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Biomedical subjects

Michael P Siegenthaler

Publications and source records attributed to Michael P Siegenthaler.

12 recordsLinked to original sources
PubMed2006

Neurophysiological monitoring during thoracoabdominal aortic endovascular stent graft implantation.

OBJECTIVE: The aim of this study was to evaluate the benefit of neurophysiological monitoring during thoracic and thoracoabdominal endovascular stent graft implantation. METHODS: The spinal cords of 21 patients undergoing endovascular stent graft implantation on the thoracic and thoracoabdominal aorta were monitored with transcranial motor-evoked potentials (tcMEP) and somatosensory-evoked potentials (SSEP). All patients underwent mild systemic hypothermia (34-35 degrees C), constant cerebrospinal fluid (CSF) pressure and vital parameter monitoring. If CSF pressure exceeded 15 mmHg, CSF-drainage was carried out. RESULTS: Three of the 21 patients (14%) exhibited short-term loss of tcMEP and SSEP after the deployment of the self-expanding endoprosthesis. We observed an intraoperative recovery of the evoked potentials in all cases. CSF-drainage was necessary in three of them. One patient, whose potentials were stable intraoperatively, developed paraparesis 3 weeks after the intervention. CONCLUSIONS: Neurophysiological monitoring has proved to be an ideal monitoring method to detect spinal cord ischemia during thoracic and thoracoabdominal endovascular stent graft implantation. Due to the advantages of endovascular therapy (no aortic cross-clamping, continuous distal perfusion, and no reperfusion injury), changes in potentials were seldom observed.

Aged↗
PubMed2006

Mechanical reliability of the Jarvik 2000 Heart.

BACKGROUND: Device failure is a limitation of permanent mechanical circulatory support. We studied the mechanical reliability of the Jarvik 2000 Heart, an axial flow pump with ceramic bearings designed to provide more than 10 years' durability. METHODS: The Jarvik 2000 Heart was implanted in 102 patients between April 2000 and December 2004. Eighty-three pumps with an abdominal driveline were implanted as a bridge-to-transplantation, and 19 with postauricular power supply as lifetime therapy. Eighteen pumps were recovered intact after clinical use and run continuously on the bench to further assess durability. RESULTS: No implantable component failure occurred either in patients or during bench testing. The cumulative pump run-time was 110 years: 59 years overall in vivo and 51 years in vitro. The mean support time for bridge-to-transplant recipients was 159 days, and for discharged lifetime-therapy recipients 551 days. Six recipients were supported moer than 2 years, with the longest ongoing approaching 5 years. External cables caused three system failures, with a 95% freedom from system failure at 4 years. Device malfunctions, related to external cables (9) and lack of a backup battery (1), caused no adverse consequences. Before introduction of noncorrosive, gold-plated stainless steel connectors, corrosion was observed on three connectors to the retroauricular power supply. CONCLUSIONS: The Jarvik 2000 Heart has had no implantable component failure. Meaningful durability data and failure mode can only be established by real-time testing in patients. The reliability and dependability of this device, in addition to the exchangeability of external components, give promise for long-term circulatory support in critically ill heart failure patients.

Equipment Failure Analysis↗
PubMed2006

Perioperative management to improve neurologic outcome in thoracic or thoracoabdominal aortic stent-grafting.

BACKGROUND: Thoracic or thoracoabdominal aortic stent-graft repair has shown a reduction in morbidity and mortality rates due to the procedure's advantages (no aortic cross-clamping, continuous distal aortic perfusion, no reperfusion injury). However, 3% to 12% of the patients are at risk of spinal cord ischemia. We investigated spinal cord protective measures with evoked potentials, cerebrospinal fluid drainage, and prevention of hypotension to minimize postoperative neurologic deficit. METHODS: Between November 2000 and July 2005, vital parameters and spinal cord function were monitored, including cerebrospinal fluid pressure and transcranial motor-evoked and somatosensory-evoked potentials in 36 stent-graft procedures (31 patients) on the thoracic or thoracoabdominal aorta. RESULTS: Stent-graft placement was technically successful in all patients. We achieved a survival rate of 100% without neurologic deficit after fast-track extubation. Eleven of 31 patients exhibited changes in evoked potentials during stent-graft deployment. In 12 of 31 patients (including the 11 with evoked potential alterations), cerebrospinal fluid pressure exceeded 15 mm Hg. Cerebrospinal fluid drainage and vital parameter adjustment were executed in those instances. We observed intraoperative evoked potential total recovery in 10 of 11 patients after these interventions. CONCLUSIONS: Interventions to improve spinal cord perfusion led to total recovery of spinal function in most patients (10/11). Therefore, spinal cord protective measures with motor- and somatosensory-evoked potential monitoring, cerebrospinal fluid drainage, and prevention of hypotension can reduce the incidence of spinal cord ischemia and improve the neurologic outcome of patients undergoing endovascular thoracic or thoracoabdominal aortic repair.

Adult↗
PubMed2005

Advanced heart failure: feasibility study of long-term continuous axial flow pump support.

AIMS: A lack of donor hearts has stimulated interest in using blood pumps to treat severe heart failure. We tested the hypothesis that a new continuous flow circulatory assist device could be employed safely to relieve symptoms of heart failure and evaluated the potential to prolong life. METHODS AND RESULTS: An intracardiac axial flow pump was implanted in 17 heart failure patients [idiopathic dilated (12), ischaemic (4), or amyloid cardiomyopathy (1)]. All were deemed ineligible for transplantation. Implantation of the device was by left thoracotomy (15) or median sternotomy (2). Power delivery was by a skull-mounted titanium pedestal. All patients survived surgery. None needed right ventricular support. There were three hospital deaths, two early from subdural haematoma and aortic thrombosis, one late after switching to transplantation. A total of 14 patients left hospital with a cumulative support-time of 15.9 years (median: 293 days, interquartile range: 286 days, 1-44 months). Actuarial 1-, 2-, and 3-year survivals were 56, 47, and 24%, respectively. There was no pump failure. Quality of life scores improved. Two superficial pedestal infections were successfully treated. Four patients had cerebral thrombo-embolism: two early events attributed to inadequate anticoagulation and two late with near-complete resolution. An improved anticoagulant regime addressed this problem. Late death occurred in five patients from battery disconnection, subdural haematoma, bowel ischaemia, respiratory failure, and after cardiac transplantation. CONCLUSION: Continuous flow blood pumps provided symptomatic relief of severe heart failure with high quality of life. Event-free survival reached 4 years. Analysis of adverse events led to improved management strategies. There is potential for widespread use of blood pumps in the community. A controlled trial is required.

Aged↗
PubMed2005

Anterior approach to implant the Jarvik 2000 with retroauricular power supply.

The retroauricular power supply of the Jarvik 2000 (Jarvik Heart Inc, New York, NY) left ventricular assist device is suitable for permanent support, as it is associated with fewer infections than conventional drivelines. Implantation through a left-lateral thoracotomy limits the performance of additional cardiac procedures. We describe a technique that used a sternotomy for the implantation of the Jarvik 2000 with retroauricular power supply in two patients. The retroauricular power supply of the Jarvik 2000 can be provided with an anterior approach, allowing full surgical access to the heart. If the outflow graft to the ascending aorta indeed reduces aortic stasis and thromboembolic events, the anterior approach with retroauricular power delivery might evolve into a standard procedure.

Aged↗
PubMed2005

Implantation of the Jarvik 2000 left-ventricular-assist-device: role of the maxillofacial surgeon.

The Jarvik 2000 system of axial-flow LVAD-is implanted for permanent mechanical circularly support in patients with end-stage heart failure waiting to undergo heart transplantation. The battery is connected with a power plug to the percutaneous skull-mounted footplate, which is monocortically fixated to the retro auricular bone. Patient selection should be highly specific, including careful preoperative evaluation. No device failures have been published so far, but complications can occur due to heparinisation. We describe the procedure from the perspective of the maxillofacial surgeon and give suggestions to prevent surgical complications.

Cardiac Output, Low↗
PubMed2004

Implantable left ventricular assist device for treatment of pulmonary hypertension in candidates for orthotopic heart transplantation-a preliminary study.

OBJECTIVES: Elevated pulmonary vascular resistance (PVR) unresponsive to pharmacological intervention is a major limitation in heart transplantation (HTX). The post-operative course of these patients is associated with an increased risk of life-threatening right heart failure. We evaluated the efficiency of an implantable left ventricular assist device (LVAD) to decrease PVR by unloading the left ventricle and to lower the risk of later orthotopic HTX. METHODS: Six patients with end-stage heart failure (NYHA class IV) and 'fixed' pulmonary hypertension (PVR 5.7+/-0.7, range 4.4-6.5 Wood units) were analyzed. Despite maximal pharmacological intervention at initial evaluation (oxygen inhalation, nitrates, alprostadil infusion) PVR could not be reduced to under 2.5 Wood units. Four patients received a TCI Heartmate, one patient a Novacor, and one patient a Jarvik 2000. RESULTS: All patients survived the LVAD implantation, four patients could be discharged from hospital. Cardiac index and pulmonary artery pressure values returned to normal during the early post-operative phase. After a mean support time of 191+/-86 days PVR had fallen to 2.0+/-1.2 (range 0.8-3.6) Wood units. All patients could be bridged to transplantation, one patient died 3 months after transplant, five patients are still alive after a mean follow-up of 16.2+/-10.5 months. CONCLUSIONS: Mechanical support using an implantable LVAD is a very efficient approach with an acceptable risk to treat severe pulmonary hypertension in end-stage heart failure patients before HTX. Adequate reduction of PVR can be expected within 3-6 months. Subsequent HTX is associated with a good outcome.

Adolescent↗
PubMed2002

Implantation of the permanent Jarvik-2000 left ventricular assist device: a single-center experience.

OBJECTIVES: We sought to evaluate the surgical results and effects of continuous support with the permanent Jarvik-2000 left ventricular assist device (LVAD). We report the early outcomes. BACKGROUND: A shortage of transplant donors necessitates the testing of alternative treatments. The Jarvik-2000 is an axial flow pump with a percutaneous retro-auricular power connector, designed for permanent use. METHODS: Patients with severe heart failure (HF), unsuitable for heart transplantation or conventional LVAD support, were offered implantation. The surgical approach included a left lateral thoracotomy. The device was implanted into the left ventricular apex on femoro-femoral bypass. It is set to allow pulsatile flow with an aortic valve opening. Anticoagulation is adjusted the same as for patients with a heart valve. RESULTS: Between May 2001 and August 2001, we implanted the Jarvik-2000 in two patients with dilated cardiomyopathy and in one with cardiac amyloidosis, all with severe HF (cardiac index 1.8 +/- 0.3 l/m(2) per min). One patient required preoperative inotropic support. All patients did well, with no repeat operations or infections. Patients received 4.3 +/- 3.2 packed red blood cells and were intubated at 14 +/- 3 h, and the intensive care unit stay was 7.0 +/- 0.5 days. The cardiac index increased from 3.7 +/- 1.5 l/min per m(2) at 8,000 rpm to 5.9 +/- 2.9 l/min per m(2) at 12,000 rpm. All patients currently have mild hemolysis not requiring transfusion. The following postoperative events were recorded: a transient ischemic attack with complete recovery, a short re-intubation due to ventricular arrhythmia, loss of consciousness with a battery change while standing, knee-joint effusion after ergometry training, a minor wound problem and a short hospital re-admission due to dehydration. Patients were discharged home after 49 +/- 7 days; one has returned to work. All quality-of-life scores have improved. CONCLUSIONS: The permanent Jarvik-2000 appears safe. It can be used for dilative or restrictive disease. The Jarvik-2000 might prove a valid option for the long-term treatment of patients with severe HF.

Amyloidosis↗
PubMed2002

The Jarvik 2000 Heart. Clinical validation of the intraventricular position.

OBJECTIVE: Heart failure is now a public health epidemic. Donor hearts are severely restricted in availability. Permanent mechanical circulatory support or bridge to myocardial recovery are emerging alternatives. After extensive laboratory experience we sought to evaluate the intraventricular Jarvik 2000 Heart in patients with endstage heart failure. METHODS: The Jarvik 2000 Heart is a novel thumb-sized left ventricular assist device (LVAD) which is fitted within the apex of the native left ventricle. A vascular graft off loads this to the descending thoracic aorta. The pump rotor spins at between 8000 and 12,000 rpm providing 5-6 litres blood flow per minute. We have used the device with skull-mounted power delivery for seven permanent implants and trans-abdominal drive line for ten bridge-to-transplant patients. RESULTS: All patients survived the operation. Three died from non-device related complications. Survivors had early resolution of heart failure with return to NYHA I/II. All had pulsatile circulation. The device was user-friendly and imperceptible to the patient. Both the pump and native left ventricle contributed to the cardiac output during exercise. Seven patients have been transplanted successfully. All explanted devices were free from thrombus formation. Two permanent implant patients left hospital as early as 3 weeks postoperatively. CONCLUSIONS: The Jarvik 2000 is an effective user-friendly LVAD which allows early discharge from hospital. The intraventricular position has distinct advantages especially through absence of an inflow cannula. Synergy develops between the LVAD and native left ventricle. Early experience suggests that this may be a realistic LVAD to treat heart failure routinely in the outpatient setting.

Adult↗