Durch die Einführung der minimalinvasiven Koronarchirurgie ist das methodische Spektrum zur Behandlung der koronaren Herzerkrankung erneut differenzierter geworden. Die Möglichkeiten des minimalen Zugangs durch Teilsternotomie oder durch interkostale anteriore Minithorakotomie können mit videoskopischen Methoden und mit sog. Port-access-Verfahren kombiniert werden. Neben der normalen atrio-aortalen Kanülierung für den Anschluß der Herz-Lungen-Maschine sind jugular- und femoro-femorale Anschlüsse an die Herz-Lungen-Maschine möglich. Sogar die intravasale endoluminale Ballonokklusion der Aorta ascendens und die Applikation von kardioplegischer Lösung über den Okklusionskatheter in den Aortenbulbus können in die Überlegung einbezogen werden.

The introduction of minimally invasive coronary artery bypass surgery has expanded the technical armementarium for operative treatment of coronary artery disease. Minimal access surgery using partial sternotomy or anterior intercostal minimal thoracotomy can be combined with video-scopic techniques or port-access-methods. Either atrio-aortal cannulation, femoro-femoral or jugular-femoral connections to the pump are possible for extracorporal circulation (ECC). Even endoluminar occlusion of the aorta and application of cardioplegia into the aortic root can be considered and applied, Extracorporal circulation has developed into a safe standardized method. As far as pathophysiology is concerned, the decision to use ECC or not is of much more importance than the grade of invasiveness. Fundamentally we therefore need to distinguish between minimally invasive methods with and without ECC. Video-assisted coronary surgery in hearts under hypothermia and fibrillation with ECC is also recommended occasionally. Minimally invasive coronary artery procedures on beating hearts without ECC have to be done in a stabilized and bloodless operative field to allow the construction of high standard anastomoses between bypass grafts and coronary arteries. In practice, silicon occluders, epicardial and myocardial suture occlusion and fixation, mechanical stabilization devices, and pharmacologic induction of bradycardia are used. In principle a skilled surgeon should be familiar with all these methods to select the most suitable solution for the special clinical problem. A final judgement about each method is not possible up to now. High patient numbers have to be recruited in the groups and subgroups due to low mortality (1%) and morbidity (5%), otherwise statistical significance of the results cannot be gained.

Mediastinal infection is a feared complication observed after 0.4%-5% of cardiac operations. Even today the mortality remains as high as 20%-40%. We discuss the aetiology, mechanisms, prevention, diagnosis, and medical management. The staging system for mediastinal wound infections developed at a joint conference of German cardiac surgical centres is presented. The use of parenteral polyvalent immunoglobulins is also discussed.

The introduction of minimally invasive coronary artery bypass surgery has expanded the technical armementarium for operative treatment of coronary artery disease. Minimal access surgery using partial sternotomy or anterior intercostal minimal thoracotomy can be combined with videoscopic techniques or port-access-methods. Either atrio-aortal cannulation, femoro-femoral or jugular-femoral connections to the pump are possible for extracorporal circulation (ECC). Even endoluminar occlusion of the aorta and application of cardioplegia into the aortic root can be considered and applied. Extracorporal circulation has developed into a safe standardized method. As far as pathophysiology is concerned, the decision to use ECC or not is of much more importance than the grade of invasiveness. Fundamentally we therefore need to distinguish between minimally invasive methods with and without ECC. Video-assisted coronary surgery in hearts under hypothermia and fibrillation with ECC is also recommended occasionally. Minimally invasive coronary artery procedures on beating hearts without ECC have to be done in a stabilized and bloodless operative field to allow the construction of high standard anastomoses between bypass grafts and coronary arteries. In practice, silicon occluders, epicardial and myocardial suture occlusion and fixation, mechanical stabilization devices, and pharmacologic induction of bradycardia are used. In principle a skilled surgeon should be familiar with all these methods to select the most suitable solution for the special clinical problem. A final judgement about each method is not possible up to now. High patients numbers have to be recruited in the groups and subgroups due to low mortality (1%) and morbidity (5%), otherwise statistical significance of the results cannot be gained.

Humidification of inspired gas in artificially ventilated patients positively influences mucociliary function and secretolysis. We performed this study to examine the properties of heat and moisture exchangers in comparison with hot water humidifiers and dry artificial ventilation. Methods: We measured inspired humidity with a special sensor in 41 patients after coronary artery bypass grafting with cardiopulmonary bypass. Three Heat and Moisture Exchangers (HME) and a hot water humidifier were used to humidify the inspired gas of artificially ventilated patients. Humidity measurements were compared. Results: Hot water humidifiers produced the highest humidification (average of 38.4 mg/l, 37-43 mg/l); lowest humidification was produced by dry artificial ventilation (average of 8.7 mg/l, 6-11 mg/l). Heat and moisture exchangers (HME) produced humidity between 24 and 36 mg/l. Highest humidification was produced by HME hygrobac s(R) (average of 32.2 mg/l, 31-36 mg/l) and hygrovent s(R) (average of 31.4 mg/l, 29-35 mg/l); lowest humidification was produced by HME hygroster(R) (average of 28.6 mg/l, 24-31 mg/). Multifactorial analysis shows a significant impact of the humidification method on the humidity of inspired gas. The multiple comparison procedure (Tukey) shows significant differences (alpha = 0.05) between all humidification techniques on inspired gas except the heat and moisture exchangers hygrobac s(R) and hygrovent s(R). Conclusions: Hygrobac s(R) and hygrovent s(R) may be an alternative to hot water humidifiers. Further clinical studies of HMEs and hot water humidifiers will be necessary to evaluate the influence of inspired gas humidity on the outcome of artificially ventilated patients.

Two types of heparin-associated thrombopenia can be distinguished. Patients with the type II condition present a particularly difficult management problem when they require full anticoagulation. There is no consensus about the proper anticoagulation management for type II patients who have to undergo cardiopulmonary bypass. The case is reported of a type II heparin-associated thrombopenia patient who underwent successful aortocoronary saphenous vein grafting. Sodium-danaparoid was used for anticoagulation. The anti-factor Xa level was kept below the value reported in the literature for patients undergoing cardiopulmonary bypass. No fibrin formation was observed during the time of cardiopulmonary bypass, nor was any severe postoperative haemorrhage seen, as is frequently described in the literature.

Hygrobac s and hygrovent s may be an alternative to hot water humidifiers. Further clinical studies of HMEs and hot water humidifiers will be necessary to evaluate the influence of inspired gas humidity on the outcome of artificially ventilated patients.

Attempted Venous cannulation with a dual-stage cannula for cardiopulmonary bypass in routine coronary revascularization led to the discovery of an abnormal inferior vena cava in a 65-year-old patient. The operative and postoperative course of the patient were not affected by the inferior caval anomaly. The detailed infradiaphragmatic venous anatomy was elucidated later by MRI and showed bilateral inferior caval veins with azygos continuation. Although this malformation of the inferior cava is rare in adults, the occurrence should be known. Quick recognition and handling should be achieved if detected during cannulation for cardiopulmonary bypass.

End-stage renal failure is commonly considered a significant factor for an increased risk after coronary artery bypass grafting. This holds true for patients who have received a kidney transplant (NTX group) as well as for patients who require chronic hemodialysis (HD group). To assess the risk in our population we performed a retrospective analysis of 22 patients with end-stage renal failure (HD group: 17, NTX group: 5) who underwent cardiac surgery. The perioperative course was compared to a normal population. In addition to standard data we assessed the following factors: renal failure etiology, risk factors, concurrent diseases, duration of renal failure, function of renal graft, ECG (paying special attention to signs of previous myocardial infarctions and rhythm disorders), results of cardiac catheterization and coronary angiography, NYHA class and urgency of operative intervention. Complications and mortality were the main measures of the perioperative course. We analyzed the hospital charts retrospectively and requested the patients' physicians to complete a questionnaire about the patient's present condition. All HD group patients were dialyzed on the day before surgery. The first postoperative HD was performed for hyperkalemia or signs of volume overload (pulmonary capillary wedge pressure > 20 mmHg) when signs of pulmonary function deterioration were seen. HD was successful in treating these conditions. 3 of the 17 patients on HD expired postoperatively, 4 died within 3 years, all of unrelated diseases. Mortality and morbidity was 0% in the NTX group. In one NTX patient who required intermittent HD preoperatively because of poor renal graft function, renal function improved postoperatively, presumably secondary to better renal perfusion, and he did not require HD after his cardiac surgery. By surgical intervention the NYHA class of all patients improved (by 1.6 on the average) as well as their quality of life. Because of these good short- and long-term results and relatively low operative risk we support an approach of prompt work-up and surgical intervention when necessary in HD and NTX patients.

Because of the paucity of literature reports about cardiac operations in renal-transplant patients we performed a retrospective study encompassing all such patients operated upon in our institution in 1993 and 1994. During this time 5 renal transplant patients underwent cardiac surgical procedures between 1 and 9 years after transplantation: in 4 patients coronary artery bypass grafting (CABG) was carried out and in one patient aortic valve replacement. We analyzed pre-, peri-, and postoperative data. Late results were obtained by questionnaire from the patients' primary physicians. Short- and long-term results were excellent. Mortality was 0%. At late follow-up (8-23 months) all patients were in NYHA class II or better. Postoperatively all patients experienced a clear improvement of their cardiac symptoms. None of the transplanted kidneys deteriorated. One patient who had to undergo intermittent hemodialysis preoperatively improved so much that she did not require any dialysis postoperatively. Although the total number of patients in this study is limited we believe it can be stated that renal transplant patients can undergo cardiac operations with generally good results.

The amount of particulate matter present in Bretschneider's cardioplegic solution (HTK) was assessed by laser-mediated particle counting. Permissible levels of contaminant particles with a distribution of diameters between 0.2 and 20 microns were found. A significant further increase in the particle count was observed when the fluid was administered for clinical use, which resulted in the additional release of particles from, for example, the infusion kit, which included an in-line filter with pores of 270 microns. Filtration of the HTK solution by a terminal inline filter (0.2 micron) significantly reduced the number of particles. In order to determine the chemical composition and the potential hazards of the particulate material we used scanning electron microscopy in combination with energy dispersive X-ray analysis and transmission electron microscopy to examine specimens taken from heart tissue obtained from Göttinger minipigs after cardioplegia and from humans undergoing mitral valve replacement after cardioplegia and reperfusion. Particles of various diameters were found either to be plugging coronary capillaries, to be adherent to the endothelial layer, or to be engulfed by polymorphonuclear (PMN) granulocytes, which appeared to be activated. Some of the PMN granulocytes were apparent in the endothelial layer. It is recommended, therefore, that a terminal in-line filter (0.2 micron) should be routinely used.

Improvement of interventional techniques, sophisticated patient selection, and individual experience has decreased the probability of emergency operative revascularization of increasing numbers of PTCA cases in recent years. This rate is now between 0.5 to 3%, including highrisk dilatations. Dissection is the most common complication of PTCA, while perforation is rare. Patients with high risk for PTCA-procedures (age, concomittant diseases, female gender) are, in general, risk patients for operative revascularization. The postoperative course of emergency bypass surgery after PTCA-complication (infarction rate, mortality) is dependent on duration and severity of the myocardial ischemia and preoperative circulatory function. Complete revascularization in cases of multi-vessel disease and the use of the internal mammary artery as a graft vessel is being achieved in increasing numbers.

Improvement of interventional techniques, sophisticated patient selection, and individual experience has decreased the probability of emergency operative revascularization of increasing numbers of PTCA cases in recent years. This rate is now between 0.5 to 3%, including highrisk dilatations. Dissection is the most common complication of PTCA, while perforation is rare. Patients with high risk for PTCA-procedures (age, concomittant diseases, female gender) are, in general, risk patients for operative revascularization. The postoperative course of emergency bypass surgery after PTCA-complication (infarction rate, mortality) is dependent on duration and severity of the myocardial ischemia and preoperative circulatory function. Complete revascularization in cases of multi-vessel disease and the use of the internal mammary artery as a graft vessel is being achieved in increasing numbers.

We examined 20 patients undergoing coronary bypass grafting for coronary artery disease with NYHA classifications of II and III who had been treated with beta-blocking agents. Patients were randomised for administration of either adrenaline (0.1 microgram/kg/min) or amrinone (bolus 1 mg/kg, continuous infusion of 5-10 micrograms/kg/min), if following cardiopulmonary bypass their cardiac index was < 2.4 L/min/m2 with normal peripheral resistance and normal or increased right- or left-ventricular filling pressures. Over a period of 1 hour, the hemodynamic parameters mean arterial pressure (MAP), cardiac index (CI), heart rate (HR), coronary perfusion pressure (CPP), total peripheral resistance (TPR), as well as the pressure-work index (PWI) were registered or calculated. By means of a coronary sinus catheter myocardial arterio-venous oxygen content difference (AVDO2cor), myocardial blood flow (MBF), using the thermodilution method, and myocardial oxygen consumption (MVO2) could be measured or calculated. Simultaneously, arterial and myocardial lactate concentrations and, using the arterio-venous lactate ratio, myocardial lactate extraction or production were quantified. Using a transseptal approach, the left-ventricular pressure curve was measured and used to differentiate for myocardial contractility (dp/dtmax). Following induction of anesthesia and after cardiopulmonary bypass, plasma levels of the used beta-blocking agent were determined. Both substances caused a significant increase in myocardial contractility, with adrenaline showing a more potent effect than amrinone. Both substances caused a significant increase in CI with a mild increase in HR. Amrinone caused a significant drop in TPR, while MAP remained practically constant.(ABSTRACT TRUNCATED AT 250 WORDS)

Chylothorax may be a rare problem in thoracic and cardiovascular surgery, but it is one which is often difficult to handle. The therapeutic procedure required in each individual case is determined by the anatomy and physiology of the ductus thoracicus and the individual etiology of the chylothorax. The ductus thoracicus runs from the cysterna chilii through the right hemithorax in a dorsolateral position relative to the hiatus aortae, crossing over to the left at the height of the fourth thoracic vertebra and passing to the left supraclavicular venous angle. Major pathogenetic features of the duct are its variability, the large number of collaterals, and the variety of lymphaticovenous anastomoses found. Lymph flow at peak pressures up to 25 cm H2O is tolerated; at higher pressures the duct or its collaterals rupture. In terms of etiology, two groups may be distinguished: (a) traumatic or iatrogenic causes, i.e., direct punctual lesions, and (b) chylothorax of neoplastic origin, caused either by direct destruction by the tumor or by ruptures of the collaterals or intrathoracic lymphaticovenous anastomoses due to increased intraductal pressure. The absolute incidence of chylothorax remains at a constant low level. Over a period of 20 years the Mayo Clinic reports only 53 cases; at our clinic we have treated a total of 9 cases in the past 10 years. Our therapeutic approach, which is based on pathophysiological and anatomical considerations, is as follows: (a) Primary attempt at conservative treatment: parenteral feeding with a fat-free diet using a gastric tube (!) to relieve the stomach combined with Buelau drainage with a low suction. (b) In the case of traumatic or operative/iatrogenic chylothorax, the direct suture or supradiaphragmal ligature (Lampson) may be used; the possibility of the complication of chyloperitoneum must, however, be considered if there is a lack of collaterals. (c) In the case of severe localized obstruction due to tumor growth, relapse due to increased pressure in the collaterals is very probable. In such cases it is better to cover the rupture directly with autologous or xenogenic material and to seal it with fibrin glue. Fibrin glue appears helpful in providing an absolutely tight seal against fatty fluids in the area of the leakage for 1–2 days until the area is further sealed by cicatrization due to incipient healing and conversion processes. We see our concept as a promising additive to surgery, which can reduce the complication rate in the case of chylothorax caused by tumors with high secretion rates.

A significant proportion of early graft occlusions after aortocoronary revascularization using autologous saphenous vein grafts (SVG) are due to mechanical and/or metabolic or biochemical endothelial lesions. The morphological examination of the endothelium, usually carried out using light microscopy or by various types of scanning electron microscopy (SEM), does not give any indication of the functioning of the endothelium (E). Functionally intact E is capable of producing endothelium-derived relaxing factor (EDRF); a practicable in vitro test is the relaxation of pre-contracted vein segments (VS) in response to acetylcholine (ACh) application. To study the effect of the solution used to rinse and store the SVG between removal and implantation on the functional characteristics of the E, we performed in vitro tests on macroscopically intact VS removed from the saphenous vein of 30 male patients who underwent elective CABG surgery. Isolated VS rings were incubated for 60 min in heparinized whole blood (HWB), Bretschneider's cardioplegic solution (HTK), human albumin solution (HAS), or Ringer's solution (RS) and compared with the results obtained immediately after the removal of untreated control samples (C) taken from the same patients. After equilibration in carbogen aerated Krebs-Henseleit solution and precontraction by 3 x 10(-7) M noradrenaline (NE), relaxation induced by 10(-6) M ACh was measured. Only the samples stored in HWB (13.4 +/- 0.4 mN) showed similar maximal contractions with NE to those in the control group (14.4 +/- 0.5 mN), i.e. all those segments which showed both contractions with NE and relaxation with ACh.(ABSTRACT TRUNCATED AT 250 WORDS)