Biomedical subjects

J Ennker

Publications and source records attributed to J Ennker.

At least 37 records · Page 2Linked to original sources

PubMed2001

[Risk of perioperative mortality and complications following biological aortic valve replacement in elderly patients: stented vs. unstented prostheses].

Recently published studies suggest that the hemodynamic advantage of stentless bioprostheses in comparison to stented bioprostheses positively influence the long-term survival after aortic valve replacement. However, the more complex and time consuming implantation technique may increase the risk of operative death. Between April 1996 and September 2000, 201 patients with the mean age of 75 +/- 5 years underwent aortic valve replacement (AVR) with a stentless Medtronic Freestyle Bioprosthesis (FP) and 166 patients with a mean age of 77 +/- 5 years received a stented Medtronic Mosaic Bioprosthesis (MP). Patients requiring concomitant procedures other than coronary artery bypass grafting (CABG) were excluded. The operative mortality was 3.5% after AVR with the FP and 6% after AVR with the MP. Multiple logistic regression analysis considering the different patient populations revealed no increased risk of operative death after AVR with FB (p = 0.46). Previously heart operations (p = 0.046) and emergency operation (p = 0.022) were risk factors for operative death after AVR with the biological bioprostheses. The risk for postoperatively neurological impairment (p = 0.15) and other complications (p = 0.46) was furthermore not increased after implantation of a Freestyle stentless valve. The risk of delayed mobilization (p < 0.001) was 2.4-fold increased for patients after AVR with the Freestyle valve. A positive influence on survival due to the implantation of a stentless Freestyle valve could not be shown within the observed period. However, in spite of the more complex and time-consuming operation technique, the risk of operative death and postoperative complications is not increased after aortic valve replacement with the stentless FB.

Age Factors↗

PubMed2001

[Perioperative complications after heart valve replacement].

These days, the majority of perioperative complications resulting from operations on heart valves are more a consequence of the increasing age and morbidity of the patients and, despite all cardiac surgical and intensive care innovations, are still more the effect of the procedure on the other organ systems of the patient than being purely of a surgical nature. The surgical short- and long-term results after heart valve operations are significantly influenced by the early detection and adequate management of these manifold complications.

Adult↗

PubMed2000

[Aortic valve replacement in 80- and over 80-year-old patients. Short-term and long-term results].

Due to demographic changes in average life expectancy, the age of patients undergoing cardiac surgery is increasing as well. We have reviewed the short- and long-term outcome in patients over 80 years of age after aortic valve replacement. From 01 Jan 1995 until 31 Dec 1998, 105 patients (76 women, 29 men between 80 and 89 years, median: 83) underwent aortic valve replacement. 42% presented with aortic stenosis, 58% with combined valve disease with leading stenosis. 53% (group A) received isolated valve replacement, 47% (group B) underwent myocardial revascularization as well. The in-hospital mortality rate was 8.9% for group A and 14.3% for group B. The follow-up time ranged between 10 and 243 weeks (median: 112 weeks). None of the patients had to be reoperated for prosthetic valve dysfunction or endocarditis. Bleeding complications due to anticoagulant therapy were not observed. Of the 11 deaths during the follow-up period, 5 (45%) were cardiac in nature and 2 (18%) related to stroke. Actuarial survival rates for group A were 98, 95 and 88% at 1, 2 and 3 years, and for group B 92, 84 and 84%, respectively. Permanent nursing care was not required 1 year after the operation by 98% of patients in group A (2 years: 95%, 3 years: 88%) and by 100% of patients in group B (2 years: 95%, 3 years: 88%). At an interval of 1 year after the operation 98% of patients in group A had not been hospitalized as a result of cardiac disorders (2 years: 98%, 3 years: 94%). The rates for group B were 90, 82 and 82%. Compared with younger age groups, aortic valve replacement in patients 80 years of age and older is associated with a distinctly increased mortality and morbidity. However, our data suggest that considering the poor prognosis of conservative therapy of symptomatic aortic valve disease, the functional status as well as life expectancy in this age group seems to be positively influenced by aortic valve replacement.

Aged↗

PubMed2000

[Isolated coronary bypass operation in the 9th decade of life].

The average age of patients undergoing cardiac surgery has increased continuously during the last three decades due to a progressively increasing number of older people in the population and the advances in operative and perioperative treatment in open heart surgery. Consequently we have investigated the short- and long-term results of isolated myocardial revascularization in patients who are in their ninth decade of life. Between 1 January 1995 and 31 December 1998, 121 patients (51 women, 70 men, age 80 to 88 years, median: 82 years) underwent isolated coronary artery bypass grafting. As part of the revascularization, a unilateral internal mammary artery graft (IMA) was used in 87% of cases. The in-hospital mortality was 6.6%. Analysis of predictors of mortality unveiled the following factors: ejection fraction less than 50%; history of recent left ventricular failure; extent of coronary artery disease; perioperative use of an intraaortic balloon pump (IABP) and symptomatic pericardial effusion. Use of the IMA revealed no influence on in-hospital mortality. The median follow-up time was 20 months (range: 2-48 months). Survival rates after 1, 2, and 3 years were 93.1%, 87.3% and 73.7% for women and 86.9%, 82.5% and 65.1% for men. These survival rates were comparable with those of the entire 82 year old population. Predictors for late death were male gender, history of stroke, history of arterial embolism, and postoperative pulmonary failure resulting in mechanical ventilation. During the follow-up period myocardial infarcts were subsequently not observed. Freedom from angina after 1, 2 and 3 years was 90.1%, 82.6% and 78.1%, respectively. At an interval of 1 year after the operation 87.6% of patients had not been hospitalized as a result of cardiac disorders (2 years: 80.1%, 3 years: 73.2%). Permanent nursing care was not required 1 year after the operation by 94.3% of patients (2 years: 91.5%, 3 years: 91.5%). Four percent of the survivors suffered from permanent delirium, 3% from depression, 5% from lack of concentration, and 6% from vertigo. In summary this study has revealed that, in patients over eighty years of age suffering from ischemic heart disease, coronary artery bypass grafting has acceptable short- and long-term results. Yearly mortality rates during the first 3 years after the operation are comparable with the expected mortality rate in an age-matched population.

Aged↗

PubMed2000

[Multiple myocardial revascularization on the beating heart: risks, benefits and outlooks].

INTRODUCTION: Avoidance of extracorporeal circulation during beating heart surgery (OP CAB = Off-Pump Coronary Artery Bypass Surgery) for aortocoronary bypass grafting (ACBG) is gaining increasing importance in modern cardiac surgery. With the development of new mechanical stabilization devices, the revascularization of the posterior wall of the heart and the distal right coronary artery became feasible. Especially high-risk patients with multiple risk factors for open heart surgery will profit from this approach, because the negative effects of the extracorporeal circulation are avoided. METHODS: From 7/97 until 12/99 a total of 158 patients with multivessel-coronary artery disease were operated on the beating heart. In the same time course, a total of 2869 patients were operated conventionally using the extracorporeal circulation as a standard procedure. RESULTS: Due to patient selection, the two groups differ in the preoperative data concerning previous neurologic deficits. None of the patients in the OP CAB group suffered a permanent neurologic deficit after the operation, whereas in the CAB group the rate of stroke was 1.3%. The rate of temporary neurologic deficits, such as TIA (temporary ischemic attack) or PRIND (prolonged reversible neurologic deficit), was higher in the OP CAB group due to patient selection. No surgcially associated aortic dissection was seen in the OP CAB group. CONCLUSIONS: This and other studies have shown the effectiveness of OP CAB surgery concerning perioperative complications and survival rates. Especially high-risk patients with multiple risk factors for a cardiac operation profit from a beating-heart operation avoiding extracorporeal circulation. The question in how far the higher rate of reoccurring angina and the larger number of interventional treatments in OP CAB patients reported in the literature are due to the learning curve remains unanswered. Long-term studies will show whether the result of beating heart surgery is as good as the result of conventional "on-bypass" surgery.

Coronary Artery Bypass↗

PubMed1999

[Arterial myocardial revascularization in the 9th decade of life. Personal results and review of the literature].

The rate of the population being 80 years of age and even older, has an increasing tendency in the Federal Republic of Germany. In 1996, a total of 87,372 patients received surgery supported by the heart-lung-machine, 2,383 patients out of these (2.7%) were 80 years of age and older. In view of the limited life expectance, the arterial revascularization in this age category is faced with controverse discussions. We analysed our patients in relation to this aspect. Between January 1, 1995 and June 30, 1997, 4,338 patients underwent surgery supported by the heart-lung-machine. Hundred and fifty-five out of these (3.6%) were in the 9th decade of life. Seventy-seven patients out of the 155 (49.7%, 34 women, 43 men, 80 to 88 years old, mean: 82 years of age) underwent an isolated myocardial revascularization. We performed 55 (71%) elective, 16 (21%) urgent and 6 (8%) emergency surgeries. Twelve patients (15.6%) solely received venous bypasses (Group I), 65 (84.4%) additionally also received unilateral bypasses of the internal mammaria artery (IMA) (Group II). Three patients died at our facility (3.9%), 3 further patients died during the follow-up treatment in outlying hospitals, the in-patient mortality rate in Group I therefore presented a rate of 8.3%, in Group II 7.7% and in total, a rate of 7.8%. In 1996, the in-patient mortality rate could be reduced to 3.6%. The follow-up observation time ranged between 7 and 138 weeks (median 44 weeks). The survival rate for patients with an IMA-bypass after 1 year was 86.3%, after 2 years 77%, and for the entire collective 85.3% and 75%. Whereas 96% of the patients could pre-operatively be related to Class III or IV of the NYHA-classification, 55 of the 63 survivors (87%) belonged to Class I (6%) or II (81%). Two Group I patients (22.2%), 3 Group II patients (5.6%) and 7.9% of the total collective complained about repeated angina symptoms. The myocardial revascularization with the internal mammaria artery performed on patients in the 9th decade of life, achieves an acceptable morbidity and mortality compared to solely venous coronary bypasses. The more prolonged follow-up observation period will clarify, whether the arterial myocardial revascularization also proves to be the superior method in this age category.

Aged↗

PubMed1999

[Dissection of the sinus valsalvae aortae as a complication of coronary angioplasty].

The localized dissection of the aortic sinus of valsalvae is a rare complication of coronary angioplasty involving mainly the right coronary artery. In all previously published case reports (n = 10), a coronary dissection provided the entry door with subsequent retrograde progression of the dissection into the aortic root. In our case of a 75 year old female patient with symptomatic three vessel disease, a chronic occlusion of a proximal RCA could not be passed by a coronary guide wire. During the procedure an aneurysm of the aortic sinus occurred near the ostium of the RCA. The patient was referred for immediate aortocoronary bypass surgery. The inspection of the aortic sinus showed, as the entry of the dissection, a small puncture hole, adjacent to the ostium of the RCA, probably caused by the stiff 0.014 coronary guide wire, and no retrograde dissection of the right coronary artery. The localized dissection could easily be fixed by a prolene suture during the bypass surgery procedure with an uncomplicated postoperative course. If the entry of the dissection is within the coronary artery, forced contrast injections and balloon inflations promote its propagation and should be avoided. If the entry could be sealed by an intracoronary stent and the aneurysm remained localized, confirmed by echocardiographic controls, the aneurysm tends to resolve spontaneously in the first month without need for surgery. A progression of the aneurysm into the ascending aorta or a failure of an entry sealing with a stent is an indication for urgent surgical treatment.

Aged↗

PubMed1999

The disproportion of female and male surgeons in cardiothoracic surgery.

In ancient times, female medical practitioners and female surgeons were well known. With the introduction of medicine as an academic course and the ban on women studying, the medical career became virtually impossible for women. This condition changed with the general admission for women to colleges, in Germany in 1908. The current situation of women in surgery is presented here, with cardiovascular surgery as an example. Of 302 active cardiothoracic and cardiac surgeons 4.6% are female. According to an inquiry of all German heart institutes, there are 20 female senior registrars and 27 female surgeons as well as 162 female assistants. Most of the medical directors do have a positive opinion about female surgeons, but criticize that only a few women who apply for actually finish surgical training. One reason for this may be the greater difficulties for women to take care of a family and become a surgeon simultaneously. In this regard, an improvement in the position of female doctors is desirable.

Cardiology↗

PubMed1999

Errors of the backextrapolation method in determination of the blood volume.

Backextrapolation is an empirical method to calculate the central volume of distribution (for example the blood volume). It is based on the compartment model, which says that after an injection the substance is distributed instantaneously in the central volume with no time delay. The occurrence of recirculation is not taken into account. The change of concentration with time of indocyanine green (ICG) was observed in an in vitro model, in which the volume was recirculating in 60 s and the clearance of the ICG could be varied. It was found that the higher the elimination of ICG, the higher was the error of the backextrapolation method. The theoretical consideration of Schröder et al (Biomed. Tech. 42 (1997) 7-11) was proved. If the injected substance is eliminated somewhere in the body (i.e. not by radioactive decay), the backextrapolation method produces large errors.

Artifacts↗

PubMed1999

Optimizing deconvolution techniques by the application of the Münchhausen meta algorithm.

A deconvolution applied to disturbed data often gives poor results, due to fundamental difficulties associated with ill-posed problems. Many numerical and theoretical methods have been invented to circumvent this phenomenon. Their performance varies, depending on the given problem and data. The main aim of this paper is to provide a decision rule for choosing a method for deconvolution and application of this method to the same data. We have called this meta-algorithm Münchhausen. In this paper we introduce and describe for the first time the basic principle of artificial disturbance of the data in the set-up of deconvolution. We demonstrate some interesting features of the random procedure Münchhausen, such as the non parametric set-up, robustness to disturbance of the data and last but not least good performance.

Algorithms↗

PubMed1999

Simultaneous myocardial revascularization and aortic valve replacement: stentless versus stented bioprostheses.

Implantation of stentless aortic valve prostheses is more time-consuming than implantation of conventional stented bioprostheses. Simultaneous myocardial revascularization can result in a considerably prolonged operation time. We reviewed our patients with regard to surgical aspects in the specific patient cohorts. From April 1996 to April 1999, 303 patients were operated for aortic valve disease with or without concomitant coronary artery revascularization. Mean age was 75 years, ranging between 36 and 90 years. Using the Medtronic Freestyle valve, the following techniques of implantation were used: subcoronary technique, 163 patients, 61.5%; root inclusion technique, 7 patients, 3.5%; total root replacement, 30 patients, 15%. Total hospital mortality rate was 5.6%, reflecting age and concomitant disease of these patients. For isolated aortic valve replacement, the mortality rate was 4.7% and 6.7% for combined procedures. Coronary artery patients who are not suitable for stentless valve implantation owing to extensive aortic root calcification have a higher perioperative mortality rate. Compared with the isolated valve replacement and despite more extensive surgery and prolonged operative time, simultaneous myocardial revascularization in patients with stentless prostheses implantation can be performed without an increased risk.

Adult↗

PubMed1996

Characteristics of patients younger than 40 years of age operated for coronary artery disease.

This study reviews data on 126 patients (107 men, 19 women) younger than 40 years of age who underwent coronary artery bypass grafting during an 8-year period. They were matched to a control group which also consisted of 126 operated patients but exceeding the age of 39. The majority of the patients in the study group presented with angina; 85.9% were CCS III or IV compared to 61.9% in the control group. More than 3 fourths of the patients (80.5%) had experienced at least 1 myocardial infarction. There was a high incidence of coronary risk factors, especially hyperlipoproteinemia (88.5%), smoking (85.1%), and hypertension (83.1%), whereas in the control group these risk factors occurred in only 49.2%, 21.4%, and 53.2% of the patients, respectively. Other risk factors like diabetes mellitus or family history of coronary artery disease were found in 10.3% and 48.6% of the young patients. While 23.0% of the patients had varying degrees of left main stenosis, 9.5%, 18.3%, and 72.2% had single, double, and triple vessel disease, respectively. Left ventriculograms showed serious functional impairment (ejection fraction less than 40%) in 22.2% of the patients. A total of 286 saphenous vein grafts (2.3 grafts per patient) and 126 internal mammarian grafts were implanted, whereby an internal mammarian graft was always used. In 6 patients we used an intermittent mechanical support system (intraaortic balloon pump in 5 patients and an assist device in 1). In-hospital mortality rate was 1.6% (2 patients); long-term mortality rate 5.2% (mean follow-up interval 54 +/- 20 months). Actuarial survival was 93.0%, 89.8%, and 89.8% at 3,5, and 7 years, respectively. Survival in patients with normal and impaired ejection fraction was significantly different (p < 0.035) for 5-year and 7-year survival (100% vs. 81.8%). We observed encouraging intermediate term results in young adult patients after coronary revascularization. This may have been due to the consistent use of internal mammary artery grafts.

Actuarial Analysis↗

PubMed1994

Formaldehyde-free collagen glue in experimental lung gluing.

Because of the well-known limitations of the adhesive strength of fibrin glue, it is imperative to develop a stronger glue with acceptable biocompatibility. This was accomplished by removing the formaldehyde component from gelatin-resorcinol-formaldehyde glue and replacing it by two less toxic aldehydes--pentanedial and ethanedial. To evaluate the adhesive strength of this new glue, GR-DIAL, lung incisions in rabbit hybrids were glued together. Each group (n = 5) was examined histologically after 2 days and 1, 2, and 4 weeks. The glue disintegrated gradually with good bioresorption when the incision was closed with a thin layer of glue. The healing process was favorable, indicating good biocompatibility. Therefore, GR-DIAL glue is capable of enhancing the use of surgical glues in the field of thoracic surgery by enabling surgeons to close larger parenchymal lesions than with fibrin glue.

Animals↗

PubMed1994

The impact of gelatin-resorcinol glue on aortic tissue: a histomorphologic evaluation.

PURPOSE: Although gelatin-resorcinol-formaldehyde glue has been used to treat acute aortic dissections for some time, concerns about formaldehyde's mutagenicity and carcinogenicity made it imperative to develop a new glue compound. Gelatin-dialdehyde glue was produced by omitting the formaldehyde component and replacing it with two less toxic aldehydes, glutaraldehyde and glyoxal. This study evaluated the histomorphologic effects of the new glue through in vivo use on the aortic tissue of domestic pigs. METHODS: Each animal's infrarenal aorta was glued around an implanted prosthesis. Histomorphologic evaluation was performed after operation after 1 and 4 weeks. RESULTS: The results demonstrated that the clinically observed tanning effect can be attributed primarily to the disintegration of the fiber texture, specifically collagenous, as well as smooth muscle fibers, and to the reciprocal alterations of the proteoglycan interstitial substance in the aortic wall. Macroscopic, microscopic, and electron microscopic analysis of the gluing process revealed an adequate healing process without any morphologically significant difference between formaldehyde and formaldehyde-free gelatin-resorcinol glue. CONCLUSIONS: Gelatin-dialdehyde glue is able to produce the same effects in the area of the aortic wall as the substantially more toxic gelatin-resorcinol-formaldehyde glue and thus could be recommended for clinical trials for treating acute aortic dissections thus far yielding excellent initial results.

Animals↗

PubMed1994

Coronary artery bypass grafting and heart transplantation in end-stage coronary artery disease: a comparison of hemodynamic improvement and ventricular function.

Heart transplantation has now become an accepted treatment for end-stage coronary heart disease (CAD). However, the limited supply of suitable donor organs imposes constraints upon the decision of whether patients are selected for transplantation or for coronary artery bypass grafting (CABG). From April 1986 until the end of March 1992, 265 patients with end-stage CAD involving left ventricular ejection fraction (LVEF) 10% to 30% and predominant angina pectoris underwent CABG. All patients received an average of 2.9 +/- 0.3 venous grafts. Intraaortic balloon pumps were implanted in 30 patients (11.3%) who began to develop low cardiac output syndrome intraoperatively. The actuarial survival rate was 87.8% after 2 years and 86.9% after 3 years. LVEF was measured in 35 patients via left heart catheterization 12 months after their operations and was found to have increased from a mean of 23.8% to 38.1%. Left ventricular end-diastolic pressure had decreased from 16.2 mmHg to an average of 12.1 mmHg. Swan-Ganz catheterization was performed on 120 patients 6 months postoperatively. The pulmonary wedge pressure had reduced significantly from 18.1 mmHg to a mean of 12.7 mmHg (p < 0.01). From 1990 until the end of March 1992, 55 patients with CAD and predominant heart failure received transplants. Their 2-year survival rate was 66.3%. Mean LVEF was 55.6% postoperatively. We conclude that CABG is adequate for patients who have end-stage CAD and angina pectoris symptoms, and that it significantly improves hemodynamic functions. Patients suffering predominantly from heart failure (NYHA Class IV) can be transplanted and subsequently regain normal heart function.

Actuarial Analysis↗

PubMed1994

Diagnostic evaluation and surgical management of the aberrant right subclavian artery.

A case of dysphagia and dyspnea secondary to compression of the esophagus and the trachea by an aberrant right subclavian artery is presented. As the pathology of the aberrant right subclavian artery is extremely diverse, the diagnosis without radiologic investigation is hardly feasible. Conventional angiography of the aortic arch may be avoided by 3-dimensional magnetic resonance angiography, that is a suitable noninvasive method to diagnose and visualize the vascular pathology and the postoperative results after corrective vascular surgery. With the use of a Gore-Tex prosthesis the right aberrant subclavian artery was successfully translocated to the ascending aorta through a mid-sternal, transmediastinal approach. In contrast to previous reports the retro-esophageal vascular segment was kept in situ. The literature is reviewed with the reference to the diagnostic procedure and the treatment of dysphagia lusoria.

Adult↗

PubMed1993

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%.

Adult↗

PubMed1992

First clinical experiences with a new angioscopic system for diagnosing peripheral vascular changes.

Conventional angiography allows a global view of regional vascular anatomy but precise information can only be deduced indirectly using contrast medium. The use of the three-dimensional picture of angioscopy, however, allows a direct evaluation of the vascular system. In order to extend our experiences with angioscopy, we employed a new micro-cardio-angioscopic system which consists of four components: a CCD color camera (360,000 pixels); a highly flexible optical probe which can be resterilised (1.4-0.6 mm diameter) incorporating 10,600-6,000 glass fibers, with a viewing angle of 140 degrees, 70 degrees, and 50 degrees and a focusing system that allows a distance from 2 mm to infinity; a high power light source and an insertion catheter with inflatable balloon. Using a known technique (intermittent blood-flow blockage and continual rinsing with NaCl solution), 36 cases involving 27 patients were examined before and after desobliteration of the femoral artery. In 88% of the cases it was possible to control the result of the intervention by angioscopy. Smaller intimal lips, the thrombotic wall, and intimal ruptures were clearly visible. Quantification of the stenoses was also successful in 88% of the cases, and in 8 patients the angioscopic findings deviated from the conventional angiogram. In 14% of the cases, angioscopic examination of the recanalisation result showed that thrombolytic therapy was necessary. Angioscopy offers the possibility of qualitative vascular diagnosis. It is a valuable addition to angiography.

Angioplasty, Laser↗