Maximilian Luehr

Paraplegia after extensive thoracic and thoracoabdominal aortic aneurysm repair: Does critical spinal cord ischemia occur postoperatively?

OBJECTIVE Spinal cord injury can occur not only during extensive thoracoabdominal aneurysm repair but also postoperatively, causing delayed-onset paraplegia. METHODS A series of 858 thoracoabdominal aneurysm repairs (June 1990-June 2006) with an overall paraplegia rate of 2.7% was analyzed retrospectively. Serial segmental artery sacrifice was monitored by using somatosensory evoked potentials; segmental arteries were not reimplanted. Of a total of 20 cases of paraplegia, 3 occurred intraoperatively and 7 occurred late postoperatively: these will not be analyzed further. In 10 cases (the paraplegia group) spinal cord injury occurred within 48 hours after thoracoabdominal aneurysm repair, despite intact somatosensory evoked potentials at the end of the procedure. These patients with early postoperative delayed paraplegia were compared with 10 matched control subjects who recovered without spinal cord injury. RESULTS In the paraplegia group a median of 9 segmental arteries (range, 5-12 segmental arteries) were sacrificed. There were 9 male subjects: median age was 63 years (range, 40-79 years), and 4 of 10 had cerebrospinal fluid drainage. A median of 9 segmental arteries (range, 2-12 segmental arteries) were also sacrificed in the matched recovery group. There were 4 male subjects; median age was 66 years (range, 40-78 years), and 8 of 10 had cerebrospinal fluid drainage. During the first 48 hours postoperatively, there were no significant differences in arterial and mixed venous oxygen saturation, partial arterial O2 and CO2 pressures, body temperature, glucose, hematocrit, or pH. The mean central venous pressures, however, were significantly higher in the paraplegic patients from 1 to 5 hours postoperatively (P = .03). In addition, although absolute mean aortic pressures did not differ between matched pairs postoperatively, when pressures were considered as a percentage of individual antecedent preoperative mean aortic pressure, paraplegic patients had significantly lower values during the first 5 hours postoperatively (P = .03). CONCLUSIONS This study suggests that paraplegia can result from inadequate postoperative spinal cord perfusion caused by relatively minor differences from control subjects in perfusion parameters. Delayed paraplegia can perhaps be prevented with better hemodynamic and fluid management.

Staged repair of thoracic and thoracoabdominal aortic aneurysms using the elephant trunk technique: a consecutive series of 215 first stage and 120 complete repairs

OBJECTIVES Repair of thoracic aneurysms (TA) involving the ascending, arch, and descending aorta results in substantial morbidity and mortality. This study evaluates outcomes with a two-stage elephant trunk (ET) technique. METHODS Two hundred and fifteen consecutive patients (pts) underwent total arch replacement using an ET (02/90-09/06). One hundred and thirty-nine pts (65%), group PC (planned completion; median age 68; 28-86 years), had extensive descending TA (Ø>/=5 cm) or dissections requiring complete repair. Seventy-six pts (35%), group CS (close surveillance; median age: 68; 20-87 years), had less severe distal dilatation (Ø</=5 cm), and had close follow-up after ET rather than planned distal repair. RESULTS Hospital mortality in group PC pts (descending Ø: 6.2+/-1.2 cm) was 6.5% (9/139) following ET. In group CS pts (descending Ø: 4.1+/-0.7 cm), hospital mortality after ET was 5.3% (4/76); 4.7% (10/215) had strokes but survived. Eighty-six percent (112/130) of group PC pts who survived proximal repair returned for planned surgical (101) or endovascular (11) completion after a median of 56 (0-2189) days. Hospital mortality for distal repair was 7.5% (9/120); two ET stage two pts (2%) developed paraplegia. Eighty-nine percent (16/18; descending Ø: 6.9+/-1.0 cm) of group PC pts who did not undergo planned completion died a median of 5.4 (1.2-91.1) months after ET stage one. Overall cumulative survival in group PC, which includes pts dying before or without stage two, was 69% after 1, and 55% after 5 years. Survival in group CS pts was 88% at 1, and 57% at 5 years. Eight pts in group CS subsequently underwent distal repair, but 22/76 (29%) group CS pts who survived ET stage one died during follow-up despite surveillance. CONCLUSIONS The low mortality after stage one justifies liberal use of the ET technique to facilitate future open or endovascular TA repair of the distal aorta. The 5-year cumulative mortality curves, however, suggest that staged repair of extensive TA is superior to one-step repair only if stage two can be done before rupture occurs. If one-step repair is possible, it may be preferable.

How does the ascending aorta geometry change when it dissects

OBJECTIVES The purpose of this study is to delineate changes in aortic geometry and diameter due to dissection. BACKGROUND Aortic diameter is the major criterion for elective ascending aortic replacement for dilated ascending aortas to prevent aortic dissection. However, recommendations are made on the basis of clinical experience and observation of diameters of previously dissected aortas. METHODS Six tertiary centers on 2 continents reviewed their acute aortic dissection type A databases, which contained 1,821 patients. Included were all non-Marfan patients with nonbicuspid aortic valves who had undergone computed tomography angiography <2 years before and within 12 h after aortic dissection onset. Aortic geometry before and after dissection onset were compared. RESULTS Altogether, 63 patients were included (27 spontaneous and 36 retrograde dissections, median age 68 [57; 77] years; 54% were men). In all but 1 patient, maximum ascending aortic diameter was <55 mm before aortic dissection onset. The largest increase in diameter and volume induced by the dissection were observed in the ascending aorta (40.1 [36.6; 45.3] mm vs. 52.9 [46.1; 58.6] mm, +12.8 mm; p < 0.001; 124.0 [90.8; 162.5] cm(3) vs. 171.0 [147.0; 197.0] cm(3), +47 cm(3); p < 0.001). Mean aortic arch diameter increased from 39.8 (30.5; 42.6) mm to 46.4 (42.0; 51.6) mm (+6.6 mm; p < 0.001) and descending thoracic aorta diameter from 31.2 (27.0; 33.3) mm to 34.9 (30.9; 39.5) mm (+3.7 mm; p < 0.001). Changes in thoracic aorta geometry were similar for spontaneous and retrograde etiology. CONCLUSIONS Geometry of the thoracic aorta is affected by aortic dissection, leading to an increase in diameter that is most pronounced in the ascending aorta. Both spontaneous and retrograde dissection result in similar aortic geometry changes.

Flow-sensitive four-dimensional magnetic resonance imaging: flow patterns in ascending aortic aneurysms.

OBJECTIVE Pathological aortic flow patterns differ significantly from haemodynamics within the healthy aorta. Development and impact of pathological flow is largely unknown and might affect pathogenesis and the progression of thoracic aortic diseases. This study presents pathological blood-flow patterns within a series of six patients suffering from ascending aortic aneurysms investigated with high-detail flow-sensitive, four-dimensional (4D)-MRI and three-dimensional (3D) computer-aided flow-visualisation strategies. METHODS Data were acquired on a 3T magnetic resonance system (TRIO, Siemens, Erlangen, Germany) using a flow-sensitive 4D (time-resolved 3D) sequence protocol. Measurements were taken in synchrony with the cardiac cycle and under respiration control. After data pre-processing, blood-flow was visualised by means of systolic 3D streamlines and time-resolved 3D particle traces using the software EnSight (CEI, Apex, NC, USA) and homemade visualisation tools. We investigated six adult patients with ascending aortic aneurysms and one healthy individual and findings were compared to 3D-haemodynamics of the dilated ascending aorta described in current literature. RESULTS Normal blood-flow in the healthy volunteer resulted in highest velocities of up to 1 ms in the ascending and descending aorta, a right-handed helical flow pattern featuring 0.5-1.5 revolutions within the ascending aorta was present. Two atherosclerotic aneurysms presented either increased right-handed helical flow with flow acceleration along the great curvature, or multiple vortical flows in the sinuses and middle of the ascending aorta. One Marfan-associated aneurysm exhibited increased vortical flow in the dilated sinuses. One pseudo-aneurysm at the proximal anastomosis of an earlier supracoronary aortic replacement showed extensive vortex formation inside the aneurysms lumen. An aneurysm in a patient with a bicuspid aortic valve revealed one major vortex formation directly above the aortic valve. One aneurysm following congenital valvular stenosis and commissurotomy in childhood was characterised by helical diastolic backflow in the central ascending aorta and a vortex at the small curvature. CONCLUSION Patients with ascending aortic aneurysms reveal considerable differences in local flow patterns among themselves and compared to healthy individuals. Further investigations are necessary to identify flow patterns predisposing to aortic aneurysm development or adverse events in the course of aortic disease.

Selective cerebral perfusion at 28 °C - is the spinal cord safe?

OBJECTIVE To shorten cooling/rewarming associated with hypothermic neuroprotection strategies during complex aortic arch surgery, selective cerebral perfusion (SCP) at 28 degrees C has recently been advocated, although its safe limits - especially with regard to the ischaemic tolerance of the spinal cord - have not been systematically examined. METHODS Twenty juvenile Yorkshire pigs (30.3+/-2.8kg) were randomly allocated to undergo circulatory arrest and SCP at 28 degrees C for 90 min (group A; N=12) or 120 min (group B; N=8) at 50 mmHg using alpha-stat pH management. Spinal cord blood flow (SCBF) was assessed using fluorescent microspheres at baseline (prior to SCP); at 5 and 80 min during SCP, and at 1, 5 and 48 h after cardiopulmonary bypass (CPB). A modified Tarlov score was used to evaluate neurobehavioural recovery in all survivors blindly from videotapes for 5 days postoperatively. Histological ischaemic spinal cord injury was scored after sacrifice. RESULTS All pigs could be weaned from CPB and ventilation, but seven pigs (58%) in group A and five (63%) in group B developed multi-organ failure and died within 24h. SCBF diminished immediately after initiation of SCP and was absent throughout SCP in all segments below T8/9, recovering to baseline 1h after SCP at all cord levels. All survivors suffered moderate-to-severe histological lumbar spinal cord damage, more severe in group B (p< or =0.049). Three of five group A pigs recovered normal function, but two suffered paraparesis. Group B survivors had a worse neurologic outcome (p<0.0001): all suffered paraplegia (one immediate, and two on day 2, after initial recovery). CONCLUSION SCP provides insufficient SCBF below T8/9 to sustain cord viability. At 28 degrees C, the ischaemic tolerance of the cord may be exceeded enough by 90 min to impair function; by 120 min, SCP at 28 degrees C invariably results in paraplegia.

Spinal cord blood flow and ischemic injury after experimental sacrifice of thoracic and abdominal segmental arteries

OBJECTIVE Spinal cord blood flow (SCBF) after sacrifice of thoracoabdominal aortic segmental arteries (TAASA) during thoracoabdominal aortic aneurysm (TAAA) repair remains poorly understood. This study explored SCBF for 72 h after sacrifice of all TAASA. METHODS Fourteen juvenile Yorkshire pigs underwent complete serial TAASA sacrifice (T4-L5). Six control pigs underwent anesthesia and cooling to 32 degrees C with no TAASA sacrifice. In the experimental animals, spinal cord function was continuously monitored using motor evoked potentials (MEPs) until 1h after clamping the last TAASA. Fluorescent microspheres enabled segmental measurement of SCBF along the entire spinal cord before, and 5 min, 1 h, 5 h, 24 h and 72 h after complete TAASA sacrifice. A modified Tarlov score was obtained for 3 days after surgery. RESULTS All the pigs with complete TAASA sacrifice retained normal cord function (MEP) until 1h after TAASA ligation. Seven pigs (50%) with complete TAASA sacrifice recovered after 72 h; seven pigs suffered paraparesis or paraplegia. Intraoperatively, and until 1h postoperatively, SCBF was similar among the three groups along the entire cord. Postoperatively, SCBF did not decrease in any group, but significant hyperemia occurred at 5h in controls and recovery animals, but did not occur in pigs that developed paraparesis or paraplegia in the T8-L2 segments (p=0.0002) and L3-S segments (p=0.0007). At 24h, SCBF remained marginally lower from T8 caudally; at 72h, SCBF was similar among all groups along the entire cord. SCBF in the segments T8-L2 at 5h predicted functional recovery (p=0.003). CONCLUSIONS This study suggests that critical spinal cord ischemia after complete TAASA sacrifice does not occur immediately (intraoperatively), but is delayed 1-5h or longer after clamping, and represents failure to mount a hyperemic response to rewarming and awakening. The short duration of low SCBF associated with spinal cord injury suggests that hemodynamic and metabolic manipulation lasting only 24-72 h may allow routine preservation of normal cord function despite sacrifice of all TAASA secondary to surgical or endovascular repair of large TAAA.

Impact of Perfusion Strategy on Outcome After Repair for Acute Type A Aortic Dissection

BACKGROUND The impact of antegrade versus retrograde perfusion during cardiopulmonary bypass on short- and long-term outcome after repair for acute type A aortic dissection is controversial. METHODS We reviewed 401 consecutive patients (age, 59.2 ± 14 years) with acute type A aortic dissection who underwent aggressive resection of the intimal tear and aortic replacement (March 1995 through July 2011). Arterial perfusion was antegrade in 78% (n = 311), either by means of the right axillary artery (n = 297) or through direct aortic cannulation (n = 15). Retrograde perfusion through the femoral artery was used in 22% (n = 90). RESULTS Of the 401 patients with acute type A aortic dissection, 16% (n = 64) presented in critical condition and 10% (n = 39) entered the operating room under cardiopulmonary resuscitation. In 14% (n = 54) the dissection did not extend beyond the ascending aorta (DeBakey II); 82% of dissections did involve at least the aortic arch (n = 326, DeBakey I+III). Mean age was not significantly different between patients undergoing antegrade (59.4 ± 14 years) versus retrograde (59.2 ± 13 years; p = 0.489) perfusion. Operative mortality was 20% and did not differ significantly between the groups (p = 0.766); postoperative stroke occurred also with a similar prevalence (antegrade, 15% versus retrograde, 18%; p = 0.623). Patients undergoing antegrade perfusion had a better long-term survival. Survival at 10 years after discharge was 71% versus 51% (p = 0.025) in favor of antegrade perfusion. Retrograde perfusion was identified to be an independent risk factor for late mortality in multivariate analysis (hazard ratio = 2; p = 0.009). CONCLUSIONS Survival during the initial perioperative period was equivalent comparing antegrade and retrograde perfusion. Antegrade perfusion to the true lumen, however, appears to be associated with superior long-term survival after hospital discharge.

Surgical management of delayed retrograde type A aortic dissection following complete supra-aortic de-branching and stent-grafting of the transverse arch

OBJECTIVES Hybrid endovascular procedures are rapidly evolving and have recently been adopted for high-risk patients deemed unsuitable for conventional aortic arch surgery. We describe here our initial experience with this technique, including the management of 2 patients who developed a retrograde type A aortic dissection post-de-branching. METHODS Between May 2010 and October 2012, 109 patients underwent conventional aortic arch repair at our institution. A further 9 high-risk patients with complex aortic arch pathology (median logistic EuroSCORE: 26, range: 11-41) were deemed unsuitable for conventional total aortic arch replacement and therefore underwent hybrid aortic arch repair. Complete supra-aortic de-branching, followed by endovascular stent-grafting (TEVAR) of the transverse arch and descending aorta, was performed in these high-risk patients. RESULTS In-hospital mortality was zero and no patient developed paraplegia/paraparesis due to spinal cord ischaemia. However, 2 patients (22%) developed retrograde type A aortic dissection on Days 10 and 12 post-TEVAR. Both patients had a dilated ascending aorta and received a stent graft containing bare metal springs at the proximal end. Emergency ascending aortic replacement was performed during moderate-to-mild hypothermia (28-34°C) and bilateral antegrade cerebral perfusion via cannulation of the de-branching prosthesis. A Hemashield prosthetic graft was anastomosed to the proximal stent graft in an elephant trunk technique. Both patients suffered from minor non-debilitating stroke, with 1 being discharged home and 1 transferred to a neurological rehabilitation centre 2 and 3 weeks after reoperation, respectively. CONCLUSIONS Retrograde type A aortic dissection after hybrid endovascular treatment of the aortic arch represents a new-most likely under-reported-pathology that may be successfully treated with open surgical repair. The use of stent grafts with protruding proximal bare springs and the implementation of oversizing and post-deployment ballooning should be avoided in patients undergoing hybrid arch procedures, particularly if the ascending aorta is dilated.

Current Indications for Surgical Repair in Patients with Bicuspid Aortic Valve and Ascending Aortic Ectasia

Preventive surgical repair of the moderately dilated ascending aorta/aortic root in patients with bicuspid aortic valve (BAV) is controversial. Most international reference centers are currently proposing a proactive approach for BAV patients with a maximum ascending aortic/root diameter of 45 mm since the risk of dissection/rupture raises significantly with an aneurysm diameter >50 mm. Current guidelines of the European Society of Cardiology (ESC) and the joint guidelines of the American College of Cardiology (ACC)/American Heart Association (AHA) recommend elective repair in symptomatic patients with dysfunctional BAV (aortic diameter ≥45 mm). In asymptomatic patients with a well-functioning BAV, elective repair is recommended for diameters ≥50 mm, or if the aneurysm is rapidly progressing (rate of 5 mm/year), or in case of a strong family history of dissection/rupture/sudden death, or with planned pregnancy. As diameter is likely not the most reliable predictor of rupture and dissection and the majority of BAV patients may never experience an aortic catastrophe at small diameters, an overly aggressive approach almost certainly will put some patients with BAV unnecessarily at risk of operative and early mortality. This paper discusses the indications for preventive, elective repair of the aortic root, and ascending aorta in patients with a BAV and a moderately dilated—or ectatic—ascending aorta.

Double valve replacement and reconstruction of the intervalvular fibrous body in patients with active infective endocarditis

OBJECTIVES Destruction of the intervalvular fibrous body, though uncommon, occurs due to paravalvular abscess formation following active infective endocarditis. This warrants a highly complex operation involving radical surgical debridement of the intervalvular fibrous body, followed by double valve (aortic and mitral) replacement with patch reconstruction of the anterior mitral annulus, the left ventricular outflow tract and the left atrial roof. The objective of this study was to review the early and mid-term outcomes in patients undergoing this operation. METHODS A total of 25 patients underwent double valve replacement with reconstruction of the intervalvular fibrous body for extensive infective endocarditis between January 1999 and March 2012. The mean age was 64.3 ± 10.5 years. Most of the patients (60%) were in New York Heart Association Class III-IV, 12% and in cardiogenic shock. Associated comorbidities like acute renal insufficiency and cerebrovascular accidents were observed in 40 and 20% of patients, respectively. Twenty patients had previous heart valve surgeries. The logistic EuroSCORE predicted risk of mortality was 55.1 ± 22.9%. RESULTS Overall, 30-day mortality was 32%. Postoperative complications like low cardiac output, stroke and acute renal failure developed in 16, 28 and 56%, respectively. Thirty-two percent of patients required re-exploration for bleeding. Nine patients were alive at a mean follow-up of 406 days (0-8 years). The 2- and 5-year survivals were 37.0 ± 11.1 and 24.6 ± 12.5%, respectively. CONCLUSIONS Double valve replacement with reconstruction of the intervalvular fibrous body for infective endocarditis is a complex, technically challenging operation associated with high perioperative morbidity and mortality. Nevertheless, being the only option available for such complex disease, it should be performed in these patients who, otherwise, face 100% mortality.