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The Journal of Surgical Research Dec 2015We tested the short-term effects of completely nonpulsatile versus pulsatile circulation after ventricular excision and replacement with total implantable pumps in an... (Comparative Study)
Comparative Study
BACKGROUND
We tested the short-term effects of completely nonpulsatile versus pulsatile circulation after ventricular excision and replacement with total implantable pumps in an animal model on peripheral vascular permeability.
METHODS
Ten calves underwent cardiac replacement with two HeartMate III continuous-flow rotary pumps. In five calves, the pump speed was rapidly modulated to impart a low-frequency pulse pressure in the physiologic range (10-25 mm Hg) at a rate of 40 pulses per minute (PP). The remaining five calves were supported with a pulseless systemic circulation and no modulation of pump speed (NP). Skeletal muscle biopsies were obtained before cardiac replacement (baseline) and on postoperative days (PODs) 1, 7, and 14. Skeletal muscle-tissue water content was measured, and morphologic alterations of skeletal muscle were assessed. VE-cadherin, phospho-VE-cadherin, and CD31 were analyzed by immunohistochemistry.
RESULTS
There were no significant changes in tissue water content and skeletal muscle morphology within group or between groups at baseline, PODs 1, 7, and 14, respectively. There were no significant alterations in the expression and/or distribution of VE-cadherin, phospho-VE-cadherin, and CD31 in skeletal muscle vasculature at baseline, PODs 1, 7, and 14 within each group or between the two groups, respectively. Although continuous-flow total artificial heart (CFTAH) with or without a pulse pressure caused slight increase in tissue water content and histologic damage scores at PODs 7 and 14, it failed to reach statistical significance.
CONCLUSIONS
There was no significant adherens-junction protein degradation and phosphorylation in calf skeletal muscle microvasculature after CFTAH implantation, suggesting that short term of CFTAH with or without pulse pressure did not cause peripheral endothelial injury and did not increase the peripheral microvascular permeability.
Topics: Adherens Junctions; Animals; Antigens, CD; Cadherins; Capillary Permeability; Cattle; Edema; Endothelium, Vascular; Female; Heart, Artificial; Hemorheology; Male; Microvessels; Muscle, Skeletal
PubMed: 26188957
DOI: 10.1016/j.jss.2015.06.035 -
The Annals of Thoracic Surgery Jan 2013With implantable cardiac assist devices increasingly proving their effectiveness as therapeutic options for end-stage heart failure, it is important for clinicians to... (Review)
Review
With implantable cardiac assist devices increasingly proving their effectiveness as therapeutic options for end-stage heart failure, it is important for clinicians to understand the unique physiology of device-assisted circulation. Preload sensitivity as it relates to cardiac assist devices is derived from the Frank-Starling relationship between human ventricular filling pressures and ventricular stroke volume. In this review, we stratify the preload sensitivity of 17 implantable cardiac assist devices relative to the native heart and discuss the effect of preload sensitivity on left ventricular volume unloading, levels of cardiac support, and the future development of continuous-flow total artificial heart technology.
Topics: Equipment Design; Heart Failure; Heart-Assist Devices; Humans; Ventricular Pressure
PubMed: 23272869
DOI: 10.1016/j.athoracsur.2012.07.077 -
Journal of Cardiac Surgery Dec 2022There continues to be an unmet therapeutic need for an alternative treatment strategy for respiratory distress and lung disease. We are developing a portable...
There continues to be an unmet therapeutic need for an alternative treatment strategy for respiratory distress and lung disease. We are developing a portable cardiopulmonary support system that integrates an implantable oxygenator with a hybrid, dual-support, continuous-flow total artificial heart (TAH). The TAH has a centrifugal flow pump that is rotating about an axial flow pump. By attaching the hollow fiber bundle of the oxygenator to the base of the TAH, we establish a new cardiopulmonary support technology that permits a patient to be ambulatory during usage. In this study, we investigated the design and improvement of the blood flow pathway from the inflow-to-outflow of four oxygenators using a mathematical model and computational fluid dynamics (CFD). Pressure loss and gas transport through diffusion were examined to assess oxygenator design. The oxygenator designs led to a resistance-driven pressure loss range of less than 35 mmHg for flow rates of 1-7 L/min. All of the designs met requirements. The configuration having an outside-to-inside blood flow direction was found to have higher oxygen transport. Based on this advantageous flow direction, two designs (Model 1 and 3) were then integrated with the axial-flow impeller of the TAH for simulation. Flow rates of 1-7 L/min and speeds of 10,000-16,000 RPM were analyzed. Blood damage studies were performed, and Model 1 demonstrated the lowest potential for hemolysis. Future work will focus on developing and testing a physical prototype for integration into the new cardiopulmonary assist system.
Topics: Humans; Equipment Design; Oxygenators; Heart, Artificial; Hemodynamics
PubMed: 36403254
DOI: 10.1111/jocs.17210 -
Physiological Research Nov 2020Extracorporeal life support (ECLS) is a treatment modality that provides prolonged blood circulation, gas exchange and can partially support or fully substitute... (Review)
Review
Extracorporeal life support (ECLS) is a treatment modality that provides prolonged blood circulation, gas exchange and can partially support or fully substitute functions of heart and lungs in patients with severe but potentially reversible cardiopulmonary failure refractory to conventional therapy. Due to high-volume bypass, the extracorporeal flow is interacting with native cardiac output. The pathophysiology of circulation and ECLS support reveals significant effects on arterial pressure waveforms, cardiac hemodynamics, and myocardial perfusion. Moreover, it is still subject of research, whether increasing stroke work caused by the extracorporeal flow is accompanied by adequate myocardial oxygen supply. The left ventricular (LV) pressure-volume mechanics are reflecting perfusion and loading conditions and these changes are dependent on the degree of the extracorporeal blood flow. By increasing the afterload, artificial circulation puts higher demands on heart work with increasing myocardial oxygen consumption. Further, this can lead to LV distention, pulmonary edema, and progression of heart failure. Multiple methods of LV decompression (atrial septostomy, active venting, intra-aortic balloon pump, pulsatility of flow) have been suggested to relieve LV overload but the main risk factors still remain unclear. In this context, it has been recommended to keep the rate of circulatory support as low as possible. Also, utilization of detailed hemodynamic monitoring has been suggested in order to avoid possible harm from excessive extracorporeal flow.
Topics: Adaptation, Physiological; Extracorporeal Membrane Oxygenation; Heart; Heart Failure; Heart-Assist Devices; Hemodynamics; Humans
PubMed: 32901493
DOI: 10.33549/physiolres.934332 -
Swiss Medical Weekly 2013In chronic cardiomyopathy, mechanical circulatory support plays an increasingly important role for children as the shortage of suitable donor hearts increases times on... (Review)
Review
In chronic cardiomyopathy, mechanical circulatory support plays an increasingly important role for children as the shortage of suitable donor hearts increases times on the transplant waiting list. Ventricular assist devices (VADs) for adults have evolved dramatically over the last decade, both as a bridge to transplantation and for permanent support. In contrast, VADs designed for children, especially for all age groups, are still in their infancy. The Medos HIA and the Berlin Heart Excor are specially designed for children with a body surface area <1.2 m2. Increased experience with existing paediatric VADs and the introduction of third-generation VADs for the paediatric age group offer new possibilities for children suffering from end-stage heart failure. We review the literature on this topic, summarise the indications and contraindications for long-term support VADs and describe the decision-making algorithm used at our institution for use of long-term VADs in children.
Topics: Cardiomyopathies; Child; Equipment Design; Heart Failure; Heart Transplantation; Heart, Artificial; Heart-Assist Devices; Humans; Pediatrics
PubMed: 23740078
DOI: 10.4414/smw.2013.13804 -
The Journal of Heart and Lung... Sep 2023Reduced arterial pulsatility in continuous-flow left ventricular assist devices (CF-LVAD) patients has been implicated in clinical complications. Consequently, recent...
BACKGROUND
Reduced arterial pulsatility in continuous-flow left ventricular assist devices (CF-LVAD) patients has been implicated in clinical complications. Consequently, recent improvements in clinical outcomes have been attributed to the "artificial pulse" technology inherent to the HeartMate3 (HM3) LVAD. However, the effect of the "artificial pulse" on arterial flow, transmission of pulsatility into the microcirculation and its association with LVAD pump parameters is not known.
METHODS
The local flow oscillation (pulsatility index, PI) of common carotid arteries (CCAs), middle cerebral arteries (MCAs) and central retinal arteries (CRAs-representing the microcirculation) were quantified by 2D-aligned, angle-corrected Doppler ultrasound in 148 participants: healthy controls, n = 32; heart failure (HF), n = 43; HeartMate II (HMII), n = 32; HM3, n = 41.
RESULTS
In HM3 patients, 2D-Doppler PI in beats with "artificial pulse" and beats with "continuous-flow" was similar to that of HMII patients across the macro- and microcirculation. Additionally, peak systolic velocity did not differ between HM3 and HMII patients. Transmission of PI into the microcirculation was higher in both HM3 (during the beats with "artificial pulse") and in HMII patients compared with HF patients. LVAD pump speed was inversely associated with microvascular PI in HMII and HM3 (HMII, r = 0.51, p < 0.0001; HM3 "continuous-flow," r = 0.32, p = 0.0009; HM3 "artificial pulse," r = 0.23, p = 0.007), while LVAD pump PI was only associated with microcirculatory PI in HMII patients.
CONCLUSIONS
The "artificial pulse" of the HM3 is detectable in the macro- and microcirculation but without creating a significant alteration in PI compared with HMII patients. Increased transmission of pulsatility and the association between pump speed and PI in the microcirculation indicate that the future clinical care of HM3 patients may involve individualized pump settings according to the microcirculatory PI in specific end-organs.
Topics: Humans; Microcirculation; Heart-Assist Devices; Heart Failure; Heart Rate; Middle Cerebral Artery
PubMed: 37098374
DOI: 10.1016/j.healun.2023.04.002 -
Medical Science Monitor Basic Research Sep 2015The totally artificial heart (TAH) is among the most prominent medical innovations of the 21st century, especially due to the increasing population with end-stage heart... (Review)
Review
The totally artificial heart (TAH) is among the most prominent medical innovations of the 21st century, especially due to the increasing population with end-stage heart failure. The progressive course of the disease, its resistance to conventional therapy, and the scarcity of hearts available for transplantation were the prime impetus for developing a TAH, especially when other options of mechanical circulatory assist devices are exhausted. In this review, we narrate the history of TAH, give an overview of its technology, and address the pros and cons of the currently available TAH models in light of published clinical experience.
Topics: Heart Diseases; Heart Transplantation; Heart, Artificial; Humans; Prosthesis Design
PubMed: 26343363
DOI: 10.12659/MSMBR.895418 -
The Journal of Thoracic and... Mar 2020
Topics: Child; Heart, Artificial; Humans
PubMed: 31610962
DOI: 10.1016/j.jtcvs.2019.08.067 -
BMJ (Clinical Research Ed.) Apr 1989
Topics: Assisted Circulation; Biomedical Research; Federal Government; Heart, Artificial; Heart-Assist Devices; Humans; Research Support as Topic; Risk Assessment; United States
PubMed: 2497815
DOI: 10.1136/bmj.298.6677.843 -
The Journal of Thoracic and... Mar 2020We have developed a new method of total artificial heart (TAH) support for young patients, and here share our preliminary results and evolving understanding.
BACKGROUND
We have developed a new method of total artificial heart (TAH) support for young patients, and here share our preliminary results and evolving understanding.
METHODS
This report is a retrospective chart review of all patients <10 kg who received a TAH at our institution from May 2017 to the time of this report.
RESULTS
Our cohort includes 5 patients. Two had single-ventricle circulation, 1 of whom had undergone a Glenn procedure and was revised back to a Sano shunt. Four were on extracorporeal life support for longer than 10 days, 3 with an open chest. In these 3 patients, the TAH was a salvage operation. Centrifugal pumps were used for 2 patients and pulsatile pumps for 3 patients. Three patients survived to transplantation and discharge, with support times of 79, 44, and 96 days; in these patients, the duration of follow-up from discharge to the time of this report was 687, 19, and 8 days, respectively, and all patients were well. For the pulsatile pumps, in the first patient we placed valved conduits for inflow connections. For the second patient, we omitted the valved conduits and oversized the pumps to avoid full fill; yet, despite our best efforts, full fill occurred frequently, and thus we converted to a systemic centrifugal pump.
CONCLUSIONS
Our method of TAH support can be tailored to provide effective support of carefully selected young children with single or biventricular physiology. In our opinion, for pulsatile pumps, oversizing the pump and using valved inflow conduits may be important adjuncts to achieve effective support.
Topics: Age Factors; Body Weight; Heart Defects, Congenital; Heart, Artificial; Humans; Infant; Infant, Newborn; Prosthesis Design; Prosthesis Implantation; Recovery of Function; Retrospective Studies; Time Factors; Treatment Outcome; Wisconsin
PubMed: 31669029
DOI: 10.1016/j.jtcvs.2019.09.063