[Pacemaker and implantable defibrillators with telemedical support]. / Schrittmacher und interne Defibrillatoren mit kardiotelemedizinischer Unterstützung.

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.

[Telemedical monitoring of electrocardiograms after cardiac surgery--results from a pilot study among 208 patients]. / Telemedizinisches EKG-Monitoring nach herzchirurgischen Operationen: Ergebnisse einer Pilotstudie mit 208 Patienten.

BACKGROUND: 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. METHODS & RESULTS: 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. CONCLUSION: 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.

[Telemonitoring in chronic heart failure patients. Which diagnostic finding prevents hospital readmission?]. / Telemedizinisches Monitoring bei herzinsuffizienten Patienten Welche. Befundkonstellation verhindert die stationäre Wiedereinweisung?

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.

Minimally invasive, nonendoscopic saphenectomy for coronary bypass surgery.

In 200 consecutive patients who underwent elective and emergency coronary bypass surgery, a minimally invasive, nonendoscopic technique for greater saphenous vein harvesting was used and the clinical results evaluated. The technique is easy, rapid, and routinely applicable in elective and emergency coronary bypass procedures. The cosmetic effect is excellent and the saphenectomy-related morbidity low.

Myocardial protection by pressure- and volume-controlled continuous hypothermic coronary perfusion in combination with Esmolol and nitroglycerine for correction of congenital heart defects in pediatric risk patients.

OBJECTIVE: This study assesses the technical applicability and the clinical value of the continuous coronary perfusion with oxygenated blood as a method for myocardial protection used for congenital heart surgery in pediatric risk patients. METHODS: Thirty non-consecutive pediatric risk patients aged from 1 month to 16 years (mean 3.9 years; 11/30 patients aged <6 months) underwent open heart procedures on the beating heart for simple and complex cardiac malformations using a self designed perfusion system with pressure- and volume-controlled continuous hypothermic coronary perfusion (PVC-CONTHY-CAP) in combination with ultra-short beta1-receptor blockade (Esmolol) and nitroglycerine for myocardial protection. The following procedures were done: VSD patch closure (n = 6), repair of total a-v canal with 'double patch' (n = 4), total repair of tetralogy of Fallot (n = 7), correction of truncus arteriosus communis type IV (n = 1), mitral valve reconstruction (n = 4), total cavo-pulmonary connection (n = 4), and Rastelli procedure (n = 4). RESULTS: The mean cardio-pulmonary bypass time was 131.5 min (range: 44-245 min), the mean coronary perfusion time: 90.1 min (range: 13-202 min). The weaning off extracorporeal circulation was uneventful in all patients, in 21 patients with low-dose and in nine patients with moderate catecholamine support: the mean weaning time was 25 min (range: 7 58 min). The post-operative mean peak creatine kinase (CK-MB) value was 58 U/l, (range: 14-202 U/l). The mean ICU stay in the cardiac surgery unit was 2.9 days, (range: 1-10 days). The mean post-operative mechanical ventilatory support was 2 days (range: 6 h-9 days). Six patients developed thrombocytopenia with values <40 tsd/microl, four patients renal dysfunction, two patients ascites, five patients heart rhythm disturbances, one patient neurological deficits. In three patients (VSD closure: n = 2; age: 1 and 2 months; total a-v-canal: n = 1; age: 3 months) re-do procedures for significant intraventricular shunt had to be done, in one patient implantation of a permanent pacemaker system was necessary. One patient died due to multiple organ failure after uneventful surgery (total cavo-pulmonary connection for single ventricle). CONCLUSIONS: PVC-CONTHY-CAP can be successfully used for repair of simple and complex congenital cardiac malformations. However, in children less than 3 months of age, the transatrial repair of intraventricular defects is technically much more demanding and challenging than under conventional cardioplegic arrest and is possibly accompanied by an increased incidence of residual or recurring intraventricular shunts.

Pulmonary artery growth after systemic-to-pulmonary shunt in children with a univentricular heart and a hypoplastic pulmonary artery bed. Implications for Fontan surgery.

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.

Open heart interventions in premature low- and very-low-birth-weight neonates: risk profile and ethical considerations.

In premature, very-low-birth-weight (VLBW) neonates, complex cardiac malformations can be successfully repaired under conditions of cardiopulmonary bypass. However, due to the immaturity of organ systems, these patients are exposed to a specific risk resulting from noxious effects of extracorporeal circulation, especially on the central nervous system. Two premature neonates with low and very low birth weight of 1160 g and 1650 g, were operated on using cardiopulmonary bypass for severe pulmonary artery stenosis and truncus arteriosus communis type II, respectively. The neonate with pulmonary valve stenosis survived, but at 2-year-follow-up examination motoricity retardation as a result of cerebral immaturity-related changes was evident. The other neonate died suddenly on the fifth postoperative day of a massive intracranial haemorrhage. Due to the fact that the natural history of VLBW children is a priori characterized by a high incidence of major neurological handicaps, open heart surgery may by improving survival chances contribute to an increased incidence of mentally handicapped children.

Myocardial protection by pressure- and volume-controlled continuous hypothermic coronary perfusion (PVC-CONTHY-CAP) in combination with ultra-short beta-blockade and nitroglycerine.

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.

Experience with uni- (LVAD) and biventricular (ECMO) circulatory support in postcardiotomy pediatric patients.

In six pediatric patients with postoperative low-output-syndrome (LOS), uni-(LVAD) and biventricular (ECMO) assist systems with Biomedicus centrifugal pump were used. ECMO was applied in 5 children aged between 3 days and 16 years, one infant with an age of 16 months was implanted with LVAD. One patient from the ECMO-group and the patient with LVAD-support survived. Analysis of vital organ functions during ECMO and LVAD support are presented and characteristics of both support systems for use in pediatric patients with postcardiotomy LOS based on worldwide experience discussed. In conclusion, both, uni- (LVAD) and biventricular circulatory support (ECMO) using Biomedicus centrifugal pump can be safely applied for management of postcardiotomy LOS even in neonates, however, ECMO support in comparison to LVAD is a more aggressive approach associated with a higher complication rate.

Down syndrome as a factor influencing hemodynamic response to pulmonary artery banding.

The hemodynamic response to pulmonary artery banding (PAB) in relation to the preoperative pulmonary/systemic vascular resistance (Rp/Rs) ratio and to the timing of surgery, with special regard to Down syndrome, was investigated in 56 nonconsecutive pediatric patients aged 3 days to 6 months (mean 2.5 months) with simple and complex congenital shunt-related cardiac malformations. Among the non-Down patient group (39 patients; mean age 6.9 weeks) there was a good hemodynamic response in all but three cases, irrespective of the preoperative Rp/Rs ratio; these three poor responders had preoperatively normal or nearly normal Rp/Rs ratios (Rp/Rs < 0.3) and were affected postoperatively by lung complications. In the Down patient group (17 patients; mean age 8.2 weeks) the mean preoperative as well as the mean postoperative Rp/Rs ratio was higher than in the non-Down patient group (preoperative Rp/Rs 0.49 versus 0.32; postoperative Rp/Rs 0.31 versus 0.18). There was a good hemodynamic response in all five patients with Down syndrome who had preoperative normal or nearly normal pulmonary vascular resistance ratios (Rp/Rs < 0.3). Among 12 patients with Down syndrome and preoperative increased resistance ratios (Rp/Rs > 0.3) PAB did not cause a reduction in pulmonary vascular resistance (PVR) in five patients (postoperative Rp/Rs 0.49-1.00), all operated on at more than 6 weeks of age. PAB resulted in effective reduction of postoperative Rp/Rs ratios (range 0.10-0.27) in seven patients, six of them younger and one older than 6 weeks at the time of the banding procedure. In conclusion, patients with Down syndrome and shunt-related cardiac malformations (predominantly total atrioventricular canal cases) in general have higher pre- and postoperative Rp/Rs ratios than non-Down children and also have a higher potential for developing pulmonary vascular obstructive disease despite hemodynamically effective PAB. Especially in children with Down syndrome and pathologically high resistance ratios, PAB, if indicated, should be performed as early as possible.

Changes in plasma cholinesterase activity and mivacurium neuromuscular block in response to normothermic cardiopulmonary bypass.

The effect of reduced plasma cholinesterase (ChE) activity in response to normothermic cardiopulmonary bypass (CPB) on mivacurium neuromuscular block was studied in nine patients anesthetized with propofol/fentanyl. Mivacurium was injected intravenously as an initial bolus of 150 micrograms/kg; repeat doses of 75 micrograms/kg were given when the evoked twitch tension attained 75% of control. With the institution of CPB, the previously normal ChE activity was reduced by 42% and remained low until the end of the procedure. The times of onset (time from the end of injection to maximum neuromuscular block) of the maintenance doses of mivacurium were 26% longer during than before or after CPB (P < 0.05). Their DUR25% (time from end of injection to recovery of neuromuscular transmission to 25% of control) were 13 +/- 3 min (means +/- SD) before, 14 +/- 4 min during, and 16 +/- 4 min (P < 0.05) after CPB. It is concluded, that, although markedly reducing the patient's previously normal ChE activity, normothermic CPB had little effect on the time characteristics of mivacurium neuromuscular block.

[Mechanical circulatory support. 1: Intra-aortic balloon counterpulsation (IABP)]. / Mechanische Kreislaufunterstützung. Teil 1: Intraaortale Ballongegenpulsation (IABP).

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.

[Mechanical circulatory support. 2: Ventricular assist systems]. / Mechanische Kreislaufunterstützung. Teil 2: Ventrikuläre Assistenzsysteme.

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.

Cryopreservation of veins as an alternative to autografts in coronary by-pass grafting.

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.

Mitral valve remodeling using autologous pericardium: an experimental study.

The aim of this study was to assess in vivo the efficacy of a new technique for remodeling the mitral valve. In 6 dogs during cardiopulmonary bypass and cardioplegic cardiac arrest, both mitral valve leaflets were totally separated from the mitral ring and resected subtotally, leaving intact their narrow margins with insertion sites of the chordae tendineae of the first and second order. To mimic pathologic conditions, the chordae tendineae were then altered by placing two shortening sutures for every chordal stem. Based on standardized geometric calculations and using autologous pericardium treated with 0.62% glutaraldehyde solution, the new leaflets were then remodeled intraoperatively and sutured in place, merging them with the subvalvular apparatus and the native mitral ring. After restoration of stable circulatory conditions, valve function was evaluated under rest and defined loading conditions using a 5.0-MHz ultrasound transducer, applied epicardially. We found that intraoperative remodeling of the mitral valve leaflets using autologous pericardium with preservation of the subvalvular apparatus is possible and reproducible, and can be performed even when the subvalvular apparatus is altered morphologically. Functionally, the remodeled valve proved to be satisfactory under conditions of rest and stress. The benefits conferred by autologous tissue, the reproducibility of the surgical technique, the good functionality of the remodeled valve, and the preservation of the subvalvular apparatus could make this technique a useful surgical alternative for extensive mitral valve reconstruction procedures in pediatric and adult patients.

Magnetic activated cell sorting (MACS)--a new immunomagnetic method for megakaryocytic cell isolation: comparison of different separation techniques.

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.

Efficacy of pulmonary artery banding in the prevention of pulmonary vascular obstructive disease.

In 57 nonconsecutive pediatric patients (mean age: 2.6 months) with shunt-related pulmonary hypertension, the efficacy of pulmonary artery banding (PAB) was analysed retrospectively with special reference to the development of pulmonary vascular obstructive disease (PVOD). The patients were grouped in accordance to morphology, hemodynamics and incidence of PVOD. Efficacy of PAB was assessed by pulmonary to systemic pressure, flow and resistance ratios obtained by heart catheterization performed pre- and postoperatively. PAB was very effective in 49 out of 57 patients (= 85.9%), in 8 cases a progression or possible progression of PVOD must be suggested. Only Down syndrome can be considered as a predisposing factor for the development of PVOD. Based on our results we conclude that PAB is a high effective procedure in the prevention of PVOD; however, despite the surgical effectiveness of PAB, PVOD can occur. Strict post-PAB examination of pulmonary flow and resistance parameters is recommended and the definite surgical repair should be performed as early as possible.

[Supra-aortic extracranial revascularization in cerebrovascular disorders with special reference to stage classification]. / Supraaortale extrakranielle Revaskularisation bei zerebralen Durchblutungsstörungen unter besonderer Berücksichtigung der Stadieneinteilung.

The opinions concerning the value of a surgical approach in cerebrovascular insufficiency due to extracranial occlusive arterial disease are still controverse. We analysed a consecutive series of 216 patients after carotid endarterectomy performed in the period of 1980 to 1988. The preoperative symptoms permitted a classification into the clinical groups I to IV according to Vollmar. All operations were done under standard conditions. An intraluminal shunt was used in 194 patients (90%). In 24 patients (11%) a bilateral carotid revascularisation was carried out. The hospital mortality rate in our groups of patients was 5.1%. In order to evaluate the results, Doppler sonographic and clinical examinations with a mean follow-up of 8.1 months (range: 3 to 60 months) were performed. The neurologic examination revealed an unchanged condition in 63 patients (29%). Twelve patients (5.7%) suffered from a progression of the neurologic disorders.

[The energetics and economics of the cardiac pump function]. / Zur Energetik und Okonomie der kardialen Pumpfunktion.

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)