Alex Massiello | Case Western Reserve University (original) (raw)
Papers by Alex Massiello
PubMed, Jul 1, 1991
A poor fit will negate any physiologic evaluation of an implantable total artificial heart (TAH).... more A poor fit will negate any physiologic evaluation of an implantable total artificial heart (TAH). Fifteen Holstein calves (weight, 65-111 kg) were used to measure intrathoracic dimensions for TAH design, to find correlations between intrathoracic and external parameters for preoperative animal selection, and to suggest minor modifications for fitting a TAH in calf chests. The following dimensions were found to be critical to avoid compromising venous return: 1) mitral annulus center (MVC)-sternum, 10.4 +/- 1.0 cm; 2) tricuspid annulus center (TVC)-sternum, 9.8 +/- 1.6 cm; 3) MVC-TVC, 5.5 +/- 0.4 cm; 4) MVC-diaphragm, 3.4 +/- 0.8 cm; 5) MVC-left chest wall, 4.5 +/- 0.9 cm; and 6) TVC-right chest wall, 4.5 +/- 1.0 cm. These dimensions had no statistically significant correlation with body weight, but three of them did with the following external parameters: 1) bronchial carina-sternum on chest radiograph, p less than 0.05; 2) dorsoventral dimension at xiphoid, p less than 0.05; and 3) circumference at the caudal end of the scapula, p less than 0.05. Based on these results, the port orientation of the left housing of this electrohydraulic TAH designed for humans was modified for in vivo evaluation in calves. No other pump features required change. These data should prove useful to others involved in TAH development.
PubMed, Jul 1, 1990
An intrathoracic, electrohydraulically actuated, left ventricular assist system (LVAS) was subjec... more An intrathoracic, electrohydraulically actuated, left ventricular assist system (LVAS) was subjected to formal device readiness testing. Endurance testing was initiated on eight systems before testing was halted due to failure of four of the systems. Three failed due to environmental leakage. Solutions were straightforward, involving gasket changes and o-ring resizing. The fourth failure involved a magnetic coupling piston swelling and seizing. The failure was attributed, after long investigation, to hydrogen adsorption by the samarium-cobalt magnets. An unknown number of coupling magnets were affected in this fashion, necessitating complete replacement of magnets to resolve the problem. However, this was beyond the scope of the program, and no further endurance testing was accomplished. The test experience of the Nimbus/CCF LVAS has demonstrated all functional aspects of the complete LVAS, both in vitro and in vivo, and the endurance and reliability potential is indicated as well. Although the LVAS program is currently inactive, its legacy of technical innovations continue to drive the development of other medical devices.
Thoracic and Cardiovascular Surgeon, 2008
Objective: To evaluate the effects of replacing the titanium (Ti)stator housing in the DexAide ri... more Objective: To evaluate the effects of replacing the titanium (Ti)stator housing in the DexAide right ventricular assist device with one fabricated from biocompatible Zirconia oxide(Zr)ceramic. Methods: Pump hydraulic performance,journal bearing reliability,biocompatibility,and motor efficiency of the Zr stator were evaluated in vitro and in vivo (4 chronic bovine experiments) and compared with those using the Ti stator. Results: Compared with the Ti stator,the Zr stator showed increased battery life by 38% from 8 hours and 55 minutes on fully charged batteries at 2,500 rpm and 5.0 L/min to 12 hours and 20 minutes.In vitro hydraulic performance was unchanged with the exception of a 20% decrease in power consumption when using the Zr stator. Average in vivo pump flows and speeds using a Zr stator were comparable to the average values for 14 prior Ti stator in vivo studies with the exception of a 19% reduction in power consumption.Hemolysis and platelet aggregation tests were comparable for both stator types.Post explant evaluation of the Zr blood journal bearing surfaces showed no biologic deposition or signs of wear indicating favorable biocompatibility. Conclusions: The results of these studies showed that Zr ceramic can be used as a hemocompatible material to improve motor efficiency while maintaining hydraulic performance in a blood journal bearing application.
The Journal of Thoracic and Cardiovascular Surgery, Oct 1, 2008
Objective: Occlusion of the left atrial appendage is proposed to reduce the risk of stroke in pat... more Objective: Occlusion of the left atrial appendage is proposed to reduce the risk of stroke in patients with atrial fibrillation. The third-generation atrial exclusion device, modified to provide uniform distribution of pressure at appendage exclusion, was assessed for safety and effectiveness in a canine model and compared with a surgical stapler. Methods: The atrial exclusion device consists of 2 parallel, straight, rigid titanium tubes and 2 nitinol springs with a knit-braided polyester fabric. Fourteen mongrel dogs were implanted with the device at the base of the left atrial appendage via a median sternotomy. In each dog, the right atrial appendage was stapled with a commercial apparatus for comparison. The animals were evaluated at 7 days (n 5 3), 30 days (n 5 5), and 90 days (n 5 6) after implantation by epicardial echocardiography, left atrial and coronary angiography, gross pathology, and histology. Results: Left atrial appendage exclusion was complete and achieved without hemodynamic instability, and coronary angiography revealed that the left circumflex artery was patent in all cases. A new endothelial tissue layer developed on the occluded orifice of the left atrium 90 days after implantation. This endothelial layer was not evident on the stapled right atrial appendage. Conclusion: In dogs, the third-generation atrial exclusion device achieved easy, reliable, and safe exclusion of the left atrial appendage with favorable histologic results. Clinical application could provide a new therapeutic option for reducing the risk of stroke in patients with atrial fibrillation.
Asaio Journal, Apr 1, 1996
Asaio Journal, Mar 1, 1997
Asaio Journal, Mar 1, 1996
Asaio Journal, Mar 1, 2001
The Journal of Heart and Lung Transplantation, 2013
Purpose The incidence of percutaneous lead failure due to wear and traumatic fracture among patie... more Purpose The incidence of percutaneous lead failure due to wear and traumatic fracture among patients supported with a Heartmate (HM) II left ventricular assist device (LVAD) has not been previously reported. Methods and Materials The study is a retrospective review of all HM II LVAD percutaneous driveline malfunctions reported to Thoratec Corporation. Categorization of wear and failure by location and severity was performed and the incidence of adverse clinical outcomes as well as the management of the dysfunctional leads were examined. Results Between 2004 and October 2012, 12,969 HM II pumps were implanted worldwide. The incidence of percutaneous lead malfunction was 1,418 events occurring in 1,198 pumps (9.2%) over a cumulative support period of 13,932 patient-years (maximum = 7.3 years). Reported lead damage was mostly in the externalized part of the cable (87.2%). Lead malfunction was managed with external reinforcement in 7.5% of the implanted pumps, while mortality or significant morbidity including pump exchange or urgent transplant, or more complex end-cable replacement occurred in 2.3%. Percutaneous lead malfunction not associated with adverse events was managed by clamshell reinforcement of the connector strain relief or by tape/silicone cable reinforcement. The cumulative incidence of internal lead failures has decreased with two lead design revisions: 1.6% in 2004 (original design) vs. 0.01% in 2010 (redesigned internal pump end bend relief). Conclusions The incidence of HM II percutaneous lead malfunction associated with serious adverse events is low and the majority of patients who experience lead damage have been successfully managed by external repairs. The incidence of both internal and external lead failures has diminished since 2004 with progressive iterations and improvements in lead design.
ASAIO transactions / American Society for Artificial Internal Organs
A completely implantable total artificial heart (TAH) is being developed based on many years of r... more A completely implantable total artificial heart (TAH) is being developed based on many years of research performed at the Cleveland Clinic Foundation and Nimbus, Inc. The pumping unit consists of biolized surface-treated pusher plate blood pumps powered by an interventricular electrohydraulic energy converter. A variable volume device references the back side of the pusher plates to lung pressure. Electrical power is supplied by a transcutaneous energy transmission system, integrated with a wearable external battery pack. An implanted internal battery provides back-up power. System design and optimization efforts have resulted in a compact pumping unit package and an overall TAH that meets anatomic, physiologic, and engineering requirements. Overall pumping unit basic dimensions are 98 mm diameter and 80 mm thick. The blood pumps have a truncated conical shape and are separated by a thin interventricular septum 21 mm thick. Theoretical stroke volume is 64 ml, and maximum stroke leng...
Una bomba de sangre para el bombeo de dos corrientes de sangre, que comprende: una carcasa (40, 5... more Una bomba de sangre para el bombeo de dos corrientes de sangre, que comprende: una carcasa (40, 50); un estator (860) soportado en la carcasa; y un conjunto de rotor que comprende un rotor (880) soportado en la carcasa para su giro con relacion al estator (860) alrededor de un eje (852); una primera etapa de bombeo centrifugo que incluye un primer impulsor (34) funcionalmente acoplado a un primer extremo axial del rotor para su giro con el rotor alrededor del eje, y una segunda etapa de bombeo centrifugo que incluye un segundo impulsor (36) funcionalmente acoplado a un segundo extremo axial del rotor, opuesto al primer extremo axial, para su giro con el rotor alrededor del eje, comprendiendo el estator (860) un nucleo de estator (868); una primera laminacion (862) bobinada alrededor de una parte axial del nucleo del estator y una segunda laminacion (862) bobinada alrededor de una segunda parte axial del nucleo del estator (868), estando espaciadas la primera y segunda laminaciones (...
The Journal of Thoracic and Cardiovascular Surgery
Circulation, Oct 28, 2008
PubMed, Jul 1, 1991
A poor fit will negate any physiologic evaluation of an implantable total artificial heart (TAH).... more A poor fit will negate any physiologic evaluation of an implantable total artificial heart (TAH). Fifteen Holstein calves (weight, 65-111 kg) were used to measure intrathoracic dimensions for TAH design, to find correlations between intrathoracic and external parameters for preoperative animal selection, and to suggest minor modifications for fitting a TAH in calf chests. The following dimensions were found to be critical to avoid compromising venous return: 1) mitral annulus center (MVC)-sternum, 10.4 +/- 1.0 cm; 2) tricuspid annulus center (TVC)-sternum, 9.8 +/- 1.6 cm; 3) MVC-TVC, 5.5 +/- 0.4 cm; 4) MVC-diaphragm, 3.4 +/- 0.8 cm; 5) MVC-left chest wall, 4.5 +/- 0.9 cm; and 6) TVC-right chest wall, 4.5 +/- 1.0 cm. These dimensions had no statistically significant correlation with body weight, but three of them did with the following external parameters: 1) bronchial carina-sternum on chest radiograph, p less than 0.05; 2) dorsoventral dimension at xiphoid, p less than 0.05; and 3) circumference at the caudal end of the scapula, p less than 0.05. Based on these results, the port orientation of the left housing of this electrohydraulic TAH designed for humans was modified for in vivo evaluation in calves. No other pump features required change. These data should prove useful to others involved in TAH development.
PubMed, Jul 1, 1990
An intrathoracic, electrohydraulically actuated, left ventricular assist system (LVAS) was subjec... more An intrathoracic, electrohydraulically actuated, left ventricular assist system (LVAS) was subjected to formal device readiness testing. Endurance testing was initiated on eight systems before testing was halted due to failure of four of the systems. Three failed due to environmental leakage. Solutions were straightforward, involving gasket changes and o-ring resizing. The fourth failure involved a magnetic coupling piston swelling and seizing. The failure was attributed, after long investigation, to hydrogen adsorption by the samarium-cobalt magnets. An unknown number of coupling magnets were affected in this fashion, necessitating complete replacement of magnets to resolve the problem. However, this was beyond the scope of the program, and no further endurance testing was accomplished. The test experience of the Nimbus/CCF LVAS has demonstrated all functional aspects of the complete LVAS, both in vitro and in vivo, and the endurance and reliability potential is indicated as well. Although the LVAS program is currently inactive, its legacy of technical innovations continue to drive the development of other medical devices.
Thoracic and Cardiovascular Surgeon, 2008
Objective: To evaluate the effects of replacing the titanium (Ti)stator housing in the DexAide ri... more Objective: To evaluate the effects of replacing the titanium (Ti)stator housing in the DexAide right ventricular assist device with one fabricated from biocompatible Zirconia oxide(Zr)ceramic. Methods: Pump hydraulic performance,journal bearing reliability,biocompatibility,and motor efficiency of the Zr stator were evaluated in vitro and in vivo (4 chronic bovine experiments) and compared with those using the Ti stator. Results: Compared with the Ti stator,the Zr stator showed increased battery life by 38% from 8 hours and 55 minutes on fully charged batteries at 2,500 rpm and 5.0 L/min to 12 hours and 20 minutes.In vitro hydraulic performance was unchanged with the exception of a 20% decrease in power consumption when using the Zr stator. Average in vivo pump flows and speeds using a Zr stator were comparable to the average values for 14 prior Ti stator in vivo studies with the exception of a 19% reduction in power consumption.Hemolysis and platelet aggregation tests were comparable for both stator types.Post explant evaluation of the Zr blood journal bearing surfaces showed no biologic deposition or signs of wear indicating favorable biocompatibility. Conclusions: The results of these studies showed that Zr ceramic can be used as a hemocompatible material to improve motor efficiency while maintaining hydraulic performance in a blood journal bearing application.
The Journal of Thoracic and Cardiovascular Surgery, Oct 1, 2008
Objective: Occlusion of the left atrial appendage is proposed to reduce the risk of stroke in pat... more Objective: Occlusion of the left atrial appendage is proposed to reduce the risk of stroke in patients with atrial fibrillation. The third-generation atrial exclusion device, modified to provide uniform distribution of pressure at appendage exclusion, was assessed for safety and effectiveness in a canine model and compared with a surgical stapler. Methods: The atrial exclusion device consists of 2 parallel, straight, rigid titanium tubes and 2 nitinol springs with a knit-braided polyester fabric. Fourteen mongrel dogs were implanted with the device at the base of the left atrial appendage via a median sternotomy. In each dog, the right atrial appendage was stapled with a commercial apparatus for comparison. The animals were evaluated at 7 days (n 5 3), 30 days (n 5 5), and 90 days (n 5 6) after implantation by epicardial echocardiography, left atrial and coronary angiography, gross pathology, and histology. Results: Left atrial appendage exclusion was complete and achieved without hemodynamic instability, and coronary angiography revealed that the left circumflex artery was patent in all cases. A new endothelial tissue layer developed on the occluded orifice of the left atrium 90 days after implantation. This endothelial layer was not evident on the stapled right atrial appendage. Conclusion: In dogs, the third-generation atrial exclusion device achieved easy, reliable, and safe exclusion of the left atrial appendage with favorable histologic results. Clinical application could provide a new therapeutic option for reducing the risk of stroke in patients with atrial fibrillation.
Asaio Journal, Apr 1, 1996
Asaio Journal, Mar 1, 1997
Asaio Journal, Mar 1, 1996
Asaio Journal, Mar 1, 2001
The Journal of Heart and Lung Transplantation, 2013
Purpose The incidence of percutaneous lead failure due to wear and traumatic fracture among patie... more Purpose The incidence of percutaneous lead failure due to wear and traumatic fracture among patients supported with a Heartmate (HM) II left ventricular assist device (LVAD) has not been previously reported. Methods and Materials The study is a retrospective review of all HM II LVAD percutaneous driveline malfunctions reported to Thoratec Corporation. Categorization of wear and failure by location and severity was performed and the incidence of adverse clinical outcomes as well as the management of the dysfunctional leads were examined. Results Between 2004 and October 2012, 12,969 HM II pumps were implanted worldwide. The incidence of percutaneous lead malfunction was 1,418 events occurring in 1,198 pumps (9.2%) over a cumulative support period of 13,932 patient-years (maximum = 7.3 years). Reported lead damage was mostly in the externalized part of the cable (87.2%). Lead malfunction was managed with external reinforcement in 7.5% of the implanted pumps, while mortality or significant morbidity including pump exchange or urgent transplant, or more complex end-cable replacement occurred in 2.3%. Percutaneous lead malfunction not associated with adverse events was managed by clamshell reinforcement of the connector strain relief or by tape/silicone cable reinforcement. The cumulative incidence of internal lead failures has decreased with two lead design revisions: 1.6% in 2004 (original design) vs. 0.01% in 2010 (redesigned internal pump end bend relief). Conclusions The incidence of HM II percutaneous lead malfunction associated with serious adverse events is low and the majority of patients who experience lead damage have been successfully managed by external repairs. The incidence of both internal and external lead failures has diminished since 2004 with progressive iterations and improvements in lead design.
ASAIO transactions / American Society for Artificial Internal Organs
A completely implantable total artificial heart (TAH) is being developed based on many years of r... more A completely implantable total artificial heart (TAH) is being developed based on many years of research performed at the Cleveland Clinic Foundation and Nimbus, Inc. The pumping unit consists of biolized surface-treated pusher plate blood pumps powered by an interventricular electrohydraulic energy converter. A variable volume device references the back side of the pusher plates to lung pressure. Electrical power is supplied by a transcutaneous energy transmission system, integrated with a wearable external battery pack. An implanted internal battery provides back-up power. System design and optimization efforts have resulted in a compact pumping unit package and an overall TAH that meets anatomic, physiologic, and engineering requirements. Overall pumping unit basic dimensions are 98 mm diameter and 80 mm thick. The blood pumps have a truncated conical shape and are separated by a thin interventricular septum 21 mm thick. Theoretical stroke volume is 64 ml, and maximum stroke leng...
Una bomba de sangre para el bombeo de dos corrientes de sangre, que comprende: una carcasa (40, 5... more Una bomba de sangre para el bombeo de dos corrientes de sangre, que comprende: una carcasa (40, 50); un estator (860) soportado en la carcasa; y un conjunto de rotor que comprende un rotor (880) soportado en la carcasa para su giro con relacion al estator (860) alrededor de un eje (852); una primera etapa de bombeo centrifugo que incluye un primer impulsor (34) funcionalmente acoplado a un primer extremo axial del rotor para su giro con el rotor alrededor del eje, y una segunda etapa de bombeo centrifugo que incluye un segundo impulsor (36) funcionalmente acoplado a un segundo extremo axial del rotor, opuesto al primer extremo axial, para su giro con el rotor alrededor del eje, comprendiendo el estator (860) un nucleo de estator (868); una primera laminacion (862) bobinada alrededor de una parte axial del nucleo del estator y una segunda laminacion (862) bobinada alrededor de una segunda parte axial del nucleo del estator (868), estando espaciadas la primera y segunda laminaciones (...
The Journal of Thoracic and Cardiovascular Surgery
Circulation, Oct 28, 2008