Myocardial metabolic monitoring with the microdialysis technique during and after open heart surgery

BACKGROUND

Post-operative ischemia after coronary artery bypass grafting (CABG) is well described but effective intervention requires immediate diagnosis. One possible way of increasing efficacy of peri-operative myocardial monitoring is using the microdialysis technique.

METHODS

In 30 patients undergoing routine CABG, a microdialysis catheter was inserted in the left heart in an area of abnormal ventricular contraction. A second catheter was placed in normal tissue of the right ventricle. Microdialysis measurements were performed at time intervals before, during and 24 h after cardiopulmonary bypass (CPB) and retrospectively compared with standard clinical monitoring and clinical course.

RESULTS

During CPB, both ventricles showed signs of poor tissue oxygenation. Glycerol was significantly higher in the left myocardium (146 +/- 67 vs. 72 +/- 36 micromol/l) and the glucose/lactate ratio (GLR), as a marker of nutritional disorder of the right ventricle (41 +/- 15% vs. 67 +/- 17%, P < 0.05), had significantly better values at this time point. Myocardial lactate concentrations were significantly higher in the dyskinetic segments (2.82 +/- 0.81 vs. 1.5 +/- 0.81 microM). During this period, no abnormal clinical standard monitoring results were observed. Post-operative significantly increased lactate/pyruvate ratios of three patients were clinically associated with peri-operative myocardial infarction (108 +/- 67 vs. 38 +/- 9, P < 0.05). The lactate/pyruvate ratio started rising before any other standard monitoring tools showed abnormal values.

CONCLUSIONS

Peri-operative microdialytic measurements of parameters related to ischemia can be safely performed in a clinical setting, resulting in faster and more reliable detection of ongoing or new ischemia.

[An uncommon cause of recurrent abdominal pain in a 63-year-old obese woman]

HISTORY AND CLINICAL FINDINGS

A 63-year-old woman was admitted because of abdominal pain for 12 months, associated with an increasing abdominal distension. One month before a gastroscopy had revealed mild gastritis. The taking of proton pump inhibitors did not improve her symptoms. There was no relevant neurological or psychiatric past history.

INVESTIGATIONS

Ultrasound and laboratory tests demonstrated a fatty liver and increased serum levels of lipoproteins. Magnetic resonance imaging revealed an increase in subcutaneous and intraperitoneal adipose tissue. Endoscopy did not show any additional significant findings.

DIAGNOSIS AND TREATMENT

The patient had adiposis dolorosa. Initially she was given daily a combination of mexiletine 400 mg and 75 mg Amitriptyline. After a few days the ailment decreased and had disappeared completely after one week. Three months later the dosage was reduced to 100 mg mexiletine and 25 mg Amitriptyline daily. After another two months all medication was discontinued. At follow-up after 12 months the symptoms had not recurred.

CONCLUSION

This case demonstrates that abdominal pain is not always caused by diseases of the visceral hollow organs. It must also be borne in mind that abdominal pain may be associated with adipose tissue, as is the case in adiposis dolorosa. The disease can be successfully treated, as in this case, using a combination of mexiletine and Amitriptyline.

The clinical value of ultrasonic tissue characterization in the management of heart transplant patients

The purpose of this study was to evaluate the rejection process by ultrasonic tissue characterization. Serial 2D echocardiographic images were obtained within 24 h prior to an endomyocardial biopsy. The end-diastolic echoframes were digitized into a computer matrix. A region of interest was placed into the anteroseptal segment of each scan. Image texture was analysed by four major groups of texture analysis (first-order histogram, co-occurrence matrix, run-length statistic, power spectrum). In 23 patients, 408 biopsies were taken after each examination, so that correlation between the ultrasonic tissue measurements and the histological state of the tissue could be determined. When rejection occurred, heterogeneity, brightness and contrast of texture increased. Of 117 texture parameters originally claculated, three parameters (inverse difference moment, run-length non-uniformity, ring sums of power spectrum) that characterized rejection were determined by means of discriminance analysis. Compared with biopsy findings, echocardiographic sensitivity for moderate rejection was 93.3% and specifity 83.6%. Our study indicates that acute rejection is associated with changes in echocardiographic texture. Serial echocardiographic texture analysis can reliably identify heart transplant rejection.

[Intravascular ultrasound-guided diagnosis after transmural anterior ischemia and cardiogenic shock]

Acute coronary syndrome, if complicated by cardiogenic shock, has a high mortality. Urgent coronary angiography is important for decision of therapy. The present paper reports on a patient without angiographically high grade stenosis after thrombolysis. The intravascular ultrasound examination (IVUS) was important for diagnosis of ruptured plaque of the left main stem. Therapy options are discussed.

Detection of Helicobacter pylori specific DNA in human atheromatous coronary arteries and its association to prior myocardial infarction and unstable angina

BACKGROUND

Chronic infections have been proposed to play a role in the aetiology or progression of atherosclerotic plaques. Increased risk of coronary artery disease has been suggested in patients seropositive for Helicobacter pylori.

AIM

To analyse coronary specimens in patients with severe (coronary artery disease) for Helicobacter pylori specific DNA.

PATIENTS AND METHODS

Atherosclerotic plaques were obtained in 46 consecutive patients (9 female, 37 male, mean age 62.7+/-9.17 years) during coronary bypass procedures. Serum was analysed for IgG -/cagA-antibodies specific for Helicobacter pylori. Polymerase chain reaction and sequence analysis were used to identify bacterial DNA. Coronary artery biopsies from 19 autopsies without coronary artery disease were examined as a control group.

RESULTS

Of the 46 coronary artery disease patients, 32 (69.6%) were Helicobacter pylori seropositive. Positive results for Helicobacter pylori DNA showed 18 seropositive and 4 seronegative (with anamnesis of eradication therapy). A total of 22 patients (47.8%) of the coronary artery disease group but none of controls revealed positive DNA. In the coronary artery disease group, a correlation between DNA presence and prior myocardial infarction (p=0.008) and unstable angina (p<0.001) was found.

CONCLUSION

Identification of DNA in atherosclerotic plaques of patients with severe coronary artery disease supports the hypothesis that Helicobacter pylori infection may influence the development of atherosclerosis. Our results may indicate an direct involvement of Helicobacter pylori in the progression and instability of plaques in these patients.

[Cerebral embolism as the first manifestation of left ventricular metastatic bronchial carcinoma]

Commonly the diagnosis of cardiac metastases in extracardiac cancer is difficult because of predominant symptoms of the underlying disease. In the reported case, a cerebral embolization was the first manifestation of a bronchogenic carcinoma with left ventricular metastasis. A 58-year-old male patient was admitted to the hospital with symptoms of an incomplete left-sided hemiparesis that occurred without prodromi. Other clinical abnormalities were not found. The two-dimensional echocardiogram showed a small space-occupying lesion in the left ventricle. Clinical symptoms completely disappeared within 3 days of heparin therapy. In order to prevent repeated embolization (after angiographic exclusion of coronary stenoses), the tumor was excised by cardiac surgery. In the histologic examination, malignant tumor cells were found. As primary origin, a small peripheral bronchogenic carcinoma with (clinically silent) additional metastases to the left adrenal gland and the right pelvic bone was found. The patient died 7 months later because of progressive metastatic cancer disease. Thus (on one hand) the reported case underlines the value of echocardiographic examination in suspected heart manifestation of cancer disease. On the other hand, in patients with heart tumors prior to curative therapy, additional diagnostic procedures (such as CT or MRI) should be performed in order to detect extracardiac tumor manifestations.

Routine minimal invasive vein harvesting reduces postoperative morbidity in cardiac bypass procedures. Clinical report of 1400 patients

OBJECTIVE

Minimal invasive endoscopic vein harvesting has not gained widespread acceptance although potential improvements in wound healing and patient comfort are undebatable. The main objections to routine application have been impaired graft quality and prolonged operation time. The feasibility of introducing the minimal invasive approach to vein harvesting into a high volume cardiac bypass surgery program was to be investigated in 1400 patients.

METHODS

Our preferred technique is based on standard videoscopic equipment for endoscopic surgery. No disposables are used. The subcutaneous tissue above the saphenous vein is tunnelled by exclusively sharp dissection. No shear stresses are applied to the vein graft or its side branches. Side branches are closed by clips or bipolar coagulation. The differences between endoscopic and conventional surgical vein harvesting with regard to operation time, graft quality, wound healing disturbances and postoperative pain were compared in two groups of 300 concurrently operated patients. Subsequently, a further 1100 patients underwent endoscopic vein harvesting, giving a total experience of 1400 endoscopic procedures.

RESULTS

After a learning curve of approximately 100 procedures for an experienced surgeon, harvesting time using minimal invasive techniques was 16 +/- 4 min/graft vs. 10 +/- 2 min for the conventional technique (P < 0.01). Severe wound healing disturbances requiring re-intervention were observed in 0.1% following endoscopic harvesting, moderate wound healing disturbances were observed in 1.7% of patients. By comparison, conventional harvesting led to severe wound healing disturbances in 5% and to moderate disturbances in 8% (P < 0.05). Incidence of peri-operative myocardial infarction as an indirect measure of graft quality was 1.7% with endoscopic vs. 2.3% (n.s.) with conventional technique. Early postoperative mobilisation was faster, pain and need of analgesics were distinctly reduced in patients with endoscopic harvesting. Overall operation time was not significantly prolonged by the described technique.

CONCLUSIONS

Minimal invasive endoscopic vein harvesting can be developed into a routine procedure resulting in a lower incidence of wound complications, less postoperative pain and much superior cosmetic results. Graft quality appears to be comparable to standard saphenectomy. There is, however, a higher demand of surgical training and expertise.

Treatment of humoral rejection after heart transplantation

BACKGROUND

Until a few years ago, the incidence of humoral rejection after heart transplantation was underestimated. These episodes were frequently very aggressive and often fatal, because the maintenance and emergency immunosuppression available at the time only inadequately covered the humoral branch of the immune response. In spite of individual case reports, the effects of blood purification procedures or cyclophosphamide in this situation can only be insufficiently estimated.

METHODS

To evaluate this therapy concept, 20 dog-lymphocyte-antigen-matched dogs underwent heterotopic neck-heart transplantation. Fourteen dogs underwent transplantation after having been previously sensitized through multiple skin transplantations, 6 dogs were not sensitized (control). The animals received an induction with 3x 250 mg prednisolone, as well as triple immunosuppression (cyclosporine, azathioprine, and cortisone). Biopsy (light microscopy, immunofluorescence), intramyocardial voltage, electric myocardial impedance (>200 kHz, <10 kHz), and echocardiographic (left ventricular wall thickness, diastolic relaxation velocity) examinations were performed daily to monitor rejection. Rejection therapy was continued for 3 days according to the following regimen: apheresis, cortisone boluses (CB), and cyclophosphamide in group A1 (n = 4), apheresis and CB without cyclophosphamide in group A2 (n = 4), and CB only in group C (n = 6). The subsequent course under triple immunosuppression was then observed.

RESULTS

In the sensitized animals the onset of severe humoral rejection on the fifth day deteriorated cardiac function down to 75% (70% to 80%) of the initial values. In groups A1 and A2, apheresis resulted in recovery to near-control values (89% to 94%) within two hours, and indeed to complete recovery (97% to 101%) after the second apheresis, that is, within 1 day. In group C recovery was delayed (2 days) and incomplete (84% to 91 %). After therapy was discontinued, rejection-related functional deterioration recurred immediately in group C, and from 2 to 3 days after apheresis, regardless of whether cyclophosphamide therapy was performed (group A1) or not (group A2). In the control group all animals showed a rejection-free posttransplantation course.

CONCLUSIONS

By diluting inflammatory mediators, apheresis leads to a rapid improvement in cardiac function during severe humoral rejection after head transplantation. Neither apheresis nor cyclophosphamide therapy are able to have an immediate positive influence on the activation of the immune cascade and to prevent an ongoing rejection.

Daily noninvasive rejection monitoring improves long-term survival in pediatric heart transplantation

BACKGROUND

Acute rejection episodes and transplant vasculopathy (TVP) account for most of the late deaths after heart transplantation in both adults and children. Accumulating evidence indicates that fatal acute rejection and TVP are related to unrecognized and untreated early and ongoing acute rejection. Day-by-day surveillance of the heart and prompt treatment of any rejection may yield improved long-term survival.

METHODS

In almost all patients having transplantation at our institution (978 patients since 1986), the intramyocardial electrogram (IMEG) was recorded routinely every day through a telemetry pacemaker and transmitted to our center by telephone modem. Earlier studies showed a substantial voltage drop in the IMEG QRS complex is highly indicative of acute rejection, including humoral rejection. In this study, we reviewed the data from 69 pediatric patients up to 16 years old for the incidence of acute rejection, TVP, and long-term outcome. Diagnostic endomyocardial biopsies were performed in only 10 patients, and recent coronary angiograms from 29 children were reviewed.

RESULTS

In 50 children discharged after heart transplantation, IMEG surveillance data for a mean of 2.9 years indicated 72 acute rejection episodes. During follow-up of 1 month to 10.5 years (mean follow-up, 4.4 years), 2 patients died late of causes unrelated to either rejection or TVP. Another patient died of rejection during unrecognized underimmunosuppression nearly 8 years after transplantation and nearly 31/2 years after discontinuing IMEG recordings. Two patients without IMEG recording died of acute rejection or late TVP. In 1 patient, moderate TVP was seen on an angiogram after 41/2 years (incidence, 2.0%; 5-year incidence, 5.6%).

CONCLUSIONS

Daily recording of the IMEG can reliably detect early stages of acute rejection episodes, and immediate rejection treatment seems to keep the incidence of TVP low. The IMEG appears better than all the other rejection monitoring protocols currently in use.

Percutaneous dilatational tracheostomy done early after cardiac surgery--outcome and incidence of mediastinitis

During November 95 to April 97, 45 percutaneous dilatational tracheostomies were performed in a nonselected patient series of 2788 open cardiac surgery cases. Tracheostomy was performed as early as the 2nd postoperative day (median: 6th day), when extubation was not foreseen within the next few days. Duration of intubation was 13 days (mean). We observed 6 complications in 5 patients (13.3%), namely bleeding, misplacement of the tube, subcutaneous emphysema, and superficial infection of the tracheostoma. Mediastinitis and wound infection of the sternal wound did not occur in any single case. There was no death due to tracheostomy. Clinically evident tracheal stenosis and inadequate granulation of the stoma were not observed after extubation. In our opinion, percutaneous dilatational tracheostomy is justifiable, shows good results, and entails minimal risk if done early after cardiac surgery, and it is also superior to standard surgical tracheostomy. Increased incidence of mediastinitis was not seen.

Status of patients presently living 9 to 13 years after orthotopic heart transplantation

BACKGROUND

Heart transplantation has a dramatic impact on both life expectancy and quality of life in patients with terminal heart failure. The aim of the study was to evaluate psychologic, social, occupational, and somatic status of patients living long-term, 9 to 13 years after orthotopic heart transplantation.

PATIENTS AND METHODS

Seventy-seven of 182 patients who received transplants between July 1983 and January 1988 in Hannover (1983-1985; n = 69 patients) and Berlin (1986-1988; n = 113 patients) have survived up to now, 9 to 13 years after transplantation (mean, 10 years 4 months). The patients and their medical records (eg, cardiac catheter studies, echocardiography) were examined to assess their somatic status. Psychologic, social, and occupational status and quality of life data were assessed by combination of self-rating questionnaires (the Short Form Health Survey Questionnaire, Giessener Beschwerdebogen [the Giessen Subjective Complaints List], the Sickness Impact Profile, and the Hospital Anxiety and Depression Scale) and semistructured interviews.

RESULTS

Ninety-one percent of the patients were in New York Heart Association functional class I (70%) or II (21%). The results of the psychologic investigation revealed a definite impact of the side effects of chronic immunosuppression; however, overall, the quality of life rating was within the normal range. Sixty-seven (86%) patients were married, 51 (66%) patients were retired, 17 (22%) worked full-time or part-time, and 9 (12%) were housewife or houseman. Four male patients have fathered five healthy children 1 to 10 years after the transplantation. More than 75% of the patients had normal systolic ventricular function (mean left ventricular ejection fraction, 0.63). Coronary angiograms were normal or with minor wall irregularities in 86% (n = 66 patients), and revealed severe obstructions in 14% (n = 11). Normal function of all valves was found in one-third of the patients, tricuspid valve incompetence was not found or was insignificant in 87% (n = 67 patients) and severe in 8% (n = 10). Six patients had undergone tricuspid valve replacement, invariably for structural valve defects attributable to biopsy injuries. Fifty-eight patients (75%) exhibited various degrees of compensated renal insufficiency, 7 of them were on chronic hemodialysis, and 2 patients have undergone kidney transplantation. Hepatic function was normal in 68% (n = 52) of the patients, and 1 patient has developed liver cirrhosis. Osteoporosis was diagnosed of the discrete form in 7 (9%) and of a significant degree in 24 patients (31%); 38.5% (n = 30) complained of symptoms of polyneuropathy.

CONCLUSIONS

The patients surviving 9 to 13 years after orthotopic heart transplantation are mostly in good physical status, the quality of life is comparable to the general population, and only a few of them have significantly limited in their life style. They do show the substantial chronic side effects of long-term immunosuppression, remaining treatment-dependent for a lifetime.

Mycotic aortic aneurysms after orthotopic heart transplantation: a three-case report and review of the literature

Mycotic aortic aneurysm is a rare yet life-threatening complication after orthotopic heart transplantation. This article reviews three cases of mycotic aortic aneurysm in heart transplant recipients developing in the first year after heart transplantation. Excision of the aneurysm and in situ reconstruction of the ascending aorta were performed with a patch of glutaraldehyde-fixed pericardium or cryopreserved aortic allograft material as a patch or conduit replacement. These cases show that early diagnosis by computed tomographic scanning, surgical treatment, high-dose parenteral antibiotics, and close follow-up are essential for successful treatment.

Survival predictors in patients with a left ventricular ejection fraction of 10-30% receiving a coronary bypass: analysis of preoperative variables

A total of 224 patients with angina pectoris and a left ventricular ejection fraction in the range of 10-30% (mean 24.2%) underwent coronary artery bypass grafting between April 1986 and August 1991. These patients received a mean (s.d.) of 2.9 (0.3) aortocoronary vein grafts. The overall operative mortality rate was 8.9%. The 1-, 2- and 3-year survival rates were 87.7%, 86.7% and 85.2%, respectively. Analysis of operative risk factors showed that patients with an end-diastolic left ventricular pressure > 24 mmHg were significantly more at risk (mortality rate 20.0%, P < 0.05) than those with an end-diastolic left ventricular pressure < or = 24 mmHg (mortality rate 6.2%). Patients with a perioperative cardiac index < 2.5 l min-1m-2 had higher mortality (25.4%) than those with a cardiac index > or = 2.5 l min-1m-2 (mortality 1.9%, P < 0.001). The operative mortality rate of patients with a cardiac index < 2.5 l min-1m-2 and an end-diastolic left ventricular pressure > 24 mmHg was 40.5%. Patients with a left ventricular ejection fraction of 10-20% were not significantly more at risk (P > 0.05) than those with a left ventricular ejection fraction of 21-30%.

Reliable noninvasive rejection diagnosis after heart transplantation in childhood

Rejection diagnosis was exclusively handled with noninvasive techniques in 16 children (mean age, 8.6 +/- 5.7 years; range, 0.9 to 15.2 years) over a total follow-up period of 18.3 patient years. No endomyocardial biopsies were performed. Intramyocardial electrogram recordings and echocardiographic investigations were used as two noninvasive techniques for rejection diagnosis. Daily noninvasive telemetric monitoring of the overnight intramyocardial electrogram was the major diagnostic guideline. The intramyocardial electrogram signal of the sleeping child was transmitted to a bedside receiver by an implanted telemetric pacemaker. The QRS amplitude was automatically analyzed and transferred to the in-hospital computer via a telephone modem connection. Rejection was diagnosed when QRS amplitude fell more than 8% below average baseline levels for 3 successive days, which was the indication for hospital admission. Medical antirejection treatment was instituted only if echocardiography showed impaired early diastolic left ventricular relaxation concomitant with a QRS-amplitude loss. The echocardiographic criterion was a prolongation of the parameter Te (Te is defined as the time span between onset of diastole and peak relaxation velocity of left ventricular wall) by more than 10 milliseconds compared to previous intraindividual values. Survival after a mean follow-up time of 13.7 months (range, 2 to 57 months) is 100%. A total of 22 rejection episodes were treated. During the first 6 postoperative months, the incidence of rejection requiring treatment was 1.4 episodes per patient. In patients at home, distant monitoring detected 13 episodes of a significant QRS-amplitude drop, which led to hospital readmission. In eight children, echocardiography was likewise positive, and rejection treatment was instituted. One child with positive intramyocardial electrography received antirejection treatment because of clinical evidence of rejection, although echocardiography was negative. In three instances, systemic infection was associated with the QRS-voltage loss. In one child a reason for QRS-complex reduction could not be identified. One rejection episode was treated on the grounds of clinical signs and positive echocardiography without a significant QRS-voltage drop. We conclude that distant noninvasive rejection monitoring based on meticulous application of the techniques described is a safe procedure. Daily monitoring of QRS amplitude in patients at home is an excellent safeguard against overlooking significant rejection episodes. This is of special importance in infants and children, in whom routine endomyocardial biopsy cannot be performed. Distant overnight monitoring minimizes psychosocial disturbance during follow-up after heart transplantation.

Intramyocardial electrogram recordings for diagnosis and therapy monitoring of cardiac allograft rejection

The registration of intramyocardial ECG amplitudes (IMEG) is a non-invasive diagnostic method of monitoring cardiac allograft rejection. In order to detect possible sources of error IMEG signals were recorded in heterotopic neck hearts in ten beagle dogs. Immunosuppression was based on cyclosporin A. The rejection process was followed by IMEG registrations as well as by serial myocardial biopsies. Intramyocardial electrogram recordings were made via three unipolar and three bipolar leads obtained from screw-in electrodes in both ventricles and the apex of the allograft. A 10% voltage drop was used as an indicator of rejection. In four dogs, the first rejection episode was treated with methyl-prednisolone and the therapy's success was monitored by IMEG and repeat biopsy. At autopsy the histology of each electrode circumference was correlated with the corresponding IMEG. The average sensitivity of a single lead was not acceptable (unipolar: 28%, bipolar: 47%). When the voltages of different leads were summed up the sensitivity rose to 43% (3 x unipolar), 85% (3 x bipolar) and 100% (all leads). During rejection therapy the IMEG recovered within 24-48 h. We conclude that in moderate allograft rejection (grade 2/3a ISHT classification), the rejection-related changes of intramyocardial ECG voltage amplitude (IMEG) seem to follow a "focal pattern" similar to the histology. Therefore the recording of several, preferably bipolar, electrode configurations appears to enhance adequate diagnostic reliability.

Early diastolic left ventricular function as a marker of acute cardiac rejection: a prospective serial echocardiographic study

Changes in left ventricular early diastolic time intervals are sensitive indicators of incipient left ventricular dysfunction. We tested the hypothesis that acute rejection in cardiac transplant recipients is associated with alteration of early diastolic myocardial function, as expressed by the time interval Te, a parameter derived from digitized M-mode echocardiograms. Te is defined as the time interval between maximal posterior wall contraction and the point of peak posterior wall endocardium retraction velocity, as determined by the nadir of the computed first derivative curve. In transplant patients without rejection (group A, n = 48), Te was prolonged compared to healthy individuals (group C, n = 35) (79.0 +/- 12.5 ms vs 64.0 +/- 7.9 ms; p < 0.0001). During acute rejection (group B, n = 18) transplant patients had significantly longer mean Te values compared to transplant patients without rejection (group A) (97.8 +/- 17.9 ms vs 79.0 +/- 12.5 ms; p < 0.0001). Longitudinal studies in individual patients (group D, n = 18) demonstrated that rejection is associated with prolongation of Te (94.5 +/- 16.0 ms during rejection vs 79.0 +/- 10.3 ms before rejection; p < 0.0002) and that Te returns to individual baseline values in response to treatment (79.2 +/- 9.4 ms after therapy vs 79.0 +/- 10.3 ms before rejection; NS). In a prospective study, Te changes in transplant patients (group E, n = 96) were correlated with myocardial biopsy results. Sixty-one biopsies showed acute rejection, and 115 biopsies were negative.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical heart transplantation without routine endomyocardial biopsy

In a prospective clinical study, routine endomyocardial biopsy (EMB) for early detection of cardiac allograft rejection was replaced by two noninvasive diagnostic techniques. In 32 patients who underwent transplantation during a 6-month period, intramyocardial electrogram (IMEG) amplitude was recorded with the telemetry function of a dual-chamber pacemaker system. An amplitude decrease of more than 8% below the individual range of variability in overnight long-term recordings served as an indicator of rejection. A prolongation of the time interval Te--the time span between maximal posterior wall contraction and peak retraction velocity--of more than 20 msec was used as an additional indicator of rejection-related left ventricular dysfunction. For patient safety, routine EMBs were still performed but remained undisclosed to the transplantation team. The pathologist was asked to intervene in cases of discrepancies between biopsy results and medical decisions, but no such intervention was necessary. Twenty-seven rejection episodes were treated medically, of which 22 were diagnosed noninvasively. In four patients, EMB, ordered because noninvasive parameters remained inconclusive, led to medical treatment. No false negative IMEG results were observed. Retrospective correlation with rejection gave a 100% negative predictive value for IMEG and a 96.9% negative predictive value for echocardiographic diagnosis. We conclude that omission of a schedule of routine biopsies is justified, if the described techniques of IMEG and echocardiography are meticulously applied and indicate normal cardiac function. EMB remains indicated if noninvasive parameters are not conclusive or if false-positive IMEG results, which were observed in the presence of infection or arrhythmias, are suspected. The frequency of EMB can be reduced by 90%, compared to conventional routine biopsy schedules. Diagnostic safety is increased because the additional information gained from IMEG and echocardiography is helpful in the interpretation of EMBs.

Mechanical circulatory support and heart transplantation

Mechanical circulatory support systems are currently in clinical use to keep patients alive with the aim of either cardiac recovery after open heart surgery, myocardial infarction and after heart transplantation with acute graft failure, or as a bridge to transplantation in heart transplant candidates. At the German Heart Institute the "Berlin Heart" mechanical circulatory support system has been used invariably since 1987. Up to 1991 there were 22 patients in the "recovery" group. Four patients could be weaned from the system, but only one patient was discharged from the hospital. In 65 patients mechanical circulatory support systems were implanted as a bridge to transplantation, 39 patients had transplants, and 22 patients left the hospital. Risk factor analysis in the bridging group revealed that previous heart surgery, infective pneumonia, shock-related coagulation disorders, and an age greater than 50 years had an unfavorable influence on patient survival. It is concluded that patients may be kept alive for weeks and months after any kind of cardiogenic shock. Complete cardiac recovery may be achieved in the case of early posttransplant graft failure. Reliable prediction of outcome in the bridge to transplantation group requires further experience.

Coordination of the legs of a slow-walking cat

On the basis of behavioural studies the influences that coordinate the movement of the legs of a slowly walking cat have been investigated. The recording method applied here allows for the measurement of forward and backward movement of the legs which are called swing and stance movements, respectively. Influences between contralateral legs, i.e. both front legs or both hind legs, are stronger than those occurring between ipsilateral legs, i.e. front and hind leg of the same side. Influences which coordinate the front legs seem to be of the same kind as those for the hind legs. These influences are symmetrical, which means that the same type of influence acts from right to left leg and in the reverse direction. Two types of influences are described for contralateral legs: 1. When the influencing leg performs a swing movement, the influenced leg is prevented from starting a swing movement. 2. When the influencing leg performs a stance movement, the probability that the influenced leg starts a swing movement increases as the influencing leg moves backwards during its stance movement. In contrast to contralateral coupling, the ipsilateral influences are symmetric, i.e. a different influence acts from front to hind leg than does in the reverse direction. The front leg is influenced to start a swing when both legs have approached each other to a given value. The hind leg is influenced to start a stance movement after the front leg has begun its swing.