Changes of the local oxygen content and ordering at twin boundaries of high-Tc YBa2Cu3O7-x superconductors.
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Journal Article↗
Biomedical subjects
T Walther
Publications and source records attributed to T Walther.
The stentless Toronto SPV bioprosthesis for aortic valve replacement.
The Toronto SPV bioprosthesis for aortic valve replacement has been prospectively evaluated in 100 patients, since March 1993. Intraoperative transoesophageal and postoperative transthoracic echocardiography were used to assess valve function. Follow-up was complete in 74 patients at 6 months and in 38 patients at 1 year. The average valve size implanted was 26.5 mm. Some 37 patients had additional coronary artery bypass grafting surgery. The hospital mortality rate was 4%. Non-structural valve dysfunction occurred in one patient and late endocarditis in another patient required operation. There were no other valve complications. None of the patients developed clinically relevant aortic valve incompetence during follow-up and there was a significant decrease in pressure gradients, increase in valve orifice areas and decrease in left ventricular hypertrophy.
Aged↗
Surgical treatment of abdominal aortic aneurysms of octogenarians.
The purpose of this study was to determine whether elective abdominal aortic aneurysmectomy in octogenarians is justified or may even be advisable. Between January 1986 and August 1993, 30 octogenarians of mean age 83.1 (range 80-93) years underwent abdominal aortic aneurysmectomy. Patients were divided into two groups: group 1 (n = 9) underwent elective surgical repair; group 2 (n = 21) underwent emergency procedure. In 28 patients location of the abdominal aortic aneurysm was infrarenal; two patients presented with a juxtarenal aneurysm. The average aneurysm diameter was similar in both groups (group 1, 68.8 mm; group 2, 83.5 mm, P = n.s.). In group 2, two patients had free peritoneal rupture, one presented with rupture into the duodenum and one with penetration into the vena cava. Rupture was confined to the retroperitoneum in another 15 patients. Two patients had an expanding aneurysm. Hospital mortality rate was zero in group 1 and 42.8% in group 2 (P = 0.011). Most early deaths were related to cardiac disease. The overall complication rate was 22% in group 1 and 62% in group 2. Mean intensive care unit time was 1.8 (range 1-3) days in group 1 and 3.6 (range 1-8) days in group 2 (P = 0.47). The 5-year survival rate was 67% in the electively managed group and 34% in the emergency group.
Aged↗
Assessment of metabolic liver function and hepatic blood flow during cardiopulmonary bypass.
A modified monoethylglycinexylidide (MEGX) test was performed in 14 patients undergoing myocardial revascularization to evaluate liver function during cardiopulmonary bypass (CPB). MEGX is the principal metabolite of lidocaine. Different studies have shown a decrease in MEGX formation in patients with impaired liver function. Following a low-dose bolus application of 0.3 mg/kgBW lidocaine MEGX concentrations were measured in five-minute intervals for half an hour. This was done once before and once during CPB. Arterial and hepatic vein blood samples were obtained in order to avoid the effects of hemodilution by CPB priming. Hepatic blood was calculated using the indocyanine green (ICG) infusion extraction technique. MEGX formation during CPB decreased. After the 10 and 15 minutes measurement points the mean arterio-hepatic venous concentrations were 61 +/- 7.2 micrograms/L and 63 +/- 7.3 micrograms/L respectively in comparison to pre-CPB values of 36 +/- 5.8 micrograms/L and 42 +/- 5.1 micrograms/L. Hepatic blood flow increased insignificantly from a mean of 835 +/- 54 ml/min prior to CPB to 913 +/- 83 ml/min during CPB. As a result the MEGX clearance calculated 15 minutes after administration of lidocaine bolus application did not differ significantly before (51.2 +/- 6.4 micrograms/min) and during CPB (40.2 +/- 5.7 micrograms/min). In conclusion, a decrease in MEGX formation was found during CPB. However, due to increased hepatic blood flow there was no significant change in MEGX clearance before and during CPB.
Adult↗
Resection of a thrombus floating in the aortic arch.
A 42-year-old patient had resection of two thrombi floating in the aorta under circulatory arrest. Atherosclerotic plaques in the isthmus and in the descending thoracic aorta predisposed the patient to thrombus formation. Intraoperative transesophageal echocardiography was used to guide the surgical approach.
Adult↗
Echocardiographic monitoring of minimally invasive mitral valve surgery using an endoaortic clamp.
BACKGROUND AND AIMS OF THE STUDY: Twenty-four patients underwent minimally invasive mitral valve repair (n = 16) or mitral valve replacement (n = 8) using the Port-Access system. Intraoperative transesophageal echocardiography (TEE) was used in these patients to: (i) reassess valve pathology preoperatively; (ii) guide and continuously assess placement and position of the aortic endoclamp; (iii) measure aortic root diameters, aortic distensibility and aortic wall appearance prior to and after aortic endoclamping; (iv) evaluate the de-airing procedure; (v) evaluate the results of mitral valve repair; and (vi) guide weaning from cardiopulmonary bypass (CPB). METHODS AND RESULTS: Placement and positioning of the endoclamp was guided effectively in all but one patient who had acute retrograde aortic dissection with the onset of femoro-femoral bypass. The mean position of the tip of the endoclamp was 2.8 +/- 0.5 cm from the aortic valve annulus. The position was stable in all but five patients in whom repositioning and additional clamp volume were required. There was only a poor relationship between balloon volume and sinotubular junction diameter. The dynamic movement of the aorta was well preserved after clamping and the elasticity module did not change significantly (1.6 +/- 0.71 vs. 1.5 +/- 0.75 dynes x 10(6)/cm2). No intimal tears or wall edema was observed after clamp release. De-airing was incomplete in five patients, two of whom had transient ST-elevations with regional wall motion abnormalities. Weaning of CPB was therefore postponed until the ECG had normalized. All mitral valve repairs but one were successful (equal to or less than grade I residual mitral insufficiency). One patient with persistent grade II mitral insufficiency underwent valve replacement using the same approach. CONCLUSIONS: TEE can effectively guide minimally invasive mitral valve surgery using the Port-Access system. Placement and positioning of the endoclamp and its effects on the aortic wall can be evaluated. De-airing, weaning from CPB and the results of the procedure were effectively monitored using TEE.
Aorta↗
Stentless bioprostheses for the small aortic root.
BACKGROUND AND AIMS OF THE STUDY: Despite a variety of different artificial heart valves no ideal prosthesis for the small aortic root is yet available. Conventional stented valves are hemodynamically disadvantageous because of higher transvalvular pressure gradients. Stentless bioprostheses were implanted in such patients to evaluate their performance as an alternative to homografts and to conventional mechanical prostheses. MATERIALS AND METHODS: We analyzed 57 patients with small aortic roots who underwent stentless aortic valve replacement (Toronto SPV) from March 1993 to November 1995. All but two patients had aortic stenosis. The mean age at operation was 70.9 (+/-8.2) years. The annular diameter was 18-23 mm (mean 21.4 +/- 1.1 mm) in all patients. Of the 57 patients, 17 received a 23 mm and 40 patients a 25 mm prosthesis. RESULTS: Using the oversizing technique, valve size was adjusted according to the sinotubular junction diameter, allowing a gain in prosthesis size of 2-4 mm to be achieved in all patients. On pre-discharge echocardiography maximum flow velocity was 2.3 +/- 0.4 m/s, maximum pressure gradient was 19.1 +/- 6.8 mmHg, and effective valve orifice area was 1.46 +/- 0.27 cm2. All patients were in NYHA class I or II at discharge. One patient was reoperated due to a folded annulus caused by too much oversizing. At six months follow up there was a significant reduction in pressure gradients and an increase in effective valve orifice areas in relation to a decrease in pre-existing left ventricular hypertrophy. CONCLUSIONS: Stentless bioprostheses show excellent hemodynamics due to their comparably large internal diameter and flexibility. Controlled oversizing is a safe technique without additional complications. As larger valve sizes can be implanted, aortic root enlargement is not necessary. The superior hemodynamic profile of stentless aortic valves is especially advantageous in patients with small aortic roots.
Aged↗
[Value of score systems in heart surgery].
Although numerous scores have been designed to provide stratification of morbidity and mortality outcome by preoperative risk factors and to determine patients at risk from prolonged length of ICU and hospital stay after cardiac surgery, the predictive power of these scores for individual prognosis remains poor. However, scoring in cardiac surgery may be used for a different purpose. With increasing health care costs fast-track intensive care treatment saving ICU resources has become an important issue in cardiac surgery. With the help of scoring systems that can accurately identify low-risk patients who will have a favourable postoperative course a subset of patients eligible for early ward referral can be defined. Thus, scoring may save total ICU days of cardiac surgical patients and reduce costs.
Cause of Death↗
Simultaneous coronary bypass and abdominal aortic surgery in patients with severe coronary disease--indication and results.
In patients with severe coronary artery disease (CAD) abdominal aortic surgery is still associated with high morbidity and mortality rates. Some patients will present with both symptomatic CAD and large, symptomatic abdominal aortic aneurysms (AAA) or end-stage aortic occlusive disease (AOD) that does not allow for a two-stage procedure. We report a series of 29 patients who underwent simultaneous coronary artery bypass graft surgery (CABG) and abdominal aortic surgery (25 AAA, 4 AOD). In the AAA group there were 23 males and 2 females with a mean age of 68 years (50-80). Sixteen patients presented with severe three-vessel disease. Ten patients had unstable angina. Aortic stenosis or insufficiency was present in two and one patient, respectively. Four patients with three-vessel disease and an ejection fraction below 30% presented with end-stage AOD and critical limb ischemia. Coronary bypass graft surgery was performed first. With the patient still on partial cardiopulmonary bypass, abdominal aortic surgery was carried out. Patients received an average of 3.1 coronary bypass grafts. Additionally, three aortic valves were implanted. Fourteen tube grafts and 15 bi-iliacal or bifemoral bifurcation grafts were placed in the abdominal aortic position. Additional vascular surgery was performed in five patients. Intraoperative management was without complication in all but one patient, who had intraoperative myocardial infarction (AOD group). Hospital mortality was 8% (2/25) in the AAA group. There was however substantial hospital morbidity (52.2%). The mean follow-up is 20.5 +/- 2.5 months. The actuarial survival rate at 3 years is 84.9%. It is concluded that combined CABG and abdominal aortic surgery is a reasonable option for patients who present with both severe CAD and symptomatic abdominal aortic disease. The continuation of CPB during aortic surgery may effectively prevent the adverse effects of infrarenal aortic clamping on a failing ventricle.
Actuarial Analysis↗
Open heart surgery in the octogenarians--a study on long-term survival and quality of life.
This retrospective study analyzes the perioperative and long-term survival rate as well as the long-term quality of life of 54 patients (23 f/31 m), aged 80 years or older (80 to 87, mean 82.2, SD +/- 1.79 years), who underwent open heart surgery between January 1986 and December 1993. There were 23 patients with coronary bypass, 21 with aortic valve replacement, 1 with mitral valve replacement, 8 with combined aortic valve replacement and coronary bypass, and 1 with double valve replacement. Preoperatively, 26 of the patients were in New York Heart Association (NYHA) class IV, 28 patients in class III. The in-hospital mortality was 9.3% (5/54) over all and 6.1% (3/49) for elective procedures. Follow-up time ranged from 6 to 91 months (mean 26.2 +/- 16.5). Of 49 discharged patients, 6 (12.2%) died during the follow-up period. At the time of re-evaluation 21 patients were in NYHA class I, 24 patients in class II, and 4 in class III. There was a significant long-term benefit from the surgical intervention in 39 or the 54 patients. Of 43 survivors 41 were able to live on their own and 38 were able to handle their daily routine without help. Two patients were cared for in a nursing home. This long-term analysis demonstrates the benefits of cardiovascular surgery in octogenarians in terms of social integration and quality of life.
Aged↗
Tonsillar carcinoma in the early postoperative course following heart transplantation.
A 45-year-old male with end-stage dilative cardiomyopathy was referred for heart transplantation (HTx). Apart from severe heart disease the patient had an unremarkable medical history. Risk factors were heavy smoking and moderate consumption of alcohol. Preoperative screening including a thorough ENT status did not reveal any other risk factor or contraindication for heart transplantation. HTx was performed three months later. Immunosuppressive therapy consisted of triple-drug therapy and induction therapy with antithymocyte globulin. The patient had an uneventful perioperative course. One month after transplantation the patient developed a rapidly growing squamous cell carcinoma of the left tonsil with local metastasis. Because of the rapid growth and size of the tumor surgical treatment was already impossible at that early time. Despite a course of chemotherapy the tumor continued to grow; treatment was changed to radiation therapy resulting in partial remission. Cyclosporine and azathioprine dosages were reduced at the same time. 9 months following HTx the patient developed a rapidly growing recurrence. As there were no further therapeutic options, immunosuppressive therapy was completely discontinued with the patient's agreement. He died 2 months later. The rapid tumor growth and its early manifestation following HTx suggest a preexistent occult carcinoma. A more extensive and repetitive preoperative screening in HTx candidates who are heavy smokers should be considered.
Carcinoma, Squamous Cell↗
Proposal for a loophole-free test of the Bell inequalities.
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Journal Article↗
Thermal coronary angiography for intraoperative patency control of arterial and saphenous vein coronary artery bypass grafts: results in 370 patients.
BACKGROUND AND AIM OF THE STUDY: Early graft failure is often associated with technical failures and is therefore potentially avoidable. We used thermal coronary angiography (TCA) for intraoperative graft patency control in 370 patients undergoing routine coronary artery bypass graft surgery to determine whether consequent intraoperative bypass graft control may result in improved patency rates. METHODS: The temperature differences generated in between the myocardium and the grafts by injecting cold cardioplegic solution into the proximal end of a vein graft or by warmer blood running through an internal thoracic artery (ITA) graft were detected using three different infrared camera systems. The resulting "heat pictures" were evaluated for anastomotic patency and to outline graft anatomy. RESULTS: A total of 693 vein grafts were visualized. In 9.4% TCA failed to produce usable images. In the remaining 628 grafts, TCA revealed intraoperative patency in 98.8%. Out of 370 ITA grafts, only 14 could not be sufficiently visualized by TCA. Nineteen ITA occlusions (5.3%) were found: 5 intimal flaps; 11 suture imposed strictures; and 3 proximal ITA occlusions. All occluded grafts were subsequently revised or replaced. All sequential ITA as well as 15 right ITA grafts proved to have patent anastomoses. CONCLUSION: Using TCA an early graft dysfunction rate of 1% for vein grafts and 5.3% for ITA grafts could be demonstrated. Most occlusions were due to technical mistakes at the distal anastomosis. TCA outlines grafts and the attached coronaries by temperature differences without the need for a contrast agent. There is no interference with the surgical procedure. It is an ideal, noninvasive method to immediately document the success or failure of myocardial revascularization.
Adult↗
The Toronto SPV bioprosthesis: one-year results in 100 patients.
BACKGROUND: We studied the long-term results of heart valve replacement with the Toronto SPV bioprosthesis. METHODS: From March 1993 until July 1994 the Toronto stentless bioprosthesis was implanted in 100 selected patients with a mean age of 70.7 years. The predominant aortic valve lesion was stenosis in 94 and insufficiency in 6 cases. Eighty-eight patients received a valve 25 mm in diameter or larger. Additional coronary artery bypass grafting was performed in 37 cases. Hospital mortality was 4%. Seventy-four patients were seen at 6 months and 38 patients at 1 year follow-up. RESULTS: Structural deterioration, thromboembolism or hemorrhage were not encountered. Nonstructural dysfunction lead to reoperation in 1 patient. Another patient presented with endocarditis at 1 year postoperatively. There were no other valve-related complications. Echocardiographic mean pressure gradients ranged from 7.7 to 11.1 mm Hg postoperatively. There was a significant decrease in pressure gradients at 6 months of follow-up. Minimal aortic valve incompetence was seen in 3 patients. CONCLUSIONS: The Toronto stentless bioprosthesis has superior hemodynamics and is an excellent alternative to conventional stented bioprostheses. Long-term evaluation has to prove whether this promising new valve can live up to its expectations.
Adult↗
[Trauma and circulatory arrest. 224 preclinical resuscitations in Cologne in 1987-1990].
Posttraumatic cardiopulmonary resuscitation (CPR) is associated with a poor outcome. When evaluating the literature according to the Utstein method, there were only 2 survivors (0.18%) out of 1,135 CPR attempts after trauma (Table 1). Differences in the study populations and levels of prehospital trauma care led us to analyse the results of a physician-staffed prehospital trauma care system in Cologne. METHODS. From January 1987 to December 1990, a total of 49,054 emergency calls were registered using a standardised protocol. Among 9,595 trauma-related calls, 636 patients were found to be pulseless on arrival of the emergency team, 412 of these were pronounced dead. CPR was initiated in the remaining 224 patients, who comprise the study population (defined as 100%). All patients who were admitted to a hospital were followed using a second protocol. RESULTS. CPR in the field was successful in 68 (30.4%) patients, who were then admitted to a hospital; 42 of these died within the first 24 h. Four patients (1.8%) could be discharged from hospital alive and were still living 1 year later, 1 with a lasting neurological deficit (Fig. 1). In 156 (69.6%) cases resuscitative attempts were unsuccessful in the field. CONCLUSIONS. Even in a physician-staffed prehospital trauma care system, the chance of surviving a posttraumatic cardiac arrest is minimal. Survival has to be regarded as an individual fate; the overall results are discouraging. Even though this study analyses the largest population of posttraumatic CPR ever published, prognostic factors could not be identified due to the few survivors. Nevertheless, the result does not justify general omission of CPR after trauma as: (1) prognostic factors for survival have not been identified thus far; and (2) no significant additional costs arise from posttraumatic CPR.
Adult↗
Hemodynamic assessment of the stentless Toronto SPV bioprosthesis by echocardiography.
Since March 1993 the Toronto SPVTM bioprosthesis has been implanted in 100 patients. Our prospective study evaluated the echocardiographic valve characteristics and the influence of the echocardiographic assessment on surgical technique. Transesophageal echocardiography (TEE) was applied before and during surgery, and transthoracic echocardiography (TTE) postoperatively. The average valve size implanted was 26.5 mm. Follow up was complete in 74 patients at six months and in 38 patients at one year. Pre-cardiopulmonary bypass (CPB) TEE valve sizing was accurate by +/- 1 mm in 81 patients as compared to mechanical sizing. Post-CPB valve closure was concentric in 99 patients. Minimal aortic incompetence was present in seven patients at one week, in two patients at six months and in one patient at one year. Mean pressure gradients ranged from 7.7 to 11.1 mmHg postoperatively. Overall mortality was 4%. One patient with non-structural dysfunction and another with endocarditis at one year postoperatively were reoperated successfully. At follow up there was a significant decrease in transvalvular pressure gradients and an increase in valve orifice areas. In 32 patients a decrease in left ventricular posterior wall (LVPW) hypertrophy was found (p < 0.001). There was a decrease in tissue depth and recurrence of the dynamic movement of the aortic root. It is concluded that TEE valve sizing is reliable for early valve selection. Valve incompetence is not a clinically relevant issue using the oversizing technique. Improved hemodynamics at follow up can be explained by remodeling of the aortic root and by a decrease in left ventricular hypertrophy. The excellent hemodynamic profile, resembling native aortic valve function, is impressive and has to be confirmed by long term evaluation.
Adult↗
Variability of serum levels for three oral 8-methoxypsoralen brands.
We conducted a pilot study to investigate the serum level patterns of 3 commercial and internationally introduced 8-methoxypsoralen (8-MOP) preparations in 9 patients for their bioequivalence and registered the interindividual variability of serum levels over 8 h after intake of 30 mg 8-MOP equivalent doses. On average, the highest serum levels (Cmax 120.1, range 235-61 ng.ml-1) were reached as early as 0.5-1 h after ingestion of Geroxalen soft gelatin capsules, whereas lower serum levels were seen after intake of the Oxsoralen hard gelatin capsules (Cmax 82.3, range 154-47 ng.ml-1) and the Mopsoralen tablets (Cmax 81.3, range 172-26 ng.ml-1). The importance of 8-MOP serum level determination for better and efficient PUVA therapy is discussed.
Adult↗
8-Methoxypsoralen serum levels in poor responders to photochemotherapy. Importance of drug formulation and individual factors.
8-Methoxypsoralen (8-MOP) serum levels of psoriatic patients poorly responsive to photochemotherapy (PUVA) treatment (problem cases) were determined by the HPLC method with 11 single blood probes over 8 hours. Abnormally low or deviated serum levels were found in 7 of 11 PUVA problem patients. There was a great interindividually different first-pass effect for 8-MOP in dependence on the galenic formulation of the 8-MOP brand; therefore, the change to another 8-MOP brand with a modern galenic formulation led only to a slight increase of serum levels, and consequently an increase in the 8-MOP dosage was necessary. It is important to be cautious at this point because patients may show an unproportional increase of 8-MOP serum levels due to the individually limited capacity of biotransformation. The studies of the authors reaffirm the necessity of the determination of 8-MOP serum levels in problem cases of PUVA therapy.
Biological Availability↗