Branch Of Left Internal Mammary Artery Research Articles

Coronary Steal by LIMA Bypass Graft Side-Branches: Physiologic Functional Evaluation and Coil Embolisation

Thoracic side branches of the left internal mammary artery (LIMA) has been reported to cause a coronary steal phenomena if not ligated at the time of surgery. The haemodynamic significance of the unligated side branches remains controversial. We present a case of coronary steal phenomena with an objective evidence of ischaemia that resolved after coil embolisation. A 61-year-old male underwent CABG in 1999 for unstable angina. The LAD received a LIMA graft, vein grafts to the diagonal, obtuse marginal and right coronary artery. His presenting symptom prior to CABG was shortness of breath. He remained symptom free until a year ago where he presented with progressive shortness of breath on minimal exertion despite medical therapy. He underwent a diagnostic coronary angiogram, which revealed severe narrowing in the left main stem, ostial circumflex and proximal LAD as well as occluded right coronary artery. All his grafts were patent. The LIMA was also patent but two unligated thoracic branches were noted. The possibility of coronary steal phenomena was entertained and the patient was brought back to the catheterisation laboratory for fractional flow reserve (FFR) study with a view of coiling the unligated side branches if the FFR was positive. After maximal hyperaemia using intravenous adenosine infusion at 140 mcg/kg/min, maximal FFR was calculated at 0.74 in the distal LAD. Both LIMA branches were occluded with balloons and FFR increased to 0.94. Therefore both branches were coiled and repeat FFR was 0.94 after coil embolisation. Six months later, the patient is off his anti-anginal therapy and is symptom free.

Stem Cells Accumulate on a Decellularized Arterial Xenograft In Vivo

Surgical interest in complete arterial revascularization is expanding, but some patients lack suitable conduits for this goal. The field of stem cell biology is rapidly expanding and, together with the concepts of tissue engineering, offers the promise of growing autologous grafts in the laboratory. We aim to develop a model using human arteries as vascular grafts in a murine model and to assess the cellular accumulation on these grafts. Human arterial samples were collected and decellularized using an ionic detergent. These vessel scaffolds were then used as grafts in an invivo mouse model, and the cellular accumulation on them was examined histologically and by cell culture with assessment of their physiologic properties. Left internal mammary artery branches werefully decellularized and successfully implanted intoa murine model. Grafts were repopulated by cells expressing stem cell markers cluster of differentiation 34 and stage-specific embryonic antigen, and subsequently expressed markers of mature endothelial and smooth muscle cells (cluster of differentiation 31, calponin, and myosin heavy chain). The migratory capacity of the cultured cells was significantly higher than that of mouse smooth muscle cells (p < 0.001). We describe the successful use of human arteries in a murine graft model, allowing the study of repopulation. Decellularized grafts are repopulated by cells expressing stem cell markers and subsequently express smooth muscle and endothelial cell markers. This model has the potential to be used for further development of laboratory-grown vascular grafts.

Extracellular nucleotides induce vasodilatation in human arteries via prostaglandins, nitric oxide and endothelium‐derived hyperpolarising factor

1. The present study was aimed at examining P2 receptor-mediated vasodilatation in human vessels. The isometric tension was recorded in isolated segments of the human left internal mammary artery branches precontracted with 1 microM noradrenaline. 2. Endothelial denudation abolished the dilator responses. 3. The selective P2Y(1) agonist, 2-MeSADP, induced a potent vasodilatation (pEC(50)=6.9+/-0.1). The P2Y(1) antagonist of 10 microM, MRS 2216, shifted the 2-MeSADP concentration-response curve 1.1 log units to the right. The combined P2Y(1) and P2X agonist, 2-MeSATP, stimulated a dilatation with a potency similar to that of 2-MeSADP. Furthermore, MRS 2216 had a similar antagonistic effect on both 2-MeSATP and 2-MeSADP indicating that P2X receptors do not mediate vasodilatation. 4. Both the P2Y(2/4) agonist, UTPgammaS and the P2Y(6) agonist, UDPbetaS, stimulated potent dilatations (pEC(50)=7.8+/-0.4 for UTPgammaS and 8.4+/-0.2 for UDPbetaS). 5. The 2-MeSADP-induced nitric oxide (NO)-mediated dilatation was studied in the presence of 10 micro M indomethacin, 50 nM charybdotoxin and 1 microM apamin. The involvement of the endothelium-derived hyperpolarising factor (EDHF) was investigated in the presence of 0.1 mM L-NOARG and indomethacin. The involvement of prostaglandins was investigated in the presence of L-NOARG, charybdotoxin and apamin. Both NO, EDHF and prostaglandins mediated 2-MeSADP dilatation with similar efficacy (E(max)=25+/-5% for NO, 25+/-6% for EDHF and 27+/-5% for prostaglandins). 6. In conclusion, extracellular nucleotides induce endothelium-derived vasodilatation in human vessels by stimulating P2Y(1), P2Y(2/4) and P2Y(6) receptors, while P2X receptors are not involved. Endothelial P2Y receptors mediate dilatation by release of EDHF, NO and prostaglandins.

Persistence of Mammary Artery Branches and Blood Supply to the Left Anterior Descending Artery

Background. Partial harvesting of the left internal mammary artery (LIMA) is a widespread technique used during minimally invasive coronary operations performed through a left anterior small thoracotomy. The influence of persisting LIMA branches was investigated to evaluate their effect on the blood flow of the left anterior descending artery.Methods. Thirty patients, 15 with totally (group A) and 15 with partially (group B) harvested LIMAs, were evaluated. All the patients underwent postoperative angiography, during which a flow map of the LIMA was performed. The average peak velocity and the diastolic-to-systolic peak velocity ratio were recorded. The LIMA graft flow pattern was recorded in the proximal and distal thirds of the artery. Intramammary adenosine (12 to 14 μg) was injected and the average peak velocities before and after injection were calculated.Results. The average peak velocity was similar in both groups in the proximal and distal thirds of the LIMA (25 ± 7 and 26 ± 5 cm/sec, respectively, in group A versus 27 ± 5 and 25 ± 5 cm/sec, respectively in group B; p = NS). The diastolic-to-systolic peak velocity ratio was similar proximally (0.78 ± 0.3 in group A versus 0.69 ± 0.3 cm/s in group B; p = NS), but not distally (1.72 ± 0.1 in group A versus 0.97 ± 0.3 in group B; p < 0.0005). The LIMA graft flow reserve was similar both proximally and distally (2.6 ± 0.6 and 2.5 ± 0.3 cm/s, respectively, in group A versus 2.6 ± 0.5 and 2.6 ± 0.3 cm/s, respectively, in group B; p = NS).Conclusions. The persistence of LIMA branches does not influence the blood flow of the left anterior descending artery after acute adenosine-induced myocardial hyperemia. If a left anterior small thoracotomy is used in left anterior descending artery direct revascularization, complete LIMA harvesting is not mandatory and depends on the personal preference of the surgeon.(Ann Thorac Surg 1997;63:1759–64)

Myocardial revascularization using branches of the left internal mammary artery.

To increase the number of arterial grafts in patients with multivessel coronary disease, we have used branches of the left internal mammary artery (LIMA) as bypass grafts. From March 1990 to June 1993, 15 patients (13 males and 2 females) aged 38 to 65 years (mean 57 +/- 8), received a total of 30 LIMA branch anastomoses. The two terminal branches were used to perform a "Y" graft to the left anterior descending coronary artery territory in 13 patients. A pericardiophrenic branch was used in four cases. Five patients (33.3%) had complete myocardial revascularization using IMA only. There were neither early nor late deaths and all patients are free from angina at a mean follow-up of 20 months (6 to 45 months). However, early postoperative cardiac catheterization, performed in 12 patients (80%), revealed a 20% occlusion rate for each terminal branch and a 50% occlusion rate for the pericardiophrenic branch. Technically challenging due to the small diameter of the grafts, the terminal LIMA branches should be limited to selected patients when more conventional arterial or vein conduits are not available. More proximal branches have a higher occlusion rate and their use is not recommended.