Internal Thoracic Research Articles

Abstract 2050: Differential Effects of Natriuretic Peptides on Arterial and Venous Coronary Artery Bypass Conduits

Background: Long-term patency of arterial grafts used for coronary bypass grafting (CABG) is superior to that of venous grafts. Natriuretic peptides (NP’s) have a major role in vascular homeostasis. We characterized the effects of NP’s and their receptors (NPR) in commonly used CABG conduits. Methods: The relaxation and tissue levels of cGMP in response to 3 NP’s (ANP, BNP and CNP) were assessed in pre-contracted segments of internal mammary artery (IMA), radial artery (RA) and saphenous vein (SV) obtained from the same patients (n=12) in the absence/presence of the LY83583 (Guanylyl Cyclase inhibitor) or L-NAME (Nitric Oxide synthase inhibitor). NPR expression was assessed using immunohistochemistry and Western blotting. Results: Results are summarized in the Tables . Maximal relaxation of the IMA and RA to ANP, BNP and CNP were similar and greater than SV, correlating with increased tissue levels of cAMP in both arterial conduits. Relaxation response to all 3 NP’s were nearly abolished in the presence of LY83583. Exposure of the conduits to L-NAME resulted in only a modest blunting of the relaxation response to the NP’s. NPR-A, NPR-B and NPR-C were strongly expressed in both the endolethium and vascular smooth muscle layer of the IMA and RA and significantly less in SV. Conclusion: NP’s are potent vasodilators of the IMA and RA but not the SV. The relaxation response is mediated via NPRs/cGMP and the Nitric Oxide systems. These observations provide additional insight into the potential physiological mechanisms underlying the superior patency of arterial conduits and may form a basis for potential therapeutic interventions aimed to improve vein grafts performance. Vessel Relaxation Response to NP’s Tissue cGMP levels in response to NP’s and NPR Protein Expression

Total Arterial Revascularization and Concomitant Aortic Valve Replacement

The safety of total arterial revascularization with a left internal thoracic artery-radial artery T-graft was evaluated in patients with at least two-vessel coronary artery disease and aortic valve stenosis requiring concomitant aortic valve replacement. From June 2001 to January 2005, 18 patients underwent aortic valve replacement and total arterial revascularization, while 101 had aortic valve replacement and conventional grafting. By matching age, sex, left ventricular ejection fraction, and number of distal anastomoses, 1:2 matched groups were generated: 15 patients with a left internal thoracic-radial artery T-graft, and 30 with left internal thoracic artery and additional vein grafts. Aortic cross clamp and cardiopulmonary bypass times were similar in both groups. There were no significant differences in postoperative data between the groups. Early mortality was 0% in the T-graft group and 2% in those with conventional grafts. Follow-up ranged from 2 to 50 months. Event-free survival was 100% in the T-graft group and 90% in the conventional graft group. Total arterial grafting with a left internal thoracic-radial artery T-graft can be performed in selected patients with aortic valve stenosis requiring simultaneous aortic valve replacement.

Short presentation of DIEP and SIEA flaps

The adipocutaneous tissue from the lower abdomen remains the most commonly used donor site in autologous breast reconstruction following mastectomy. There is current trend from conventional TRAM free flap toward perforator and muscle sparing flaps use. DIEP free flap preserves the rectus abdominis muscle but nevertheless demands dissection of the pedicle and thus at least some violation of the abdominal wall muscle integrity. This can in turn weaken the abdominal wall although in much smaller extent than conventional TRAM flap harvest. For this reason we always examine the presence of the superficial epigastric system first and hence start harvesting the flap in suprapubic and ingvinal region. When substantial pedicle is located (˜20%), flap is raised based on superficial system and abdominal wall is left intact. When superficial vessels are absent or not reliable we base the flap on deep epigastric vessels system as DIEP or MS TRAM. In either case there is no need for foreign material insertion to strengthen the rectus sheath defect. The flap vessels are usually anastomosed to internal mammary artery and vein. The access to recipient vessels is accomplished by removing the 3rd or 4th rib cartilage at the site of mastectomy (alternative thoracodorsal). Flap is tailored, partially de-epithelialised and positioned in the mastectomy defect. Viability of the transferred tissue is monitored continuously. The manner of how we harvest the flap from the donor area is of utmost importance for the abdominal wall integrity and of a less significant for the result of breast reconstruction per se. Advantages of harvesting various flaps from the same donor site (abdomen) will be discussed and illustrated with cases.

Atherosclerosis of Radial and Internal Thoracic Arteries Used in Coronary Bypass: Atherosclerosis in Arterial Grafts

This study aimed to evaluate the degree and incidence of atherosclerosis in internal thoracic (ITA) and radial arteries (RA) harvested for coronary bypass grafting. The association of major clinical events and etiological factors for atherosclerosis was investigated in 770 arterial segments obtained prospectively from 480 patients. Potential risk factors for atherosclerosis were age, gender, smoking, diabetes mellitus, peripheral vascular disease, cerebrovascular disease, chronic renal failure, hypercholesterolemia, obesity, hypertension, and a positive family history. Six types of histological lesions have been defined; grade III or more was present in the RA in 47 (16%) patients and in the ITA in 30 (7%). The mean grade was 1.6 +/- 0.6 in the ITA and 2.1 +/- 0.9 in the RA (p < 0.001). RA had a significantly greater prevalence of atherosclerosis than the same patients' ITA. There was a strong correlation between ITA atherosclerosis and age. The presence of calcification may lead surgeons to avoid an extra incision according to risk factors, although most of these are not predictive.

Using Microvascular Anastomotic Coupler System for Venous Anastomosis of Internal Mammary Vein in Breast Reconstruction

Microsurgery replacing like tissue with like tissue from a distant site has revolutionized the strategy of reconstruction. The microvascular venous anastomosis remains one of the most challenges for breast reconstruction using internal mammary vessels as the recipient site. The objective of this study was to study the outcome of using Microvascular Anastomotic Coupler (MAC) System for venous anastomosis of internal mammary vein (IMV) in breast reconstruction. Between March of 2003 and December of 2005 seven deep inferior epigastric perforator (DIEP) flaps with the IMV as the recipient sites were used for breast reconstruction. Five flaps (71.4%) were in delayed reconstructions and two flaps (28.6%) in immediate recosntructions. Six reconstructions were for the treatment of post mastectomy breast defect and one was for resurfacing of post- burn scar contracture. The venous anastomoses were performed using the MAC in the 7 reconstructions. All the venous anastomoses were patent, giving a 100% success rate. None of the patients manifested any peri-operative complication or long-term foreign body reaction. The MAC has the advantages of relative easy use, time saving and less technique demand. The MAC is a reliable technique with high patency rate and low complication rate. It is advised to use in venous anastomosis of internal mammary vein for breast reconstruction.

Focal Hepatic Activity During Ventilation-Perfusion Scintigraphy Due to Systemic-Portal Shunt Due to Superior Vena Cava Obstruction From Histoplasmosis-Induced Fibrosing Mediastinitis

A 59-year-old woman with a history of fibrosing mediastinitis secondary to histoplasmosis diagnosed on mediastinoscopy presented with dyspnea. A ventilation-perfusion scan demonstrated decreased perfusion to the entire right lung. In addition, the perfusion images demonstrated focal abnormal activity in part of the liver. On computed tomography of the chest, there was significant soft tissue opacification in the mediastinum occluding the right pulmonary artery, with passage of the injected contrast via collateral vessels to the liver. The main collateral pathway was via the right internal thoracic vein and the umbilical vein. Pulmonary angiography confirmed complete occlusion of the right pulmonary artery.

Tunneled Central Venous Catheter Malpositioning

Laureys and Rommens have recently described their experience with the spontaneous repositioning of a tunneled central venous catheter post injection of contrast medium [1]. We would like to add an experience we had with the malpositioning of a catheter and describe a further means of avoiding this complication. The authors described catheter misplacement in the right internal mammary vein and reported an overall catheter mislocation incidence of 0% to 4% [2]. They felt that conventional anteroposterior (AP) fluoroscopy (as recommended for checking correct position) would not have avoided incorrect positioning in this case. The authors have now changed their practice and inject hypo-osmolar contrast medium to ensure correct catheter placement. At our institution we have had similar experience with catheter malposition in the azygos system, also appearing correctly placed on AP fluoroscopy. We have subsequently modified our practice to ensure correct catheter placement by initial guidewire manipulation through the right atrium and down the inferior vena cava (IVC) to its bifurcation. We believe that if the guidewire can be advanced with ease to this position, it can only be in the IVC, thus ensuring appropriate proximal catheter placement without the need for iodinated contrast medium injection. Since adoption of this technique at our institution we have had no incidence of catheter misplacement, and furthermore, complicated venous anatomy is identified at an early stage of the procedure at which stage contrast venography can be performed if required. In conclusion, we agree that systematic injection of hypo-osmolar contrast medium is a more reliable method of ensuring correct catheter placement than simply relying on AP fluoroscopy. However, we feel that the simple technique of initial guidewire manipulation into the distal IVC ensures proper proximal catheter placement without the utilization of iodinated contrast medium.

Engineering blood vessels by gene and cell therapy

Cardiovascular-related syndromes are the leading cause of morbidity and mortality worldwide. Arterial narrowing and blockage due to atherosclerosis cause reduced blood flow to the brain, heart and legs. Bypass surgery to improve blood flow to the heart and legs in these patients is performed in hundreds of thousands of patients every year. Autologous grafts, such as the internal thoracic artery and saphenous vein, are used in most patients, but in a significant number of patients such grafts are not available and synthetic grafts are used. Synthetic grafts have higher failure rates than autologous grafts due to thrombosis and scar formation within graft lumen. Cell and gene therapy combined with tissue engineering hold a great promise to provide grafts that will be biocompatible and durable. This review describes the field of vascular grafts in the context of tissue engineering using cell and gene therapies.

Arm temperature distribution in thermographic pictures after radial artery harvesting for coronary bypass operation

The radial artery (RA) beside the left internal mammary artery and veins is often used for coronary artery bypass grafting. The aim of this study was to assess arm temperature changes after removal of the radial artery and determine whether there is an effect on hand function. Between April and December 2005, fifty patients underwent myocardial revascularization employing the pedicle RA as one of the coronary grafts. The study protocol included thermographic and clinical examination one day before the surgery and on the sixth day after the procedure. An Agema 900 Thermovision System was used for thermographic evaluation. Thermovision examinations were carried out at rest and after a handgrip test before and after radial artery harvesting. Temperature was measured on each finger and on the forearm (separately on the radial and ulnar side of the forearm). All examinations were performed in the same conditions. Hand endurance was compared with the 2 min handgrip test before and after the surgery. A comparison of hand temperature changes during the handgrip test before and after radial artery harvesting showed no significant difference (P>0.05). Before the surgery a significant increase in temperature over the ulnar artery was observed after the handgrip test. There were no clinical symptoms of acute or subacute hand ischemia. No clinical evidence of hand claudication was detected. There was no significant difference in hand endurance after radial artery harvesting. This study suggests that removal of the radial artery changes the hand temperature distribution but does not affect hand function in the short-term. In the study group, radial artery harvesting did not cause clinically relevant changes in blood support of the arm.

Arterial coronary–coronary conduit over single, distal left anterior descending coronary artery lesion: 3.5 years afterward

Arterial coronary–coronary conduit over single, distal left anterior descending coronary artery lesion: 3.5 years afterward

Use of the Internal Mammary Vein for Access Outflow in a Hemodialysis Fistula

A patient with occlusion of multiple central veins from both dialysis and nondialysis catheters required permanent access for hemodialysis. Magnetic resonance imaging showed a patent left innominate vein. He underwent creation of a left axillary artery to internal mammary vein transposition fistula using the basilic vein from his right arm. The fistula has required one revision for outflow stenosis and one for aneurysmal degeneration. It continues to function well 3 years after placement. The internal mammary vein is an option for outflow when permanent hemodialysis access has failed in the presence of a patent innominate vein with occluded or severely stenotic ipsilateral subclavian and jugular veins.

Concomitant Myocardial Revascularization and Modified Radical Mastectomy: Report of a Case

We report a successful concomitant myocardial revascularization with modified mastectomy on a female octogenarian. This patient had suffered from chest tightness for two years, and was proved to have triple-vessel coronary artery disease (CAD) with significant stenotic lesions on her left anterior descending (LAD) and circumflex coronary artery in addition to total occlusion of her right coronary artery with collateral circulation from the left side coronary artery. She also had a palpable mass in her left breast for one year that was proved to be cancer of the breast later. After evaluation of surgical risk, possible complications and prognosis in a combined conference, our surgical team decided to perform percutaneous transluminal coronary angioplasty (PTCA) for circumflex coronary artery first. Then we performed a concomitant minimally invasive direct coronary artery bypass (MIDCAB) with left internal thoracic artery (ITA) bypassing to LAD and a left modified mastectomy with axillary node dissection at the same time through the same surgical incision. The patient withstood the procedure well and was followed up 24 months later without any evidence of recurrence of chest discomfort or the breast cancer. A combination of myocardial revascularization and modified mastectomy seems to be an alternative strategy for patients with CAD and cancer of the left breast.

Venous Outflow Alternatives in Free Breast Reconstruction

Free tissue transfer has become an accepted and reliable method of breast reconstruction. In most cases, the internal mammary or thoracodorsal vessels are utilized as the standard recipient vessels. The authors reviewed their series of venous outflow alternatives in free breast reconstruction when the internal mammary and thoracododorsal veins were deemed inadequate or unusable.

Inability to start hemodialysis after a smooth temporary hemodialysis catheter insertion procedure

Cannulation of the central vein for placement of the temporary dual-lumen catheter for hemodialysis can usually be safely and reliably performed under ultrasonographic guidance. Here, we report a case of aberrant catheter entry into the internal thoracic vein during an apparently smooth procedure. The value of sonographic guidance, together with fluoroscopy with or without venography, will be discussed.

The cephalic and external jugular veins: Important alternative recipient vessels in left‐sided microvascular breast reconstruction

The internal mammary and thoracodorsal vessels are the standard recipient sites in microsurgical breast reconstruction. We review our series of venous outflow alternatives when these vessels are inadequate or unusable. A retrospective review of all free breast reconstructions was performed from July 2003 through December 2005. Outcomes were measured with regard to re-exploration, flap failure, and fat necrosis, with attention to the timing and side of reconstruction, as well as the presence or absence of radiation therapy. A total of 141 free breast reconstructions were performed during the study period. In seven cases (5%), alternative venous outflow vessels were selected (cephalic or external jugular vein). Nine anastamotic complications occurred, all of which involved the left internal mammary group (statistically significant for venous thrombosis, P = 0.0063) and three flaps failed. All cephalic and external jugular veins remained patent with no flap failures or fat necrosis within this group. The cephalic vein and external jugular vein are excellent alternatives for venous outflow in free breast reconstruction if neither the internal mammary nor thoracodorsal veins are sufficient, especially in left-sided reconstruction.

Differential mechanisms of nitric oxide and cyclooxygenases in endothelium‐dependent relaxation of human internal mammary artery and saphenous vein as bypass grafts

Differential mechanisms of nitric oxide and cyclooxygenases in endothelium‐dependent relaxation of human internal mammary artery and saphenous vein as bypass grafts

Protecting the Crossover Right Internal Thoracic Artery Bypass Graft With a Pedicled Thymus Flap

The right internal thoracic artery graft is placed in jeopardy during repeat sternotomy as it crosses the aorta anteriorly to reach its left-sided coronary targets. We have devised a way of protecting it by means of a pedicled flap taken from the thymic remnants. The flap is easily developed without unduly increasing operative time and morbidity, and it is expected to prevent inadvertent injuries to the graft in the case of mediastinal reentry. Starting in 1999, suitable flaps were obtained in 955 of 1,034 patients (92.4%) receiving an anteaortic crossover right internal thoracic artery-to-coronary graft in our division.

3D multidetector CT angiographic evaluation of extralobar pulmonary sequestration with anomalous venous drainage into the left internal mammary vein in a paediatric patient

Pulmonary sequestration is a congenital lung malformation, defined by dysplastic and non-functioning lung tissue lacking normal tracheobronchial connections and accompanied by an anomalous systemic blood supply. Recognition of anomalous arteries and veins in pulmonary sequestration is paramount to making the correct diagnosis. In contrast to intralobar pulmonary sequestration, where anomalous venous drainage is usually into the pulmonary venous system, the pattern of anomalous venous drainage is more varied in extralobar pulmonary sequestration. To the best of our knowledge, anomalous venous drainage to the internal mammary vein in extralobar sequestrations has not been reported. We report an anomalous venous drainage into the internal mammary vein in an extralobar sequestration which was evaluated with 3D multidetector CT angiography.

Internal mammary artery and vein: Recipient vessels for free tissue transfer to the head and neck in the vessel‐depleted neck

Microvascular free tissue transfer is a standard reconstructive option for postablative defects of the head and neck. However, the success of this surgery requires suitable recipient vessels in the cervical region. This form of reconstruction can be particularly challenging in the vessel-depleted neck. While the internal mammary artery and vein (IMA/V) have been used extensively in breast reconstruction, there are few reports describing their use in head and neck reconstruction. We report the first case series of the use of the internal mammary vessels for head and neck microvascular reconstruction. We reviewed 5 cases of free tissue transfers to the head and neck in which extensive prior treatment precluded the use of more traditional recipient vessels in the neck or upper chest. A variety of free flaps were transferred for different reconstructive problems which included: chin/lower lip (n = 2), closure of widely patent tracheoesophageal puncture sites (n = 2), and pharyngoesophageal reconstruction following staged repair of a severe stenosis (n = 1). The radial forearm free flap was transferred in 4 patients and the rectus abdominus free flap in 1 patient. The IMA/V on the right side was prepared in all cases. All free flaps were successfully revascularized without the need for vein grafts and without the need for any microvascular revision procedures. The internal mammary artery and vein provide reliable, easily accessible recipient vessels for microvascular reconstruction in the vessel-depleted neck. The selection of free flap donor sites with long donor vessels facilitates the microvascular repair.

Robot Assisted Left Internal Thoracic Artery Harvesting in Minimally Invasive Direct Coronary Artery Bypass: Report of a Case

Coronary artery bypass grafting (CABG) is usually performed through a sternotomy. Minimally invasive direct coronary artery bypass grafting (MIDCABG) has been used recently in a select group of patients with severe lesions of the left anterior descending (LAD) coronary artery. CABG has been proven difficult to adapt to a totally endoscopic approach because of the inability to perform a precision microvascular-sutured coronary anastomosis with conventional endoscopic instrumentation. The Da Vinci telemanipulation system has six degrees of freedom and allows free orientation in space and a remote, tremor-free, three-dimensional visual image. We report hereby a 76-year-old male who suffered from substernal chest pain that radiated to the left shoulder for one day. Coronary angiography confirmed coronary artery disease with 90% occlusion of the LAD coronary artery. The patient volunteered to receive the operation. Robotically assisted left internal thoracic artery (LITA) harvesting and direct off-pump anastomosis to the LAD through small thoracotomy incisions were performed safely. The patient improved clinically and was free of angina at the six-month follow-up. We describe an alternative procedure for one-vessel disease using robotic takedown of the LITA and off-pump anastomosis to the LAD artery through small incisions. This procedure is associated with minimal blood loss and ventilatory requirements, and short stays in the intensive care unit and hospital.