Ulf Herold

Endoluminal stent graft repair for acute and chronic type B aortic dissection and atherosclerotic aneurysm of the thoracic aorta: an interdisciplinary task

OBJECTIVE Endoluminal thoracic aortic stenting is a new therapeutic tool in reducing the operative trauma of the patient. However, the inherent risks of aortic stent grafting are perivascular leakage, stent dislocation, blunt rupture of the aorta, side branch occlusion and neurological sequelae. To reduce these risks, in our institution all stent implantations were performed in close collaboration with our fellow cardiologists under biplane X-ray control supported by simultaneous intravascular and transoesophageal ultrasound imaging. METHODS Between August 1999 and August 2001, endovascular stent graft repair was performed in 34 patients (27 male, seven female) with a mean age of 68.6+/-7 years (range 58-84). Indication for treatment was an acute Type B aortic dissection in six patients (18%), a symptomatic chronic Type B dissection in 12 patients (35%), a true aneurysm of the descending aorta in seven patients (21%) and an atherosclerotic contained rupture of the descending aorta in nine (26%) patients. Out of six acute type B dissections three patients (8.8%) and one patient (2.9%) out of the chronic dissection group were in severe haemorrhagic shock, ventilated and required high-dose adrenergic support. The others (30 patients, 88.3%) remained symptomatic despite maximum medical treatment. In a special case a combined surgical and endoluminal stent graft repair was performed. Individually manufactured Talent, Medtronic AVE (33), and Gore (1) stents were used. Follow-up examination was performed 1 week after implantation and repeated every 3 months (mean follow-up 8 months, range 1-24). RESULTS In all patients the aneurysm or the entry of the dissection could be excluded. The observed hospital mortality was 2.9% (one patient). No perivascular leakage, no stent dislocation, no neurological deficit or perfusion impairment was observed. All patients except four were extubated immediately after the procedure and discharged from hospital on postoperative day 2-3. The late procedure-related mortality was 5.8% (two patients) resulting in an overall mortality of 8.8% (three patients). CONCLUSION Stent graft repair is a safe and feasible treatment option for selected patients, especially in emergency situations, if the aortic lesions can be clearly identified and localized. The use of biplane X-ray control combined with simultaneous intravascular and transoesophageal ultrasound imaging in an interdisciplinary approach enables a more precise targeting of the stent landing zone, resulting in low morbidity and mortality rates.

Prognostic Significance of Multiple Previous Percutaneous Coronary Interventions in Patients Undergoing Elective Coronary Artery Bypass Surgery

Background— A possible relationship between increased perioperative risk during coronary artery bypass grafting (CABG) and previous percutaneous coronary intervention (PCI) is debatable. We sought to determine the impact of previous PCI on patient outcome after elective CABG. Methods and Results— Between January 2000 and January 2005, 2626 consecutive patients undergoing first-time isolated elective CABG as the primary revascularization procedure (group 1) were evaluated for in-hospital mortality and major adverse cardiac events (MACEs) and were compared with 360 patients after single PCI (group 2) and with 289 patients after multiple PCI sessions (group 3) before elective CABG. Unadjusted univariate and risk-adjusted multivariate logistic-regression analysis revealed previous multiple PCIs to be strongly associated with in-hospital mortality (odds ratio [OR], 2.24; 95% confidence interval [CI], 1.52 to 3.21; P<0.001) and MACEs (OR, 2.28; 95% CI, 1.38 to 3.59; P<0.001). To control for selection bias, a computed propensity-score matching based on 13 patient characteristics and preoperative risk factors was performed separately comparing group 1 versus 2 and group 1 versus 3. After propensity matching, conditional logistic-regression analysis confirmed previous multiple PCIs to be strongly associated with in-hospital mortality (OR, 3.01; 95% CI, 1.51 to 5.98; P<0.0017) and MACEs (OR, 2.31; 95% CI, 1.45 to 3.67; P<0.0004). Conclusions— In patients with a history of multiple PCI sessions, perioperative risk for in-hospital mortality and MACEs during subsequent elective CABG is increased.

Coronary artery bypass surgery and acute kidney injury—impact of the off-pump technique

BACKGROUND Acute kidney injury (AKI) is a serious and frequent complication after coronary artery bypass grafting (CABG). Cardiopulmonary bypass (CPB) was identified as a major AKI risk factor after CABG. Our aim was to assess the impact of the off-pump coronary artery bypass (OPCAB) compared to the on-pump coronary artery bypass (ONCAB) technique on the rate and severity of AKI, while taking other risk factors for AKI into account. METHODS An observational study of 201 consecutive adult patients was conducted; 100 were operated by the OPCAB and 101 by the ONCAB technique. All patients in each group were operated by a single, experienced surgeon. Fifteen pre-, intra- and postoperative variables that were repeatedly identified in previous studies as independent AKI risk factors were included in this analysis. AKI was defined as an increase of serum creatinine >/=50% or >/=0.3 mg/dL within 48 h and AKI severity was classified, according to current AKIN definitions. RESULTS Significantly fewer OPCAB patients developed AKI compared to ONCAB (14.0 versus 27.7%; P = 0.03). OPCAB was associated with milder stages of AKI, whereas ONCAB patients had more severe AKI. Congestive heart failure and chronic kidney disease were independent risk factors for AKI. The OPCAB technique for CABG was identified as the only independent factor associated with lower incidence of AKI. CONCLUSIONS Using current AKI definitions and classifications, the OPCAB technique for CABG, which avoids CPB; was associated with a significantly lower rate and less severe AKI compared to ONCAB. The OPCAB technique was identified as the only modifiable and potentially protective factor against postoperative AKI.

Development of an integrated stent graft-dacron prosthesis for intended one-stage repair in complex thoracic aortic disease.

Complex thoracic aortic disease involving the ascending aorta, the aortic arch and the descending aorta still represents a challenge for the cardiothoracic surgeon. The classic approach for this pathology consists of a two-stage strategy, summing up to a mortality up to 40%, with a 5% mortality for the waiting period between both surgical stages [1–3]. One-stage repair can be performed, if required, via a clamshell thoracotomy, but is associated with major surgical trauma and perioperative morbidity as pulmonary or renal dysfunction, indicating that elderly patients probably are poor candidates for this strategy [4]. With the introduction of endovascular stenting in combination with classic aortic arch surgery an attractive treatment alternative has emerged for facilitated repair of complex aneurysmal disease in the thoracic aorta [5, 6]. Modifying this new technique using self-expanding descending aortic stent grafts and the classic ascending and aortic arch replacement techniques seems to be the logical consequence for intended one-stage repair, which was started by our group 06/2001 [7, 8]. Standard thoracic aortic stent graft devices (e.g., Medtronic Talent©, Minneapolis, MN, USA) are designed for retrograde aortic delivery, which demonstrate shortcomings for the antegrade use: their stiffness limits steerability, causing problems to pass the angle between the distal aortic arch and proximal descending aorta, resulting in significant friction to the inner aortic wall. This is worsened by the stiff outer plastic sheath which frequently shows kinking when curved > 45°. The most rigid zone is identified to be at the proximal border between stent graft and tip of the introducer and at the distal site between stent graft and the wire-reinforced inner pusher, limiting continuous and precise stent graft opening. At that point the already opened distal bare springs only allow for minor correction in proximal direction in case of displacement. A second significant problem is caused by the longitudinal wire (connecting bar), which is positioned along the outer curvature of the stent. This force provokes the stent to straighten up resulting in a significant protrusion of the proximal bare springs into the aortic wall. To overcome those shortcomings, a new integrated stent graft-Dacron prosthesis for antegrade delivery through the open aortic arch into the descending aorta in an “elephant trunk”-like manner was created. This “Essen I prosthesis” (E-vita open; Jotec®, Hechingen, Germany [Figure 1]) consists of a polyester fabric with an extremely flexible Nitinol wire skeleton, fixed on the outer aspect of the fabric with polypropylene sutures. To increase flexibility, a longitudinal wire is abandoned, and no open bar ends or reinforced circular springs are incorporated distally or proximally. At the proximal end, a woven crimped vascular Dacron prosthesis of 7 cm length is incorporated continuously to the stent graft prosthesis, allowing for direct replacement of the aortic arch without an additional anastomosis like in classic elephant trunk operations, by simply pulling back the invaginated Dacron prosthesis at its sewn suture sling into the arch position. Stent graft re1 Department of Thoracic and Cardiovascular Surgery, West German Heart Center Essen, University Hospital Essen, Germany, 2 Department of Cardiology, West German Heart Center Essen, University Hospital Essen, Germany.

Penetrating atherosclerotic ulcer of the aorta: treatment by endovascular stent-graft placement.

Purpose of the review To summarize the current clinical experience with endovascular stent-graft repair in patients presenting with penetrating atherosclerotic ulcer of the descending thoracic aorta. Recent findings Penetrating atherosclerotic ulcer is increasingly acknowledged as a pathologic variant of classic false lumen aortic dissection with a high incidence of bleeding complications and rupture in up to 40% of patients. So far, no generally accepted therapeutic regimen has been established, as the natural history of penetrating atherosclerotic ulcer is not yet fully understood. Recently, however, penetrating atherosclerotic ulcer is increasingly considered to be treated more aggressively (preferentially surgically). Given the high morbidity and mortality of aortic surgery, endovascular stent-graft repair may be an attractive, less invasive alternative in selected patients with penetrating atherosclerotic ulcer. Sealing of a penetrating ulcer by the stent-graft reduces wall stress and thus provides stabilization of the diseased aortic segment. Summary To date, there is limited experience with endovascular repair in penetrating atherosclerotic ulcer, suggesting that endovascular stent-graft repair is safe and effective. Long-term results are, however, required to fully establish the efficacy of endovascular repair in penetrating atherosclerotic ulcer.

Endovascular stent-graft placement for complications of acute type B aortic dissection.

Purpose of review To review the concepts and current clinical results of endovascular stent-graft placement for acute complicated type B aortic dissection. Recent findings The optimal treatment for patients with dissections confined to the descending aorta (Stanford type B-AD) remains a matter of debate. Usually, antihypertensive medical therapy with strict blood pressure lowering below 135/80 mm Hg represents the first choice for patients with uncomplicated type B-AD. Patients with acute complicated type B-AD remain a major therapeutic challenge because surgery of the descending aorta is still associated with high morbidity and mortality. In 1999, endovascular stent-graft placement was introduced as a novel, less invasive treatment option for patients with type B aortic dissection. Current indications include acute (contained) aortic rupture, symptomatic ischemic branch vessel involvement, early aortic expansion, or unrelenting pain. So far, few studies on stent-graft placement in patients with acute complicated aortic dissection have been published reporting an early mortality between 0 and ∼20%. Summary To date, there is limited experience with endovascular stent-graft placement for acute complicated type B aortic dissection demonstrating its feasibility and life-saving potential. The endovascular approach can avoid the major trauma of open surgery and should help to get patients out of the acute life-threatening phase of the disease; however, long-term results are needed to assess the durability of this treatment.

Endovascular stent-graft repair for penetrating atherosclerotic ulcer of the descending aorta.

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Critical illness polyneuropathy: a new iatrogenically induced syndrome after cardiac surgery?

OBJECTIVE Critical illness polyneuropathy (CIP) is a newly described severe complication after open heart surgery leading to tetraplegia for weeks to months. The purpose of the study was to gather further information on critical illness polyneuropathy developing in patients after cardiac surgery and to evaluate the hypothetical risk factors possibly related to the onset of this neurological disorder. METHODS From July 1994 to October 1995, 7 out of 1511 patients undergoing open heart surgery developed critical illness polyneuropathy, which was diagnosed on the basis of electromyographic and nerve conduction features. The only common clinical finding was an intensive care unit (ICU) stay beyond seven days, therefore a similar group of 37 patients staying longer than seven days in the intensive care unit during the same period of time was evaluated and retrospectively compared to the 7 patients developing critical illness polyneuropathy. Univariate analysis of several traits was performed to evaluate possible risk factors. RESULTS 4 Out of 7 patients in the CIP group died, all due to multiple organ failure, in contrast to 3/37 patients in the control group, again due to multiple organ failure. Patients developing CIP were staying significantly longer in the ICU (62+/-3 versus 14+/-8 days, P < 0.01) and had a significantly longer time on ventilator support (50+/-28 versus 7+/-13 days, P < 0.01) The incidence of sepsis was significantly higher in the CIP group than in the control group (85.7 versus 10.8%, P < 0.01). Compared to the control group the proportion of patients receiving corticosteroids (100 versus 10.8%, P < 0.01) and increased dosages of epinephrine and norepinephrine was higher in the CIP group (85.7 versus 35.1%, P < 0.05). Furthermore, the proportion of patients requiring chronic venovenous hemodiafiltration was significantly elevated in the CIP group (85.7 versus 5.4%, P < 0.01). CONCLUSIONS CIP, despite its benign nature due to its spontaneous remission in patients who survive, is a disturbing complication following cardiac surgery which is associated with high mortality, a prolonged stay in the ICU, as well as an extended time on ventilator support. Interventions like chronic hemodiafiltration, the application of corticosteroids and the administration of high doses of catecholamines are more frequent in patients with CIP. Whether this indicates a causal relationship remains to be elucidated.

Interruption of bronchial circulation leads to a severe decrease in peribronchial oxygen tension in standard lung transplantation technique

OBJECTIVE In clinical practice lung transplantation is the only procedure where the transplanted organ is left without its own arterial perfusion. With the interruption of the bronchial arteries the nutritive support is dependent on collateral flow by the pulmonary artery and the oxygen tension of desaturated central venous blood, representing an abnormal physiology. METHODS To analyze this problem systematically, we used a standard single left lung transplantation model in the pig (n = 12). In accordance with the clinical standard, lung preservation was performed with modified Euro-Collins solution with addition of prostacycline. The duration of ischemia was set to 4 h. Before and after single left lung transplantation tissue oxygen tension in the peribronchial tissue was measured with Licox tissue pO2 microprobes. For validation, the myocardial tissue oxygen tension was recorded simultaneously. The hemodynamic assessment included continuous flow measurement of the left and right pulmonary artery using Transsonic ultrasound flow probes. After transplantation the animals were observed for 4 h. For hypothetic augmentation of collateral blood flow to the peribronchial tissue we administered Nitric oxide (10 ppm) to the ventilation in six pigs (group B). Six pigs (group A) served as a control without the addition of nitric oxide (NO). All pigs were ventilated with a FiO2 of 0.5 resulting in paO2 values between 160 and 200 mmHg. RESULTS In both groups single lung transplantation led to a significant decrease in peribronchial tissue oxygen tension throughout the observation period. Pre-Tx values of peribronchial tissue oxygen tension (38.31 +/- 6.56 mmHg) decreased to 9.72 +/- 2.55 mmHg in group A and 10.3 +/- 3.61 mmHg in group B after 4 h, which could not be altered by a FiO2 of 1.0 (P < 0.0001). The addition of NO in group B led to a significantly augmented flow in the left pulmonary artery (0.63 +/- 0.31 l/min in group B vs. 0.46 +/- 0.26 l/min group A, P < 0.001) representing 67 vs. 49% of the pre-Tx flow in groups B and A, respectively, but the peribronchial tissue oxygen tension was not influenced (P > 0.05). In both groups A and B, the central venous pO2 did not differ in the postoperative period (41.83 +/- 3.27 mmHg group A vs. 43.26 +/- 2.98 mmHg group B) and was kept in a comparable range to the pretransplantation values (45.23 +/- 3.41 mmHg pre-Tx). CONCLUSIONS The persistence of a very low peribronchial tissue oxygen tension in the early phase after lung transplantation cannot be influenced by improved pulmonary artery flow and solely relates to the central venous pO2, which cannot be augmented by the addition of NO. This mechanism might be a trigger for anastomotic healing problems, infectious complications and later development of obliterative bronchiolitis (OB).

Thromboelastometry Based Early Goal-Directed Coagulation Management Reduces Blood Transfusion Requirements, Adverse Events, and Costs in Acute Type A Aortic Dissection: A Pilot Study

Background: In aortic surgery bleeding complications can be fatal. Therefore, rotational thromboelastometry(ROTEMTM)based coagulation management was introduced. Methods: After 5 cases of acute type A aortic dissection and aortic arch replacement had been treated based on ROTEM findings (ROTEM group; RG), 5 cases without ROTEM were matched as control group (CG). CG treatment was based on conventional tests and clinical findings. Blood component and coagulation factor requirements, ventilation time, duration of stay at intensive care unit (ICU), hospitalization, and thrombotic or bleeding incidents as well as transfusion-associated costs were compared. Results: Administration of blood products and coagulation factor concentrates, ventilation time, ICU length of stay, and hospitalization tended to be lower in RG. Postoperative plasma transfusion (p = 0.038), recognized incidents (p = 0.048), and resulting costs on coagulation treatment (p = 0.049) were significantly reduced. Conclusion: Our data suggest that ROTEM-based coagulation management can reduce transfusion requirements and corresponding costs in patients with aortic arch replacement. These data has to be confirmed by prospective randomized trials.