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Biomedical subjects

G Ziemer

Publications and source records attributed to G Ziemer.

At least 91 records · Page 5Linked to original sources
PubMed1993

Coarctation of the pulmonary artery in neonates. Prevalence, diagnosis, and surgical treatment.

Stenosis or discontinuity of the central pulmonary artery at its bifurcation is often found in patients with congenital heart disease with intracardiac obstruction of the right side. The prevalence of this disease in autopsy cases is about 30%. The clinical prevalence has not been established yet because early diagnosis of this lesion is easily missed. Embryology suggests an etiologic similarity between coarctation of the aorta and this type of stenosis: both are caused by invasion of ductal tissue into the respective great artery. Therefore, the term coarctation of the pulmonary artery is appropriate. To recognize or exclude coarctation of the pulmonary artery, we examined left ventricular angiograms, aortograms, or both in the hepato-clavicular++ view in 25 consecutive neonates with severe arterial hypoxemia caused by right ventricular outflow tract obstruction. The prevalence of coarctation of the pulmonary artery was 36% (9/25). Fifteen neonates had two ventricles, and the other 10 had different types of univentricular heart. In eight cases no patent ductus arteriosus was found, and in none of these cases was coarctation of the pulmonary artery present. Conversely, in 9 of 17 neonates with a patent ductus arteriosus, coarctation of the pulmonary artery of different degree was demonstrated, even during prostaglandin E1 infusion in 7 neonates. With regard to surgical procedures, ductal tissue in the pulmonary artery wall should be completely removed. The aim is to establish adequate blood flow to both right and left pulmonary arteries. In this way unilateral hypoplasia of the arterial tree and consecutive growth of tortuous bronchial collaterals is prevented.

Abnormalities, Multiple↗
PubMed1993

[Atrial arrhythmias after modified Fontane operation: effect of preoperative hemodynamics and the kind of operation (atriopulmonary vs. total cavopulmonary anastomosis)].

UNLABELLED: Between October 1986 and March 1992, occurrence of supraventricular tachycardia and sinus node dysfunction was investigated pre- and postoperatively by serial ECG and Holter monitors in 63 consecutive patients with univentricular circulation after modified Fontan operation (total cavopulmonary connection 39 patients, atriopulmonary connection 24 patients). Mean age at operation was 7.2 (0.1-20.3) years. Of the 63 patients, 14 (22%) had early (< 14 d) supraventricular tachycardia or sinus node dysfunction, which was not related to the type of operation. None of nine patients with a preoperative mean right atrial pressure < or = 2.5 mm Hg had early supraventricular tachycardia or sinus node dysfunction, in contrast to 16/54 patients (30%) with a preoperative mean right atrial pressure > or = 2.5 mm Hg. 6/63 patients died during the early (< 14 d) postoperative period. In only one child death was related to a dysrhythmia (junctional ectopic tachycardia). During a mean follow-up of 2.5 years, 12 patients (21%) had late supraventricular tachycardia or sinus node dysfunction. Early supraventricular tachycardia/sinus node dysfunction was a predictor of late atrial dysrhythmias, as it occurred in eight of the surviving 14 patients with early dysrhythmias, in contrast to four children without early atrial dysrhythmias (p < 0.001). After creation of an atriopulmonary connection, 10/22 patients (45%) had late supraventricular tachycardia/sinus node dysfunction, but only 2/35 patients (6%) with a total cavopulmonary connection had late atrial dysrhythmias (p < 0.001). CONCLUSIONS: Early atrial dysrhythmias after the Fontan operation were related to preoperative hemodynamics. Early supraventricular tachycardia/sinus node dysfunction and the atriopulmonary type of Fontan connection were significant risk factors for late atrial dysrhythmias.

Adolescent↗
PubMed1993

[Therapy of postoperative ectopic junctional tachycardia by surface hypothermia].

Postoperative junctional ectopic tachycardia is associated with a poor prognosis in patients after open-heart surgery. This dysrhythmia has been shown to be resistant to medical treatment as well as to epicardial pacing and external cardioversion. Successful therapy with surface hypothermia in an infant with junctional ectopic tachycardia (ventricular rate 210-230 bpm) after repair of tetralogy of Fallot is presented. Hypothermia (rectal temperature 32-34 degrees C) was effective in decreasing the ventricular rate of the dysrhythmia (< 170 bpm). After spontaneous cessation of the tachycardia, sinus rhythm resumed, resulting in stable hemodynamics.

Combined Modality Therapy↗
PubMed1992

Thoracic organ transplantation in the paediatric age group. The Hannover experience.

Growing experience in terms of immunosuppression, recipient and donor selection as well as organ preservation has established thoracic organ transplantation as a therapeutic option for many children with end-stage cardiopulmonary diseases. While dilated cardiomyopathy and isolated myocardial failure represent the main indications for cardiac transplantation, replacement of the lungs or heart and lungs is necessitated in cystic fibrosis, primary and secondary pulmonary hypertension as well as some types of complex congenital heart defects involving the pulmonary arteries. We have performed a total of 20 heart, 4 heart-lung, 2 single lung and 1 double lung transplantation in the paediatric group up to 17 years of age. While with respect to the limited experience worldwide, early mortality after lung and heart-lung transplantation is still high (50%), long-term results in isolated cardiac transplantation using triple drug immunosuppression are excellent (79% survival after 6 years) without major impairment of renal function, arterial blood pressure, growth development and physical rehabilitation as well as social reintegration. Freedom from graft atherosclerosis of the allografted heart is documented over a 5 year follow up, while no data are available on the incidence of obliterative bronchiolitis after lung transplantation in the paediatric group. Despite only limited evidence of long-term dysfunction, diagnosis and prevention of chronic rejection should be given utmost attention to allow for a normal life span in this younger age group.

Adolescent↗
PubMed1992

Pulmonary artery sling with tracheal stenosis: primary one-stage repair in infancy.

Pulmonary artery sling is often associated with tracheal stenosis. In many cases repair of the vascular anomaly alone does not relieve dyspnea. Primary one-stage repair with long segment tracheal resection (2.4 cm) and relocation of the left pulmonary artery using cardiopulmonary bypass and deep hypothermic circulatory arrest is described in a 6.5-month-old girl weighing 6.5 kg. This technique resulted in normal ventilation and pulmonary flow distribution.

Bronchi↗
PubMed1992

Staged chest closure in pediatric cardiac surgery preventing typical and atypical cardiac tamponade.

Chest closure after cardiac surgery occasionally results in cardiac compression leading to circulatory failure. In shunt-dependent circulation, the arterial oxygen saturation may decrease significantly due to the increase in pulmonary vascular resistance caused by chest closure. Temporary patch implantation with delayed sternal closure facilitates circulatory and/or pulmonary stabilization (temporary chest wall patch plasty, TCWPP). Between July 1986 and June 1991, 42 patients underwent staged chest closure (TCWPP) after open heart surgery for congenital lesions (4.9% of 854 patients). TCWPP was performed when either primary hemodynamic deterioration or an increase in cyanosis (palliative procedures only) followed by hemodynamic deterioration occurred during attempted or shortly after sternal closure. Overall mortality was 40.4% (17/42). It was 32.3% (11/34) when the patch was inserted primarily at the end of the operation. If the patch was inserted emergently 4-24 h postoperatively, mortality was 75% (6/8). Definite chest closure was performed from 4 h to 6 days (mean 72 h) postoperatively. In 2 patients closure had to be performed emergently (single ventricles); 7 patients died before chest closure. One mediastinal microbiology examination was positive. Deep sternal infection necessitating operative revision occurred in one other patient. In conclusion, TCWPP may considerably lower mortality of the illest patients after surgery for complex congenital heart disease. A timely decision as to the performance of staged chest closure is mandatory. This procedure rarely causes infection. We now apply this technique liberally, by cardio-mediastinal size judgement in over 30% of our TCWPP candidates even without a prior trial of primary closure.

Adolescent↗
PubMed1992

Partial "anomalous" hepatic venous connection associated with secundum atrial septal defect.

Postnatal connection of hepatic veins with the coronary sinus represents the rare persistence of a normal early embryonic development. A case is presented where this was found intraoperatively, associated with a secundum type atrial septal defect. Knowledge of this anatomic variation and its specific features may facilitate preoperative diagnosis, thereby preventing surprises in the operating room.

Adult↗
PubMed1992

Open-heart surgery in patients requiring chronic hemodialysis.

The management and outcome of open-heart surgery in 31 patients requiring chronic hemodialysis because of end-stage renal failure are reviewed. The reasons for surgery were coronary artery disease (20 cases), mitral valvulopathy (5, including 3 with tricuspid insufficiency), aortic valvulopathy (5, including 2 with coronary artery disease) and perforation of an aortic aneurysm into the left upper lung lobe. Surgery was elective in all but the last case. Apart from double venous cannulation to avoid potassium overload after cardioplegia, and hemofiltration in the extracorporeal circulation permitting removal of 1,500-2,000 ml fluid during bypass, procedure was routine. Postoperatively fluids were restricted and serum potassium levels were not allowed to exceed the known preoperative maximum. Four patients required catecholamine support for 3-10 hours. Thirty were weaned from the respirator after 8-41 (mean 16) hours. The one perioperative death was due to complications associated with post-bypass administration of protamine. Dialysis was restarted 20-69 (mean 32) hours postoperatively. With appropriate management of fluid balance and potassium, open-heart surgery in dialysis-dependent patients need not carry heightened risk.

Adult↗
PubMed1992

[Complex progressive palliation for univentricular circulation].

The type of palliative procedures (PP) for complex univentricular circulation (UC) changed significantly during the 80ies. Between 07/86 and 02/91 77 patients (pts) presented with UC to eventually undergo a modified Fontan-Kreutzer-type-operation (MFKTO). 33 pts had been previously palliated, 22 of whom were accepted for MFKTO as well as an additional 9 not palliated pts (group A: 31 pts; 20 PP). 11 previously palliated pts and 35 new pts required new palliations (group B: 46 pts; 89 PP), 34 of which resulted in 13 MFKTO. Prerequisites to be met for MFKTO are: undistorted PA-anatomy; absence of subaortic stenosis (SAS); Qp greater than 2.5 l/min/m2; PAP less than 20 mm Hg; Rp less than 3 Wood Units. All earlier PP in group A (31 BTS, 3 PAB, 2 PA-valvotomy/dil.) merely prolonged survival by only adjusting Qp. In group B PP comprise reconstruction of pulmonary arteries, aortic arch and isthmus as well as bypass or resection of SAS or atrial septectomy. Mortality for complex PP (group B) was 32.5% (15/46). 9 of these pts were neonates, 7 after modified Norwood procedures. In an attempt to plan a MFKTO for all pts presenting with UC (group B), complex PP was necessary. The high mortality is due to lesions in pts who would not have survived if only closed PP were applied.

Child↗
PubMed1991

Hyperacute rejection in heart allografts. Case studies.

Hyperacute rejection in orthotopic heart allografts is a rare event. In our material from a total collective of 524 heart-transplanted patients, we have observed two cases of hyperacute rejection, which are presented in this case report. Histopathologically, this entity is characterized above all by the following triad: pronounced edema, hemorrhages, and regressive changes up to necroses of myocytes. Besides the well-known risk factors, our report draws attention to two further factors possibly associated with an increased risk of hyperacute rejection: 1) repeated cardiac surgery prior to the transplantation, and 2) presence of identical viral genomes in recipient's and donor's heart.

Adult↗
PubMed1990

Coarctation of the aorta in complex congenital heart disease: simultaneous repair via sternotomy.

Coarctation of the aorta (CoA) is often associated with complex congenital heart disease. Patients with such a combination may not benefit from coarctectomy alone. Eight children who presented with complex malformations of the heart underwent simultaneous repair of CoA and intracardiac surgery via sternotomy. After extensive mobilization of the aortic arch, cardiopulmonary bypass was established. During the cooling phase for deep hypothermic circulatory arrest (six cases), a persistent temperature gradient between the upper and lower half of the body confirmed the significance of CoA. One child was operated upon in deep hypothermia with low flow and one underwent valve repair on cardiopulmonary bypass. Mobilization of the descending aorta enabled CoA resection and end-to-end anastomosis with a running absorbable suture. The average descending aortic cross-clamping time was 15 min. By this time, the patient had been cooled sufficiently for the intracardiac procedure. There were two operative deaths not related to coarctectomy. The remaining children showed no arm-to-leg pressure gradient. Five were discharged from hospital and one patient died late from septicaemia. In our hands, this technique has served to accomplish simultaneous relief of CoA and repair of the intracardiac lesion thus sparing critically ill infants the hazards of repeated procedures.

Aorta, Thoracic↗
PubMed1990

Distant organ procurement in clinical lung- and heart-lung transplantation. Cooling by extracorporeal circulation or hypothermic flush.

The scarcity of suitable donors for single lung and heart-lung transplantation calls for methods of medium-term pulmonary preservation to allow for distant organ procurement. At our institution, the first five grafts (four heart-lung, one single lung) were cooled by means of a transportable extracorporeal circulation unit, while the last eight grafts (four heart-lung, four single lung) were flush-perfused with modified cold Euro-Collins solution. The technique of extracorporated circulation included aortic and right atrial cannulation and cooling to 12 degrees-14 degrees C (rectal temperature) using a bubble oxygenator. Bypass times ranged between 41 and 52 min. Following excision, the organs were transported in ice-cold donor blood for ischemic times from 171 to 310 min. For cold flush preservation, simultaneous coronary (cold St. Thomas's solution) and pulmonary artery perfusion (Euro-Collins solution, 50 ml/kg over 4 min) were initiated simultaneously. The organs were transported in cold Euro-Collins solution for ischemic times of 175 to 270 min. In heart-lung transplantations the first postoperative arterial PO2 upon arrival at the intensive care unit was 120 +/- 38 Torr in the extracorporeal circulation and 140 +/- 38 Torr in the Euro-Collins solution group. Six of eight patients were extubated within 48 h after cardiopulmonary grafting. We conclude that pulmonary function following heart-lung or single lung preservation with simple hypothermic flush is as good or better than that following extracorporeal circulation. Since distant organ retrieval is much more convenient without the latter, preservation using Euro-Collins solution is preferred.

Adolescent↗
PubMed1990

Heart transplantation: intraoperative management, postoperative therapy and complications.

Currently, heart transplantation (HTX) is performed as an orthotopic cardiac replacement according to the technique of Lower and Shumway in over 95% of the cases with good results. Survival after heterotopic HTX, by contrast, remain poor (one year survival: 50%). Postoperative therapy compiles primarily prophylactic measures to prevent complications, especially organ rejection and infections. Immunosuppressive prophylaxis generally includes a triple drug therapy consisting of cyclosporin, prednisolone, and azathioprine for maintenance therapy. Initially there is often an additional application of poly- or monoclonal antibodies. The prime measure to prevent infection during the initial hospital stay will be reversed isolation of the recipient. Initial antibiotic prophylaxis resembles that of conservative cardiac surgery, but in addition antiviral and antifungal prophylaxis is applied. The most common postoperative complication following HTX is cardiac rejection, which is detected by routine endomyocardial biopsies. At our institution the incidence of rejection decreases from 3.07 episodes per patient in the first 3 months to 1.97 episodes during the last 6 months of the first year after HTX. In general, acute rejection is treated by methylprednisolone (3 x 500 mg/day) or anti-T-cell-antibodies. Infections often occur following intervals of increased immunosuppression, usually early postoperatively and following therapy of acute rejections. Often, invasive diagnostic measures have to be taken rapidly in order to allow for specific therapy (antibiotics, antimycotic treatment, virostatic agents). Close follow-up of the heart transplant recipient and rapid therapy of possible postoperative complications enable the current one-year survival rates of 80% or more.

Anesthesia↗
PubMed1990

[Simplified surgical procedure for closure of the ductus arteriosus in premature infants].

The necessity of closing a hemodynamically significant patent ductus arteriosus (PDA) in a premature neonate is unequivocal. Until 12/86 the PDA was disected and ligated and a chest tube was inserted (127 pts.) Since 1/87 45 pts. (weight less than 1500 g) underwent PDA-closure using a metal-clip and no chest tube. Simplified surgical technique in closure of PDA in the premature neonate has led to a marked reduction of operating time (mean from 36 to 18 min) and has decreased the incidence of perioperative complications.

Birth Weight↗
PubMed1988

A new sealant for knitted Dacron prostheses: minimally cross-linked gelatin.

There has been a resurgence of interest in the concept of presealing high-porosity knitted Dacron prostheses with an absorbable biologic material. Such a material should provide reliable porosity control, preferably reducing water porosity from 2000 ml/cm2/min to less than 50 ml/cm2/min. It should not interfere with the fibrous and vascular ingrowth that securely anchors the developing pseudointima. In previous studies, we have examined fibrin glue and two forms of aldehyde cross-linked insoluble collagen used as Dacron sealants. We concluded that delayed resorption of the sealant as seen with glutaraldehyde cross-linked insoluble collagen results in undesirable healing characteristics, particularly lack of adhesion between pseudointima and the luminal surface of a prosthesis. This study examines a new sealant. Soluble collagen (gelatin) is treated to reduce the number of free amino groups available for aldehyde cross-linking. It is then weakly cross-linked with an aldehyde mixture and applied to a knitted Dacron prosthesis. Water porosity studies have confirmed satisfactory porosity control. Both rat subcutaneous and canine circulatory implants for 6 months reveal relatively rapid and complete sealant resorption without undesirable modification of the normal healing process of knitted Dacron.

Animals↗
PubMed1988

Cryopreserved and fresh antibiotic-sterilized valved aortic homograft conduits in a long-term sheep model. Hemodynamic, angiographic, and histologic comparisons.

There is a paucity of clinical and experimental data regarding the fate of cryopreserved valve aortic homografts. Fifteen lambs (mean age 4 months) underwent insertion of a valved aortic homograft between the right ventricle and pulmonary artery. In eight animals, the homografts were treated with antibiotics for 48 hours followed by up to 4 days of 4 degrees C storage (group A). In the other seven animals, the homografts were treated with antibiotics and cryopreserved at -196 degrees C (group B). The 12 long-term survivors were catheterized at 6 weeks and 4 months after implantation, at which time three animals from each group were killed. The remaining six animals were catheterized and killed at 9 months. There was no significant difference in transconduit gradient (p = 0.67) or resistance indexed to weight (p = 0.81) between groups A and B. The mean increase in transconduit gradient for both groups between catheterization at 6 weeks and 4 months was 73%, and weight increased by 51%. Histologic analysis focusing particularly on valve leaflet architecture and changes in the aortic wall revealed greater differences between individual animals and according to duration of implantation than differences between groups A and B. However, focal intracuspal thrombus of unknown significance was seen only in animals from group B. Although conduit valve leaflets generally remained free of calcification, calcification was prominent within the conduit wall of all animals. In conclusion, cryopreservation does not appear to adversely affect leaflet integrity and conduit function in this accelerated animal model relative to fresh homografts. This is in contrast to past clinical experience with homografts treated by freeze-drying and irradiation.

Animals↗
PubMed1988

[Surgery of congenital heart defects in deep hypothermic cardiovascular arrest: postoperative renal function].

We investigated early postoperative renal function in 55 consecutive infants who underwent cardiac surgery in deep hypothermic circulatory arrest (DHCA). In 15 of these patients detailed studies of glomerular and tubular function of the kidneys were performed. Mean time of circulatory arrest at 20 degrees Celsius rectal temperature was 53 +/- 15 minutes. Acute renal failure was seen in four patients due to cardiogenic shock from which they died on the second and third postoperative day. Urine flow in the surviving 51 infants ranged from 120 to 150 ml/h/1.73 m2. The preoperative creatinine clearance was 50 +/- 23 ml/min/1.73 m2. Postoperatively, creatinine clearance was slightly decreased (42 +/- 16 ml/min/1.73 m2), but had completely recovered after 7 days. The renal transport of phosphate, glucose and uric acid remained unchanged. There was a marked increase in urinary excretion of protein, albumin, alpha-1-microglobin and N-acetyl-glucosaminidase which peaked 7 hours after the operation and then normalized. If sufficient surgical hemodynamics are provided postoperatively, there is only slight impairment of glomerular and tubular function, which demonstrates that DHCA has no negative effect on renal function.

Acute Kidney Injury↗