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Biomedical subjects

G Ziemer

Publications and source records attributed to G Ziemer.

At least 73 records · Page 4Linked to original sources
PubMed1998

Abdominal aortic aneurysms: treatment with juxtarenal placement of covered stent-grafts.

PURPOSE: To determine the technical feasibility and clinical outcome of juxtarenal placement of covered stent-grafts for endovascular treatment of abdominal aortic aneurysms with a proximal neck less than 15 mm long. MATERIALS AND METHODS: In seven patients, abdominal aortic aneurysms with infrarenal necks 3-14 mm long were excluded with juxtarenal implantation of polyester-nitinol coknit stent-grafts. The proximal uncovered portion of the stent-graft (length, 12 mm) was placed across one or both orifices of the renal arteries. Seven patients underwent standard infrarenal stent-graft placement. Clinical outcome in all 14 patients was determined with computed tomography (CT) and laboratory values and also with captopril renography in the patients who underwent juxtarenal placement. The mean follow-up was 10.1 months. RESULTS: Findings from serial follow-up CT and laboratory analysis performed in all patients and captopril renography performed in five of the patients who underwent juxtarenal stent-graft placement did not reveal impaired renal function or perfusion. CONCLUSION: Successful exclusion of abdominal aortic aneurysms located closer than 15 mm to the orifices of the renal arteries is possible with juxtarenal placement of the uncovered portion of the stent in the abdominal portion of the aorta.

Aged↗
PubMed1997

[Tricuspid valvulectomy in antibiotic-refractory right-heart endocarditis].

HISTORY AND CLINICAL FINDINGS: A 19-year-old man, known to be addicted to intravenous heroin, was admitted because of respiratory failure with a septic fever up to 40.0 degrees C. An abscess at the site of intravenously heroin injection on the right arm had been previously opened. At examination he was pale and his general condition was poor. There were numerous puncture sites over lower arm veins, some of them thrombosed. There were no signs of septic emboli to the skin and to visible mucosae. The spleen was not palpable. INVESTIGATIONS: There was leucocytosis with shift to the left, thrombocytopenia (54,000/microliter), anaemia (haemoglobin 7.9 g/dl) and markedly raised C-reactive protein (202 mg/dl). Blood culture grew Staphylococcus aureus. Transthoracic and transoesophageal echocardiography revealed a large vegetation on the tricuspid valve, confirming infectious endocarditis involving the tricuspid valve. Chest radiogram showed an infiltrate and pleural effusion of the left lung. TREATMENT AND COURSE: Infectious emboli to the lung necessitated artificial ventilation. The septic process could not be controlled by antibiotics. The whole of the tricuspid valve was therefore removed, followed by high doses of antibiotics (vancomycine, gentamicine, rifampicine). This successfully controlled the infection and a postoperative sacroileitis. Postoperative echocardiography revealed severe tricuspid regurgitation with marked enlargement of the right ventricle, paradoxical movement of the interventricular septum and a dilated inferior vena cava. 7 months postoperatively there were no clinical signs of severe right heart failure. CONCLUSION: Removal of the tricuspid valve without valve replacement can be successfully undertaken to control the infection in intravenously heroin addicts in whom the valve has been destroyed by infectious endocarditis.

Acute Disease↗
PubMed1997

[Total cavopulmonary anastomosis for definitive palliation of complex univentricular cardiovascular systems--potential preoperative risk factors].

The modified Fontan operation for definitive palliation has been performed in an increasing number of patients with various forms of a functionally univentricular heart. To eliminate the influence of different surgical techniques only patients after total cavopulmonary anastomosis (TCPA) were included in this retrospective analysis of preoperative risk factors. The age at operation in 72 patients varied from 7 to 219 months (median 54 months); 29 patients had been younger than 4 years. Forty-nine patients presented with a complex form of a functionally univentricular heart; associated systemic- or pulmonary venous anomalies were found in 22 patients, AV valve abnormalities in 42 patients with AV valve incompetence in 21 patients. Preoperative hemodynamic data revealed an elevated mean pulmonary artery pressure (> 15 mm Hg), increased pulmonary arteriolar resistance (> 3 U.m2) or end-diastolic ventricular pressure (> 12 mm Hg) in 23 patients. The overall mortality was 9.7% (7/72 patients). Variables with significant influence on postoperative mortality were associated systemic- and pulmonary venous anomalies. AV-valve incompetence and prolonged cardio-pulmonary bypass time. Age at operation, preoperative pulmonary arteriolar resistance, systemic- and pulmonary blood flow did not influence postoperative mortality. Even in patients with a complex form of a univentricular heart with associated anomalies and borderline preoperative hemodynamics TCPA can be performed with an acceptable risk.

Adolescent↗
PubMed1997

Anaphylactic shock after aprotinin reexposure: time course of aprotinin-specific antibodies.

We report a case of severe anaphylactic shock during a cardiac operation that occurred as a consequence of aprotinin readministration in the presence of preformed aprotinin-specific antibodies. Both immunoglobulin G (3 hours) and immunoglobulin E (5 minutes) antibody levels dropped early after the clinical event. Despite their possibly limited clinical significance, we still recommend the conductance of specific antibody screening tests before readministration of aprotinin.

Aged↗
PubMed1997

Single-incision and single-element array electrode to lower the defibrillation threshold.

Occasional patients have excessive defibrillation energy requirements despite appropriate transvenous defibrillation lead position and the use of biphasic shocks. A single-element subcutaneous array electrode was implanted in 2 patients with a high defibrillation threshold. The array electrode was implanted through the same infraclavicular incision that was used for implantation of the transvenous lead. The defibrillation threshold decreased from 30 J to 15 J and from 24 J to 9 J with the subcutaneous array electrode.

Cardiomyopathy, Dilated↗
PubMed1997

Extraanatomic thoracic aortic bypass grafts: indications, techniques, and results.

OBJECTIVE: Even in the age of extensive aortic replacement special circumstances may warrant the insertion of extraanatomic thoracic aortic bypass grafts. Our experience with 17 patients is analyzed. METHODS: Between 1988 and 1994, ten female and seven male patients (mean age 37.5 years, range 9-69 years) were treated for the following indications: (1) complex CoA (n = 5); (2) reoperation for CoA (n = 6); (3) extensive aortic occlusive disease (n = 4); and (4) complicated aneurysm (n = 2). Routing of the grafts was: ascending-descending aorta (8); ascending-abdominal aorta (4); left subdavian artery- descending aorta (2); descending-descending aorta (2); and descending-abdominal aorta (1). Eight procedures were reoperations. In four patients concomitant cardiac operations were performed: one aortic valve replacement, one patch plasty of the LCA, and two composite graft replacements of aortic valve and ascending aorta, one of them with CABG. RESULTS: Three early deaths occurred. two after emergency operation in thoracic aneurysm under dire conditions (one perforation, one infection), one after ascending-abdominal aortic grafting with multiple branch revascularization. The underlying pathology was relieved successfully in all 14 survivors. In the two patients with concomitant aortic valve and isthmic stenosis, critical anterior motion of the mitral valve, presumably because of the massive afterload reduction of the left ventricle, complicated the perioperative course. One patient was reoperated because of aneurysm 4 years after descending-descending aortic grafting for complex CoA with poststenotic dilatation. CONCLUSIONS: In complex aortic coarctation or hypoplasia extraanatomic bypass grafts are expedient and effective procedures, especially for reoperation. Their use in the treatment of aneurysmal lesions remains an exception.

Adolescent↗
PubMed1997

Postischemic synthesis of high energy phosphates in isolated porcine hearts during reperfusion with 11 or 25 degrees C hypothermic perfluorocarbon emulsion FC 43. A 31P magnetic resonance spectroscopy study.

OBJECTIVE: One aim of coronary reperfusion after myocardial ischemia is to restore the myocardial content of high energy phosphates. The superiority of the artificial oxygen carrier perfluorocarbon emulsion FC43 over blood solution is known, therefore, in this paper we examined the temperature-dependence of this substance. METHOD: The changes of the high energy phosphates phosphocreatine (PCr) and inorganic phosphate (Pi) were documented in 29 isolated pig hearts, employing a 4.7 Tesla magnetic-resonance-spectroscope (MRS). After 15 min warm ischemia, reperfusion with warm blood and a cardioplegic ischemia period of 45 min, these hearts were reperfused with either 11 or 25 degrees C hypothermic oxygenated perfluorocarbon emulsion FC43, both under continuous spectroscopy. MRS is able to directly measure PCr as well as Pi. Their relation expresses the state of myocardial energy stores. RESULTS: Reperfusion with 11 degrees C hypothermic FC43 (n = 14) caused an increase of the relation PCr to Pi by a factor of 9, compared to an increase by a factor of 4 with 25 degrees C emulsion (n = 15) (P < 0.05). During 80 min of reperfusion with 11 degrees C cold FC43 emulsion the average flow rate was 90 +/- 12 and 96 +/- 11 ml/min during reperfusion with 25 degrees C hypothermic FC43 emulsion. Both rates fell only slightly in the course of time. CONCLUSION: We conclude that reperfusion with 11 degrees C hypothermic oxygenated FC43 in isolated ischemic porcine hearts leads to a clear increase of the index PCr/Pi compared with reperfusion at 25 degrees C. The correlation between the synthesis of myocardial high energy phosphates with postcardioplegic ventricular function is questionable. If further studies will show an improvement of myocardial function after perfusion with hypothermic oxygenated perfluorocarbon emulsion FC43, this solution may find clinical application in the storage of explanted human hearts for transplantation, during transportation to the recipient.

Animals↗
PubMed1996

Isolated aortic coarctation in neonates and infants: results of resection and end-to-end anastomosis.

BACKGROUND: Operative resection is the treatment of choice for native aortic coarctation in most institutions. The ideal timing for elective repair is still a matter of debate. This study evaluated one institution's results with resection and end-to-end anastomosis in the first year of life. METHODS: Between January 1987 and December 1993, 46 neonates and infants with functionally isolated aortic coarctation underwent operative resection and end-to-end anastomosis. For the patients included in the study, all hospital records, catheterization data, and operative protocols were evaluated for retrospective analysis. To obtain valid follow-up information, all patients were systematically seen on an outpatient basis during 1994. RESULTS: After a mean follow-up of 49 +/- 24 months (range, 13 to 95 months), recoarctation (arm-leg blood pressure gradient > 20 mm Hg) occurred in 5 of 26 patients with neonatal operations (19%) and in 1 of 20 patients with operations in infancy (5%, p = not significant). Four of these 6 children with recoarctation needed reintervention. The other 2 patients had only mild recoarctation (gradients of 22 and 30 mm Hg, respectively) and were not treated. In all 6 patients, recoarctation was diagnosed within the first 6 months postoperatively. During the whole follow-up period, right arm systolic blood pressures slightly above the 90th percentile of normal developed in 11 of the patients (24%) (7 in the group with neonatal operation and 4 after operation in infancy; p = not significant). CONCLUSIONS: Resection with end-to-end anastomosis was shown to be an adequate therapeutic strategy for isolated aortic coarctation in neonates and infants. The results indicate that already beyond the neonatal age, there is a relatively low incidence of recoarctation.

Anastomosis, Surgical↗
PubMed1996

Modified Fontan operation in functionally univentricular hearts: preoperative risk factors and intermediate results.

BACKGROUND: The modified Fontan operation has been proposed as definitive palliation for an increasing variety of hearts with complex univentricular anatomy. To eliminate the influence of different surgical strategies, only patients undergoing total cavopulmonary anastomosis were included in this retrospective study. METHODS: Seventy-two patients had been operated on at ages ranging from 7 to 219 months, with 29 patients younger than 4 years. Twenty-three patients had mean pulmonary artery pressures higher than 15 mm Hg, elevated pulmonary arteriolar resistances (> 3 U.m2), or elevated end-diastolic ventricular pressure (> 12 mm Hg). Associated systemic or pulmonary venous anomalies were present in 22 patients (30%), and atrioventricular valve incompetence was present in 21 patients (29%). RESULTS: The overall mortality rate was 9.7% (7/72). Variables with significant effects on postoperative mortality were associated systemic or pulmonary venous anomalies, atrioventricular valve incompetence, mean pulmonary artery pressure greater than 15 mm Hg, and prolonged cardiopulmonary bypass time. Postoperative morbidity resulted mainly from atrial arrhythmia (20%). Clinical signs of protein-losing enteropathy or atrial thrombi were rare (3% and 6%, respectively). Postoperative hemodynamic data from 48 surviving patients (74%) revealed a mean transpulmonary gradient of 6.3 mm Hg, systemic venous pressure greater than 12 mm Hg in only 10 patients, and cardiac index less than 3 L.min-1.m-2 in 18 patients. CONCLUSION: In a high proportion of hearts with complex univentricular anatomy, associated anomalies, and borderline hemodynamics, the Fontan operation can be performed as a total cavopulmonary anastomosis with acceptable intermediate postoperative morbidity and hemodynamic results.

Adolescent↗
PubMed1996

Myocardial protection in chronic volume-overload hypertrophy of immature rat hearts.

OBJECTIVE: The benefit of cardioplegic cardiac arrest for protection of the immature myocardium is controversial. We therefore investigated the efficacy of (1) topical hypothermia alone (2) slow cooling by coronary perfusion hypothermia and (3) cardioplegic cardiac arrest plus topical cooling for protection of isolated immature rat hearts (age: 28 days). METHODS: The isolated perfused rat heart model was used. Hearts were subjected to 8 h of global ischemia at 10 degrees C. The study was conducted after clinically relevant conditions of volume-overload myocardial hypertrophy had been established non-invasively by lifelong feeding of a diet low in iron. Parameters of left ventricular function, endothelial function, the metabolic status and myocardial injury were measured. RESULTS: Topical hypothermia provided superior protection of hypertrophied hearts with recovery of maximum developed left ventricular pressure and rate of pressure rise at 41.2% +/- 22.3% and 34.5% +/- 20.7% (mean +/- standard deviation) of preischemic values (P < 0.05 versus slow cooling and versus cardioplegia plus topical hypothermia). The same pattern of recovery was observed among control hearts. The recovery of endothelial function following protection by topical hypothermia alone measured 55% +/- 41% in hypertrophied hearts and 62% +/- 37% in control hearts, but was not recordable in all other groups. In hypertrophied hearts post-ischemic myocardial high energy content was significantly improved with topical hypothermia alone for protection when compared to the other methods. Creatine kinase leakage during reperfusion did not differ significantly among the experimental groups. CONCLUSION: Rapid cooling by topical hypothermia along provides superior protection of hypertrophied- and non-hypertrophied-immature rat hearts to additional slow pre-arrest cooling. Use of St. Thomas' Hospital cardioplegic solution No.2 (STS 2) does not improve protection, and even hinders functional recovery in hypertrophied immature hearts. Endothelial injury caused by cold asanguinous perfusates, including cardioplegia, interferes with the recovery of vascular function, which in turn, may limit mechanical function.

Age Factors↗
PubMed1995

Protection of the chronic hypoxic immature rat heart during global ischemia.

The benefit of cardioplegic cardiac arrest for the protection of immature myocardium is controversial. We therefore investigated the efficacy of (1) topical hypothermia alone, (2) slow cooling by coronary perfusion hypothermia, and (3) cardioplegic cardiac arrest for the protection of isolated immature rats hearts (28 days) during 8 hours of global ischemia at 10 degrees C. The study was conducted in hearts from rats that were kept hypoxemic by lifelong exposure to simulated high altitude. Left ventricular function, endothelial function, the metabolic status, and the extent of myocardial injury were all assessed. Topical hypothermia provided superior protection in hypoxic hearts, with recovery of the maximum developed left ventricular pressure by 70.6% +/- 18.0% (mean +/- standard deviation) of its preischemic value (p < 0.01 versus slow cooling and versus cardioplegic protection). The same pattern of recovery was observed among control hearts. The degree of recovery of endothelial function after sole topical hypothermia measured 54% +/- 36% in hypoxic hearts and 62% +/- 37% in control hearts, but was not recordable in any of the other groups. Creatine kinase leakage and the myocardial high-energy content did not differ significantly among any of the groups. Rapid cooling by topical hypothermia alone provides superior protection in chronic hypoxic, immature rat hearts versus the protection conferred by slow cooling. St. Thomas' Hospital cardioplegic solution II does not afford additional protection. Endothelial injury caused by cold asanguineous perfusates, including cardioplegia, interferes with the recovery of vascular function, which, in turn, may limit mechanical function.

Adenosine Triphosphate↗
PubMed1995

Successful management of junctional tachycardia by hypothermia after cardiac operations in infants.

BACKGROUND: Junctional ectopic tachycardia is an early postoperative complication after intracardiac repair of congenital heart disease, especially in infants. Because of the high ventricular rate and the usually poor response to antiarrhythmic drugs, this condition is associated with a high morbidity and mortality. The purpose of this study was to assess the safety and efficacy of moderate body surface hypothermia in the treatment of postoperative junctional ectopic tachycardia in infants. METHODS: Six consecutive infants with postoperative junctional ectopic tachycardia (mean age at operation, 14 weeks) were treated with surface cooling. The decision to start treatment was based on the definition of a critical heart rate (180 to 200 beats/min) in the presence of junctional ectopic tachycardia diagnosed according to established criteria. Moderate hypothermia (rectal temperature between 32 degrees and 34 degrees C) was achieved by placing ice bags on the child's body surface. The patients were sedated, mechanically ventilated, and paralyzed. RESULTS: Mean interval between diagnosis of tachycardia and initiation of hypothermia was 4 hours. Rectal temperature was rapidly (within 1 hour) lowered to 32 degrees to 34 degrees C in all 6 patients. This significantly lowered the tachycardia rate from 219 +/- 27 beats/min to 165 +/- 25 beats/min (mean +/- standard deviation; p < 0.001). Three patients with signs of low cardiac output had restoration of stable hemodynamics once the tachycardia rate had been decreased by hypothermia. Cooling was maintained for a period of 24 to 88 hours (mean, 59 hours). No serious side effects were observed. CONCLUSIONS: Early institution of moderate hypothermia by body surface cooling was a safe and efficient measure to control ventricular rate in infants with postoperative junctional ectopic tachycardia.

Body Temperature↗
PubMed1995

Total cavopulmonary anastomosis in patients less than three years of age.

BACKGROUND: As young age at modified Fontan operation was thought to be a preoperative risk factor for poorer survival, we studied early and intermediate outcome in our young patient group. METHODS: Results in children less than 3 years of age (group I; n = 26; age range, 7 to 35 months) were compared with those in older patients (group II; n = 46; age range, 36 to 219 months). For both groups there was no significant difference with regard to preoperative pathology and hemodynamics. RESULTS: With an overall mortality of 9.7% (7/72) there was no significant difference for both groups. Group I (n = 23) and group II (n = 42) survivors did not differ with respect to early postoperative incidence of atrial dysrhythmias, duration and volume of pleural effusion, or incidence of reoperation. Results on intermediate follow-up (group I, 31 +/- 14 months; group II, 44 +/- 20 months) demonstrated a relatively low incidence of late atrial dysrhythmias (12.3%; 8/65). Late atrioventricular valve insufficiency was significantly more frequent in group I patients. CONCLUSIONS: With similar preoperative anatomic and hemodynamic parameters including 68% of patients with complex univentricular heart, total cavopulmonary anastomosis could be performed in patients less than 3 years of age with good clinical and hemodynamic results, as achieved in older patients.

Child, Preschool↗
PubMed1995

Modified Fontan procedure for Ebstein's anomaly of the tricuspid valve--an alternative surgical approach preserving Ebstein's anatomy.

In young patients with Ebstein's anomaly and symptoms of congestive heart failure or severe cyanosis tricuspid valve repair may be unsuccessful and prosthetic valve replacement is needed, which is associated with a high operative mortality. This report describes the implantation of a valved aortic homograft as a conduit between right atrium and pulmonary artery to at least postpone valve surgery in three symptomatic children (4.1, 8.3, and 10 years of age) with an arterial oxygen saturation of 75 to 82%. The intracardiac anatomy was left untouched except for closure of the associated secundum atrial septal defect. One patient with stable postoperative hemodynamics died of severe endobronchial bleeding on the 2nd postoperative day. Due to the increase of antegrade pulmonary blood flow via the conduit the arterial oxygen saturation rose to 92% in the two surviving patients. Postoperative hemodynamic evaluation revealed low right atrial and mean pulmonary artery pressures (12 mmHg). Pulsed Doppler ultrasound sampling of flow in the conduit demonstrated antegrade flow during atrial and ventricular systole. In symptomatic patients with severe malformation of the tricuspid valve a partial modified Fontan procedure offers a promising palliation avoiding tricuspid valve surgery in early childhood.

Aortic Valve↗
PubMed1994

[The value of myocardia protection in chronic hypoxic immature rat hearts].

This study examines the efficacy of three methods for myocardial protection during 8 hours of global ischema at 10 degrees C in immature (28 days) rat hearts subjected to lifelong hypoxia afforded by exposure to simulated high altitude. Hearts in group 1 were protected by rapid topical cooling alone, in group 2 by slow pre-arrest cooling with Krebs-Henseleit solution plus topical cooling and in group 3 by coronary perfusion with St. Thomas' Hospital cardioplegia No 2 (STS 2) plus topical cooling. Hearts in groups 4-6 served as controls without hypoxia and were protected accordingly. Parameters of myocardial function (left ventricular pressure, LVP), the metabolic status (myocardial concentration of ATP and creatine phosphate) and endothelial function (response to the vasodilator acetylcholine) were measured. Myocardial protection by rapid topical cooling alone resulted in equal--or significantly improved--postischemic recovery of LVP and endothelial function compared with slow pre-arrest cooling or additional protection with STS 2. The data advocate topical cooling for myocardial protection during surgical correction of cyanotic congenital cardiac disease in early infancy. In this age group, coronary perfusion with cold crystalloid solutions appears to aggravate ischemic endothelial injury.

Animals↗
PubMed1994

A new procedure for abdominal wound closure after pediatric liver transplantation: the "sandwich" technique.

Primary wound closure cannot always be achieved after pediatric liver transplantation (LTx). This may be due to lack of intraabdominal space from postanhepatic small bowel edema or oversized grafts despite partial LTx. For those instances we developed the "sandwich" technique. This procedure incorporates advantages of previous techniques with some additional advantages described herein. Use of polyglactin 910/silicone meshs in a sandwich fashion allows for one-stage permanent abdominal closure without major loss of body plasma fluids after pediatric LTx. So far our clinical experience with this technique has been very satisfying.

Abdomen↗