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Biomedical subjects

S Hagl

Publications and source records attributed to S Hagl.

At least 163 records · Page 9Linked to original sources
PubMed1991

Significance of the subvalvular apparatus for left-ventricular dimensions and systolic function: experimental replacement of the mitral valve.

To study the significance of the subvalvular apparatus for left-ventricular performance in mitral valve replacement, a new experimental model was developed. In 21 dogs St. Jude prostheses were implanted in the mitral position preserving the chordae tendineae and the papillary muscles by plicating and fixing the mitral leaflets with the prosthesis on the valvular annulus. Flexible steel wires were slung around the chordae tendineae of the anterior and the posterior papillary muscle separately and passed through the left ventricular wall via insulating plastic cannulas. Left-ventricular dimensions and global systolic function were measured during volume loading with blood before and after severance of the chordae tendineae by external application of electrocautery to the steel wires. Thus the heart continued beating without any interference following loss of the subvalvular apparatus. The external left ventricular diameters in the major and minor axis were determined by sonomicrometry. Left-ventricular systolic and diastolic pressures were measured by catheter tip manometers, stroke volume by electromagnetic measurements of flow in the ascending aorta. When the chordae tendineae had been cut, left-ventricular end-diastolic diameters in the major axis were increased ( + 2%), in the minor axis decreased (-1%) at any left-ventricular end-diastolic pressure. Systolic shortening of the major axis diameter was considerably reduced (20-27%) at any left-ventricular end-diastolic pressure following severance of the chordae tendineae. Significant increase of the systolic shortening in the minor axis diameter occurred at preload levels of 3-6 mmHg (15-8%), while at higher left-ventricular end-diastolic pressure of 7-8 mmHg no significant changes were present.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Entodermal inclusion cyst of the tricuspid valve.

This is a report on an epithelial inclusion cyst covering the septal leaflet of the tricuspid valve. The tumor was an accidental finding in a 5 1/2 years-old boy with congenital heart disease including double-chambered right ventricle, ventricular and atrial septal defects and subvalvular aortic stenosis. Histological examination showed a two-layered ciliated epithelium, typically present in the respiratory system. Embryologic tissue heterotopia arising from sequestered entodermal elements from the primitive foregut during cardiac organogenesis is a possible explanation for the locality and histology of the tumor. To our knowledge, a similar case has never been presented before.

Child, Preschool↗
PubMed1991

Analyzing contractile responses in demembranized pig papillary muscle fibres: the influence of calcium, resting force, and temperature.

The influence of calcium, resting force and temperature on the contractile behaviour in isolated demembranized ("skinned") pig papillary muscle fibers (n = 36) was analysed. Demembranisation excludes the influence of any membrane related processes on the contractile response as the myofilaments are in direct contact with the bathing medium. Resting force (1 mN-9 mN), temperature (22 degrees C or 32 degrees C) and pCa 7.0-4.3 were varied and the contractile response was analyzed by studying the time constant and the extent of post vibration force recovery (PVFR) of the activated preparations (the vibration method). Additional constant-load experiments and detection of sarcomere-length were carried out. There was an inverse-linear relationship between time constants of post vibration force recovery and maximum shortening velocity as estimated by constant load experiments. Resting force affected the extent of force development but not the time constant of post vibration force recovery and modulated the pCa-force relationship without altering the calcium concentration required for half-maximal activation (calcium sensitivity). In contrast lowering the bath temperature from 32 degrees C to 22 degrees C caused a significant leftward shift of the pCa-force relationship potentially due to changes of the contractile filaments' calcium sensitivity. The effect of temperature on the myocardial contractile system is of special interest as hypothermia is frequently used in cardiac surgery. Analysis of alterations of the contractile proteins' calcium sensitivity during the rewarming period of the patient may provide further insight in the pathophysiology of reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Actins↗
PubMed1991

Three-dimensional presentation of cardiac morphology.

The results of a research project aiming to visualize cardiac anatomy in a 3-dimensional form for surgical planning are presented. Based on electronic data processing within a local area network environment, serial slices of CT- and MRI-machines were used to construct a 3-dimensional data cube that was illuminated by calculated sources of light. Light rays were traced through the entire "data volume". Mathematically following each pathway of light through the space, the intensity of changes along this path were calculated. The results of applying this "Heidelberg Ray-tracing Technique" to cardiac anatomy are 3-dimensional "computer movies" that appear on any workstation within a computer network. Using special software, the surgeon can "walk" in any direction through the heart or he can break it into two or more parts in order to analyze regions of interest in detail. Even small structures such as papillary muscles, bifurcations, coronary arteries and cusps of cardiac valves become visible. This new technique may enable the surgeon to open the heart prior to surgery on the computer monitor working with a visualized model that corresponds to the visual experience of his daily intraoperative practice.

Cardiac Surgical Procedures↗
PubMed1991

Performance of dynamic cardiomyoplasty related to the functional state of the heart.

Cardiomyoplasty (CMP) was performed with the left Latissimus dorsi in five beagles (group 1) with intact hearts and seven foxhounds (group 2) in whom the left ventricle was enlarged by 31 +/- 11.9% of cross-sectional area. Ventricular function curves were constructed at filling pressures ranging from 15-40 mmHg (group 2). Myocardial contraction patterns were investigated by epicardial 2-D echocardiography. Skeletal muscle contraction caused a significant increase in aortic pressure, dP/dt, stroke volume, work and performance in all animals. Function curves were shifted upward in a parallel manner. Echocardiography showed an increase of the LV cross-sectional delta area of 14.8% +/- 5.8% (group 1) and of 39.5% +/- 15.1%, and approximation of the edges of the wall defects (group 2). In conclusion, dynamic CMP as applied in this acute model, increased the performance of normal canine hearts and hence, a model of cardiac failure may not be a prerequisite for the investigation of certain technical aspects of CMP. In the failing heart, a parallel upward shift of myocardial function curves suggested increased performance of the heart/skeletal muscle complex over a wide range of filling pressures. However, the descending limb of the function curve with increasing filling pressures was observed despite skeletal muscle contraction. Hence, similar to other assist systems, the residual function of the heart may be of considerable importance in the overall performance of dynamic CMP.

Acute Disease↗
PubMed1991

Non-invasive assessment of perioperative myocardial cell damage by circulating cardiac troponin T.

Troponin T is a unique cardiac antigen which is continuously released from infarcting myocardium. Its cardiospecificity as a marker protein might be particularly useful in assessing myocardial cell damage in patients undergoing cardiac surgery. Therefore, circulating troponin T was measured in serial blood samples from 56 patients undergoing cardiac surgery and in two control groups--22 patients undergoing minor orthopaedic surgery and 12 patients undergoing lung surgery by median sternotomy. In both control groups no troponin T could be detected, whereas activities of creatine kinase were raised in all 12 lung surgery controls and activities of the MB isoenzyme were raised in five of the 12 patients in the lung surgery group and in four of the 22 patients in the orthopaedic surgery group, respectively. All the patients undergoing coronary artery bypass grafting (n = 47) and cardiac surgery for other reasons (n = 9) had detectable concentrations of troponin T. Five patients had perioperative myocardial infarction detected as new Q waves and R wave reductions. In these five patients troponin T release persisted and serum concentrations (5.5-23 micrograms/l) reached a peak on the fourth postoperative day. In the 51 patients without perioperative myocardial infarction serum concentrations and the release kinetics of troponin T depended on the duration of cardiac arrest. In patients in whom aortic cross clamping was short troponin T increased slightly on the first postoperative days; in patients with longer periods of aortic cross clamping troponin T concentrations were higher and remained so beyond the fifth postoperative day. In patients with non-specific changes on the electrocardiogram troponin T concentrations were significantly higher on days 1 and 4 after operation than in patients with normal postoperative electrocardiograms(11.2 (5) and 4.5 (2.6) v 8.2 (3.4) and 2.9 (1.6) 1microg/l). Serum concentrations of troponin T showed some myocardial cell damage in every patient undergoing cardiac surgery. The persistent increases that were more common in patients with longer periods of cardiac arrest must have been caused by damage to the contractile apparatus. These results suggest that perioperative myocardial cell necrosis may be more common than indicated by changes of the QRS complex on the electrocardiogram.

Acute Disease↗
PubMed1990

Efficiency of a computer network in the administrative and medical field of cardiac surgery. Concept of and experience with a departmental system.

We report on a pilot project implementing electronic data processing (EDP) in the Department of Cardiac Surgery of the University of Heidelberg, based on a concept of complete integration of a medical database system into everyday clinical routine. A computer network was installed and has been in use since August 1988 as a department system supporting both the administrative and the medical side of the department (documentation, information, research, archives, organization, secretarial office, billing, statistics and communication). With a computer-assisted documentation system and standardized data acquisition, nearly 80% of letters and reports on operations are written automatically without any further need for dictation. Automatic computer controlled follow-up has been initiated to cover all patients operated on in our hospital. The complete integration of a new method of clinical documentation and EDP into everyday clinical routine and the extensive use of computer-derived information have proved to be significant advances. Our practice of computer-assisted information management and departmental organization serves the patient by; (1) providing up-to-date valid information for the clinical staff; (2) establishing and stabilizing contact and communication with physicians elsewhere, e.g. cardiologists; (3) facilitating pre- and postoperative contact with patients; (4) helping to optimize medical treatment by routine statistical data analysis (quality assurance); (5) creating a clear and logical computer-assisted departmental organizational structure; (6) permitting long-term evaluation of operative results based on a standardized computer-controlled follow-up procedure; (7) improving the quality of medical and administrative data.

Cardiac Surgical Procedures↗
PubMed1990

Preservation versus severance of the subvalvular apparatus in mitral valve replacement: an experimental study.

Preservation of the subvalvular apparatus in mitral valve replacement has been suggested to improve postoperative left ventricular performance. As it is difficult to quantify the change in left ventricular performance clinically, an experimental model was devised to demonstrate the contribution of the subvalvular apparatus to left ventricular function. In eight dogs mitral valve replacement (St. Jude prostheses) was performed, preserving the subvalvular apparatus by plicating the leaflets with the prosthesis on the mitral annulus. Left ventricular function was assessed during volume loading with blood before and after cutting the chordae tendineae by means of electrocautery applied via flexible wires slung around the chordae and exteriorized through the left ventricular wall. Left ventricular internal diameters were measured by sonomicrometry. End-diastolic volume (LVedV) and stroke volume were determined by dye dilution and left ventricular pressure (LVP) by cathter tip manometer. The results showed that after cutting the chordae the heart rate did not differ from the pre-cut values at any LVedP. The peak left ventricular pressure was only significantly reduced at an LVedP of 5 mmHg and minor axis diameters were only increased at an LVedP of 9-12 mmHg. Significant changes were observed, however, in LV dP/dtmax (= maximum rise of LVP) (-15%), major axis end-diastolic diameter (+10%) and systolic shortening (-40%), end-diastolic volume (+18%) and ejection fraction (-16%) at any LVedP, and stroke volume (-24%) at any LVedV.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Intraoperative diagnosis--measuring heart time volume and assessment of shunts].

Intraoperative measurement of hemodynamics provides objective data supporting improvement of surgical and anaesthesiological treatment. Several methods including the thermodilution method, application of ultrasonic flow meters, use of the computed pressure gradient technique, application of transoesophageal color flow mapping and other cardiovascular applications of ultrasound are discussed with respect to their benefits and limitations in a clinical routine environment in cardiac surgery. According to our experiences the application of intraoperative transoesophageal doppler echocardiography and use of electromagnetic flow measurements are today the methods of choice. However, methodological limitations have to be regarded and additional intraoperative and clinical data are necessary whenever semiquantitative measurements of ultrasound techniques are used as basis for intraoperative judgement on the hemodynamic situation.

Cardiac Output↗
PubMed1990

[Primary right atrial leiomyosarcoma in an adult].

Primary leiomyosarcoma of the heart is very rare, and in most cases the diagnosis is performed during postmortem examinations. We report on a 71-year-old woman with a large leiomyosarcoma of the right atrium. The preoperative diagnosis of cardiac tumor was made by 2-D echocardiography, transesophageal echocardiography, computed tomography, and MR-imaging, and was confirmed by histological and immunhistological findings of the resected part.

Actins↗
PubMed1990

The influence of extracorporeal circulation and hemoseparation on red cell deformability and membrane proteins in coronary artery disease.

Extracorporeal circulation and hemoseparation may lead to coupled mechanical and chemical blood trauma and thus influence red cell deformability. Ten patients with coronary artery disease underwent coronary bypass. Patients' blood samples were drawn preoperatively, after extracorporeal circulation, and after hemoseparation. Ten healthy adults served as control subjects. Red blood cell deformability was determined by direct microscopic observation of red blood cells subjected to shear stresses of 1.2 to 13.3 Pa with a counter-rotating rheoscope. Red cell membrane proteins were separated by one-dimensional polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. At 1.2 Pa, preoperative red cell deformability was significantly greater in patients with coronary artery disease than in control subjects. Neither extracorporeal circulation nor hemoseparation changed red cell deformability significantly. Electrophoretic separation of membrane proteins failed to show any quantitative or qualitative differences between patients and control subjects. Moreover RBC membrane proteins of red blood cells in the patients were not altered as a result of extracorporeal circulation or hemoseparation. The preoperatively increased red cell deformability in the patients may be drug-induced. Our data suggest that the extracorporeal circulation and hemoseparation techniques used in this study do not lead to red blood cell damage.

Blood Transfusion, Autologous↗
PubMed1989

[Peracute constrictive, idiopathic pericarditis--a case report of an acute life-threatening disease picture].

Generally, idiopathic pericarditis is considered a benign, self-limiting disease. Frequently, the exsudative phase of the disease is followed by a mild form of transitory constriction of the pericardium. The case reported here shows an unusual course of the disease. Shortly after the symptoms of exsudative pericarditis subsided a life-threatening form of pericardial constriction developed within weeks. In case of chronic pericardial constriction perioperative mortality for partial pericardiectomy is not insignificant. This is a result of myocardial damage that is difficult to assess prior to surgery. For that reason a partial pericardiectomy should be attempted as early as possible, even in cases with acute pericardial constriction.

Acute Disease↗
PubMed1989

[The significance of heart rate for stress hemodynamics following heart transplantation].

Since 1985, orthotopic heart transplantation had been carried out in 20 patients. Seventeen patients are still alive. 341 +/- 156 days after cardiac transplantation hemodynamics at rest were normalized. Left ventricular ejection fraction at rest and during exercise was within normal ranges for all patients except one. During symptom-limited bicycle exercise (121 +/- 35 Watt), pulmonary capillary wedge pressure (PCP) and right atrial pressure (RAP) increased to unphysiological high levels (PCP: 8.2 +/- 2.7 mmHg at rest, 19.1 +/- 4.9 mmHg at exercise; RAP: 4.1 +/- 2.3 mmHg at rest, 12.1 +/- 3.9 mmHg at exercise), whereas cardiac index was elevated to a normal level (3.6 l/min.m2 at rest; 6.9 l/min.m2 at exercise). Increase in heart rate, however, was subnormal (from 90 +/- 13/min at rest to 122 +/- 15/min at exercise). To examine the influence of heart rate on hemodynamics, in 8 patients with normal tricuspid valve function, heart rate was gradually increased by atrial stimulation during continuous exercise; PCP maximally could be reduced from 19.1 +/- 4 mmHg to 10.8 +/- 2.7 mmHg (p less than 0.01) at an optimum heart rate of 139 +/- 9/min. Reduction of RAP was by far less pronounced and normalization could not be achieved (from 12.2 +/- 3.7 mmHg to 9.5 +/- 3.4 mmHg, p less than 0.01), suggesting an impaired right ventricular function. By atrial stimulation stroke volume was reduced from 109.8 +/- 17.7 ml to 91.8 +/- 14.2 ml (p less than 0.01). These results indicate that, at exercise, the denervated transplanted heart, to a large extent, increases cardiac output by means of the Frank-Starling mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Output↗
PubMed1988

[Rupture of the ventricular septum following posterior wall infarction: echo- and Doppler echocardiography diagnosis with pressure determination].

In the postinfarct ventricular septal rupture, an early surgical intervention improves prognosis. A rapid and accurate diagnosis is necessary. A 56-year-old patient was admitted to the hospital with a Q-wave posterior myocardial infarction. Auscultation suggested a ventricular septal defect. Neither M-mode nor the two-dimensional echocardiography with apical four- chamber view could confirm the ventricular septal defect. Only the subcostal view showed a basal ventricular septal defect, which was sometimes covered by the septal leaflet of the tricuspid valve. With the continuous wave Doppler, a left-to-right shunt on the ventricular septum could be registered and the pressure in the right ventricle could be measured. Catheterization confirmed the diagnosis of a basal ventricular septal defect with the associated pressure characteristic. The basal ventricular septal defect was successfully closed with a patch. The high accuracy of the continuous-wave Doppler, which is superior to M-mode and two-dimensional echocardiography, was confirmed by this report. Pressure measurement in the right ventricle by continuous wave Doppler also provides a non-invasive diagnostic method that can be used at the bedside.

Blood Flow Velocity↗
PubMed1987

[Slow increase in the size of the left atrium with atrial fibrillation--a congenital pericardial defect or aneurysm of the left atrium?].

Gradual left atrial enlargement and development of atrial fibrillation--congenital pericardial defect or left atrial aneurysm? Left atrial aneurysms are rare. Whether or not a pericardial defect is associated can be ascertained by a diagnostic left-sided pneumothorax with air entering the pericardial cavity, although a negative finding does not necessarily rule out the presence of a defect. Cardiac surgery (aneurysmectomy) is advisable if the patient develops significant symptoms or if there is a progressive increase in atrial size. A case is presented with progressively increasing left atrial aneurysm and the development of atrial fibrillation. Although a pericardial defect was postulated (from echocardiogram, MR, CT, angiogram) the pericardium was found to be intact at surgery.

Atrial Fibrillation↗
PubMed1985

[Reconstruction of the right ventricular outflow tract with xenogeneic or allogeneic valve-bearing conduits].

From April 1974 to February 1985 131 patients were operated for reconstruction of the right ventricular outflow tract with 147 valve-carrying conduits. 79 were xenogenic (XC) and 68 sterilized and preserved allogenic (AC) conduits between right heart and lung in the following heart defects: DOLV 2, DORV 6, Fallot 24, pulmonary atresia 33, TGA, VSD and pulmonic stenosis 20, single ventricle 7, tricuspid atresia 10 and truncus arteriosus 41. Mean age was 6.6 and 5.2 years of age. The operative mortality was 13.6%. 11 more patients died later--2.0 months to 2.5 years postoperatively. 16 patients were reoperated (change of the conduit). The observation time is now 5 years in the XC-group and 1.4 years in the AC series. Up to now no dysfunction in the AC-group could be seen.

Adolescent↗