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At least 991 records · Page 55Linked to original sources
PubMed1994

New method for mechanistic studies of cardiomyoplasty: three-dimensional MRI reconstructions.

The imaging modalities used to study the mechanism of cardiomyoplasty, such as echocardiography and radionuclide scintigraphy, are seriously limited by their two-dimensional format. Radiofrequency-pulse-tagged magnetic resonance imaging was used to generate three-dimensional reconstructions of the left ventricle throughout the cardiac cycle after cardiomyoplasty. In 2 dogs that had undergone conditioned, right anterior cardiomyoplasty, wrap stimulation with alternating heartbeats was found to produce marked translation of the left ventricle in the short-axis plane, rotation around the long axis, and displacement along the long axis with net long-axis compression; there was no augmentation of radial squeeze. The findings from this study suggest that any systolic augmentation produced by the right anterior wrap is due primarily to long-axis compression. Our study demonstrates a new, more accurate technique of assessing the mechanical effects of cardiomyoplasty in three dimensions, thus permitting a more rational optimization of wrap configurations, and emphasizes the perils of using standard two-dimensional imaging modalities in this setting of exaggerated three-dimensional motion.

Animals↗
PubMed1988

A rapid method for determining the need for mechanical support of the right ventricle.

Right ventricular failure following cardiac surgery must be rapidly diagnosed and treated to minimize injury to the heart. Switching from aortic to pulmonary artery perfusion during cardiopulmonary bypass is a method of rapidly testing the adequacy of right ventricular function and supporting the ventricle if necessary. A centrifugal pump has been used for long-term support for two cases managed in this manner.

Assisted Circulation↗
PubMed2003

Recent improvements in outcome with the Novacor left ventricular assist device.

BACKGROUND: The Novacor implantable, electrically powered, wearable, left ventricular assist device (LVAD) has been used as a bridge to transplantation at our institution since 1994. Recent changes in protocol have resulted in a decreased incidence of infections, thromboembolism, and mortality. METHODS: We reviewed the medical records of all 43 patients who received implantable LVADs at the Mount Sinai Medical Center. After 1998, a number of protocol modifications were instituted. Vascular grafts were changed from a low-porosity, woven polyester (Cooley) to a gelatin-sealed, knitted polyester graft (Vascutek), the devices were implanted pre-peritoneally rather than in the posterior rectus sheath, and extensive drainage of the chest and pre-peritoneal pocket was used. The following anti-coagulation regimen was used: low-molecular-weight Dextran for 1 day, initiated after chest tube drainage <50 cc/hour; then IV heparin for 10 to 14 days, beginning at 500 U/hour, slowly increasing partial thromboplastin time to 1.5 to 2 x control; and finally Coumadin, maintaining the international normalized ratio at 2.5 to 3.5. Daily aspirin, 325 mg, was begun on post-operative Day 7. We compared 22 patients who electively underwent surgery before the changes, Group I, with 18 patients treated thereafter, Group II. RESULTS: Groups I and II were well matched with regard to age (47 vs 44 years); cause of heart failure (idiopathic, 50% vs 44%; ischemic, 50% vs 56%), and duration of support (79 vs 76 days). The incidence of thromboembolic cerebrovascular events was significantly less in Group II (6%) than in Group I (23%), p = 0.025. The incidence of bleeding increased mildly in Group I. Pocket infections occurred in 27% of Group I patients vs 11% of Group II patients, p = 0.018. Only 2 patients (11%) in Group II died while receiving device support, vs 7 (32%) in Group I, p = 0.019. CONCLUSIONS: Our results indicate that pre-peritoneal implantation, use of a new generation of vascular grafts, extensive drainage, and a more restricted anti-coagulation regimen improve outcome after Novacor LVAD implantation for advanced heart failure.

Adolescent↗
PubMed2003

Mechanical Circulatory Support device database of the International Society for Heart and Lung Transplantation: first annual report--2003.

Over the last 2 decades, mechanical circulatory support devices have been developed with the goal of supporting patients with advanced heart failure as a bridge to cardiac transplantation, a bridge to recovery, and an alternative to transplantation (also called chronic or destination therapy). The current generation of devices provides a differentiated spectrum of circulatory support. The major limitations of mechanical circulatory support devices are infection, coagulopathies and device dysfunction. The Scientific Council on Mechanical Circulatory Support of the International Society for Heart and Lung Transplantation has established an international database to generate critical data to advance knowledge about the effectiveness of mechanical circulatory support device therapy for one of the most difficult and costly contemporary medical problems, the malignant syndrome of advanced heart failure.

Adolescent↗
PubMed1999

Evolving short-term and long-term mechanical assist for cardiac-failure -- a decade of experience in Münster.

Technological advances and growing expertise has lead to referral of much sicker patients with a greater incidence of heart failure prior to and after cardiac surgical procedures. The diversity of the heart failure patient cohort mandates a differentiated protocol for mechanical support adapted to the clinical requirements. It is desirable to have appropriate mechanical support available for different circumstances of heart failure. In this paper, we review the first decade of the Muenster University Hospital experience with the use of intra-aortic ballon pump, extracorporal membrane oxygenators, short term uni- and biventricular assist systems such as Thoratec and Medos devices, as well as long term left ventricular assist systems such as the TCI Heartmate and the Novacor system. The patient profiles, indications, contraindications, and future trends are reviewed within the framework of a contemporary university hospital Servive.

Assisted Circulation↗
PubMed1988

Performance characteristics of a disposable ventricle assist device.

A disposable ventricle assist device (VAD) including atrium, ventricle and trileaflet valves (all polyurethane) can be driven either a) by its original self adjusting drive unit (ABIOMED BVS 5000) or b) by a standard intra-aortic balloon pump console (DATASCOPE). Maximum flow in vitro was 4.3 l/min with the original drive console versus 9.2 l/min for activation with the intra-aortic balloon pump console. Performance characteristics of the VAD were evaluated in 11 bovine experiments. In vivo left ventricular assist for up to 24 hours with VAD and either original drive console or standard intra-aortic balloon pump console showed superior flow on activation with the intra-aortic balloon pump console (5.3 +/- 1.7 l/min) versus original drive console (3.5 +/- 0.5 l/min). After 6 hours of assist (before any transfusions) there was no significant difference in classic parameters for evaluation of blood trauma such as plasma hemoglobin production, LDH production and platelet depletion. We conclude that VAD is extremely simple to use. Activation by an intra-aortic balloon pump console enables significant increase of VAD-output without detectable increase of blood trauma. Successful weaning of VAD activated with standard intra-aortic balloon pump console was possible in a first clinical application.

Aortic Valve Insufficiency↗
PubMedDate not supplied

Pulsatile pediatric ventricular assist devices.

A pulsatile pediatric ventricular assist device (PVAD) is being developed at The Pennsylvania State University to provide mechanical circulatory support in infants and children. The PVAD is based on the design of the adult-sized Pierce-Donachy VAD (Thoratec VAD). The infant-sized PVAD has a dynamic stroke volume of approximately 13 ml. A larger 25-ml size for children is also planned. The stroke volumes, beat rates, and pulsatility are comparable to normal physiologic values. The expected maximum duration of use is 6 months. The PVAD is intended to be placed paracorporeally, although the pump may be implanted for bridge-to-transplant applications. The pneumatically actuated PVAD uses a full-to-empty control mode, which allows maximum flexibility in its application for left, right, or biventricular assistance. The device may be used with atrial or ventricular inlet cannulation, with blood return to the aorta or pulmonary artery. In vitro testing is underway to measure hydrodynamic performance, hemolysis, and flow velocities using particle image velocimetry. In vivo implantation studies will be performed in juvenile goats or sheep after the completion of baseline studies to assess hematology and surgical fit.

Animals↗
PubMedDate not supplied

Managing the post-left ventricular assist device patient.

The implantation of ventricular assist devices allows the opportunity for patients with intractable heart failure to have improved quality and quantity of life. The devices may be implanted after failed attempts to wean from bypass, as a bridge to transplantation, or as destination therapy. Key issues following the implantation of assist devices include the prevention of right ventricular failure, appropriate pharmacologic management, prevention and management of infection, and detection and treatment of device dysfunction.

Assisted Circulation↗
PubMedDate not supplied

Retrospective analysis of the psychologic effects of mechanical circulatory support.

There is an increasing need to evaluate the psychologic impact of circulatory support because of the growing use of mechanical assist devices. Twenty-seven people, 12 survivors of mechanical circulatory assistance and 15 family members, were surveyed; nonsurvivors' families were not surveyed. The 12 survivors (ages 18 to 66 years; mean, 43 years) had been supported with Pierce-Donachy ventricular assist devices (nine patients) and the Novacor left ventricular assist system (one patient). One patient received a centrifugal pump, and one was supported with extracorporeal membrane oxygenation (ECMO). Duration of support ranged from 8 hours to 90 days (mean, 23 days). Ten people surveyed were spouses of these patients, and five were parents of children who had been supported with ECMO. Three patients were supported longer than 3 weeks, and four patients were awake and ambulatory during support. Financial worries were not a concern for 80% of the parents but were a concern for 80% of the spouses. Eighteen percent of the patients believed they were treated as an experiment, whereas 40% of their spouses thought they were. None of the parents thought their child was treated as an experiment. Sixty-seven percent of the patients stated that they have returned to a normal life-style, and 75% feel they have a brighter outlook on life. Six patients have returned to work, two are retired, two are disabled, and two have physical capabilities to work but choose not to. Eighty-nine percent of all those surveyed would recommend an assist device to someone who needed one. Although these procedures are often associated with severe medical and psychologic complications, 74% of the patients would agree to a second implant.

Adult↗
PubMed1989

[Clinical assessment of anticoagulation therapy during left ventricular assist with artificial heart: induction with protease inhibitor].

Left ventricular assist device was attached to five patients suffered from severe low cardiac output after open heart surgery. In two patients, anticoagulation therapy with heparin started just after the operation. Repeated operations for hemostasis were required because of massive bleeding in these two patients. Anticoagulation therapy was not performed in another one, and thrombus formation in the device was recognized in this patient. In the other two patients, anticoagulation therapy was started with large dose of protease inhibitor (gabexate mesilate or nafamstat mesilate). Heparin infusion was combined with protease inhibitor during the period of weaning from the device. Thrombosis and massive bleeding were not recognized in these two patients, and they were able to wean from the device successfully.

Aged↗
PubMed1989

Centrifugal pump or pneumatic ventricle for short-term mechanical circulatory support?

Two comparable groups of four Holstein calves were implanted with different left ventricle assist devices: the Centrimed centrifugal pump (CP) (Sarns Inc.) or the UTAH 85 VAD pneumatic ventricle (University of Utah). Operative procedure, inflow and outflow cannulae, monitoring, heparinization, were identical in both groups. No transfusion was ever required. The study was terminated after three days and autopsy was performed on the calves. Left ventricular unloading provided by both devices was complete (LVEDP less than 1 mmHg) and identical. LV bypassed flow rate was higher in CP (0.045 L/min/kg) than in UTAH 85 VAD (0.035 L/min/kg) but with no statistical difference. Blood trauma was comparable in the two groups. Daily blood samples did not show any significant changes from baseline values in creatinine, hematocrit, fibrinogen. Platelet loss from initial level was 30%; serum lactate dehydrogenase rose 150% with no significant difference in the two groups; plasma free hemoglobin never reached significant values. At autopsy, thrombotic deposits on cannuale and renal infarction rate were similar. CP housing had to be changed every day, whereas no technical failure was ever observed with the UTAH 85 VAD. Clinical response and blood damage of the two pumps used as LVAD were the same. Considering the CP has to be replaced every 24 h, the cost of three CP's would be comparable to one Utah UVAD-85 if polyurethane tricusp semi-lunar valves are used in the latter. Until the UTAH-85 VAD becomes commercially available, simple valveless low-cost CP are very attractive for short-term mechanical support.

Animals↗
PubMed1988

Staged cardiac transplantation. Total artificial heart or ventricular-assist pump?

Because of donor organ unavailability, staged cardiac transplantation has been performed in eight patients with The Pennsylvania State University pneumatic total artificial heart (two patients) or with the Pierce-Donachy ventricular-assist pump (six patients). Of the six patients who received the ventricular-assist pump, four received cardiac allografts after 3, 11, 21, and 31 days of pump support, respectively. Two patients died before transplantation; the causes of death were non-device-related complications. One additional patient died of Pseudomonas sepsis after staged cardiac transplantation. The remaining three patients are alive and have been followed up for as long as 2 years after staged cardiac transplantation. Of the two patients who were supported with the total artificial heart, one underwent staged cardiac transplantation after 11 days of support. Unfortunately, this patient succumbed to fungal sepsis 17 days later. The remaining patient, who received the total artificial heart after rejection of a transplanted heart, expired 379 days later before a suitable donor organ could be located. These experiences indicate that 1) the ventricular-assist pump and total artificial heart can provide reasonably safe effective circulatory support until a patient's overall physiological status is optimal, until a donor organ can be located for transplantation, or both; 2) there is a need for short-, intermediate-, and long-term support system capabilities; and 3) regardless of the patients' underlying pathology (ischemic versus nonischemic cardiomyopathy), in most instances, the simpler external ventricular-assist pump is capable of satisfactory hemodynamic circulatory assistance.

Acute Kidney Injury↗
PubMed1988

Development of smaller artificial ventricles and valves made by vacuum forming.

Implantable prosthetic ventricles and trileaflet valves made by vacuum forming have been developed and implant tested. All components are made from Pellethane. Recognizing the need for smaller as well as larger ventricles, designs with effective stroke volumes of 50, 85, 100 and 130 cc have been tested with several valve types. The pneumatically driven Utah ventricular assist device (UVAD) can be used as a total artificial heart (TAH) or ventricular assist device (VAD) by using the appropriate inflow and outflow adapters. In vitro durability testing has demonstrated ventricular lifetime beyond two years and valve lifetime to nearly one and one half years. The polymer valves have lower regurgitation than mechanical valves. Animal implantation experience includes 21 TAH implants and 16 left ventricular assist device (LVAD) implantations. TAH survival ranges from 2 to 210 days. LVAD animals have lived up to 116 days before elective termination. The animal were healthy and grew normally. The devices exhibit a "Starling's Law" response. One TAH animal survived 72 days before successful explantation followed by transplantation. At autopsy, this animal had no renal infarcts. Hematology data has demonstrated the existance of little or no intravascular hemolysis (PF Hb less than 5 mg%). The "Philadelphia" version of the UVAD vacuum formed ventricles are small enough to be implanted without thrombus provoking connectors. Eight animals have received this TAH and survived up to 120 days. Vacuum forming offers a rapid and inexpensive way to produce reliable and effective total artificial hearts and valves for widespread, temporary clinical application in any size adult human.

Animals↗
PubMedDate not supplied

Determinants of survival in patients with ventricular assist devices.

Mechanical ventricular assist devices (VADs) have led to survival in patients who develop postcardiotomy cardiogenic shock (PCCS) refractory to conventional therapies. To elicit determinants of survival, the authors reviewed records of 26 patients at our institution who required Pierce-Donachy VADs for PCCS. Thirteen patients were weaned from ventricular assistance (50%), nine (34.6%) achieved long-term survival, and 17 died. Survivors and those that died were equivalent in terms of age, sex, NYHA class, type of operation, and preoperative hemodynamics. Ventricular assist pumping was established earlier in survivors (P = 0.006) although aortic cross-clamp and total cardiopulmonary bypass times were equivalent between the groups. The development of biventricular failure was significantly associated with the inability to wean from mechanical circulatory assistance. Despite an equal incidence of biventricular failure, survivors had milder forms of this entity and all patients with severe biventricular failure requiring a biventricular assist device failed to wean and ultimately died (N = 5). Of all complications, inadequate cardiac output was a significant determinant of weaning. Perioperative myocardial infarction and renal failure were found to be univariate determinants of survival. Inadequate cardiac output and biventricular failure preclude weaning from mechanical circulatory assistance. Survival is associated with the expeditious establishment of assist pumping, and with the avoidance of irreversible perioperative myocardial injury and renal failure.

Acute Kidney Injury↗
PubMed1986

Percutaneous cardiopulmonary bypass and innovations in clinical counterpulsation.

This report points out the progress that has been made with cardiac support devices since they were first clinically applied in the mid-1960s. Advances in technology have allowed the development of PBY. Innovatively applied modifications of existing support systems have allowed patient survival when conventional systems could not be utilized. Continued refinements in design, materials, and power sources will allow circulatory assistance to progress as an extremely useful clinical tool for the treatment of patients with acute and chronic ventricular failure.

Adolescent↗