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Although de-airing procedures are commonly performed during cardiac surgery, use of these procedures is not necessarily based on evidence. Uncertainly remains around the size of bubbles that can be detected by echocardiography, whether embolized air or carbon dioxide can be absorbed, and the reasons for embolic events occurring despite extensive de-airing. Since air bubbles are invisible in the blood, we used simple experimental models employing water and 10% dextran solution to determine the correlation between actual bubble size and the depicted size on echocardiography, bubble size, and floatation velocity and the absorption of carbon dioxide under embolization and irrigation conditions. Bubbles depicted as larger than 1 mm were overestimated by echocardiography: the actual size was larger than 0.4 mm in diameter. While bubbles of 0.5 mm had a floatation velocity of 2 to 3 cm/s, the buoyancy of bubbles smaller than 0.3 mm was negligible. Thus, bubbles that are depicted as larger than 1 mm on echocardiography or that present with apparent buoyancy should be visible and need to be meticulously removed. However, echocardiography cannot distinguish bubbles of around 0.1 mm in diameter from those of capillary size (<10 μm). Thus, we advise continuous venting of dense bubbles until they become sparse. While carbon dioxide was rapidly absorbed when circulating, the absorption of embolized carbon dioxide was negligible. These results suggest that detected intracardiac air represents residual "air," with carbon dioxide already absorbed. Therefore, the use of conventional de-airing procedures needs reconsideration: air and buoyant bubbles should be removed from the heart before they are expelled into the aorta; this requires timely and precise assessment with transesophageal echocardiography and effective collaboration between surgeons, anesthesiologists, and perfusionists., (© 2021 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.)

Efficacy for alleviating signs/symptoms of malignant ascites of a renovated CART (cell-free and concentrated ascites reinfusion therapy) system, called KM-CART, was evaluated. A total of 4781 KM-CART procedures were performed in 2109 patients. All patients were accepted unless hemodynamically unstable or consciousness impaired. The ascites were processed and drip-infused into the patient. There were no major complications or deaths. The mean drainage volume was 6.2 L (maximum: 27.7 L), patient symptoms (numerical scale system) were significantly alleviated (45.1 ± 19.0 reduced to 21.2 ± 14.2, P < .001), and patient leg circumference significantly decreased (33.3 ± 4.4 cm reduced to 30.5 ± 4.4 cm, P < .001) without exacerbation of renal function. Collected cancer cells could be utilized for immune therapy. KM-CART is capable of improving the "quality of best supportive care" and can be beneficial in conjunction with medication for alleviating malignant pain., (© 2020 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.)

Background: Surgical ring annuloplasty is generally performed in patients with symptomatic atrial functional mitral regurgitation (MR) caused by long-standing atrial fibrillation (AF). However, its clinical results have not been well reported., Methods: Twenty consecutive patients with atrial functional MR (mean age of 68 ± 9 years) and a left ventricular (LV) ejection fraction (EF) greater than 50% underwent mitral annuloplasty. Concomitant procedures included tricuspid valve surgery in 16 patients, AF ablation in 13 patients, and coronary artery bypass grafting in 2 patients. We reviewed the clinical outcomes of those patients and investigated the specific preoperative echocardiographic findings related to MR recurrence., Results: At discharge, the mean left atrial (LA) volume index and mean tricuspid regurgitation peak gradient had significantly decreased from 94 ± 59 mL/m 2 to 58 ± 30 mL/m 2 and from 34 ± 11mm Hg to 23 ± 5mm Hg, respectively. During the follow-up period of 28 ± 17 months, the New York Heart Association functional class significantly improved from 2.3 ± 0.6 to 1.3 ± 0.6. Four patients developed recurrent MR, and of those, two required reoperation. Those with recurrent MR had a significantly larger preoperative LV dimension than those without recurrent MR. Preoperative three-dimensional transesophageal echocardiography was performed in 12 patients, revealing a greater degree of leaflet tethering in patients with recurrent MR than that in patients without recurrent MR., Conclusions: In patients with the combination of atrial functional MR, left ventricular dilatation and excessive leaflet tethering, mitral annuloplasty alone may not be sufficient to achieve long-term correction of MR., (© 2019 Wiley Periodicals, Inc.)

The operation of cardiopulmonary bypass procedure requires an advanced skill in both physiological and mechanical knowledge. We developed a virtual patient simulator system using a numerical cardiovascular regulation model to manage perfusion crisis. This article evaluates the ability of the new simulator to prevent perfusion crisis. It combined short-term baroreflex regulation of venous capacity, vascular resistance, heart rate, time-varying elastance of the heart, and plasma-refilling with a simple lumped parameter model of the cardiovascular system. The combination of parameters related to baroreflex regulation was calculated using clinical hemodynamic data. We examined the effect of differences in autonomous-nerve control parameter settings on changes in blood volume and hemodynamic parameters and determined the influence of the model on operation of the control arterial line flow and blood volume during the initiation and weaning from cardiopulmonary bypass. Typical blood pressure (BP) changes (hypertension, stable, and hypotension) were reproducible using a combination of four control parameters that can be estimated from changes in patient physiology, BP, and blood volume. This simulation model is a useful educational tool to learn the recognition and management skills of extracorporeal circulation. Identification method for control parameter can be applied for diagnosis of heart failure., (© 2012, Copyright the Authors. Artificial Organs © 2012, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.)

In order to develop a diaphragm-type ventricular assist device (VAD), we studied the flow field change following structural modifications. We devised a center flow-type pump by putting a small projection on the center of the housing and/or diaphragm to provide a center in the flow field, and examined the following four types of VADs: N type without a projection, D type with a projection on the diaphragm, H type with a projection on the housing, and DH type with projections on both the diaphragm and housing. Computational fluid dynamics (CFD) was used for flow simulation. Particle image velocimetry (PIV) was also used to verify the reliability of the CFD method and to determine how the flow field changes in the presence of a projection. The results of the PIV and CFD analyses were comparable. The placement of a projection on the housing was most effective in rectifying the flow field.

The protective effect of the low power helium-neon (He-Ne) laser against the damage of human erythrocytes in whole blood was examined in a perfusion model using an artificial heart-lung machine. Preserved human whole blood was diluted and perfused in 2 closed circuits with a double roller pump. The laser irradiated one of the circuits (laser group), and none the other (control group). In the laser group, erythrocyte deformability and erythrocyte adenosine triphosphate (ATP) levels were significantly higher, and free hemoglobin levels were significantly lower than those in the control group. Subsequent morphological findings by means of scanning electron microscope were consistent with these results. Low power He-Ne laser protected human erythrocytes in the preserved diluted whole blood from the damage caused by experimental artificial heart-lung machines. The clinical application of low power laser treatment for extracorporeal circulation is suggested.

Percutaneous cardiopulmonary support (PCPS) has come to be applied for cardiopulmonary resuscitation and in the management of severe respiratory failure as well as severe heart failure. We investigated cerebral tissue oxygen saturation during PCPS in a canine model of respiratory failure using near-infrared spectroscopy. Animals were mechanically ventilated with 10% oxygen to make a respiratory failure model. Perfusion with PCPS was performed via the left femoral artery and switched to that via the right axillary artery. Cerebral tissue oxygen saturation was 54.2 +/- 3.4% during PCPS via the femoral artery and was 82.3 +/- 4.6% during PCPS via the axillary artery (p = 0.001). Hepatic tissue oxygen saturation was not significantly different. LV dP/dt max increased significantly after switching to the axillary blood supply (p = 0.001). Conventional PCPS may not have the capability of supporting cerebral circulation under severe respiratory failure without organic heart disease.

We have made an eccentric roller type total artificial heart (ERTAH). The ERTAH is a positive-displacement device comparable to a DeBakey roller pump. Its left and right outputs are determined by the size of its blood chambers, and the ratio of its left and right output is almost constant. We focused on an interatrial shunt to achieve left-right balance. We have conducted numerical simulation, a mock test, and an acute animal experiment to analyze left-right heart balance during ERTAH operation. Numerical simulation was performed under conditions in which the flow of the left artificial heart was fixed at 6 L/min, the flow of the right artificial heart was varied from 4.8 to 6 L/min, and the interatrial resistance was also varied. The relationship between the interatrial shunt flow rate and the output of the left and right artificial hearts was balanced when the flow of the right artificial heart was at 5.45 L/min. In a mock test, 2 DeBakey roller pumps were connected to the left and right sides of a Donovan mock circulatory system, and an interatrial shunt was created between the inlet ports of the left and right roller pumps. The interatrial resistance of the mock system was varied from 7.7, to 4.3, and to 2.9 mm Hg x min/L when the inner diameter of the interatrial shunt was 6, 8, and 10 mm, respectively. As in the mock test, 2 roller pumps were used to bypass the right and left hearts of a goat weighing 60 kg. The flow rate of the left heart was almost constant (4.7 L/min). The flow of the right heart was approximately 4.1 L/min when the interatrial shunt flow rate was zero. A leading consideration was that the left to left shunt through the bronchial arteries in this goat was approximately 0.6 L/min. In developing the ERTAH, we considered that creating an interatrial shunt between the inlet ports of the ERTAH as well as making a difference between the chamber volumes might be effective in balancing the left-right sides of the artificial heart.

Circulatory support using both intraaortic balloon pumping (IABP) and percutaneous cardiopulmonary support (PCPS) can improve general hemodynamics; however, sometimes brain damage occurs caused by hypoperfusion. Such cerebral hypoperfusion is likely to be caused by PCPS when applying the conventional femoral cannulation. We have developed a new IABP catheter which incorporates a conduit for PCPS with an outlet at the catheter tip, the goal of which is the improvement of cerebral perfusion. The hemodynamic characteristics of this new IABP catheter were compared with those of the conventional combination of IABP and PCPS. Studies were performed by mock test using a pulsatile artificial heart. A polyvinyl chloride tube acted as the aorta with 2 branches at the proximal and distal portions representing the upper and lower portions of the body. The IABP balloon was positioned between the 2 branches, and changes in flow at the 2 branches were examined at varying PCPS flow rates. Flow in the proximal branch using the new device was greater than it was using the conventional PCPS device. We conclude that cerebral perfusion could be improved with the use of this new special IABP catheter.

We have developed a direct mechanical left ventricular assist device (DMLVAD) for severe left ventricular failure. The DMLVAD was attached to the left ventricle and compressed the heart by a pneumatic driving unit. In a mock circulation model with an extracted nonbeating heart, a cardiac output (CO) of 1.93 L/min was obtained at a driving pressure of 200 mm Hg. In a canine left ventricular failure model induced by injection of sodium hydroxide into the myocardium, the systolic arterial pressure, systolic left ventricular pressure, maximum LV dP/dt, peak flow, and CO increased by 21, 24, 58, 144, and 37%, respectively. The mean left atrial pressure also decreased by 15% when the DMLVAD was driven. These effects were most prominent when the mean left atrial pressure was over 15 mm Hg, and the driving pressure was over 100 mm Hg. Compression at late systole was more effective in obtaining greater CO. We suggest that the DMLVAD could be an optional circulatory assist device for patients with left ventricular failure awaiting heart transplantation.

A new intravascular pumping oxygenator (IVPO) was developed for intravascular gas exchange and circulatory assistance in critically ill patients with respiratory and circulatory failure. The IVPO utilizes new silicone hollow fibers (diameter, 1 mm; membrane width, 50 microns) and consists of two driving tubes for the oxygenation and pumping of circulating blood. The performance characteristics of the IVPO were studied using an experiment ex vivo model. With a mean hemoglobin concentration of 10.5 +/- 2.3 g/dl, total oxygen transfer was 5.6 +/- 1.5 ml/min at a blood flow of 200 ml/min and 6.3 +/- 2.2 ml/min at a blood flow of 250 ml/min. Total CO2 transfer was 3.8 +/- 1.4 ml/min at a blood flow of 200 ml/min and 4.2 +/- 1.6 ml/min at a blood flow of 250 ml/min. Blood flow increased to a maximum of 250 ml/min during IVPO pumping. This preliminary experiment demonstrated that the IVPO has the capacity to function both as circulatory assist pump and as an intravascular hollow fiber oxygenator.

The membrane oxygenator often develops impaired gas exchange after prolonged use because plasma proteins adhere to the membrane's surface and leak through its micropores. This study was performed to examine the efficacy of high-frequency jet ventilation (HFJV) in minimizing these problems in a "flat plate" type of membrane oxygenator. We first vibrated the membrane of the oxygenator by HFJV from 1 to 10 Hz to find the frequency most effective for optimal gas exchange in animals with partial extracorporeal circulation. These studies suggested that 6 Hz HFJV was preferable in our model. We subsequently performed in vivo extracorporeal oxygenation in dogs for 8 h using the membrane oxygenator with or without 6 Hz HFJV. Although the gas exchange capacity within the first 8 h was similar in the two groups, after 6 h a significant decrease in the red blood cell count and in the hematocrit was found in the group not receiving HFJV. Scanning electron microscopic examination of the membranes after 8 h of use disclosed that the membrane from the group receiving HFJV had less plasma protein and fibrin adhesion than that from the group not receiving HFJV. Moreover, it appears that with prolonged extracorporeal oxygenation, 6 Hz HFJV also protects against a decrease in the hematocrit of the passed blood and might lead to enhanced gas exchange. Our data suggest that good gas exchange can be maintained for periods even longer than 8 h if HFJV is used in conjunction with the membrane oxygenator.

Transesophageal two-dimensional echocardiography has been used for intraoperative monitoring of regional wall motion of the left ventricle. Regional wall motion abnormality is a sensitive indicator of myocardial ischemia and the use of two-dimensional transesophageal echocardiography may have a substantial advantage for early detection of myocardial infarction and thus for initiating timely and appropriate therapy in preventing postoperative myocardial ischemia. With an expected increase in the use of intraoperative transesophageal echocardiography for monitoring regional wall motion, we described the practical aspects of transesophageal echocardiography: (1) insertion technique of transesophageal echocardiographic probe; (2) the technique for obtaining an optimal short-axis view of the left ventricle; and (3) the method for evaluating regional wall-motion abnormality and myocardial ischemia. Regional wall motion abnormality is best monitored at the mid-papillary muscle level where all three coronary arteries meet. In obtaining this view, the transesophageal echocardiographic probe was found to be predominantly located in the stomach. Failure in obtaining short-axis view of the left ventricle at this level occurred in patients with left ventricular dilatation or obesity. Because of the anatomical reason, the echocardiographic transducer cannot reach a proper plane. In anesthetized patients, air can be pushed into the stomach during induction and may disturb the visualization. The pitfalls in examining regional wall motion abnormalities include: (1) shifting of the center of left ventricular contraction; (2) inadequate direction of the scanning plane; and (3) paradoxical septal movement. Three cases are presented to demonstrate the usefulness of transesophageal echocardiography in managing coronary artery surgical patients.

This study was undertaken to assess the suitability for intraoperative pulmonary vein flow measurements in 15 patients undergoing coronary artery bypass grafting. Using two-dimensional color Doppler transesophageal echocardiography, all four pulmonary veins--right upper and lower and left upper and lower pulmonary veins were easily visualized. Pulmonary vein flow was pulsatile. J wave occurred in the ventricular systole with relaxation of the left atrium and K wave in the ventricular diastole with relaxation of the left ventricle. There were differences in suitability for flow measurements among four pulmonary veins: (1) consistent visualization; (2) stable visualization throughout measurement; (3) minimal angle between ultrasonic beam and pulmonary vein course; and (4) minimal shift of sampling volume during measurement. The left pulmonary veins were suitable for flow velocity measurement by transesophageal echocardiography. The left lower pulmonary vein was stable for visualization once it was visualized although the angle was occasionally large. The left upper pulmonary vein was consistently visualized although the angle was occasionally large. On the other hand, the right pulmonary veins were unsuitable for flow measurement. Since sampling volume shifted in the direction of the long axis by the average of 5 to 6 mm during cardiac cycle, it should be positioned inside of the pulmonary vein at about 5 mm from the orifice of the left atrium.