Skeletonized bilateral internal mammary arteries for total arterial myocardial revascularization

BACKGROUND: Bilateral internal mammary artery (IMA) grafting is associated with an improved long-term survival, low rates of recurrence of angina and late myocardial infarction. However, because of the inadequate length of the conduit, use of bilateral internal thoracic artery grafting occasionally is not suitable for complete revascularization. To overcome this limitation, extra length can be obtained by skeletonization of both IMAs. We decided to prospectively assess the safety of this technique. METHODS: One hundred patients with a mean age of 52.5 +/- 13.1 years underwent complete revascularization with skeletonized bilateral internal mammary arteries on cardiopulmonary bypass (CPB). The right internal mammary artery (RIMA) was used as a free graft connected to the in situ left IMA (LIMA) in 88 patients. A free LIMA was attached to in situ RIMA in 12 patients. The average number of grafts was 3.2 per patient (range: 2-4 grafts per patient). Mean left ventricular ejection fraction was 60% (range: 25-80%). RESULTS: No patient required reexploration for bleeding, and no patient died within 30 days after operation. On the basis of electrocardiographic changes, three patients sustained a perioperative myocardial infarction. One patient had a sternal wound infection. Mean follow-up was 24 months (range: 6-36 months). The actuarial survival rate was 99 +/- 1% at 3 years. No myocardial infarctions were reported during the follow-up. Three patients had recurrent angina with conduit occlusion diagnosed on coronary angiography. CONCLUSION: Complete myocardial revascularization with skeletonized bilateral internal mammary arteries is a safe and reliable technique with excellent early and mid-term results.     

Attenuation by melatonin of human umbilical arterial vasoconstriction induced by lysophosphatidylcholine

We evaluated the antioxidant property of melatonin as related to the vasospastic effect of lysophosphatidylcholine (LPC), a component of oxidized lipoprotein, on the human umbilical artery. Helical sections of umbilical arteries were obtained from healthy pregnant women who were delivered between 37 and 39 wk of gestation. Changes in maximal tension induced by KCl were measured in arterial sections having intact endothelium. Sections were treated with LPC alone (15 or 30 microM), or were pretreated either with a hydrogen peroxide (H2O2) scavenger (catalase, 1,200 U/mL), a hydroxyl radical scavenger (mannitol, 30 mM), a nitric oxide (NO) synthesis inhibitor (L-N(G)-monomethyl arginine, LNMA, 2 x 10(-4) M) or melatonin (1 or 10 microM). The effect of LPC (30 microM) on the vasorelaxation induced by 5-hydroxytryptamine (5-HT) was also determined, with or without melatonin pretreatment (10 microM). LPC potentiated vascular tension in a concentration-dependent manner. Pretreatment with LNMA significantly suppressed this vasospastic effect of LPC. Pretreatment with catalase or mannitol significantly reduced the vasospastic effect of LPC. Melatonin significantly lessened the vasospastic effect of LPC in a concentration-dependent manner. Pretreatment with LPC significantly inhibited the relaxation induced by 5-HT. Treatment with melatonin prior to LPC exposure significantly restored the relaxation induced by 5-HT. Results suggest that LPC potentiates vascular tension in human umbilical artery, perhaps by suppressing the endothelial synthesis of NO. Melatonin significantly suppressed the vasospastic effect of LPC. This agent probably scavenges the hydroxyl radicals arising from LPC.     

Percutaneous transluminal angioplasty of internal mammary arteries in patients with rest angina

Angioplasty of the internal mammary artery (IMA) bypass graft has been shown to be a safe and effective revascularization procedure. However, angiographic and long term clinical outcomes in the high-risk group of patients presenting with rest angina has not been well documented. We report the results of IMA angioplasty in 20 patients with rest angina out of 614 (3.2%) who received a left IMA graft at our institution between April 1987 and September 1994. All patients were admitted with rest angina, 12 patients demonstrated persistent ischemia despite medical therapy, two patients were in heart failure, and one patient was in cardiogenic shock. Balloon angioplasty was successful in 15 of 20 patients (75%). Failed angioplasty was associated with either severe IMA tortuousity (three patients) or inability to cross the anastomotic stenosis with the guide wire (two patients). Each of these five patients required angioplasty of either the native left anterior descending artery or other saphenous vein grafts for clinical stabilization. No patient suffered a major complication (myocardial infarction, emergent coronary bypass surgery, death). Clinical follow-up was obtained in all 20 patients (6 months, 7 years, mean 27 months). Twelve patients (60%) were asymptomatic or had stable angina at follow-up, and 8 returned with anginal symptoms. Four patients required repeat angioplasty for disease in other vessels, two were treated medically for angina, one underwent repeat CABG, and cardiac transplantation was performed in one patient for refractory heart failure. Angiographic follow up was obtained in 10/15 (66%) successful angioplasty patients, and only one patient demonstrated restenosis at the treated site (10%). During follow up one patient developed an IMA stenosis at a previous dissection site in the body of the graft that was treated with angioplasty. These results suggest that IMA angioplasty in patients with rest angina is associated with excellent long term patency and clinical efficacy, as well as low procedural risk. © 1996 Wiley-Liss, Inc.     

Off-pump coronary artery bypass grafting using a bilateral internal mammary artery Y graft

Objectives To evaluate the outcome of off-pump coronary artery bypass grafting (OPCABG) using a bilateral internal mammary artery (BIMA) Y configuration graft to achieve total arterial myocardial revascularization. Methods From October 2002 to December 2008, 208 patients (196 males and 12 females) underwent OPCABG using a BIMA Y configuration graft. The average age of the patients was 56.5 ± 11.3 years, with an age range of 33–78 years. A total of 167 (80.2%) cases had triple-vessel disease. Left main stem disease was found in 33 (15.9%) cases, and double-vessel disease was found in 8 (3.9%) cases. The semi-skeletonization technique was used to harvest the two internal mammary arteries (IMAs), and then the free right internal mammary artery was connected end-to-side to the left internal mammary artery (LIMA) in situ to complete the Y configuration graft. Off-pump and sequential anastomosis methods were used to perform coronary artery bypass surgery in all patients. Graft patency was assessed intra-operatively with the HT311 transit time flowmeter. Results A total of 728 distal anastomoses were performed in 208 patients, with the average being 3.5 ± 1.3 per person. No one died or experienced recurrent angina within 30 days after the operation. Conclusions OPCABG using the BIMA Y graft was safe and effective to achieve total arterial revascularization. This method avoids surgical operation on the ascending aorta and other incisions.     

Melatonin inhibits vasospastic action of oxidized low-density lipoprotein in human umbilical arteries

We evaluated the antioxidant property of melatonin in countering the vasospastic effect of oxidized low-density lipoprotein (ox-LDL), which has been reported to be the most important risk factor for atherosclerosis and also may be linked to preeclampsia. Helical sections of umbilical arteries were obtained from human placentas at elective cesarean deliveries between 37 and 39 weeks of gestation. Changes in maximal tension induced by potassium chloride were measured in arterial sections with intact endothelium. ox-LDL (200 or 300 microg protein/mL) increased vascular tension by 15.6 +/- 2.3 or 31.9 +/- 4.0%, respectively. In contrast, native LDL only slightly increased vascular tension (2.7 +/- 1.0% for 200 microg protein/mL and 6.0 +/- 1.7% for 300 microg protein/mL). Pretreatment with L-N(G)-monomethyl-arginine (2 x 10(-4) M) significantly reduced the vasospastic effect of ox-LDL, as did pretreatment with mannitol (30 mM). Melatonin (10 microM) significantly reduced the vasospastic effect of ox-LDL. These findings suggest that ox-LDL potentiates vascular tension in the human umbilical artery, possibly by suppressing endothelial synthesis of nitric oxide. Melatonin significantly suppressed the vasospastic effect of ox-LDL, probably because it scavenges hydroxyl radical arising from ox-LDL.     

Vasorelaxant properties of isolated human radial arteries: comparison with internal mammary arteries

Radial arteries, used in revascularisation surgery, are prone to spasm. We have examined the ability of nitrovasodilators, calcium channel blockers, and K_ATP channel openers to cause vasodilation, and to attenuate contractions due to depolarisation and receptor activation in radial and mammary arteries used in coronary artery bypass graft surgery. Two to three millimetre rings of artery obtained from patients at surgery were studied in organ baths in vitro. Constriction to KC1 and phenylephrine was examined before and again after treatment of the rings with drug or vehicle. Calcium channel blockers were the only compounds to inhibit contractions to both KC1 and phenylephrine. Sodium nitroprusside attenuated constriction to phenylephrine but not KC1 in both vessels. K_ATP channel openers similarly attenuated constriction to phenylephrine in radial arteries but were much less effective in mammary arteries. These studies support the continued use of calcium blockers after revascularisation with radial artery but suggest that other classes of drug may be as effective at minimising spasm due to receptor mediated constriction.     

Nitrosation of melatonin by nitric oxide: a computational study

Melatonin is being increasingly promoted as a therapeutic agent for the treatment of jet lag and insomnia, and is an efficient free radical scavenger. We have recently characterized a product for the reaction of melatonin with nitric oxide (NO), N-nitrosomelatonin. In the present work, reaction pathways with N1, C2, C4, C6 and C7 as possible targets for its reaction with NO that yield the respective nitroso derivatives have been investigated using semiempirical AM1 computational tools, both in vacuo and aqueous solution. Specifically, two different pathways were studied: a radical mechanism involving the hydrogen atom abstraction to yield a neutral radical followed by NO addition, and an ionic mechanism involving addition of nitrosonium ion to the indolic moiety. Our results show that the indolic nitrogen is the most probable site for nitrosation by the radical mechanism, whereas different targets are probable considering the ionic pathway. These results are in good agreement with previous experimental findings and provide a coherent picture for the interaction of melatonin with NO.     

Protective effect of melatonin in a model of traumatic brain injury in mice

ABSTRACT: The pineal hormone melatonin has recently been shown to exert neuroprotective activity in a variety of experimental neuropathologies in which free radicals are involved. This neuroprotective effect has been attributed to the antioxidant properties of melatonin. Considering that free radicals also play a deleterious role in traumatic brain injury (TBI), the purpose of the present study was to determine whether melatonin would have a beneficial effect in this pathology. Head injury was induced in mice and the neurological deficit was evaluated at 24 hr by a grip test. In this model, the free radical scavenger, α-phenyl-tert-butyl-nitrone (2 ± 100 mg/ kg, i.p.) given 5 min and repeated at 4 hr after TBI was neuroprotective. Melatonin (1.25 mg/kg, i.p.) given 5 min and repeated at 1,2, and 3 hr after head trauma also significantly reduced the neurological deficit. This beneficial effect was not due to melatonin-induced hypothermia since repeated treatment with melatonin did not modify the colonic temperature of mice. This study shows that melatonin exerts a beneficial effect on the neurological deficit induced by traumatic brain injury in mice. The mechanisms of this neuroprotection remains to be established, and more particularly, the contribution of the antioxidant activity of melatonin.     

Melatonin inhibits vasopastic action of hydrogen peroxide in human umbilical artery

ABSTRACT: We evaluated the antioxidant property of melatonin as it relates to the vasospastic effect of hydrogen peroxide (H₂O₂) on the human umbilical artery. Helical sections of umbilical arteries were obtained from healthy pregnant women who were delivered between weeks 37 and 39 of gestation. Changes in maximal potassium chloride (KCl)-induced tension were measured in arterial segments with intact endothelium. Segments were treated with H₂O₂ alone, or were pretreated either with an H₂O₂scavenger (catalase, 2000 IU), a hydroxyl radical scavenger (mannitol, 10^?2M), a nitric oxide-synthesis inhibitor (L-N^G-monomethyl arginine, LNMA, 2 × 10^?4M), or melatonin (10^?6M to 10^?4M). The effect of H₂O₂(10^?4M) on the relaxation induced by the calcium ionophore A23187 was also determined in arterial segments, with or without pretreatment with melatonin (10^?6M, 10^?4M). H₂O₂ (10^?6 M to 10^?4 M) potentiated vascular tension in a concentration-dependent manner (P < 0.0001). Pretreatment with LNMA significantly suppressed the vasospastic effect of H₂O₂ (P < 0.0001). Pretreatment with either catalase or mannitol significantly reduced the vasospastic effect of H₂O₂ (P < 0.005, P < 0.002, respectively). Melatonin also significantly reduced the vasospastic effect of H₂O₂ in a concentration-dependent manner (H₂O₂ 10^?6 M, P < 0.0001: H₂O₂ 10^?5 M, P<0.0001: H₂O₂ 10^?4M, P < 0.00001). Pretreatment with H₂O₂ significantly inhibited the relaxation induced by the calcium ionophore A23187 (P < 0.005). Treatment with melatonin prior to exposure to H₂O₂ significantly restored the relaxation induced by A23187 (P < 0.005). Results suggest that H₂O₂ potentiates vascular tension in the human umbilical artery, perhaps by suppressing the endothelial synthesis of nitric oxide. Melatonin significantly suppressed the vasospastic effect of H₂O₂, possibly due to its ability to scavenge the hydroxyl radical.     

Beneficial effects of melatonin on in vitro bovine embryonic development are mediated by melatonin receptor 1

In the current study, a fundamental question, that is, the mechanisms related to the beneficial effects of melatonin on mammalian embryonic development, was addressed. To examine the potential beneficial effects of melatonin on bovine embryonic development, different concentrations of melatonin (10^?11, 10^?9, 10^?7, 10^?5, 10^?3 m ) were incubated with fertilized embryos. Melatonin in the range of 10^?11 to 10^?5 m significantly promoted embryonic development both in early culture medium (CR1aa +3 mg/mL BSA) and in later culture medium (CR1aa + 6%FBS). The most effective concentrations applied in the current studies were 10^?9 and 10^?7 m . Using quantitative real‐time PCR with immunofluorescence and Western blot assays, the expression of melatonin receptor MT1 and MT2 genes was identified in bovine embryos. Further studies indicate that the beneficial effects of melatonin on bovine embryo development were mediated by the MT1 receptor. This is based on the facts that luzindole, a nonselective MT1 and MT2 antagonist, blocked the effect on melatonin‐induced embryo development, while 4‐P‐PDOT, a selective MT2 antagonist, had little effect. Mechanistic explorations uncovered that melatonin application during bovine embryonic development significantly up‐regulated the expression of antioxidative (Gpx4, SOD1, bcl‐2) and developmentally important genes (SLC2A1, DNMT1A, and DSC2) while down‐regulating expression of pro‐apoptotic genes (P53, BAX, and Caspase‐3). The results obtained from the current studies provide new information regarding the mechanisms by which melatonin promotes bovine embryonic development under both in vitro and in vivo conditions.     

Assessment of left internal mammary artery graft patency by transthoracic Doppler echocardiography

BACKGROUND: The successful application of noninvasive Doppler spectrum analysis has been reported for the hemodynamic assessment of LIMA graft after myocardial revascularization. HYPOTHESIS: The objective of this study was to assess the utility of transthoracic Doppler echocardiography (TTE) in providing information on LIMA flow in patients after coronary artery bypass graft surgery. METHODS: In all, 22 patients (aged 62 +/- 8 years) with LIMA graft to the left anterior descending (LAD) coronary artery who underwent coronary angiography were assessed using high-frequency (5 MHz) transthoracic Doppler echocardiography. They were compared with 25 patients with angina (control group A, aged 59 +/- 12 years), in whom an ungrafted LIMA was assessed, and with 17 patients (control group B, aged 59 +/- 9 years) with angiographically normal coronary arteries, in whom the LAD was assessed. RESULTS: A biphasic pattern (systolic and diastolic) was recorded in all cases. In 14 patients with a normal graft or < 70% stenosis (Group 1) and in control group B, blood flow was maximal during diastole. In eight patients with severe graft stenosis > 70% (Group 2) and control group B, blood flow was maximal during systole, with low diastolic flow. The diastolic fraction of the velocity time integrals was 0.81 +/- 0.11 for Group 1 and 0.25 +/-0.06 for Group 2 (p < 0.05). A diastolic velocity time integral fraction < 0.5 predicted > 70% stenosis with a sensitivity and specificity of 100%. The ratio of systolic/diastolic peak velocities was 0.61 +/- 0.31 for Group 1 and 3.21 +/- 0.49 for Group 2 (p < 0.05). A systolic/diastolic peak velocity > 1 predicted stenosis > 70% with a sensitivity and specificity of 100 and 90%, respectively. CONCLUSIONS: High-frequency TTE is a useful noninvasive method for detecting LIMA graft blood flow. Severe graft stenoses exhibited Doppler velocity patterns, which were different from those of patent grafts, or grafts with moderate stenoses.     

A review of metal‐catalyzed molecular damage: protection by melatonin

Metal exposure is associated with several toxic effects; herein, we review the toxicity mechanisms of cadmium, mercury, arsenic, lead, aluminum, chromium, iron, copper, nickel, cobalt, vanadium, and molybdenum as these processes relate to free radical generation. Free radicals can be generated in cells due to a wide variety of exogenous and endogenous processes, causing modifications in DNA bases, enhancing lipid peroxidation, and altering calcium and sulfhydryl homeostasis. Melatonin, an ubiquitous and pleiotropic molecule, exerts efficient protection against oxidative stress and ameliorates oxidative/nitrosative damage by a variety of mechanisms. Also, melatonin has a chelating property which may contribute in reducing metal‐induced toxicity as we postulate here. The aim of this review was to highlight the protective role of melatonin in counteracting metal‐induced free radical generation. Understanding the physicochemical insights of melatonin related to the free radical scavenging activity and the stimulation of antioxidative enzymes is of critical importance for the development of novel therapeutic strategies against the toxic action of these metals.     

Radiographic anatomy of the internal mammary arteries

The radiographic anatomy of the IMAs is described based on bilateral selective arteriography in 100 patients with coronary artery disease. The right and left IMAs were identical in caliber in their mid portions in 94% of cases. Fifteen percent of the IMAs measured less than 2 mm in luminal diameter at the level of the fourth costal cartilage. The side branches showed a great deal of variability and asymmetry in their origin and distribution. The understanding of the radiographic anatomy of the IMA and its branches is helpful in preoperative appraisal and is crucial for postoperative evaluation of the IMA grafts.     

Protective effect of melatonin against oxidative stress induced by ligature of extra-hepatic biliary duct in rats: comparison with the effect of S-adenosyl-L-methionine

In the present research, we studied the effect of the administration of melatonin or S-adenosyl-L-methionine (S-AMe) on oxidative stress and hepatic cholestasis produced by double ligature of the extra-hepatic biliary duct (LBD) in adult male Wistar rats. Hepatic oxidative stress was evaluated by the changes in the amount of lipid peroxides and by the reduced glutathione content (GSH) in lysates of erythrocytes and homogenates of hepatic tissue. The severity of the cholestasis and hepatic injury were determined by the changes in the plasma enzyme activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (AP), g-glutamyl-transpeptidase (GGT), and levels of albumin, total bilirubin (TB) and direct bilirubin (DB). Either melatonin or S-AMe were administered daily 3 days before LBD, and for 10 days after biliary obstruction. LDB caused highly significant increases in plasma enzyme activities and in bilirubin and lipid peroxides levels in erythrocytes and hepatic tissue. At the same time, this procedure produced a notable decrease in the GSH pools in these biological media. Both melatonin and S-AMe administration were effective as antioxidants and hepatoprotective substances, although the protective effects of melatonin were superior; it prevented the GSH decrease and reduced significantly the increases in enzyme activities and lipid peroxidation products produced by biliary ligature. S-AMe did not modify the increased GGT activity nor did it decrease greatly the TB levels (43% melatonin vs. 14% S-AMe). However, S-AMe was effective in preventing the loss of GSH in erythrocytes and hepatic tissue, as was melatonin. The obtained data permit the following conclusions. First, the LDB models cause marked hepatic oxidative stress. Second, the participation of free radicals of oxygen in the pathogenecity and severity of cholestasis produced by the acute obstruction of the extra-hepatic biliary duct is likely. Third, the results confirm the function of S-AMe as an antioxidant and hepatoprotector. Finally, melatonin is far more potent and provides superior protection as compared to S-AMe. Considering the decrease in oxidative stress and the intensity of cholestasis, these findings have interesting clinical implications for melatonin as a possible therapeutic agent in biliary cholestasis and parenchymatous liver injury.     

Antioxidative effects of melatonin in Drosophila melanogaster: Antagonization of damage induced by the inhibition of catalase

In Drosophila melanogaster strain Canton S, the catalase inhibitor 3-amino-1,2,4-triazole was used to enhance oxidative stress from endogenous sources. This treatment was chosen as an alternative to direct administration of oxidants, which would cause damage and interact with melatonin already in the extracellular space before they reach the intracellular compartments. Male flies were kept in constant darkness and fed 1% sucrose as the only diet, with or without additions of melatonin (2 mM), inhibitor (100 mM), or combinations of both. After 20 or 24 hr, most of the animals exposed to 3-amino-1,2,4-triazole only had died, whereas a large number of flies had survived the inhibitor treatment in the presence of melatonin. Protein carbonyl, an indicator of oxidative protein modification, and lipid peroxidation, as determined by the formation of malondialdehyde and 4-hydroxyalkenal, were measured in flies treated for 20 hr. Melatonin alone did not substantially change these parameters, but prevented the increase in protein carbonyl caused by the catalase inhibitor. The effect of 3-amino-1,2,4-triazole on lipid peroxidation was relatively minor, but a clear-cut inhibition was found after simultaneous administration of melatonin. The preferential suppression of oxidative damage of proteins, as compared to lipids, indicates a particular protective role for melatonin in the aqueous phase of cellular compartments.     

Oxidative stress of the newborn in the pre- and postnatal period and the clinical utility of melatonin

Abstract:  Newborns, and especially those delivered preterm, are probably more prone to oxidative stress than individuals later in life. Also during pregnancy, increased oxygen demand augments the rate of production of reactive oxygen species (ROS) and women, even with normal pregnancies, experience elevated oxidative stress and lipid peroxidation compared with nonpregnant women. Also, there appears to be an increase in ROS generation in the placenta of pre-eclamptic women. In comparison with healthy adults, newborn infants have lower levels of plasma antioxidants such as vitamin E, β-carotene, and sulphydryl groups, lower levels of plasma metal binding proteins including ceruloplasmin and transferrin, and reduced activity of erythrocyte superoxide dismutase. This review summarizes conditions of newborns where there is elevated oxidative stress. Included in this group of conditions is asphyxia, respiratory distress syndrome and sepsis and the review also summarizes the literature related to clinical trials of antioxidant therapies and of melatonin, a highly effective antioxidant and free radical scavenger. The authors document there is general agreement that short-term melatonin therapy may be highly effective and that it has a remarkably benign safety profile, even when neonates are treated with pharmacological doses. Significant complications with long-term melatonin therapy in children and adults also have not been reported. None of the animal studies of maternal melatonin treatment or in postnatal life have shown any treatment-related side effects. The authors conclude that treatment with melatonin might result in a wide range of health benefits, improved quality of life and reduced healthcare costs and may help reduce complications in the neonatal period.     

二维多普勒评价药物对旁路移植术后和原位乳内动脉血流的作用

目的比较硝酸甘油及硝苯地平对原位右乳内动脉(rightinternalmammaryartery,RIMA)及冠状动脉旁路移植术后的左乳内动脉(leftinternalmammaryartery,LIMA)血流特性的影响,为冠状动脉旁路移植术后用药提供药理学的依据。方法对11例冠状动脉旁路移植术患者术后1周在胸骨旁左右第1肋间用4.5mHz和3.7mHz的多普勒传感器测定RIMA与LIMA的直径、时间流速积分和心输出量,并分别求出血流量、全身循环阻力及局部血管阻力,观察这些指标在舌下含服硝酸甘油及硝苯地平前后的变化。结果舌下含服硝酸甘油及硝苯地平能引起平均动脉压及全身循环阻力不同程度的下降(P<0.05),两药间的数值差异无统计学意义(P>0.05)。用硝苯地平后心输出量在增加,差异有统计学意义(P<0.05);用硝酸甘油后有增加,但差异无统计学意义(P>0.05)。用硝酸甘油后RIMA的直径增加,差异有统计学意义(P<0.05),而血流量及局部血管阻力无明显变化;用硝苯地平后RIMA的直径及血流量均明显增加,局部血管阻力下降,差异有统计学意义(P<0.05),且用硝苯地平后RIMA的血流量较用硝酸甘油后增加更明显,差异有统计学意义(P<0.05),相对应局部血管阻力下降更加明显,差异有统计学意义(P<0.05)。LIMA的直径及血流量在用硝酸甘油和硝苯地平后均明显增加,而用硝苯地平后增加更加显著,差异有统计学意义(P<0.05),局部血管阻力在用硝酸甘油和硝苯地平后明显下降,以硝苯地平为更显著,差异有统计学意义(P<0.05)。结论①硝酸甘油和硝苯地平对冠状动脉旁路移植术后的LIMA的作用是增加直径及血流量,减低局部血管阻力,而以硝苯地平作用更强;②原位RIMA只受硝苯地平的影响,说明硝苯地平扩血管作用更强;③两药增加血流量是通过扩张血管而不是增加时间流速积分发挥作用的。     

Elective stenting of a de novo ostial lesion of the right internal mammary artery

Elective stenting for severe stenosis involving the origin of a right internal mammary artery graft was performed in a 60-year-old patient with severe unstable angina 2 yr after surgical revascularization. The procedure had an excellent immediate result which persisted at 6-mo angiographic follow-up. This unusual localization of arterial narrowing will probably be increasingly recognized as the right internal mammary artery becomes a first-choice conduit for right coronary artery bypass. Cathet. Cardiovasc. Diagn. 44:325–327, 1998. © 1998 Wiley-Liss, Inc.     

Traumatic ostial stenosis of internal mammary coronary graft

Because of the extensive use of arterial conduits for coronary surgery there is a growing interest in percutaneous intervention in these conduits. This kind of intervention presents a challenge for the interventional cardiologist owing to the anatomic and functional characteristics of this graft. In most cases significant internal mammary artery disease occurs at the distal anastomosis. Ostial stenoses are rare and their pathology uncertain. The authors report a case of an ostial graft lesion, most probably caused by repetitive ostial engagement of the left internal mammary artery in combination with atherosclerosis in the subclavian artery affecting the internal mammary artery. (Int J Cardiovasc Intervent 2004; 1: 43–44)