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Tofy Mussivand

Publications and source records attributed to Tofy Mussivand.

13 recordsLinked to original sources
PubMed2006

Development of a mathematical model of the human circulatory system.

A mathematical lumped parameter model of the human circulatory system (HCS) has been developed to complement in vitro testing of ventricular assist devices. Components included in this model represent the major parts of the systemic HCS loop, with all component parameters based on physiological data available in the literature. Two model configurations are presented in this paper, the first featuring elements with purely linear constitutive relations, and the second featuring nonlinear constitutive relations for the larger vessels. Three different aortic compliance functions are presented, and a pressure-dependent venous flow resistance is used to simulate venous collapse. The mathematical model produces reasonable systemic pressure and flow behaviour, and graphs of this data are included.

Cardiovascular Physiological Phenomena↗
PubMed2004

Clinical results with an ePTFE inflow conduit for mechanical circulatory support.

BACKGROUND: Neurologic complication is an adverse event associated with mechanical circulatory support. To decrease the incidence of embolic cerebrovascular accidents (CVA) during support with the Novacor left ventricular assist system (LVAS), an expanded polytetrafluoroethylene (ePTFE) inflow conduit has been developed and introduced clinically. METHODS: Using clinical data from Europe and Canada, we conducted a retrospective analysis of the incidence of embolic CVA with the ePTFE inflow conduit (n=88) in comparison with the previously used polyester inflow conduits (n=310, including Vascutek n=155 and Cooley n=155). We calculated freedom from embolic CVA, risk reduction for embolic CVA, and linearized rates of embolic CVA. RESULTS: A significant decrease in the incidence of embolic CVA was demonstrated with the ePTFE conduit (ePTFE 10% vs polyester 23%, p=0.002). Kaplan-Meier analysis of freedom from embolic CVA at 180 days after implantation was 86% for the ePTFE group vs 72% for the polyester group (log-rank test, 0.0185). We also found an associated risk reduction of 55% in CVA occurrence in the ePTFE group when compared with the Polyester group (hazard ratio, 0.445; 95% confidence limit, 0.222-0.890; p=0.0221). Linearized CVA rates also were decreased at all time intervals after implantation in the ePTFE group. CONCLUSIONS: Preliminary clinical results with the newly introduced ePTFE inflow conduit provide compelling evidence that the ePTFE conduit material significantly decreases thromboembolic complications during mechanical circulatory support with the Novacor LVAS.

Adolescent↗
PubMed2004

Patient selection for left ventricular assist devices.

The use of mechanical support as a bridge to cardiac transplant has become the standard of care in many cardiac transplant centers. This therapy has been shown to increase survival and improve morbidity in carefully selected patients waiting for heart transplantation. With approximately 30000 patients being listed worldwide for transplant every year and only 3500 transplantations performed annually, alternative strategies need to be developed to minimize morbidity and mortality in this high-risk population. Patient selection remains the primary determinant of success with left ventricular assist device (LVAD) therapy. This article will review both the cardiac and extracardiac considerations needed in the assessment of patient suitability for LVAD support as a bridge to transplantation.

Body Constitution↗
PubMed2004

Under-utilization of mechanical circulatory support in Canada: why and what can be done?

In October of 2002, a workshop was held as part of the Canadian Cardiovascular Congress in Edmonton, Canada, entitled "Under-Utilization of Mechanical Circulatory Support in Canada. Why and What Can Be Done?" The workshop examined various issues related to the use of mechanical circulatory support devices in the Canadian context. Representatives from all Canadian centers with active mechanical circulatory support programs were invited to participate and participants included surgeons and cardiologists, as well as other affiliated health professionals. Opinions were solicited from the workshop participants and a series of recommendations were formulated.

Assisted Circulation↗
PubMed2003

Mechanical circulatory support for adolescent patients: the Ottawa Heart Institute experience.

BACKGROUND: Mechanical circulatory support devices may be used for patients with end-stage heart failure for bridging either to cardiac transplant or to recovery of the native heart. While less common in adolescents, fulminant heart failure may be rapidly fatal in these patients unless circulatory support can be instituted. OBJECTIVES: To assess the outcomes and the utility of mechanical circulatory assist devices for children. METHODS: A retrospective review of pediatric patients (18 years of age or younger) who underwent circulatory support at the Ottawa Heart Institute, Ottawa, Ontario, from 1992 to 2001 was performed using chart audits. RESULTS: Seven patients (four boys, three girls) with a mean age of 14.9 +/- 0.9 years were supported with Thoratec ventricular assist devices (n=6) or a CardioWest total artificial heart (n=1). Preoperatively, the cardiac index was 1.64 +/- 0.2 L/min/m2 on one or two inotropes with ejection fractions of 11 +/- 2.2%. Mean duration of circulatory support was 59.3 +/- 17.2 days with a hospital length of stay of 89.6 +/- 12.8 days. All seven patients underwent successful transplantation and were discharged home. CONCLUSIONS: Pediatric patients with fulminant heart failure may be bridged to cardiac transplant successfully with mechanical circulatory support devices.

Adolescent↗
PubMed2003

Honoring living legends.

From August 17 to 19, 2001, the University of Ottawa Heart Institute hosted the 6th Symposium of the World Artificial-Organ, Immunology and Transplantation Society (WAITS 2001). During WAITS 2001 a very special session entitled "Living Legends-Lessons Learned and Future Visions" was held. This session brought together giants in the field who had pioneered organ transplantation, cardiovascular surgery, pacemakers, and artificial hearts, among many other major contributions. The purpose of the session was to both honor and learn from those who have contributed greatly to the major scientific and technological advances in our field during the twentieth century.

Animals↗
PubMedDate not supplied

Is center specific implantation volume a predictor of clinical outcomes with mechanical circulatory support?

This study examined the relationship between implant center volumes and survival rate for implantation of mechanical circulatory support (MCS) devices. Using the Novacor left ventricular assist system (LVAS) Registry, the study cohort consisted of 1,348 patients with established outcomes from 97 centers stratified by the implant center volume: 1-10 implants (n = 199, 65 centers), 11-25 implants (n = 189, 12 centers), 26-50 implants (n = 445, 13 centers), and more than 51 implants (n = 515, 7 centers). Regression and correlation analyses were performed. Regression analysis found a negative impact on survival for centers performing 1-10 implants, with an odds ratio of 1.73 (95% confidence interval, 1.28-2.34; p < 0.001). Composite results from the first 10 implants of each larger volume center were then compared with the group with 1-10 implants, demonstrating that centers with larger volumes had superior results, even in the early patient experience (61% versus 46% transplanted/weaned, p < 0.001). However, when annualized outcomes (i.e., outcomes by calendar year) were determined for each center, no significant correlation was found between the outcomes and annualized frequency of implantation (R2 = 0.003, n = 422). Although the total number of implants performed at a specific center appeared to impact clinical outcomes, no correlation was found between annualized frequency of implant and clinical outcome.

Adolescent↗
PubMedDate not supplied

Virtual anatomical three-dimensional fit trial for intra-thoracically implanted medical devices.

Our purpose is to develop a system that converts computed tomography (CT) scans into an interactive three-dimensional (3-D) model of the thoracic cavity. This study will allow for the preoperative determination of optimal anatomical fit of intra-thoracically implanted medical equipment such as circulatory support devices. From the radiology data bank, we consecutively selected 34 cardiac and 42 noncardiac patients who had CT scans of the chest. Anatomical structures of the electronic CT scans were manually extracted using software. These structures included the thoracic cage, lungs, heart, and the great vessels. The information was converted into a 3-D surface mesh model, which was imported into a 3-D viewer to acquire direct anatomical measurements. The thoracic cage and intra-thoracic organs were measured for data analysis. A methodology was successfully developed to convert a patient's thoracic CT scans into interactive 3-D models, permitting the collection of key anatomical measurements to assess intra-thoracic device fit feasibility. Extensive measurements of the reconstructed thoracic cavity were recorded in a database format and analyzed. This study demonstrated the feasibility of implementing a rapid preoperative screening method based on anatomical fit for the selection or rejection of patients who are candidates for an intra-thoracic mechanical device. This new method will allow for the virtual preoperative implantation of such devices within a patient's chest cavity.

Aged↗
PubMedDate not supplied

Left ventricular assist devices as bridge to heart transplantation in congestive heart failure with pulmonary hypertension.

Severe pulmonary hypertension (PH) has been considered a significant contraindication to cardiac transplantation. Ongoing clinical experience, however, has shown that temporary support using left ventricular assist devices (LVADs) in these patients can result in significant reductions in PH. A comprehensive review of the available literature regarding the use of LVADs in heart failure patients with PH was conducted. The existing literature to date supports the use of LVADs in heart failure patients with PH and demonstrates that significant reductions in PH in these patients can be achieved. This subsequently allows for safe and effective cardiac transplantation in patients who were previously excluded from this modality. For heart failure patients with severe PH, the use of LVADs can provide significant benefits by significantly reducing PH and allowing subsequent staged transplantation.

Heart Failure↗
PubMedDate not supplied

In vivo evaluation of the biocompatibility of the totally implantable ventricular assist device (HeartSaver VAD).

A series of multicenter in vivo studies have been conducted to assess the biocompatibility and device performance of the HeartSaver VAD, a totally implantable pulsatile ventricular assist device (VAD). The experiments (n = 23) were conducted in calves with a mean weight of 101 (75-152) kg. Implants took place at four centers using two different surgical procedures of implantation (one with cardiopulmonary bypass and one without). Three anticoagulation regimens were used (one with continuous intravenous heparin, one with oral warfarin, and one with oral warfarin combined with antiplatelet clopidogrel therapy). Device function and biochemistry were monitored during the study, and organs and device analysis were conducted at explant. There were six nonsurvivors because of early surgical complications (during the first week of support). The postoperative courses in the remaining 17 (74%) calves were uneventful. Hemodynamic and biocompatibility indicators were monitored throughout the study. The mean duration of device support for those cases was 48 (13-92) days. Mean device flow was 7.15 (+/- 1.68) L/min. There were no deaths caused by infection; however, two animals developed endocarditis believed to be caused by the percutaneous instrumentation lines used for the study. No severe bleeding requiring reoperation occurred during the study. The mean plasma free hemoglobin was within normal limits at 6.8 +/- 2.6 mg/dl. Renal and hepatic functions were normal with a mean creatinine of 0.6 +/- 0.1 mg/dl and a mean aspartate aminotransferase of 68.7 +/- 42.6 mg/dl. Several device related improvements were identified and have now been implemented. Additional bovine implants with an optimized device are currently underway in preparation for human trials.

Animals↗