Alberto Pochettino

Deep hypothermic circulatory arrest: I. Effects of cooling on electroencephalogram and evoked potentials

BACKGROUND Deep hypothermia is an important cerebral protectant and is critical in procedures requiring circulatory arrest. The purpose of this study was to determine the factors that influence the neurophysiologic changes during cooling before circulatory arrest, in particular the occurrence of electrocerebral silence. METHODS In 109 patients undergoing hypothermic circulatory arrest with neurophysiologic monitoring, five electrophysiologic events were selected for detailed study. RESULTS The mean nasopharyngeal temperature when periodic complexes appeared in the electroencephalogram after cooling was 29.6 degrees C +/- 3 degrees C, electroencephalogram burst-suppression appeared at 24.4 degrees C +/- 4 degrees C, and electrocerebral silence appeared at 17.8 degrees C +/- 4 degrees C. The N20-P22 complex of the somatosensory evoked response disappeared at 21.4 degrees C +/- 4 degrees C, and the somatosensory evoked response N13 wave disappeared at 17.3 degrees C +/- 4 degrees C. The temperatures of these various events were not significantly affected by any patient-specific or surgical variables, although the time to cool to electrocerebral silence was prolonged by high hemoglobin concentrations, low arterial partial pressure of carbon dioxide, and by slow cooling rates. Only 60% of patients demonstrated electrocerebral silence by either a nasopharyngeal temperature of 18 degrees C or a cooling time of 30 minutes. CONCLUSIONS With the high degree of interpatient variability in these neurophysiologic measures, the only absolute predictors of electrocerebral silence were nasopharyngeal temperature below 12.5 degrees C and cooling longer than 50 minutes.

New Paradigms and Improved Results for the Surgical Treatment of Acute Type A Dissection

ObjectiveTo examine the effect of an integrated surgical approach to the treatment of acute type A dissections. Summary Background DataAcute type A dissection requires surgery to prevent death from proximal aortic rupture or malperfusion. Most series of the past decade have reported a death rate in the range of 15% to 30%. MethodsFrom January 1994 to March 2001, 104 consecutive patients underwent repair of acute type A dissection. All had an integrated operative management as follows: intraoperative transesophageal echocardiography; hypothermic circulatory arrest (HCA) with retrograde cerebral perfusion (RCP) to replace the aortic arch; HCA established after 5 minutes of electroencephalographic (EEG) silence in neuromonitored patients (66%) or after 45 minutes of cooling in patients who were not neuromonitored (34%); reinforcement of the residual arch tissue with a Teflon felt “neo-media”; cannulation of the arch graft to reestablish cardiopulmonary bypass at the completion of HCA (antegrade graft perfusion); and remodeling of the sinus of Valsalva segments with Teflon felt “neo-media” and aortic valve resuspension (78%) or replacement with a biologic or mechanical valved conduit (22%). ResultsMean age was 59 ± 15 (range 22–86) years, with 71% men and 13% redo sternotomy after a previous cardiac procedure. Mean cardiopulmonary bypass time was 196 ± 50 minutes. Mean HCA with RCP time was 42 ± 12 minutes (range 19–84). Mean cardiac ischemic time was 140 ± 45 minutes. Eleven percent of patients presented with a preoperative neurologic deficit, and 5% developed a new cerebrovascular accident after dissection repair. The in-hospital death rate was 9%. Excluding the patients who presented neurologically unresponsive or with ongoing cardiopulmonary resuscitation (n = 5), the death rate was 4%. In six patients adverse cerebral outcomes were potentially avoided when immediate surgical fenestration was prompted by a sudden change in the EEG during cooling. Forty-five percent of neuromonitored patients required greater than 30 minutes to achieve EEG silence. ConclusionThe authors have shown that the surgical integration of sinus segment repair or aortic root replacement, the use of EEG monitoring, partial or total arch replacement using RCP, routine antegrade graft perfusion, and the uniform use of transesophageal echocardiography substantially decrease the death and complication rates of acute type A dissection repair.

Have hybrid procedures replaced open aortic arch reconstruction in high-risk patients? A comparative study of elective open arch debranching with endovascular stent graft placement and conventional elective open total and distal aortic arch reconstruction

OBJECTIVE Open total arch procedures have been associated with significant morbidity and mortality in patients with multiple comorbidities. Aortic arch debranching with endovascular graft placement, the hybrid arch procedure, has emerged as a surgical option in this patient population. This study evaluates the outcomes of a contemporary comparative series from one institution of open total arch and hybrid arch procedures for extensive aortic arch pathology. METHODS From July 2000 to March 2009, 1196 open arch procedures were performed, including 45 elective and 7 emergency open total arch procedures. From 2005 to 2009, 64 hybrid arch procedures were performed: 37 emergency type A dissections and 27 elective open arch debranchings. Hemiarch procedures were excluded. RESULTS The hybrid arch cohort was significantly older (P = .008) and had greater predominance of atherosclerotic pathophysiology (P < .001). The incidence of permanent cerebral neurologic deficit was similar at 4% (1/27) for the hybrid arch cohort and 9% (4/45) for the open aortic arch cohort. In-hospital mortality was similar at 11% (3/27) for the hybrid arch cohort and 16% (7/45) for the open aortic arch cohort. However, in the open arch group, there was a significant difference in mortality between patients aged less than 75 years at 9% (3/34) and patients aged more than 75 years at 36% (4/11) (P = .05). CONCLUSIONS Hybrid arch procedures provide a safe alternative to open repair. This study suggests the hybrid arch approach has a lower mortality for high-risk patients aged more than 75 years. This extends the indication for the hybrid arch approach in patients with complex aortic arch pathology previously considered prohibitively high risk for conventional open total arch repair.

Risk factors, outcomes, and clinical manifestations of spinal cord ischemia following thoracic endovascular aortic repair

OBJECTIVE The purpose of this study was to assess the incidence, risk factors, and clinical manifestations of spinal cord ischemia (SCI) after thoracic endovascular aortic repair (TEVAR). METHODS A retrospective review of a prospectively collected database was performed for all patients undergoing TEVAR at a single academic institution between July 2002 and June 2010. Preoperative demographics, procedure-related variables, and clinical details related to SCI were examined. Logistic regression analysis was performed to identify risk factors for the development of SCI. RESULTS Of the 424 patients who underwent TEVAR during the study period, 12 patients (2.8%) developed SCI. Mean age of this cohort with SCI was 69.6 years (range, 44-84 years), and 7 were women. One-half of these patients had prior open or endovascular aortic repair. Indication for surgery was either degenerative aneurysm (n = 8) or dissection (n = 4). Six TEVARs were performed electively, with the remaining done either urgently or emergently due to contained rupture (n = 2), dissection with malperfusion (n = 2), or severe back pain (n = 2). All 12 patients underwent extent C endovascular coverage. Multivariate regression analysis demonstrated chronic renal insufficiency to be independently associated with SCI (odds ratio [OR], 4.39; 95% confidence interval [CI], 1.2-16.6; P = .029). Onset of SCI occurred at a median of 10.6 hours (range, 0-229 hours) postprocedure and was delayed in 83% (n = 10) of patients. Clinical manifestations of SCI included lower extremity paraparesis in 9 patients and paraplegia in 3 patients. At SCI onset, average mean arterial pressure (MAP) and lumbar cerebrospinal fluid (CSF) pressure was 77 mm Hg and 10 mm Hg, respectively. Therapeutic interventions increased blood pressure to a significantly higher average MAP of 99 mm Hg (P = .001) and decreased lumbar CSF pressure to a mean of 7 mm Hg (P = .30) at the time of neurologic recovery. Thirty-day mortality was 8% (1 of 12 patients). The single patient who expired, never recovered any lower extremity neurologic function. All patients surviving to discharge experienced either complete (n = 9) or incomplete (n = 2) neurologic recovery. At mean follow-up of 49 months, 7 of 9 patients currently alive continued to exhibit complete, sustained neurologic recovery. CONCLUSION Spinal cord ischemia after TEVAR is an uncommon, but important complication. Preoperative renal insufficiency was identified as a risk factor for the development of SCI. Early detection and treatment of SCI with blood pressure augmentation alone or in combination with CSF drainage was effective in most patients, with the majority achieving complete, long-term neurologic recovery.

Targeting Landing Zone 0 by Total Arch Rerouting and TEVAR: Midterm Results of a Transcontinental Registry

BACKGROUND Landing zone 0, defined as a proximal landing zone in the ascending aorta, remains the last frontier to be taken. Midterm results of total arch rerouting and thoracic endovascular aortic repair (TEVAR) extending into landing zone 0 remain to be determined. METHODS From 2003 to 2011, 66 patients (mean age, 70 years; 68% men) presenting with pathologic conditions affecting the aortic arch (atherosclerotic aneurysms [n = 48], penetrating ulcers [n = 6], type B dissections [n = 6], type B after type A dissections [n = 5], and anastomotic aneurysm [n = 1]) were treated in 5 participating centers. Of these 66 patients, only 12% would have been deemed suitable for any kind of conventional surgical repair because of multisegmental aortic disease or comorbidities. RESULTS In-hospital mortality was 9%. Retrograde type A dissection was observed in 3% of patients. The assisted type I and type III endoleak rate was 0%. Stroke was seen in 5% of patients. Permanent paraplegia was observed in 3% of those studied. Median follow-up was 25 months (8-41 months). There was 1 late type Ib endoleak, which was followed by watchful waiting. Five-year survival was 72%. Five-year aorta-related survival was 96%. No aorta-related reintervention had to be performed in the segments treated. CONCLUSIONS Midterm results of total arch rerouting and TEVAR extending into landing zone 0 are excellent in regard to aorta-related survival and freedom from aorta-related reintervention. Retrograde type A dissection, potentially related to compliance mismatch between the ascending aorta and the stent-graft, warrants further attention. Extended application of this strategy augments therapeutic options in a group of patients who are not suitable candidates for conventional therapy.

Deep hypothermic circulatory arrest: II. Changes in electroencephalogram and evoked potentials during rewarming.

BACKGROUND Electrophysiologic studies during rewarming after deep hypothermic circulatory arrest probe the state of the brain during this critical period and may provide insight into the neurological effects of circulatory arrest and the neurologic outcome. METHODS Electroencephalogram (EEG) and evoked potentials were monitored during rewarming in 109 patients undergoing aortic surgery with hypothermic circulatory arrest. RESULTS The sequence of neurophysiologic events during rewarming did not mirror the events during cooling. The evoked potentials recovered first followed by EEG burst-suppression and then continuous EEG. The time to recovery of the evoked potentials N20-P22 complex was significantly correlated with the time of circulatory arrest even in patients without postoperative neurologic deficits (r = 0.37, (p = 0.002). The nasopharyngeal temperatures at which continuous EEG activity and the N20-P22 complex returned were strongly correlated (r = 0.44, p = 0.0002; r = 0.41, p = 0.00003) with postoperative neurologic impairment. Specifically, the relative risk for postoperative neurologic impairment increased by a factor of 1.56 (95% CI 1.1 to 2.2) for every degree increase in temperature at which the EEG first became continuous. CONCLUSIONS No trend toward shortened recovery times or improved neurologic outcome was noted with lower temperatures at circulatory arrest, indicating that the process of cooling to electrocerebral silence produced a relatively uniform degree of cerebral protection, independent of the actual nasopharyngeal temperature.

Long-term comparison of thoracic endovascular aortic repair (TEVAR) to open surgery for the treatment of thoracic aortic aneurysms

OBJECTIVE Thoracic endovascular aortic repair (TEVAR) has become a widely established treatment for a variety of thoracic aortic pathologic diseases despite limited long-term data to support its use. We compared the long-term outcomes of TEVAR with the 3 commercially available stents grafts for thoracic aortic aneurysms to results in control subjects undergoing open surgery. METHODS Demographic, clinical radiographic parameters were collected prospectively on patients enrolled in trials assessing the Gore TAG (55), Medtronic Talent (36) and Cook TX2 (15) devices. Outcomes were compared with 45 contemporaneous open controls. Detailed clinical and radiographic information was available for analysis. Standard univariate, survival, and regression methods were used. RESULTS During the study period (1995-2007) 106 patients were enrolled in TEVAR trials and there were 45 open controls. TEVAR patients were older and had significantly more comorbidities including diabetes and renal failure. TEVAR patients had 2.3 ± 1.3 devices implanted. Mortality (2.6% TEVAR, 6.7% open; P = .1), paralysis/paraparesis (3.9% TEVAR, 7.1% open; P = .2), and prolonged intubation more than 24 hours (9% TEVAR, 24% open; P = .02) tended to be more common in the open controls. Overall survival at 10 years was similar between groups (log rank P = .5). Multivariate predictors of late mortality included age, chronic obstructive pulmonary disease, diabetes, and chronic renal failure. Use of TEVAR versus open surgery did not influence mortality (hazard ratio, 0.9 95% confidence interval, 0.4-1.6). Over 5 years of radiographic follow-up in the TEVAR group, mean aortic diameter decreased from 61 to 55 mm. Freedom from reintervention on the treated segment was 85% in TEVAR patients at 10 years. CONCLUSIONS TEVAR is a safe and effective procedure to treat thoracic aortic aneurysms with improved perioperative and similar long-term results as open thoracic aortic repair. TEVAR-treated aneurysm diameters initially decrease and then stabilize over time.

Risk factors for early primary graft dysfunction after lung transplantation: a registry study.

Abstract:  Background:  Primary graft dysfunction (PGD) is a leading cause of early morbidity and mortality in lung transplantation. We sought to identify risk factors for PGD using the United Network for Organ Sharing/International Society for Heart and Lung Transplant (UNOS/ISHLT) Registry.

Retrograde and antegrade cerebral perfusion: results in short elective arch reconstructive times.

BACKGROUND Debate remains regarding optimal cerebral circulatory management during relatively noncomplex, short arch reconstructive times. Both retrograde cerebral perfusion with deep hypothermic circulatory arrest (RCP/DHCA) and antegrade cerebral perfusion with moderate hypothermic circulatory arrest (ACP/MHCA) have emerged as established techniques. The aim of the study was to evaluate perioperative outcomes between antegrade and retrograde cerebral perfusion techniques for elective arch reconstruction times less than 45 minutes. METHODS Between 1997 and September 2008, 776 cases from two institutions were reviewed to compare RCP/DHCA and ACP/MHCA perfusion techniques. At the University of Pennsylvania, 682 were treated utilizing RCP/DHCA cerebral protection. At the University of Bologna, 94 were treated with ACP/MHCA and bilateral cerebral perfusion. RESULTS Mean cerebral ischemic time and visceral ischemic time differed between RCP/DHCA and ACP/MHCA (p < 0.001). Multivariate analysis showed age more than 65 years, atherosclerotic aneurysm, and cross-clamp time as predictors of the composite endpoint of mortality, neurologic event, and acute myocardial infarction. There was no significant difference in permanent neurologic deficit, temporary neurologic dysfunction, or renal failure, between RCP/DHCA and ACP/MHCA. Mortality was comparable across both techniques. CONCLUSIONS Both RCP/DHCA and ACP/MHCA have emerged as effective techniques for selected aortic arch operations with low morbidity and mortality. Univariate analysis revealed no statistically significant differences in primary or secondary outcomes between techniques for aortic reconstruction times less than 45 minutes. Data from this study demonstrate that selective use of either RCP/DHCA or ACP/MHCA provides excellent cerebral and visceral outcomes for elective open aortic surgery with short arch reconstructive times.

Classic hybrid evolving approach to distal arch aneurysms: Toward the zone zero solution

BACKGROUND A combined open surgical and endovascular approach to managing aneurysms of the distal aortic arch (hybrid arch repair) is evolving as a viable treatment option. Our aim is to describe a treatment strategy in high-risk patients and report the technical and clinical success of the hybrid approach to aneurysms involving the distal aortic arch. METHODS From July 2005 until December 2009, 27 consecutive patients with aneurysms of the distal aortic arch were treated via a hybrid arch repair. Of this group, 23 patients underwent aortic arch debranching and revascularization before endovascular stent deployment in the ascending aorta (type I). Four patients required ascending aortic and transverse arch replacement before stent graft deployment (type II). RESULTS A stent graft was successfully deployed in 100% of patients after aortic arch vessel debranching via median sternotomy. The mean age of the patients was 71 ± 7.5 years. The average cardiopulmonary bypass time was 199 ± 84 minutes with an average crossclamp time of 57 ± 53 minutes. Deep hypothermic circulatory arrest was required in 4 patients (all type II). The average length of stay was 17.2 ± 14 days. The complications included stroke in 3 (11%) patients, permanent paralysis in 2 (7%), and perioperative death in 3 (11%) patients. CONCLUSIONS Early results of type I and II hybrid arch repair, in this cohort of patients with mutiple comorbid risk factors, are acceptable and even encouraging. This evolving approach to aneurysms involving the aortic arch may extend the indications for use of endovascular prostheses in the treatment of patients with complex aortic arch disease.