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Biomedical subjects

P Oberwalder

Publications and source records attributed to P Oberwalder.

16 recordsLinked to original sources
PubMed2003

Cardiac MR in robotic heart surgery for preoperative identification of the target vessel and precise port placement--a theoretical model.

BACKGROUND: The identification of the ideal anastomosis site and the proper port placement are critical for the success of closed-chest robotic surgery. We investigated a new systematic procedure for precise port placement for TECABs. METHODS: We used trigonometry and a human thoracic model to determine the optimal working angles between anastomotic plane, instruments, and endoscope. We then applied the results to seven human subjects as follows: 1. A navigation grid was located extrathoracically before cardiac MR examination. 2. The ideal anastomosis site was defined with the MR. Intrathoracic distances and angles were computed with cardiac MR software and projected onto the thorax. 3. The ideal port placement points were marked on the thorax. RESULTS: The optimal working angle between endoscope and instruments was 35 degrees. 0 degrees and 90 degrees angles were associated with a significant reduction in visualization, technical ease, quality and anastomosis time. The course of the LAD was identified in all seven volunteers with MR. Mean deviation of the endoscope port from the medioclavicular line was 4.3+/-2.1 cm and of the instrument ports from the anterior axillary line 8.4+/-2.4 cm. CONCLUSIONS: Cardiac MR in combination with the navigation grid proved suitable for the visualization of coronary vessels for individually calculating port placement points on the thorax.

Adult↗
PubMed2002

Cardiac myxomas: 24 years of experience in 49 patients.

OBJECTIVES: In this single-center study we reviewed our experience with a significant number of cardiac myxoma cases occurring over the past two decades. PATIENTS AND METHODS: Cardiac myxomas represented 86% of all surgically treated cardiac tumors at our center. Specifically, there were 49 consecutive patients, each with at least one myxoma. A detailed clinical, immunological, and echocardiographic long-term examination of 37 patients revealed one recurrent myxoma. RESULTS: Most myxomas originated from the left atrium (87.7%), but also much less frequently from the mitral valve (6.1%), from the right atrium (4.1%), and from the left and right atria (2.0%). The myxomas produced a prolapse into the left ventricle in 40.8% of the patients, mitral stenosis in 10.2%, and threatened left ventricular outflow tract obstruction in 2.0%. Multiple myxomas were found in 20.4% of the patients. Cardiac signs appeared in 93.9% of the patients. Preoperative embolic events had occurred in 26.5%. Immunologic alterations were present in 87.5%. For resection, a bilateral atriotomy was used. An additional aortotomy was needed to expose one mitral valve myxoma. Postoperatively, 81.1% of the patients remained without cardiac symptoms. The early mortality rate was 2.0% and the late mortality rate was 6.1%. Long-term prognosis was excellent with an actuarial survival rate of 0.74. Specific immunologic alterations were found in 71.4% of the patients. The actuarial freedom from reoperation of the myxoma was 0.96. The rate of reoperations was low with 2.0% after 24 years. CONCLUSIONS: Myxomas were usually detected and operated on in symptomatic patients. A high index of suspicion seems important for early diagnosis. Immunologic findings may play an additional role in confirming the diagnosis and the recurrence of a myxoma. Immediate surgical treatment was indicated because of the high risk of embolization or of sudden cardiac death. Also, a familial genesis must be excluded in myxoma patients.

Adult↗
PubMed2001

Endovascular stent-graft repair of acute thoracic aortic dissection--early clinical experiences.

BACKGROUND: Standard treatment of acute thoracic aortic dissection type B is the medical therapy used for most patients, according to Stanford. Surgical therapy involves a high mortality rate and is reserved for patients with complicated dissections. We report from four patients with acute thoracic aortic dissection, treated endoluminally by stent-graft implantation. METHODS: Four patients with complicated acute thoracic aortic dissections type B were treated endoluminally by transfemoral stent-graft implantation. Preoperative evaluation was performed with spiral-computed tomography and calibrated aortography. The Talent stent-graft system (Metronic) was used in all patients. RESULTS: The primary entry tear could be sealed successfully and complete thrombosis of the false thoracic aortic lumen was obtained in all cases. In one patient, transposition of the left subclavian artery was performed, in two patients the stent-grafts had to be placed across the origin of the left subclavian artery. No severe intra- or postoperative complications occurred. CONCLUSION: Endoluminal treatment of acute thoracic aortic dissection seems to be a less invasive and effective therapy. Long-term results for this method are necessary.

Acute Disease↗
PubMed2001

Intentional left subclavian artery occlusion by thoracic aortic stent-grafts without surgical transposition.

PURPOSE: To report the consequences of endoluminal deployment of stent-grafts in the thoracic aorta with intentional occlusion of the left subclavian artery. CASE REPORTS: Three patients with an aortic type-B dissection and 1 with a thoracic aneurysm were treated endoluminally with Talent stent-grafts implanted over the ostium of the left subclavian artery without prior surgical subclavian-carotid transposition. The primary intimal tears were sealed and the degenerative aneurysm excluded; blood pressure in the left arm was significantly diminished immediately after the stent-graft was released, but adequate collateral retrograde perfusion via the left vertebral artery was apparent in all patients. No neurological deficit and no symptoms of left arm ischemia were observed in a follow-up that ranged from 14 to 20 months. CONCLUSIONS: Our limited experience shows that occlusion of the left subclavian artery with a stent-graft is well tolerated. If ischemic symptoms occur, a transposition procedure can be performed on an elective basis.

Aged↗
PubMed2000

Left ventricular outflow tract obstruction due to valve myxoma.

A life-threatening left ventricular outflow tract obstruction developed in a 26-year-old man because of a very uncommon myxoma emerging from the ventricular side of the mitral valve. Immediate surgical treatment was indicated because of high-risk factors reported herein. After transaortic resection of a single myxoma, the progress of this patient has been excellent, especially as a familial myxoma could be excluded.

Adult↗
PubMed2000

[Transposition of the subclavian artery with endovascular stent graft implantation for therapy of acute type B aortic dissection].

We report about a patient with a thoracic aneurysm caused by an acute type-B dissection. Due to the concomitant affections the risk of surgery was distinctly increased, the reconstruction was performed endo vascular by stentgraft implantation (Talent, World Medical Systems, Sunrise FL) after transposition of the left subclavian artery to create a sufficient neck for the proximal stent placement. Endoluminal treatment seems to be a promising, less invasive alternative method in the treatment of acute aortic dissections.

Acute Disease↗
PubMed2000

Cerebrospinal fluid drainage to reverse paraplegia after endovascular thoracic aortic aneurysm repair.

PURPOSE: To report a case of endovascular descending thoracic aortic aneurysm (TAA) repair in which delayed-onset paraplegia was reversed using cerebrospinal fluid (CSF) drainage. METHODS AND RESULTS: A 74-year-old patient with a 6.0-cm TAA underwent endovascular stent-graft repair that involved overlapping placement of 3 Talent devices to cover the 31-cm-long defect. Twelve hours later, a neurological deficit occurred manifesting as left leg paralysis with paresis on the right. After urgent intrathecal catheter placement and drainage of cerebrospinal fluid for 48 hours, the neurological deficit resolved. The patient's clinical condition was normal and endoluminal exclusion of the TAA remained secure at 8-month follow-up. CONCLUSIONS: This case demonstrates the potential therapeutic role for CSF drainage to reduce the complications of spinal cord injury after endovascular thoracic aneurysm repair.

Aged↗
PubMed1998

Successful repair of mega aorta using reversed elephant trunk procedure.

The case reported is of a patient with mega aorta and a symptomatic thoracoabdominal aortic segment. Successful treatment involved resection and graft replacement of the thoracoabdominal segment as an initial procedure using a "reversed elephant trunk" technique, followed by resection and replacement of the ascending aorta and transverse aortic arch as the second stage.

Aged↗
PubMed1996

Concomitant procedures in the small versus standard aortic root.

BACKGROUND AND AIMS OF THE STUDY: Aortic valve replacement (AVR) in the small aortic root (SAR) has always been a severe challenge with an uncertain surgical outcome. The purpose of this study was to assess the surgical and clinical performance of 19 mm and 21 mm CarboMedics valves (CPHV) based on a review of valve-related morbidity and mortality over a period of six years. METHODS: A total of 361 patients undergoing aortic valve replacement (AVR) with the CPHV between January 1989 and August 1995 was subdivided and studied. (i) Group A patients (n = 137) received 19 mm or 21 mm prostheses; subgroup AI (n = 85) underwent isolated AVR and subgroup AII (n = 52) underwent AVR with associated cardiac procedures. (ii) Group B patients (n = 224) were given 23 mm or larger prostheses; subgroup BI (n = 147) underwent isolated AVR and subgroup BII (n = 77) underwent AVR with concomitant cardiac procedures. RESULTS: Hospital mortality was group A 7.3% versus group B 4.9%. Cumulative survival after six years was 83.7% in AI and 76.9% in AII versus 72.1% in BI and 77.4% in BII. There were no significant statistical differences between the subgroups concerning cardiac mortality. Thromboembolic events occurred with a linearized rate of 1.41%/pty in group A versus 1.03%/pty in group B, the incidence of anticoagulant-related major hemorrhage was 1.41%/pty in group A versus 1.20%/pty in group B and that of periprosthetic leakage 1.69%/pty in group A versus 1.89%/pty in group B. CONCLUSION: Our results demonstrate that this bileaflet prosthesis is highly efficient in patients with small aortic roots undergoing AVR with or without associated procedures.

Adolescent↗
PubMed1995

[Total cavo-pulmonary connection as a therapeutic principle in anatomical and functional univentricular heart].

The original Fontan operation was employed for patients with tricuspid atresia, but its application has been extended to a broad spectrum of congenital cardiac defects with a functional or anatomical single ventricle. From 1989 to 1995, 35 patients (23 males, 12 females) underwent a modified Fontan procedure; their age ranged from 14 months to 15 years (mean 5.1 a). Indications for operation were the following: D(S)ILV = 16, TA = 9, MA = 3, TGA with straddling AV-valve = 2, DORV = 4 and criss-cross heart = 1. The same surgical technique was utilized in all patients with redirection of the systemic venous return by means of a bidirectional cavopulmonary anastomosis and an intraatrial baffle, adaptable to all the various forms of underlying anatomy. Associated anomalies such as dextrocardia, coarctation, anomalous systemic or pulmonary venous return, subaortic stenosis and situs anomalies were present in 26%, 9%, 26%, 9%, and 20%, respectively. 12 patients were presumed to be at high risk and underwent a two-stage procedure (n = 7 bidirectional Glenn preceding the definitive repair and n = 5 a fenestration of the intraatrial baffle). Risk factors in our group of patients were: age under 2 years, abnormal systemic venous drainage, stenotic pulmonary arteries, PVR over 2 Wood units, mPAP over 15 mmHg, AV-valve incompetence, subaortic obstruction and ventricular dysfunction. Two patients had failure of the total cavo-pulmonary connection necessitating the take-down to a bidirectional Glenn anastomosis in the early postoperative period, with one death. Hospital mortality was 24% (n = 8). One child did not survive complications following the fenestration closure 4 months postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

[Possibilities for saving homologous blood in heart surgery].

The risks of blood transfusion in context with the increasing number of operative open-heart procedures and the linked increased demand for blood products present a challenge to find methods of saving homologous blood. On the one hand there is increasingly less blood at the surgeon's disposal and on the other hand there is the threat of infectious complications with viruses of the HIV or the hepatitis group, as well as allergic reactions. At present we are developing the concept of blood saving as a programme which should work without excess demands on the staff and which can be adjusted to the needs of the individual patient. The programme consists of the following components: preoperative self donation, use of cell saver, acceptance of e relatively low hematocrit, medication to alter the coagulation process and blood-less priming.

Aprotinin↗
PubMed1985

Orthotopic heart replacement by nonpulsatile axial blood pumps.

In the last decade, there have been many experiments with nonpulsatile blood pumps to perform functional heart replacement by biventricular assist devices. To determine if life is sustainable with nonpulsatile blood flow, two nonpulsatile blood pumps were implanted in the orthotopic position as an artificial heart after removal of the natural heart in extracorporeal circulation. In three preliminary experiments, the feasibility of total heart replacement with nonpulsatile implantable blood pumps was shown.

Animals↗
PubMedDate not supplied

Treatment of acute aortic type B dissection with stent-grafts.

PURPOSE: To evaluate the feasibility of endoluminal stent-grafts in the treatment of acute type B aortic dissections. METHODS: In five patients with acute aortic type B dissections, sealing of the primary intimal tear with an endoluminal stent-graft was attempted. Indication for treatment was aneurysm formation in two patients and persistent pain in three patients. One of the latter also had an unstable dissection flap compromising the ostium of the superior mesenteric artery. The distance from the intimal tear to the left subclavian artery was <0.5 cm in four patients, who had typical type B dissections. In one patient with an atypical dissection the distance from the primary tear to the left subclavian artery was 4 cm. This patient had no re-entry tear. Talent tube grafts (World Medical Manufacturing Cooperation, Sunrise, FL, USA) were used in all patients. RESULTS: Stent-graft insertion with sealing of the primary tear was successful in all patients. The proximal covered portion of the stent-graft was placed across the left subclavian artery in four patients (1x transposition of the left subclavian artery). Left arm perfusion was preserved via a subclavian steal phenomenon in the patients in whom the stent-graft covered the orifice of the left subclavian artery. The only procedural complication we observed was an asymptomatic segmental renal infarction in one patient. In the thoracic aorta thrombosis of the false aortic lumen occurred in all patients. In one patient the false lumen of the abdominal aorta thrombosed after 4 weeks; in the other three patients the status of the abdominal aorta remained unchanged compared with the situation prior to stent-graft insertion. As a late complication formation of a secondary aneurysm of the thoracic aorta was observed at the distal end of the stent-graft 3 months after the primary intervention. This aneurysm was treated by coaxial insertion of an additional stent-graft without complications. CONCLUSION: Endoluminal treatment of acute type B aortic dissections seems to be an attractive alternative treatment to surgical repair. Thrombosis of the false lumen of the thoracic aorta can be induced if the primary tear is sealed with a stent-graft. This could protect the dissected thoracic aorta from delayed rupture.

Acute Disease↗