Right gastroepiploic-to-coronary artery bypass. The first decade of use

Distribution of Perigastric Station 4d Lymph Nodes in Vascularized Gastroepiploic Lymph Node Transfer: An Anatomic Study and Case Series

BACKGROUND

Vascularized gastroepiploic lymph node transfer (VGLNT) is a well-accepted surgical treatment for restoring physiological function in chronic lymphedema. However, the inclusion of substantial lymph nodes (LNs) in the flap remains uncertain. This study aimed to identify the anatomical basis for reliable flap harvest for VGLNT.

PATIENTS AND METHODS

The anatomy of perigastric station 4d LNs was studied in healthy cadavers (n = 15) and patients with early gastric cancer (EGC) (n = 27). The omentum was divided into three segments: proximal, middle, and distal from the origin of the right gastroepiploic vessels. The flap dimension, number, location, size of LNs, and caliber of the vessels were reviewed. Eight patients underwent VGLNT for upper/lower limb lymphedema.

RESULTS

The mean numbers of LNs in the proximal, middle, and distal segment were 2.5, 1.4, 0.5 in the cadavers, and 4.9, 2.7, 0.7 in the gastrectomy specimens, respectively. The proximal third included a significantly greater number of LNs than the distal third in the cadaveric (p = 0.024) and ECG (p = 0.016) specimens. A total of 95% of the LNs were located within proximal two-thirds of the flap from the vessel origin both in the cadavers (21.0 × 5.0 cm) and in the gastrectomy specimens (20 × 3.5 cm). In VGLNT, the transferred flap was 25.5 ± 6.9 × 4.1 + 0.7 cm in dimension, containing a mean number of 6.5 ± 1.9 LNs. At postoperative 6 months, the volumetric difference was significantly reduced by 22.8 ± 9.2% (p < 0.001).

CONCLUSIONS

This study provides a distinct distribution pattern of station 4d LNs. Inclusion of the proximal two-thirds of the flap, which carries majority of the LNs, is recommended for VGLNT.

The laparoscopic right gastroepiploic lymph node flap transfer for upper and lower limb lymphedema: Technique and outcomes

BACKGROUND

Lymph node flap transfer popularity for treatment of extremity lymphedema is increasing quickly. Multiple flap donor sites were described in search of the optimal one. We describe the technique and outcomes of a laparoscopically harvested right gastroepiploic lymph node flap for treatment of extremity lymphedema.

METHODS

From January 2012 to January 2013, 10 consecutive female patients, average age 54.8 years, with International Society of Lymphology stage II-III extremity lymphedema refractory to conservative management were included. Five patients had upper limb breast cancer-related lymphedema and five patients had lower limb pelvic cancer-related lymphedema. All patients underwent laparoscopic harvest of the right gastroepiploic lymph node flap, transferred to the wrist and ankle as recipient sites. Flaps were covered with a small skin graft taken from the thigh. Perioperative assessment included physical exam, photography, circumference measurements, CT scans, lymphoscintigraphy, and Lymphedema Quality of Life (LYMQOL) questionnaire. Clinical and CT evaluation of donor-site morbidity were performed.

RESULTS

The flap survival rate was 100%, with a mean harvest time of 32 minutes and total operating time of 164 minutes. One case required regrafting for skin graft loss. The mean limb reduction rate was 39.5% at a mean follow-up of 14.7 months. Perioperative lymphoscintigraphy demonstrated transferred lymph node viability and lymphatic transport improvement. LYMQOL showed a 2.6-fold quality-of-life improvement (P < 0.01). No donor-site morbidity was encountered.

CONCLUSIONS

The use of the laparoscopically harvested right gastroepiploic lymph node flap may be a safe technique that improves limb measurements and quality of life in extremity lymphedema patients. © 2015 Wiley Periodicals, Inc. Microsurgery 37:197-205, 2017.

Celiac artery stent placement for coronary ischemia

INTRODUCTION

The use of endovascular technology for mesenteric interventions has become an increasingly accepted treatment modality. We present an unusual case of celiac artery stent placement for coronary ischemia.

CASE DESCRIPTION

A 66-year-old male with a history most notable for coronary artery disease and coronary artery bypass grafting (CABG) x 3 utilizing left internal mammary artery to left anterior descending, radial artery to first diagonal and his right gastroepiploic artery (GEA) to posterior descending artery presented with chest pain. His work-up included a cardiac catheterization that revealed a 90% stenosis at the origin of the celiac axis. A subsequent computerized tomography angiogram confirmed this and noted moderate stenosis of his superior mesenteric artery (SMA) as well as severe inferior mesenteric artery (IMA) stenosis. The patient was taken for mesenteric angiography by vascular surgery at which time he underwent balloon-expandable stent placement in the celiac axis. The patient tolerated this procedure well and was noted to have an improvement in his symptoms postoperatively.

DISCUSSION

Use of arterial conduits for CABG have proven to be superior to vein. Long-term viability of the GEA as a conduit is dependent in part on the patency of mesenteric circulation. Our findings demonstrate a viable endovascular treatment option for angina pectoris secondary to mesenteric stenosis in this unique patient population.

Significance of preoperative evaluation of the right gastroepiploic artery graft to the coronary artery in patients undergoing abdominal surgery

BACKGROUND

A major concern with the use of the right gastroepiploic artery (RGEA) as the graft for coronary artery bypass grafting (CABG) is the potential for injury, which can result in critical myocardial ischemia during future abdominal surgery.

METHODS

We examined the availability of preoperative image evaluation, preoperative recognition of the RGEA graft, and operative findings such as graft identification, graft injury, and cardiac events in 11 patients who underwent abdominal surgery after CABG using the RGEA as the graft.

RESULTS

Prior to the abdominal surgery, contrast-enhanced computed tomography (CT) was performed in all 11 patients, while coronary angiography or three-dimensional CT angiography was performed in five patients. We detected the RGEA graft retrospectively in nine of ten patients in whom the images from contrast-enhanced CT were still available. Among the seven patients whose RGEA grafts were in the operative field, the RGEA graft was identified in five patients, while the RGEA graft was not identified in the remaining two patients because of adhesions. There were no intraoperative cardiac events in any of the 11 patients.

CONCLUSIONS

It is important to determine whether an RGEA graft is present when repeat laparotomy is required after CABG. In cases where an RGEA graft is present, it is essential to evaluate the patency and location of the graft since this will be crucial for planning the reoperation strategy. Preoperative recognition and evaluation of the RGEA graft can help avoid graft injury, even if the graft cannot be detected intraoperatively.

Histological and Morphometric Properties of Skeletonized Gastroepiploic Artery and Risk Factors for Intimal Hyperplasia

Objective

The aim of the present study was to examine the histological and morphometric properties of skeletonized gastroepiploic artery (GEA) and the risk factors for intimal hyperplasia.

Methods

We obtained the redundant distal segments of skeletonized GEAs from 33 patients undergoing coronary bypass surgery and microscopically examined the transverse sections just distal to the most distal anastomoses. Intimal hyperplasia was evaluated on the basis of intima-to-media ratio and percentage of luminal narrowing. Risk factors were examined using multivariate linear regression analysis.

Results

The median (range) of lumen diameter at the most distal anastomosis was 3.8 (2.4–6.4) mm; width of intima, 82 (8–418) μm; width of media, 167 (88–351) μm; wall thickness, 250 (118–554) μm; intima-to-media ratio, 0.59 (0.04–3.88), and percentage of luminal narrowing, 12.3 (1.5–28.9). The number of elastic lamina in the media was 4.2 ± 1.8. Atherosclerosis was found in six patients, and medial calcification, in three patients. The median (range) of graft flow and pulsatile index measured by intraoperative transit-time flow meter was 65 (11–141) mL/min and 3.1 (1.4–5.9), respectively. All GEA grafts were patent at the coronary computed tomography angiography before discharge. Estimated glomerular filtration rate was independently associated with intima-to-media ratio (β coefficient = −0.016, P < 0.01) and percentage of luminal narrowing (β coefficient = −0.012, P < 0.01).

Conclusions

Skeletonized GEA had sufficient lumen diameter with excellent graft flow and early patency even when used as a sequential graft. Estimated glomerular filtration rate correlates significantly with intimal hyperplasia.

Cardiac tamponade caused by incarcerated small bowel in the pericardium after coronary bypass grafting using the right gastroepiploic artery

Although rare, herniation of the gastrointestinal contents into the pericardium after coronary artery bypass grafting using the right gastroepiploic artery has been previously described. The associated clinical symptoms vary from gastrointestinal obstruction to cardiac tamponade. We report a patient who presented with cardiac tamponade secondary to incarceration of the small bowel in the pericardium 1 year after coronary artery bypass grafting utilizing the right gastroepiploic artery.

En-bloc free gastroepiploic artery graft provides a good long-term patency rate

For coronary artery bypass grafting, the use of free gastroepiploic artery is unpopular because of its tendency to vasospasm. We assessed the en-bloc free gastroepiploic artery graft, which has the gastroepiploic vein anastomosed to the right atrial appendage to prevent graft spasm, and compared it to the skeletonized free gastroepiploic artery graft. A retrospective review was conducted in 57 patients who received en-bloc grafts and 29 who had skeletonized grafts. Kaplan-Meier analysis demonstrated the superiority of the en-bloc free gastroepiploic artery graft with an 80-month patency rate of 96.6% compared to 66.7% with skeletonized grafts. We selected 13 cases from each group, using propensity-score matching, and compared the long-term patency rates. Propensity-score matched analysis showed 80-month patency rates of 100% for en-bloc grafts and 60% for skeletonized grafts. Coronary artery bypass using free gastroepiploic artery grafts with venous drainage seems to provide good long-term results.

Effects of ultrasonic skeletonization of the gastroepiploic artery on endothelial nitric oxide production

OBJECTIVE

: The right gastroepiploic artery (GEA) is a reliable conduit for coronary artery bypass grafting. Recently, ultrasonic skeletonization in graft harvesting has attracted attention as an alternative technique to increase the length and caliber size of grafts. The influence of GEA skeletonization using an ultrasonically activated device with that using an electrosurgical unit was compared from the viewpoint of production of nitric oxide (NO).

METHODS

: Fourteen pigs were used in this study. The GEA were harvested using an ultrasonically activated device (group ultrasonically activated device [USAD], n = 7) or electrocautery (group E, n = 7). Blood sampling was performed at the following three times from the distal end of the GEA: (1) preskeletonization, (2) pedicle, and (3) postskeletonization. Plasma NOx (NO metabolites) levels were measured by chemiluminescent assay. Moreover, in excised specimens, the expression of nitric oxide synthase was examined immunohistologically.

RESULTS

: In group USAD, the preskeletonization basal level of plasma NOx in GEA was 25.7 ± 10.9 μmol/L, which then increased to 26.9 ± 10.5 μmol/L (pedicle) and 32.2 ± 12.1 μmol/L (postskeletonization). In group E, the preskeletonization basal plasma NOx level in GEA was 28.9 ± 11.4 μmol/L, which changed to 27.5 ± 8.9 μmol/L (pedicle) and 21.8 ± 8.3 μmol/L (postskeletonization). The results of multivariate analysis indicated that the patterns of changes in plasma NOx level were significantly different in both groups (P = 0.024). In group USAD, post hoc multiple comparison tests revealed a significant difference between preskeletonization and postskeletonization (P = 0.037).

CONCLUSIONS

: Ultrasonically skeletonized GEA showed increased effective graft length, higher free flow capacity, and increased endothelial NO production than that prepared using an electrosurgical unit.

Skeletonization of radial and gastroepiploic conduits in coronary artery bypass surgery

The use of a skeletonized internal thoracic artery in coronary artery bypass graft surgery has been shown to confer certain advantages over a traditional pedicled technique, particularly in certain patient groups. Recent reports indicate that radial and gastroepiploic arteries can also be harvested using a skeletonized technique. The aim of this study is to systematically review the available evidence regarding the use of skeletonized radial and gastroepiploic arteries within coronary artery bypass surgery, focusing specifically on it's effect on conduit length and flow, levels of endothelial damage, graft patency and clinical outcome. Four electronic databases were systematically searched for studies reporting the utilisation of the skeletonization technique within coronary revascularisation surgery in humans. Reference lists of all identified studies were checked for any missing publications. There appears to be some evidence that skeletonization may improve angiographic patency, when compared with pedicled vessels in the short to mid-term. We have found no suggestion of increased complication rates or increased operating time. Skeletonization may increase the length of the conduit, and the number of sequential graft sites, but no clear clinical benefits are apparent. Our study suggests that there is not enough high quality or consistent evidence to currently advocate the application of this technique to radial or gastroepiploic conduits ahead of a traditional pedicled technique.

Flow capacity of gastroepiploic artery versus vein grafts for intermediate coronary artery stenosis

BACKGROUND

Native flow competition is a significant factor affecting bypass graft patency. The objective of this study was to compare the effect of competitive flow on conduit flow dynamics in the gastroepiploic artery (GEA) and the saphenous vein graft (SVG).

METHODS

In 51 patents, 23 GEAs (in-situ grafts) and 28 SVGs (aortocoronary grafts) were examined using a Doppler-tipped guidewire during coronary angiography after coronary artery bypass. Graft flow volume at rest and maximum graft flow volume during hyperemia were calculated from graft diameter and average peak velocity at rest and maximum average peak velocity induced by papaverine hydrochloride injection. Grafts were classified according to the grade of native coronary artery stenosis; group S (14 GEAs and 16 SVGs) displayed over 75% stenosis and group M (9 GEAs and 12 SVGs) exhibited over 50% up to 75% stenosis.

RESULTS

In group S, no difference in flow volume was apparent between the GEA and the SVG at rest (36+/- 17 vs 42 +/- 16) and during hyperemia (78 +/- 30 vs 88 +/- 28). In group M, flow volume of the GEA was significantly lower than that of the SVG at rest (17 +/- 11 vs 38 +/- 12; p = 0.029) and during hyperemia (32 +/- 19 vs 94 +/- 46; p = 0.001).

CONCLUSIONS

These data suggest that in intermediate coronary stenosis, GEA flow is compromised by native flow competition, whereas the SVG flow dynamics is maintained. However, the GEA can provide comparable flow capacity to the SVG and will achieve good surgical results when target coronary artery selection is appropriate.

Skeletonization of gastroepiploic artery graft in off-pump coronary artery bypass grafting: early clinical and angiographic assessment

BACKGROUND

Recently skeletonization has been recognized as an alternative to pedicle harvesting of the internal thoracic artery as a technique that increases the length and caliber size of the graft compared with pedicled internal thoracic artery grafts; however, this is not yet popular for harvesting the gastroepiploic artery (GEA). We report here our experience of skeletonized GEA grafting in off-pump coronary artery bypass grafting with early clinical and angiographic results. The purpose of this study was to evaluate skeletonization of GEA grafting in off-pump coronary artery bypass grafting with a large patient volume.

METHODS

One hundred sixty-eight patients including 131 men and 37 women (mean age, 65 years; range, 45 to 87 years) underwent the skeletonized GEA grafting in off-pump coronary artery bypass grafting. These patients represent 41% (168 of 407 patients) of those who underwent off-pump coronary artery bypass grafting operations during the same period. We used the GEA graft of choice in patients with right coronary artery lesion. Skeletonization was performed in a unique manner we developed.

RESULTS

There were no in-hospital deaths among the study patients. One patient had a perioperative myocardial infarction, which was considered a result of vasospasm of the GEA graft. None of the other patients had severe morbidity. The patency rate of the skeletonized GEA graft was 98.1% (151 of 154 distal anastomoses).

CONCLUSIONS

This study suggests that skeletonization of the GEA graft can enlarge its caliber size and improve its flow capacity. In addition, the acceptable early clinical and angiographic outcome suggests that use of the skeletonized GEA graft in off-pump coronary artery bypass grafting surgery is safe and effective.

Existence of alpha-adrenoceptor subtypes in isolated human gastroepiploic and omental arteries

Establishing the existence of alpha-adrenoceptor subtypes in isolated human gastroepiploic and omental arteries was the goal of the present study. Functional vascular reactivity of selective alpha(1)- and alpha(2)-adrenoceptor agonists and antagonists was studied, using a cannula inserting technique. Intraluminal administration of norepinephrine (NE), phenylephrine (PE) or BHT-933 caused a vasoconstrictive response in a dose-related manner. The relative potencies of the 3 agonists were almost the same in both arteries. NE-induced vasoconstrictions were significantly antagonized by either prazosin or rauwolscine. PE-induced responses were strongly inhibited by prazosin. BHT-933-induced constrictions were inhibited by rauwolscine. These results indicate that both alpha(1)- and alpha(2)-adrenoceptors exist in the human gastroepiploic and omental arteries.

[Coronary artery surgery in diabetic patients]

Currently, 15% to 30% of the patients that undergo coronary artery surgery are diabetics. As a group, they have less favorable anatomic and clinical characteristics than the general population. Specifically, diabetics have more extensive coronary disease, more vessels involved, and more diffuse stenosis, so they need a higher number of distal anastomoses to achieve complete revascularization. In spite of these drawbacks, they can undergo coronary artery bypass procedures with an operative mortality similar to that of non-diabetic patients. However, some postoperative complications are significantly more prevalent among diabetics, mainly renal failure, neurological accidents, sternal dehiscence, and infection. In early studies of the late results of surgical revascularization, mainly based on venous grafts, late survival and clinical improvement were less satisfactory in diabetics than in non-diabetics. However, in recent experiences, in which the internal mammary artery has been used extensively, the clinical outcome of diabetics has been similar to that of non-diabetics, confirming this procedure as the preferred one in revascularizing the coronary arteries of diabetics with multivessel disease. Off-pump surgery and extensive use of arterial grafts are becoming established strategies for reducing operative risk and improving long-term clinical results. However, continuous, strict medical management of hyperglycemia and other known coronary risk factors, especially lipid levels, is essential.

Coronary revascularization in the 21st century. Emphasis on contributions by Japanese surgeons

The first three decades of coronary artery surgery have provided the foundation for the next century of this evolution. It is apparent that a multitude of events including the development of cardioplegia, improving surgical instrumentation, technological advances including endoscopic approaches and computer assisted robotics and biologic discoveries such as the role of the endothelium have provided the underpinnings for improved surgical outcomes. However, the single most important determinant of late results is the type of bypass conduit used for grafting. Thus, use of the left internal thoracic artery (ITA) grafted to the left anterior descending coronary is a more important determinant of survival than is any other factor (progression of coronary artery disease, increased age, poor left ventricular function, diabetes, female gender and off-pump operations). Use of two ITAs provides further benefit and it is likely that three or more arterial conduits will be shown to be advantageous in this regard in due time. Japanese cardiothoracic surgeons have made significant contributions to the continuing evolution of coronary bypass surgery and particularly to the advance of arterial conduits. This report will address those contributions to this evolution.

Skeletonization of the right gastroepiploic artery using an ultrasonic scalpel

A new method to skeletonize and harvest the right gastroepiploic artery using an ultrasonic scalpel is presented. The technique is simple and safe, and it causes less bleeding. It is possible not only to harvest the artery faster, but to obtain large spasm-free arterial conduits for coronary artery bypass grafting.

Creative arterial bypass grafting can be performed on the beating heart

BACKGROUND

To demonstrate that compromise is unnecessary in either the design or performance of beating heart surgery, we report our experience, over 1 year, of total arterial revascularization where composite or creative grafting was utilized.

METHODS

We performed 321 off-pump coronary artery bypass operations, of which, 290 (90%) were done with only arterial conduits. The mean number of distal anastomoses was 2.48, with a range of 1 to 5. There were no aortic anastomoses. One hundred eighty-nine patients (65%) were male, and 101 (35%) were female, with a mean age of 67 years. Comorbidities included chronic renal failure (CRF), 21 (7%); diabetes, 92 (32%); obesity, 68 (23%); hypertension, 212 (73%); chronic obstructive pulmonary disease, 189 (65%); cerebral vascular accident (CVA), 39 (13%); smoking, 164 (56%); and hypercholesterolemia, 151 (52%). The mean ejection fraction was 56%, with a range of 21% to 71%. All procedures were performed with external stabilizers with or without vacuum assist. The complete arterial revascularizations included a T-graft (internal thoracic [ITA]/radial arteries [RA]), 130 (45%); a sequential graft (ITA +/- RA), 118 (41%); a U-graft (coronary-coronary graft perfused by the ITA or right gastroepiploic artery), 5 (2%); an I-graft (ITA/RA), 4 (1%); an X-graft (ITA/RA), 2 (12); and a Y-graft (ITA/RA), 31 (10%).

RESULTS

The postoperative incidence of atrial fibrillation was 80 of 290 (27%); CVA, 5 of 290 (2%); bleeding resulting in take-back, 5 of 290 (2%); CRF, 8 of 290 (3%); deep sternal infection, 4 of 290 (1%); and readmission (30-day) for angina, 4 of 290 (1%). The observed perioperative (30-day) mortality was 9 of 290 (3.1%), with the STS predicted rate of 3.82%.

CONCLUSIONS

Our experience indicates that once the operating surgeon has learned to safely expose the lateral and inferior walls of the heart, the type of conduit and the method of revascularization should be no different than that used with cardiopulmonary bypass. However, we still recommend conventional methods of revascularization (on-pump with saphenous vein conduits) for the ischemic patient.

Limited flow capacity of the right gastroepiploic artery graft: postoperative echocardiographic and angiographic evaluation

BACKGROUND

The flow capacity of the right gastroepiploic artery graft has not been clarified.

METHODS

Angiographic and echocardiographic studies were conducted in 30 patients who had undergone coronary artery bypass grafting using both the internal thoracic and right gastroepiploic arteries. The luminal diameter of the arterial grafts was measured from the postoperative angiograms. The adequacy of the myocardial blood supply from the arterial grafts was evaluated by dobutamine stress echocardiography.

RESULTS

With echocardiography, 14 patients exhibited an ischemic response in the gastroepiploic artery grafted region, whereas no patients exhibited an ischemic response in the internal thoracic artery grafted area. The luminal diameter of the gastroepiploic artery and a younger age were correlated with the ischemic response observed in the dobutamine stress echocardiography. A luminal diameter of the gastroepiploic artery of greater than 2.6 mm had the highest sensitivity and specificity for a nonischemic change.

CONCLUSIONS

To generate the maximal flow reserve, the luminal diameter of the gastroepiploic artery when used as a graft should be sufficiently large enough, nearly 3 mm at the anastomosis.

Noninvasive assessment of coronary flow reserve in the right gastroepiploic artery graft

BACKGROUND

To investigate the functional capacity of the right gastroepiploic artery graft (GEA) and its ability to adapt to provide adequate flow at peak myocardial demand, we investigated the feasibility of determining coronary flow reserve (CFR) provided by this vessel using transabdominal color Doppler echocardiography and the correlation between this noninvasive determination of flow reserve and nuclear stress scintigraphy.

METHODS

In 40 selected patients, who underwent complete arterial myocardial revascularization using the GEA and the internal thoracic arteries (ITAs), CFR of the GEA was measured at maximum coronary hyperemia induced by intravenous adenosine infusion, 7 months (range 3 to 20) after surgery. In the same period, in 31 of this group of patients, exercise thallium scintigraphy was performed.

RESULTS

We succeeded in measuring CFR in 37 of 40 patients with values ranging from 1.1 to 3.6 with an average of 2.1 +/- 0.7. During adenosine infusion, mean velocity in the GEA significantly increased from 48 +/- 20 to 89 +/- 41 cm/sec (p < 0.001), mean arterial blood pressure significantly decreased from 96 +/- 11 to 87 +/- 11 mm Hg (p < 0.001), and heart rate significantly increased from 74 +/- 11 to 87 +/- 15 beats/min (p < 0.001). In 8 of these 37 patients, the nuclear exercise test was positive (compatible with reversible ischemia in the distribution area of the GEA). Average CFR in these 8 patients with positive nuclear stress test was 1.46 +/- 0.28 versus 2.27 +/- 0.70 in those patients with a negative test (p < 0.001).

CONCLUSIONS

Noninvasive determination of CFR of GEAs is feasible, using transabdominal Doppler echocardiography. The present study shows that coronary vasodilator reserve and autoregulation is maintained in myocardium supplied by the GEA and that the CFR has a significant correlation with the results of noninvasive nuclear exercise testing. Therefore, noninvasive determination of CFR by transabdominal Doppler echocardiography might be a valuable contribution to functional assessment of GEAs.

Theoretical analysis of right gastroepiploic artery grafting to right coronary artery

BACKGROUND

The right gastroepiploic artery (GEA) has been used as the second reliable arterial graft for coronary artery bypass grafting (CABG). However, concern regarding the flow competition with the recipient coronary artery has remained.

METHODS

An application of in situ GEA grafting to the right coronary artery (RCA) was studied by using a theoretical model. The theoretical model of CABG was given variables; ie, the diameters and the lengths of both in situ GEA and proximal segment of the RCA, and the degree of proximal stenosis in the RCA. According to the range of these variables obtained from clinical data, the ratio of the GEA flow to the flow of the RCA distal to the anastomosis was calculated.

RESULTS

Main factors to determine the flows in the two parallel paths were the inner diameters of both vessels, and the degree of the proximal stenosis. When the inner diameters of the GEA were 0.5 mm larger than that of the RCA, the GEA carried more than 50% of the total flow of the RCA distal to the anastomosis despite a moderate stenosis in the RCA. When the inner diameter of the GEA was equal to, or 0.5 mm smaller than, that of the RCA, the GEA flow was dominated by the native RCA flow unless the proximal stenosis was critical.

CONCLUSIONS

If the inner diameter of the GEA is 0.5 mm larger than that of the RCA, CABG with the GEA can be applied more widely. If not, the application would basically be limited.

The continuing evolution of arterial conduits

Vineberg used the internal thoracic artery (ITA) to achieve indirect myocardial revascularization in 1950, and Green reported direct coronary anastomosis with an operating microscope in 1968. It was not until the early 1980s that superior 10-year patency compared with saphenous vein was established for the ITA. In 1986, Loop proved better patient survival at 10 years when the left ITA was grafted to the left anterior descending artery rather than vein in patients with triple-vessel disease having complete revascularization. Only in 1998 has Lytle shown enhanced survival with use of two ITAs over one in triple-vessel disease. This report came 4 months after a report showing no additional benefit from the second ITA. Increasingly, complex use of arterial conduits allows complete revascularization with two arterial conduits (both ITAs or one ITA and one radial artery) in most patients (with 10-year data soon to be available in the former). The T-graft configuration (ITA T-graft or radial T-graft) is highly complex and utilizes single-source inflow to the entire heart (in addition to native coronary flow), which may not provide adequate inflow and remains controversial. Although patency for the ITA is well established, this cannot be said for the radial artery (one report of 55 conduits to 5.5 years), the gastroepiploic artery (one report of 44 conduits to 7 years), or the inferior epigastric artery (one report of 154 conduits to 43 months). Long-term follow-up of each conduit and each configuration is required to prove its durability and, therefore, value in the operative management of coronary disease.

Initial experience with MIDCAB grafting using the gastroepiploic artery

BACKGROUND

Minimally invasive direct coronary artery bypass grafting with the gastroepiploic artery can be used in primary operations and reoperations to revascularize the inferior or anterior surface of the heart.

METHODS

Patients who had symptomatic coronary artery disease limited to a single coronary distribution were selected. Coronary targets were grafted with the pedicled gastroepiploic artery through a small midline epigastric incision. Patients were followed with scheduled outpatient clinic visits, Doppler examination, and selective recatheterization.

RESULTS

Between May 1995 and November 1997, 74 patients underwent gastroepiploic artery minimally invasive direct coronary artery bypass grafting; 33 (45%) had a primary operation and 41 (55%), a reoperation. Grafting was performed to the distal right coronary artery (n = 38), the posterior descending artery (n = 28), or the distal left anterior descending coronary artery (n = 8). There were six deaths (8%) within 30 days after operation. Twenty patients (28%) underwent recatheterization; there were two graft occlusions, two graft stenoses, and five anastomotic stenoses. Of 60 patients seen 2 or more weeks after operation, 53 (88%) had resolution of anginal symptoms at a mean follow-up of 10.9 months (range, 0 to 30 months).

CONCLUSIONS

Inferior minimally invasive direct coronary artery bypass grafting with the gastroepiploic artery avoids the risks of repeat sternotomy, aortic manipulation, and cardiopulmonary bypass. Patency rates, however, were lower than expected, and there is significant morbidity and mortality associated with high-risk patients undergoing the procedure. Continued follow-up is essential to evaluate long-term graft patency and patient survival.

Arterial grafting: techniques and conduits

The superior long-term patency and survival of the internal thoracic artery in coronary artery bypass grafting, compared with saphenous vein, established the internal thoracic artery as the conduit of choice for myocardial revascularization. Use of the internal thoracic artery has expanded, and the possibility of similar performance by other arteries has motivated surgeons to investigate alternative arterial conduits (eg, the gastroepiploic artery, inferior epigastric artery, and radial artery). Although these grafts have become more technically feasible and have shown benefits, more follow-up data are needed to determine the long-term patency, freedom from arteriosclerosis, and efficacy of alternative conduits.

Surgical myocardial revascularization

In conclusion, surgical myocardial revascularization has utilized diverse methods to increase blood flow to the starving myocardium. These methods initially used the microcirculation as the portal to reach myocytes until angiography showed that the obstructions were macrovascular. This resulted in a 30-year era of direct attack on the coronary blockages by coronary bypass. Surgical conduits unfortunately have longevity considerably less than that of native arteries and are limited in number. Alternative conduits, both biologic and prosthetic, have not yet proved to have the same clinical results as the ITA. More patients are living long enough to have the extensiveness of their disease exhaust conventional therapies. Newer therapy, restricted thus far to untreatables, revisits the microcirculation by making laser channels. These many innovative procedures have benefited hundreds of thousands of patients. They emerged from the probity and innovation of many individual surgeons.

Aortocoronary saphenous vein graft disease: pathogenesis, predisposition, and prevention

Aortocoronary saphenous vein graft disease, with its increasing clinical sequelae, presents an important and unresolved dilemma in cardiological practice. During the 1st month after bypass surgery, vein graft attrition results from thrombotic occlusion, while later the dominant process is atherosclerotic obstruction occurring on a foundation of neointimal hyperplasia. Although the risk factors predisposing to vein graft atherosclerosis are broadly similar to those recognized for native coronary disease, the pathogenic effects of these risk factors are amplified by inherent deficiencies of the vein as a conduit when transposed into the coronary arterial circulation. A multifaceted strategy aimed at prevention of vein graft disease is emerging, elements of which include: continued improvements in surgical technique; more effective antiplatelet drugs; increasingly intensive risk factor modification, in particular early and aggressive lipid-lowering drug therapy; and a number of evolving therapies, such as gene transfer and nitric oxide donor administration, which target vein graft disease at an early and fundamental level. At present, a key measure is to circumvent the problem of vein graft disease by preferential selection of arterial conduits, in particular the internal mammary arteries, for coronary bypass surgery whenever possible.

Minimally invasive coronary artery bypass grafting using the right gastroepiploic artery

BACKGROUND

Anastomosis of the left internal thoracic artery to the left anterior descending artery without sternotomy and without cardiopulmonary bypass is a standard approach in minimally invasive coronary artery bypass grafting. To expand the indications for minimally invasive coronary artery bypass grafting from one-vessel disease to two-vessel disease, we began to perform anastomosis of the right gastroepiploic artery (RGEA) to the right coronary artery (RCA).

METHODS

From February to November 1996, an RGEA graft was used in 25 of the 100 patients who underwent minimally invasive coronary artery bypass grafting at our clinic. Eleven of the patients had only RCA disease and 14 had both RCA and left anterior descending artery disease. One of the operations was a redo coronary artery bypass grafting. The RGEA was anastomosed to the RCA through a laparotomy incision and the left internal thoracic artery was anastomosed to the left anterior descending artery through a left anterior thoracotomy. In 5 patients, the RGEA was lengthened by venous grafting.

RESULTS

All patients underwent angiography after operation; 82.6% of the RGEA grafts and all the left internal thoracic artery grafts were functioning well. In three of the four nonvisualized RGEA grafts, the percentage of proximal stenosis of the RCA seen on postoperative angiography was not critical (40%, 50%, and 50%, respectively), allowing significant competitive flow through the native bypassed RCA. The patency of all the RGEA grafts without competitive flow was 95%, with a 95% confidence interval of 75.1% to 99.9%.

CONCLUSIONS

The indications for minimally invasive coronary artery bypass grafting could be extended to primary operations in patients with left anterior descending artery and RCA lesions by using both the left internal thoracic artery and the RGEA.

Morphometric study of the right gastroepiploic and inferior epigastric arteries

BACKGROUND

Based on earlier observations that the thickness of the intima and structure of the media may have an impact on the long-term patency of arterial conduits and the lack of detailed histologic studies of the right gastroepiploic and inferior epigastric arteries, we subjected both vessels to morphometric analysis with emphasis on their suitability as conduits in myocardial revascularization.

METHODS

The right gastroepiploic and inferior epigastric arteries were harvested from 28 unselected individuals (mean age, 73.2 years) at autopsy, and the luminal diameter and the width of the intima and media were measured.

RESULTS

At all levels of measurement (origin, 10 cm, and 15 cm), the luminal diameter of the inferior epigastric artery was significantly smaller than that of the right gastroepiploic artery (p < 0.05). The right gastroepiploic artery demonstrated only mild intimal hyperplasia. In contrast, the inferior epigastric artery showed substantial intimal hyperplasia within the first 1-cm segment (mean, 134 +/- 131 microns versus 50 +/- 49 microns for the corresponding segment of the right gastroepiploic artery; p = 0.01). Intimal hyperplasia was only mild in the remainder of the inferior epigastric artery. In both vessels, the media was muscular with rare dispersed elastic fibers. The mean thickness of the media ranged from 380 +/- 116 microns proximally to 155 +/- 70 microns distally for the right gastroepiploic artery, and from 316 +/- 86 to 165 +/- 70 microns, respectively, for the inferior epigastric artery.

CONCLUSIONS

In myocardial revascularization, use of the right gastroepiploic artery may generally be preferable to use of the inferior epigastric artery. This recommendation is based on the larger luminal diameter of the right gastroepiploic artery as compared with the inferior epigastric artery, the significantly greater intimal hyperplasia in the first segment of the inferior epigastric artery, and the limitation that the inferior epigastric artery can be used only as a free graft. The rate of development of intimal hyperplasia in the right gastroepiploic artery, if used as an in situ coronary artery bypass graft, may be slow, approximating that of the right gastroepiploic artery in its natural environment.

Total arterial revascularization of the heart: intentional or inevitable

The impact of left internal mammary to left anterior descending coronary bypass grafting in enhancing long-term patient survival has led to a widespread interest in arterial grafting over the past decade. It is now accepted that the internal mammary artery is a biologically superior coronary bypass graft compared with the traditional saphenous vein. Experience with other arterial grafts--the right gastro-epiploic artery, the inferior epigastric artery and the radial artery--has shown compelling evidence that they share the same biologic advantage. With the judicious use of some or all of these conduits, all regions of the heart can be reached, and total arterial revascularization is a feasible and desirable objective on a routine basis. As long-term results become available, it is inevitable that it will become the operation of choice.