A Technical Modification for Establishing Selective Antegrade Cerebral Perfusion during Pulmonary Endarterectomy.

Pulmonary endarterectomy (PEA) due to chronic thromboembolic pulmonary hypertension (CTEPH) is mainly performed in deep hypothermic circulatory arrest without additional cerebroprotective means. A 49-year-old man was treated by PEA for CTEPH by using selective antegrade cerebral perfusion by advancing the tip of the systemic perfusion cannula into the brachiocephalic trunk. The postoperative course was uneventful.

Surgical technique of lower lobe lung transplantation.

Among patients with end-stage lung disease awaiting lung transplantation, pediatric and small adult patients have a significantly lower chance of getting size-matched pulmonary grafts in time because of the severe scarcity of small donors. It is our strategy to perform lobar lung transplantations in small recipients with restrictive pulmonary disease once their clinical status demands urgent transplantation. Here we describe our surgical technique and discuss the benefits and risks of this procedure.

Percutaneous edge-to-edge repair of tricuspid regurgitation in congenitally corrected transposition of the great arteries.

A 62-year-old woman presented with shortness of breath and NYHA III. Severe heart failure was due to reduced systolic function. The woman reported of lung edema at two times. Computed tomography scan and magnetic resonance imaging showed a congenitally corrected transposition of the great arteries (CC-TGA). Echocardiographic findings revealed a high grade tricuspid regurgitation. For treatment of the tricuspid regurgitation, we used a percutaneous approach. The Evalve MitraClip(®) system has demonstrated feasibility and safety in the treatment of mitral regurgitation. Three months after successful tricuspid valve clipping, the patient is fine and NYHA score is reduced to grade I.

A novel innominate vein-to-common atrium fenestration at Fontan completion.

With the hypothesis of low thromboembolic risk and higher late postoperative spontaneous closure, a new fenestration technique during extracardiac total cavopulmonary connection was attempted. From 2008 to 2009, 14 consecutive patients received an innominate vein-common atrium 5-mm Gore-Tex (W.L. Gore and Associates, Flagstaff, AZ) graft fenestration. Monitoring was performed by contrast bubble echocardiography at hospital discharge and up to 6 months postoperatively. The technique proved safe and reproducible, did not add to surgical difficulty or time, and provided reliable fenestration of up to at least 3 weeks, with a high rate of spontaneous closure during intermediate follow-up.

Perioperative management to improve neurologic outcome in thoracic or thoracoabdominal aortic stent-grafting.

BACKGROUND: Thoracic or thoracoabdominal aortic stent-graft repair has shown a reduction in morbidity and mortality rates due to the procedure's advantages (no aortic cross-clamping, continuous distal aortic perfusion, no reperfusion injury). However, 3% to 12% of the patients are at risk of spinal cord ischemia. We investigated spinal cord protective measures with evoked potentials, cerebrospinal fluid drainage, and prevention of hypotension to minimize postoperative neurologic deficit. METHODS: Between November 2000 and July 2005, vital parameters and spinal cord function were monitored, including cerebrospinal fluid pressure and transcranial motor-evoked and somatosensory-evoked potentials in 36 stent-graft procedures (31 patients) on the thoracic or thoracoabdominal aorta. RESULTS: Stent-graft placement was technically successful in all patients. We achieved a survival rate of 100% without neurologic deficit after fast-track extubation. Eleven of 31 patients exhibited changes in evoked potentials during stent-graft deployment. In 12 of 31 patients (including the 11 with evoked potential alterations), cerebrospinal fluid pressure exceeded 15 mm Hg. Cerebrospinal fluid drainage and vital parameter adjustment were executed in those instances. We observed intraoperative evoked potential total recovery in 10 of 11 patients after these interventions. CONCLUSIONS: Interventions to improve spinal cord perfusion led to total recovery of spinal function in most patients (10/11). Therefore, spinal cord protective measures with motor- and somatosensory-evoked potential monitoring, cerebrospinal fluid drainage, and prevention of hypotension can reduce the incidence of spinal cord ischemia and improve the neurologic outcome of patients undergoing endovascular thoracic or thoracoabdominal aortic repair.

Neurophysiological monitoring during thoracoabdominal aortic endovascular stent graft implantation.

OBJECTIVE: The aim of this study was to evaluate the benefit of neurophysiological monitoring during thoracic and thoracoabdominal endovascular stent graft implantation. METHODS: The spinal cords of 21 patients undergoing endovascular stent graft implantation on the thoracic and thoracoabdominal aorta were monitored with transcranial motor-evoked potentials (tcMEP) and somatosensory-evoked potentials (SSEP). All patients underwent mild systemic hypothermia (34-35 degrees C), constant cerebrospinal fluid (CSF) pressure and vital parameter monitoring. If CSF pressure exceeded 15 mmHg, CSF-drainage was carried out. RESULTS: Three of the 21 patients (14%) exhibited short-term loss of tcMEP and SSEP after the deployment of the self-expanding endoprosthesis. We observed an intraoperative recovery of the evoked potentials in all cases. CSF-drainage was necessary in three of them. One patient, whose potentials were stable intraoperatively, developed paraparesis 3 weeks after the intervention. CONCLUSIONS: Neurophysiological monitoring has proved to be an ideal monitoring method to detect spinal cord ischemia during thoracic and thoracoabdominal endovascular stent graft implantation. Due to the advantages of endovascular therapy (no aortic cross-clamping, continuous distal perfusion, and no reperfusion injury), changes in potentials were seldom observed.

Sonic hedgehog myocardial gene therapy: tissue repair through transient reconstitution of embryonic signaling.

Sonic hedgehog (Shh) is a crucial regulator of organ development during embryogenesis. We investigated whether intramyocardial gene transfer of naked DNA encoding human Shh (phShh) could promote a favorable effect on recovery from acute and chronic myocardial ischemia in adult animals, not only by promoting neovascularization, but by broader effects, consistent with the role of this morphogen in embryogenesis. After Shh gene transfer, the hedgehog pathway was upregulated in mammalian fibroblasts and cardiomyocytes. This resulted in preservation of left ventricular function in both acute and chronic myocardial ischemia by enhanced neovascularization, and reduced fibrosis and cardiac apoptosis. Shh gene transfer also enhanced the contribution of bone marrow-derived endothelial progenitor cells to myocardial neovascularization. These data suggest that Shh gene therapy may have considerable therapeutic potential in individuals with acute and chronic myocardial ischemia by triggering expression of multiple trophic factors and engendering tissue repair in the adult heart.

Stem cell research and cell transplantation for myocardial regeneration.

Several human organs are not capable of functional regeneration following a tissue defect and react with scar formation. In stem cell transplantation, undifferentiated or partly differentiated precursor cells are applied to defective tissue for therapeutic regeneration. After promising preclinical investigations, the transplantation of autologous stem cells for myocardial infarction treatment is being transferred to clinical use. Mesenchymal stem cells and endothelial precursor cells derived from the bone marrow or circulating blood as well as skeletal myoblasts are employed in clinical trials. Furthermore, indications for cell transplantation and delivery routes vary considerably throughout current investigations. Initial results suggest a potential for restoration of cardiac function in stem cell-treated patients; however, the mechanisms are not fully understood. This overview will focus on objectives, recent achievements, and future perspectives of diverse stem cell transplantation approaches.

Synergistic effect of bone marrow mobilization and vascular endothelial growth factor-2 gene therapy in myocardial ischemia.

BACKGROUND: We performed a series of investigations to test the hypothesis that combining angiogenic gene therapy and cytokine (CK)-induced endothelial progenitor cell mobilization would be superior to either strategy alone for treatment of chronic myocardial ischemia. METHODS AND RESULTS: A swine model of chronic myocardial ischemia and a murine model of acute myocardial infarction were used in this study. In both models, animals were randomly assigned to 1 of 4 treatment groups: Combo group, intramyocardial vascular endothelial growth factor (VEGF)-2 gene transfer plus subcutaneous injection of CKs; VEGF-2, VEGF-2 gene transfer plus saline subcutaneously injected; CK, empty vector transfer plus CKs; and control, empty vector plus subcutaneous saline. Acute myocardial infarction was also induced in wild-type mice 4 weeks after bone marrow transplantation from enhanced green fluorescent protein transgenic mice to permit observation of bone marrow-derived cells in the myocardium after acute myocardial infarction. In chronic myocardial ischemia, combination therapy resulted in superior improvement in all indexes of perfusion and function compared with all other treatment groups. In the bone marrow transplant mice, double immunofluorescent staining revealed that the combination of CK-induced mobilization and local VEGF-2 gene transfer resulted in a significant increase in the number of bone marrow-derived cells incorporating into the neovasculature, indicating that recruitment and/or retention of bone marrow-derived progenitors was enhanced by mobilization and that local VEGF-2 gene transfer can provide signals for recruitment or incorporation of circulating progenitor cells. CONCLUSIONS: Mobilization of endothelial progenitor cells with cytokines potentiates VEGF-2 gene therapy for myocardial ischemia and enhances bone marrow cell incorporation into ischemic myocardium.

Transgenic and transmural revascularization: regional myocardial tissue pressure during chronic ischemia.

Channel patency and a cavito-myocardial pressure gradient are prerequisites for one potential mechanism of transmyocardial laser revascularization (TMLR), namely indirect (non-coronary) myocardial perfusion. We assessed the effect of TMLR combined with vascular endothelial growth factor (VEGF) on the myocardial tissue pressure (MTP) in chronic ischemia questioning firstly, whether transmural pressure allows perfusion of laser channels, and secondly, whether additional application of VEGF improves channel patency. One week after creation of an operative left anterior descending artery stenosis (2nd operation), pigs were designated to untreated ischemia (n=7), TMLR (n=8) or TMLR+VEGF-cDNA (2 mg intramyocardially, n=6). MTP and left ventricular pressure (LVP) were recorded simultaneously in the endo-, mid-, and epimyocardium before and after stenosis (1st operation), before and after therapy (2nd operation), and 12 weeks later (3rd operation). Myocardial samples were subjected to immunohistochemistry. Endo- and epimyocardial MTP exceeded LVP in all groups throughout the study, whereas midmyocardial MTP was constantly below LVP (P<0.05). Immediately after combined TMLR+VEGF, the endo-MTP decreased from 246.5+/-44.2 to 176.7+/-20.7 mmHg (P=0.043), remaining higher than LVP. After 12 weeks, it increased to 225.6+/-31.8 mmHg (P=0.04), but did not reach baseline values (P=0.04). Histological examination revealed occluded channels with surrounding vascular proliferation in both treatment groups. Additional VEGF-cDNA application in the vicinity of TMLR channels does not improve long-term patency. Direct blood flow from the cavity into the myocardium is impossible due to the high endomyocardial pressure. This limitation might be overcome by implantation of endomyocardial stents.

Transmyocardial laser revascularization combined with vascular endothelial growth factor 121 (VEGF121) gene therapy for chronic myocardial ischemia--do the effects really add up?

OBJECTIVE: Different therapy strategies for coronary disease in conventionally untreatable patients have been developed, among them transmyocardial laser revascularization (TMLR) and the application of growth factors. The objective of our study was to determine whether a combined therapy of TMLR with a vascular endothelial growth factor(121) (VEGF(121)) plasmid is able to stimulate the development of sufficient collateral circulation and hereby to preserve cardiac function. MATERIALS AND METHODS: A severe stenosis of the left anterior descending artery was created in healthy pigs. After 1 week, perfusion and regional contractility were assessed at baseline. Afterwards, the ischemic area was treated with TMLR (n=8), intramyocardial injection of naked plasmid DNA encoding VEGF(121) (n=7), or both (n=7). Control animals were left untreated (n=8). After 3 months, the animals were re-examined and underwent immunohistological analysis. RESULTS: The number of capillaries increased only after injection of VEGF(121) plasmid alone compared to untreated ischemia and to the other therapy groups, whereas the number of arterioles was higher following TMLR treatment alone or in combination with VEGF(121) than it was in the case in untreated ischemic animals. However, only combined VEGF(121)+TLMR therapy resulted in an improvement in regional myocardial blood flow in comparison with 1 week ischemia, indicating the efficient development of collateral circulation. In contrast, better regional contractility compared to the 1-week baseline, as well as restoration of the pre-ischemic values, were achieved by both VEGF(121) and combined VEGF(121)+TLMR therapies. CONCLUSIONS: This study of chronic myocardial ischemia with a porcine model indicates a synergistic action of TMLR and VEGF(121) gene therapy. Combined treatment alone achieved an increase of regional myocardial perfusion, which accompanied arteriogenesis and corresponded with the restoration of regional function.

Comparison of protein with DNA therapy for chronic myocardial ischemia using fibroblast growth factor-2.

OBJECTIVE: Treatment of coronary disease by growth factors has become an increasingly used strategy for otherwise untreatable patients and is subject to a number of clinical studies. The aim is to stimulate the development of a sufficient collateral circulation and hereby to rescue cardiac function. The objective of our study was to compare the effectiveness of fibroblast growth factor-2 (FGF-2) as protein and as naked plasmid DNA in a porcine model of chronic myocardial ischemia. MATERIALS AND METHODS: A severe stenosis of the left anterior descending artery (LAD) artery was created in healthy pigs. After 1 week, perfusion and regional and global contractility was assessed at baseline at rest and under stress. Afterwards, recombinant FGF-2 (n=6) or naked plasmid DNA encoding FGF-2 (n=7) was intramyocardially injected into the LAD territory. Control animals were left untreated (n=5). After 3 months, the animals were re-examined and underwent immunohistologic analysis. One animal received an Enhanced Green Fluorescent Protein plasmid. RESULTS: Plasmid-dependent protein synthesis was present in cardiomyocytes. FGF-2 protein as well as plasmid injections resulted in an increased number of capillaries and of arterioles compared with untreated ischemia. The improvement of the regional myocardial blood flow by FGF-2 plasmid therapy at rest might however indicate the effectiveness of the DNA application for the induction of a collateral circulation. A benefit from FGF-2 plasmid therapy was revealed with regard to regional contractility. Systemic hemodynamics were partially improved following plasFGF-2 treatment. CONCLUSIONS: In this porcine model of chronic myocardial ischemia, intramyocardial injection of FGF-2 plasmid was more effective than of FGF-2 protein in improving regional perfusion and contractility compared to untreated ischemia.

The combined use of transmyocardial laser revascularization (TMLR) and fibroblastic growth factor (FGF-2) enhances perfusion and regional contractility in chronically ischemic porcine hearts.

OBJECTIVE: The purpose of this study was to determine the combined effect of transmyocardial laser revascularization (TMLR) and recombinant human basic fibroblastic growth factor (rhFGF-2) treatment in chronically ischemic hearts. METHODS: To employ this porcine ischemic model, an operative severe stenosis of the left anterior descending artery (LAD) was created (first operation). One week later, the animals were studied at baseline (second operation) by analyzing perfusion (microsphere technique) and regional contractility (ultrasonic crystals). Afterwards, pigs were randomized into one of the four groups: ischemic control group (n = 7), TMLR-group (n = 7), FGF-2-group receiving 500 microg rhFGF-2 (n = 6), and FGF-2 + TMLR-group receiving TMLR with 500 microg rhFGF-2 (n = 6). Twelve weeks later, the animals were re-examined (third operation) and the hearts underwent additionally histochemical and immunohistologic analysis. RESULTS: Three months after therapy, regional myocardial blood flow (RMBF) in the LAD territory was significantly higher at rest in the FGF-2 group and FGF-2 + TMLR group compared to baseline, control and TMLR group (FGF-2 group: 1.17 +/- 0.10 versus baseline 0.28 +/- 0.10, P = 0.028; versus control 0.49 +/- 0.12, P = 0.01; and versus TMLR 0.34 +/- 0.20, P = 0.0081; FGF-2 + TMLR group: 0.88 +/- 0.29 versus baseline 0.41 +/- 0.14, P = 0.028; versus control 0.49 +/- 0.12, P = 0.019 and versus TMLR group 0.34 +/- 0.20 ml/g per min, P = 0.0032). Furthermore, the FGF-2 + TMLR-group demonstrated higher RMBF values in the LAD territory under stress conditions compared to baseline (1.79 +/- 0.69 versus 0.41 +/- 0.14; P = 0.028) and control (1.79 +/- 0.69 versus 0.78 +/- 0.55 ml/g per min; P = 0.038) at the end of the study. In contrast to these groups, RMBF in the control and TMLR group was unchanged. After 3 months, the FGF-2- and FGF-2 + TMLR-groups' regional contractility in the LAD territory revealed an improvement at rest (FGF-2: 84.00 +/- 26.22 versus baseline: 53.76 +/- 13.49, P = 0.003; FGF-2 + TMLR: 104.46 +/- 28.62 versus control: 61.27 +/- 5.13; P = 0.005 and versus TMLR: 59.74 +/- 41.23%; P = 0.041), whereas control and TMLR animals did not show any difference. TMLR as well as FGF-2 + TMLR treatment resulted in an increased number of capillaries and of arterioles in the channel area compared to untreated ischemia (P < 0.005). CONCLUSIONS: In contrast to the TMLR- and control group, CO(2)-laser revascularization combined with the application of intramyocardial growth factor, FGF-2, significantly ameliorates perfusion at rest and stress in this model of chronic regional ischemia, whereas sole FGF-2 application showed an improvement at rest only. This was mirrored by an enhancement of regional contractility in the FGF-2 + TMLR- and FGF-2-group at rest.

Percutaneous aortic valve replacement: an experimental study. I. Studies on implantation.

OBJECTIVE: The purpose of this preliminary study was to devise a new surgical procedure for minimally invasive aortic valve implantation with a transluminal technique. METHODS: The new collapsible heart valve was prepared by mounting a porcine aortic valve, taken from a freshly slaughtered pig, into a self-expandable nitinol stent by means of a suture technique. The outer diameter of the valved stent ranged from 15 to 23 mm, and the length ranged from 21 to 28 mm. Before implantation in vivo, these valved stents were tested in an in vitro circulatory system. Only in vitro-tested valved stents with a pressure gradient of less than 7 mm Hg and regurgitation of I degrees or less were used for transluminal aortic valve implantation in vivo. Six of these valved stents were implanted in the descending aorta and 8 in the ascending aorta of anesthetized pigs. The catheter delivery system (22F) was extraperitoneally inserted through the left iliac artery or the infrarenal aorta. Measurements for transvalvular gradient, valvular opening and closure, blood-flow characteristics, regurgitation, and macroscopic analysis were performed at baseline and after the observation period (164 +/- 48 minutes). RESULTS: This preliminary study contained 14 animals. One animal died of ventricular fibrillation. Technical failure occurred in 2 pigs as a result of stent twisting. At the end of the observation period, the 11 successfully implanted valved stents demonstrated low transvalvular gradients (mean end-systolic Deltarho(max) of 5.4 +/- 3.3 mm Hg for the descending aorta group, 5.4 +/- 1.2 mm Hg for the supracoronary group, and 5.4 +/- 1.1 mm Hg for the subcoronary group), which did not differ from their in vitro gradients. Two-dimensional echocardiography demonstrated complete valvular closure and opening in 5 of 5 cases. Angiography indicated only a physiologic jet of regurgitation (0 degrees ) in 8 animals and mild (I degrees ) regurgitation in 3 animals. Color Doppler ultrasonography indicated no regurgitation in 5 of 5 cases and minor paravalvular leakage in 1 case. CONCLUSION: Aortic valved stents can be successfully implanted without thoracotomy by using a transluminal catheter technique. Long-term function of the valves remains to be established.