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Biomedical subjects

S Hagl

Publications and source records attributed to S Hagl.

At least 181 records · Page 10Linked to original sources

Heart transplantation: limitations and perspectives.

The intrinsic limitations of heart transplantation are the restricted availability of donated organs, patient selection, hospitalisation costs, and the limited capacity of cardiac surgery clinics. With a better understanding of organ transplantation and heart transplants in particular, both by the general public and the medical profession, improvements in the care of patients with terminal myocardial disorders seem to be possible with heart transplantation. The one year survival rate for heart transplants is 80%. The success of the treatment is determined by the hemodynamic capacity of the transplanted organ, security against rejection reactions, effects of cellular transplant reactions, and side effects of immunosuppression. Within defined limits heart transplantation is the best standardised method of treatment for terminal myocardial failure.

Adolescent↗

Floating pulmonary embolus: unusual cause of recurrent syncope.

A 69-year old woman was admitted because of recurrent syncopal episodes. In hospital, she had repeated attacks of near fainting or syncope when she was turned into the left decubitus position. Continuous arterial pressure monitoring revealed that severe hypotension initiated these events. Secondarily, the heart rate dropped markedly. The symptoms quickly reversed when the patient was turned back into the supine or right decubitus position. Angiography revealed a large, riding and partly floating pulmonary embolus that obstructed the pulmonary circulation to a variable degree, apparently influenced by the patient's body position. During subsequent emergency surgery the angiographic findings were confirmed. It appears that the severe hypotensive episodes were caused by intermittent high degree obstruction of the pulmonary circulation by the floating pulmonary embolus, a mechanism that, to our knowledge, has not previously been described as a cause of recurrent syncope.

Aged↗

[Heart transplantation: successful treatment of postoperative complications. Case report with 19 months' follow-up].

In March, 1981, a 37-year old patient underwent cardiac transplantation, the first to be performed in Germany since 1969. Subsequent to the successful procedure, the patient has now been followed for more than 19 months. The indication for the intervention was established on the basis of endstage coronary artery disease. The operation was performed according to the technique of Lower and Shumway. Immunosuppression, in the early postoperative phase, was carried out with antithymocyte globulin, azathioprine and corticosteroids with administration oriented on the T-lymphocyte and total leukocyte counts as well as analysis of myocardial biopsies. In the late postoperative course, dosage of immunosuppressive agents was based almost exclusively on biopsy findings. Within the course of immunosuppressive therapy for cardiac transplantation, in particular, initial experience was gained with the use of antithymocyte globulin which was given in dosages of up to 12 mg/kg daily. The antithymocyte globulin proved effective for more than six weeks postoperatively. The alterations in immunosuppressive treatment necessitated by two gastrointestinal complications (perforated gastric ulcer, perforation of the small intestine) enabled a comparative analysis of the results of therapy with cyclosporin A given orally, intravascularly and intravenously. The Patient continues to be maintained on a regimen of cyclosporin A and corticosteroids and his general condition is good. For future cardiac transplantations, in the early postoperative course, alternating treatment with antithymocyte globulin, azathioprine and corticosteroids, on the one hand, with cyclosporin A and corticosteroids, on the other hand, would seem meaningful both to minimize adverse reactions as well as to provide effective immunosuppression. The experience rendered would promise to facilitate management of patients after cardiac transplantation.

Adolescent↗

The effects of deep hypothermia and circulatory arrest on systemic metabolic state of infants undergoing corrective open heart surgery: a comparison of two methods.

Fortyone of 187 infants undergoing corrective surgery for their congenital cardiac lesions using profound hypothermic circulatory arrest were randomly selected for metabolic studies. Deep hypothermia of 21 to 22 degrees C core temperature was reached by two different techniques: 1. Perfusion cooling by extracorporeal circulation (ECC-C) 2. Surface cooling with ice bags combined with perfusion cooling (SC + ECC-C) After circulatory arrest (34.2 min. ECC-C v.s. 46.7 min. SC + ECC-C) bypass rewarming was used in both groups. The metabolic reaction to these interventions are described. No significant differences in acid base status in oxygen consumption, lactate concentration, serum electrolytes (K+, Na+, Ca++,Cl-) and serum enzyme activity (CPK, alpha-HBDH, LDH, SGOT, SGPT) could be demonstrated between the two groups of patients during the entire course of cooling, circulatory arrest and rewarming. The glucose concentration was significantly lower in the ECC-C group during the entire period of operation. Total cooling time was significantly shorter in the group without surface cooling. (ECC-C: 12 min, v.s. SC + ECC-C: 64 min). Since no favourable effects of the SC + ECC-C method on systemic metabolism could be demonstrated and operative results were similar we now prefer the time-saving ECC-C technique.

Acid-Base Equilibrium↗

Acute effects of aortocoronary bypass surgery on left ventricular function and regional myocardial mechanics: a clinical study.

The acute effects of myocardial revascularization on overall left ventricular performance and on myocardial segmental wall motion were assessed intraoperatively in 22 patients who had unstable (11 patients) or stable angina pectoris (11 patients). Segmental contraction patterns were evaluated using an ultrasonic transit-time method. In 9 patients with unstable angina pectoris, notable improvement in segmental wall motion was observed as the short-term response to coronary bypass grafting. Hypokinetic patterns were rendered normal after revascularization. Despite marked changes in segmental myocardial function, overall left ventricular performance was not altered notably. In contrast, reperfusion did not lead to acute effects on either segmental wall motion or total left ventricular function in patients with stable angina pectoris. The results indicate that aortocoronary bypass grafting may improve segmental wall motion in patients with unstable angina.

Adult↗

[Pacemaker therapy in infants (author's transl)].

Since April 1974 until January 1978 permanent pacemakers were implanted in 21 children. The patient age at the time of operation averaged 4.5 years; the youngest patient was 3 months old. Indications for pacemaker implantation were: congenital total a-v block (TAVB) (n = 4), sick syndrom (S-S-S) (n = 4), postoperative TAVB (n = 13). Cardiac failure was present in all patients despite optimal medical treatment. Pacemakers were implanted under general anesthesia and intubation. The stimulation electrodes were positioned by the transvenous route in 16 subjects and by direct fixation upon the ventricle and the atrium in 5 patients. 5 children obtained an atrial triggered, 14 patients R-inhibited demand pacemaker and 2 subjects an asynchronous pacemaker. After a mean observation time of 16.4 months mean pacemaker function is normal in 14 patients. 6 children died 1 to 33 months after implantation despite functioning pacemakers because of congestive heart failure. Pacemaker malfunction was observed in 4 patients. The type of malfunction induced: failure of the impulse generator (n = 2), dislodgement of the electrode (n = 2), threshold increase (n = 1). In 5 children generators were changed 9 to 36 months (m = 23 plus or minus 10) after implantation because of battery depletion. The use of the pacemakers in small children is connected with several specific problems: 1. Application of large generators is hazardous because of impending perforation and secondary infection. 2. Until now miniaturization of pacemakers decreases function time and therefore implies frequent surgical intervention. 3. Stretching and dislodgement of transvenous electrodes may occur due to growth of the child. 4. Threshold increase may limit the life-span of myocardial electrodes. 5. Physiological changes in natural frequency requires changes in stimulation rate. 6. To guarantee normal physical activity demand related adaptation of heart rate is necessary. Because of these reasons a pacemaker system for children should have the following criteria: low weight, small wolume, high energy capacity, atrial or programmable stimulation, a thin elastic perhaps coiled electrode.

Adolescent↗

[The effect of nitrates on the function of intact and ischemic myocardium (author's transl)].

The effects of Sodium Nitroprusside (NPN), of Isosorbidedinitrate (ISDN), and of a combined therapy with NPN and the intraaortic balloon pump (IABP) on left ventricular function and on local contraction patterns of normal and ischemic myocardial regions were studied. In acute experiments on 16 dogs the anterior descending branch of the left coronary artery was stenosed to produce a hypokinesia or dyskinesia of the anterior wall of the left ventricle. Regional myocardial function was assessed using the ultrasound transit time method. When the LV filling pressure was initially norman (LVedP 5.7 +/- 0.6mmHg) nitrate infusion (120 microgram/minn NPN: 800 microgram/min ISDN) resulted in an aggravation of the ischemic dysfunction. Conversely, with high initial filling pressure (LVedP 15.4 +/- 1.3MMHg) regional myocardial function in the ischemic area returned to normal under therapy. Additional application of the IABP further improved regional myocardial mechanics. It is concluded, that reduction of coronary perfusion pressure due to nitrate therapy becomes critical when coronary reserve is depleted. Compensation is however possible if ventricular wall stress can be reduced and thus the oxygen consumption and the extravascular component of coronary resistance are decreased. Only when the initial filling pressure is high these conditions are met.

Animals↗

[Hemodynamic studies after the implantation of Hancock-heart valves (author's transl)].

Velocity profile, pressure gradient across the valve and blood flow have been measured in 10 patients after the implantation of bioprostheses of the sizes 27 and 29 millimeters in aortic position. According to these hemodynamic measurements the use of bioprostheses for the aortic valve replacement is recommendable. The low flow velocities in the area of the muscle containing valve cusp did not effect a detectable stenosis intraoperatively under the conditions of rest. The hemodynamic data showed no differences between the Hancock-Zuhdi and the Edwards-Carpentier bioprostheses. Despite of good hemodynamic conditions and a low risk of thromboembolic complications after the aortic valve replacement with bioprostheses reservation is recommended to its clinical use until the long term mechanical stability (more than 6 years) of the biological heart valve prosthesis has been secured.

Adolescent↗

[Direct measurement of papillary muscle dynamics in the intact canine left ventricle during acute coronary occlusion (author's transl)].

UNLABELLED: The functions of the normal and ischemic papillary muscle in the intact canine heart were studied using an ultrasonic transit time method. Miniaturized piezoelectric crystals (1.5-2 mm 0) were implanted during extracorporeal circulation into the root and tip of the anterior and posterior papillary muscle of the left ventricle. RESULTS: 1. Phasic changes of left ventricular geometry during the heart cycle determine the dynamic pattern of papillary muscle movements. 2. The amplitude and velocity of papillary muscle length is directly related to those of myocardial wall segments. 3. Experimental ischemia induces total dysfunction of the papillary muscle within seconds. 4. Despite total muscle dysfunction no mitral insufficiency occured.

Animals↗

[Instantaneous blood flow velocity profiles before and after aortic valve replacement (author's transl)].

In 17 patients the instantaneous velocity profile was recorded before and after aortic valve replacement (Starr-Edwards, Björk-Shiley, Lillehei-Kaster). A single gated pulsed Doppler Ultrasonic flownmeter was used for analysis. Distal of these valves a flat flow profile was recorded showing high velocity gradients near the walls. As a main cause of this, numerous eddies and turbulent flow have been suggested. Downstream of a Starr valve a flat profile appears with a slowing down of forward flow just behind the ball. The disk valves Lillehei-Kaster and Björk-Shiley demonstrated a higher flow velocity in direction to the larger opening. The "in vivo" studies have been supported by "in vitro" measurements. The highest flow velocities were above 100 cm/sec and thus, according to Reynolds definition, in the turbulent range. The turbulent flow produces a washing effect, which is emphasized during the cardiac cycle. The importance of these data can be discussed by clinical results only.

Aorta↗

[Ultrasound transit-time method for evaluation of regional myocardial function (author's transl)].

The validity of an ultrasound transit-time method for defining local function was evaluated under experimental conditions in the anaesthetized open chest dog. Miniaturized piezoelectric crystals (1,5-2 mm phi) functioning as emitters and receivers were inserted into different depths of the myocardium to study the contraction patterns of defined muscle segments in different muscle layers and the dynamic changes of left ventricular wall thickness during the heart cycle. Changes in myocardial function were induced by coronary stenosis or occlusion and by the application of drugs. This method was shown to be a sensible and reliable tool for the evaluation of local myocardial function.

Animals↗