the flap. Any disproportionate increase of Indium over Technetium indicated the formation of exudative oedema. Results These showed that flap oedema occurs as soon as a flap is raised, that the rate of formation increases after the period of ischaemia necessary for free transfer and that intravenous salbutamol appears to reduce and in some cases abolish, the formation of oedema following its administration. Salbutamol did not affect flap blood flow.
BRITISH JOURNAL OF PLASTIC SURGERY
Microsurgical
approach for experimental
ischaemia
T. SHIGENO and G. M. TEASDALE Department
of Neurosurgery,
University of Glasgow
Sudden occlusion of the middle cerebral artery (MCA) is one of the common strokes in humans which causes ischaemic brain damage and neurological deficit. Although a number of experimental approaches to produce MCA occlusion were performed using larger animals such as monkeys and cats, MCA occlusion in rats which was originally devised in Glasgow (Tamura et al., 1981) provided a useful means to investigate the pathophysiology of focal cerebral ischaemia particularly when combined with the autoradiographic techniques because of the reduced requirement of expensive radioisotopes in small animals. Through a subtemporal craniectomy under the operative microscope, the trunk of MCA was exposed. There was an important tiny arterial branch called lenticulostriate artery which arose from the very proximal part of the MCA and supplied circulation to the caudate nucleus. The circulatory and neuropathological consequences were quite different whether or not this artery was involved. The “proximal” occlusion which involved both the MCA and the lenticulostriate artery produced ischaemia and ischaemic brain damage in both cortex and the caudate nucleus, whereas the “distal” occlusion without occluding the lenticulostriate artery produced only cortical damage. Since the sites of occlusion for both types were so close, a careful microsurgical technique was required. The neuropathological consequence was found much more consistent and severe in proximal occlusion. Several autoradiographic investigations were carried out to investigate cerebral blood flow using
Continuous
sutures for end-to-side
(14C)-iodoantipyrine, cerebral glucose metabolism using (14C)-2-deoxyglucose, blood-brain barrier permeability using (14C)-aminoisobutyric acid and protein synthesis using (14C)-leucine. Heterogeneous alterations were found in each of the autoradiographic indices but these could be well correlated with a combined use of enzyme histochemistry for glycogen phosphorylase which could delineate the lesion. A greater interest was focused on the areas outside .the irreversibly damaged ischaemic core which were not yet dead and potentially salvageable. The autoradiographic investigations showed that this was an area with a metabolic activation through an enhanced anaerobic glycolysis. A model of reversible ischaemia was also established by utilizing a snare ligature in the trunk of the MCA. It was found that a short period of ischaemia for 30 minutes caused prolonged derangement in local cerebral circulation even after initial full restoration of cerebral perfusion. In conclusion, a small animal model of focal cerebral ischaemia can provide a sound basis for the study of ischaemic pathophysiology in the brain when a careful microsurgical technique is used.
Reference Tamura, A, Graham, D. I. McCulloch J, and Teasdale G. M. (1981). Focal cerebral ischaemia in the rat: 1. Description of technique and early neuropathological consequences following middle cerebral artery occlusion. Journal of Cerebral Blood Flo w and Metabolism, 1, 53.
micro-arterial
anastomoses
M. J. TIMMONS Surgical Laboratories,
Royal Postgraduate Medical School, London
Continuous suture techniques are routine in peripheral vascular surgery and they have also been used in experimental and clinical microsurgery.
A continuous suture technique for end-to-side anastomoses has been developed in a rat carotidto-carotid model. Reliability of the technique was
BRITISH MICROSURGICAL
425
SOCIETY MEETING 1983
tested in a series of ten consecutive animals. After two days (one animal) or three weeks (nine animals) all anastomoses were patent at a second Histology (Dr M. H. Bennett, operation. Northwood) confirmed patency and showed no anastomotic stenosis or thrombosis. Continuous sutures would seem to be especially suitable when there is limited access to the posterior wall of an anastomosis or when anastomosing the larger vessels now employed in free flap and other reconstructive surgery. Two points raised in the discussion should be noted. First (Prof. R. D. Acland, Louisville), one
should try to avoid difficulties such as anastomoses with limited access. Second (Mr D. R. Bird, Edinburgh), at least some interrupted sutures are needed if dilatation of the anastomosis is for with dialysis example anticipated, arteriovenous fistulas, extra-cranial intra-cranial revascularisation and paediatric microsurgery.
Reference Timmons, M. J. (1984). Continuous sutures for micro-arterial end-to-side anastomoses. Plastic and Reconstructive Surgery (In press).
The mechanisms of flap oedema following control with salbutamol
free transfer in man and its
A. G. BATCHELOR,
G. S. BASRAN,
J. G. HARDY, D. PEARSON and L. SULLY
Departments
Surgery,
and Medical
of Plastic
Medicine
The ischaemia and manipulation of free flap transfer engenders acute inflammation. The final common path of this mechanism is a cell-rich exudative oedema occurring from the microcirculation. All free flaps swell to some degree after transfer.
Materials and methods This phenomenon and its modification with the drug salbutamol has been studied in human subjects using a double radioisotope technique. Technetium 99 m was used to label the red cells, and Indium 113 m was used to label the plasma transferrin as an indicator of plasma protein. Observations were made of a free flap after it had been raised, and after it had been transferred. The post-transfer measurements were in two phases,
Physics,
Nottingham
Group of Hospitals
firstly before, and secondly after, the administration of 250 micrograms of salbutamol intravenously. The Technetium counts were an index of the red cell mass within the flap and the Indium counts an index of the plasma protein within the flap. Any disproportionate increase of Indium over Technetium indicated the formation of exudative oedema. Results These showed that flap oedema occurs as soon as a flap is raised, that the rate of formation increases after the period of ischaemia necessary for free transfer and that intravenous salbutamol appears to reduce and in some cases abolish, the formation of oedema following its administration. Salbutamol did not affect flap blood flow.