Left Internal Mammary Artery Flow Research Articles

How to harvest the left internal mammary artery-a randomized controlled trial.

It is uncertain whether Thunderbeat has a place in harvesting the left internal mammary artery (LIMA) and whether skeletonization is superior to pedicle-harvested LIMA. Some investigations have shown improved flowrates in the skeletonized graft. The aim of this study was to compare 3 groups of harvesting techniques: Pedicled, surgical skeletonized and skeletonized with Thunderbeat in terms of flow rates in the LIMA and postoperative in-hospital outcomes. Patients undergoing coronary artery bypass grafting with the LIMA to the anterior descending artery were randomized to pedicled (n = 56), surgical skeletonized (n = 55) and skeletonized with Thunderbeat (n = 54). Main outcomes were blood flow and pulsatility index in the graft. No statistical difference between groups regarding flow in LIMA or pulsatility index. Similarly, no difference in postoperative bleeding or days of hospitalization. The duration of harvesting was faster for the pedicled technique compared with surgical skeletonized and skeletonized with Thunderbeat [mean total min: pedicled 20.2 min standard deviation (SD) ± 5.4; surgical skeletonized 28.6 min SD ± 8.7; skeletonized with Thunderbeat 28.3 min SD ± 9.11, P < 0.001]. No grafts discarded due to faulty harvesting and there was no graft failure within hospital stay. We found no difference between the harvesting methods except for a significantly faster harvesting time with the pedicled technique. However, non-touch skeletonized LIMA harvesting with Thunderbeat seems to be an effective alternative to traditional surgical skeletonized LIMA. The future will reveal whether patency is harvesting dependent. ClinicalTrials.gov Identifier: NCT05562908.

The Value of Left Internal Mammary Artery Flow Velocity in Predicting the Prognosis of Patients After Coronary Artery Bypass Grafting.

The purpose of this study was to explore the value of the left internal mammary artery flow velocity (LIMAV) measured by ultrasound before coronary artery bypass grafting (CABG) in predicting the prognosis of patients after left internal mammary artery (LIMA) bypass grafting. One hundred and four patients who underwent CABG with LIMA as the bridge vessel in the cardiovascular surgery department of our hospital between May 2018 and June 2019 were selected. All patients underwent transthoracic Doppler ultrasonography to measure LIMAV preoperatively. Intraoperatively, mean graft flow (MGF) and pulsatility index (PI) of the LIMA bridge were measured using transit time flow measurement (TTFM). The primary endpoint event in this study was cardiac death within 18 months after surgery. The Cox survival analysis showed that the MGF, the LIMAV and left ventricular ejection fraction (LVEF) were risk factors for death after CABG. The cut-offs of MGF, LIMAV and LVEF for the prediction of death after CABG were ≤ 14 mL/min (area under the curve (AUC): 0.830; sensitivity: 100%; specificity: 65.6%), ≤ 60 cm/s (AUC: 0.759; sensitivity: 65.5%; specificity: 85.3%), and ≤ 44% (AUC: 0.724; sensitivity: 50%; specificity: 88.5%), respectively. Compared with the use of MGF, MGF + LIMAV, combination of the MGF + LIMAV + LVEF (AUC: 0.929; sensitivity: 100%; specificity: 81.1%) resulted in a stronger predictive value (MGF vs. MGF + LIMAV + LVEF: P = 0.02). LIMAV measured by preoperative transthoracic ultrasound combined with intraoperative MGF and LVEF may have a greater value in predicting patients' risk of cardiac death after CABG.

Evaluation of anastomosis quality with intraoperative transit time flowmeter in minimally invasive multi-vessel coronary artery bypass grafting via left anterior mini-thoracotomy.

In this study, we aimed to describe our intraoperative transit-time flow measurement results as an integral component of the operation and evaluate the graft patency and anastomosis quality in patients who underwent minimally invasive multi-vessel coronary artery bypass grafting via mini-thoracotomy. Between May 2020 and September 2021, a total of 45 consecutive patients (32 males, 13 females; mean age: 51.2±8.6 years; range, 41 to 72 years) who underwent minimally invasive multi-vessel coronary artery bypass grafting via left anterior mini-thoracotomy were retrospectively analyzed. We used the technique of intraoperative transit-time flowmetry in all patients. The patients were operated under cardiopulmonary bypass. A saphenous vein graft was used in all anastomoses, except for the left internal thoracic artery. The mean left internal mammary artery flow rate was 36.2±14.1 mL/min, mean flow rate of the diagonal grafts was 48.2±13.1 mL/min, mean flow rate of the circumflex grafts was 41.2±21.1 mL/min, and mean flow rate of the right coronary artery grafts was 52.2±11.3 mL/min. Wave patterns and flow parameters of all grafts were normal in the intraoperative measurements, since the pulsatility index values in all anastomoses were within normal limits. The operation was completed after anastomotic openings and graft patency were ensured. The use of an intraoperative flowmeter to show the graft patency and anastomosis quality gives confidence both to the surgeon and the patient. In multi-vessel coronary artery bypass grafting via mini-thoracotomy, anastomosis quality can be evaluated well with this technique.

LIMA Serbestleştirilmesi İçin Papaverinin Ultrason Kılavuzluğunda Transvers Torasik Kas Düzlemine Enjeksiyonu ile Topikal Uygulamasının Karşılaştırılması: Bir Pilot Çalışma

INTRODUCTION: Although the effect of topical papaverine on the left internal mammary artery (LIMA) flow is a well-known method, papaverine hydro dissection is applied to the transverse thoracic muscle plane is unknown. This study aims to investigate the effect of ultrasound-guided transverse thoracic muscle plane papaverine injection on LIMA flow. METHODS: ASA II-III, 40 patients who underwent coronary artery bypass grafting surgery, were randomly divided into two groups. Group topical papaverine (Group TP, n=20) and Group ultrasound-guided papaverine (Group USP, n=20). In Group TP, 10 mg papaverine in 10 mL saline was administered topically after LIMA harvesting. In Group USP, ultrasound-guided transverse thoracic muscle plane papaverine injection with the same solution preoperatively. Trans-time flow measurements (TTFM), LIMA harvesting time, and surgeon satisfaction were recorded. RESULTS: There was no difference in LIMA free flows before anastomosis between Group USP and Group TP (111.35±69.76 vs. 92.15±46.76, respectively, p=0.185). There was no significant difference between the groups in TTFM values evaluated after anastomosis (p&gt; 0.05). LIMA harvesting time was statistically shorter in Group USP than Group TP (13.90±3.01 vs. 16.65±4.50 respectively, p=0.049). Surgeon LIMA harvest satisfaction was statistically significantly higher in group USP (p=0.029). DISCUSSION AND CONCLUSION: We think that papaverine injection via ultrasound-guided transverse thoracic muscle plane may be an alternative method to topical application to prevent LIMA spasm.

Blood flow assessment by transit time flow measurement and its prognostic impact in coronary bypass surgery.

The competitive coronary flow is influenced by the severity of the stenosis and may affect graft patency. Transit time flow measurement (TTFM) enables intraoperative graft evaluation and cardiac magnetic resonance (MRI) allows for graft evaluation during follow-up. Competitive flow and target vessel diameters were determined in 35 patients undergoing off-pump coronary bypass graft surgery (CABG) and correlated to TTFM. Cardiac function, ischemia, and graft flow were evaluated using cardiac MRI during the follow-up period to determine the impact of above-mentioned parameters on graft patency. Competitive flow led to reduced mean graft flow (MGF) and increased pulsatility index (PI) in arterial grafts. This effect to was not observed in veins. Smaller target coronary arteries (<1.5 mm) were associated with reduced MGF, more pronounced in veins, which presented increased PI and shortened diastolic flow fraction (DF). No death and no re-hospitalization for acute coronary syndrome occurred. Borderline values of TTFM (mean MGF 13±4 mL/min; PI 3.8±1) in left internal mammary artery (LIMA) were mainly observed due to increased native anterior descending artery (LAD) flow. These LAD's collateralized occluded right coronaries (RCA). The corresponding LIMA to LAD grafts showed a bypass flow increase at cardiac MRI follow-up. Two graft occlusions occurred: one in LIMA-to-LAD bypass with borderline TTFM, which did not collateralize the RCA and one in a vein graft with borderline TTFM bypassed on a narrow vascular target. Competitive flow has an impact on arteries contrary to veins. Veins are at risk for occlusion when grafted to smaller targets. Borderline LIMA flow should be considered as potentially dangerous, if satisfactory explanations are missing, e.g. in the absence of a large coronary target without flow competition.

Effect of Papaverine on Left Internal Mammary Artery Flow: Topical Spraying versus Perivascular Injection Method.

ObjectiveTo analyze two techniques of papaverine application, topical spray on the harvested left internal mammary artery (LIMA) and perivascular injection, to find out their ability to improve LIMA flow.MethodsForty patients were randomized into two groups. In Group 1, papaverine was sprayed on the harvested pedunculated LIMA. In Group 2, papaverine was delivered into the perivascular plane. Drug dosage was the same for both groups. LIMA flow was measured 20 minutes after applying papaverine. Blood flow was recorded for 20 seconds and flow per minute was calculated. The systemic mean pressures were maintained at 70 mmHg during blood collection. The data collected was statistically evaluated and interpreted.ResultsThe LIMA blood flow before papaverine application in the Group 1 was 51.9±13.40 ml/min and in Group 2 it was 55.1±15.70 ml/min. Statistically, LIMA flows were identical in both groups before papaverine application. The LIMA blood flow, post papaverine application, in Group 1 was 87.20±13.46 ml/min and in Group 2 it was 104.7±20.19 ml/min. The Group 2 flows were statistically higher than Group 1 flows.ConclusionPapaverine delivery to LIMA by the perivascular injection method provided statistically significant higher flows when compared to the topical spray method. Hence, the perivascular delivery of papaverine is more efficient than the spray method in improving LIMA blood flow.

Intraoperative Bypass Graft Flow Measurement With Transit Time Flowmetry: A Clinical Assessment

Guidelines advocate transit time flowmetry (TTFM) for intraoperative graft patency verification during coronary artery bypass graft surgery (CABG), but studies on accuracy and precision of the TTFM technique are few. In an observational study of CABG patients, we analyzed covariation of left internal mammary artery (LIMA) blood flow with TTFM and free flow measurements. Covariation of TTFM and free blood flows was evaluated in 60 patients undergoing CABG using the LIMA as one of the conduits. With LIMA flow measurements routinely performed before and after vasodilation, results are based on 120 paired intraoperative measurements. As demonstrated by a combined approach of regression and Bland-Altman analysis for the two flow situations, TTFM was higher than free flow in 64% of measurements, with an overestimation by TTFM of 7.1% ± 16.3% in the overall cohort (prevasodilation), statistically carried by measurements with 4-mm probes (overestimation by 13.3% ± 15.4%, both p < 0.01). In a multiregression analysis, oversizing of the TTFM probe (odds ratio 9.56, 95% confidence interval: 2.03 to 45.10, p= 0.004) and high flows (odds ratio 1.02, 95% confidence interval: 1.01 to 1.04, p < 0.001) were independent determinants of flow overestimation by TTFM, although in the Bland-Altman analysis no systematic overestimation was seen in the postvasodilation situation. In a receiver-operating characteristics analysis, optimal cutoff value as determined from Youden's index for assuming flow overestimation was 68 mL/min. Overall, with slight overall overestimation of 7.1%, TTFM is an accurate indicator of LIMA blood flow during CABG, with a clinically acceptable precision. Overestimation may be expected with flows greater than 68 mL/min, but most importantly, in situations with oversized TTFM probes.

Coronary artery steal syndrome in patient after coronary arteries by-pass surgery and left subclavian artery stenting-is the maintenance of a patent internal mammary artery still necessary?

The use of the left internal mammary artery (LIMA) is preferred for the revascularization of a stenosed or occluded left anterior descending artery (LAD). Occlusion or stenosis of proximal part of the left subclavian artery (LSA) could induce reverse blood flow in LIMA called coronary subclavian steal syndrome (CSSS) and should be revascularized before coronary artery bypass grafting (CABG) surgery with LIMA. If restenosis of previously stented LSA occurs after CABG surgery with LIMA another revascularization is inevitable. However, the revascularization of LSA could reveal that increased blood pressure in LAD persistent through years due to present CSSS could substantially influence blood pressure change in coronary arteries and LIMA graft. This phenomenon can raise the question if it is necessary to maintain patent LIMA-LAD graft.

GRAFT PATENCY OF AN ALTERNATIVE CORONARY BYPASS GRAFTING TECHNIQUE: THE SAPHENOUS VEIN BRIDGE - COHORT STUDY

GRAFT PATENCY OF AN ALTERNATIVE CORONARY BYPASS GRAFTING TECHNIQUE: THE SAPHENOUS VEIN BRIDGE - COHORT STUDY

Continuous Monitoring of Regional Function by a Miniaturized Ultrasound Transducer Allows Early Quantification of Low-Grade Myocardial Ischemia

Sensitive methods for the early detection of myocardial dysfunction are still needed, as ischemia is a leading cause of decreased ventricular function during and after heart surgery. The aim of this study was to test the hypothesis that low-grade ischemia could be detected quantitatively by a miniaturized epicardial ultrasound transducer (Ø = 3 mm), allowing continuous monitoring. In 10 pigs, transducers were positioned in the left anterior descending and circumflex coronary artery areas. Left ventricular pressure was obtained by a micromanometer. The left internal mammary artery was grafted to the left anterior descending coronary artery, which was occluded proximal to the anastomosis. Left internal mammary artery flow was stepwise reduced by 25%, 50%, and 75% for 18 min each. From the transducers, M-mode traces were obtained, allowing continuous tissue velocity traces and displacement measurements. Regional work was assessed as left ventricular pressure-displacement loop area. Tissue lactate measured from intramyocardial microdialysis was used as reference method to detect ischemia. All steps of coronary flow reduction demonstrated reduced peak systolic velocity (P < .05) and regional work (P < .01).The decreases in peak systolic velocity and regional work were closely related to the degree of ischemia, demonstrated by their correlations with lactate (R = -0.74, P < .01, and R = -0.64, P < .01, respectively). The circumflex coronary artery area was not affected by any of the interventions. The epicardially attached miniaturized ultrasound transducer allowed the precise detection of different levels of coronary flow reduction. The results also showed a quantitative and linear relationship among coronary flow, ischemia, and myocardial function. Thus, the ultrasound transducer has the potential to improve the monitoring of myocardial ischemia and to detect graft failure during and after heart surgery.

Composite versus conventional coronary artery bypass grafting strategy for the anterolateral territory: study protocol for a randomized controlled trial

BackgroundIn severe coronary artery disease, coronary artery bypass grafting (CABG) surgery is indicated to re-establish an adequate blood supply to the ischemic myocardium. Effectiveness of CABG surgery for symptom relief and mortality decrease should therefore depend on bypass graft patency. As bypass using a left internal mammary artery (LIMA)-to-left anterior descending coronary artery (LAD) anastomosis allows the best results in terms of graft patency, we designed a new surgical technique using a saphenous vein graft as a venous bridge to distribute the LIMA flow to the cardiac anterolateral territory. This novel strategy could extend the patency benefits associated to the LIMA. Other potential benefits of this technique include easier surgical technique, possibility to use saphenous vein grafts as vein patch angioplasty, shorter saphenous vein grafts requirement and reduced or eliminated manipulations of the ascendant aorta (and associated stroke risk).Methods/DesignBetween July 2012 and 2016, 200 patients undergoing a primary isolated CABG surgery using cardiopulmonary bypass with a LAD bypass graft and at least another target on the anterolateral territory will be randomized (1:1) according to 1) the new composite strategy and 2) the conventional strategy with a LIMA-to-LAD anastomosis and revascularization of the other anterolateral target(s) with a separated aorto-coronary saphenous vein graft. The primary objective of the trial is to assess whether the composite strategy allows non-inferior anterolateral graft patency index (proportion of non-occluded CABGs out of the total number of CABGs) compared to the conventional technique. The primary outcome is the anterolateral graft patency index, evaluated at one year by 256-slice computed tomography angiography. Ten years of clinical follow-up is planned to assess clinical outcomes including death, myocardial infarction and need for revascularization.DiscussionThis non-inferiority trial has the potential to advance the adult cardiac surgery field, given the potential benefits associated with the composite grafting strategy.Trial registrationClinicalTrials.gov: NCT01585285.

Competitive flow arising from varying degrees of coronary artery stenosis affects the blood flow and the production of nitric oxide and endothelin in the internal mammary artery graft

Internal mammary arteries graft failure in coronary artery bypass grafting (CABG) is mostly considered to be a result of competitive flow (CF) from the native coronary artery, which significantly limits future revascularization options. With the left internal mammary artery (LIMA) anastomosed to the left anterior descending (LAD) coronary artery using an off-pump technique, CABG was performed on 15 Chinese swine. Then we produced varying degrees of stenosis in the proximal LAD coronary artery with an adjustable flow occluder, measured the mean flow of the LIMA and LAD coronary artery and detected the plasma concentrations of nitric oxide (NO) and endothelin (ET) in the LIMA graft. When stenosis of the proximal LAD artery was decreased, the CF of the native LAD coronary artery showed an increasing trend, while the mean flow of the LIMA revealed a decreasing trend. Distal LAD coronary artery flow remained nearly constant, despite the varying proximal LAD artery or LIMA flow rates. An oscillating flow pattern (retrograde/antegrade) was noted in the LIMA graft when the proximal LAD coronary artery was not fully occluded. The plasma concentration of ET in the LIMA graft was significantly higher than that before grafting (P < 0.05), and the plasma concentration of NO was significantly lower (P < 0.05). The concentration of NO was positively related to the mean flow in the LIMA (r = 0.872, P < 0.05). CF from the native LAD coronary artery can decrease the blood flow in the LIMA graft and even change the direction of the flow. These changes may impair the function of the LIMA graft and affect ET or NO production, which in turn may lead to early LIMA graft failure.

EComment. Extended sternal retraction and internal mammarian artery flow

We read with interest the manuscript by Espinoza et al. [1], in which the authors presented two patients in whom internal mammary artery (IMA) flow was compromised with extended sternal retraction during off-pump coronary artery bypass grafting (CABG). We would like to comment on the authors' paper with similar incidents that we have encountered in our practice. We had 3 patients in whom the left IMA flow was decreased when we widely opened the sternum retractor during CABG. The first patient had cerebrovascular disease (left vertebral artery occlusion and insignificant left internal carotid artery stenosis) in addition to coronary lesions. We detected an accessory ascending collateral branch from the IMA after careful exploration of the proximal part of the artery. Flow reduction was overcome with clipping of this vessel and freeing of the IMA. The procedure did not affect the neurological status of the patient in the postoperative period. In the second patient, the IMA divided into two branches after the middle segment, measuring 1 mm in diameter. Left anterior descending artery was bypassed with the suitable middle portion of the IMA. Sternal over-retraction caused flow reduction, which was overcome with the approximation of the sternal edges. In both patients, we proposed that the reason for the reduction in the flow of IMA was due to distention of the graft. In the third patient, there was no identifiable cause for the decrease in IMA flow, other than sternal retraction. Since IMA was the last anastomosed graft before the proximal anastomosis in our procedures, decrease in IMA flow was detected with simple palpation of the vessel and managed accordingly. IMA is still the gold standard graft for myocardial revascularization. We believe, it should be kept in mind that there may be various reasons which may lead to compromised IMA flow, either of the most common distention or sometimes of an idiopathic nature. Although flow compromise may be evaluated by transit-time flow measurement, simple palpation of the graft is also simple and effective method. Conflict of Interest: None declared

Effect of graft adaptation of the internal mammary artery on longitudinal phasic blood flow velocity characteristics after surgery

Left internal mammary artery (LIMA) bypass conduits undergo gradual longitudinal flow transition from the proximal to distal segments, and the diastolic/systolic (D/S) ratios of the flow indices can diagnose graft patency. However, the influence of graft adaptation on this has not been studied. We examined 46 patients with LIMA graft to the left anterior descending artery using a Doppler-tipped guidewire in the proximal, middle, and distal segments; 34 had patent LIMAs (group A: new LIMAs; <1month postoperatively; n=22 and group B: old LIMAs; ≥1month postoperatively; n=12), and 12 had new LIMAs with distal stenosis (group C). In diastole, the time-averaged peak velocities, maximum peak velocities, and velocity-time integrals in each segment were significantly greater in group A than in groups B or C; however, in systole, they did not differ significantly among the three groups. The D/S ratios of the indices in all segments in group A were significantly greater than those in groups B or C; however, they did not differ between groups B and C in any of the segments. Graft adaptation of a patent LIMA, itself, affects the longitudinal flow transition pattern. The D/S ratio of the three indices in the patent old LIMAs did not differ from those in the LIMAs with distal stenosis early after surgery. The timing of LIMA flow assessment must be considered during assessment of the graft patency from the flow velocity patterns.

Massive Coronary Subclavian Steal Syndrome

Coronary subclavian steal syndrome is an unusual cause of angina, secondary to decreased or reversed flow in patients with patent "in situ" internal mammary-to-coronary artery graft. The most frequent cause of coronary subclavian steal syndrome is ipsilateral subclavian artery stenosis. We present a 60-year-old man with cerebrovascular and peripheral artery disease and a documented massive coronary subclavian steal syndrome, which impaired cardiopulmonary bypass weaning after multiple coronary artery bypass with double T-mammary artery graft.

Non-invasive diagnosis of coronary-subclavian steal: role of the Doppler ultrasound

Coronary subclavian steal syndrome (CSSS) is a well documented cause of graft function failure in patients after left internal mammary artery (LIMA)--left anterior descending (LAD) coronary artery grafting. We present a case of the CSSS in a patient with cardiac arrest due to ventricular fibrillation. To our knowledge such a case has not yet been described. Patient with a history of LIMA-LAD grafting, complaining only of a mild chronic exertional dyspnoea developed ventricular fibrillation while walking outdoor. After successful resuscitation, blood pressure difference between both arms and abnormal LIMA flow with systolic reversal flow on the Doppler ultrasonography were suggestive of CSSS. Angiography proved the left subclavian artery (LSA) occlusion and coronary angiography confirmed reversal flow in the LIMA graft. Successful percutaneous transluminal angioplasty of the LSA re-established normal LIMA flow and improved the left ventricular hypokinesis and systolic function.

Late thrombotic occlusion of a left internal mammary artery graft causing ST-elevation myocardial infarction

Late occlusion of the left internal mammary artery (LIMA) is rare, and its pathological basis is unknown. We present a case of acute occlusion of the LIMA in a 77-year-old woman, 7 years after graft surgery, causing fatal myocardial infarction. Diagnostic angiography of the LIMA revealed a proximal occlusion just beyond the LIMA origin which re-canalised after repeated injection of contrast with near complete restoration of LIMA patency and flow with smooth angiographic appearance. Despite initial diminution of pain and electrocardiographic changes with recanalisation, pain and ST changes returned and the patient died. Restoration of near normal vessel patency with angiography suggests that the basis of this occlusion is not atherosclerotic plaque rupture, but is more likely to represent in situ thrombosis or, less likely, localized spasm. Early recognition of the possibility of LIMA occlusion may direct initial angiography to the LIMA rather than the native circulation, and reduce the time to reperfusion.

Selective Retrograde Venous Revascularization of the Myocardium when PCI or CABG Is Impossible: Investigation in a Porcine Model

We investigated the possibility of nourishing the myocardium through selective retrograde coronary venous bypass grafting (CVBG) with an off-pump technique and evaluated various methods of monitoring the physiological effects of this procedure. In a porcine model, the left internal mammary artery (LIMA) was anastomosed to the left anterior descending coronary vein (LAD vein) in an off-pump procedure. The LAD vein was ligated proximal to the anastomosis. The LAD artery was ligated proximally. The physiological effects were monitored using microdialysis, tissue oxygen tension, blood flow in LIMA, blood samples, and hemodynamic and histological analyses. As controls, 5 pigs underwent surgery involving only LAD artery ligation without CVBG. CVBG with LAD ligation was performed in 16 pigs; 12 survived CVBG and were monitored for 2-2.5 hours while in sinus rhythm, a 75% salvage rate after an otherwise lethal LAD artery occlusion. Immediately after LAD artery ligation, the anterior wall of the left ventricle became cyanotic and hypokinetic. Over time it regained color and contractility as flow in the LIMA increased. Microdialysis showed a significant increase in lactate. Initially tissue oxygen tension decreased, but with time some recovery was seen. Cardiac troponin T was elevated. Histological analysis showed ischemic changes. In control pigs, microdialysis was performed for 1.5 hours up to LAD artery ligation, after which all pigs died in ventricular fibrillation arrest. No increase in lactate was observed. These results indicate that after LAD artery occlusion, CVBG can nourish the myocardium to a certain extent and prevent death in the majority of cases, although varying degrees of ischemia remain.

TRANSOESOPHAGEAL ECHOCARDIOGRAPHIC EVALUATION OF INTERNAL MAMMARY ARTERY FLOW PRE- AND POST-CORONARY ARTERY GRAFTING

Introduction. Imaging of the left internal mammary artery (LIMA) using a transoesophageal echocardiographic (TOE) approach was first described by Nanda et al. in 1999. 1 Nanda N.C. Thakur A.C. Thakur D. Narayan V.K. Espinal M.A. Shoeb G. Samal A.K. Voros S. Aaluri S.R. Ocak O. John A.S. Pasia A.T. Aikens M. Transesophageal echocardiographic examination of left subclavian artery branches. Echocardiography. 1999; 16: 271-277 Crossref PubMed Scopus (16) Google Scholar However, the technique has attracted little interest despite the increasing use of this form of monitoring in patients undergoing coronary artery bypass grafting (CABG). In this study we examined the feasibility of using TOE to evaluate LIMA flow during the course of CABG to the left anterior descending artery (LAD). By measuring the changes in flow characteristics pre- and post-grafting we hoped to demonstrate the extent of competitive flow in the LIMA/LAD system.

Perioperative monitoring of flow and patency in native and grafted internal mammary arteries using a combined MR protocol

The objective of this study was to evaluate graft flow (f) and patency (p) in patients with internal mammary artery (f,p) and venous (p only) grafts using a combined MR protocol with phase-contrast technique and MR angiography. 42 patients with 42 left internal mammary artery (LIMA) and 63 venous grafts were examined pre and 6 months post coronary artery bypass graft (CABG) surgery. Phase-contrast flow measurements were applied to the IMA. Post-operatively, a contrast enhanced MR angiogram was performed to assess bypass patency. LIMA/venous grafts were occluded in 3/42 and 13/63, respectively. Flow in LIMA decreased from 19.4+/-10.4 ml min(-1) m(-2) pre-operatively to 13.4+/-9.7 ml min(-1) m(-2) post-operatively (p<0.002). In contrast, flow in the native right IMA increased from 17.6+/-8.7 ml min(-1) m(-2) pre-operatively to 24.8+/-9.0 ml min(-1) m(-2) post-operatively (p<0.001). MRI allows a combined assessment of bypass patency and flow. This study protocol may be applicable to perioperative follow-up studies in patients after CABG surgery.