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Die Entwicklungen in der Herzschrittmacher- und ICD-Therapie in den letzten Jahren sind durch steigende Implantationszahlen (insbesondere bei ICD- und CRT-Systemen) und eine zunehmende Komplexitat der Aggregate gekennzeichnet. Probleme ergeben sich aus der grosen Anzahl notwendiger Nachkontrollen sowie in Bezug auf die Patientensicherheit und das Device-Management durch spezialisierte Arzte. Die telemedizinische Uberwachung kann hier Losungsansatze bieten. Die Hersteller haben praxistaugliche Systemlosungen fur das Telemonitoring von Patienten mit Herzschrittmachern, ICDs und CRT-Systemen entwickelt. Die Systeme bestehen aus dem Implantat mit automatischer oder manueller Datenubertragung, einem Patientenmonitor mit Datenubertragung (Mobilfunk, Festnetz), dem Datenserver und der Datenprasentation (Internetplattform) fur den Arzt. In verschiedenen klinischen Studien wurde die Stabilitat und Sicherheit der Datenubertragung nachgewiesen. Durch das telemedizinische Monitoring kann die Uberwachung der Patienten (z. B. Patienten mit CRT-Systemen wegen chronischer Herzinsuffizienz) und das Arrhythmie-Management (z. B. bei Patienten mit paroxysmalem Vorhofflimmern) verbessert werden. Das Telemonitoring macht auch eine Individualisierung der Nachkontrollintervalle moglich, was zu einer Kostenersparnis fuhrt. Die telemedizinische Uberwachung von Patienten mit ICD- und CRT-Systemen eroffnet neue Moglichkeiten zur vernetzten Nachsorge und umfassenden medizinischen Betreuung.

Die Herzinsuffizienz stellt ein bedeutendes klinisches und gesundheitsokonomisches Problem dar. Die Umsetzung neuer, den Krankheitsverlauf gunstig beeinflussender Therapiestrategien und der hieraus resultierenden Therapieleitlinien in der chronischen Herzinsuffizienz sind im Praxisalltag nach wie vor unzureichend. Der Einsatz der Telemedizin bietet sich daher als zentrales Service- und Informationsinstrument an, so dass durch eine konsequente Uberwachung des chronisch herzkranken Patienten eine optimierte Therapiefuhrung ermoglicht wird. Vorgegebene Vitalparameter werden automatisch an das telemedizinische Zentrum ubermittelt, bei Uberschreitung individuell festgelegter Grenzwerte werden umgehend therapeutische Masnahmen eingeleitet. Bei kardiopulmonalen Symptomen ist das Zentrum an 24 h fur 365 Tagen im Jahr fur den Patienten erreichbar. Dieser patientenorientierte Technologieeinsatz sollte dabei die Arzt-Patientenbeziehung nicht ersetzen, sondern verbessert und fordert die Partizipation sowie das Selbstmanagement der Patientinnen und Patienten. Auserdem zeigen die Ergebnisse, dass durch diese Technologie die Zahl der Notarzteinsatze, Klinikeinweisungen und Arztbesuche hochsignifikant reduziert werden kann und aus gesundheitsokonomischer Sicht, auch unter Berucksichtigung der systemimmanenten Mehrkosten, die eindeutig kosteneffektivere Behandlungsstrategie darstellt. Der Einsatz der Telemedizin bei chronisch herzinsuffizienten Patienten konnte somit eine zukunftsweisende Betreuungsform darstellen, durch die der Informations- und Datenfluss zwischen Patient, Krankenhaus und niedergelassenem Arzt entscheidend individuell und zu jeder Zeit optimiert werden kann.

In 150 konsekutiven Patienten, die einer elektiven oder notfallmasigen aortokoronaren Bypass-Operation unterzogen wurden, wurde die Vena saphena magna mittels einer einfachen, minimal-invasiven, nicht-endoskopischen Praparationstechnik entnommen. Aufgrund der klinischen Resultate mit Berucksichtigung der individuellen Anwendbarkeit, der Saphenektomie bezogenen Morbiditat, des kosmetisch-asthetischen Faktors, sowie auch des generellen Outcomes empfehlen wir diese Technik vorbehaltlos zur routinemasigen Anwendung bei Elektiv- und Notfalleingriffen.

A reciprocal translocation 60,XX,t(X;1)(42;13) was detected in a 2-month-old chimeric calf. A study of the parents of the calf strongly suggested the 'de novo' origin of the aberration. © Inra/Elsevier, Paris

Eine alternative, simplifizierte Technik der Mitralklappen-Anuloplastik fur bestimmte Indikationsbereiche wird vorgestellt und die Vorteile insbesondere im Vergleich zum kommerziellen Anuloplastie-Ring diskutiert.

Telemedizin beschreibt den Einsatz multimedialer Kommunikations- und Informationstechnologien im Gesundheitswesen. Durch die Uberbruckung der raumlichen Trennung zwischen Arzt und Patient,kann beispielsweise in der Kardiologie ein Monitoring von EKG und Blutdruck erfolgen. Die Messwerte werden in einem telemedizinischen Zentrum von Fachleuten interpretiert, sodass gegebenenfalls notwendige Therapiemasnahmen eingeleitet werden konnen. Die Analyse erster Erfahrungen mit einer transtelefonischen 12-Kanal-EKG-Ubertragung zeigt eine hohe Rate (70%) klassischer kardiopulmonaler Beschwerden bei einer erstaunlich hohen Rate von neu aufgetretenen zusatzlichen Befunden (25%).Nur in 20% der Falle musste eine Notfalltherapie eingeleitet werden, die zur Stabilisierung bis zum Eintreffen des Notarztes fuhrte.Auffallend ist insbesondere der Zeitgewinn, der durch das Telemonitoring erreicht werden kann. Zukunftige Studien mussen zeigen, ob neben der Verbesserung der Patientenbetreuung auch eine Kostensenkung moglich ist.

Recent developments in pacemaker and ICD therapy can be characterized by a rising number of implantations (especially in the field of ICD and CRT systems) and an increasing complexity of the units involved. Problems evolving from this trend are the soaring numbers of necessary follow-up examinations, issues of patient safety and the necessity of device management by specialized physicians. Telemonitoring offers various possibilities of improvement in these areas. The manufacturers of the devices have developed applicable solutions for concepts of care including telemedical monitoring of patients with pacemakers, ICD and CRT systems. The systems commonly include an implant capable of either automatic or manual data transmission, a device for transmitting the implant's data (mobile communication or fixed line network), a server managing the information and a front-end (internet-based) platform for the physician. Multiple clinical trials have verified the stability and the security of this method of data transmission. Telemedical monitoring can be used in order to improve the monitoring of the patients' state of health (e. g., patients with CRT systems because of their CHF) and the management of arrhythmias (e. g., patients suffering from paroxysmal atrial fibrillation). Telemonitoring allows the intervals between follow-up check-ups to be individualized, thus, leading to financial savings. The telemedical monitoring of patients with ICD and CRT systems facilitates new opportunities for networked follow-up care and comprehensive medical treatment.

Because tracer techniques are gaining an increasing importance for imaging flow (and metabolism) in the heart, experimental evidence is needed on the role of convection and diffusion in the transcoronary transport of solutes. In the present work, the transport of four different inert gases through the coronary system is studied in five closed-chest dog experiments and is compared with a digital multicapillary convection-diffusion model. Transport may be defined as flow dependent, as judged by the gross similarity of shape of the time-normalized dilution curves. However, the results show that the transcoronary transport of helium and xenon is more dispersed than that of argon and krypton, probably because of differences in diffusibility and solubility. A comparison of the animal and model experiments emphasizes the importance of diffusive transport of the gases. It is suggested that there is a diffusion shunt that is mainly located within the capillary network itself rather than between conduit vessels. Only for helium (which has the highest diffusivity) was a small arteriovenous shunt fraction seen that is thought to bypass the capillary exchange region. The conclusion is that although there is evidence of diffusional shunting at a capillary level, the inert gas kinetics in the heart are compatible with a basically flow-limited transport.

Bovine follicular oocytes were matured in TCM 199 supplemented with: (1) fetal calf serum (FCS, 20% v/v), Luteinizing Hormone (LH, 10 ug/ml), and Estradiol-17-beta (E(2), 1 ug/ml) in Experiment 1; (2) 20% cow serum recovered at standing estrus (Experiment 2); or (3) 20% FCS (Experiment 3). Maturation, fertilization, and initial cleavage development were evaluated at 16 and 48 h after in vitro insemination. The proportions of oocytes fertilized after maturation in the presence of added hormones (78.5%, Experiment 1) or estrous serum (71.3%, Experiment 2) were significantly higher (p < 0.01) than after use of FCS alone (39.3%, Experiment 3). Cleavage of zygotes within 48 h post-insemination differed significantly (p < 0.01) between maturation treatments, 27.3%, 75.5% and 6.6% for Experiments 1, 2, and 3, respectively. Results demonstrate a beneficial influence of estrous cow serum, characterized by an elevated concentration of LH, on bovine oocyte maturation in vitro.

An increasing number of older patients undergo cardiac surgery. Complications after cardiac surgery such as rhythm disorders, myocardial infarction and atypical symptoms frequently lead to ambulatory visits and hospitalisations. Telemonitoring might be one method for rapid and efficient detection and classification of symptoms. We examined in this pilot study if ECG-telemonitoring after cardiac surgery proves to be an useful, reliable and accepted procedure with respect to cost and risk reduction.Two hundred eight patients (46 female, 162 male) received after surgery an individually adjusted portable 12-lead ECG-monitor. Within three months all incoming ECG-recordings were analysed. In total, 1387 calls from 165 patients (80% use) with ECG-recording (8,4 calls per patient) were collected. There were 235 calls (17%) because of symptoms, 51% of them were registered between 6 PM and 8 AM. Fourteen (6%) out of those 235 emergency calls with ECG-registration led to hospitalisation (n=5) or ambulatory visits next day. The remaining 221 ECG showed no pathological ECG-signs and the patients could be managed with telephonic advice, reassurance and telemedical follow up. Readmissions were due to angina pectoris, severe but unspecific chest pain and cardiac decompensation (n=3) as well as rhythm disturbances (n=2). Almost 75% of all emergency calls were recorded within the first 60 min after the onset of symptoms.Older patients reproducibly are able to telemetrically transmit electrocardiograms after a short training before discharged home. Although there is a low incidence of complications among our study population, telemedical ECG-monitoring rapidly helps to differentiate between the symptoms leading to increased patient safety and prevented further damage. The reduction of ambulatory visits and hospitalisations only for treatment of objectified symptoms may lead to a overall cost reduction in the health care system. The reduction of unnecessary hospitalisations and ambulatory visits might also contribute to an optimised time management.

Heart failure exhibits a significant clinical and health economic problem. The implementation of new therapeutic strategies favorably affecting the course of disease is still insufficient in day-to-day practice. Thus, the usage of telemedicine offers a central instrument for service and information, so that an optimized therapy can be achieved by consequent surveillance of the patient with chronic heart disease. Predefined vital parameters are automatically transmitted to the telemedicine center; if individually predefined limits are exceeded, therapeutic means are immediately initiated. For the patient, the center is attainable 24 h throughout the year in case he experiences cardio-pulmonary symptoms. This patient-oriented usage of technology should not replace the physician-patient relationship, but improves and supports the participation and self-management of patients. Furthermore, the results show that this technology can significantly reduce the amount of emergency physician services, hospital admissions and primary care physician visits, and displays for health economics purposes a clearly more cost-effective treatment strategy, while allowing for additional costs inherent to the system. The usage of telemonitoring in chronic heart failure patients may be a trendsetting form of care, which can be used to drastically optimize the information and data flow between patient, hospital and primary care physician individually and at any time.

The aim of the study was to investigate the developmental pattern of hypoplastic pulmonary artery (p.a.) bed augmented by systemic-to-pulmonary shunt in children with univentricular heart scheduled for Fontan surgery. For the study, a highly selected patient cohort was chosen (12 patients aged between 5 and 19 years; mean 9.5 years) with comparable initial morphological conditions of univentricular heart and hypoplastic p.a. bed, who after mandatory systemic-to-pulmonary shunt underwent Fontan procedure at time of normalization of pulmonary artery size. Further selection criteria were: normal pulmonary vascular resistance at time of Fontan procedure, competent a-v valve(s), and globally unimpaired ventricular function. All patients were grouped according to the preoperative pulmonary flow index (Qpi; L/min/m2 b.s.a.) measured immediately before Fontan operation: Group A: 1.5-2.5; B: 3.0-4.0; C: 4.0-5.0; D:6.0, and their cardio-pulmonary hemodynamic situation (Hb, SAsat%, Qp/Qs, PAP, Rp/Rs, EDVP, FS%, ventricular diastolic compliance (VC = EDVP/Qpi + Qsi) as well as the pulmonary artery size and area using standard (Nakata-index, McGoon-ratio) and a self designed computer assisted planimetric area calculation (PPAAI; cm2/m2 b.s.a.) analysed. Each patient underwent 1-3 shunt procedures, the mean shunt patency period for groups A, B, C and D was 12, 8.6, 5.3, and 4.5 years, respectively. The mean Nakata-index (283, 297, 324, 405 in groups A-D) and the McGoon-ratio (2.0, 2.2, 2.8, 3.3 in groups A-D) correlated with the Qp index, reflecting flow dependent development of pulmonary artery bed. No correlation was found between Qpi and PPAAI (47, 40, 41 and 47 in group A-D). The VC/Qp relation showed an inversely proportional pattern with values 2.3, 1.0, 0.8, 0.7 for corresponding groups A-D, the lowest VC in group A correlated with polyglobulic status (Hb- values; g/dl): 21.3 in A vs 19.8, 18.0 and 16.5 in B-D) and mean arterial SAsat-values (77% in A vs 83%, 84% and 89% in B-D). In conclusion, in our highly selected patient cohort, the development of p.a. size was strongly flow-dependent, and patients with restrictive pulmonary flow needed an approximately threefold longer time period to normalize their p.a. size compared to those with excessive flow. In patients with restrictive pulmonary flow, the Nakata-index underestimated the degree of development of the pulmonary artery system, probably due to the distortion of the proximal p.a. segment. In consequence, in these patients the normalization of the p.a. bed and thus suitability for the Fontan procedure probably occurred much earlier. Based on our observations and those of others, in patients with excessive flow the normalization of p.a. bed, provided it occurs within 3-4 years, seems not necessarily to be associated with a deterioration of ventricular function.

A new kind of silicon wafer and a new class of materials engineering techniques for silicon wafers is described. This wafer, called the “Magic Denuded Zone” or MDZ wafer, is produced through the manipulation of the vacancy concentration and, in particular, vacancy concentration depth profiles in the wafer prior to the development of oxygen precipitates in subsequent heat treatments. The result is a wafer with ideal oxygen precipitation behavior for use in all types of integrated circuit applications. The methods used to prepare such wafers combine Frenkel pair generation with injection and the use of surface sinks. Simulations of the vacancy profiles produced by these techniques are presented and discussed. It is shown that within the range of vacancy concentration accessible by these techniques (up to ca. 1013 cm−3) the rate and oxygen concentration dependence of oxygen clustering can be substantially modified. Such techniques can be used to precisely engineer unique and desirable oxygen-related defect performance in silicon wafers both in terms of distribution and rate of defect formation. One result of the application of such techniques is an ideally precipitating silicon wafer in which the resulting oxygen precipitate profile (denuded zone depth and bulk density of precipitates) is independent of the concentration of oxygen of the wafer, the details of the crystal growth process used to prepare the wafer and, to a very large extent, the details of thermal cycles used to process the wafer into an electronic device. Optimal, generic and reliable internal gettering performance is achieved in such a wafer

The aim of the study was to validate clinically a new technique of myocardial protection developed for intra- and extra-cardiac surgery on the beating heart. The concept combines the principle of continuous pressure- and volume-controlled coronary artery perfusion (PVC-CONTHY-CAP) with the specific myocardioprotective effects of hypothermia and nitrates and, on the other hand, with the beta-blocker-mediated reduction of chronotropy and inotropy necessary for convenient surgery. Under standard ECC conditions after cross-clamping the aorta coronary perfusion with oxygenated blood enriched with nitroglycerine (10 micrograms/kg/h) and esmolol (0.05 mg/ml flow/min) is started via an additional perfusion cannula placed in the aortic root. The temperature of the perfusate is maintained at 32 degrees C, the intraaortic pressure at 40-70 mmHg and the perfusion flow in the range 0.8-1.0 ml/g heart muscle/min. In CABG procedures an additional perfusion catheter is used for perfusion of distal coronary artery segments. Using this technique 100 consecutive patients, adults and children, were operated on between 2/96 and 8/96. In 84 adult patients (age: 45-82 yrs), 78 CABG procedures (54 elective, 13 urgent, 11 acute) with a mean bypass count of 3.7 (range 1-7), 69 ITA grafts, 72 grafts to CX, and 3 MVRec/MVRpl, and 6 pure MVRec/MVRpl procedures (1 urgent, 1 emergency) were performed. The mean coronary perfusion time was 48 min (range 21-88 min). In 5 patients perioperative infarction (CABG; 1 emergency after PTCA, 4 elective) with significant increase of CK-MB values (57-98 U/L) occurred. In the 4 elective patients (3 with diabetes mellitus) re-intervention was not possible due to small-vessel disease. In one patient with preoperative infarction IABP was necessary. No patient died. There were 16 children (age: 4weeks-16 yrs): VSD, n = 6, AV-C, n = 2, TOF, n = 1, MVRec, n = 1, DORV (Rastelli), n = 2, SV (TCPC), n = 3, and PV obstruction, n = 1. The mean coronary perfusion time was 97 min (range: 27-260 min). The mean ICU stay 3.9 d (range: 1-10 d). One child died (TCPC) on the 10th postoperative day due to multi-organ failure. In conclusion, PVC-CONTHY-CAP is designed especially for emergency and urgent procedures, i.e. patients with PTCA-related complications, patients with severely depressed LV function, and patients with complex congenital cyanotic heart defects. Using PVC-CONTHY-CAP, coronary artery bypass grafting as well as intracardiac procedures for congenital and acquired heart defects can be performed safely and conveniently, the system is easy to handle for both the cardiac surgeon and perfusionist. Due to its pharmacological properties continuous intracoronary application of nitrates in combination with hypothermia seems to be essential as a preventive treatment modality for the ischemic state.

In cardiac surgery, ventricular assist devices for mechanical circulatory support are implanted for short or mid-term use in patients with therapy refractory postoperative low-output-syndrome to overtake the function of the left, right or of both ventricles until recovery of myocardium can be achieved. In the long-term, these systems are in use as a bridge to transplantation. An increasing number of clinical reports clearly demonstrates that ventricular assist devices can guarantee in a relatively high percentage of patients with postoperative low-output-syndrome a sufficient regeneration of the cardiac function with satisfactory functional and hemodynamic long-term results. Furthermore, a high percentage of patients bridged to transplantation can be successfully transplanted with good clinical outcome and survival rates.

In cardiac surgery mechanical circulatory support with intra-aortic balloon counterpulsation (IABP) is an established measure for the therapy of perioperative low-output-syndrome and refractory cardiogenic shock. The favourable influence on the myocardial oxygen supply and demand-relationship with an improvement of the energetic balance guarantees the functional and ultrastructural recovery of reversibly damaged ischemic myocardium. The efficacy of IABP is uncontradicted and verified by high survival rates even in patients with severe impairment of the ventricular function. The system is easy to applicate by standardized surgical techniques of im- and explantation, safely to handle due to improvements of the technical equipment and can be applied at a low risk.

Cryopreserved venous segments could be used as allografts in coronary by-pass surgery in patients with limited availability of venous or arterial conduits for autologous grafting. After primarily disappointing clinical results it was the aim of these experiments to improve freezing procedure and incubation media in order to maintain most of the functional integrity of the biological material after cryopreservation, and thus to contribute to the essential prerequisites for a successful implantation. Freshly prepared segments of human saphenous vein were cryopreserved: 1) using various computer-assisted freezing programs with definite cooling rates and seeding temperatures; 2) after incubation in media consisting of RPMI 1640 and cryoprotective agents in different combinations and concentrations. The veins were stored at -196 degrees C, thawed quickly and analyzed in an in vitro perfusion system. The degree of vitality of the vein segments was assessed by measuring vasoconstriction after application of Norepinephrine and Serotonine and vasodilatation following release of endothelium-derived relaxing factor (EDRF) after perfusion with Acetylcholine. Our results show that the preservation of vascular smooth muscle can be maintained only by: 1) equilibrating the vein in RPMI 1640 with 2.2 M Glycerol and 1.6 M Ethylene-Glycol and 2) preventing an increase of temperature during the crystallization in the cooling process. The results clearly demonstrate the maintainance of vitality in vein segments after an appropriate freezing and equilibration process with specific cryoprotective agents. The data obtained in the study could serve as the basis for a better longterm prognosis of transplanted cryopreserved venous allografts.

Megakaryocytes are difficult to isolate because of their fragility, their tendency to aggregate, and their varying sizes. For purification of cells at different stages of maturation and of different sizes (ploidy classes) we developed an immunomagnetic cell sorting method (MACS) to enrich the whole spectrum of the megakaryocytic cell lineage. The use of small magnetic beads coupled to various antibodies and labelling with fluorescent antibodies allowed direct analysis of enrichment and evaluation of the isolated fraction without further staining or detachment procedures. CD 61 (Y2/51), a monoclonal antibody directed against platelet glycoprotein IIIa, was employed to perform the separation procedure. An enrichment up to 47% of CD 61-positive cells with an average of 37% and a recovery rate of 37% was obtained by using the MACS technique. Pre-enrichment by Percoll density centrifugation, followed by MACS separation, resulted in an enrichment of 65% and a recovery rate of 67%. The relative amount of small megakaryocytic cells in only MACS-enriched cell populations, however, was higher than in Percoll/MACS fractions. As a parameter of vitality we tested cytokine secretion of the enriched megakaryocytes in reverse haemolytic plaque assays. Secretion of IL-1, IL-6, GM-CSF, and PDGF with and without stimulation by phorbol myristate acetate was demonstrable at the single cell level.

Die intraaortale Ballongegenpulsation (IABP) hat sich im Laufe von mehr als zwei Jahrzehnten zu einer adaquaten Therapieform des perioperativen Low-output-Syndroms sowie des therapierefraktaren kardiogenen Schocks nach Myokardinfarkt im Erwachsenenalter entwickelt [4]. Demgegenuber gibt es vergleichsweise nur wenige Studien uber den Einsatz der IABP im Neugeborenen- und Kindesalter. Dies durfte einerseits darin begrundet sein, das besondere Anforderungen an das technische Material gestellt werden, und andererseits in der Tatsache, das es im Gegensatz zu den Erwachsenen nur wenige in Frage kommende padiatrische Patienten gibt. Dadurch kommt es, das nur wenige Zentren umfangreiche Erfahrungen in der Anwendung der Ballonpumpe im Kindesalter besitzen. Eindrucksvolle Zahlen ergeben sich aus einer amerikanischen Erhebung von Veasy [11] im Jahre 1984, in der von insgesamt 47 Instituten mit speziellen kinderkardiologischen Abteilungen lediglich 25% Erfahrungen mit der IABP aufwiesen. Zusammengefast waren weniger als 40 Patienten mit der Ballonpumpe behandelt worden.

In der Bundesrepublik werden jahrlich etwa 45 000 Operationen am Herzen durchgefuhrt. In etwa 10% aller Falle kommt es dabei zu Problemen beim Abgang von der extrakorporalen Zirkulation (EKZ). Die uberwiegende Mehrzahl dieser Patienten kann allerdings rein pharmakologisch stabilisiert werden, 2–3% bedurfen zusatzlich der intraaortalen Ballongegenpusation (IABP). Nur etwa 0,5–1% der Patienten konnen auch mit Hilfe der IABP nicht ausreichend unterstutzt werden und benotigen ein hamodynamisch wirksameres System der Kreislaufentlastung im Sinne eines links-, rechts- oder biventrikularen Assistenzsystems.

Die mechanische Kreislaufunterstutzung mit univentrikularen Assistenzsystemen hat sich im Erwachsenenalter als Behandlungsprinzip beim therapierefraktaren, postoperativen Low-output-Syndrom etabliert (zur Ubersicht siehe [5]). Im Gegensatz dazu sind im Bereich der kongenitalen Herzchirurgie im Sauglings- und Neugeborenenalter die Erfahrungen begrenzt und beschranken sich auf nur wenige Falle. In der Regel wird eine biventrikulare Kreislaufunterstutzung mit venoarteriellem Bypass und extrakorporaler Membranoxygenierung (ECMO) bevorzugt [1, 3, 4, 9], extrem selten werden offensichtlich univentrikulare Assistenzsysteme mit pulsatilem bzw. nichtpulsatilem Flusmuster eingesetzt [2, 7, 8].

Seit der ersten klinischen Anwendung durch Kantrowitz im Jahre 1968 [2] hat sich die intraaortale Ballongegenpulsation im Bereich der Herzchirurgie zu einem etablierten Behandlungsprinzip bei postoperativem Low-output-Syndrom entwickelt. Die Indikation zur assistierten Zirkulation mittels IABP ist nach Eingriffen am Herzen gegeben, wenn sich die kardiale Situation trotz Ausschopfung aller pharmakologischen Moglichkeiten und adaquater Nachperfusion nicht soweit stabilisieren last, das ein Herzindex uber 2 1/min × m2, ein systolischer Aortendruck uber 90 mm Hg, ein linksatrialer bzw. Pulmonalkapillardruck unter 20 mm Hg und eine Urinproduktion uber 1 ml/kg × h erreicht werden [3]. Derartige hamodynamische Konstellationen finden sich nach vorsichtigen Schatzungen bei etwa 1–2% aller herzchirurgischen Patienten, bei weiteren 0,5–1% wird der Einsatz des Systems nach gleichen Kriterien erst im spateren postoperativen Verlauf notwendig.

In anesthesiology and intensive care medicine it is often necessary to treat disorders involving cardiac failure or low-output syndrome. However, in patients who are endangered by ischemic heart disease, any pharmacologic therapy with positive inotropic agents should improve cardiac output without increasing myocardial oxygen demand significantly: the heart should perform its task as efficiently as possible. In the present study a mathematical model of myocardial efficiency was developed. The implications of this theoretical concept of myocardial efficiency were evaluated in animal experiments. THEORETICAL MODEL. Cardiac efficiency is predominantly dependent on preload, afterload, and inotropic state. Quantitatively, it can be calculated from end-diastolic volume, left ventricular systolic pressure (Psyst), stroke volume (SV), and ejection time. The implications of the theoretical analysis are: (1) the inotropic state, which leads to optimal myocardial efficiency, is specifically determined by preload and afterload: for each preload and afterload one matched inotropic state is necessary to achieve optimal efficiency; (2) an increase in blood pressure leads to a decrease in myocardial efficiency even if the inotropic state is optimally matched to preload and afterload; and (3) an increase in end-diastolic volume improves the efficiency of myocardial pump work. ANIMAL EXPERIMENTS. The validity of the theoretical model was studied in animal experiments with emphasis on the following items: (1) is theoretically optimal efficiency of myocardial pump work achieved by physiologic regulation of myocardial performance? (2) how does sympathetic stimulation influence myocardial efficiency? and (3) how do cardiodepressive agents such as beta-blockers or volatile anesthetics influence myocardial efficiency? METHODS. Experiments were performed on nine mongrel dogs after induction of piritramide--nitrous oxide anesthesia. Standard hemodynamics: heart rate, Psyst, maximum left ventricular pressure rise (dP/dtmax), and SV (thermodilution) as well as coronary blood flow (pressure difference catheter) and myocardial oxygen consumption (Fick principle) were measured. In order to create a broad range of different hemodynamic settings, blood withdrawal and retransfusion of blood and/or colloid osmotic solutions were used to modify intravascular volume. Additionally, the inotropic state was varied by infusion of catecholamines (isoproterenol 0.4-0.8 microgram.kg-1.min-1 or norepinephrine 1-2 micrograms.kg-1.min-1). Experimental myocardial failure was induced by adding halothane (0.8-1.5 MAC) to the basic anesthesia, beta-blockade with propranolol (125-250 micrograms.kg-1), and combination of beta-blockade with a pressure load imposed on the myocardium (propranolol 125-250 micrograms.kg-1 + norepinephrine 1-2 micrograms.kg-1.min-1). RESULTS. During variation of the intravascular blood volume by normo-, hypo-, and hypervolemia, the myocardial efficiency very closely matched the theoretically predicted values of optimal efficiency: the average observed efficiency was 98.8% of predicted optimal efficiency. Increasing afterload with norepinephrine did not alter this close relationship, although absolute values of efficiency decreased as predicted by the theoretical model. Application of isoproterenol resulted in SVs that exceeded optimal values by 41.5%. In contrast, during experimental myocardial failure SVs were too small to achieve the necessary values for optimal pump work; observed myocardial efficiency was therefore significantly lower than optimal efficiency. CONCLUSIONS. For pharmacological interventions, it can be concluded that maximal efficiency of cardiac pump work requires maximal end-diastolic filling in combination with minimal afterload. (ABSTRACT TRUNCATED AT 400 WORDS)

Since the inception of coronary artery bypass grafting, refinements in surgical technique, myocardial preservation, anesthesia and in pre- and postoperative care, reduced the perioperative mortality and improved the long-term results in patients with chronic coronary artery disease. Large-scale, multicentre randomized and a multitude of non-randomized clinical trials of surgical versus medical treatment have set therapeutic standards for quality and refined the indications for bypass surgery. In summary, these studies clearly indicate that surgery is superior to medical therapy in symptom relief, decreased antianginal drug use and improved exercise performance, but does not improve the likelihood of return to employment, non-fatal myocardial infarction prevalence or hospitalization rates. After surgery, survival is prolonged in those subsets of patients who are considered at high risk, i.e. patients with left main disease (greater than 70%), with two-vessel disease with severe left anterior descending artery stenosis or with three-vessel disease with signs of significant ischemia on exercise or left ventricular dysfunction present. Specific individual risk profiles during coronary artery surgery were evaluated by a multicentre retrospective analysis of 8363 patients (QuaDRA-study) documenting a significantly higher perioperative letality and incidence of postoperative complications (low output syndrome, infection, renal dysfunction, psychosyndrome) in the elderly (greater than 65 years).

The aim of this study was to examine whether myocardial function can be maintained by a catheter system designed for coronary autoperfusion in emergency cases due to coronary artery obstruction (CAO) after failed PTCA.

We have undertaken a randomized study on 20 patients undergoing coronary artery bypass surgery in order to determine the influence of cardiopulmonary pump prime solutions on colloid osmotic pressure and extravascular lung water. Crystalloid priming with Ringer lactate was compared with an albumin solution of nearly physiological colloid osmotic composition (4%). Measurements of extravascular lung water were performed by a modified, highly sensitive thermal dye technique, with additional detection of tracer signals in the pulmonary artery. In the Ringer lactate group, a significantly greater decrease in colloid osmotic pressure occurred immediately after onset of cardiopulmonary bypass. The more pronounced decrease in colloid osmotic pressure and in transcapillary gradient (difference between colloid osmotic pressure and pulmonary capillary wedge pressure) in the Ringer lactate group was associated with a significant increase in extravascular lung water (by 60%) in the postoperative period; the human albumin group, however, showed only a slight tendency to increased lung water. There were no differences in haemodynamic or respiratory states after operation.

We studied the heterogeneity of myocardial blood flow in nine anesthetized closed-chest dogs using an indicator-dilution technique that allows the stochastic description of transport characteristics for three inert gases (helium, argon, and xenon) from the coronary inflow to outflow. The results show that under normal conditions the transcoronary transport of the tracers is spatially heterogeneous. Heterogeneity is strongly dependent on the arterial oxygen tension over a range of 40–200 Torr. This could be similarly observed with each tracer gas despite different physicochemical properties and was largely independent from the magnitude of coronary blood flow. The results are interpreted to mean that the arteriolar or intratissue PO2 influences myocardial blood flow over a broad range and possibly acts as an important integrating factor in the local regulation of coronary blood flow and flow reserve.

The combination of temperature and various intravascular indicators [4, 6, 9, 10, 11, 13] has been used since 1966 [12] to determine extravascular lung thermal volume, which is a measure of “true” pulmonary extravascular water. Probably the best estimates of pulmonary extravascular water are available from gravimetric techniques and range from 4 to 5 ml/kg [13, 14]. In contrast, extravascular lung thermal volume, as reported from different laboratories, is in the order of 6–10 ml/kg [4, 6, 9, 10, 11, 12, 13]. The possibility that the thermal indicator equilibrates with extrapulmonary structures like right and left myocardium has been discussed in the literature [6, 9, 11, 14, 15]. The adequacy of monoexponential extrapolation to clear the dilution curves from the effects of indicator recirculation has so far been assumed but not verified.

Temporary cardiac pacing (CP) is frequently applied postoperatively in the management of low cardiac output (CO) and rhythm instability. However, uncertainty exists about the "optimal" pacing rate, range and mode due to incomplete information on myocardial oxygen consumption (MVO2), related to its hemodynamic determinants, and on myocardial pumping efficiency (eta) at CP. In 10 intact dogs atrial pacing (AP) (90 to 210 beats/min) and ventricular pacing (VP) (70 to 330 beats/min) were investigated in normal and failing hearts. AP and VP were compared at identical rates. MVO2 (4 to 20 ml/min . 100 gr) was measured directly according to the Fick principle. Cardiac efficiency was calculated as the ratio of oxygen equivalent of external cardiac work to MVO2. Rates with maximum CO and a maximal eta occurred only in heart failure. However, maximal CO and eta were obtained at different heart rates (HR). MVO2 was significantly higher (p less than 0.001) under VP as compared to AP at identical rates with a mean increase of 26.5% +/- 6% over AP, although hemodynamics were significantly lower under VP (p less than 0.001). Myocardial pumping efficiency was markedly better under AP with a mean increase of 63% +/- 4.5% over VP even in normal heart. Adjustment of HR at maximal response in CO may become dangerous, particularly under VP, in heart failure. AP, if applicable, may be regarded as the optimal pacing technique due to an optimal relation of improved hemodynamics to MVO2. It may be helpful in correcting an imbalance between oxygen supply and demand in cases of low output syndrome. The pathophysiologic mechanisms and further clinical implications are discussed.

Following single breath inhalations of helium 49 simultaneous inlet-outlet pairs of helium dilution curves were recorded in seven dog experiments from the aortic and coronary sinus blood by use of mass spectrometric technique. After numeric deconvolution of the dilution curves the weighting function of tracer transit times was used for calculation of the mean myocardial blood flow per unit of tissue, which closely correlated with directly measured flow. Secondly, the degree of blood flow heterogeneity was estimated from the first moments of the weighting function of transit times and by compartmental analysis based on an inverse Laplace transform. In the intact heart the results suggest a rather constant dispersion of flows relative to the mean flow F in the order of sigma/F = 0.3. The apparent dispersion of flows is increased by alpha-adrenergic stimulation with pressure and volume load, particularly in a state of beta-blockade, a finding, which may be attributed to variations of intercapillary distances and to a heterogeneity of blood flow per unit of tissue.

The aim of this study was to investigate whether changes in the distribution of pulmonary blood flow and disturbances of the pulmonary microcirculation can be detected by use of inflow-outflow indicator-dilution measurements. In 18 anesthetized (N2O-piritramide) mongrel dogs 221 thermal-indocyanine green dye indicator dilution kinetics were recorded in the pulmonary artery and aorta after central venous indicator injection. The lagged normal density function was used as a model for the pulmonary transport functions for heat and dye. The parameters of the lagged normal density function were computed by a non-linear least squares procedure by iterative convolution. After baseline measurements, in nine dogs, pulmonary edema was induced by central venous application of oleic acid. In nine other dogs, measurements were performed before and after postural changes. Our data show that both the microvascular injury caused by oleic acid edema and the perfusion heterogeneity caused by orthostasis can be detected by the indicator dilution technique since the both relative dispersion and skewness of the transport functions for heat and dye were significantly increased after these interventions.

Our aim was to determine whether large central venous doses of ionic diatrizoate, nonionic iopromide, or nonionic iotrolane produce pulmonary edema or pulmonary congestion in dogs. Eighteen dogs (six per group) anesthetized with piritramide and N2O received three sequential doses (1.5 mL/kg body weight) of one contrast medium in less than 20 seconds. Before the first injection, and again 1, 5, 10, 20, and 30 minutes after each contrast injection, extravascular lung water, pulmonary blood volume, and cardiac output were determined by thermal-dye dilution. Neither extravascular lung water nor pulmonary blood volume increased after any contrast medium. Pulmonary blood volume and cardiac output decreased slightly but not significantly after all contrast media during the course of the study. We conclude that diatrizoate, iopromide, or iotrolane do not produce pulmonary edema or congestion in dogs.

This study was designed to investigate the effects of nicorandil in comparison to isosorbide dinitrate (ISDN) on hemodynamics, on myocardial metabolism and on effectiveness in the preservation of ischemically stressed myocardium. Repeated ischemia (3 min) was produced in anaesthetized open-chest mongrel dogs by proximal, intermittent left anterior descending artery occlusion with subsequent reperfusion. In each experiment 2--3 control occlusions were compared to 2--3 occlusions under nicorandil or ISDN. Application of both nicorandil (0.64 mumol X kg-1 body weight, i.v.) and ISDN (1.27 mumol X kg-1 body weight, i.v.) led to a significant afterload reduction and to a decrease of the coronary vascular resistance. The efficiency of the compounds in the protection of ischemic myocardium was examined by quantification of oxygen-debt and oxygen-repayment in the occlusion and reperfusion periods. Compared to control, premedication with nicorandil led to a significant increase of oxygen-debt, whereas ISDN reduced it significantly. Oxygen-repayment remained unchanged. The influence of the drugs on the metabolism of glucose, lactate and free fatty acids (FFA) was examined under basic conditions, in ischemia and during reperfusion. For all substrates, extraction, extraction ratio and oxygen extraction ratio were calculated. Under basic conditions, glucose metabolism was significantly enhanced in both groups but FFA metabolism was inhibited only by ISDN. In ischemia, FFA metabolism was enhanced by nicorandil and depressed by ISDN.(ABSTRACT TRUNCATED AT 250 WORDS)

The characterization of thromboxane A2 as vasoconstrictor and potent stimulus of platelet aggregation has led to attempts to overcome these effects obviously unfavourable in ischemia. As an attractive approach, we examined potentially protective results of thromboxane synthetase inhibition on canine myocardium stressed by transient ischemia, using as inhibitor the imidazole derivative UK 38.485. On anaesthetized open-chest mongrel-dogs (n = 5) repeated ischemia (3 min) was produced by proximal, intermittent occlusion of the LAD artery. In each experiment 3-4 control occlusions were compared to 3-4 occlusions under therapy. The efficiency of the drug (5 mg/kg body weight, i.v., 30 min before therapy occlusion) was examined (a) by quantification of the energy deficit occurring as the difference between oxygen demand and uptake during occlusion, (b) by the amounts of potassium, inorganic phosphate, and lactate released in the postischemic reperfusion and (c) by changes of the regional myocardial wall function in the central- and peripheral ischemic zone. Compared to control, premedication with UK 38.485 led to a reduced energy deficit (-39.1%; p less than 0.01) combined with a significant decrease in the release of potassium (-15.7%; p less than 0.001), inorganic phosphate (-20.2%; p less than 0.002), and lactate (-20.7%; p less than 0.01). Regional myocardial wall function was improved in the central and peripheral ischemic region as demonstrated by a significantly reduced systolic bulging. The protective effects seem to be mainly due to enhanced flow to ischemic areas.(ABSTRACT TRUNCATED AT 250 WORDS)