Robert M Brenner

Icahn School of Medicine at Mount Sinai, Manhattan, New York, United States

Are you Robert M Brenner?

Claim your profile

Publications (25)47.11 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Iatrogenic paraplegia has been accompanying cardiovascular surgery since its beginning. As a result, surgeons have been developing many theories about the exact mechanisms of this devastating complication. Thus, the impact of single arteries that contribute to the spinal perfusion is one of the most discussed subjects in modern surgery. The subsequent decision of reattachment or the permanent disconnection of these intercostal arteries divides the surgical community. On the one hand, the anatomical or vascular approach pleads for the immediate reimplantation to reconstruct the anatomical situation. On the other hand, the decision of the permanent disconnection aims at avoiding stealing phenomenon away from the spinal vascular network. This spinal collateral network can be described as consisting of three components-the intraspinal and two paraspinal compartments-that feed the nutrient arteries of the spinal cord. The exact functional impact of the different compartments of the collateral network remains poorly understood. In this review, the function of the intraspinal compartment in the context of collateral network principle as an immediate emergency backup system is described. The exact structure and architectural principles of the intraspinal compartment are described. The critical parameters with regard to the risk of postoperative spinal cord ischaemia are the number of anterior radiculomedullary arteries (ARMAs) and the distance between them in relation to the longitudinal extent of aortic disease. The paraspinal network as a sleeping reserve is proposed as the long-term backup system. This sleeping reserve has to be activated by arteriogenic stimuli. These are presented briefly, and prior findings regarding arteriogenesis are discussed in the light of the collateral network concept. Finally, the role of preoperative visualization of the ARMAs in order to evaluate the risk of postoperative paraplegia is emphasized.
    European journal of cardio-thoracic surgery: official journal of the European Association for Cardio-thoracic Surgery 09/2013; · 2.40 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Iatrogenic paraplegia has been accompanying cardiovascular surgery since its beginning. As a result, surgeons have been developing many theories about the exact mechanisms of this devastating complication. Thus, the impact of single arteries that contribute to the spinal per-fusion is one of the most discussed subjects in modern surgery. The subsequent decision of reattachment or the permanent disconnection of these intercostal arteries divides the surgical community. On the one hand, the anatomical or vascular approach pleads for the immedi-ate reimplantation to reconstruct the anatomical situation. On the other hand, the decision of the permanent disconnection aims at avoid-ing stealing phenomenon away from the spinal vascular network. This spinal collateral network can be described as consisting of three components—the intraspinal and two paraspinal compartments–that feed the nutrient arteries of the spinal cord. The exact functional impact of the different compartments of the collateral network remains poorly understood. In this review, the function of the intraspinal compartment in the context of collateral network principle as an immediate emergency backup system is described. The exact structure and architectural principles of the intraspinal compartment are described. The critical parameters with regard to the risk of postoperative spinal cord ischaemia are the number of anterior radiculomedullary arteries (ARMAs) and the distance between them in relation to the longitudinal extent of aortic disease. The paraspinal network as a sleeping reserve is proposed as the long-term backup system. This sleeping reserve has to be activated by arteriogenic stimuli. These are presented briefly, and prior findings regarding arteriogenesis are discussed in the light of the collateral network concept. Finally, the role of preoperative visualization of the ARMAs in order to evaluate the risk of post-operative paraplegia is emphasized.
    European Journal of Cardio-Thoracic Surgery 08/2013; · 2.67 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The spinal cord is particularly susceptible to ischaemic injury following repair of extensive descending thoracic and thoracoabdominal aortic aneurysms (TAAA). For the past decade, the Mount Sinai group in New York has intensively studied the anatomy of the extensive vascular network surrounding the spinal cord, as well as its dynamic morphology in response to decreased blood pressure and flow. Along with clinical data, experimental findings gave rise to the Collateral Network Concept, by which spinal cord injury in open TAAA repair can be significantly reduced. With the more recent widespread use of endovascular repair, strategies to prevent ischaemic spinal cord damage after extensive segmental artery sacrifice/occlusion are still evolving. The hypothesis that dividing extensive aneurysm repair into two steps may mitigate the impact of diminished blood flow to the collateral network has led to a recently conducted series of staged repair experiments. By exploiting the resources of the collater- al network, spinal cord injury could be minimised in staged open, as well as in staged hybrid repair and seems equally adoptable for endovascular procedures. The contribution presented herein provides an overview of clinical and experimental studies on the staged approach. Furthermore, it briefly assesses the anatomic rationale for the collateral network concept.
    Zentralblatt für Chirurgie 03/2013; 138:521-529. · 0.69 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The spinal cord is particularly susceptible to ischaemic injury following repair of extensive descending thoracic and thoracoabdominal aortic aneurysms (TAAA). For the past decade, the Mount Sinai group in New York has intensively studied the anatomy of the extensive vascular network surrounding the spinal cord, as well as its dynamic morphology in response to decreased blood pressure and flow. Along with clinical data, experimental findings gave rise to the Collateral Network Concept, by which spinal cord injury in open TAAA repair can be significantly reduced. With the more recent widespread use of endovascular repair, strategies to prevent ischaemic spinal cord damage after extensive segmental artery sacrifice/occlusion are still evolving. The hypothesis that dividing extensive aneurysm repair into two steps may mitigate the impact of diminished blood flow to the collateral network has led to a recently conducted series of staged repair experiments. By exploiting the resources of the collateral network, spinal cord injury could be minimised in staged open, as well as in staged hybrid repair and seems equally adoptable for endovascular procedures. The contribution presented herein provides an overview of clinical and experimental studies on the staged approach. Furthermore, it briefly assesses the anatomic rationale for the collateral network concept.
    Zentralblatt für Chirurgie 03/2013; · 0.69 Impact Factor
  • Annals of cardiothoracic surgery. 09/2012; 1(3):325-8.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To describe the histological findings in the aortic wall 5 days after thoracic endovascular aortic repair (TEVAR) in a porcine model. Two overlapping stent-grafts were implanted in each of 6 juvenile pigs, covering the entire descending thoracic aorta (DTA). On the 5(th) postoperative day, tissue samples were taken from the DTA in each animal. Medial thickness and medial necrosis were quantified and compared to measurements from the aortas of 6 control animals. Significant medial thinning was observed in stent-covered regions in the test animals. At the proximal landing zone, aortic wall thickness changed from 1387±68 to 782±74 µm within the covered aortic segment (p = 0.028); at the distal landing site, the wall thickness was 365±67 µm within the stent and 501±57 µm distally (p = 0.028). In the overlap zone, the aortic wall measured 524±122 vs. 1053±77 µm in native controls (p = 0.004). Aortic thickness proximal to the graft did not differ from the proximal region of native aortas (1468±96 vs. 1513±80 µm, p = 0.423), but the aorta was significantly thinner distal to the stent (707±38 vs. 815±52 µm, p = 0.004). Laminar necrosis constituted 38%±7% of the media in the proximal landing zone, 54%±4% in the overlap zone, and 46%±13% in the distal landing zone. In this porcine model, significant medial thinning and necrosis of the stented aorta was observed. The findings suggest an early phase of vulnerability of the aortic wall, before scarring and adaptive changes have strengthened the residual aorta.
    Journal of Endovascular Therapy 06/2012; 19(3):363-9. · 2.70 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In a porcine model, we investigated the impact of sudden stent graft occlusion of thoracic intercostal arteries after open lumbar segmental artery (SA) ligation. After randomization into two groups, 20 juvenile Yorkshire pigs (27.1±0.6 kg) underwent open lumbar SA sacrifice (T13-L5) followed by endovascular coverage of all thoracic SAs (T4-T12) at 32°C, either in a single operation (group 1) or in two stages separated by seven days (group 2). Collateral network pressure (CNP) was monitored by catheterization of the SA L1, and postoperative hind limb function was assessed using a modified Tarlov score. The CNP in group 1 decreased to 34% of baseline, whereas CNP after lumbar SA ligation in group 2 fell to 55% of baseline (74±2.4 to 25±3.6 mm Hg vs 74±4.5 to 41±5.5 mm Hg; p<0.0001). Subsequent thoracic stenting (group 2) led to another significant but milder drop (p=0.002 versus stage 1) from the restored CNP (71±4.2 to 54±4.9 mm Hg). Five of ten pigs in group 1 suffered paraplegia, in contrast to none in group 2 (median Tarlov score 6, vs 9; p=0.0031). Histopathologic analysis showed more severe ischemic damage to the lower thoracic (p=0.05) and lumbar spinal cord (p=0.002) in group 1. These results underline the potential of the staged approach in hybrid procedures. Furthermore they highlight the need for established adjuncts for preventing paraplegia in hybrid and pure stent-graft protocols in which sudden occlusion of multiple SAs occurs.
    The Annals of thoracic surgery 07/2011; 92(1):138-46; discussion 146. · 3.45 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Prevention of paraplegia after repair of thoracoabdominal aortic aneurysm requires understanding the anatomy and physiology of the spinal cord blood supply. Recent laboratory studies and clinical observations suggest that a robust collateral network must exist to explain preservation of spinal cord perfusion when segmental vessels are interrupted. An anatomic study was undertaken. Twelve juvenile Yorkshire pigs underwent aortic cannulation and infusion of a low-viscosity acrylic resin at physiologic pressures. After curing of the resin and digestion of all organic tissue, the anatomy of the blood supply to the spinal cord was studied grossly and with light and electron microscopy. All vascular structures at least 8 μm in diameter were preserved. Thoracic and lumbar segmental arteries give rise not only to the anterior spinal artery but to an extensive paraspinous network feeding the erector spinae, iliopsoas, and associated muscles. The anterior spinal artery, mean diameter 134 ± 20 μm, is connected at multiple points to repetitive circular epidural arteries with mean diameters of 150 ± 26 μm. The capacity of the paraspinous muscular network is 25-fold the capacity of the circular epidural arterial network and anterior spinal artery combined. Extensive arterial collateralization is apparent between the intraspinal and paraspinous networks, and within each network. Only 75% of all segmental arteries provide direct anterior spinal artery-supplying branches. The anterior spinal artery is only one component of an extensive paraspinous and intraspinal collateral vascular network. This network provides an anatomic explanation of the physiological resiliency of spinal cord perfusion when segmental arteries are sacrificed during thoracoabdominal aortic aneurysm repair.
    The Journal of thoracic and cardiovascular surgery 04/2011; 141(4):1020-8. · 3.41 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A comprehensive strategy to prevent paraplegia after open surgical or endovascular repair of thoracoabdominal aortic aneurysms requires a thorough understanding of the response of the collateral network to extensive segmental artery sacrifice. Ten Yorkshire pigs underwent perfusion with a low-viscosity acrylic resin. With the use of cardiopulmonary bypass, 2 animals each were perfused in the native state and immediately, 6 hours, 24 hours, and 5 days after sacrifice of all segmental arteries (T4-L5). After digestion of surrounding tissue, the vascular cast of the collateral network underwent analysis of arterial and arteriolar diameters and the density and spatial orientation of the vasculature using light and scanning electron microscopy. Within 24 hours, the diameter of the anterior spinal artery had increased significantly, and within 5 days the anterior spinal artery and the epidural arterial network had enlarged in diameter by 80% to 100% (P < .0001). By 5 days, the density of the intramuscular paraspinous vessels had increased (P < .0001), a shift of size distribution from small to larger arterioles was seen (P = .0002), and a significant realignment of arterioles parallel to the spinal cord had occurred (P = .0005). Within 5 days after segmental artery occlusion, profound anatomic alterations in the intraspinal and paraspinous arteries and arterioles occurred, providing the anatomic substrate for preservation of spinal cord blood flow via collateral pathways.
    The Journal of thoracic and cardiovascular surgery 04/2011; 141(4):1029-36. · 3.41 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Bicuspid aortic valves (BAV) are frequently associated with root/ascending aorta dilatation, but there is controversy regarding when to operate to prevent dissection of a dilated aorta associated with a well-functioning BAV. From 1988 through 2008, 158 patients (mean age: 56 ± 13.5 years) with a dilated ascending aorta (AA) and a well-functioning BAV were referred to our institution. All patients underwent computed tomographic (CT) scanning and digitization to calculate mean AA diameter. Forty-two patients underwent operation a median of 52 days after initial CT scan with a mean AA diameter of 5.6 ± 0.5 cm. One hundred sixteen patients (mean diameter 4.6 ± 0.5 cm) were enrolled in annual or semiannual surveillance. Seventy-one patients, 45 with 2 or more CT scans, are still under surveillance. Average follow-up was 6.5 ± 4.1 years. Overall survival after the first encounter was 93% at 5 years and 85% at 10 years. A total of 87 of 158 patients had a Bentall or Yacoub procedure, with two hospital deaths (2.3%). Mean duration of surveillance in the 116 patients without immediate operation was 4.2 ± 2.9 years (481 patient-years). Average growth rate of the AA in patients with 2 scans or greater was 0.77 mm/year (p < 0.0001 versus normal population) with no significant impact of hypertension, sex, smoking or age. Forty-five of the 116 surveillance patients underwent operation after a mean of 3.4 ± 2.9 years (mean age 55 ± 14.7 years; mean AA diameter 4.9 ± 0.6 cm). Six patients died without surgery, median age 82 (range, 44 to 87) years, but none within one year of the last CT scan. A consistent approach to patients with a well-functioning BAV and AA dilatation, recommending operation to those with an AA diameter greater than 5 cm and deferring operation in patients under surveillance in the absence of significant enlargement (>0.5 cm/year), resulted in overall survival equivalent to a normal age-matched and sex-matched population. Operation was necessary in approximately 10% of patients under surveillance each year.
    The Annals of thoracic surgery 12/2010; 90(6):1884-90; discussion 1891-2. · 3.45 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We describe the long-term results of aortic arch replacement using a trifurcated graft, including an assessment of survival, neurologic complications, and graft patency. A retrospective review was conducted on data from 206 consecutive patients (125 male; median age, 67 years; range, 20-87 years) who had a trifurcated graft used for aortic arch replacement between September 1999 and September 2009. Seventy-four patients (35.9%) had chronic dissection, 68 patients (33.0%) had atherosclerotic aneurysms, and 39 patients (18.9%) had degenerative disease. Ninety-one patients (44.2%) had undergone previous cardiac surgery. An elephant trunk was placed in 190 patients (92.2%) and completed in 101 patients (53.1%), with an interval of less than 365 days between stages in 94 of 101 patients. Hospital mortality was 6.8% (14/206). Adverse outcome (death/stroke within the first year postoperatively) occurred in 27.7% of patients (57/206; 50 deaths/7 strokes). Among 152 1-year survivors, the annual rates of transient ischemic attack and stroke were 0.85% and 1.1%, respectively. At 6 years, 75% of patients were still alive, compared with 92% in a matched New York State control population (P < .001). Follow-up computed tomography scans (189 studies in 176/206 patients [85.4%]) revealed 100% patency of the trifurcated graft limbs at a mean of 2.3 years. Aortic arch replacement using a trifurcated graft is highly durable, with excellent patency in the branch grafts, and is associated with a low incidence of cerebral embolization. However, the long-term outcome in these patients is compromised by extensive comorbidities.
    The Journal of thoracic and cardiovascular surgery 12/2010; 140(6 Suppl):S71-6; discussion S86-91. · 3.41 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We compared aortic root reconstructions using conduits with biological valves and mechanical valves. Of 597 patients (1995-2008), 307 (mean age 71 years [23-89 years]) had biological valves and 290 (mean age 51 years [21-82 years]) had mechanical valves. The subgroup of 242 patients aged 50 to 70 years included 133 with biological and 109 with mechanical valves. Overall hospital mortality was 3.9% with biological valves (n = 15; elective: 3.7% [n = 10]) versus 2.8% with mechanical valves (n = 8; elective: 1.4% [n = 3]). In patients 50 to 70 years, age greater than 65 years (relative risk: 3.3 [P = .0001]), clot (relative risk: 2.5 [P = .05]), coronary artery disease (relative risk:3.5 [P < .0001]), and degenerative etiology (relative risk: 0.4 [P = .006]) were independent risk factors for long-term survival (after postoperative day 30); there was no difference in long-term survival between biological and mechanical valves (relative risk: 0.9 [P = .74]). The linearized rate for valve/ascending aorta reoperation was 0.86%/pt-y (2 in 2310 pt-y) after mechanical valves and 2.5%/pt-y (4 in 1586 pt-y) after Bentall procedures with the biological valve. The choice of valve for aortic root reconstruction seems to have no influence on long-term outcome. Emergency operation and the presence of clot/atheroma have a significant impact on short-term outcome. Reoperation for either ascending aorta and/or aortic valve is low.
    The Journal of thoracic and cardiovascular surgery 12/2010; 140(6 Suppl):S64-70; discussion S86-91. · 3.41 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Endovascular repair of descending thoracic and thoracoabdominal aortic aneurysms is an appealing alternative to the standard surgical approach, but precludes revascularization of segmental arteries (SAs). For safer surgical and endovascular repairs, an accurate prediction of the risk of paraplegia in relation to the extent of SA sacrifice is needed. From January 1994 to October 2008, 609 patients (mean age, 63 ± 14 years) underwent surgical descending thoracic or thoracoabdominal aortic aneurysm repair without SA reimplantation. Three hundred seventy-six patients (62%) were male; 159 (26%) had urgent or emergent operation; 199 (33%) had previous aortic surgery. Somatosensory- or motor-evoked potential monitoring and cerebrospinal fluid drainage were routinely performed. Hospital mortality was 10.7% (65 patients). Spinal cord injury (SCI) occurred in 3.4% (21 patients). The extent of resection-expressed as the number of SAs sacrificed (p = 0.007)-and the need for visceral artery reimplantation (p = 0.03) were independent risk factors for paraplegia. Further analysis identified four risk groups (p < 0.0001): fewer than 8 SAs sacrificed (group A, SCI = 1.2%); sacrifice of 8 to 12 SAs with proximal origin in the upper thorax (group B, SCI = 3.7%); 8 to 12 SAs sacrificed beginning in the lower thorax (group C, SCI = 15.4%); and 13 or more SAs sacrificed (group D, SCI = 12.5%). This four-group model more accurately predicts SCI risk than the Crawford classification (goodness of fit c statistic: 0.748 versus 0.640). The extent of SA sacrifice is the most powerful predictor of paraplegia risk. For aneurysms of moderate extent, a more distal location involving the abdominal aorta increases the risk of spinal cord injury. Sacrifice of fewer than 8 SAs is associated with a very low paraplegia risk regardless of location.
    The Annals of thoracic surgery 10/2010; 90(4):1237-44; discussion 1245. · 3.45 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In a pig model, we compared spinal cord injury after extensive segmental artery (SA) sacrifice in a single stage with recovery after a two-stage procedure: lumbar artery followed by thoracic SA sacrifice. Twenty juvenile Yorkshire pigs were randomly assigned to undergo extensive SA sacrifice at 32 degrees C in a single operation (group 1, n = 10), or thoracic SA ligation 7 days after lumbar artery sacrifice (group 2, n = 10). Spinal cord perfusion pressure (SCPP) was monitored using a catheter placed in the distal stump of L1. Hind limb function was evaluated intraoperatively using motor-evoked potentials and for 5 days postoperatively using a modified Tarlov score. Motor-evoked potentials were intact in all pigs until 1 hour after surgery. All pigs in group 2 fully recovered hind limb function, whereas 40% in group 1 experienced paraplegia (median Tarlov scores 9 versus 7; p = 0.004). Group 1 SCPP fell to 28 +/- 6 mm Hg after SA sacrifice, compared with 44 +/- 8 mm Hg in group 2 (p < 0.0001). After sacrifice of all residual SAs, SCPP in group 2 remained consistently greater than 85% of baseline, significantly higher than group 1 SCPP from end clamping until 72 hours (p = 0.0002). Histopathologic analysis showed more severe ischemic damage to the lower thoracic (p < 0.001) and lumbar spinal cord (p = 0.01) in group 1. In contrast with the single-stage approach, a two-stage procedure, starting with ligation of six or fewer lumbar SAs, leads to only a mild drop in SCPP and stimulates vascular remodeling, minimizing the impact of subsequent SA sacrifice on spinal cord function. The greater safety of extensive SA sacrifice when undertaken in two stages has important implications for endovascular and hybrid aneurysm repair.
    The Annals of thoracic surgery 09/2010; 90(3):722-9. · 3.45 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: a Objective: Prevention of paraplegia after repair of thoracoabdominal aortic aneurysm requires understanding the anatomy and physiology of the spinal cord blood supply. Recent laboratory studies and clinical observations sug-gest that a robust collateral network must exist to explain preservation of spinal cord perfusion when segmental vessels are interrupted. An anatomic study was undertaken. Methods: Twelve juvenile Yorkshire pigs underwent aortic cannulation and infusion of a low-viscosity acrylic resin at physiologic pressures. After curing of the resin and digestion of all organic tissue, the anatomy of the blood supply to the spinal cord was studied grossly and with light and electron microscopy. Results: All vascular structures at least 8 mm in diameter were preserved. Thoracic and lumbar segmental arteries give rise not only to the anterior spinal artery but to an extensive paraspinous network feeding the erector spinae, iliopsoas, and associated muscles. The anterior spinal artery, mean diameter 134 AE 20 mm, is connected at mul-tiple points to repetitive circular epidural arteries with mean diameters of 150 AE 26 mm. The capacity of the para-spinous muscular network is 25-fold the capacity of the circular epidural arterial network and anterior spinal artery combined. Extensive arterial collateralization is apparent between the intraspinal and paraspinous networks, and within each network. Only 75% of all segmental arteries provide direct anterior spinal artery–supplying branches. Conclusions: The anterior spinal artery is only one component of an extensive paraspinous and intraspinal col-lateral vascular network. This network provides an anatomic explanation of the physiological resiliency of spinal cord perfusion when segmental arteries are sacrificed during thoracoabdominal aortic aneurysm repair. (J Thorac Cardiovasc Surg 2011;141:1020-8) A thorough understanding of the anatomy of the blood supply of the spinal cord appears essential for developing optimal strategies to prevent spinal cord injury during and after open surgical or endovascular repair of extensive thoracic and thoracoabdominal aortic aneurysms (TAAAs). Direct vi-sualization of these vessels is difficult clinically, 1-5 however, and most surgeons therefore continue to rely on descriptions of the spinal cord circulation derived from a few classic anatomic studies. 6-8 The most influential of these has been the treatise by Albert W. Adamkiewicz (1850–1921), whose meticulously detailed and beautiful drawings suggest that the most important input into the anterior spinal artery (ASA) is a single dominant branch of a segmental artery (SA) in the lower thoracic or upper lumbar region with a characteristic hairpin turn, which is now often referred to as the artery of Adamkiewicz.
    Journal of Thoracic and Cardiovascular Surgery 06/2010; · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: a Objective: A comprehensive strategy to prevent paraplegia after open surgical or endovascular repair of thora-coabdominal aortic aneurysms requires a thorough understanding of the response of the collateral network to extensive segmental artery sacrifice. Methods: Ten Yorkshire pigs underwent perfusion with a low-viscosity acrylic resin. With the use of cardiopul-monary bypass, 2 animals each were perfused in the native state and immediately, 6 hours, 24 hours, and 5 days after sacrifice of all segmental arteries (T4–L5). After digestion of surrounding tissue, the vascular cast of the collateral network underwent analysis of arterial and arteriolar diameters and the density and spatial orientation of the vasculature using light and scanning electron microscopy. Results: Within 24 hours, the diameter of the anterior spinal artery had increased significantly, and within 5 days the anterior spinal artery and the epidural arterial network had enlarged in diameter by 80% to 100% (P<.0001). By 5 days, the density of the intramuscular paraspinous vessels had increased (P <.0001), a shift of size distri-bution from small to larger arterioles was seen (P ¼ .0002), and a significant realignment of arterioles parallel to the spinal cord had occurred (P ¼ .0005). Conclusions: Within 5 days after segmental artery occlusion, profound anatomic alterations in the intraspinal and paraspinous arteries and arterioles occurred, providing the anatomic substrate for preservation of spinal cord blood flow via collateral pathways. (J Thorac Cardiovasc Surg 2011;141:1029-36)
    Journal of Thoracic and Cardiovascular Surgery 06/2010; · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The optimal treatment of chronic distal aortic dissection remains controversial, with endovascular stent-graft techniques challenging traditional surgery. From January 1994 to April 2007, 104 patients (82 male, median age 60.5 years) with chronic distal aortic dissection underwent surgical repair, 0 to 21 years after initial diagnosis of acute type A or B dissection (median 2.1 years). Twenty-three (22%) patients underwent urgent-emergent surgery. Mean aortic diameter was 6.9 +/- 1.4 cm. Indications for surgery, other than aortic expansion, were pain in 6 (6%) patients, malperfusion in 6 (6%), and rupture in 11 (11%). Forty-nine (47%) had previous cardioaortic surgery (29% dissection-related), 21 (20%) had coronary artery disease, 12 (12%) had Marfan syndrome, and 4 (4%) were on chronic dialysis. Twenty-six (25%) had a thrombosed false lumen. Thirty (29%) patients required reimplantation of visceral arteries; 8.3 +/- 2.7 segmental artery pairs were sacrificed. Hospital mortality was 9.6% (10 patients). Paraplegia occurred in 5 (4.8%). Twenty-seven patients (26%) experienced adverse outcome (death within one year, paraplegia, stroke, or dialysis). Adverse outcome was associated with atheroma (p = 0.04, odds ratio = 4.3). Survival was 78% at 1, 68% at 5, and 59% at 10 years (average follow-up, 7.7 +/- 4.1 years). Freedom from distal aortic reoperation was 99% at 1, 93% at 5, and 83% at 10 years. After one year, patients enjoyed longevity equivalent to a normal age-sex matched population (standardized mortality ratio = 1.38, p = 0.23). By multivariate analysis, atheroma (p = 0.0005, relative risk = 9.32) and age (p = 0.0003, relative risk = 1.15/year) were risk factors for long-term survival. The efficacy of open repair for distal chronic dissection is highlighted by normal survival after the first year, and a low reoperation-reintervention rate.
    The Annals of thoracic surgery 05/2010; 89(5):1458-66. · 3.45 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: There are no effective preventive measures to avoid paraplegia after interruption of segmental inflow to the spinal cord in aortic surgical procedures. Thus, the future clinical success of endovascular and hybrid procedures for the treatment of extensive aortic pathology requires the development of strategies for reliable neuroprotection after segmental artery occlusion. Basic pathophysiologic questions concerning spinal collateralization have still not been answered. Which mechanisms contribute to the ability of spinal collateral networks to re-establish preoperative spinal perfusion pressures in the early post-operative period? Are these mechanisms useful to develop new approaches for prophylactic protection of the spinal cord? This article demonstrates functional and anatomical principles of spinal collateralization, and discusses arteriogenesis as a new and poorly investigated option to achieve prophylactic protection of the spinal cord.
    Zeitschrift für Herz- Thorax- und Gefäßchirurgie 01/2010;
  • Thoracic and Cardiovascular Surgeon - THORAC CARDIOVASC SURG. 01/2010; 58.
  • Thoracic and Cardiovascular Surgeon - THORAC CARDIOVASC SURG. 01/2010; 58.

Publication Stats

143 Citations
47.11 Total Impact Points

Institutions

  • 2010–2013
    • Icahn School of Medicine at Mount Sinai
      • Department of Cardiothoracic Surgery
      Manhattan, New York, United States
  • 2012
    • Universität Heidelberg
      Heidelburg, Baden-Württemberg, Germany