Artificial organs
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Particulate embolization remains a serious complication of cardiac surgery. Adverse events associated with particulate embolization affect patient morbidity and long-term survival, and increase the length of hospital stay and the cost of health care. Today, atherosclerosis plays a role in at least two-thirds of all adverse events after coronary artery revascularization, and postoperative stroke is the second most common cause of operative mortality. ⋯ Patients must be carefully assessed before surgery to determine their risk, and if the risk is high, surgeons should consider using newer, innovative devices, and techniques in their operative strategy that have proven to be effective in mitigating some of the potential embolic adverse events. A multifaceted, preventive strategy can make a difference, not only in reducing particulate emboli, but also in reducing morbidity and in lowering the economic burden on the health-care system. This brief review will address three areas of focus that are important for the prevention of particulate embolization: (i) prevalence and morbidity of atherosclerotic disease; (ii) risk factors for adverse neurologic events; and (iii) prevention/mitigation of adverse events for patients undergoing cardiac surgery.
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Randomized Controlled Trial
Nitric oxide in conjunction with milrinone better stabilized pulmonary hemodynamics after Fontan procedure.
Inhaled nitric oxide (iNO) has been used for patients with increased pulmonary vascular resistance (PVR) shortly after Fontan operation, but repeat deterioration of PVR during or shortly after its withdrawal remains a major concern. Milrinone, a phosphodiesterase type 3 (PDE3) inhibitor, can also reduce PVR for postoperative patients with pulmonary hypertension. We hypothesized that iNO, in conjunction with milrinone, can provide additive benefits for pulmonary hemodynamics and reduce the occurrence of iNO withdrawal failure/rebound. ⋯ Combined application of iNO and milrinone resulted in (i) more significant decrement of CVP (19.6 +/- 3.5% in group iNO + Mil vs. 15.2 +/- 4.6% in group iNO, P < 0.05) and TPG (18.2 +/- 4.8% in group iNO + Mil vs. 15.3 +/- 2.6% in group iNO, P < 0.05), (ii) more significant increment of systolic systemic arterial pressure (8.7 +/- 2.7% in group iNO + Mil vs. 5.2 +/- 3.1% in group iNO, P < 0.05), and (iii) more significant improvement of arterial oxygen saturation (9.3 +/- 3.2% in group iNO + Mil vs. 6.8 +/- 2.8% in group iNO, P < 0.01). Occurrence of iNO withdrawal failure during its weaning or rebound after its discontinuation was significantly lower in group iNO + Mil. The combined use of iNO and milrinone provided additive benefits as compared with exclusive use of iNO for patients with elevated PVR after Fontan procedure.
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A control strategy for rotary blood pumps meeting different user-selectable control objectives is proposed: maximum support with the highest feasible flow rate versus medium support with maximum ventricular washout and controlled opening of the aortic valve (AoV). A pulsatility index (PI) is calculated from the pressure difference, which is deduced from the axial thrust measured by the magnetic bearing of the pump. The gradient of PI with respect to pump speed (GPI) is estimated via online system identification. ⋯ For maximum support, a low PI was maintained without inducing ventricular collapse. For maximum washout, the pump worked at a high PI in the transition region between the opening and the permanently closed AoV. The cascaded control of GPI and PI is able to meet different control objectives and is worth testing in vitro and in vivo.
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We present a regimen for anticoagulation in the immediate postoperative period after left ventricular assist device (LVAD) implantation using low molecular weight heparin (LMWH) as an alternative to unfractionated heparin. Between May and September 2007, eight consecutive patients undergoing LVAD implantation for advanced heart failure received the LMWH nadroparin. Nadroparin was given twice daily to achieve anti-Factor Xa activity target peak levels of 0.4 +/- 0.1 U/mL. ⋯ In two patients, pump thrombosis was suspected. There were two ischemic and no hemorrhagic strokes. The use of LMWH may provide a new anticoagulation treatment option in the immediate postoperative period after LVAD implantation.
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During the use of pulsatile extracorporeal life support (pulsatile-ECLS), the patient's venous pressure near the inlet venous catheter tip must be monitored to maintain sufficient blood flow and to prevent vein collapse. However, direct measurement of the venous pressure and the estimate of suction using measured blood inflow and prepump pressure are not practical because of setup difficulties during emergency treatments and in cardiovascular operations. In this article, we describe a new method for estimating the venous pressure that can be implemented in the controller of the pulsatile-ECLS system, the T-PLS. ⋯ Previously measured values of the pulsatile-ECLS compliance and the hemodynamic resistance along the inflow path are used to evaluate venous pressure with estimated blood flow. Estimated prepump pressure, inflow, and venous pressure were compared to the measured data in a series of in vitro experiments. The estimated venous pressure was used to avoid vein collapse and to increase the reliability in animal experiments.