Microvascular anastomosis with a low-output carbon dioxide (CO2) laser. II. Histopathological features

A low-output CO2 laser was applied for microvascular anastomosis. The healing process of the vessel wall was examined histopathologically using light and scanning electron microscopes, and compared with that following conventional suture anastomosis. A power level of 21-40 mW and an exposure time of 5-15 sec were used. Under these conditions the laser beam reached the adventitia and media but not the intima. This made it possible to perform microvascular anastomosis without causing damage to the intima. Inflammatory reactions in the vessel wall were milder and endothelialization of the lumen surface occurred somewhat earlier with the laser technique than with the conventional technique of manual suture anastomosis.     

Quantitative assessment of low blood flow using an electromagnetic flowmeter

This study evaluated the behavior and reliability of an electromagnetic flowmeter for the quantitative assessment of low mean blood flow. Cuff-type probes with lumen diameters of 0.75, 1.0, 1.5, and 2.0 mm were used on excised canine vessels of external diameter less than 4.0 mm for in vitro calibrations. Flows ranged from 0 to 30 ml/min. Standard calibration plots were linear through zero with a mean error of ± 4.2%. Linear plots were significantly shifted by vascular constrictions of 50% and greater. Mechanical occlusion of the vessel for zero baseline determination was found to be important. To date, this report is the most extensive and accurate quantitative study of low blood flow with small transducers. We feel that the equipment can function as a valuable surgical tool.     

The morphology and patency of arterial and venous microvascular anastomoses throughout the first post-operative year. A histological study

End-to-end microvascular suture anastomoses, 40 arterial and 41 venous, from the rabbits carotid artery and posterior facial vein were harvested at 5 different time intervals (1, 2, 3, 6 and 12 months) post surgery and evaluated with light microscopy. A 100% long-term patency was noted both in arteries and veins. Quantitative measurements of the width of the vessel wall components indicated that a statistically significant temporary hypertrophic response occurred in the arterial intima, culminating in the third month when the width of the vessel wall at the anastomotic level almost doubled the normal. After that the width of the vessel wall again declined but it remained thicker than the adjacent vessel wall at one year post surgery. Among the venous anastomoses, however, the wall thickness at the anastomotic level remained thinner than the adjacent vessel wall throughout the evaluation period. The original vessel wall characteristics are not restored at the anastomotic site with intimal hyperplasia compensating for medial necrosis. Despite these events a technically satisfactory microvascular anastomosis should remain patent for years.     

Microsurgical reconstruction of the hepatic and superior mesenteric arteries using a back wall technique.

During the last seven years, 17 patients underwent microsurgical reconstruction of 14 hepatic and four superior mesenteric arterial systems following extended pancreatectomy or hepatectomy, and in living-related liver transplantations (LRLT). All microvascular anastomoses in this series were performed using a back wall technique, in which the microsutures are placed in the back wall of the vessel first, and turning over of the microclamp is eliminated. This back wall technique is useful for microvascular reconstruction in a deep abdominal cavity in which there is no room to turn over the microclamp. In LRLTs, even if the hepatic artery of the graft liver is so short that the microclamp on it cannot be rotated, this technique overcomes such difficult situations. Microvascular anastomosis without turning over the clamp is superior to the conventional method in terms of reducing intimal damage to the vessels. The vessels located vertical to the microvascular surgeon are smoothly anastomosed using this technique. The authors advocate this back wall technique as advantageous in microsurgical reconstructions of the hepatic and superior mesenteric arterial systems.     

Microvascular anastomosis with minimal suture and Arista: an experimental study

BACKGROUND: The conventional technique of microvascular anastomosis may cause trauma to the vessel wall. In addition, the technique is difficult for beginners and is time consuming. The duration of ischemia is an important limiting factor for muscle transfer. In the case of multiple-digit replantations, fatigue developed in the surgeon may also result in suboptimal results. This study was performed to establish an easier and shorter method of microvascular anastomosis using the Arista hemostatic agent. METHODS: In this study, 20 carotid arteries obtained from rats were equally divided into two groups. The arteries were then divided and repaired using three simple interrupted stay sutures with Arista powder. Evaluations were performed using the following three methods: (1) clamping time during the vessel anastomosis, (2) patency test (after 1 hour, 24 hours, and 28 days), and (3) light microscopic findings. RESULTS: The clamping time in the conventional suture anastomosis group was 21+/-4 minutes, whereas that of the minimal suture in the Arista group was 12+/-2 minutes; the difference between the two groups was statistically significant (P<.001). There was no significant difference between the patency rates of the two groups (P= .474). It was observed that the Arista group showed qualitatively less perivascular foreign-body giant cell reaction than the control group. There was no evidence of vascular mural fibrinoid necrosis, indicating that Arista was nontoxic for the vessel walls. CONCLUSIONS: The Arista-assisted microvascular anastomosis is an alternative to the conventional suture-only method because it reduces the anastomosis time significantly and does not cause narrowing of the vessel wall. We believe that this technique has the potential for improving the performance of microvascular anastomosis in clinical practice.     

Small vessel disease after heart transplantation: impact of immunologic and nonimmunologic risk factors*

To determine risk factors for small vessel disease after heart transplantation (HTx), characteristics of donors and organ harvesting were evaluated in 246 HTx patients (205 male, 41 female, mean survival 5.4 years). In right ventricular endomyocardial biopsies (EMB, n = 5421) evidence of microvascular disease [endothelial cell (EC) swelling/vessel wall thickening] was evaluated by light microscopy (hematoxylin and eosin staining, ×200). Mild EC swelling/vessel wall thickening were found in 204 and 213 patients, severe EC swelling/vessel wall thickening were present in 23 and 142 patients respectively. Evidences of mild and severe acute cellular rejection were found in 2064 and 421 EMB respectively. Microvascular disease was positively correlated with mild acute rejection episodes (P < 0.05). EC swelling was more frequent in patients with donors dieing of craniocerebral trauma. No correlations were present to further demographical data. Microvascular alterations after HTx seem to be the result of an immunologic conflict rather than to depend on nonimmunologic factors.     

Novel microvascular anastomosis between a single vessel and two downstream vessels

Microsurgeons rarely encounter a situation that includes multiple downstream arteries requiring reperfusion with only one feeding artery being available. To cope with the difficulty of such a case, a unique microvascular anastomosis is described. This surgical technique is based on the assumption of the presence of a single large outflowing vessel and two small downstream vessels. The axial incisions were made on the cut end of the two small vessels. The ends of the two small vessels were sutured side-to-side and remodeled as one vessel. The partially coalesced small vessels were then anastomosed with the outflowing large vessel in an end-to-end fashion. Case presentation: a crush injury of the foot required reconstruction of the blood flow. The first dorsal metatarsal artery (FDMA) was damaged and occluded by thrombosis. The first and second toes had no blood supply. The original plan was simply to remove the damaged area of the FDMA and replace it with a straight vein graft, as the bifurcation to the two digital arteries appeared to be intact. At the time of microvascular anastomosis, however, the FDMA was found to still be damaged, and it required additional debridement. As a suboptimal method, the vein graft and the two digital arteries were anastomosed by the above-described atypical method. The digits all survived, and the patient subsequently returned to work, with no complications as of 10 months postoperatively. This atypical microvascular anastomosis is not an established method, but it has potential utility in similar situations.Level of Evidence: Level V, therapeutic study.     

Increasing the flow output by Y-shaped microvascular anastomosis

In this paper the authors present a new type of microvascular anastomosis to overcome two major inconveniences in microsurgery: "flow discrepancy" and vessel size discrepancy between the donor and the recipient vessels. A Y-shaped anastomosis is an end-to-end anastomosis between three vessels: two small ones on one side and a larger vessel on the opposite site. Both arterial and venous anastomoses can be performed in this way. The blood flow can go across the anastomosis in both directions. Hemodynamically, this increases the blood output through the anastomosed vessels. The surgical technique and main clinical applications of the Y anastomosis are described in detail. Indications and advantages are discussed.     

Long-term performance of a hand held spirometer.

BACKGROUND: A study was undertaken to test the long term performance of a small hand held spirometer for self-administered serial spirometric testing. METHODS: Thirty turbine pocket spirometers (MicroMedical DiaryCard) were used in a clinical trial on 22 emphysematous patients with severe alpha 1-antitrypsin deficiency. The spirometers were able to store the date, time, forced expiratory volume in one second (FEV1), forced vital capacity (FVC), peak expiratory flow (PEF), and flow-volume loop for each blow. Every four weeks when the patients came for alpha 1-antitrypsin infusions the performance of their spirometer was checked before and after retrieval of the data from the spirometer. Calibration checks were threefold and included volume calibration with a 1.0 litre and 3.0 litre syringe, and flow calibration with a decompression calibrator. RESULTS: After two years of study the mean number of spirometric recordings performed per spirometer was 693 (range 237-1178), and the mean number of calibration checks was 33 (range 2-57). The coefficient of variation of the calibration signal was 1-2% for syringes and 0.5-1% for the decompression calibrator. The bearings of one turbine exhibited excessive friction after 17 months. None of the other 29 instruments showed drift, and a general drift of all spirometers towards larger or smaller readings could not be shown. However, unforeseen problems in the stability of the calibrating devices were observed. CONCLUSIONS: The small hand held turbine spirometers are suitable for long term patient-administered serial spirometric testing. The two year durability is acceptable and the long term reproducibility excellent.     

Neurosurgical embryology. Part 8: Post-natal angiogenesis and remodeling

Post-natal angiogenesis (microvascular proliferation) and remodeling (modifications of diameter and wall thickness) occur in various physiological circumstances including adaptation to exercise or wound healing. The formation of a new vessel is submitted to the combinative action of growth factors. New endothelial cells migrate, proliferate, differentiate and attract pericytes and future smooth muscle cells to create the new vessel. Powerful stimuli leading to remodeling and to the creation of new vessels are mainly represented by hemodynamic forces generated by pressure and blood flow, and by hypoxia. Our purpose is to overview the molecular mechanisms and the stimuli giving rise to these processes.     

Steady and pulsatile flow fields in an end-to-side arterial anastomosis model

We investigated the flow field within a rigid-walled in vitro model of an end-to-side 45 degree anastomosis in an attempt to identify possible hemodynamic factors that may contribute to the pathogenesis of distal anastomotic intimal hyperplasia. A high-resolution photochromic tracer technique was used to visualize the flow in orthogonal planes and to determine the axial wall shear stress profiles for both steady and pulsatile flows over a range of physiologically relevant conditions. The flow field showed qualitative similarities to those seen in curved vessel: rapidly moving fluid from the graft section affects the bed of the host vessel, that is, the wall opposite the anastomosis, eventually advancing down the host vessel in a spiraling motion. A small mobile separation zone was noted at the toe of the anastomosis. Comparison of wall shear stress profiles with previously reported preferential sites for the development of intimal hyperplasia supported a low wall shear stress and/or flow separation pathogenesis hypothesis. One notable exception was the bed of the host artery that appeared to be subjected to a complex hemodynamic environment.     

BLADDER MICROVASCULATURE IN WOMEN WITH INTERSTITIAL CYSTITIS

PURPOSE: A cardinal cystoscopic finding in women with interstitial cystitis is mucosal small vessel hemorrhage or glomerulations after hydrodistention. We quantified and compared microvascular density and endothelial proliferation in the bladder biopsies of women with interstitial cystitis and a control group of women who were undergoing incontinence or prolapse surgery. MATERIALS AND METHODS: We performed computer assisted image analysis and immunohistochemical studies to compare differences in the blood vessel count, and proportional area in the bladder suburothelium and deeper submucosa of bladder biopsies of 52 women, including 26 with interstitial cystitis. Routine light microscopy features were examined and correlated with microvascular density. RESULTS: In the bladder biopsies of women with interstitial cystitis there was a lower blood vessel count (p = 0.01), and a lower proportion of the total image consisted of blood vessel wall (p = 0.03) in the suburothelium than in control biopsies. We noted no difference in the blood vessel count of the deeper submucosa or in the degree of endothelial cell proliferation. Suburothelial blood vessel differences correlated with the degree of histological change, such as edema, inflammatory infiltrate and vascular congestion. CONCLUSIONS: We found decreased microvascular density in the suburothelium but not in the deeper submucosa in bladder biopsies of women with interstitial cystitis.     

Long term evaluation of the unilink anastomotic system. A study with light and scanning electron microscopy.

The long term effects of the Unilink mechanical microvascular anastomosis in terms of anastomotic patency and histological changes in the vessel wall were evaluated in 10 rabbits. Both carotid arteries and facial veins were divided and reanastomosed with the Unilink device. At death two years later all 40 anastomoses were fully patent, with histological changes similar to those described previously after 16 weeks, that is, normal endothelial lining, but almost total atrophy of the media at the anastomotic site. The thinning of the vessel wall at the anastomosis caused neither occlusions nor aneurysms during the observation period.     

Effect of tamoxifen on arterial microvascular anastomosis

Breast reconstruction after cancer treatment is based on the circulation of pedicle and microvascular flaps. This article aimed to verify the effect of tamoxifen (TMX) pretreatment in arterial anastomosis in rats. Twenty female Wistar rats were equally divided into two groups. TMX (0.3 mg/kg) was administered to the experimental group for 2 weeks orally. After this period, the right femoral artery was sectioned and a terminoterminal anastomosis performed. The same procedure was done in the control group, except that the animals received the vehicle without TMX. One week later, the femoral arteries were inspected for flow through the anastomosis, and the vessel near it was sent to light microscopic examination. It was observed mild vasculite in both groups. The intimal thickness and total vessel wall in the TMX-treated group was significantly higher. A real thrombotic effect upon the arterial vascular anastomosis was not observed, eventhough, TMX induced intimal hyperplasia.     

Die Anwendung von Prostaglandin E1 bei mikrovaskulären Rekonstruktionen der oberen Extremität nach Akuttraumen

The operative treatment of hand and upper extremity trauma with injury of main vessels becomes a daily standard work in trauma and microsurgical replantation centers. The techniques of vessel and soft tissue reconstruction are well known. The outcome of the replantation depends on various factors. Main influences are the intraoperative status of the vessel wall and the unobstructed flow in the vessel after the operation. Another factor for successful replantation is the homeostasis of the patient. It can be influenced by many drugs which are applied according to a replantation schema. Aim of this therapy is the correction of the rheologic properties of a patient. In a patient group of 25 treated with Prostaglandin E1 (Prostavasin) we observed better wound healing with a 80% rate of successful replantation and microvascular vessel reconstruction.     

Determinants and genesis of canine pneumocardiogram

The pneumocardiogram measures the to-and-fro movement of gas from the lung with each heartbeat during apnea. Six mongrel dogs were prepared with chronic ascending aortic or pulmonary artery flow probes, corresponding occlusion cuffs and intraventricular pressure transducers. Under halothane anesthesia, the flow pneumocardiogram (PnCG) and its time derivative (acceleration pneumocardiogram or dPn/dt) were transduced during apnea by a small high-gain pneumotachograph. All variables were recorded on paper. The effects on the pneumocardiogram of great vessel occlusion, changes in cardiac loading, small airway patency, and chest wall integrity were investigated. Four of the animals were treated subsequently to produce a chemical cardiac denervation and restudied. The systolic component of the dPn/dt which correlates with myocardial contractility (IJ wave) was dependent primarily on left ventricular (LV) ejection, markedly affected by cardiac preload and modified by afterload changes to a lesser degree. Small airway closure obliterated the wave form, while opening the chest wall attenuated the dPn/dt IJ wave by 25%. This study shows the dPn/dt IJ wave is anatomically related to LV performance and responds to changes in LV function similar to other noninvasive cardiac measurements.     

A modified technique of end-to-side microvascular anastomosis for the posterior wall

A modified technique of interrupted suturing for the posterior wall in end-to-side microvascular anastomosis is presented. It has advantages, especially for the suturing of the pedicle vein and the internal jugular vein in head and neck reconstructions when the pedicle vessel is so short that it cannot be turned over to expose the posterior wall. The pedicle vein is located vertical to the internal jugular vein, and the first stitch begins at the left end of the vessels for a right-handed person. To facilitate the exposure of the left edge of the vessels, the donor vessel is rotated approximately 90 degrees. The advantage of our technique is clear visualization of each suture by rotating the pedicle vessel. Subsequent to the interrupted suturing of the posterior wall, the anterior wall can be sutured by conventional methods. This modified technique is useful for end-to-side microvascular anastomosis, which the microsurgeon may find useful.     

Thermal effects of stationary "hot tip" laser coronary probes: an in vitro assessment

Percutaneous laser thermal probe angioplasty requires sufficient laser probe flexibility to access the coronary tree. This may entail a loss of axial strength and the resultant slow advancement may lead to unwanted heating of the normal coronary artery proximal to the lesion. To assess the lateral thermal effects of stationary coronary laser probes, laser thermal energy (50-150 J) was delivered to 25 coronary artery segments (diameter 1.9-4.0 mm) in a perfused cadaver heart preparation using a 1.7 mm tip probe. Adherence to the vessel wall occurred in 19 segments, endothelial charring in 8 segments, and perforation in 3 segments. Endothelial charring was seen in 8 of 13 nonperfused segments but in 0 of 12 segments perfused at 60 ml/minute (P less than 0.01). In all three perforations the vessel to probe diameter ratio was less than 1.6:1, perfusion was absent, and traction to dislodge the adherent probe was necessary. Lateral wall damage is a complication of stationary laser probes: smaller-tipped probes which are advanced rapidly at the time of energy delivery may enhance the safety margins of coronary laser thermal probe angioplasty.     

Long-term result of arterial grafts interposed for arterial defects using the telescoping anastomotic technique: histological and angiographic study.

The arterial grafting model for arterial defects provides an ideal environment for the microvascular telescoping anastomosis because tension of the repaired vessel is maintained low and deformities of the inserted vessel end is minimal due to the thick arterial wall. The left femoral artery was grafted in 46 rats into the defect created in the right femoral artery using the telescoping anastomotic technique at both the proximal and distal anastomoses. The grafts were seen histologically and angiographically 3 to 4 months postoperatively in order to fairly evaluate the telescoping anastomosis in terms of long-term patency, stenosis, and changes in the outer and inner walls at the anastomosis. All arterial grafts were patent 3 to 4 months postoperatively and there were no aneurysms at the anastomoses. Enlargement of the graft diameter was minimal. The rate of stenosis at the anastomosis was smaller than that 1-day postoperatively. Even though the thick arterial wall was initially inserted and the intimal hyperplasia was still present at the anastomosis 3 to 4 months postoperatively, the long-term stenosis was relatively mild due to the atrophy in the overlapped walls.     

A new probe for the anastomosis of small vessels.

We developed new probes with three varying sizes (phi1.0, 1.5 and 2.0 mm) with a trench for guiding the needle which made small vessel anastomoses easy and suture placement accurate with clear identification of the vessel lumen. We evaluated the efficiency of these probes on anastomoses using the bilateral common carotid arteries of cadaver rabbits. The anastomosis time of end-to-side anastomosis was shortened by using the probe from 20.2+/-3.3 to 15.4+/-2.6 min, and of side-to-side anastomosis from 20.2+/-1.3 to 16.0+/-1.2 min. Of the 5 end-to-side anastomoses without the probe, there was one deformity of the anastomoses site and of the 5 side-to-side anastomoses without the probe, there was one stenosis of the anastomosis. There were neither deformity nor stenosis of the 10 anastomoses of 5 end-to-side and 5 side-to-side anastomoses with the probes. In conclusion, the probe with a trench for guiding the needle made small vessel anastomoses easy.