hronic congestive heart failure (CHF) is a complex metabolic syndrome resulting from global hypoperfusion and neurohumoral activation. Sympathoadrenergic hyperactivity and stimulation of the reninangiotensin -aldosterone cascade promote endothelial dysfunction in the macro-and microcirculation, and thus influence the distribution of the terminal blood flow. The increased total peripheral resistance, reduction of blood supply and impaired peripheral vascular dilatation in response to vasodilator stimuli result in atrophy of skeletal muscle and decreased oxidative activity. Physical training could reverse the pathologic changes in patients with CHF and there have been many reports during the past decade that clearly demonstrate the benefits of exercise on functional capacity, ventilation, metabolic status, autonomic control of heart rate (HR) variability and other parameCirculation Journal Vol. 70, January 2006 ters, 1-5 including skeletal muscle performance and impaired endothelial function. 6,7 However, most of the actual training protocols are based on systemic exercise requiring increased cardiac output, which cannot be achieved by all patients, and in general are only suitable for patients with a moderately advanced grade of CHF; less attention has been paid to the development of safe and efficient training programs for patients with severe grades of the disease. Background This study was designed to evaluate the effects of low-frequency electrical stimulation (LFES) on muscle strength and blood flow in patients with advanced chronic heart failure (CHF). Methods and ResultsPatients with CHF (n=15; age 56.5±5.2 years; New York Heart Association III -IV; ejection fraction 18.7±3.3%) were examined before and after 6 weeks of LFES (10 Hz) of the quadriceps and calf muscles of both legs (1 h/day, 7 days/week). Dynamometry was performed weekly to determine maximal muscle strength (Fmax; N) and isokinetic peak torque (PTmax; Nm); blood flow velocity (BFV) was measured at baseline and after 6 weeks of LFES using pulsed-wave Doppler velocimetry of the right femoral artery.

To obtain a physiological response by a total artificial heart (TAH), while eliminating the hemodynamic abnormalities commonly observed with its use, we proposed the use of a conductance- and arterial pressure-based method (1/R control) to determine TAH cardiac output. In this study, we endeavored to make use of a variable more closely tied to central nervous system (CNS) efferents, systemic conductance, to provide the CNS with more direct control over the output of the TAH. The control equation that calculates the target cardiac output of the TAH was constructed on the basis of measurement of blood pressures and TAH flow. The 1/R control method was tested in TAH-recipient goats with an automatic method by using a microcomputer. In 1/R control animals, the typical TAH pathologies, such as mild arterial hypertension and substantial systemic venous hypertension, did not occur. Cardiac output varied according to daily activity level and exercise in a manner similar to that observed in natural heart goats. These results indicate that we have determined a control method for the TAH that avoids hemodynamic abnormalities exhibited by other TAH control systems and that exhibits physiological responses to exercise and daily activities under the conditions tested. The stability of the control and the complete lack of inappropriate excursions in cardiac output is suggestive of CNS involvement in stabilizing the system.

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SUMMARYThe aim of this study was to investigate whether electrical stimulation of skeletal muscles could represent a rehabilitation alternative for patients with chronic heart failure (CHF). Thirty patients with CHF and NYHA class II-III were randomly assigned to a rehabilitation program using either electrical stimulation of skeletal muscles or bicycle training. Patients in the first group (n = 15) had 8 weeks of home-based low-frequency electrical stimulation (LFES) applied simultaneously to the quadriceps and calf muscles of both legs (1 h/day for 7 days/week); patients in the second group (n = 15) underwent 8 weeks of 40 minute aerobic exercise (3 times a week). After the 8-week period significant increases in several functional parameters were observed in both groups: maximal VO 2 uptake (LFES group: from 17.5 ± 4.4 mL/kg/min to 18.3 ± 4.2 mL/kg/min, P < 0.05; bicycle group: from 18.1 ± 3.9 mL/kg/min to 19.3 ± 4.1 mL/kg/min, P < 0.01), maximal workload (LFES group: from 84.3 ± 15.2 W to 95.9 ± 9.8 W, P < 0.05; bicycle group: from 91.2 ± 13.4 W to 112.9 ± 10.8 W, P < 0.01), distance walked in 6 minutes (LFES group: from 398 ± 105 m to 435 ± 112 m, P < 0.05; bicycle group: from 425 ± 118 m to 483 ± 120 m, P < 0.03), and exercise duration (LFES group: from 488 ± 45 seconds to 568 ± 120 seconds, P < 0.05; bicycle group: from 510 ± 90 seconds to 611 ± 112 seconds, P < 0.03). These results demonstrate that an improvement of exercise capacities can be achieved either by classical exercise training or by home-based electrical stimulation. LFES should be considered as a valuable alternative to classical exercise training in patients with CHF. (Int Heart J 2006; 47: 441-453)

This study has three purposes, as follows. The first is to develop a microscopic system to observe the microcirculation of animals implanted with an artificial heart. The second is to investigate the influence of flow pattern change from pulsatile to nonpulsatile on the microcirculation. The third is to study the effects of pulsatility in blood flow on endothelium-derived nitric oxide release in the microvasculature. When the flow pattern was changed from pulsatile to nonpulsatile, the velocity of erythrocytes in many capillaries dropped and remained at a low level, and the number of perfused capillaries decreased. After the flow pattern was returned to pulsatile, the velocity of erythrocytes recovered to the initial level. In many cases, the flow of nonperfused capillaries recovered to the initial level as well. Also, the pulsatile flow enhances the basal and flow-stimulated endothelium-derived nitric oxide release in microvessels.

The helical flow pump (HFP) is a novel rotary blood pump invented for developing a total artificial heart (TAH). The HFP with a hydrodynamic levitation impeller, which consists of a multi-vane impeller involving rotor magnets, stator coils at the core position, and double helical-volute pump housing, was developed. Between the stator and impeller, a hydrodynamic bearing is formed. Since the helical volutes are formed at both sides of the impeller, blood flows with a helical flow pattern inside the pump. The developed HFP showed maximum output of 19 l/min against 100 mmHg of pressure head and 11 % maximum efficiency. The profile of the H-Q (pressure head vs. flow) curve was similar to that of the undulation pump. Hydrodynamic levitation of the impeller was possible with higher than 1,000 rpm rotation speed. The normalized index of the hemolysis ratio of the HFP to centrifugal pump (BPX-80) was from 2.61 to 8.07 depending on the design of the bearing. The HFP was implanted in two goats with a left ventricular bypass method. After surgery, hemolysis occurred in both goats. The hemolysis ceased on postoperative days 14 and 9, respectively. In the first experiment, no thrombus was found in the pump after 203 days of pumping. In the second experiment, a white thrombus was found in the pump after 23 days of pumping. While further research and development are necessary, we are expecting to develop an excellent TAH with the HFP.

A new system toI observe the microcirculation on the bulbar conjunctiva was developed using a digital high definition microscope to investigate the influence of the flow patterns on the microcirculation in a goat with a total artificial heart (TAH). The undulation pump TAH was implanted into the goat. When the whole body condition became stable, the flow pattern was modulated between the pulsatile and the nonpulsatile mode, and the changes in the microcirculation were observed. When the flow pattern was changed from pulsatile to nonpulsatile mode, the erythrocyte velocity in capillaries dropped from 526 Ϯ 83 to 132 Ϯ 41 m/s and remained at a low level. The number of perfused capillaries decreased as well. Then the nonpulsatile flow mode was maintained for 20 minutes. After the flow pattern was returned to the pulsatile mode again, the erythrocyte velocity recovered to the initial level (433 Ϯ 71 m/s). In many cases, the flow of the nonperfused capillaries in the nonpulsatile mode recovered to the initial level after the flow pattern was changed to the pulsatile mode again. The perfused capillary density in the nonpulsatile mode (19.7 Ϯ 4.1 number of capillaries/mm) was significantly lower than that in the pulsatile mode (34.7 Ϯ 6.3 number of capillaries/mm).It is thought that the basal and flow stimulated endothelium derived nitric oxide release in the microvessels decreased because of the disappearance of pulsatility and that the nitric oxide induced the constriction of arterioles after the flow pattern was changed to the nonpulsatile mode. At the same time, the baroceptors might sense the decrease in the arterial peak pressure or dp/dt, and the sympathetic nerve increases activities and induce the constriction of arterioles. Then, the erythrocyte velocity in capillaries would decrease. Because of the flow pattern further in the chronic phase, it is important to follow the change in the microcirculation. ASAIO Journal 2004; 50:321-327. mplantation of the total artificial heart (TAH) triggers complex responses in the recipient's organism. Therefore, an important question is whether the microcirculation (MC) of the animal with a TAH is kept normal . The physiologic relations of the cardiovascular system can be changed and can lead to significant alterations because of a TAH. 1-2 Artificial perfusion is a complex process, and, at this point, the interactions taking place on the level of central and peripheral regulations are not fully understood. There is also another long standing question of whether arterial pulsation is essential to maintain adequate blood flow and aerobic metabolism in key organs. Nonpulsatile circulation has been widely used in the clinical setting of cardiopulmonary bypass or circulation support. 3-5 Many studies have been performed in cardiopulmonary bypass or in left ventricular support. 6 -13 In some studies, the organ to which attention was directed was the brain. 14 -20 The undulation pump total artificial heart (UPTAH) is an implantable TAH that has been in development at the Univers...

The undulation pump is a small size continuous flow displacement type blood pump that has been developed for an artificial heart. Using undulation pumps, 2 types of implantable total artificial hearts (TAHs), the undulation pump TAH (UPTAH) type 1 (UPTAH 1) and UPTAH type 2 (UPTAH 2) were developed. Both UPTAHs were designed to be small enough to implant into the chest of a goat, the experimental animal. UPTAH 1 could be reduced in size to 75 mm in diameter and 78 mm in length. The weight was 520 g. UPTAH 2 could be reduced in size to 75 mm in diameter and 80 mm in length. The weight was 650 g. UPTAH 2 could be tested in an animal experiment using an adult female goat weighing 52.3 kg. The UPTAH 2 could be implanted successfully into the goat's chest with a good fit. The goat stood after the surgery and extubation and survived for 3 h and 40 min; thus, the potential of the UPTAH for a practical implantable TAH was demonstrated.