Klaus Kallenbach

Hypothermic circulatory arrest with selective antegrade cerebral perfusion in ascending aortic and aortic arch surgery: A risk factor analysis for adverse outcome in 501 patients

OBJECTIVEnThis study was undertaken to identify preoperative and intraoperative risk factors influencing outcome after operations requiring hypothermic circulatory arrest with selective antegrade cerebral perfusion in a single center.nnnMETHODSnBetween November 1999 and March 2006, a total of 501 consecutive patients (median age 64 years, range 20-86 years, 320 male) underwent aortic arch surgery with moderate hypothermic circulatory arrest (25 degrees C +/- 2 degrees C) and additional selective antegrade cerebral perfusion (14 degrees C) at our institution for various indications (256 aneurysms, 153 acute and 23 chronic type A aortic dissections, 66 other). Of these, 181 were emergency operations. Statistical analysis was carried out to determine risk factors for 30-day mortality as well as for temporary and permanent neurologic dysfunction.nnnRESULTSnOverall mortality was 11.6%. Permanent neurologic dysfunction occurred in 48 patients (9.6%); temporary neurologic dysfunction was detected in 67 patients (13.4%). Multivariate analysis revealed age (P = .001, odds ratio 1.08), reoperation (P = .006, odds ratio 3.58), femoral arterial cannulation (P = .004, odds ratio 2.87), and cardiopulmonary bypass duration (P < .001, odds ratio 1.009) as risk factors for mortality. Permanent neurologic dysfunction was associated with preoperative renal insufficiency (P = .029, odds ratio 2.79) and operation time (P < .001, odds ratio 1.005), whereas temporary neurologic dysfunction occurred in patients with coronary artery disease (P = .04, odds ratio 2.29), emergency surgery (P = .001, odds ratio 4.09), and increasing hypothermic circulatory arrest duration (P = .01, odds ratio 1.015).nnnCONCLUSIONnModerate hypothermic circulatory arrest in combination with cold selective antegrade cerebral perfusion is an adequate tool for neuroprotection during aortic surgery. Nevertheless, the safety of this technique is limited for patients with long intraoperative durations, advanced age, and multiple comorbidities. This technique, which avoids profound core temperatures, has become an alternative to simple deep hypothermic circulatory arrest.

Hypothermic circulatory arrest during ascending and aortic arch surgery: the theoretical impact of different cerebral perfusion techniques and other methods of cerebral protection.

Operations on the thoracic aorta using hypothermic circulatory arrest are still associated with significant morbidity and mortality due to neurological complications. During the last decades, different cerebral protection techniques have been introduced into clinical practice to reduce the incidence of such complications. Furthermore clinical as well as basic researches have been performed to improve the outcome after these operations. Currently different cerebral perfusion methods are in clinical use and the superiority of one or the other method is a matter of controversial discussion. This review has been undertaken to evaluate the theoretical impact of these different methods of cerebral protection. Based on the experience of the authors the pros and cons are discussed with clinical and experimental reports from the literature.

Results of valve-sparing aortic root reconstruction in 158 consecutive patients

BACKGROUNDnThis study assesses the durability and clinical outcome of valve-sparing aortic root reconstruction using the reimplantation technique in a single center cohort.nnnMETHODSnFrom July 1993 to July 2001, 158 patients underwent replacement of the ascending aorta with native valve reimplantation. Mean age of patients was 52 +/- 17 years (9 to 84 years), 103 were men (65%). Thirty-four patients (22%) suffered from Marfans syndrome. Aortic dissection Stanford type A was present in 29 patients (19%) (22 acute, 7 chronic), and concomitant partial or total arch replacement was necessary in 57 patients (36%). One or more additional procedures were performed in 28 patients (18%). Mean follow-up was 36 +/- 25 months (0.4 to 96 months).nnnRESULTSnThirty-day mortality was 3.8% (6 patients), but only 2.2% in elective patients. Mean bypass time was 169 +/- 50 minutes (99 to 440 minutes), aortic cross-clamp time was 129 +/- 31 minutes (79 to 205 minutes). In patients undergoing arch replacement, circulatory arrest was 26 +/- 18 minutes (7 to 99 minutes). During follow-up, there were 5 (3.3%) cardiac-related late deaths. Grade of aortic insufficiency (AI) decreased from 2.3 +/- 1.1 (0 to 4) preoperatively to 0.23 +/- 0.44 (0 to 2) postoperatively (p < 0.0001). Six patients required aortic valve replacement, 4 of those due to progressive AI. Average grade of AI increased significantly to 0.42 +/- 0.61 (0 to 3) at latest evaluation (p = 0.002). Two patients experienced a transient ischemic attack within the first postoperative week. No further thromboembolic complications were noticed. All patients presented with a favorable exercise tolerance.nnnCONCLUSIONSnThe aortic valve reimplantation technique achieves excellent clinical outcome with few complications even in complex pathologies. Lack of anticoagulation and favorable durability encourage wider and earlier use of this technique.

Acellularized porcine heart valve scaffolds for heart valve tissue engineering and the risk of cross-species transmission of porcine endogenous retrovirus

OBJECTIVEnAcellularized porcine heart valve scaffolds have been successfully used for heart valve tissue engineering, creating living functioning heart valve tissue. However, there is concern about the possibility of porcine endogenous retrovirus transmission. In this study we investigated whether acellularized porcine heart valve scaffold causes cross-species transmission of porcine endogenous retrovirus in a sheep model.nnnMETHODSnAcellularized porcine pulmonary valve conduits (n = 3) and in vitro autologous repopulated porcine pulmonary valve conduits (n = 5) were implanted into sheep in the pulmonary valve position. Surgery was carried out with cardiopulmonary bypass support. The animals were killed 6 months after the operation. Blood samples were collected regularly up to 6 months after the operation and tested for porcine endogenous retrovirus by means of polymerase chain reaction and reverse transcriptase-polymerase chain reaction. In addition, explanted tissue-engineered heart valves were tested for porcine endogenous retrovirus after 6 month in vivo.nnnRESULTSnPorcine endogenous retrovirus DNA was detectable in acellularized porcine heart valve tissue. However, 6 months after implantation of in vitro and in vivo repopulated acellularized porcine heart valve scaffolds, no porcine endogenous retrovirus sequences were detectable in heart valve tissue and peripheral blood.nnnCONCLUSIONnAcellularized porcine matrix scaffolds used for creation of tissue-engineered heart valves do not transmit porcine endogenous retrovirus.

Valve-sparing aortic root reconstruction in patients with significant aortic insufficiency

BACKGROUNDnTo assess the feasibility and outcome of the valve-sparing aortic root reimplantation technique in patients with severe preoperative aortic insufficiency (AI).nnnMETHODSnWithin 8 years we have operated on 158 patients with aneurysms of the ascending aorta using the reimplantation technique. We identified 83 patients with AI grade 3 or 4 (mean 3.1 +/- 0.4) preoperatively (study group). This cohort was compared with 71 patients with AI grade 2 or less (mean 1.3 +/- 0.9; control group) with regard to mortality, operative variables, complications, need for reoperation, postoperative AI, and clinical presentation during follow-up.nnnRESULTSnPatient demographics were comparable in both groups. However, Marfans syndrome (32% versus 13%, p = 0.006) and acute type A aortic dissection (20% versus 8.4%, p = 0.059) were more frequent in the control group. In addition, bypass (177 +/- 60 minutes versus 160 +/- 36 minutes, p = 0.022) and cross clamp times (133 +/- 34 minutes versus 124 +/- 27 minutes, p = 0.049) were significantly longer in controls. Mortality was low in the study group and comparable with controls (30-day, 3.6% versus 4.2%; during follow-up, 3.8% versus 5.9%; p = not significant [NS]). Reoperation rate was almost identical in both groups (3.8% versus 4.4%, p = NS). Mean grade of AI was significantly higher in the study group early postoperatively (0.31 +/- 0.46 versus 0.18 +/- 0.42, p = 0.049) but comparable at the last visit (0.43 +/- 0.58 versus 0.42 +/- 0.62, p = NS). During follow-up neither thromboembolic complications nor bleeding events were noted in either group. Clinical performance at the last visit revealed no significant difference between the groups.nnnCONCLUSIONSnPreoperative severe aortic insufficiency does not impair the excellent outcome seen after a mean of 3 years of follow-up in patients undergoing the reimplantation technique for valve-sparing aortic root reconstruction.

Valve sparing aortic root reconstruction versus composite replacement — perioperative course and early complications

OBJECTIVEnIn patients with aneurysm of the ascending aorta, dilatation of the sinotubular junction is the major cause of aortic valve regurgitation. Valve sparing aortic root replacement in patients without valvular structural defects offers a new form of treatment. The aim of this study was the assessment of the perioperative course and early complications of this method compared to composite replacement in a large single center cohort.nnnMETHODSnFrom 1992 to 1999, valve sparing replacement of the ascending aorta (recon) has been performed in 78 patients, while 269 patients underwent replacement by a composite graft (comp). A comparison of matched pairs (n=52) with respect to age, gender, presence of Marfans syndrome, aortic dissection as well as date of surgery, was chosen. Aortic insufficiency was 2.8+/-0.7 for recon vs. 2.2+/-1.1 for comp preoperatively. Course and length of hospitalization, echocardiographic follow-up, complications, and mortality were compared at 1-year follow-up.nnnRESULTSnThere were no operative deaths. During follow-up, one patient (2%) died 5 months postoperatively (recon) vs. two patients (3.9%) in the comp group. Bypass-time (123+/-31 vs. 153+/-31 min, P<0.0001) and cross-clamp-time (82+/-22 vs. 120+/-23 min, P<0.0001) were significantly shorter in comp. Stay in ICU (1.9+/-1.6 for recon vs. 2.3+/-2.1 days for comp) and post-op hospitalization (18.3+/-5.7 vs. 21.2+/-11.1 days) were comparable. Improvement of NYHA-class was significant after both operations (recon 2.6+/-0.8 vs. 1.3+/-0.5 and for comp 2.4+/-0.6 vs. 1.5+/-0.7, both P<0.0001). One patient (1.9%) in the recon group had to be reoperated for valve failure. Thrombembolic or bleeding complications were observed in 6 patients (12%) in comp, zero in recon (P=0.027).nnnCONCLUSIONnValve sparing aortic root reconstruction is feasible with low perioperative morbidity and mortality and good early results. Major advantages of recon are significant reduction of thrombembolic and anticoagulation related complications as opposed to longer cross-clamp and bypass times as well as a valve failure in one patient. Further follow-up is needed to confirm our data in a long-term perspective.

German Registry for Acute Aortic Dissection Type A (GERAADA) - Lessons Learned from the Registry

A German registry for acute aortic dissection type A (GERAADA) was initiated by the Working Group for Aortic Surgery and Interventional Vascular Surgery of the German Society for Thoracic and Cardiovascular Surgery (GSTCVS) in July 2006. This web-based database was developed to record the data of patients who had undergone surgery for aortic dissection type A. From analyzing the data, we aim to learn how to improve surgical treatment and to identify parameters affecting patient outcome. In the beginning, 33 cardiac centers participated via online access to the registry on the GSTCVS homepage. Since then, 43 centers in Germany, Switzerland and Austria have begun entering data on the pre- and intraoperative status of their patients, postoperative complications, mid-term results and circumstances of death. We have succeeded in interpreting the initial results and trends from the registry now available to all of the participating centers, which benefit from this shared pool of analyzed data by optimizing their therapy regimes and comparing their success with that in the other centers.

Acute dissection of the ascending aorta: first results of emergency valve sparing aortic root reconstruction

OBJECTIVEnAcute dissection of the ascending aorta requires immediate surgical intervention. In this study, we report our first results with valve sparing aortic root reconstruction removing all the diseased tissues.nnnMETHODSnFrom August 1995 to December 2000, 22 patients with acute aortic dissection of the ascending aorta (Stanford type A) underwent valve sparing aortic root reconstruction. Their ages ranged from 20 to 76 years (52+/-15, 68% males). Dissection was found in the ascending aorta (3 patients) or both in the ascending aorta and aortic arch (19 patients; 86%). Course and length of hospitalization, echocardiographic and clinical follow-up, complications and mortality were analysed.nnnRESULTSnMean cardiopulmonary bypass time was 212+/-56 min (134-352 min), mean aortic cross clamp time was 157+/-24 min (114-205 min). In patients undergoing additional arch replacement (n=19), circulatory arrest was 35+/-18 min (11-75 min). After reconstruction, intraoperative echocardiography showed aortic insufficiency (AI) grade 0 in 16 patients (84%) and grade 1 in three patients (16%). Stay in intensive care unit was 2.1+/-0.7 days, and postoperative hospitalization was 21+/-14.4 days. There were three perioperative deaths (14%). Mean post-operative follow-up was 18.4+/-18 months (0.4-65.4 month). One patient died 10 months postoperatively. At follow-up, no patient suffered AI grade 2 or higher, and no reoperation for aortic valve failure was necessary. All patients presented with a favorable exercise tolerance being in New York Heart Association functional class I or II.nnnCONCLUSIONnValve sparing aortic root reconstruction in patients with type A dissection can be performed with acceptable intraoperative mortality and morbidity and excellent results during follow-up. The complete resection of the diseased aorta is particularly appealing.

German Registry for Acute Aortic Dissection Type A (GERAADA)--new software design, parameters and their definitions.

BACKGROUNDnThe working group for aortic surgery and interventional vascular surgery of the German Society for Thoracic and Cardiovascular Surgery (GSTCVS) initiated the web-based German Registry for Acute Aortic Dissection type A (GERAADA). It is the projects aim to collect standardized data from a large pool of patients with acute aortic dissections type A (AADA) to gain a deeper insight and knowledge to improve surgical therapies and perioperative management for these patients in the future.nnnMETHODSnIn addition to new medical insights, the working group has gained more experience over the last 4 years in how to collect valid and high-quality data. This experience led us to revise the database completely. In this article we describe the new version of GERAADA, providing an overview as well as defining the parameters, and explaining the new features. This overview fulfills a request by the users of GERAADA in the participating centers.nnnRESULTSnSince its inception, 50 cardiac centers in Germany, Austria and Switzerland have provided over 2000 records and the first statistical results have been published.nnnCONCLUSIONnGERAADAs new design allows it to stay abreast of changes in medicine and to focus on the essentials necessary for statistically relevant results, while keeping the work load low for the data providers at each cardiac center.

Aortic root surgery in combination with hypothermic circulatory arrest: preserve or replace the aortic valve in the context of postoperative neurological outcome? A case match comparison.

The objective of this study was to compare the results of elective composite (C) vs. David (D) operations in patients requiring additional aortic arch surgery using hypothermic circulatory arrest (HCA) and selective antegrade cerebral perfusion (SACP), with the focus on postoperative neurological outcome and quality of life (SF-36). Between November 1999 and March 2006, 333 patients underwent aortic root surgery and ascending aortic replacement with HCA and SACP at our institution. Out of these patients, 46 were matched with respect to age, gender, HCA-time and year of surgery. Two patients, one in each group, died during hospital stay (4%), with no late deaths. Follow-up was completed in 95% [64 (6-90) months]. Cardiopulmonary bypass (CPB) time (141 min vs. 168 min, P=0.007) and aortic cross-clamp time (99 min vs. 123 min, P=0.004) were significantly longer in the David-group. The incidence of temporary neurological dysfunction (TND 7%: D n=1, C n=2) was not different between groups, no permanent dysfunction could be detected. Follow-up SF-36 scores were comparable. The combination of aortic arch surgery with more time consuming valve sparing aortic root surgery does not increase the risk for adverse outcome applying comparable periods of HCA and SACP.