Ultrastructural Investigations of Arterial Bypass Conduits after the Use of Different Harvesting Techniques Using an Electron Microscope.

OBJECTIVES: The aim of this study was to perform morphometric analysis of arterial conduits harvested by harmonic scalpel in coronary artery bypass grafting (CABG) patients. METHODS: From 100 CABG patients, 200 arterial conduits-100 radial arteries (RAs) and 100 left internal thoracic artery (LITAs)-were harvested. The patients had similar characteristics (mean age, sex ratio, comorbidities, etc.). We divided the patients into 2 groups according to harvesting technique. In group 1, a harmonic scalpel was used in 50 patients for harvesting arterial conduits (50 LITA and 50 RA). In group 2, conduits were harvested using low-voltage electrocautery. To prevent side effects of clipping, all conduits in both groups remained in perfused condition until anastomosis. A 10-mm length of conduit was cut for transmission electron microscopy investigation. We calculated duration of harvesting, blood flow changes, and histopathologic changes of the conduits according to a vessel scoring system. RESULTS: In the harmonic scalpel group, we detected pathologic findings-corruption of endothelial integrity, subendothelial damage, and endothelial pathology-in 5 specimens (10%) (3 LITA  [6%] and 2 RA [4%]). In group 2, pathologic findings were detected in 16 conduits (32%; 11 LITA, 22%, and 5 RA, 10%). Endothelial dissection, subendothelial disarrangement, cellular separation due to intercellular edema, and subadventitial hematoma were the main pathologic changes in the classic harvesting method. There was a significant difference between the groups (P = .001). Harvesting time of LITA was nearly similar in both groups: 26.9 ± 11.1 min (range 25-38) in group 1 and 21.3 ± 8.6 min (range 21-25) in group 2 (P = .049). RA harvesting time was significantly shorter with the harmonic scalpel technique (20.3 ± 3.9 versus 27.6 ± 5.4 min, P = .022). The blood flow of the conduits was similar, with no statistical difference for the 2 arterial conduits (LITA, P = .76; RA, P = .55). CONCLUSION: In the learning curve period, the use of a harmonic scalpel is time consuming and presents some difficulties during the harvesting of conduits. According to our study results, however, the harmonic scalpel technique may be useful because of decreased pathology, including spasm. In our opinion, graft occlusion or thrombus as a life-threatening condition and endothelial dysfunction may decrease with the use of this alternative harvesting technique.

Electron Microscopic Comparison of Radial Artery Grafts in Non-Diabetic and Diabetic Coronary Bypass Patients.

OBJECTIVE: We compared electron microscopic histologic changes of the radial artery grafts in non-diabetic and diabetic patients. METHODS: Thirty-six patients were divided into three groups according to their diabetic status (Group I had no diabetes mellitus [DM], Group II had type two DM and HbA1c levels were <7.5%, and Group III had type 2 DM but HbA1c levels were >7.5%). Distal parts of radial artery grafts were evaluated with scanning electron microscopy in a blind fashion by two histologists. Electron microscopic scores were compared among the groups. RESULTS: Radial artery electron microscopic scores were significantly different between group 1, 2 and 1, 3 and 2, 3 (p = 0.028, p < 0.001, and p < 0.001). In linear regression analysis, duration of DM (p = 0.027) and fasting plasma glucose (p = 0.001) were found as independent risk factors for histologic changes of radial artery grafts. CONCLUSION: Duration of DM and poor glycemic control were found to be associated with radial artery electron microscopic changes. doi: 10.1111/jocs.12761 (J Card Surg 2016;31:410-415).

Ultrasound evaluation of forearm arteries in patients undergoing percutaneous coronary intervention via radial artery access: results of one-year follow-up.

BACKGROUND: A proven advantage of radial over femoral arterial access has led to an increase in the number of interventions performed via radial artery access in patients with acute coronary syndromes. Both assessment of the pulse volume and the Allen's test are subjective and subject to investigator bias. An ultrasound examination of the forearm arteries provides important information about the anatomy of the forearm vessels, and indirectly also about the efficiency of collateral blood supply to the hand. It also enables determination of the relevant vessel diameter before the planned intervention, and may be used to assess local complications. AIM: To assess the morphology of forearm blood vessels and measure the diameter of both radial and ulnar arteries at the cannulation site using ultrasound imaging. We also aimed to identify potential vascular anomalies and local complications associated with radial artery puncture. METHODS: The study included 109 patients with cardiologic indications for coronary angiography or coronary angioplasty. An ultrasound evaluation of forearm arteries was performed prior to the intervention, and the vascular anatomy was later verified by angiography during the procedure. Ultrasound measurements of the vessel diameter were also performed and local complications of the cannulation were assessed. Measurements were performed immediately after the procedure and at 30 days and 12 months. RESULTS: Fifty-nine right and 50 left forearm arteries were evaluated. Women were 29% of the study population. The mean patient age was 59.2 ± 7.9 years. The mean diameter of the right radial artery was 2.17 ± 0.54 mm, and the mean diameter of the left radial artery was 2.25 ± 0.43 mm. The measurements revealed gender-related differences in forearm artery diameter (p = 0.003). Vascular anomalies of the radial artery were identified by ultrasound examination in 10% of subjects. A significant dilatation of the cannulated blood vessel was observed which lasted up to 12 months. An occlusion of the cannulated artery was demonstrated in 6.4% of patients. CONCLUSIONS: Ultrasound imaging is a reliable method to evaluate the diameter of forearm arteries and track their course in patients undergoing invasive cardiovascular procedures via radial artery access. The diameter of the radial artery by ultrasound evaluation is larger compared to that of the ulnar artery. The diameter of forearm arteries in women is smaller compared to men. A dilatation of the radial artery which may last up to 12 months develops following its percutaneous cannulation. Ultrasound imaging allows detection and monitoring of local complications such as radial artery occlusion. An unfavourable ratio of blood vessel diameter to the size of the used introducer sheath is a predictor of radial artery occlusion. Ultrasound imaging enables reliable evaluation of vascular anomalies involving the radial artery, especially within the distal forearm.

Pregnancy-induced remodelling and enhanced endothelium-derived hyperpolarization-type vasodilator activity in rat uterine radial artery: transient receptor potential vanilloid type 4 channels, caveolae and myoendothelial gap junctions.

In pregnancy, the vasculature of the uterus undergoes rapid remodelling to increase blood flow and maintain perfusion to the fetus. The present study determines the distribution and density of caveolae, transient receptor potential vanilloid type 4 channels (TRPV4) and myoendothelial gap junctions, and the relative contribution of related endothelium-dependent vasodilator components in uterine radial arteries of control virgin non-pregnant and 20-day late-pregnant rats. The hypothesis examined is that specific components of endothelium-dependent vasodilator mechanisms are altered in pregnancy-related uterine radial artery remodelling. Conventional and serial section electron microscopy were used to determine the morphological characteristics of uterine radial arteries from control and pregnant rats. TRPV4 distribution and expression was examined using conventional confocal immunohistochemistry, and the contribution of endothelial TRPV4, nitric oxide (NO) and endothelium-derived hyperpolarization (EDH)-type activity determined using pressure myography with pharmacological intervention. Data show outward hypertrophic remodelling occurs in uterine radial arteries in pregnancy. Further, caveolae density in radial artery endothelium and smooth muscle from pregnant rats was significantly increased by ~94% and ~31%, respectively, compared with control, whereas caveolae density did not differ in endothelium compared with smooth muscle from control. Caveolae density was significantly higher by ~59% on the abluminal compared with the luminal surface of the endothelium in uterine radial artery of pregnant rats but did not differ at those surfaces in control. TRPV4 was present in endothelium and smooth muscle, but not associated with internal elastic lamina hole sites in radial arteries. TRPV4 fluorescence intensity was significantly increased in the endothelium and smooth muscle of radial artery of pregnant compared with control rats by ~2.6- and 5.5-fold, respectively. The TRPV4 signal was significantly higher in the endothelium compared with the smooth muscle in radial artery of both control and pregnant rats, by ~5.7- and 2.7-fold, respectively. Myoendothelial gap junction density was significantly decreased by ~37% in radial artery from pregnant compared with control rats. Pressure myography with pharmacological intervention showed that NO contributes ~80% and ~30%, and the EDH-type component ~20% and ~70% of the total endothelium-dependent vasodilator response in radial arteries of control and pregnant rats, respectively. TRPV4 plays a functional role in radial arteries, with a greater contribution in those from pregnant rats. The correlative association of increased TRPV4 and caveolae density and role of EDH-type activity in uterine radial artery of pregnant rats is suggestive of their causal relationship. The decreased myoendothelial gap junction density and lack of TRPV4 density at such sites is consistent with their having an integral, albeit complex, interactive role in uterine vascular signalling and remodelling in pregnancy.

Comparative study on the histomorphology and molecular biology of radial artery conduits in patients with diabetes mellitus who underwent coronary bypass surgery.

We studied the impact of diabetes mellitus (DM) on the radial artery (RA) in 30 patients with DM and 30 non-diabetic patients undergoing coronary artery bypass grafting with autologous RA. RAs were recorded as normal if there was no cellular or stromal tissue between the endothelium and the internal elastic lamina. The RA was normal in 26.7% of diabetic and 76.7% of non-diabetic patients (p = 0.000298). Intimal thickness index and intima:media ratio were higher in the former than in the latter (p < 0.05; p < 0.05), with no significant difference in luminal narrowing (p > 0.05). Electron microscopy scores were lower in the non-diabetic group (p < 0.001); endothelial nitric oxide synthase (eNOS) protein expression and optical density were higher (p < 0.001). Von Willebrand factor and endothelin-1 messenger RNA (mRNA) levels were higher in the DM patients (p < 0.001). The quality of the RA in patients with DM was thus inferior to that in non-diabetic patients. Care should be taken when selecting RA as a conduit in patients with DM.

Comparison of ultrasonically activated scalpel and traditional technique in radial artery harvesting; an electron microscopic evaluation.

OBJECTIVE: Use of the radial artery (RA) as a conduit in coronary artery bypass grafting (CABG) has become increasingly popular in recent years. The aim of this prospective randomized study is to determine how the endothelial wall and blood flow of RA are differently affected with the usages of ultrasonic scalpel and conventional electrocautery in addition to effects of hypothermia and storage solutions. Histopathologic study was achieved by electron microscope to evaluate endothelium of the grafts. METHODS: Between 2008 and 2009, 182 patients with coronary artery diseases were operated for coronary artery revascularization. The radial arteries were harvested for 40 of these patients and divided into two groups depending on the use of the ultrasonic cautery (UC) (n=20) and the high-frequency electrocautery (EC) (n=20). Patients were divided into two subgroups according to the storage media of the graft. RA was preserved in situ at room temperature (Group 1) and normothermic organ bath (NOB) (Group 2). Harvesting time, use of hemostatic clips, frequency of spasm, in situ free flow, temperature and endothelial damage were compared between the two groups. Statistical analysis was performed using one-way ANOVA, Friedman and unpaired t tests. RESULTS: In all groups, blood flows were significantly decreased as parallel to the local temperatures. Second and third phase flows were similar in group EC1 and UC1 (p>0.05). Free flow was increased in group UC+NOB when comparing with only EC group (60.4±9.83 ml/min and 40.8±7.50 ml/min, p<0.001), whereas the graft preparing time "t2" was shorter in group EC than UC (10.9±2.42 min and 15.2±1.31 min, p<0.01). Nonetheless scoring of the groups in terms of endothelial cell structure and mitochondrial morphological changes did not show any significant difference. CONCLUSION: If endothelial integrity of the RA can be preserved along with the application of systemic temperature (NOB), regardless of harvesting technique, it provides better flow rates.

[Comparative study on the ultrastructure of radial artery in elderly patients underwent coronary artery bypass grafting with diabetes mellitus].

OBJECTIVE: To explore the impact of age and diabetes mellitus (DM) on the ultrastructure of radial artery (RA). METHODS: From June 2009 to December 2010, 64 patients underwent coronary artery bypass grafting (CABG) with autologous RA: 14 patients aged beyond 65 years without DM [9 male patients and 5 female patients, age (70 ± 4) years] and 18 patients aged beyond 65 years with DM [11 male patients and 7 female patients, age (68 ± 5) years], 20 patients aged under 60 years without DM [13 male patients and 7 female patients, age (53 ± 5) years] and 12 patients aged under 60 years with DM [7 male patients and 5 female patients, age (51 ± 6) years]. Four groups were subjected to routine electron microscopic examination and transmission electron microscopic examination. RESULTS: There were significant differences in percentage of endothelial denudation among four groups according to scanning electron microscopic evaluation (χ² = 18.082, P = 0.000). To compare with each other, there were significant differences between DM elderly patients and non-DM elderly patients, also between DM young patients and non-DM young patients according to scanning electron microscopic evaluation. There were no significant differences between DM elderly patients and DM young patients, also between non-DM elderly patients and non-DM young patients. Foam cells and the tendency of smooth muscle cells moving to intima could be visualized in DM patients according to transmission electron microscope. According to semiquantitative electron microscopic evaluation, non-DM young patients got the lower total scores than DM young patients (1.32 ± 0.20 vs. 4.38 ± 0.30) while non-DM elderly patients got the lower total scores than DM elderly patients (1.43 ± 0.20 vs. 4.67 ± 0.30). According to factorial design, there were significant differences between DM patients and non-DM patients (F = 41.22, P = 0.000). There were no differences between elderly patients and young patients (F = 1.24, P = 0.270). There is no interaction (F = 1.05, P = 0.309) between age and DM. CONCLUSIONS: After preoperative assessment with modified Allen's test and Doppler analysis, RA used as graft in the elderly has similar quality and function with young patients, and it may lead to a high patency in long term. However, the quality of RA in patients with DM is in bad condition, and further research on patency needs to be done.

Comparative anatomical description of forearm and hand arteries of cebus libidinosus / Descripción anatómica comparativa de las arterias del antebrazo y de la mano del cebus libidinosus

Recent data justify the insertion of Cebus on behavioral and evolutionary studies in relation to the human specie, reason why researches on behavior, memory, use of tools and encephalic index demonstrate that Cebus and chimpanzees are similar. Comparative anatomical studies between Cebus and chimpanzees based on anatomical data corroborate these data on evolutionary convergence associated to muscles, nerves and vessels of the thoracic members; however, the anatomy of the forearm and hand vessels has not yet been investigated in last years. The forearm and hand arteries of Cebus are identical to other here studied primates; however, the paknaris arch, which is only one in Cebus and baboons, and princeps pollicis artery, which originated from the paknaris arch, are the main differences found for the arterial model of Cebus and for other primates. The vascularization model is identical to others primates and humans, but the hand vessels are different and more similar to baboons.

Los datos recientes justifican la inserción de Cebus en los estudios sobre la evolución y el comportamiento en relación con la especie humana ya que, investigaciones sobre su comportamiento, memoria, uso de herramientas y índice encefálico han demostrado que los chimpancés y Cebus son similares en estos aspectos. Por otra parte, estudios anatómicos comparados de los Cebus y chimpancés sobre los datos anatómicos corroboran estos hechos sobre la convergencia evolutiva asociada a los músculos, nervios y vasos de los miembros torácicos, pero la anatomía de las arterias del antebrazo y mano no se ha investigado. En el antebrazo y mano de los Cebus las arterias son idénticas a otros primates estudiados aquí, pero el arco palmar es sólo uno en los Cebus y babuinos y, la arteria principal del pulgar se origina a partir del arco palmar. Éstas son las principales diferencias encontradas para el modelo arterial de Cebus y de otros primates a excepción de los babuinos. El modelo general de la vascularización del Cebus es idéntico al de otros primates y seres humanos, pero las características particulares de algunas arterias son diferentes a éstos últimos y más similares a babuinos.

Comparison of the pretreatment effects of mixed vasodilators (3-D solution) on radial and internal thoracic arteries by using a 3-dimensional anaglyph electron microscope technique.

OBJECTIVE: Currently, internal thoracic arteries (ITA) and radial arteries (RA) are the first choice of conduits for coronary artery bypass grafts (CABG). Because the perioperative vasospasm continues to be a major problem, a number of pharmacologic agents such as papaverine, calcium receptor blockers, nitroglycerine, and phenoxybenzamine have been suggested as topical antispasmodics that may be used in the pre- and postoperative periods. In the present study, we investigated the quantitative efficacies of the mixed solution, which included verapamil, nitroglycerin, and papaverine, on RA and ITA using a scanning electron microscope with a 3-dimensional anaglyph technique. METHODS: Diameter changes of RA and ITA in response to clinically important vasodilators were measured on 40 RA and 40 ITA rings from patients who had been subjected to coronary artery bypass procedure after 20 minutes of ex vivo incubation with verapamil (45 microg/L), nitroglycerin (45 microg/L), papaverine solution (266 micromol/L or 0.1 micro/mL), and 30 mL autologous heparinized whole blood (individual patient's blood obtained before cardiopulmonary bypass contained 100 IU of heparin per kg of patient weight). The pretreatment action was assessed by measuring the response to vasodilators. RESULTS: In all cases, we did not observe graft vasospasm in any of the conduits during the intraoperative period between postanastomosis and sternal closure. In the postoperative period, we did not record any evidence of ischemic change in patients' electrocardiographic and myocardial enzyme analyses. None of the cases required inotropic support after the operation. The diameters of the pretreated RA and ITA were: minimum, 2.1 mm; maximum, 4.0 mm; and mean value, 2.80 +/- 0.46 mm. The diameters of the pretreated ITA were: minimum, 1.2 mm; maximum, 2.5 mm; and mean value, 1.76 +/- 0.35 mm. Incubated arterial segment diameters for the RA were: minimum, 2.8 mm; maximum, 5.2 mm; and mean value, 3.95 +/- 0.65 mm. These values for the ITA were: minimum, 1.5 mm; maximum, 3.9 mm; and mean value, 2.37 +/- 0.50 mm. These findings were statistically significant for both arterial grafts (P <.05). CONCLUSIONS: According to our study findings, the mixed solution demonstrates a broad range of efficacy. We conclude that the described vasodilator solution with heparinized autologous blood seems to be very effective and may be used as a pretreatment agent in CABG conduits. Although papaverine has the shortest duration of action, its efficiency is increased by verapamil and nitroglycerin, in our opinion. To the best of our knowledge, high-quality imaging of CABG conduits with the 3-D anaglyph technique using a scanning electron microscope was a first in the literature. This technical approach may be used for confirming the ultrastructural anatomy and the quantitative vasodilator effects of arterial conduits. We believe that valuable anatomo-pathologic details of the CABG conduit can be obtained by this technique.

The choice of the technique for harvesting and preparation of the radial artery for coronary artery bypass grafting.

At present coronary artery disease (CAD) is a most frequently occurring cause of the lethality and disability of patients. One of the basic methods for CAD treatment is coronary artery bypass grafting (CABG). Actuality of the problem of applying the radial artery (RA) for CABG is determined by the proven advantage of arterial grafts versus vein grafts in myocardial revascularization. Today the RA ranks second in frequency of using the arterial graft subsequently to the internal thoracic artery (ITA). The RA may be harvested by two techniques: skeletization and in a case with surrounding tissue. However, to this day there is no unanimous opinion as regards the advantages of one or another approach. Of importance is conduit conservation from the time of harvesting to implantation into the coronary artery position. Despite a great number of conservants offered for conservation before implantation, comparative analysis of their effect on the conduit endothelium was not carried out. The problem of the safety of the RA conduit also remains open to discussion.

[Comparative study on the ultrastructures of radial and internal mammary arteries used for coronary artery bypass grafting].

OBJECTIVE: The radial artery differs from internal mammary artery in its vascular biology and long-term patency after coronary artery bypass grafting (CABG). This study was designed to investigate their ultrastructural differences that may have implications in arterial remodeling and graft failure. METHODS: Thirty-four radial artery and 11 internal mammary artery samples were obtained from patients underwent CABG, and subjected to routine electron microscopic examination. A semi-quantitative method was used to evaluate secretary endothelial cells, endothelial denudation, synthetic smooth muscle cells (SMCs), matrix accumulation, lipid deposition and medial submicroscopic calcification. RESULTS: Compared with internal mammary arteries, the radial arteries had more secretory endothelial cells (47.1%, 16/34 vs 27.2%, 3/ 11) and synthetic type SMCs in a background (14.4% vs 0.9%) that had more intimal lipid deposition and matrix accumulation (14.7%, 5/34 vs 9.1%, 1/11). Matrix vesicles and calcifications were frequently present in the media of both types of arteries. The calcifications, however, could not be visualized by routine histological stains, and therefore, named as submicroscopic calcification in this study. Fewer endothelial denudations were observed in the radial arteries, but no differences in medial lipid deposition and submicroscopic calcification were observed between these two types of arteries. The ultrastructural features and the arrangement of medial SMCs in radial arteries were similar to those of internal mammary arteries. CONCLUSIONS: Radial arteries have a higher SMC proliferative potential and more actively secretory status of endothelial cells, which may enhance the remodeling process and correlate with a decreased long-term patency. Better preservation of endothelial cells in radial arteries could be attributed to the "no touch" technique utilized in surgical harvesting. The significance of submicroscopic medial calcification during graft remodeling requires further investigations.

Implantation in coronary circulation induces morphofunctional transformation of radial grafts from muscular to elastomuscular.

BACKGROUND: The purpose of this research was to investigate the in vivo morphofunctional changes induced in the radial artery (RA) by its use as coronary artery bypass conduit by comparing the morphological features and vasoreactivity of the native RA versus the coronary RA graft in the same patient. METHODS AND RESULTS: Ten years after surgery, 10 patients were submitted to intravascular ultrasound examination of the RA graft of the controlateral (in situ) RA and of the internal thoracic artery (ITA) graft and to vasoactive challenges with acetylcholine and serotonin. Quantitative angiographic assessment showed that the mean diameter of the RA coronary grafts was significantly larger than that of the in situ RA and of the ITA (2.89+/-0.40 mm RA grafts, 2.14+/-0.52 mm in situ RA, 2.25+/-0.53 mm ITA grafts; P<0.001). The in situ RA demonstrated a typical muscular architecture, whereas RA coronary grafts showed a clear reduction of the thickness of the medial layer and had a less well-defined muscular component of the media with interposition of elastic tissue. Serotonin endovascular infusion elicited a strong spastic reaction in in situ RAs; the same challenge induced only moderate constriction in RA and ITA coronary grafts. CONCLUSIONS: Implantation in the coronary circulation leads to major anatomic and vasoreactive modifications of the RAs that tend to lose the morphofunctional features of a muscular conduit and assume those of an elastomuscular artery, such as the ITA.

Harvesting techniques affect the integrity of the radial artery: an electron microscopic evaluation.

BACKGROUND: Four methods of radial artery harvesting were evaluated with transmission electron microscopy and tissue lipid peroxidation to determine the degree of damage to the artery. METHODS: Radial artery samples from 4 groups of patients (10 samples from each group) who underwent coronary artery surgery were evaluated. In groups I and II, radial arteries were stored in a solution containing 100 mL patients' own heparinized oxygenated blood and 5 mg nitroglycerine. The grafts were distended in group II. In groups III and IV, side branches of the grafts were occluded and left in situ until the coronary anastomosis. In group III, the distal end of the graft was also occluded, while in group IV, both ends were open. RESULTS: The least degree of endothelial damage and disruption of arterial wall integrity were in group IV according to electron microscopic evaluation. The grafts in group III were relatively in good condition compared to groups I and II. Tissue lipid peroxidation was also lowest in group IV. Tissue lipid peroxide levels correlated with ischemic preservation period of the radial artery (r = 0.426). Total semiquantitative transmission electron microscopic scores of the radial artery samples correlated with the lipid peroxide levels (r = 0.581) and ischemia times (r = 0.734). CONCLUSIONS: All arterial grafts, including the radial artery that will be used for coronary artery surgery should not be left ischemic during harvesting to prevent endothelial damage. Ischemia of the conduits for coronary artery grafting can be prevented by leaving them in their anatomic position until the distal coronary artery anastomosis.

Arterial endothelial denudation by intraluminal use of papaverine-NaCl solution in coronary bypass surgery.

OBJECTIVES: Preservation of endothelial integrity during coronary artery bypass grafting is considered important for short- and long-term patency of the graft. In current literature there are controversial data about the safety of papaverine, a vasorelaxant widely used in coronary artery bypass grafting. Accordingly, we examined the immediate effects of papaverine on the endothelial morphology of arterial grafts and on viability of cultured human coronary artery endothelial cells. METHODS: Totally 22 segments of the radial artery were collected from 11 patients undergoing coronary artery bypass grafting. The segments were cut from the distal redundant parts of the arteries, which were not required for bypass grafting. A small distal segment of the artery was excised and placed into autologous heparinized whole blood (control segment). The rest of the graft, still remaining proximally attached to the circulation, was treated intraluminally with papaverine-NaCl solution (pH 4.2) for 5 min, after which another small distal segment was excised for the study (papaverine-treated segment). Segments were then perfusion-fixed and the endothelial surface was examined by scanning electron microscopy. Endothelial denudation was assessed and its severity graded. Additionally, viability of cultured human coronary artery endothelial cells after treatment with papaverine was assessed with trypan blue staining. RESULTS: Treatment with papaverine solution markedly increased the endothelial denudation (grades from 6.2+/-1.7 to 10.0+/-3.5; mean+/-SD; P=0.004). Papaverine-treatment increased trypan blue staining of cultured human coronary artery endothelial cells regardless of papaverine diluent (normal saline of pH 4.5 or 7.4 or blood). CONCLUSIONS: Treatment of arterial grafts with papaverine solutions apparently damages endothelial cells. Thus, the clinical practice of dilating arterial bypass grafts with papaverine should be reassessed, and alternative methods of vasodilatation should be considered.

Skeletonization versus pedicle preparation of the radial artery with and without the ultrasonic scalpel.

BACKGROUND: The radial artery (RA) is increasingly used for myocardial revascularization because of its presumed advantageous long-term patency rates. The vessel can be harvested as a pedicle or skeletonized. The aim of this study was to compare the skeletonization technique with pedicle preparation using either an ultrasonic scalpel or scissors. METHODS: Forty consecutive patients with coronary artery disease undergoing complete arterial revascularization were included in the study. In 20 patients the RAs were prepared using scissors and clips (group 1: skeletonization; group 2: pedicle). In another 20 patients the arteries harvested were prepared using an ultrasonic scalpel (group 3: skeletonization; group 4: pedicle). The RA was treated with papaverine to prevent spasm of the vessel during and after harvesting. Tissue specimens of each RA were taken to analyze endothelial morphology by scanning electron microscopy. After implantation of the RA, graft perfusion was measured with a flow probe. RESULTS: Harvesting the RA as a skeletonized vessel took more time as compared with pedicle preparation (group 1 vs group 2: 37.1 +/- 3.5 minutes vs 24.4 +/- 3.9 minutes; p < 0.001 and group 3 vs group 4: 31.1 +/- 3.5 minutes vs 25.6 +/- 3.7 minutes; p < 0.01). The number of hemostatic titanium clips was similarly higher in group 1 as opposed to group 2 (58.7 +/- 7.1 vs 38.7 +/- 7.1; p < 0.01). However, there was no difference between groups 3 and 4 (p = 0.086). The length of the RA after skeletonization with scissors and clips was 20.8 +/- 1.5 cm in contrast with 19.1 +/- 0.9 cm (p < 0.01) after dissection as a pedicle. In the groups using the ultrasonic scalpel, there was no difference in graft length (p = 0.062). Mean blood flow through the graft after establishing the proximal anastomosis was similar among all groups (groups 1, 2, 3, and 4: 50 +/- 20.1 mL/min, 53.8 +/- 24.3 mL/min, 56.3 +/- 25.1 mL/min, and 51.8 +/- 23 mL/min, respectively). Scanning electron microscopy demonstrated endothelial damage in all patients in groups 1, 2, and 3 and in 7 patients of group 4. Most endothelial lesions were minor except in group 3 in which 1 of 5 endothelial lesions were severe. Statistically significant differences was found between groups 1 and 2, and 3 and 4 with respect to the degree of endothelial damage (p < 0.01). CONCLUSIONS: Skeletonization using scissors and clips is more time consuming and technically more difficult, but yield significantly longer grafts. Skeletonization with an ultrasonic scalpel did not result in additional length and was more frequently associated with severe endothelial damage. Pedicle preparation using scissors or an ultrasonic scalpel is much simpler and faster, and does not jeopardize endothelial integrity.

Artéria radial na ampliaçäo do uso de enxertos arteriais para revascularizaçäo do miocárdio: consideraçöes anatômicas e tática cirúrgica / Radial artery for wider utilization of arterial grafts for myocardial revascularization: anatomic considerations and surgical technique

A artéria radial (AR) foi estudada sob o ponto de vista anatômico, histológico, imunohistoquímico e ultramicroscópico. Paralelamente, foram analisados os resultados de seu emprego na revascularizaçao do miocárdio de 269 pacientes. No total, 319 artérias coronárias foram revascularizadas pela AR. Houve predomínio do sexo masculino (80,7 por cento) e da raça branca (93,7 por cento). A artéria torácica interna esquerda (ATIe) foi empregada em 246 pacientes. Outros 17 já haviam sido previamente revascularizados com a ATIe, perfazendo um total de 97,8 por cento. A artéria torácica interna direita (ATId) foi empregada em 59 (21,9 por cento) pacientes, a artéria gastroepiplóica direita (AGEd) em 17 (6,3 por cento) pacientes e em 161 (59,8 por cento) foram também realizadas l a 4 pontes de veia safena. A média de enxertos por paciente foi de 3,4. Nao houve complicaçoes isquêmicas ou infecciosas no membro em que a AR foi retirada. Os estudos imuno-histoquímicos e ultramicroscópicos permitiram observar o grande espessamente da membrana limitante elástica interna da AR e o predomínio de fibras colágenas sobre as elásticas na camada média. As principais complicaçoes pós-operatórias foram a fibrilaçao atrial em 21 (7,8 por cento) pacientes, insuficiência respiratória em 21 (7,8 por cento), alteraçoes no ECG e/ou elevaçao de CKMB em 12 (4,5 por cento) pacientes. O balao intra-aórtico foi utilizado em 6 (2,2 por cento) pacientes. O cateterismo no pós-operatório precoce foi realizado em 21 pacientes. Em l paciente houve dissecçao sem oclusao do óstio da AR pelo cateter, l (4,7 por cento) apresentou sinais de espasmo da AR; nos demais a AR encontrava-se pérvia e sem lesoes. Houve 6 (2,2 por cento) óbitos hospitalares, sendo 3 por acidente vascular cerebral, 2 por baixo débito cardíaco e l paciente teve morte súbita. Nos últimos meses temos visado à revascularizaçao miocárdica com o emprego máximo de enxertos arteriais. Como tática especial usamos a AR para anastomoses seqüenciais com as artérias de parede inferior e lateral do ventrículo esquerdo. A anastomose do coto proximal é realizada na ATIe que, por sua vez, é habitualmente anastomosada ao ramo interventricular anterior (RIA). As artérias AGEd e ATId in situ ou, como enxerto livre, têm complementado o procedimento. Dentre 64 pacientes operados nos últimos 3 meses com a utilizaçao da AR, 62 (96,9 por cento) receberam pelo menos 2 enxertos arteriais, 27 (42,2 por cento) receberam pelo menos 3 enxertos arteriais e 8 (l2,5 por cento) pacientes receberam 4 ou 5 enxertos arteriais. Em 29 (45,3 por cento) deles a AR foi anastomosada à ATIe ou ATId. Acreditamos que essa técnica reduza a excessiva pressao conseqüente à anastomose direta da AR na aorta e que o maior fluxo decorrente das anastomoses seqüenciais auxilie na manutençao da perviabilidade da AR...