The use of the internal mammary artery for myocardial revascularisation in patients 70 years of age and older. Does it complicate the early post-operative period?

In the last years common agreement has been reached that the internal mammary artery (IMA) is the conduit of choice for elective myocardial revasculariation. This trend has been stimulated by the long-term patency of the IMA grafts and the better long-term survival. However, with the increase in life-expectancy, an increasing number of elderly patients is referred for coronary artery bypass grafting. In this patient population the long-term survival is generally limited, and therefore many surgeons do not use the IMA as graft. However, there is not only the better long-term survival but also a reduction in recurrence of angina, cardiac events, and need for reoperations associated with the IMA use. In this study the perioperative (peroperative and early postoperative) mortality and morbidity of coronary artery surgery with IMA use and without IMA use in patients aged 70 years and older is compared. Based on the early clinical results it is suggested that the use of an IMA graft does not influence the perioperative morbidity and mortality of coronary artery surgery in the patient over 70, who thus should not be denied the conduit of choice on such grounds.     

Expanded use of the right and left internal mammary arteries for myocardial revascularization

While the use of the left internal mammary artery (IMA) has become routine in many cardiac surgery units there is some reluctance to utilize the right IMA. The reasons for this are the higher morbidity and mortality observed in the initial experience with bilateral IMA grafting, the limited length of the right IMA, and its potential injury in reoperations when used to revascularize the left anterior descending artery. In this series of 50 patients the right IMA was used as a conduit for myocardial revascularization. One hundred and fifty-nine coronary vessels were grafted (3.2 per patient) 67.3% with IMA and only 32.7% with vein grafts. The right IMA was used for 51 anastomoses and the left for 56, either as simple, sequential or Y type grafts. The refinement of techniques for constructing the IMA grafts used in this series show that the right IMA can reach in most of the cases the anastomotic sites of the right coronary artery beyond the acute margin of the heart, and it is hoped that the lateral positioning of the IMA pedicles will lessen the chance of graft injury at reoperation. On the basis of early clinical results (2% mortality and 4% sternal complications), the application of the right IMA seems justified electively for the revascularization of both left and right coronary artery systems or as a free graft in conjunction with the left IMA.     

Contractile properties of coronary artery bypass conduit--comparison between saphenous vein and internal mammary artery

This study was designed to examine the response of coronary artery bypass conduit to serotonin, phenylephrine, and ergonovine as provocation agents of vasoconstriction. Saphenous veins (SV) and internal mammary arteries (IMA) were obtained during coronary artery bypass grafting (CABG), and their contractile properties were measured using isometric contraction recording apparatus. Both SV and IMA showed sigmoid contraction curves indicating dose dependence to ergonovine, serotonin, and phenylephrine. The concentration-response relations for phenylephrine showed a similar curve in both SV and IMA, however, those for ergonovine and serotonin showed a leftward shift in SV compared with IMA. Half maximum effective dose for ergonovine and serotonin were less in SV than IMA. From these results, it was suggested that "perioperative spasm" during CABG might occur not only in coronary arteries but also in the graft conduit itself. Graft spasm might be a possible mechanism for occlusion of the bypass graft. In conclusion, greater hyperreactivity of SV compared with IMA in response to ergonovine and serotonin was suggested, so it is concluded that, from this point of view, IMA is more suitable for use in CABG.     

Short- and medium-term study of arterial grafts and native coronary circulation after in situ implant of the internal mammary artery

The internal mammary artery (IMA) is being increasingly utilized as a conduit for myocardial revascularization, based on its higher long-term patency. The aim of this study is the serial assessment of the changes of native coronary vessels after IMA coronary anastomosis. Twenty-six consecutive patients (24 males and 2 females, mean age 56.4 years) received an IMA graft on the left anterior descending (LAD) artery. IMA coronary anastomosis was single in 11 patients and double (LAD and diagonal branch) in the remaining 15 cases. In 23 patients (88.5%) at least one associated saphenous vein graft was inserted. Post-operatively, no new Q waves or low-output syndromes were observed. Follow-up angiographic study, including selective opacification of the IMA graft, was carried out after 1 month and after 1 year. The cumulative patency rate of IMA grafts was 97.7% after 1 month. The LAD stenosis proximal to the IMA anastomosis progressed to total occlusion in 6 patients (28.5%), all of them with a preoperative stenosis ranging from 90 to 99%; its diameter remained unchanged in 6 patients (28.5%), while a reduction of the coronary narrowing greater than or equal to 20% was observed in 9 patients (43%). Preoperatively, the LAD stenosis of the latter groups ranged from 70 to 90%. Severity of residual stenosis and relative diameters of LAD artery and IMA graft influenced the competitive flow distribution through these vessels.(ABSTRACT TRUNCATED AT 250 WORDS)     

Internal mammary coronary artery bypass surgery: experience with 1000 cases

A study of 813 men and 187 women who underwent internal mammary artery (IMA) bypass from 1976 to the present time is presented. In approximately 10% of patients, only the IMA was used for coronary artery bypass, and in approximately 90%, one to four saphenous vein grafts were used additionally. Hospital mortality in the series was 1.8%. The IMA, when properly selected and carefully harvested, is considered an excellent conduit for myocardial revascularization. Disadvantages include its limited application to the proximal portions of one (or two) coronary vessels, a relatively delicate and difficult anastomosis, and an allegedly high incidence of postoperative chest wall discomfort with pulmonary complications. However, this experience with IMA coronary artery bypass supports the view that it is an ideal conduit for the anterior wall when conditions permit its use.     

Subclavian coronary steal syndrome: an obligatory common fate between subclavian artery,internal mammary graft and coronary circulation

The long-term patency of the left internal mammary artery (IMA) has made it the preferred conduit for myocardial revascularization. The proximal segment of the subclavian artery becomes functionally connected to the coronary circulation as a result of IMA implantation during coronary artery bypass surgery. The subclavian coronary steal syndrome results from stenosis in the left subclavian artery proximal to the IMA, compromising blood flow to the myocardium. We describe 7 patients, aged 55-75 years, 1.7-10.5 years after coronary bypass who presented with recurrent angina due to subclavian artery stenosis. The IMA graft was found open in each patient. A true steal mechanism was not demonstrated, casting doubt on the syndrome's traditional name. Angioplasty and stenting of the subclavian artery resulted in the immediate disappearance of angina and continuous benefit at a follow-up of 3-32 months. The subclavian coronary steal syndrome, although rare, is a severe condition readily treated by angioplasty and stenting.     

Internal mammary artery steal syndrome secondary to a para-IMA after coronary artery bypass graft： a case report

Introduction
The use of the intemal mammary artery （IMA） in coronary artery bypass graft（CABG） for myocardial revascularization is gaining popularity in routine practice, especially when the target vessel is the left anterior descending artery （LAD）. Occasionally, IMA hypoperfusion occurs when there is inadequate flow through the IMA graft to the LAD artery due to the exist of lateral branches.     

Repeat embolization of the side branch of the internal mammary artery graft by gelatin sponge particles and micro coils

The internal mammary artery (IMA) is increasingly used as a coronary bypass conduit because of better long-term patency and improved prognosis as compared with venous grafts. Previous investigators have suggested that the “steal” of blood flow of the IMA graft via the subclavian artery or a persistent large side branch of the graft may lead to its thinning. However, only a few reports have described the embolization of a large side branch using a transcatheter procedure. We present a case of repeated embolization of a large lateral costal side branch of the left internal mammary arterial graft applying gelatin sponge particles and micro coils, as well as angioplasty to the graft conduit, with resulting easing of chest pain.     

A case of Coronary-Subclavian Steal Syndrome

Surgical bypass of left coronary artery disease using the internal mammary artery (IMA) as a conduit is standard practice. Adequate blood supply to the IMA is dependent on normal flow in the subclavian artery. Stenosis of the subclavian can impair coronary supply from the internal mammary artery. This may create a steal syndrome whereby the left arm may rob the coronary system of flow especially during arm exercise. In the present report a case of angina with left coronary system steal via an internal mammary graft due to atherosclerotic subclavian stenosis. Successful treatment of the anginal symptoms by native coronary stenting is described.     

Coronary steal due to bilateral internal mammary artery--pulmonary artery fistulas: a rare cause of chest pain after coronary artery bypass grafting.

A 54-year-old man with a history of coronary artery bypass grafting (CABG) presented with chest pain and was found to have non-ST-segment elevation myocardial infarction. Left heart catheterization with coronary angiography demonstrated 100% occlusion of the right internal mammary artery (IMA) to the right coronary artery graft in its midsegment and a patent left IMA to the left anterior descending graft. An unusually large extensive fistulous collateral formation was observed between the right IMA and the left IMA to the pulmonary arterial system, causing left to right shunting. His angina was attributed to substantial coronary steal caused by the shunt. The patient refused any further intervention or surgery and opted for medical treatment. As a complication of CABG, IMA to pulmonary artery (PA) fistulas are rare. Thus far, more than 20 cases have been reported; most have been unilateral. This is the second reported case to date of bilateral IMA-PA fistula formation after CABG. An IMA-PA fistula should be considered in the differential diagnosis of patients presenting with chest pain after CABG and can be diagnosed by selective angiography of IMA grafts.     

乳内动脉在冠状动脉旁路移植术中的应用

为了探索国人应用乳内动脉做冠状动脉旁路移植术的近期临床效果,从94年10月至98年3月共60例冠心病人采用乳内动脉、桡动脉及大隐静脉做冠状动脉旁路移植术(CABG).大多数为三支病变及左主干病变.中低温及常温体外循环,经主动脉根部间断灌注冷血或温血停跳液心肌保护.强调在取乳内动脉时要格外小心,不要用器械钳夹乳内动脉,牵拉应轻柔.采用8-0 Prolene线做乳内动脉与前降支等做远端吻合.吻合完成后应将乳内蒂固定于心脏表面,减少吻合口张力.最后切开左上心包让乳内动脉走行平坦,无张力.平均搭桥支数为3.5根.术后死亡1例,死亡率1.7%.使用乳内动脉做CABC是安全有效的.59例病人心绞痛完全缓解,活动能力及生活质量明显提高.     

Internal mammary artery atherosclerosis in segments removed during coronary artery bypass grafting surgery and C.pneumoniae infection.

OBJECTIVE: Recent studies suggest the association of atherosclerotic cardiovascular disease with Chlamydia pneumoniae infection. We investigated C. pneumoniae DNA in internal mammarian artery (IMA) (used as a coronary bypass conduit) and its relationship with atherosclerosis. METHODS: Sixty-six consecutive patients who underwent coronary artery bypass grafting (CABG) during an eight-month period were included in this study. From all patients, we attempted to obtain surplus segments of harvested IMA grafts. The vessels were examined histopathologically, and presence of C. pneumoniae DNA in IMA grafts was assessed by polymerase chain reaction (PCR). RESULTS: C. pneumoniae DNA was found in 7 (10.6%) of 66 IMA specimens. The light microscopic examinations of IMA segments from the C. pneumonia positive group showed atherosclerotic intimal changes in four of the seven patients. These atherosclerotic changes were type II in three patients and type III in one patient according to the AHA classification. The rest of the IMA segments from 62 patients did not show any discernible atherosclerotic lesion. CONCLUSION: The IMA graft examination by PCR and histopathology may be helpful in the determination of future graft patency for IMA bypass surgery.     

Retrograde internal mammary to coronary artery anastomoses

In an effort to expand the utilization of the internal mammary artery (IMA) for revascularization of the distal coronary artery branches, distally pedicled retrograde internal mammary arteries (retro-IMA) were evaluated in 10 mongrel dogs with a mean weight of 38 +/- 13 kg. One IMA was transected at it's origin (retro-IMA) and compared to the contralateral IMA which was transected at the level of the 5th intercostal space. At a mean systemic pressure of 68 +/- 15 mmHg the mean pressure measured at the tip of the IMAs with antegrade flow was 63 +/- 14 mmHg in the retro-IMAs with retrograde flow (p less than 0.05; pressure ratio 0.8). With the same mean systemic pressure, mean antegrade free flow of the IMAs was assessed 97 +/- 43 ml/min versus 48 +/- 13 ml/min in the retro-IMAs with retrograde flow (p less than 0.005; flow ratio 0.5). Left retro-IMA to coronary artery anastomosis was performed in 6 animals to the distal left anterior descending (LAD) coronary artery and in 2 animals to the distal left obtuse marginal branch. Right retro-IMA to coronary artery anastomosis to the right posterior descending coronary artery was performed in 2 animals. The LAD coronary artery was ligated proximally to the retro-IMA to coronary artery anastomosis while the retro-IMA remained crossclamped. After documentation of significant ischemia (EKG, left atrial pressure), the crossclamp of the retro-IMA graft was removed. Subsequent normalisation of EKG and left atrial pressure occurred in all animals. We conclude that the canine retro-IMA delivers significant retrograde flow and discuss a possible use in humans.     

Anastomosis of small arteries: implications for coronary artery grafts in Asians

The internal mammary artery (IMA) in patients with small body surface area, frequently found in the Asian population, is often small and delicate and can be easily damaged during suturing, particularly at the "toe" of the anastomosis. This may lead to less frequent utilization of the IMA as a bypass conduit. We describe a technique for anastomosing a small-caliber IMA to a coronary artery, using the tip of the graft as an autologous buttress to reinforce the toe of the anastomosis.     

Long-term patency of saphenous vein and left internal mammary artery grafts after coronary artery bypass surgery: results from a Department of Veterans Affairs Cooperative Study

OBJECTIVES: This study defined long-term patency of saphenous vein grafts (SVG) and internal mammary artery (IMA) grafts. BACKGROUND: This VA Cooperative Studies Trial defined 10-year SVG patency in 1,074 patients and left IMA patency in 457 patients undergoing coronary artery bypass grafting (CABG). METHODS: Patients underwent cardiac catheterizations at 1 week and 1, 3, 6, and 10 years after CABG. RESULTS: Patency at 10 years was 61% for SVGs compared with 85% for IMA grafts (p < 0.001). If a SVG or IMA graft was patent at 1 week, that graft had a 68% and 88% chance, respectively, of being patent at 10 years. The SVG patency to the left anterior descending artery (LAD) (69%) was better (p < 0.001) than to the right coronary artery (56%), or circumflex (58%). Recipient vessel size was a significant predictor of graft patency, in vessels >2.0 mm in diameter SVG patency was 88% versus 55% in vessels 2.0 mm in diameter.     

Measures to increase the number of mammary artery coronary artery anastomoses

Patients with single internal mammary artery (IMA) grafts along with saphenous vein grafts have been found to have fewer coronary events and longer survival after operation. To reduce bypass graft failure from intimal hyperplasia and atherosclerosis, as well as to improve results, three or more IMA grafts were placed in 215 patients from October 1982 through May 1985. Careful planning helped in bypassing the maximum number of coronary artery obstructions with arterial conduits. By using bilateral IMA grafts, sequential, and Y grafts, the number of IMA coronary artery anastomoses increases and the need for saphenous vein grafts decreases. Meticulous dissection and preparation of the entire IMA and proper construction of the anastomosis are essentials for these procedures to be successful. Two of the 215 patients died early and four died late. Ninety-five percent of the postoperative stress tests were negative and 92% of the 39 IMA grafts visualized in 13 patients studied postoperatively were patent. We found this to be a safe, challenging procedure that improved late bypass conduit success and prolonged survival.     

Results of internal mammary artery-coronary artery bypass surgery and the characteristics of internal mammary artery grafts

Coronary artery bypass grafting utilizing the internal mammary artery (IMA) was performed in 108 patients with an operative mortality (less than 1 month) of 0% and a hospital mortality of 1.9%. The IMA was used most often in the left anterior descending artery system in combination with saphenous vein grafts (SVG) to the right and left circumflex artery systems. Although the IMA flow was smaller than the SVG flow when measured intraoperatively by an electromagnetic flow meter, postoperative clinical, electrocardiographic, isotopic, angiographic and coronary sinus flow-metric studies all demonstrated that the IMA can respond well to myocardial blood flow demand both at rest and during exercise, resulting in excellent clinical improvements with no detectable signs of flow deficiency. In addition, no signs of ischemia were detected in any of the 15 patients with stenosis in the left main trunk treated with an IMA graft. The IMA graft appears to have a great adaptive capacity to meet increased myocardial demand. Postoperative angiography performed at an average of 3 months after surgery in 60 unselected patients demonstrated an IMA patency rate of 98% in comparison with 88% patency in SVGs to the left anterior descending artery (p less than 0.05). Not only the patency rate, but also the graft wall characteristics were much better in IMA grafts than in SVGs. Some SVGs showed marked wall irregularity as early as 3 months after surgery.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hemodynamics and coronary blood flow during exercise after coronary artery bypass grafting with internal mammary arteries in children with Kawasaki disease

BACKGROUND. Saphenous vein grafts (SVG) and internal mammary artery (IMA) grafts have been used for coronary artery bypass grafting. In adult patients with bypass grafting for atherosclerotic coronary artery disease, IMA grafts have been reported to have long-term patency; however, results are conflicting on whether the graft is sufficient to meet increased myocardial oxygen demand during exercise. There have been no studies on hemodynamics and blood flow during exercise after bypass grafting with IMA in pediatric patients with Kawasaki disease. METHODS AND RESULTS. We studied 17 pediatric patients with Kawasaki disease (average age, 7.5 +/- 3.1 years), who underwent coronary artery bypass grafting with the IMA. The average number of coronary artery bypass grafts was 2.1 +/- 0.7/patient. For all patients, the left IMA was anastomosed to the left anterior descending coronary artery; for eight patients, the right IMA was also anastomosed to the right coronary artery. In addition, 11 SVGs were used. The postoperative patency rates after 1 month were 100% with the IMA graft and 91% with SVG. One year after the operation, the patency rates were 100% with IMA and 50% with SVG. Hemodynamics during exercise were measured with a bicycle ergometer, and coronary sinus blood flow was measured by the continuous thermodilution method in six patients. The relation between delta LVEDP (the difference between left ventricular end-diastolic pressure at rest and during exercise) and delta SVI (the difference between the stroke volume index at rest and during exercise) was analyzed. Four of six patients had reduced cardiac function before operation (delta LVEDP, positive; delta SVI, negative). However, after the operation, all patients demonstrated improvements in cardiac function during exercise (delta LVEDP, positive; delta SVI, positive). Coronary sinus flow per left ventricular mass increased after operation from 70 +/- 46 to 87 +/- 56 ml/min at rest (p less than 0.05) and from 139 +/- 118 to 183 +/- 150 ml/min during exercise (p less than 0.05). CONCLUSIONS. In conclusion, this study reveals improvements in both hemodynamics and coronary blood flow during exercise after coronary artery bypass grafting with IMA grafts in pediatric patients with Kawasaki disease.     

全动脉化冠状动脉旁路移植74例

目的:介绍全动脉化冠状动脉旁路移植（CABG）的早期效果和经验。方法:74例全动脉化CABG的患者。74例患者分别在体外循环（CPB）和非CPB下行CABG。应用左乳内动脉（IMA）1例,左IMA加单挠动脉（RA）14例,左IMA加双RA 54例,双IMA加双RA 3例,双RA 2例。人均搭桥4.7（17）支,序贯吻合66例,“Y”和“T”型吻合分别为15和6例。结果:围手术期无死亡。本组患者随访518（平均12.2）个月,均恢复良好,无心绞痛症状再发。多普勒和16排CT示血管桥无狭窄通畅。结论:全动脉化CABG取得好的早期效果,是一种值得积极推广的方法。     

Using the internal thoracic artery of patients with reduced left ventricular function

Todate internal mammary artery (IMA) is routinely used in coronary artery bypass grafting even in elder patients. However in patients with poor left ventricular function use of the IMA is discussed controversely in Germany. Main arguments against IMA are an increased operation time, initially lower blood flow, higher rates of reoperation for bleeding and more perioperative complications. In this study we investigated use of the IMA in patients with poor left ventricular function (LVEF < 40%) compared to exclusively veingraft bypass surgery. 137 patients (105 m/32 f) suffering from coronary artery disease with reduced LVEF (12-40%) were randomized in the study. 67 patients received exclusively vein grafts (group I), 70 patients routinely obtained an IMA graft. Criteria used for evaluation of IMA graft were operation time, postoperative bleeding, need for catecholamines, requirement of intensive care, perioperative myocardial infarction and mortality. The number of distal anastomoses in each group was 3.1 (2-5). The operation time varied in compliance with the number of distal anastomoses, but there were no significant differences between both groups. Postoperative bleeding until the second postoperative day was 905 ml in group II versus 569 ml in group I; the difference was significant (p < 0.05). The need of catecholamines after operation and hemodynamic parameters were comparable in both groups, there were no significant differences. Intensive care was required for a mean of 1.6 days in both groups, postoperative ventilation was 5.8 hours in group I versus 7.9 hours in group II, differences not significant. Ischemia or myocardial infarction could be demonstrated in 2 patients of group I (3%) versus 4 patients of group II (5.7%). The differences between the groups were not significant. Cardiac low output syndromes without sights of myocardial infarction were apparent in 9 patients of group I (13.5%) versus 2 patients of group II (2.9%), this difference being significant (p < 0.05). Mortality after operation in both groups was higher than in patients with normal ventricular function, however the differences between the evaluated groups were not significant (5.9% in group I versus 4.3% in group II). Summarizing the above it can be concluded that patients with poor left ventricular function are at a higher risk when subjected to bypass operation; the use of IMA did not show any disadvantages in comparison to exclusively veingraft surgery, except of a higher perioperative bleeding risk. Due to better long term results IMA should be used routinely also in bypass-patients with poor left ventricular function.