No abstract available.
Heart ; Korea ; Thoracic Surgery

In Japan, doctors inexperienced stent-graft new devices are required to secure agreement on criteria and choice of the device size in endovascular aneurysm repair (EVAR) from experienced doctors. It was hoped that strict patient selection might reduce the learning curve for initial successes in given procedures. In a leading center in Japan, a number of cases which were scheduled for operation at other institutes were evaluated anatomically. We surveyed the initial success of Zenith AAA system implantation in the remaining cases by inexperienced doctors and evaluated the results. This study aimed to verify the validity of strict patient selection in improving the success rate of inexperienced doctors. We enrolled 112 consecutive patients from 19 institutes, who were scheduled for repair between January and October in 2007. All patients were evaluated on the basis of a less-than-3mm reconstructed CT image. Mean patient age was 76±5.7 years. All cases satisfied the Zenith's anatomic prerequisites. Fifteen cases were excluded for various reasons, the major reason being insufficiency of the proximal landing zone (LZ) length, angle and contour. The second reason was difficulty to approach via the iliac artery. Ninety seven cases were included, of which 17 cases were low-risk candidates for EVAR. Medium-risk seventy two cases requiring some advice to avoid problems with device size, technique of implantation and choice of main-body side. Eight cases were high-risk, requiring the presence of an experienced surgeon. Excluded cases had significantly shorter proximal LZ, larger aortic diameters 15mm below the renal artery and tortuous access routes on preliminary measurement by inexperienced doctor. Perioperative mortality was 0%, while the major complications were injury to the iliac artery in one high-risk case and thromboembolism of the superficial femoral artery in another. Perioperative proximal type I endoleak occurred in 5 cases. In 3 of these cases, the endoleak was eliminated by implantation of a Palmatz stent. In the other 2 cases, it disappeared within a month without additional procedures. These cases had a significantly greater angle between the proximal LZ and the suprarenal aorta and significant amount of mural thromboses in the proximal LZ. Perioperative type III endoleak occurred in 3 cases. In all cases the endoleak was eliminated by additional procedure. Perioperative type II endoleak occurred 8 cases. In 3 of these cases, the endoleak disappeared within a month. In the 5 other cases, the endoleak did not disappear. Mid-term results showed iliac leg thromboembolism in one case and new type II endoleaks in 3 cases. Type II endoleak occurred in cases which had significantly greater angles between the proximal LZ and the aneurysm. The results which were evaluated in our center had excellent perioperative and mid-term outcomes. We think this evaluation system is effective for risk assessment and reduces the learning curve in EVAR. In anatomically marginal cases, it is possible for proximal type I endoleak and injury of the iliac artery to occur. It is impossible to exclude these marginal cases if treatment need for EVAR is a priority. In these cases, lessexperienced operators should be trained in troubleshooting techniques in advance.

The use of the internal mammary artery (IMA) is now routine in most coronary artery bypass grafting (CABG) because of its improved long-term patency and survival. A small but important percentage of these patients will require valve surgery and thoracic aortic aneurysm repair following CABG. These operations present a challenging problem for the cardiac surgeon because of difficulties regarding approach, dissection around the IMA and optimal myocardial protection. We investigated surgical results and the effectiveness of various methods of myocardial protection in 8 patients who underwent reoperations between December 1983 and June 2005. The mortality was 13%. There were 2 perioperative myocardial infarctions (25%), 6 cases of prolonged ventilation (75%), 3 cases of low output syndrome (38%), 1 case of acute renal failure (13%) and 1 case of sepsis (13%). We carried out resternotomy for 6 patients without any hospital death or perioperative myocardial infarction. Our reoperation approach had acceptable risk control with resternotomy, avoidance of dissecting the IMA and hypothermic perfusion.

We describe a case of postoperative aortic valve regurgitation (AR) after arterial awitch operation (ASO) successfully managed by the modified Konno procedure. A 4-year-old girl with complete transposition of the great arteries (TGA, Type II) had undergone the ASO (LeCompte maneuver) at 10 days of age. Because of progression of moderate AR 4 years after ASO, the modified Konno procedure with aortic valve replacement (SJM 21mm) was successfully performed. She remains in good clinical condition at the last follow-up at 5 years.

Prosthetic and bioprosthetic materials currently in use lack growth potential and therefore must be repeatedly replaced in pediatric patients as they grow. Tissue engineering is a new discipline that offers the potential for creating replacement structures from autologous cells and biodegradable polymer scaffolds. In May 2000, we initiated clinical application of tissue-engineered vascular grafts seeded with cultured cells. However, cell culturing is time-consuming, and xenoserum must be used. To overcome these disadvantages, we began to use bone marrow cells, readily available on the day of surgery, as a cell source. Since September 2001, tissue-engineered grafts seeded with autologous bone marrow cells have been implanted in 44 patients. The patients or their parents were fully informed and had given consent to the procedure. A 3 to 10ml/kg specimen of bone marrow was aspirated with the patient under general anesthesia before the skin incision. The polymer tube serving as a scaffold for the cells was composed of a copolymer of lactide and ε-caprolactone (50: 50) which degrades by hydrolysis. Polyglycolic or poly-l-lactic acid woven fabric was used for reinforcement. Twenty-six tissue-engineered conduits and 19 tissue-engineered patches were used for the repair of congenital heart defects. The patients' ages ranged from 1 to 24 years (median 7.4 years). All patients underwent a catheterization study, CT scan, or both, for evaluation after the operation. There were 4 late deaths due to heart failure with or without multiple organ failure or brain bleeding in this series; these were unrelated to the tissue-engineered graft function. One patient required percutaneous balloon angioplasty for tubular graft-stenosis and 4 patients for the stenosis of the patch-shaped tissue engineered material. Two patients required re-do operation; one for recurrent pulmonary stenosis and another for a resulting R-L shunt after the lateral tunnel method. Kaplan-Meier analysis in relation to patients' survival was 95% within 3 years. There was only 1 patient (who underwent a total cavo-pulmonary connection procedure) requiring re-intervention in the tubular graft group and the material-related event-free rate was 96% within 3 years. This tissueengineering approach may provide an important alternative to the use of prosthetic materials in the field of pediatric cardiovascular surgery. As it is living tissue, these vascular structures may have the potential for growth, repair, and remodeling. However, this approach is still in its infancy, further studies to resolve the problems presented, and longer follow-up in patients are necessary to confirm the durability of this approach.

When homo- or isograft was used as a right ventricle-pulmonary artery bypass in the Rastellitype procedure for congenital heart disease, reoperation was mandatory due to calcification and conduit stenosis after several years. However, the survival period of intimal cells or smooth muscle cells has not been clarified, nor has the question of whether the calcification is due to an immunoreaction or not. Thus, to observe the geometrical or pathological changes of the grafts, an experimental model of homograft transplantation was established using rats' aorta, where cyclosporine A (CsA) was given after the transplantation. The rats used were 8 or 9 weeks old. Male King rats were the donors, and female Lewis rats were the recipients. The descending thoracic aorta was transplanted to the infra-renal abdominal aorta. There were 2 experimental groups; one in which CsA was not given (n=35), and the other in which CsA was given (n=44). The animals were sacrificed at 1, 2, 4, 6, 8, and 12 weeks after the transplantation, and were examined by an optical microscope after slicing longitudinally. The area of the cross-section, intima and the media of the vessel were calculated by 2 ways; manually, and by computer. These data were used to calculate and analyze the percentage of intima-media area, the ratio of the intima/media area, and the percentage of intima area and media area. The effect of suppression of the percentage of intima-media area and the percentage of the intima area were revealed to be significant at an acute stage after brief high dose CsA administration. From this result, we suggest that there is a possibility of a rejective reaction participating in the intimal hyperplasia in the acute phase after homograft transplantation.

We performed the Senning operation and pulmonary valvotomy in an 11-month-old baby with transposition of the great arteries (TGA) with an intact ventricular septum (IVS), and bicuspid pulmonary valvular stenosis associated with pulmonary hypertension (PH). Preoperative catheterization showed a pressure gradient (PG) between the left ventricle (LV) and main pulmonary artery (MPA) of 35mmHg, mean pulmonary artery pressure (MPAP) of 56mmHg, and pulmonary vascular resistance (PVR) of 11.2unit·m². The pure oxygen inhalation test showed a decrease in MPAP from 56 to 38mmHg, and a decrease in PVR from 11.2 to 5.5 unit·m². We could not perform lung biopsy to determine the surgical indications in terms of PH due to preoperative progressive congestive heart failure in this patient. Postoperative catheterization (28 days after the Senning operation) showed a decrease in PG between the LV and MPA to 8mmHg, and MPAP also decreased to 17mmHg. Two radical operations were possible in this patient. One was the arterial switch operation (ASO), and the other was the atrial switch operation, i. e. the Senning or the Mustard operation. We selected the Senning operation because there was the possibility that the new aortic valve might develop persistent stenosis and regurgitation after ASO and pulmonary valvotomy. The Senning operation may be an alternative in selected patients with TGA with IVS and pulmonary valvular stenosis.

A 3-year-old girl was given a diagnosis of coronary arteriovenous fistula associated with a single right coronary artery on cardiac catheterization. The left coronary artery arose from the proximal part of the right coronary artery. The dilated left coronary artery ran in front of the right ventricular outflow tract and then divided into the left anterior descending branch and the left circumflex artery. A coronary arteriovenous fistula was in the left main coronary artery and opened into the right ventricular outflow tract. Under cardiopulmonary bypass and cardiac arrest, a transverse incision was made at the right ventricular outflow tract 1cm below the dilated vessel and the 5-mm oval-shaped orifice of the fistula was identified. This fistula was closed with a pledgetted mattress suture reinforced with over-and-over suture. Catheterization 8 months after surgery demonstrated no residual shunt and she has been doing well.

When local hemostatic agents are used in surgery, rapid dissolution followed by prompt absorption without adverse effect after successful hemostasis are essential qualities. Residual hemostatic materials greatly influence host cells during the wound healing process. Biocompatibility of material is also essential. Furthermore, hemostatic agents also should be free of cytotoxicity that may block mitosis and migration of host cells, so that wound healing can proceed smoothly. For the evaluation of biocompatibility and cytotoxicity, 4 commercially available hemostatic agents; oxidized regenerated cellulose (Surgicel^®), gelatin sponge (Spongel^®), microfibrillar collagen (Avitene^®) and cotton type collagen (Integran^®) were tested in vitro and in vivo. The hydrogen ion concentration (pH) of culture medium containing hemostatic agents was measured. Fibroblasts were cultured with the hemostatic agents in petri dishes for 5 days. A rabbit ear chamber (REC) model was used to evaluate tissue compatibility and the healing process. Each hemostatic agent was placed in the REC and evaluated macroscopically once a week up to 5 weeks. At 72h, the pH of the culture medium containing Surgicel was low at 7.2, while they stayed between 7.7-7.8 with the other agents. In the fibroblast culture containing Surgicel, cell detachment occurred and the cell numbers decreased, while no particular changes occurred with other hemostatic agents. In the REC model, after 5 weeks Surgicel was dissolved and remained in the effusion, and the healing process was disturbed by inflammation. Spongel was dissolved and absorbed, with normal vasculature. Avitene was dissolved and remained in the effusion, but did not induce strong inflammation. With Integran, the healing process was prompt but the material was still recognizable at 5 weeks. The 4 hemostatic materials tested showed differences in biocompatibility and cytotoxicity. The ability of hemostasis is important; however, after hemostasis is achieved, unused hemostatic material should be eliminated, leaving as little hemostatic agent as possible to avoid postoperative complications.