Biomedical subjects

G Gherardini

Publications and source records attributed to G Gherardini.

27 records · Page 2Linked to original sources

PubMed1995

Severe peripheral ischemia after vasospasm may be prevented by spinal cord stimulation. A preliminary report of a study in a free-flap animal model.

Electric spinal cord stimulation (SCS) is at present used in many centers to treat ischemic pain and ischemia in peripheral vascular disease. The most promising results have been obtained in cases where a vasospastic component is dominating. The knowledge concerning the mechanisms behind these effects has been scanty, but recent experimental studies indicate that suppression of sympathetic activity and the release of vasoactive substances may be important. A problem with many of the animals studies aimed at exploring these mechanisms is that they have almost exclusively been performed on normal animals without ischemia. However, in studies of the responsiveness of local ischemia to various pharmacological substances and to electrical transcutaneous nerve stimulation, animal models with ischemic skin flaps have been used. We applied SCS via chronically implanted electrodes in a model of local vasospasm in the rat, induced by mechanical stimulation of the vessel supplying an island flap in the groin. Male Sprague-Dawley rats were used. First, a monopolar system for spinal cord stimulation, with the intraspinal cathode at vertebral level T11, was implanted in halothane anaesthesia. After about three days of recovery the rats were anaesthetized with chloral hydrate ip and a groin neurovascular flap based on the epigastric vessels was raised. Microcirculation in the flap as well as in a control area in the contralateral groin was monitored by laser Doppler technique. Vasospasm was induced by gently pinching the superficial epigastric artery with microforceps. Two groups of animals were submitted to two spasm periods, one with SCS applied for 20 min. by 50 Hz; 0.2 msec and with 2/3 of the intensity required for a motor response before the first period. The second group, receiving sham SCS, served as a control. Both degree of ischemia after spasm provocation and the time to recovery were evaluated. In general SCS affected basal flow very little. In the control group the rats demonstrated increasing vasospastic reactions with subsequent flap ischemia to the two mechanical provocations. In the experimental group a response pattern emerged indicating that pre-spasm SCS could both reduce the spasm amplitude and significantly shorten the time for restoration of a satisfactory microcirculation in the flap. Some few trials with pharmacologically induced spasm by topical application of noradrenaline onto the feeding vessel also followed the same pattern. In conclusion, SCS seems to be able to reduce vasospasm, especially if the treatment is given before the ischemic period. This approach may supply an animal model for further studies of possible mechanisms behind the microcirculatory effects of SCS.

Animals↗

PubMed1995

Effects of calcitonin gene-related peptide and lidocaine on mechanically-induced vasospasm in a rat island flap.

A neurovascular island flap based on the superficial epigastric vessels was raised in 59 rats. Blood flow in the flap was recorded continuously with a laser Doppler flowmeter. Complete vasospasm was induced mechanically in the artery by pinching it. Calcitonin gene-related peptide (10(-7) M), lidocaine 2 percent, lidocaine 20 percent, or sodium chloride 0.9 percent were applied topically to the vessels in order to relieve the vasospasm. In 18 arteries, spasm was induced a second time after the resolution of the first vasospasm. Calcitonin gene-related peptide significantly shortened the time to reach 50 percent of the original blood flow and increased the final blood-flow values 30 min after mechanically-induced vasospasm, in comparison with pre-spasm values, and significantly increased the number of flaps in which the blood-flow values were restored to pre-spasm levels. Lidocaine did not significantly change the time to reach 50 percent of the original blood-flow values and the number of flaps recovering to pre-spasm blood-flow levels, or the final levels after vasospasm, in comparison with saline. It was concluded that, in this model, calcitonin gene-related peptide, but not lidocaine, increased blood flow after mechanically-induced vasospasm.

Animals↗

PubMed1995

Calcitonin gene-related peptide increases microcirculation after mechanically induced ischemia in an experimental island flap.

Vasoconstriction, as a result of mechanical manipulation of blood vessels during microsurgery, may produce a decrease in blood supply and endanger flap viability. A study was undertaken to determine the effects of the topical vasodilator calcitonin gene-related peptide on the microcirculation of flaps after mechanically induced ischemia. A neurovascular island flap based on the superficial epigastric vessels was raised in 42 rats. Blood cell flux in the flap was recorded continuously with a laser Doppler flux meter. The feeding artery was pinched to induce vasospasm, and different concentrations of calcitonin gene-related peptide (10(-7), 10(-8), 10(-9), 10(-10) mol) or a control of sodium chloride 0.9% was applied topically to relieve the ischemia. Results showed that calcitonin gene-related peptide at a concentration of 10(-7) mol significantly shortened the time to reach 50% of the original blood cell flux values (270 +/- 123 seconds) and significantly increased the number of flaps in which the blood cell flux values were restored to prestress levels within 30 minutes. The data support the conclusion that, in this model, topical calcitonin gene-related peptide at the concentration of 10(-7) mol was effective in promoting recovery of the microcirculation after mechanically induced ischemia, without the adverse effects associated with other commonly used vasodilators.

Animals↗

PubMed1995

Comparison of vascular effects of ropivacaine and lidocaine on isolated rings of human arteries.

Ropivacaine is a new local anaesthetic agent. Previous animal studies have indicated that vasoconstrictor effects are elicited by ropivacaine in vitro and subcutaneously and that it produces blanching of the skin if injected subcutaneously in humans. Lidocaine is a widely used local anaesthetic reported to exert a biphasic effect on the microvasculature with contraction at low concentrations and relaxation at high concentrations. There is a need for pharmacologic tools able to counteract local arterial vasoconstriction. In this study, the contractile effect of ropivacaine and lidocaine were investigated in vitro on isolated human arteries. Experiments were performed on 43 internal mammary artery (IMA) rings obtained from 22 patients and on 14 radial artery (RA) rings from 7 patients. The rings were mounted in organ baths and isometric contractile activity was measured. Experiments were conducted by cumulative adding ropivacaine or lidocaine (1.5 x 10(-5) M; 4.5 x 10(-5) M; 1.5 x 10(-4) M; 4.5 x 10(-4) M; 1.5 x 10(-3) M; 4.5 x 10(-3) M; 1.5 x 10(-2) M) to the organ baths. The endothelium was mechanically removed in 19 IMA rings and in 9 RA rings. Ropivacaine and lidocaine produced a biphasic response with contraction at low concentrations (1.5 x 10(-5)-1.5 x 10(-3) M) and release of the maximal contraction at higher concentrations. No statistically significant differences in contractile or relaxing effects were seen between the two drugs. Removal of the endothelium did not significantly affect contractile activity. In this study of human mammary artery preparations, ropivacaine is not a stronger vasoconstrictor than lidocaine.

Amides↗

PubMed1995

Preemptive spinal cord stimulation reduces ischemia in an animal model of vasospasm.

Spinal cord stimulation (SCS) has been increasingly used in the treatment of ischemia caused by obliterative diseases in the extremities and in the cardiac circulation. The most promising effects have been obtained when physicians suspect that a major vasospastic component underlies the ischemic symptoms (e.g., as in Raynaud's disease). Despite the clinical success of this treatment method, little is known about the mechanisms underlying the pain relief it produces and its anti-ischemic effects. Most earlier experimental studies have used normal animals or animals with cerebral vasospasm induced by injection of autologal blood into the cerebrospinal fluid space. In the present study, we applied SCS in a rat model via implanted electrodes to study the effect of preemptive stimulation on the ischemia caused by vasospasm in a neurovascular flap in the groin; the vasospasm was induced by mechanical pressure applied to the feeding artery. In rats treated with SCS, delivered with parameters similar to those used clinically, the percentage of flaps recovering normal microcirculation after the spasm was significantly higher than in the untreated control group (100 and 28%, respectively; P < 0.05), and the maximal blood flow after the ischemic episode was significantly higher in the SCS group than in the control group (127 and 51 arbitrary units, respectively; P < 0.05). The percentage of animals regaining the premanipulation circulation after the provocation of a second spasm was also greater in the SCS-treated group than in the control animals (50 and 14%, respectively; P < 0.05). Pilot studies showed that this protective effect was specific to SCS given before spasm induction, an observation corroborated by clinical experiences.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Intradermal lignocaine injections increase blood cell flux but not flap survival in rats.

In four groups of six rats a random dorsal flap was raised, and 5, 20, or 200 mg/ml lignocaine or 0.9% sodium chloride, were injected intradermally. Cutaneous laser Doppler blood cell flux was measured at 12 time points over 130 minutes. In six other groups 5, 20, 100, 200, or 400 mg/ml lignocaine concentrations, or sodium chloride were tested. Blood cell flux was measured at the time that the flap was raised and 30 minutes after the injections. The area of the flap that survived was measured on day 10. Raising of the flaps resulted in a significant reduction in blood cell flux, which was followed by a significant increase at 10 minutes (p < 0.05) after the injections with all lignocaine concentrations tested. Injections of 5, 20 and 100 mg/ml lignocaine elicited a significant increase (p < 0.05) in blood cell flux compared with baseline values. There was no reduction in blood cell flux values at any concentration of lignocaine tested. Compared with sodium chloride, injections of lignocaine had no significant effect on flap survival. We conclude that, despite an increase in blood cell flux, lignocaine had no effect on flap survival in this model.

Animals↗

PubMed1994

Pedicled compared with free transverse rectus abdominis myocutaneous flaps in breast reconstruction.

Two groups of patients who had undergone breast reconstruction with the transverse rectus abdominis myocutaneous (TRAM) flap after modified radical or partial mastectomy were evaluated. The type of reconstruction was either pedicled (n = 27, one of which bilateral) or free flap transfer (n = 11). In both groups there were both primary and secondary reconstructions. Flap complications were more common with the pedicled TRAM flap. There were nine partial flap necroses in the pedicle group, but only one in the free flap group. The only flap loss was a pedicled flap. In the free flap group, revision of the anastomosis was required in two patients. The free TRAM flap took longer to do than the pedicled flap. In conclusion, the two procedures yield acceptable results, but the free TRAM flap seems to be safer than the pedicled flap, thanks to the better blood supply from the inferior epigastric artery. It also allows greater freedom and versatility in moulding the reconstructed breast.

Female↗

PubMedDate not supplied

Immediate breast reconstruction with the transverse rectus abdominis musculocutaneous flap after skin-sparing mastectomy.

Immediate breast reconstruction with the transverse rectus abdominis musculocutaneous (TRAM) flap after skin-sparing mastectomy is becoming an increasingly performed procedure in patients with ductal carcinoma in situ, early invasive breast cancer, and prophylactic mastectomy. Through a periareolar approach, it is possible to remove the breast parenchyma along with the nipple areola complex, preserving almost all the original skin envelope and the inframmamary fold. The TRAM flap is used to recreate the volume and shape of the original breast. This technique has higher quality and easier reconstruction. The major disadvantages, extensive scar and donor site skin color mismatch, are reduced to a minimum level because the former is limited at the natural border of the nipple areola and the latter can be effectively concealed with proper nipple reconstruction. Thirty-one patients with a mean age of 39 years (range, 26-50 years) who had undergone unilateral or bilateral mastectomy for early breast cancer and immediate breast reconstruction with the pedicled TRAM flap were retrospectively reviewed. Requirements for the skin-sparing mastectomy technique include suitability of donor site tissue for autologous tissue, early breast cancer or ductal carcinoma in situ, and adequate size and shape matching of the contralateral breast. There was no observed local recur- rence during the follow-up period (mean, 20 months; range, 11-30 months). Complications at the recipient site include mastectomy skin flap partial necrosis in 2 patients and cellulitis of the transferred flap in 1 patient. No total or partial flap necrosis was observed. One patient developed abdominal bulging 1 month after the operation, during the administration of chemotherapy. All reconstruction was considered very satisfactory from an aesthetic perspective by the surgeon and the patient. The nicer aesthetic result with oncological safety is achieved with immediate breast reconstruction with the TRAM flap after skin-sparing mastectomy. The risk of local recurrence is not higher compared with more radical surgical techniques.

Adult↗

PubMedDate not supplied

[Fetal megacystis--prenatal diagnosis and attempt at therapy].

Dilatations of the fetal urinary tract are suspect for obstructions. An extremely dilated bladder may also point to an innervation disorder. In the here presented case a very rare disease is the cause for the dilatation of the fetal bladder, the Megacystis-Microcolon-Hypoperistalsis-Syndrome. No mature ganglionic cells are detectable in the bladder wall histologically. Up to now eight cases have been reported, all female neonates died within the first days after birth. Our presented child - also a female - is now more than one year old, but artificial feeding is still necessary.

Catheters, Indwelling↗