Noninvasive Neuromonitoring of Hypothermic Circulatory Arrest in Aortic Surgery.

BACKGROUND AND AIMS: Circulatory arrest carries a high risk of neurological damage, but modern monitoring methods lack reliability, and is susceptible to the generalized effects of both anesthesia and hypothermia. The objective of this prospective, explorative study was to research promising, reliable, and noninvasive methods of neuromonitoring, capable of predicting neurological outcome after hypothermic circulatory arrest. MATERIALS AND METHODS: Thirty patients undergoing hypothermic circulatory arrest during surgery of the thoracic aorta were recruited in a single center and over the course of 4 years. Neuromonitoring was performed with a four-channel electroencephalogram montage and a near-infrared spectroscopy monitor. All data were tested off-line against primary neurological outcome, which was poor if the patient suffered a significant neurological complication (stroke, operative death). RESULTS: A poor primary neurological outcome seen in 10 (33%) patients. A majority (63%) of the cases were emergency surgery, and thus, no neurological baseline evaluation was possible. The frontal hemispheric asymmetry of electroencephalogram, as measured by the brain symmetry index, predicted primary neurological outcome with a sensitivity of 79 (interquartile range; 62%-88%) and specificity of 71 (interquartile range; 61%-84%) during the first 6 h after end of circulatory arrest. CONCLUSION: The hemispheric asymmetry of frontal electroencephalogram is inherently resistant to generalized dampening effects and is predictive of primary neurological outcome. The brain symmetry index provides an easy-to-use, noninvasive neuromonitoring method for surgery of the thoracic aorta and postoperative intensive care.

Transaortic Transcatheter Aortic Valve Implantation as a Second Choice over the Transapical Access.

BACKGROUND AND AIMS: In this report, we present our experience with the transaortic transcatheter aortic valve implantation using the SAPIEN valve. The procedural success, 30-day outcome, and survival up to 2 years are compared with the transapical access performed in patients in our institution. MATERIAL AND METHODS: Of a total of 282 transcatheter aortic valve implantation patients, 100 consecutive patients had a non-transfemoral approach. The transaortic and transapical access routes were used in 36 and 64 patients, respectively. The transaortic group had a higher mean logistic EuroSCORE (32.6 vs 25.2, p = 0.021) and more patients with left ventricular ejection fraction less than 40% (33.3% vs 14.1%, p = 0.023). RESULTS: The respective technical success rates for the transaortic and transapical groups were 100% and 95.2% (p = NS). There were significantly more perioperative hemodynamic problems necessitating cardiopulmonary resuscitation or mechanical circulatory support in the transapical group (18.8% vs 2.8%, p = 0.023). The transaortic group had a slightly shorter hospital stay (7 vs 8 days, p = 0.018). The 30-day mortality was 8.6% and 10.9% in the transaortic and transapical group, respectively (p = NS). Combined safety outcome was similar in both groups at 30 days. The respective 1-year survival rates for the transaortic and transapical groups were 71.5% and 68.3%, respectively (p = NS). CONCLUSION: The trans transcatheter aortic valve implantation is a considerable choice to transapical approach. Despite a higher risk patient cohort, the clinical outcome is at least comparable to the transapical transcatheter aortic valve implantation, and it can be utilized as a second choice for patients with prohibitive iliac-femoral anatomy for transfemoral access.

Tenascin is expressed in post-transplant obliterative bronchiolitis.

Tenascin is expressed in inflammatory and fibroproliferative processes, both contributing to posttransplant obliterative bronchiolitis (OB) in association with epithelial cell injury and airway obliteration. We studied bronchial allografts to elucidate the role of tenascin during this alloimmune response. Bronchial segments were subcutaneously implanted into eight pigs. Allografts and autograft controls were serially obtained until total obliteration in allografts and processed for histology and immunocytochemistry for CD4, CD8, and tenascin. Findings were graded on a scale from 0 to 3. In autografts the operative epithelial damage recovered and bronchi stayed patent with mild-graded fibrosis and inflammation. Partial recovery was observed in allografts on day 4, thereafter the epithelial loss gradually increased. Total recovery was achieved on day 11 (P < .001). Fibroblast proliferation resulted in total luminal obliteration on day 21 (P < .001). The number of inflammatory cells increased rapidly (P < .05) with numerous CD4+ and CD8+ cells on day 14 (P < .0001). Prior to total epithelial loss in allografts, tenascin expression was observed on day 7 in 69% of epithelial cells, whereas in only 5% of epithelial cells in recovered autografts. Paralleling the most intense fibroproliferation, tenascin-positive cells were observed in the bronchial wall on day 7 and day 11 (P < .001). Tenascin expression was demonstrated during the inflammatory response and fibroblast proliferation during the early stage of obliterative bronchiolitis showing that tenascin contributes to posttransplant obliterative bronchiolitis development.

L-Arginine in lung graft preservation and reperfusion.

BACKGROUND: Inhaled nitric oxide has been shown to ameliorate early lung graft dysfunction. It improves oxygenation by inducing pulmonary vasodilatation in well-ventilated lung areas, and it also modulates leukocyte-endothelium interactions. We used a porcine, single lung transplantation model to evaluate whether the benefits of exogenously administered gas could be achieved easier by adding L-arginine, the substrate of endogenous nitric oxide synthesis, as an additive to the flush solution and intravenously during reperfusion. METHODS: Six pig lungs were flushed with modified Euro-Collins solutions containing L-arginine (2 g/liter). After cold (4 degrees C) storage, the left lung was transplanted. Ischemic time was 260 minutes. The recipients received intravenous boluses of L-arginine (30 mg/kg), followed by infusion (20 mg/kg/min) during the first 30 minutes of reperfusion. Six control animals received saline as placebo. We measured the blood flow and pulmonary vascular resistance (PVR) in the transplanted and in the native lung using a right heart bypass model. We measured blood gases, leukocyte counts, plasma free-radical trapping capacity, and diene conjugates in pulmonary venous blood and myeloperoxidase activity of the lung tissue. RESULTS: Pulmonary vascular resistance was 4 to 5-fold higher in the transplanted lung than in the native lung, which received 80% of the total blood flow. L-arginine reduced PVR by 30% in the native lung (p < 0.001), but not in the transplanted lung. L-arginine had no effect on oxygenation or carbon dioxide exchange of the transplanted lung. Nor did L-arginine treatment have any effect on leukocyte sequestration or myeloperoxidase activity in the transplanted lung. The plasma antioxidant capacity in venous blood of the transplanted lung almost doubled shortly during early reperfusion without influence of L-arginine. CONCLUSIONS: L-arginine reduced PVR in the native lung but did not improve pulmonary hemodynamics, gas exchange, or reduce leukocyte sequestration of the transplanted lung.

Inhaled NO and prostacyclin during porcine single lung transplantation.

BACKGROUND: Increased pulmonary vascular resistance (PVR) and decreased arterial oxygenation frequently complicate lung transplantation. Inhaled nitric oxide (NO) and aerosolized prostacyclin (PGI2) both dilate the pulmonary vasculature and improve oxygenation in adult respiratory distress syndrome. We investigated whether similar effects would occur during early reperfusion of a lung graft. METHODS: Eighteen pigs underwent left lung transplantation. We measured blood flow distribution, mean pulmonary artery pressure, PVR, and gas exchange in each lung separately. Animals were randomized into three groups to receive NO (10 ppm/30 minutes, 40 ppm/30 minutes), nebulized PGI2 (25 microg/mL/30 minutes, 50 microg/mL/30 minutes), or no drugs (control). RESULTS: In the transplanted lung, PVR was significantly higher than in the native lung. Pulmonary vascular resistance of the transplanted lung was lower in the NO and PGI2 groups in comparison with the control group. During the first hour of inhalation, NO decreased PVR more than PGI2. Neither drug improved oxygenation in the graft. CONCLUSIONS: Nitric oxide and PGI2 decreased PVR of the transplanted lung slightly, but the effect did not produce a normal pressure in pulmonary vasculature.

The effect of nitecapone on early graft function in experimental single lung transplantation.

Nitecapone is an antioxidant molecule which has been shown to protect the heart against ischemia-reperfusion injury. We investigated whether a similar effect could be detected on lung graft preservation in a porcine model of single lung transplantation. Donors received either nitecapone or placebo in a modified Euro-Collins pulmonary flush solution. After cold storage for 19 h the left lung was transplanted. Patients in the nitecapone group received a nitecapone infusion during the graft reperfusion. A right-side heart bypass was used to measure flow distribution and pulmonary vascular resistance (PVR) in the recipient's transplanted and native lungs, respectively. Pulmonary vein blood samples were analyzed for blood gases, free radical trapping capacity and diene conjugates. PVR was high in the transplanted lung, which received only 20% of the blood flow. Oxygen tension in the transplanted lung was low (2.3-26.7 kPa). Nitecapone treatment increased the plasma free radical trapping capacity threefold. In spite of this increase in antioxidative capacity nitecapone could not protect the lung against ischemia-reperfusion injury when pulmonary hemodynamics, gas exchange or plasma diene conjugates were used as measures of lung graft function.

Bronchial artery revascularization improves tracheal anastomotic healing after lung transplantation.

The study aimed to clarify the role of direct bronchial artery revascularization (BAR) after en bloc double-lung (DLT) and heart-lung transplantation (HLT). Group I comprised eight patients with en bloc DLT or HLT and successful BAR, while group II included 14 DLT or HLT cases without BAR or with failed BAR. From these groups, 2 subgroups were extracted: group III, including 6 cases of en bloc DLT with successful BAR and group IV 10 HLT cases without or with failed BAR. Airway healing was evaluated at bronchoscopy and patency of BAR with angiography. Pulmonary viral, bacterial and fungal infections, rejections and bronchiolitis obliterans syndrome (BOS) were registered. Tracheal healing at 2 weeks and 3 months was better in group I than in group 1 (p = 0.003 and p = 0.05, respectively). Compared with group IV, tracheal anastomotic healing at 2 weeks was better in group III (p = 0.007) and tended to be better also after 3 months (p = 0.07). The incidence of infections, rejection or BOS did not differ between groups I and II. BAR thus improved healing of tracheal anastomosis.

Donor lung pretreatment with prostaglandin E(1) does not improve lung graft preservation.

Prostaglandin E(1) (PGE(1)) is widely used to improve early graft function after lung transplantation, but some studies have questioned its benefits. Therefore we evaluated the effect of donor pretreatment with PGE(1) in our porcine model of single lung transplantation. Donors received PGE(1) or placebo intravenously before flushing the pulmonary artery with modified Euro-Collins solution. After cold storage, the excised left lung was transplanted. Ischemic time was 4 h. We used our right side heart bypass model to measure standardized pulmonary vascular resistance and to study blood flow distribution between recipient's native and transplanted lung. Systemic and pulmonary hemodynamics and gas exchange were also measured. After transplantation, pulmonary vascular resistance was significantly higher in the transplanted lung, which received only one fourth of the total pulmonary blood flow. PGE(1) pretreatment did not improve pulmonary hemodynamic parameters, or gas exchange.