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Biomedical subjects

Thomas Busch

Publications and source records attributed to Thomas Busch.

7 recordsLinked to original sources
PubMed2005

Delay-induced excitability.

We analyze the stochastic dynamics of a bistable system under the influence of time-delayed feedback. Assuming an asymmetric potential, we show the existence of a regime in which the system dynamics displays excitability by calculating the relevant residence time distributions and power spectra. Experimentally we then observe this behavior in the polarization dynamics of a vertical cavity surface emitting laser with optoelectronic feedback. Extending these observations to two-dimensional systems with diffusive coupling, we finally show numerically that delay-induced excitability can lead to the appearance of propagating wave fronts and spirals.

Feedback↗
PubMed2005

Molecular magnetic resonance imaging of atrial clots in a swine model.

BACKGROUND: The detection and differentiation of intracardiac masses is still challenging and may include neoplasms and thrombi. The aim of this study was the investigation of a targeted, fibrin-specific contrast agent (EP-2104R) for molecular targeted magnetic resonance imaging (MRI) of left atrial clots. METHODS AND RESULTS: Chronic human thrombi were surgically implanted in the left atrial appendage of 5 swine. Molecular MRI was performed with a navigator-gated, free-breathing, cardiac-triggered 3D inversion-recovery, black-blood, gradient-echo sequence before and after systemic administration of 4 micromol/kg EP-2104R. MR images were analyzed by 2 investigators, and the contrast-to-noise ratio was calculated. Location of clots was confirmed by autopsy, and the gadolinium concentration in the clots was assessed. Before contrast agent administration, thrombi were not visible on black-blood MR images. After contrast administration, all atrial clots (n=5) were selectively visualized as white spots with a high contrast-to-noise ratio (clot/blood, 29.7+/-8.0). The gadolinium concentration in the clots averaged 74+/-45 micromol/L. CONCLUSIONS: The fibrin-specific MR contrast agent EP-2104R allows for selective and high-contrast visualization of left atrial clots by means of molecular targeted MRI.

Animals↗
PubMed2005

Congenital coronary artery fistulas in adults: surgical treatment and outcome.

BACKGROUND: Congenital coronary artery fistulas, a subgroup of anomalies of the coronary arteries, are an extremely rare cardiac defect. Most patients are asymptomatic, and if symptoms are presented, they depend on the underlying anatomy. Knowledge of those fistulas is important for prognosis and management. METHODS: Thirteen adult patients with congenital coronary fistulas (8 male, 5 female) were operated in our department during the last decade (1990-1999). Mean age was 61.5+/-10.8 years. Diagnosis was made by coronary angiography, and 15 congenital coronary artery fistulas were found. RESULTS: All patients were symptomatic with clinical symptoms depending on the associated cardiac disorder. Coronary artery fistulas originated from the proximal left descending artery (n=10), left main stem (n=3), circumflex artery (n=1), right coronary artery (n=1), and drained into the main pulmonary artery (n=14) and left ventricle (n=1). Nine fistulas (60%) were interrupted on the outside of the heart, and six fistulas (40%) were closed through the opened pulmonary artery. There was no surgical death and no fistula-related complication. CONCLUSIONS: Surgical closure of congenital coronary artery fistulas in adults can be performed with a very low risk, and closure is recommended to prevent complications.

Adult↗
PubMed2005

Intraoperative hemofiltration in adults: prevention of hypercirculatory syndrome?

Hypercirculatory syndrome (HCS) after cardiac surgery may be a sequela of extracorporeal circulation due to hemodilution and release of inflammatory mediators. The aim of this study was to investigate the influence of intraoperative hemofiltration (HF) on the incidence of HCS. A prospective cohort study of 80 patients scheduled for elective coronary bypass was performed. The patients were randomized to two groups: in the conventional (CONV) group 40 patients were treated conventionally and in the HF group 40 patients underwent intraoperative HF. There was no perioperative mortality. The incidence of HCS was comparable in both groups (32% in CONV group versus 40% in HF group; n.s.). Mean cardiac output was higher and systemic vascular resistance lower in CONV group patients than in HF group patients, however these differences did not reach statistical significance. According to this data intraoperative HF does not prevent postoperative HCS induced by cardiopulmonary bypass. Further studies are required to identify the etiology of HCS, and to prevent it occurring after open-heart surgery.

Aged↗
PubMed2005

Surgery for non-small cell carcinoma in geriatric patients: 15-year experience.

The purpose of this study was to determine the clinical patterns, short- and long-term survival in elderly patients after surgery for non-small cell lung carcinoma. The 273 patients aged over 70 years who underwent curative resection from 1986 to 2001 were retrospectively assessed. Mean age was 73.2+/-3.1 years, (11% were>80 years). The mean follow-up was 31 months. Standard procedures were used: 151 lobectomies, 49 bilateral lobectomies, 42 pneumonectomies, 9 sleeve resections, and 22 wedge resections. The 30-day mortality was 5.4%. Multivariate analysis showed that extended procedures, male sex, and age were predictors of mortality. Overall survival rates at 5, 10, and 15 years were 35.6%, 10.5%, and 2.5%, respectively. Advanced disease stage, low forced expiratory volume in 1 second, and previous cardiac disease were independent predictors that adversely influenced survival. Geriatric patients with non-small cell lung carcinoma can undergo resection safely with acceptable long-term survival. Lobectomy is the procedure of choice, extended resections should only be carried out in highly selected patients. Careful attention to preoperative clinical staging is important as the elderly beyond the early stage of disease fare poorly. Surgery is justified for the treatment of stage I-II lung cancer.

Adenocarcinoma↗
PubMed2002

Methylene blue administration in severe systemic inflammatory response syndrome (SIRS) after thoracic surgery.

A 66-year-old male patient developed significant pleural effusion on the right side six years after coronary bypass grafting and mitral valve replacement. After pleurocentesis, hemo-pneumothorax developed and finally resulted in complete atelectasis of the right lung. Three weeks later, the patient was transferred to our department, and underwent a right lateral thoracotomy. The hematoma was removed and a complete decortication was performed. Four hours postoperatively the patient developed severe SIRS with beginning multiorgan failure. Even extremely high doses of norepinephrine could not raise the systemic vascular resistance. Single intravenous administration of methylene blue lead to significant and permanent improvement of the hemodynamic status.

Aged↗