Extrakorporale Herz- und Lungenersatzverfahren

Die Verwendung eines extrakorporalen Unterstützungsystems stellt bei kardialem und/oder pulmonalem Versagen eine etablierte Therapieoption dar. Auch wenn die wissenschaftliche Evidenz quantitativ noch nicht ausreichend gesichert ist, gibt es zunehmend Hinweise aus einzelnen Studien [z. B. Conventional Ventilation or ECMO for Severe Adult Respiratory Failure (CESAR) Trial], dass die „extracorporeal membrane oxygenation“ (ECMO) als pumpenbetriebenes venovenöses Verfahren beim schweren Lungenversagen eine lebensrettende Maßnahme ist. Initial als „rescue option“ beim kardialen Versagen nach Kardiotomie etabliert, erfährt der „extracorporeal life support“ (ECLS) zunehmende Verbreitung als pumpenbetriebenes venoarterielles Herz-Kreislauf-Unterstützungsystem im kardiogenen Schock bei Myokardinfarkt, als „Bridging“-Maßnahme zur Transplantation und im Rahmen einer erweiterten Reanimation. Der „pumpless extracorporeal lung assist“ (pECLA) als pumpenloses arteriovenöses Verfahren ist technisch einfacher zu handhaben, garantiert jedoch nur eine suffiziente Decarboxylierung ohne ausreichende Oxygenierung. Daher wird dieses Verfahren insbesondere im Rahmen eines primär hyperkapnischen Lungenversagens mit respiratorischer Acidose angewendet, um eine lungenprotektive Beatmung zu ermöglichen. Enorme technische Enwticklungen und v. a. die extreme Miniaturisierung der extrakorporalen Unterstützungsysteme dürfen jedoch nicht darüber hinwegtäuschen, dass es sich um eine invasive Therapie mit einer hohen Inzidenz von schwerwiegenden Komplikationen handelt. Vor diesem Hintergrund müssen die weite Verbreitung dieser Technologie kritisch hinterfragt und vielmehr die Konzentrierung auf Zentren mit hoher Expertise gefordert werden.

Randomized comparison of synchronous CABG and carotid endarterectomy vs. isolated CABG in patients with asymptomatic carotid stenosis: the CABACS trial

RATIONALE

High-grade carotid artery stenosis is present in 6-8% of patients undergoing coronary artery bypass graft surgery. Many cardiovascular surgeons advocate staged or synchronous carotid endarterectomy to reduce the high perioperative and long-term risk of stroke associated with multivessel disease. However, no randomized trial has assessed whether a combined synchronous or staged carotid endarterectomy confers any benefit compared with isolated coronary artery bypass grafting in these patients.

AIMS

The objective of this study is to compare the safety and efficacy of isolated coronary artery bypass grafting vs. synchronous coronary artery bypass grafting and carotid endarterectomy in patients with asymptomatic high-grade carotid artery stenosis.

DESIGN

Coronary Artery Bypass graft surgery in patients with Asymptomatic Carotid Stenosis (CABACS) is a randomized, controlled, open, multicenter, group sequential trial with two parallel arms and outcome adjudication by blinded observers. Patients with asymptomatic high-grade carotid stenosis scheduled for elective coronary artery bypass grafting will be assigned to either isolated coronary artery bypass grafting or synchronous coronary artery bypass grafting and carotid endarterectomy by 1 : 1 block-stratified randomization with three different stratification factors (age, gender, modified Rankin scale).

STUDY

The trial started in December 2010 aiming at recruiting 1160 patients in 25 to 30 German cardiovascular centers. The composite primary efficacy end point is the number of strokes and deaths from any cause (whatever occurs first) within 30 days after operation. A 4·5% absolute difference (4% compared to 8·5%) in the 30-day rate of the above end points can be detected with >80% power.

OUTCOMES

The results of this trial are expected to provide a basis for defining an evidence-based standard and will have a wide impact on managing this disease.

Myocardial infarction: an important factor for surgical decision making?

BACKGROUND

Recent myocardial infarction has been identified as a risk factor and is currently used as a strong predictor in different scores. The aim of our study was to determine whether the impact of myocardial infarction, especially acute myocardial infarction, is still strong enough to justify a restrictive indication for isolated CABG procedure in patients with significant coronary artery disease.

METHODS

10 272 patients underwent isolated CABG at a single institution. A 10-year follow-up was performed with a completeness of 97.2 %.

RESULTS

6 107 (59.5 %) of the patients had a history of myocardial infarction. A stratified Kaplan-Meier analysis demonstrates a significantly worse survival for patients with myocardial infarction (chi-square value: 36.7, P < 0.0001). At a further differentiation for no myocardial infarction (n = 4 165), myocardial infarction > 90 days (n = 4 578), myocardial infarction up to 90 days (recent myocardial infarction) (n = 1 266) and ongoing acute myocardial infarction up to 15 days (n = 263), indicated a higher mortality for the more recent infarction in the univariate analysis. However, if patients with acute myocardial infarction in the past 6 years were analyzed separately, their risk remained at the same level as patients with non-acute myocardial infarction over the total observation period. Furthermore, propensity score matching revealed no statistical significant difference in the outcome of the patients.

CONCLUSIONS

Structural myocardial damage represents a risk factor for survival after isolated CABG in univariate analysis. More appropriate statistical methods indicate a time-dependent loss of statistically relevant differences between patients with or without myocardial infarction prior to CABG. This is also true for "recent" myocardial infarction which is still part of current scores.

Thorakale Aorten-Stentgraftimplantation

BACKGROUND AND OBJECTIVE

Endovascular stent-graft placement is emerging as a novel therapeutic option in patients with disease of the descending thoracic aorta. Quality standards for performing stent-graft procedures as well as for pre- and postoperative patient management are lacking, so far. It was the aim of this present survey to assess the current therapeutic standard of thoracic aortic stent-graft placement in Germany.

METHODS

In a nationwide survey, a total of 206 vascular surgical, radiologic, cardiologic, and cardiothoracic surgical departments were contacted. Data concerning preoperative procedure planning, logistics, practical/technical issues of stent-graft placement, and postoperative patient management were evaluated using a standardized questionnaire comprising 29 items. Data analysis was performed using univariate analysis.

RESULTS

184 (89.3 %) of the 206 departments participated in the survey. Of these, 71 centers reported intending to perform or having performed thoracic aortic stent-graft placement. The survey overall represents 2267 endovascular stent-graft procedures performed in Germany between 1997/98 and 2003. On average, 7.4 stent-graft procedures/year were performed by each center, with half the centers performing fewer than 5 procedures/year. Thoracic aortic aneurysms was the main indication for endovascular stent-graft placement, followed by aortic dissection. There were significant differences between the different medical specialties which perform stent-graft procedures with respect to indications, choice of preoperative and intraoperative imaging methods, and technical equipment. There was strong agreement between the different centers concerning the necessity of a life-long follow-up after stent-graft placement, with computed tomography being the preferred imaging technique (90 % of centers).

CONCLUSION

The present survey documents an increasing use of endovascular stent-graft placement in patients with disease of the descending thoracic aorta. There were differences regarding the technical execution of this procedures between specialties with respect to indication, procedure planning, and practical-technical aspects of stent-graft placement.

Heart transplantation and consecutive mitral valve replacement

A 48-year-old man was diagnosed with progressive mitral insufficiency due to fibrosis of papillary muscles and chordae tendineae, necessitating mitral valve replacement (MVR) 8 months after cardiac transplantation. Donor echocardiography and inspection of the heart at procurement were inconspicuous. The patient is alive, free from valve-related complications and functionally improved six years after MVR. The limited yet successful experiences with left-sided valve repair or replacement in the transplanted heart are reviewed.

The endogenous pathway is a major route for deep sternal wound infection

OBJECTIVE

Deep wound infections pose an increasing problem in cardiac surgery patients. Prospective infection monitoring is thus a means of identifying possible risk factors.

METHODS

Within a period of 5 months, a total of 376 adult patients, 260 men and 116 women, with a mean age of 62.6 years (range 18-88), underwent coronary bypass grafting (n=281) or other cardiac surgery procedures (n=95). Nasal cultures were taken preoperatively from every patient, as well as cultures of the wound during surgery and when dressings were changed thereafter. In addition, nasal cultures were taken from all the medical and nursing staff. To differentiate endogenous and exogenous infection pathways, DNA fingerprint analysis was performed.

RESULTS

A total of 38 patients (10.1%) developed a wound infection, in 14 patients this happened to be a deep wound infection, in 24 patients a superficial one. Five sternal wound infections were associated with mediastinitis (1.3%). The occurrence of a wound infection overall resulted in prolonged hospitalization (29.4+/-24 vs. 11.9+/-6.9 days, P=0.001), but not in increased hospital mortality (4.4% vs. 3.9%). Obesity, diabetes mellitus and nasal carriage of Staphylococcus aureus proved to be independent risk factors with an odds ratio of 2.07, 2.26 and 2.28, respectively. In all but one of the sternal colonizations with S. aureus, DNA fingerprint analysis demonstrated an identical pattern of S. aureus from the patient's nose and sternum, indicating an endogenous infection pathway.

CONCLUSIONS

The determination of the endogenous pathway for severe wound infection makes prevention possible by means of preoperative local S. aureus eradication.

Operation for infective endocarditis: results after implantation of mechanical valves

BACKGROUND

Operation for acute endocarditis during the active phase violates a basic surgical rule not to implant a foreign body into an infective process, resulting in a high operative mortality and the risk of early recurrent endocarditis. Several investigators analyzing risk factors for perioperative mortality and morbidity presented strategies for more favorable outcomes, but most studies suffer from the drawback of heterogeneous populations observed over a long period of time.

METHODS

We present a prospective study on 138 patients operated on from March 1988 to March 1996. Patients were only included if the activity of the infection was proved by positive culture of the valve leaflets or by histologic staining. During the observation period, indication for operation, surgical approach, and postoperative antibiotic therapy were standardized as much as possible. After radical debridement of all parts of infected tissue, valve replacement was carried out with mechanical prostheses.

RESULTS

The early mortality was 11.5% overall. High New York Heart Association functional classification, advanced age, and staphylococcal disease were significant risk factors for early mortality. The site of infection, multiple valve involvement, and prosthetic valve endocarditis did not affect the outcome. Early recurrent endocarditis was recorded in only 3 patients of the entire series.

CONCLUSIONS

In case of acute infective endocarditis, valve replacement with mechanical prostheses is a safe procedure, if radical operation and aggressive postoperative antibiotic therapy are performed. For further improvements of the results, earlier operation is advisable in patients with rapidly progressive cardiac deterioration and in most cases of staphylococcal endocarditis.

[Upper inflow congestion as initial manifestation of idiopathic mediastinal fibrosis]

In about 90% of superior vena caval obstructions the cause is a neoplasm, generally a carcinoma of the right upper lobe. Fewer than 5 percent are due to inflammatory disease of the mediastinum. A case of idiopathic, fibrosing mediastinitis with occlusion of the superior vena cava is described. The clinical symptoms, radiographic finding, diagnostic and therapeutic aspects are discussed.

Endoventricular patch plasty improves results of LV aneurysmectomy

From May 1985 to December 1991 52 patients were operated upon for postischemic left ventricular aneurysm (LV-A). Between May 1985 and July 1989 25 patients (group I) with a mean age of 59 (46-72) years underwent conventional aneurysmectomy with direct closure of the left ventricle (LV) and a mean of 1.9 (0-3) additional bypass grafts (54% triple-vessel disease). The hospital mortality was 8% (2/25) and the late mortality during a median follow-up time of 34 months was 28% (7/25) with a 4-year survival of 66%. Improvement in the quality of life (NYHA from 2.6 to 2.1, P = 0.078) and global left ventricular ejection fraction (EF) (from 35 to 38%) proved to be unsatisfactory in conjunction with the high late mortality rate. Between August 1989 and December 1991 a prospective series of 27 consecutive patients (group II) with a mean age of 61 (45-71) years underwent endoventricular patch plasty guided by two-dimensional transthoracic echocardiography (TTE) before and after surgery. The patch size and position were calculated preoperatively by measuring the distances from the mitral annulus to the infarct area which were reproduced during surgery with a simple ruler. A mean of 2.1 (0-4) bypass grafts were added with 62% of the patients having triple-vessel disease and 19% left main stenosis (P = 0.05, group I versus II). All patients have survived to date. One patient had to be excluded, giving a median follow-up time of 14 months for 26 patients. At the 6 months' control, the mean NYHA class was improved from 2.7 to 1.6, (P = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Routine extracorporeal circulation with a centrifugal or roller pump

In a randomized, prospective clinical trial, 50 patients undergoing elective coronary artery bypass grafting (CABG) were divided into two groups of 25 each. Group I had a centrifugal pump (CP, Biomedicus) and Group II a roller pump (RP, Stöckert) as the arterial line. Neither group differed significantly, and variables during surgery were kept to a minimum. The parameters studied included the cellular blood elements and their components, such as PMN-elastase (PMN-E), plasma hemoglobin (pHb), beta-thromboglobulin (beta-TG), and D-dimer (D-D) and thrombin-antithrombin III complex (TAT) as indicators for activated coagulation. Blood and urine samples were taken at induction of anesthesia, every 15 minutes throughout extracorporeal circulation (ECC), at arrival in the ICU, and 1, 3, 6, 12, and 24 hours thereafter. No difference between the groups was found in bypass time, ECC flow or volume, or fluid balance. Significant differences in favor of Group I were found in pHb (p less than 0.05), beta-TG (p less than 0.01), D-D (p less than 0.05), and platelet counts (p less than 0.05). These differences were clearly ECC time dependent, became significant after 90 minutes of bypass, but disappeared within hours after surgery. No difference in patient outcome, ICU time, or need for volume substitution was seen. It is concluded that the RP can be safely used for routine ECC, but should be supplied with a CP in complex and prolonged cardiosurgical procedures to avoid severe postperfusion syndrome.

Diagnosis of perioperative myocardial necrosis following coronary artery surgery--a reappraisal of isoenzyme analysis

Although the routine determination of CK-MB activity is widely used after coronary artery bypass grafting (CABG), the diagnosis of a perioperative myocardial necrosis remains arbitrary. The intention of the present study was to develop discriminative enzymatic parameters of CK-MB activity in a collective of 710 patients following CABG. Patients were grouped according to their postoperative electrocardiogram (ECG). For each patient, the time activity curve of CK-MB was determined. The total amount of CK-MB was calculated by integrating the area beneath the CK-MB activity curve. Patients presenting with an unchanged postoperative ECG (group I) or a new bundle branch block with uncompromised haemodynamics (group IIa) had an uniform and low profile of CK-MB activity. Serial CK-MB activities as well as the integrated CK-MB area of these two collectives were significantly different (P less than 0.001) from values determined for patients with bundle branch block and low cardiac output (group II b) or patients with new Q waves (group III). After 24h, the 90th percentile of serial CK-MB activities of group I had declined to 18 U/l and was clearly exceeded by 90% of all patients that belonged to either group IIb or III. The 90th percentile of CK-MB areas for group I showed a value of 801 U/l x h. CK-MB areas above 801 U/l x h were seen in about 50% of all patients of group IIa.(ABSTRACT TRUNCATED AT 250 WORDS)

Emergency surgical revascularization following coronary angioplasty: evaluation of operative results by isoenzyme analysis and electrocardiography

Seventeen patients underwent emergency coronary artery bypass grafting due to balloon catheter induced occlusion or dissection of a major coronary artery. Patients were revascularized within a maximum of 210 min from the onset of ischaemia and received an average of 1.6 distal anastomoses. A perioperative transmural or non-transmural myocardial infarction as diagnosed by CK-MB activity and electrocardiographic patterns occurred in 7 patients (41.2%). One early death resulted in an overall perioperative mortality of 5.9%. Successful preservation of myocardium was demonstrated in 10 patients by a rapid decline of CK-MB activity, no perioperative electrocardiographic changes and no requirement for inotropic support. The incidence of a perioperative myocardial infarction was independent of the anginal status before coronary angioplasty or the angiographic evidence of a complete occlusion versus a dissection. Major ischaemic myocardial complications associated with coronary angioplasty are rare but frequently catastrophic events. Fast surgical intervention is mandatory to prevent myocardial infarction or to limit the extent of injury. The operative outcome can be evaluated by careful analysis of time release curves and cumulative parameters of CK-MB activity.

Influence of incremental preoperative risk factors on the perioperative outcome of patients undergoing emergency versus urgent coronary artery bypass grafting

A retrospective analysis of 127 patients with impending myocardial infarction undergoing coronary artery bypass grafting was performed to evaluate incremental risk factors associated with perioperative mortality and morbidity. Fifty-four patients (group 1) were operated upon as emergencies within 24 h and 73 patients underwent urgent coronary revascularization within a mean of 3.4 days (group II) after admission. The incidence of non-transmural myocardial infarctions (NTMI), haemodynamic parameters, the number of diseased vessels and the incidence of a preceding percutaneous coronary dilatation (PTCA) were not statistically different between the groups. The overall perioperative mortality was 8.7% (16.7% group I, 2.7% group II). Major non-fatal complications were frequent in the surviving collective including low cardiac output in 14 patients (12.1%) and transmural or subendocardial perioperative infarction in 12 patients (10.3%). Perioperative mortality was associated with reduced left ventricular myocardial function (P less than 0.001), operation within 24 hr after onset of anginal symptoms (P less than 0.001) or subendocardial infarction (P less than 0.025) in the 4 weeks before operation. Perioperative mortality was independent of the degree of coronary stenosis, number of distal anastomoses or performance of a coronary endarterectomy. Of the patients, 90.5% (87.5% of group I and 92.3% of group II) included in a mean follow-up of 16.8 months (range 5-27 months) were graded into Canadian Heart Functional Class I. Successful coronary surgery for acute myocardial ischaemia results in excellent late functional recovery. The major risk factors for fatal perioperative outcome are reduced left ventricular function and the necessity of every early surgical intervention.