Search PubMed⌕ Search

Biomedical subjects

R Körfer

Publications and source records attributed to R Körfer.

At least 19 recordsLinked to original sources
PubMed2006

Unusual case of an 18-year-old heart transplant recipient with endocardial fibroelastosis.

An 18-year-old female Japanese patient who suffered from heart failure and severe pulmonary hypertension was referred to our clinic. The etiology of her cardiomyopathy was unclear. Inhaled prostacyclin therapy resulted in an improvement of pulmonary arterial pressure and allowed us to avoid lung transplantation. Heart transplantation resulted in a complete remission of her respiratory function. Autopsies of the explanted heart revealed massive endomyocardial fibroelastosis. We concluded that endomyocardial fibroelastosis has to be considered a cause of heart failure in young adults with unclear cardiomyopathy.

Adolescent↗
PubMed2005

Giant coronary arteriovenous fistula. A case report and review of the literature.

Coronary artery fistulas are rare congenital anomalies. Although they constitute the most common form of hemodynamically significant coronary malformation, the incidence is around 0.002% in the general population. We report the successful surgical closure of a very large coronary artery fistula, originating from the left coronary artery and draining into the right atrium with left-to-right shunt of more than 50% and a review of the literature.

Adult↗
PubMed2004

[Mechanical circulatory support: 15 years of experience in the Heart Center North Rhine-Westphalia].

OBJECTIVES: Against the background of an increasing number of patients suffering from severe congestive heart failure, mechanical circulatory support becomes more and more important. The indications for this therapeutic option ranges from bridging to cardiac transplantation, the application of the most recent systems as an alternative to transplantation, as well as in cardiogenic shock following open-heart surgery, acute myocardial infarction of fulminant myocarditis. PATIENTS AND METHODS: Between September 1987 and November 2002, 670 implantations of 11 different mechanical circulatory support systems were performed in 607 patients (125 women, 482 men, age 1 month - 82 years). 255 patients received the device as a bridge to recovery (BTR) of their native organ, 276 patients as a bridge to cardiac transplantation (BTT), 49 patients as an emergency measure in life-threatening cardiogenic shock (bridge-to-bridge, BTB), and 27 patients as an alternative to transplantation (ATT). RESULTS: 38% of the BTR group, 56% of the BTT group, 34% of the BTB group and 27% of the ATT group underwent successful cardiac transplantation or could be discharged from hospital. Infections and thromboembolic events were the most frequent complications but decreased with increasing experience and sophistication of devices. Some systems offer the possibility of discharging patients home while on the device. In our cohort, 90 patients left the hospital on support for a mean duration of 204 days. Readmission rate after 200 days was 50% and was system-related in less than 6%. CONCLUSIONS: In spite of a still considerable morbidity associated with the employment of mechanical circulatory support, the results are encouraging and justify the high economic burden.

Adolescent↗
PubMed2004

[Home monitoring of patients after prosthetic valve replacement-a new method of early detection of valve dysfunction].

Despite enormous progress concerning material and design, patients with artificial heart valves still face a considerable risk of serious complications (e. g. hemorrhage, thromboemboli, redos) which sum up to 5-20% within the first 10 postoperative years depending on type and position of the implanted prosthetic valve. Nowadays technical defects of mechanical valves are negligible and relevant complications are most frequently the consequence of inappropriate oral anticoagulation therapy. To avoid these complications a strict control of both the anticoagulation therapy and the functional integrity of the prosthetic valve is mandatory. Therefore with the aim of risk minimization the patient should be enabled to cooperate by means of methods which are easy to handle in his everyday environment. We present a reliable method for early detection of prosthetic valve dysfunction which can be applied daily with minimal effort by the patient himself.

Administration, Oral↗
PubMed2004

Home monitoring of patients after prosthetic valve surgery -- experimental background and first clinical attempts.

PURPOSE: The purpose of this study was to investigate whether: 1. sound phenomena may be used to detect prosthetic valve dysfunction; 2. clinical and experimental data permit conclusions about alterations in the functional state of mechanical valves; 3. patients can record and pass on signals via Internet. METHODS: 1. We implanted bi-leaflet valves in pigs. By gradually influencing the motion of the tilting discs prosthetic dysfunction could be generated. 2. Thrombosis and lysis of bi-leaflet valves was studied in sheep. This process was documented using echocardiography and acoustically by the Fast Fourier Transformation. 3. Thirty devices were set up and handed out to patients following mechanical valve replacement. All patients regularly sent data to the hospital via Internet, regardless of their location at the time. The data were evaluated by comparing them with the reference file. RESULTS: Animal experiments proved that changes in prosthetic function led to a significant change in sound phenomena. In contrast to echocardiography alterations at an early stage (onset of thrombosis) could be reliably verified. The sensitivity was greater than in echo-control analysis. All patients regularly recorded and passed on their signals. Surveys revealed high acceptance and easy handling of the devices. CONCLUSIONS: Online registration of sound phenomena seems to be suitable for the detection of changes in prosthetic function. This led to the development of the first hand-held device for home monitoring of valve function. Registration of flow, frequency spectrum, and ECG envisaged at the next level opens up potential applications for Internet-based, remote monitoring of cardiac patients.

Animals↗
PubMed2004

Automatic control of the extra-corporal bypass: system analysis, modelling and evaluation of different control modes.

Automatic control of the blood gas parameters during extracorporeal circulation has the potential to improve the quality of this procedure and to relieve the personnel from a time consuming task. This paper describes a model of the underlying system for a standard clinical set-up and pinpoints the major difficulties which are the variations of the process gains and the blood- and gas-flow dependent dead times and time constants. Scheduled PI-controllers both for the arterial oxygen as well as for the carbon dioxide partial pressure were designed. Scheduling was based on the blood flow rate. These controllers were tested in a simulation environment. The control systems remained stable under all tested operating condition, but if the blood flow rate was changed abruptly rather large load errors occurred. The performance was improved markedly by adding a feed-forward control path which directly influences the actuating signals based on the actual blood flow rate and the hemoglobin contents, variables which are measured anyway. The major conclusion of this study is to use such direct feed-forward compensation even if more sophisticated control algorithms are used.

Algorithms↗
PubMed2004

Automatic control of isolated organ perfusion.

If provided with adequate physiological conditions explanted hearts may continue to operate in the regular beating mode. This property offers the opportunity to substitute extensive animal experiments by investigations on the isolated organs. At the same time it enables the development of an alternative method for the transport of donor hearts for transplantation. Experimental setups for both applications are described in this paper. The focus is laid on the optimisation of handling and effectiveness of these setups by means of automatic control. The method for investigating the controlled system ("plant") for blood gas exchange, and especially the determination of the transfer function for the partial pressure of oxygen are described. The plant was triggered with stepwise changes on the gas side at several operating points. A first order lag element with time delay was chosen as approximation of every transfer function. The parameter 'time delay', 'gain of the plant' and 'time constant' were analysed as to the dependency on blood flow rate, gas flow rate and partial pressure of oxygen at the blood outlet of the oxygenator. As a result an equation was found to calculate the time delay from gas flow rate and blood flow rate. Correlation of gain and time constant with parameters of the plant were obtained, too. The data is used for the design of a controller, adapting to the different operating points of the plant.

Algorithms↗
PubMed2004

Aortoplasty with a bovine venous xenograft for pseudoaneurysm after heart transplantation.

The case was a 54-year-old man after orthotopic heart transplantation with infected pseudoaneurysm of the ascending aorta. The operation was performed with hypothermic circulatory arrest. Pseudoaneurysm was excised and aortoplasty was performed with a bovine venous xenograft patch. Six months after the operation, and 2 years after transplantation, the patient is doing well.

Aneurysm, False↗
PubMed2004

Mechanical circulatory support: reality and dreams experience of a single center.

Because of the increasing number of patients waiting for heart transplantation and the decreasing number of donor organs, mechanical circulatory support has become a generally accepted therapeutic option. Several high-tech devices developed in the last 15 years differ in terms of location, kind of support, and driving units. They are suitable for different patients and their therapeutics objectives. Based on 13 years of experience, we developed a specific protocol for selection and management of patients and devices. Six hundred two patients have received mechanical circulatory support (MCS) in our institution since 1987. The indication spectrum includes cardiogenic shock for various reasons: acute myocarditis, right heart failure, acute rejection and postcardiotomy heart failure, alternative to transplantation, and bridge to recovery. Eight different systems are in use at our center. The extracorporeal devices, the Biomedicus centrifugal pump (n = 169) and the Abiomed BVS 5000 (n = 92) are used for short-term support. The Thoratec VAD (n = 179), and Medos HIA-VAD (n = 10) located in paracorporeal position preferably used for midterm support. Novacor LVAS (n= 96), and HeartMate (n = 58) are partially implantable systems used for long-term ventricular assistance in patients who did not require biventricular support. The advantage of the implantable devices is the option of discharging patients under support if they fulfill special criteria before being discharged to home. Eighty-five LVAD patients were discharged home with support, Novacor (n = 52), HeartMate (n = 27), ThoratecTLC-II (n = 8), Lionheart (n = 3) fulfill our criteria for being discharged home while on support. Careful postoperative patient management does not exclude a variety of complications. Bleeding: occurred in 22-35% of patients, right heart failure in 15-26%, neurologic disorder in 7-28%, infection in 7-30%, and liver failure in 11-20%. Complications varied with different devices, and the patients' preoperative conditions. Eighty-five patients fulfilled the criteria of our out of hospital program (OOH) and were discharged from hospital for a mean period of 184 days. Readmission was necessary for complications caused by thromboembolism and infection. This report describes our patient device selection criteria as a bridge to transplant setting.

Clinical Protocols↗
PubMed2003

[Implantation of CardioWest total artificial heart in irreversible acute myocardial infarction shock-new hope for patients with infaust prognosis].

Patients in whom cardiogenic shock develops after acute myocardial infarction have a very high death rate despite early reperfusion therapy. Often hemodynamic stabilization can be achieved only by implantation of a mechanical circulatory support system. When pharmacological therapy and onset of percutaneous assist devices fails in cases representing expansive myocardial impairment without any chance of recovery, the indication for implanting a total artificial heart is given. We report on our first experiences with this extensive and innovative management of irreversible cardiogenic shock patients. In five patients (male, mean age 50 years) the CardioWest total artificial heart was implanted. All patients were in irreversible cardiogenic shock despite maximal dosages of catecholamines, intraaortic balloon pump and/or femorofemoral bypass. In all patients early reperfusion therapy was performed. After implantation of the CardioWest system, rapid recovery of all dysfunctional organ systems occurred in all patients. Four of five patients underwent successful heart transplantation after a mean support time of 156 days. One patient died because of enterocolic necroses caused by embolic event after termination of dicumarol therapy. In summary, first experiences justify this extensive management in these young patients who otherwise would have died within a few hours.

Adult↗
PubMed2003

Recovery of organ dysfunction during bridging to heart transplantation in children and adolescents.

The beneficial effects of ventricular assist devices on organ dysfunction during bridging to heart transplantation have been widely reported in the adult population. In contrast, the use of ventricular assist devices used as bridge-to-transplant in children is limited. To evaluate organ recovery during ventricular support in pediatric transplant candidate, respiratory, renal and hepatic function were reviewed retrospectively. The Thoratec device (stroke volume 65 ml) and the HIA-Medos-system (stroke volume 25/10 ml) were used as bridge-to transplant in 11 children and adolescents who were in low-output-syndrome despite maximal pharmacological support. Prior to implantation five patients were mechanically ventilated, six patients underwent cardiopulmonary resuscitation, eight patients had anuria (one treated by hemofiltration), three patients had liver dysfunction and four patients had signs of severe infection. At the time of implantation one patient was supported by the intraaortic balloon pump and one by the femorofemoral bypass for rapid hemodynamic stabilization. Eight patients were treated using the Thoratec device (one of these by Nova cor on the left side), three by the HIA-Medos system. The support time ranged between seven and 140 days. Seven patients could be extubated within three days. Renal function recovered in all pts. Liver enzymes decreased in all pts without reaching normal values. Bilirubin values also decreased in survivors but increased to 9.3 mg/dL in non-survivors. At least seven patients underwent successful heart transplantation, three patients died because of multiorgan failure after extended transfusion and one patient because of technical failure. In our experience the hemodynamic situation was sufficient in all bridging to transplant candidates. In all patients who underwent successful transplantation, transplantability was associated with rapid organ recovery within seven days after initiating mechanical assistance. Extended blood tranfusions, combined failure of three organs and increasing bilirubin values during support seem to be predictors of poor outcome.

Adolescent↗
PubMed2002

The importance of secondary mitral valve involvement in primary aortic valve endocarditis; the mitral kissing vegetation.

AIMS: Secondary involvement of the mitral valve is well documented in primary aortic valve endocarditis. A poorly considered, but probably important causative mechanism, involving both left-sided valves, is 'mitral kissing vegetation'. This results from large aortic vegetations prolapsing into the left ventricular outflow tract and making contact with the ventricular aspect of the anterior mitral leaflet thus causing secondary infection. METHODS AND RESULTS: In 192 consecutive patients with aortic valve endocarditis, two to 18 (7.6+/-2.6) serial transoesophageal echocardiographic examinations were analysed per patient to demonstrate the development of mitral kissing vegetation on initially competent, morphologically normal mitral leaflets. In 19 patients (9.9%) with aortic valve endocarditis, mitral kissing vegetation was diagnosed within 11.6+/-9.0 (range 1-31) days following primary transoesophageal echocardiography. In all patients with mitral kissing vegetation, vegetations attached to aortic cusps were >6 mm. On hospital admission, patients with aortic valve endocarditis plus mitral kissing vegetation presented more often with a positive sepsis score, embolic events, renal failure and had larger aortic valve vegetations (9.9+/-3.3 vs 5.7+/-2.3 mm). Prognosis of aortic valve endocarditis plus mitral kissing vegetation was unfavourable (P<0.005) when compared to patients with aortic valve endocarditis alone. CONCLUSION: In aortic valve endocarditis early echocardiographic detection of mitral kissing vegetation and timely surgery may preserve the mitral valve apparatus, and favourably influence the long-term prognosis.

Adolescent↗
PubMed2002

Coronary vein leads for cardiac pacing in patients with tricuspid valve replacement.

BACKGROUND: Because after tricuspid valve replacement (TVR) the transvenous implantation of endocardial leads is contraindicated, myocardial screw-in leads were used to ventricular pacing. Recently available coronary vein (CV) leads are stimulating the left ventricle epicardially and can be implanted transvenously, too. METHOD AND RESULTS: We implanted these leads in patients (pts) with TVR (n = 7) or after valve repair (n = 1) without complications. In 7 pts we used bended CV leads with a microporous tip and only in one pt a CV lead with a stimulation via metal ring. The stimulation thresholds (ST) were stable in all pts. CONCLUSIONS: The use of CV leads offers a minimal invasive approach for permanent cardiac stimulation after TVR. Low chronic ST are resulting in an energy saving pacemaker mode. CV leads can be used after previous heart surgery as well as for difficult anatomical situations.

Cardiac Pacing, Artificial↗
PubMed2002

Cardiac remodelling in end stage heart failure: upregulation of matrix metalloproteinase (MMP) irrespective of the underlying disease, and evidence for a direct inhibitory effect of ACE inhibitors on MMP.

OBJECTIVE: To investigate matrix metalloproteinases (MMP-2 and MMP-9) in heart failure caused by ischaemic and idiopathic dilated cardiomyopathy, and the impact of angiotensin converting enzyme (ACE) inhibition on MMP. DESIGN AND MAIN OUTCOME MEASURES: MMP were extracted from myocardium of patients with heart failure (coronary artery disease, n = 13; idiopathic dilated cardiomyopathy (IDCM), n = 16) and from controls (n = 6). The active form of MMP-2 and MMP-9 was measured by enzyme linked immunosorbent assay; activity of MMPs by zymography; mRNA expression of MMPs by reverse transcriptase polymerase chain reaction. RESULTS: Active MMP-9 was significantly increased in coronary artery disease (mean (SD) 1.6 (0.35) ng/ml) and IDCM (2.11 (0.54) ng/ml) in comparison with controls (0.53 (0.15) ng/ml). Increased MMP-2 was only found in IDCM (3.68 (0.41) ng/ml). There were corresponding increases in MMP activity but no upregulation of mRNA expression was found. The ACE inhibitors captopril and ramiprilate inhibited MMP-2 and MMP-9 activity in vitro (inhibitory capacity (IC50), in mmol/l: MMP-2: captopril 2.0 (0.16), ramiprilate 2.1 (0.3); MMP-9: captopril 1.65 (0.18), ramiprilate 2.0 (0.3)). Lisinopril inhibited MMP-9 significantly but did not inhibit MMP-2 in vitro (IC50 MMP-2: 7.4 (0.88); MMP-9: 7.86 (2.23)). Inhibition of MMP activity by ACE inhibitors was blunted by zinc excess. CONCLUSIONS: Upregulation of MMP-9 activity is common in the failing myocardium, independent of the underlying disease. Missing upregulation of transcription suggests that activation of latent forms of MMP is the source of increased MMP activity, rather than increased de novo synthesis. Some ACE inhibitors may influence MMP activity by a direct effect.

Adult↗