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Background The “frozen elephant trunk” procedure (FET) represents the therapy of choice for extended aortic diseases. The aim of our study was to analyze whether 90 minutes of selective cerebral perfusion (SCP) at 28°C followed by permanent occlusion of the thoracic segmental arteries (TSA) would cause spinal cord ischemia in a porcine model. Methods 14 pigs (41 ± 3 kg) were cooled on CPB to 28°C. After aortic clamping, SCP was established for 90 minutes. Randomly, in 7 animals the TSA were clipped (T4–T13); the TSA of 7 animals remained untouched. After the animals were weaned from CPB, hemodynamic data were registered for 120 minutes. Regional spinal cord blood flow (SCBF) was calculated, and motor-evoked potentials (MEP) were assessed at 6 time points. After sacrifice of the animals, the spinal cord was analyzed histologically by use of a schematic grading system (0 = normal; 8 = total necrosis). Results During SCP the SCBF was maintained at baseline (5.9 ± 2.4 mL/min/100 g) in the T4–T13 region but showed a decrease (from 8.4 ± 4.3 to 1.3 ± 1.5 mL/min/100 g) in the L1–L5 region. During reperfusion it increased, with two to three times higher values in the nonclipped animals. After 90 minutes of SCP, the MEP reached lower levels in the L1–L5 region of the TSA-clipped animals: 59% ± 7% vs 84 ± 15% (vastus medialis muscle) and 48% ± 6% vs 82% ± 26% (tibialis anterior muscle). The MEP recovered only in the nonclipped group. Higher ischemia rates were seen in the L1–L5 region of the TSA-clipped animals (score: 6.0 ± 0.6 vs 2.5 ± 2.3). Conclusions 90 minutes of SCP provided sufficient spinal cord protection during arch replacement at 28°C. In combination with permanent TSA occlusion, the lumbar spinal cord perfusion may be altered, which causes functional and structural damage. [ABSTRACT FROM AUTHOR]

Background: Although hypothermic selective cerebral perfusion (SCP) is widely used for cerebral protection during aortic surgery, little is known about the ideal pump-flow management during this procedure. This study explored cerebral hemodynamics and metabolism at two different flow rates. Methods: Fourteen pigs (33 to 38 kg) were cooled on cardiopulmonary bypass to 25°C. After 10 minutes of hypothermic circulatory arrest, the animals were randomly assigned to 60 minutes of SCP at two different pump flow rates: 8 mL·kg −1 ·min −1 (n = 7) and 18 mL·kg −1 ·min −1 (n = 7). Microspheres were injected at baseline, coolest temperature, and at 5, 15, 25, and 60 minutes of SCP to calculate cerebral blood flow, cerebral vascular resistance, metabolic rate, and intracranial pressure. Results: Cerebral blood flow decreased during cooling to 41% of the baseline value (from 57 ± 10 to 23 ± 4 mL·min −1 ·100 g −1 ). It recovered during the initial 15 minutes of SCP, showing a significantly higher increase (p = 0.017) at high-flow versus low-flow perfusion (139 ± 41 versus 75 ± 22 mL· min −1 ·100 g −1 ). After 60 minutes of SCP the cerebral blood flow almost returned to baseline values in the low-flow group (43 ± 25 mL·min −1 ·100 g −1 ), but showed an unexpected decrease (30 ± 7 mL·min −1 ·100 g −1 ) in the high-flow group. The highest regional cerebral blood flow was seen in the cortex (66 ± 12 mL·min −1 ·100 g −1 ), followed by the cerebellum (63 ± 12 mL·min −1 ·100 g −1 ), the pons (51 ± 17 mL·min −1 ·100 g −1 ), and the hippocampus (36 ± 9 mL·min −1 ·100 g −1 ). Intracranial pressure increased from 11 ± 3 to 13 ± 5 mm Hg during cooling on cardiopulmonary bypass. During low-flow SCP, it stayed stable at baseline values, whereas high-flow perfusion resulted in significantly higher intracranial pressures (17 ± 3 mm Hg; p = 0.001). Changes in cerebral vascular resistance and metabolic rate showed no significant differences between the groups. Conclusions: High-flow SCP provides no benefit during long-term SCP at 25°C. Higher cerebral blood flow during the initial SCP period leads to cerebral edema, with no profit in metabolic rate. [Copyright &y& Elsevier]

Objective: The effect of perfusion pressure on cerebral hemodynamics and metabolism during selective cerebral perfusion in patients undergoing aortic surgery is still unknown. This study explored cerebral blood flow, metabolic rate, and intracranial pressure at different pressure rates. Methods: Twenty-five pigs (32–38 kg) were cooled during cardiopulmonary bypass to 25°C. After 10 minutes of hypothermic circulatory arrest, the animals were randomized to 60 minutes of selective cerebral perfusion at 3 different perfusion pressures: group I (n = 8), 40 mm Hg; group II (n = 9), 60 mm Hg; and group III (n = 8), 80 mm Hg. Microspheres were injected at baseline, the coolest temperature, and 5, 15, 25, and 60 minutes of selective cerebral perfusion, respectively, to calculate cerebral hemodynamics. Results: Cerebral blood flow decreased during cooling to 54% of baseline value (50 mL/min per 100 g) and recovered in all groups during the first 15 minutes of selective cerebral perfusion. In groups I and II it reached 110% to 113% of baseline values, whereas group III animals showed significantly higher values (P 25min = .003) during the first 25 minutes of selective cerebral perfusion (360%; 153 mL/min per 100 g). Cerebral blood flow decreased in all groups over the following 35 minutes of selective cerebral perfusion to 57% of baseline value. Cooling to 25°C decreased the intracranial pressure to 10 mm Hg (93%). During selective cerebral perfusion, groups I and II showed a further intracranial pressure decrease to 45% and 82%, respectively, whereas group III, with 15 mm Hg (128%), had significantly higher intracranial pressure values at the end of selective cerebral perfusion (P 25min = .03 and P 60min = .02). The metabolic rate decreased to 30% of the baseline value during cooling, reaching 34% to 38% after 60 minutes of selective cerebral perfusion, with no significant differences between groups. Conclusion: High-pressure perfusion provides no benefit during long-term selective cerebral perfusion at 25°C. Higher cerebral blood flow during the initial 25 minutes of selective cerebral perfusion leads to cerebral edema, with no alteration in metabolic rate. [Copyright &y& Elsevier]

Background: The new technique of minimally invasive transapical aortic valve implantation (TAP-AVI) deals with high-risk patients and despite the absence of cardiopulmonary bypass it might lead to renal impairment. The aim of this study was to estimate the risk of the development of acute kidney injury (AKI) after TAP-AVI and to identify possible risk factors with regard to the morbidity and mortality of the patients. Methods: Data of 30 consecutive patients undergoing TAP-AVI were recorded and followed up for 8 weeks. Postoperative AKI has been defined according to RIFLE criteria. Two patients on chronic hemodialysis have been followed up. Results: Of 28 patients, AKI occurred in 16 patients (57%). Statistical analysis revealed no influence on the risk of developing AKI caused by the dose of applicated contrast medium (p = 0.09), the patient''s age (p = 0.5), or the existence of diabetes (p = 0. 16). Analysis concerning the relationship between a preexisting coronary heart disease and AKI showed a tendency to be associated with a higher risk of the development of AKI (70% preexisting congenital heart disease in the AKI group versus 50%; p = 0.28). Only a preoperative serum creatinine greater than 1.1 mg/dL was a strong predictor for developing AKI (p < 0.01). Length of stay in the intensive care unit and the complete length of hospital stay revealed no difference with regard to postoperative development of AKI though statistical analysis showed a trend to a higher mortality in the AKI group (27% vs 6%); univariate analysis did not reach statistical significance (p = 0.13). Conclusions: The TAP-AVI seems to be a feasible procedure for high-risk patients with a clear risk of developing AKI. Patients at risk should be identified and, if indicated, already preoperatively treated in collaboration with the attending nephrologists. [Copyright &y& Elsevier]

Background: Hypothermic circulatory arrest (HCA) and antegrade selective cerebral perfusion (ASCP) are utilized for cerebral protection during aortic surgery. However, no consensus exists regarding optimal ASCP-temperature showing a tendency toward higher values during the last years. This study investigates regional changes of cerebral blood flow (CBF) during ASCP at two temperatures. Methods: In this blinded study, 20 pigs (35 to 37 kg) were randomized to two groups. Animals were cooled to 10 minutes of HCA followed by 60 minutes of ASCP. Afterward the animals were perfused at 25°C and 30°C according to the study group. Fluorescent microspheres were injected at seven time points during the experiment to calculate total and regional CBF. Hemodynamics, cerebrovascular resistance (CVR) and cerebral metabolic rate of oxygen (CMRO2) were assessed. Tissue samples from the cortex, cerebellum, hippocampus, and pons were taken for microsphere count. Results: The CBF and CMRO2 decreased significantly (p < 0.002) during cooling in both groups; it was significantly higher throughout ASCP in the 30°C versus the 25°C group (p = 0.0001). These findings were similar among all brain regions, certainly at different levels. The CBF increased significantly (p = 0.002) during the early period of ASCP for analyzed regions and decreased significantly (p = 0.034) below baseline after 60 minutes of ASCP, reaching critical levels in the hippocampus and neocortex. The hippocampus turned out to have the lowest CBF, while the pons showed the highest CBF. Thirty minutes and more ASCP provides less CBF compared with baseline values at both temperatures. Conclusions: Antegrade selective cerebral perfusion improves CBF in all regions of the brain for a limited time. Our study characterizes the brain specific hierarchy of blood flow during ASCP. These dynamics are highly relevant for clinical strategies of perfusion. [Copyright &y& Elsevier]

: BackgroundThis study explored the impact of an interval of hypothermic circulatory arrest (HCA) preceding selective cerebral perfusion (SCP) on cerebral physiology and outcome. This protocol allows use of SCP during aortic surgery without the threat of embolization inherent in balloon catheterization of often severely atherosclerotic cerebral vessels.: MethodsIn this blinded study, 30 pigs (20 to 22 kg) were randomized after cooling to 20°C. Pigs in the HCA-CPB group (n = 10) underwent 30 minutes of HCA followed by 60 minutes of total body perfusion (CPB); HCA-SCP pigs (n = 10) underwent 30 minutes of HCA followed by 60 minutes of SCP, and SCP pigs (n = 10) had 90 minutes of SCP without prior HCA. Fluorescent microspheres enabled calculation of cerebral blood flow during perfusion and recovery. Hemodynamics, intracranial pressure, cerebrovascular resistance, and cerebral oxygen consumption were also monitored. Daily behavioral scores were obtained for 7 days postoperatively.: ResultsIn all groups, cerebral oxygen consumption fell significantly with cooling (p < 0.0001), remained low during perfusion, and rebounded promptly with rewarming; cerebral oxygen consumption was significantly (p = 0.027) greater during SCP than during HCA-CPB. Cerebral blood flow was significantly higher throughout SCP in the HCA-SCP group (p < 0.0001) than with CPB. Cerebrovascular resistance during SCP and HCA-SCP was significantly lower (p = 0.036) than during CPB. Behavioral scores were significantly better with SCP than with HCA-CPB throughout recovery, but did not differ between SCP and HCA-SCP.: ConclusionsThis study suggests that a short period of HCA preceding SCP provides global cerebral protection comparable to continuous SCP, implying that in clinical practice, a short period of HCA to reduce risk of embolization will not compromise the superior cerebral protection provided by SCP. [Copyright &y& Elsevier]

This case report illustrates our experience with transapical minimally invasive aortic valve implantation in a patient with an extended aneurysm of the thoracoabdominal aorta, who had previously undergone a replacement of the ascending aorta with concomitant aortic valve reconstruction (David procedure). Endovascular stent grafting of the descending aorta was also performed. The implantation of a 23-mm SAPIEN valve (Edwards Lifesciences, Irvine, CA) did not interfere with the existing 26-mm aortic Hemashield prosthesis (Boston Scientific, Natick, MA) or the previously implanted endograft in the descending aortic position. No paravalvular leakage with aortic valve regurgitation, prosthesis instability, or coronary malperfusion was seen after valve implementation. [ABSTRACT FROM AUTHOR]

In this case we illustrate our experience with transapical minimal invasive aortic valve replacement in a patient who previously underwent mitral valve replacement. The implantation did not interfere with the existing prosthesis and could even be used as a further landmark, helping height positioning of the aortic valve. [Copyright &y& Elsevier]

Temporary (TND) or permanent neurologic dysfunctions (PND) represent the main neurological complications following acute aortic dissection repair. The aim of our experimental and clinical research was the improvement and update of the most common neuroprotective strategies which are in present use., Hypothermic Circulatory Arrest (hca): Cerebral metabolic suppression at the clinically most used temperatures (18-22°C) is less complete than had been assumed previously. If used as a 'stand-alone' neuroprotective strategy, cooling to 15-20°C with a jugular SO(2) ≥ 95% is needed to provide sufficient metabolic suppression. Regardless of the depth of cooling, the HCA interval should not exceed 25 min. After 40 min of HCA, the incidence of TND and PND increases, after 60 min, the mortality rate increases., Antegrade Selective Cerebral Perfusion (ascp): At moderate hypothermia (25-28°C), ASCP should be performed at a pump flow rate of 10ml/kg/min, targeting a cerebral perfusion pressure of 50-60mmHg. Experimental data revealed that these conditions offer an optimal regional blood flow in the cortex (80±27ml/min/100g), the cerebellum (77±32ml/min/100g), the pons (89±5ml/min/100g) and the hippocampus (55±16ml/min/100g) for 25 minutes. If prolonged, does ASCP at 32°C provide the same neuroprotective effect?, Cannulation Strategy: Direct axillary artery cannulation ensures the advantage of performing both systemic cooling and ASCP through the same cannula, preventing additional manipulation with the attendant embolic risk. An additional cannulation of the left carotid artery ensures a bi-hemispheric perfusion, with a neurologic outcome of only 6% TND and 1% PND., Neuromonitoring: Near-infrared spectroscopy and evoked potentials may prove the effectiveness of the neuroprotective strategy used, especially if the trend goes to less radical cooling., Conclusion: A short interval of HCA (5 min) followed by a more extended period of ASCP (25 min) at moderate hypothermia (28°C), with a pump flow rate of 10ml/kg/min and a cerebral perfusion pressure of 50 mmHg, represents safe conditions for open arch surgery.