[Artificial heart and heart transplantation]. / Kunstherz und Herztransplantation.

The advances in the treatment of many different heart diseases have on the one side led to a significant prolongation of life expectancy but have also contributed to an increase of patients with heart failure. This tendency is supported even more so by the demographic development of our population. The replacement of insufficient organs has always been in the focus of medical research. In the 1960's Shumway and Lower developed the technique of cardiac transplantation and also worked intensively on the treatment and diagnosis of rejection. However, it was Barnard who, in 1967 performed the first human cardiac transplantation. Other centers followed worldwide but the mortality was high and the new therapy was controversially discussed in many journals. By the introduction of cyclosporin as a new immunosuppressive agent in 1978, results improved rapidly and cardiac transplantation became an accepted therapeutic option for patients with end stage heart failure and also for children and newborns with congenital heart defects. Today, with newer immunosuppressive regimens and improved techniques, cardiac transplantation offers excellent results with a long-term survival of nearly 50% of patients after 15 years and among the pediatric population even after 20 years. However, the donor organ shortage as well as the increasing number of elderly patients with end stage heart failure has necessitated work on other alternatives. Neither stem cell transplantation nor xenotransplantation of animal organs are yet an option and there are still some obstacles to be overcome. In contrast, the development of so-called artificial hearts has made significant progress. While the first implants of totally artificial hearts were associated with many comorbidities and patients were seriously debilitated, new devices today offer a reasonable quality of life and long-term survival. Most of these systems are no longer replacing but mainly assisting the heart, which remains in place. These ventricular assist devices have been used as a bridge to transplantation for a long time and are now also offered as a destination therapy for patients who for a variety of reasons are no longer amenable to heart transplantation. Further miniaturization and a decrease of the costs will make these devices a realistic alternative to a sole medical therapy and studies have already proven the superiority in terms of survival as well as rehospitalization rates. However, at present they are still not an alternative to heart transplantation.

Paradoxical embolization of brachiocephalic and pulmonary arteries in a case of persistent foramen ovale: a case report.

Paradoxical embolism is the result of systemic arterial embolism and pulmonary embolism. It indicates the presence of an intracardial defect in the area of the atrial or ventricular septum. The most frequent cause of an intracardiac defect associated with paradoxical embolism is a patent foramen ovale (PFO). In the case presented here, the symptoms, diagnostics and surgical therapy are discussed.

Inhibition of carotis venous bypass graft disease by intraoperative nucleic acid-based therapy in rabbits.

BACKGROUND: Bypass graft stenosis after venous revascularisation procedures is characterised by massive neointimal and vascular smooth muscle cell proliferation triggered via endothelin-1 synthesis in the vessel wall. Decoy oligodesoxynucleotides (ODN) against the transcription factor activator protein-1 (AP-1) inhibits pre-pro-endothelin-1 expression. METHODS: In 20 rabbits, an end-to-side jugular vein bypass to the carotid artery was performed: (group A) 8 grafts were treated with consensus AP-1 decoy ODN, (group B) 8 with mutated control ODN and (group C) 4 received no treatment. Explantation, histomorphometric and immunohistochemical evaluation was performed after 28 days. RESULTS: Median intimal thickness of groups: (A) 28.3 microm, (B) 48.4 microm, (C) 71.1 microm. The decoy ODN-treated group showed a significant reduction of neointima formation ( P = 0.029) and a downregulation of the endothelin receptor. CONCLUSIONS: In this model, neointima formation was reduced by local transfection with consensus decoy ODN against AP-1. Endothelin A and B receptor expression is downregulated. Molecular target nucleic acid-based therapies seem to be a future means of overcoming neointima proliferation in pressure-induced venous graft failure. Intraoperative local application makes it easy to use in routine revascularisation procedures.

High-field MR angiography on an in vitro stenosis model determination of the spatial resolution on 1.5 and 3T in correlation to flow velocity and contrast medium concentration.

Since the first description of coronary magnetic angiography (MRA) in the early of 1990, this method seems to be shaped us a promising noninvasive modality to view the coronary arteries. Since several years dedicated high-field MR systems up to 4T are available for human use. The aim of the study was the evaluation of an in vitro vessel model with defined stenoses on 1.5T and 3T. For imaging at 3T, we used a 3d gradient-echo-sequence (fast SPGR). Furthermore, we examined the influence of the flow velocity and the contrast medium concentration on the spatial resolution. The accurate detection of in vitro stenoses was possible in segments up to 0.6 mm at 3T, the best results were obtained at a flow velocity of 40 ml/min and a contrast medium concentration of 0.2 mmol/l. The influence of the contrast medium concentration was statistically not significant. These results show that the spatial resolution can be increased by the use of a high-field MR scanner. Further in vivo studies are necessary to eliminate the method's limitation in visualizing small distal vessel segments.

Repair of recurrent coarctation using an ascending aortic autograft.

Results of aortic arch repair for interrupted aortic arch or aortic coarctation have considerably improved. However, re-stenosis or aneurysm formation is a common complication requiring complex re-interventions or even extra-anatomic bypass grafting. In two patients with recurrent coarctation, the use of cardiopulmonary bypass was mandatory, in one due to the concomitant repair of the intra-cardiac defect, in the other due to the small aortic arch, the long segment aortic coarctation and the small diameter of the supra-aortic vessels. In both patients a segment of the ascending aorta was interposed between the distal aortic arch and the proximal descending aorta with uneventful postoperative courses and freedom from pathological findings at 1 year and 6 months follow-up. In patients undergoing complex congenital heart surgery involving the ascending aorta, a segment of the autologous ascending aorta may be used to repair recurrent isthmic stenosis, avoiding the use of any foreign material.

Giant left atrial mass in an asymptomatic patient.

A large atrial myxoma, attached in an atypical location, was identified in the left atrium of a 70 year old patient. Although the tumour occupied a large part of the left atrium the patient remained in sinus rhythm and displayed no symptoms.

Efficacy of ion-selective probes in early epicardial in vivo detection of myocardial ischemia.

Myocardial hypoxia is accompanied by increased epicardial potassium activity. In this experimental study in rabbits (n = 13), with ion-selective probes, we correlated our findings with an exact evaluation of myocardial oxygen tension, hemodynamic data and arterial and venous blood gas analysis. The epicardial potassium activity had good correlation with these parameters (pm = -0.95, pco = -0.93 and pa = -0.72, pv = -0.96, respectively). Therefore, the clinical use of these electrodes can be recommended for continuous monitoring in intensive care units.

INR self-management permits lower anticoagulation levels after mechanical heart valve replacement.

BACKGROUND: The Early Self Controlled Anticoagulation Trial (ESCAT I) showed that anticoagulation self-management after mechanical heart valve replacement decreased complication rates by maintaining INR levels closer to the target range than International Normalized Ratio (INR) home doctor management. The therapeutic range for the INR in that study was between 2.5 and 4.5 for all positions of prosthetic valves. ESCAT II should find out whether lowering the target range for INR self-management would further reduce complication rates. METHODS: ESCAT II is a prospective controlled randomized (valves: St. Jude Medical Standard or Medtronic Hall, treatment: conventional/low-dose) multicenter study with 3,300 patients. We present interim results of 1,818 patients. 908 were categorized as having a low-dose target range, which was INR 1.8 to 2.8 for prostheses in aortic position and 2.5 to 3.5 for prostheses in mitral position or in combined valve replacement. The control group (conventional group) with 910 patients aimed at an INR of 2.5 to 4.5 for all valve positions. RESULTS: In the conventional group, 74% of INR values measured were within the therapeutic range. In the low-dose group, 72% of the values were within that range. The linearized thromboembolism rate (% per patient year) was 0.21% for both groups. The bleeding complication rate was 0.56% in the low-dose regimen group versus 0.91% in the conventional group. CONCLUSIONS: Early onset INR self-management under oral anticoagulation after mechanical heart valve replacement enables patients to keep within a lower and smaller INR target range. The reduced anticoagulation level resulted in fewer grade III bleeding complications without increasing thromboembolic event rates.

[Detection of myocardial ischemia by epicardial detection of potassium ion activity]. / Myokardialer Ischämienachweis durch epikardiale Detektion von Kaliumionenaktivitäten.

Early detection of myocardial ischaemia is a central problem in cardiological and cardiosurgical intensive care. A new approach is the use of ion-selective electrodes implanted directly on the myocardium, enabling detection of increased potassium activity as an indication of general hypoxia. After a comprehensive study of the electrode parameters, an animal experiment was carried out, in which it was found that respiration-induced hypoxia resulted in an increase in epicardial potassium activity (p < 0.01). Blood gas analysis performed simultaneously revealed reduced arterial pO2, but no acidosis. Haemodynamic data evidenced hypoxic depression of circulatory parameters. Histological examinations of the myocardium beneath the electrodes revealed typical lymphocytic infiltration. Electron microscopy demonstrated crystolysis in the mitochondria as an early sign of hypoxia, thus confirming the sensitivity of these electrodes. This underscores the potential of ion-selective electrodes for the detection of myocardial ischaemia, and they should now be investigated in the clinical setting.

Serum S-100beta protein release in coronary artery bypass grafting: laminar versus pulsatile flow.

BACKGROUND: Cerebral injury after Cardiopulmonary bypass (CPB) is still a serious and unpredictable complication. The S-100beta serum marker has been suggested as potentially useful in the detection of cerebral injury during and after CPB. Direct comparisons of whether laminar or pulsatile pump flow in CABG leads to higher S-100beta values and which type might be more neuroprotective have not been made so far. METHODS: All 21 patients of the study were undergoing CABG for the first time and had no history of cerebral disease in whatever form. They were divided into two groups: laminar (n = 10) versus pulsatile (n = 11) pump flow. In all cases, a Stöckert roller pump (Fa. Stöckert, Munich, Germany) with a laminar and pulsatile running mode was used for cardiopulmonary bypass. Serum S-100beta levels were detected using a monoclonal immunoradiometric assay (Sangtec Medical AB, Bromma, Sweden). In total, 5 different samples were drawn per patient, starting before intubation and ending 36 hours after surgery. RESULTS: S-100beta peak values were found at skin closure. Median levels were lower in the pulsatile group. Due to the small study group and wide range, results are non-significant. CONCLUSION: The results indicate that pulsatile flow might have a more neuroprotective effect than laminar flow as S-100beta values were lower.

[Difficulties in noninvasive cardiac stroke volume determination in "small" blood circulation systems]. / Probleme der nichtinvasiven Herzzeitvolumenbestimmung in "kleinen" Blutkreisläufen.

Pulsewave velocity analysis is an option for the noninvasive determination of cardiac output and the evaluation of additional haemodynamic parameters. An algorithm we developed ourselves has been established as a method for the measurement of cardiac output in rabbits. The effectiveness of this program was investigated by monitoring controlled hypoxia-induced alterations in the circulatory system. Calculated values were compared with direct measurements of cardiac output with a Doppler flow probe placed in the ascending aorta. Within the physiological framework of blood gas analysis, a good correlation was found between the two methods. In the case of hypoxia-induced depression, however, the two methods showed diverging results, presumably due to arrhythmia-induced wave reflections within the arterial vascular tree. This makes an extension of the algorithm necessary to take account for these case.

Improved myocardial preservation with short hyperthermia prior to cold cardioplegic ischemia in immature rabbit hearts.

OBJECTIVE: Recent observations have been shown that the induction and accumulation of heat shock proteins (HSPs) by short exposure to nonlethal whole-body hyperthermia with normothermic recovery are closely associated with transient resistance to subsequent ischemia-reperfusion challanges. Here, this study was performed to investigate whether a shortly heat shock pretreatment affects the left ventricular (LV) function after cold cardioplegic ischemia in reperfused neonatal rabbit hearts. METHODS: Hearts from neonatal New Zealand White rabbits were isolated perfused (working heart preparation) and exposed to 2 h of cold cardioplegic ischemia followed by reperfusion for 60 min. To induce the heat shock response neonatal rabbits (n=5, HT-group) were subjected to whole-body hyperthermia at 42.0-42.5 degrees C for 15 min, followed by a normothermic recovery period of 60 min, before harvesting and the onset of global hypothermic cardioplegic arrest. Another set of hearts (n=5, control group) without a heat treatment underwent a similar perfusion and ischemia protocol served as control. The postischemic recovery was assessed by measuring several parameters of LV function. LV biopsies from all control and heat treated animals were taken before ischemia and at the end of reperfusion to examine myocardial HSP levels by Western blot analysis. RESULTS: At 60 min of reperfusion the HT-group showed significant better recovery of ventricular function such as LV developed pressure (DP) (74.6+/-10 vs. 52.1+/-8.5%, P<0.05), LV positive dP/dt (910+/-170 vs. 530+/-58 mmHg/s, P<0.01) and LV end-diastolic pressure (LVEDP) (8+/-2 vs. 18.4+/-5 mmHg, P<0.05) than control. Myocardial oxygen consumption (MVO(2)) was significantly higher in the HT-group compared with control (0.054+/-0.006 vs. 0.041+/-0.002 ml/g per min, P<0.05). Significant postreperfusion lower level in lactate production was observed in the HT-group (0.83+/-0.11 vs. 1.67+/-0.8 mmol/l, P<0.05). Also, the recovery of hemodynamic parameters such as aortic flow, coronary flow and cardiac output was significantly superior (P<0.05) in the HT-group. Furthermore, high expression of HSP72(+)/73(+) were detected in the myocardial tissue samples of heat-treated rabbits by immunoblotting, appearing even at 60 min of normothermic recovery after heat stress. CONCLUSIONS: These data in the immature rabbit heart indicate that previous shortly heat treatment with high level expression of heat shock proteins (HSP72(+)/73(+)) before hypothermic cardioplegic ischemia provides transient tolerance against myocardial injury and could be an improvement for the postischemic functional recovery of neonatal hearts.

[Measuring stroke volume of the ascending aorta with an extravascular Doppler ultrasound probe in comparison with aortic thermodilution]. / Messung des Herzzeitvolumens an der Aorta ascendens mit extravaskulärer Doppler-Ultraschallsonde im Vergleich zur aortalen Thermodilution.

Currently, no reliable minimally invasive method of measuring cardiac output continuously in neonates and children undergoing cardiac surgery is available. An extravascular Doppler probe was used to measure cardiac output in 15 New Zealand White rabbits (average weight 3.5 kg, range 2.5-4.5 kg). The results obtained were compared with cardiac outputs determined using the aortic thermodilution principle. The mean cardiac outputs measured with the extravascular Doppler probe was 0.37 +/- 0.01 l/min as compared with 0.39 +/- 0.01 l/min with aortic thermodilution. Regression analysis revealed a close correlation (r = 0.973) between the two techniques. The extravascular Doppler techniques is an option for continuous and reliable cardiac output measurement in small animals used in surgical experiments (open chest models) and in neonates or children during surgical repair of complicated congenital heart conditions.

Mycotic pseudoaneurysm of the aorta in children.

Mycotic pseudoaneurysm of the aorta is a rare disease in childhood. We report on two cases which were diagnosed in an unselected general pediatric population within an 8-month period. The first case was a 16-month-old toddler with a normal cardiac history who presented with purulent pericarditis due to group A streptococcus and subsequent pseudoaneurysm formation of the ascending aorta while convalescing from varicella infection. The second case was a 14-year-old girl with a previously undiagnosed coarctation of the aorta who developed a Staphylococcus aureus aortitis in the dilated poststenotic segment with pseudoaneurysm formation and infiltration into the adjacent lung tissue. In both cases parenteral antibiotic therapy was administered over 10 and 4 days, respectively, followed by emergency surgery consisting of aneurysmectomy, coarctectomy (case 2), and in situ homograft implantation. Recovery was uneventful. In both cases early institution of a femorofemoral cardiopulmonary bypass prevented a fatal outcome despite intraoperative rupture of the pseudoaneurysm.

Linear lesion formation by ND:YAG laser versus radiofrequency energy in porcine atria.

The efficacy of RF energy versus the neodymium:yittrium aluminum-garnet laser to create linear lesions was compared in fresh ex vivo swine hearts. A total of 598 lesions were created in four locations: ostium of the pulmonary veins, trabeculated lateral left atrium, smooth posterior part of the right atrium, and the isthmus between the inferior vena cava and tricuspid valve. A 400-micron bare quartz fiber with CO2 cooling (distance to the tissue 5, 10, and 15 mm) and an RF ablation catheter (4-mm tip) were mechanically dragged over the tissue at speeds 0.5, 1.0, and 1.5 mm/s. A continuous and transmural ablation line was recorded as successful. A 100% success rate was achieved at the pulmonary veins and the isthmus at some settings of energy delivery by the laser and RF. In the thick posterior right atrium, RF resulted in transmural lesions only when associated with carbonization, while the laser produced successful ablation lines in 100% of the attempts. In the left atrium, because of the presence of prominent trabeculations, RF was unsuccessful at all settings of energy delivery. In contrast, deep photocoagulation by laser resulted in successful ablations in the left atrium in 100% of attempts. Lesion formation was faster by laser ablation and mean lesion width was at least 25% smaller with the laser than with RF. In conclusion, the formation of linear lesions at the isthmus and at the pulmonary veins was successful with the laser and RF. In the trabeculated left atrium and the thick posterior right atrium, only laser ablation was successful.

Indications, results, and pitfalls in the surgery of constrictive pericarditis.

Constrictive pericarditis is a rare disease with an often unclear etiology. There may be a long delay between the onset of the underlying disease and the onset of clinical symptoms, which are fatigue, abdominal swelling, peripheral edema and breathlessness. However, if clinically apparent, these symptoms may progress rapidly and severely disable the affected patient. Diagnosis is achieved by the clinical presentation, echocardiography and/or MRI and right heart catheterization. The standard therapy is an extended pericardiectomy to restore an unlimited inflow and outflow as well as an unrestricted diastolic function of both ventricles. The risks of this procedure are related to dense adhesions between the 2 pericardial layers and severe calcifications especially of the epicardium. Incomplete removal results in persistent diastolic restriction while lacerations of the underlying myocardium may lead to diffuse and extensive bleeding and finally to myocardial dysfunction. Also, the postoperative course may be complicated by persistent low output syndrome or acute ventricular dilatation. However, early surgical intervention in the hands of experienced surgeons offers the best prognosis.