Cardiac supporting device using artificial rubber muscle: preliminary study to active dynamic cardiomyoplasty.

Dynamic cardiomyoplasty is a surgical treatment that utilizes the patient's skeletal muscle to support circulation. To overcome the limitations of autologous skeletal muscles in dynamic cardiomyoplasty, we studied the use of a wrapped-type cardiac supporting device using pneumatic muscles. Four straight rubber muscles (Fluidic Muscle, FESTO, Esslingen, Germany) were used and connected to pressure sensors, solenoid valves, a controller and an air compressor. The driving force was compressed air. A proportional-integral-derivative system was employed to control the device movement. An overflow-type mock circulation system was used to analyze the power and the controllability of this new device. The device worked powerfully with pumped flow against afterload of 88 mmHg, and the beating rate and contraction/dilatation time were properly controlled using simple software. Maximum pressure inside the ventricle and maximum output were 187 mmHg and 546.5 ml/min, respectively, in the setting of 50 beats per minute, a contraction/dilatation ratio of 1:2, a preload of 18 mmHg, and an afterload of 88 mmHg. By changing proportional gain, contraction speed could be modulated. This study showed the efficacy and feasibility of a pneumatic muscle for use in a cardiac supporting device.

Static cardiomyoplasty with synthetic elastic net suppresses ventricular dilatation and dysfunction after myocardial infarction in the rat: a chronic study.

Although static cardiomyoplasty prevents the left ventricle (LV) from dilatation, it may interfere with diastolic relaxation, or cause restriction. We developed a synthetic net with dual elasticity and tested its effect late after myocardial infarction in the rat. LV pressure-volume relationships (PVR) were successively analyzed before, after intravenous volume load, and 10 minutes after occlusion of the left anterior descending artery. Rats were then randomized into groups receiving synthetic net wrapping around the heart (NET+, n = 8) and only partially behind LV (NET-, n = 9), and they underwent the same PVR studies 6 weeks later. End-diastolic and end-systolic PVR were defined, and LV size and function were compared under standardized loading conditions. Although there was no difference in Day 0, increase in LV end-diastolic and end-systolic volumes were significantly attenuated in NET+ rats 6 weeks later when there was a significant correlation between LV volumes by PVR estimation and actual measurements, with significant differences in both measures between the groups: NET+ < NET-. The presence or absence of net did not show restrictive hemodynamics under acute volume load. Static cardiomyoplasty using a synthetic elastic net significantly attenuated LV dilatation and dysfunction without restriction late after myocardial infarction in the rat.

Tissue-engineered cardiac constructs for cardiac repair.

Several recent basic research studies have described surgical methods for cardiac repair using tissue cardiomyoplasty. This review summarizes recent advances in cardiac repair using bioengineered tissue from the viewpoint of the cardiac surgeon. We conclude that the results of many basic and preclinical studies indicate that bioengineered tissue can be adapted to conventional surgical techniques. However, no clinical studies have yet proved bioengineered tissue is effective as a treatment for human heart failure. Today's cardiac surgeons can look forward to the advent of new techniques to benefit patients who respond poorly to existing treatment for heart failure.

A novel catheter system for percutaneous intracoronary artery cardiomyoplasty.

BACKGROUND: Current medical and invasive treatment strategies are often found to be inadequate to treat patients with acute myocardial infarction. Cell and tissue therapies are a promising treatment alternative for patients with severe ischemic heart disease. OBJECTIVES: The objective of this study was to evaluate the efficacy of a new means of direct myocardial access using the percutaneous coronary intervention (PCI) technique. METHODS: We used a system consisting of an injection needle catheter that implants cells and the injection guide catheter that delivers the injection needle catheter into the target lesion. We harvested skeletal myoblasts from Yorkshire swine (n = 8; 50-60 kg), expanded them in culture and labeled them with a fluorescent cell-linker kit. The myoblasts (106 cells), along with green dye, were injected into the normal heart of swine using this novel system. Histological analysis was performed on Days 0 (n = 4) and 14 (n = 4) after injection. RESULTS: Working along the coronary artery, the catheter was easily delivered to the left anterior descending (LAD) coronary artery with the conventional PCI technique. No events of death, cardiac tamponade or other procedural complication occurred. Electrocardiography did not detect cardiac arrhythmia during the 14 days following the injection. On gross inspection, the heart was observed through its outer surface, and the myoblasts and green dye were well localized in the LAD area. CONCLUSIONS: The present study demonstrates the feasibility of a new means of a direct myocardial injection system without any adverse outcomes.

Cellular cardiomyoplasty: routes of cell delivery and retention.

Experimental and clinical studies have proven the feasibility of cellular cardiomyoplasty in treating the damaged myocardium following ischemic injury. Over the years, this field has exploded with different investigators trying different routes of cell delivery ranging from direct cell injection into the heart to peripheral intravenous delivery utilizing the various signaling mechanisms known. These different routes have resulted in a wide range of retention and engraftment of cells in the target tissues. In this review, we will explore the different modalities of cell delivery, the pros and cons of each route and the cellular retention and therapeutic efficacy of these routes. We will then look into the different theories that try to explain the observed retention and engraftment of cells in the target tissues. Finally, we will discuss various methods that can improve cellular retention and engraftment and hence better improvement in myocardial function.

[A pump to assist the cardiac insufficiency]. / Pompa do wspomagania niewydolnego serca.

The design of biopumps for long-run aiding of blood circulation remains an open issue. The cardio-surgical treatment used in clinical practice, i.e.the dynamic cardiomyoplasty, is a very vast operation, and although its obvious benefit is effective utilization of autogenous skeletal muscle craft, the final effect is of a passive adjunctive character. The models of biopumps fed by the skeletal muscle, operating against the principle of pressure exerted on the ventricle of the heart, have not found widespread clinical use because of problems of both design and surgical nature. A model of the pump presented in this article uses the skeletal muscle torsion force induced by electric impulses. The designed model of the pump offers a linear characteristic of the ejected volume in function with the tension rod elongation. The values of the maximum elongation of the tension rod and of the operating force are 4 cm and 5 kg, respectively, and as such are comparable with the mechanical parameters of the muscle operation. The frequency of pump operation under the conditions of full ejection and filling depends on the value and run of the force acting on the tension rod, on the pump output charge resistance, and on the pump filling run-off efficiency. For standard values of these parameters, the system is capable of operating at a frequency of 60 BPM. Results of the experiments with the skeletal muscle indicate that it satisfies the above requirements necessary for operating the biopump model.

Socks for the dilated heart. Does passive cardiomyoplasty have a role in long-term care for heart failure patients?

Dynamic cardiomyoplasty has been performed in over 1000 patients worldwide but due to limited success the procedure was never been adopted as an alternative approach for the surgical therapy of heart failure. However, observations in these patients showed that the nonstimulated or fibrotic transformed latissimus dorsi by itself led to an improvement of heart failure symptoms. These findings stimulated animal experiments with so-called passive cardiomyoplasty devices. In several animal models, the progression of heart failure could be stopped, and even reversed remodeling could be demonstrated. Several different devices have been developed and tested in animal models. The Acorn CorCap has already passed a successful clinical feasibility study. However, the final evaluation of two multicenter trials has to be awaited to assess the future role of this device in the treatment of heart failure.

Cardiomyoplasty: first clinical case with new cardiomyostimulator.

Dynamic cardiomyoplasty was performed in a patient using a new cardio-myostimulator (LD-PACE II) designed to enable a novel stimulation regimen that utilizes a new range of stimulation options, including cessation during sleep. After treatment, left ventricular ejection fraction improved in 24 months from 15% to 25% and New York Heart Association classification improved from class IV to II.

New advances in dynamic cardiomyoplasty: Doppler flow wire shows improved cardiac assistance in demand protocol.

No data have been published on real cardiac assistance with demand dynamic cardiomyoplasty. We tested the utility of a Doppler flow wire in measuring beat by beat aortic flow velocity and evaluating cardiac assistance in demand cardiomyoplasty patients. The technique was tested in seven patients (M/W = 6/1; age, 57.1+/-6.2 years; atrial fibrillation/ sinus rhythm = 1/6; New York Heart Association [NYHA] classification = 1.4+/-0.5). Measurements were done using a 0.018 inch peripheral Doppler flow wire advanced through a 5 French arterial femoral sheath. Three 1 minute periods with the stimulator off, and three 1 minute periods with clinical stimulation were recorded. We measured peak aortic flow velocity in all beats. Latissimus dorsi mechanogram was simultaneously recorded. Comparison between preoperative and follow-up data showed significantly higher values of tetanic fusion frequency and ejection fraction at follow-up, whereas mean NYHA class was significantly lower. Statistical analysis showed an increase in aortic flow velocity not only in the assisted versus rest period, but also in assisted versus unassisted beats (8.42+/-6.98% and 7.55+/-3.07%). A linear correlation was found between increase in flow velocity and latissimus dorsi wrap tetanic fusion frequency (r2 = 0.53). In demand dynamic cardiomyoplasty, systolic assistance is significant and correlated to the latissimus dorsi speed of contraction; a demand stimulation protocol maintains muscle properties and increases muscle performance.

LD Pace II, an easily programmable device for cardiomyoplasty.

The efficacy of programmable devices depends heavily on being able to select parameter values matched to the individual patient's needs. In many cases, physicians fail to make use of all of the features of a device because of programming complexities. This paper presents a new cardiomyostimulator, "LD Pace II", emphasising in particular its novel features and the steps taken to make the behaviour of the device easy for the physician to program.

LD-PACE II: a new cardiomyostimulator for cardiac bioassist.

The LD-PACE II was designed for use in cardiomyoplasty, aortomyoplasty, and skeletal muscle ventricles. All parameters specified as programmable can be changed in a noninvasive manner (using a programming interface wand connected to a computer using the Windows 95/98 environment). Two new functions may be very useful clinically, based on experimental research. 1. Work-rest regimen. The LD-PACE II is able to deliver alternating periods of muscle contractions and rest. Work and rest periods may be programmed independently between 1 and 120 minutes in increments of 1 minute. The work-rest regimen may be useful clinically if muscle contractions are needed for cardiac assist postoperatively. 2. Night/day regimen. This feature allows for a change in the ratio of muscle contractions according to a patient's activity level. During the day the cardiosynchronization ratio may be set from 1:1 to 1:4, and during the night it may be set for 1:8 to 1:16. This allows the muscle to have a long rest period, prevents overuse, and prolongs battery life. These two new features make this cardiomyostimulator very attractive for cardiomyoplasty in particular. The addition of the work-rest and night-day regimens allow the muscle to rest for periods during the day to prevent overuse, subsequent damage, and potential atrophy.

Study of muscular and ventricular function in dynamic cardiomyoplasty: a ten-year follow-up.

BACKGROUND: The basic physiologic principle underlying cardiomyoplasty is long-term electrostimulation of a latissimus dorsi muscle (LDM) wrapped around the heart to obtain a phasic activity that could be integrated with ventricular kinetics. The aim of cardiomyoplasty is to prolong survival and to improve the quality of life of patients with severe chronic and irreversible myocardial failure by improving systolic contraction and correcting diastolic dysfunction. METHODS: To evaluate the long-term outcome of cardiomyoplasty, we investigated 82 patients electively undergoing this procedure in-our hospital. All patients had severe chronic heart failure that did not respond to optimal medical treatment. Patients had a mean age of 50 +/- 12 years (84% males). The cause of heart failure was ischemic (55%), idiopathic cardiomyopathy (34%), ventricular tumor (6%), and other (5%). The mean follow-up was 4.3 years. RESULTS: The mean New York Heart Association functional class improved after operation from 3.2 to 1.8. Average radioisotopic left ventricular ejection fraction increased from 17% +/- 6% to 28% +/- 3% (p < 0.05). Stroke volume index increased from 35 +/- 9 to 46 +/- 8 ml/beat/m2 (p < 0.05). The heart size remained stable at long term (evaluated by echo and computed tomography scanning). After cardiomyoplasty the number of successive hospitalizations resulting from congestive heart failure was reduced to 0.4 hospitalizations/patient/year (before operation 2.5, p < 0.05). Computed tomography scans showed at long-term a preserved LDM structure in 82% of patients who underwent operation. Survival probability at 7 years was 54% for the totality of patients, and 66% for patients who underwent operation in New York Heart Association functional class 3. Five patients underwent heart transplantation after cardiomyoplasty (mean delay 29 months), principally as a result of the natural evolution of their underlying heart disease, without major technical difficulties. CONCLUSIONS: Our 10-year clinical experience demonstrates that cardiomyoplasty increases ejection fraction, improves functional class, and ameliorates quality of life. Ventricular volumes and diameters remain stable long term. LDM structure is maintained long term if electrostimulation is performed avoiding excessive myostimulation. Patient selection is the most important determinant for early and late outcome. Late death in patients undergoing cardiomyoplasty is principally due to sudden death. Our future aim is to incorporate a cardioverter-defibrillator in the cardiomyostimulator, thus improving long-term results. Cardiomyoplasty may delay or prevent end-stage heart failure and the need for heart transplantation.

[Surgical alternatives to direct repeat revascularization of coronary arteries--common mechanisms for reducing ventricular volume, laser transmyocardial revascularization and cardiomyoplasty]. / Alternatives chirurgicales á la revascularisation directe itérative des artéres coronaires--mécanismes communs de la réduction du volume ventriculaire, de la revascularisation transmyocardique au laser et de la cardiomyoplastie.

There are a number of surgical alternatives to repeat artery bypass grafting, which is the primary treatment for recurrent severe myocardial ischemia. In patients with endstage coronary artery disease unsuitable for repeat bypass procedures, orthotopic heart transplantation is now well established. However, the increasing donor shortage limits this option to relatively few patients, a fact well documented by longer waiting lists despite less stringent donor criteria. Hence, other surgical therapies, which may at this time be underused, should be explored. In addition to mechanical circulatory support by means of implantable blood pumps which are now available with wearable drivers and rechargeable batteries, mention should be made of surgical left ventricular volume reduction and reverse remodeling, transmyocardial laser revascularization (TMR), and dynamic cardiomyoplasty. The mechanisms that explain the beneficial effects of the three latter procedures are not fully understood. But it may be speculated for these procedures that Laplace and Starling laws play a major role in the sometimes spectacular recovery. It is probably due to the complexity of the procedures mentioned, the severe condition of the patients, the high risk of a proactive attitude under such circumstances, and the significant cost, that the number of these alternative procedures performed is still rather low despite the fact that the results are similar to those of transplantation. However, careful individual evaluation is of prime importance for better results. The presence or absence of symptoms is certainly a major issue for the decision-making process. If the left ventricular ejection fraction is preserved, transmyocardial laser revascularisation may relieve angina. Dynamic cardiomyoplasty may be appropriate if the left ventricular ejection fraction is low, provided the heart is not too big and that there is neither too much mitral regurgitation nor major arrhythmia. If the left ventricle is very big and major mitral regurgitation is present, volume reduction giving transventricular access to the mitral valve can be evaluated. A decision-making tree is proposed.

[Dynamic cardiomyoplasty]. / Dynamische Kardiomyoplastik.

Between 1965 and 1995 the incidence of heart failure has been constantly rising and the mortality from this disease has increased fivefold. The introduction of ACE-inhibitors and of adrenergic beta-blockers have resulted in major symptomatic improvements in patients with mild to moderate heart failure. For end-stage disease, heart transplantation offers by now the only therapeutic option and yields excellent results. The permanent implantation of left heart assist-devices is just gaining increasing importance. Yet, both methods also have inherent drawbacks and may not be available to all patients, so that new methods are constantly evaluated. Cardiomyoplasty was introduced into clinical practice in 1985 by Alain Carpentier and since then more than 700 patients have been operated worldwide. After dissection of the latissimus dorsi muscle it is wrapped around the heart in a clockwise fashion (Figure 1). Two sensing electrodes are placed on the anterior aspect of the right ventricle and two stimulation electrodes between the proximal branches of the thoracodorsal nerve (Medtronic SP 5548). The electrodes are then connected with a burststimulator (Cardiomyostimulator, Medtronic 4710) (Figure 2). During the first 2 weeks following the operation the muscle is not stimulated in order to allow for the healing process. Thereafter, a stimulation protocol with a programmed, staged increase of the stimulation frequency is started, to induce transformation of the skeletal muscle into a "fatigue resistant" tissue. After 3 months the muscle is stimulated with every second heart beat (2:1 mode) with full burstimpulses containing 6 single impulses per burst for a duration of 185 ms (Figure 3). Cardiomyoplasty was conceived for patients in NYHA III and severely impaired myocardial function, in whom drug treatment does not produce the expected benefits. The criteria for patient selection are strictly followed, since it has been shown in the past, that the preoperative condition of the patient is of specific importance for the postoperative outcome. Contraindications are NYHA IV, advanced right ventricular dysfunction, secondary pulmonary hypertension (> 600 dyn x s x cm-5), LV end-diastolic diameter > 70 mm und AV-valve incompetence > Grad II. Between July 1985 und October 1996 647 patients received a cardiomyoplasty with the Medtronic Cardiomyoplasty System and the results from 438 patients were analyzed from the "Worldwide Cardiomyoplasty Study Group". One and 2 years following the operation NYHA-class had improved by one class in 41.9% and 53.3%, respectively, and by 2 classes in 38.1% and 30.5%, respectively. In 16% and 15% no improvement was found (Figure 4). Prospective investigation of the quality of life by a score revealed a considerable improvement in the level of daily activities and social interaction. In contrast, two years after the operation, only a small, but significant increase in LV-EF from 22.9 +/- 8.1% to 25.8 +/- 9.7% (p < 0.05) was shown. Heart rate, maximal O2-consumption, total exercise time, cardiac index, stroke volume and stroke work index did not change. According to the results of a recent FDA-study, in-hospital mortality was 12% between 1991 and 1993, and was reduced during a second phase starting 1994 to < 3%. One, 2 and 3-year survival of 349 patients who were in NYHA-III prior to the operation was 69%, 56% und 47%, respectively. 43 patients who were operated in NYHA IV exhibited considerably worse survival with only 48% after 1 year and 30% after 2 years, respectively. In a subgroup of 103 patients with a statistically low operative risk, 1, 2 and 3-year survival was 77%, 71% und 61%, respectively (Figure 5). As a mechanism of action the skeletal muscle wrap exerts some active improvement of systolic wall motion of the heart/skeletal muscle complex. However, probably more important is an acute and chronically persisting shift of the pressure-volume relation to the left. This process results in a "reverse remodel

Examination of epimysial leads used to stimulate the latissimus dorsi muscle.

Cardiomyoplasty is a new surgical treatment for heart failure in which the patient's latissimus dorsi muscle (LDM) is isolated, wrapped around the heart, and electrically stimulated to provide cardiac assistance. At present, long term stimulation of the LDM is achieved with intramuscular electrodes, which produce minimal nerve damage. This study examined the use of epimysial electrodes by measuring the epimysial lead characteristics during a four-week LDM training. Lead resistance started at 463 +/- 41 omega after implantation, decreased during the following week (251 +/- 16 omega), and remained less than the initial value during the last three weeks (weeks two: 282 +/- 19 omega and week four: 341 +/- 28 omega). The recruitment properties were similar to nervecuff electrodes: low threshold voltages (week one: 0.75 +/- 0.12, week two: 0.90 +/- 0.33, week four: 0.52 +/- 0.10 V) and a very steep recruitment curve with low saturation voltages. Histological examination revealed normal muscle fibers with no inflammatory response. Epimysial leads may be more convenient for most surgeons because the design does not require any free-dissection of the nerve nor guiding a needle around the nerve with the risk of perforating vessels or nerve branches. These results indicate that epimysial leads are worthy of further investigation.

Dynamic myoplasty: surgical transfer and stimulation of skeletal muscle for functional substitution or enhancement.

Dynamic myoplasty combines muscle transfer with electrical stimulation to provide contractile function that augments or replaces impaired organ function. Dynamic cardiomyoplasty was the first clinical application in which a skeletal muscle, latissimus dorsi, was transferred and stimulated to provide cardiac assistance, a function different from its original one. The problem of early muscle fatigue that was encountered in the initial implementation of the method was solved by training the muscle with electrical stimulation and thus changing its fiber composition. With intramuscular electrodes, the conditioned latissimus dorsi is stimulated in synchrony with the heart muscle. Safeguards are built into the two-channel implanted stimulator to avoid excessively high pulse rates. Clinicians report that 80% of patients with moderate to severe heart failure prior to operation showed a clinical improvement of 1.6 New York Heart Association classes. Alternative methods of providing cardiac assistance that are also being investigated include wrapping the muscle around the aorta, creating a skeletal muscle ventricle, and using the muscle to power an implantable pump. These latter techniques are still under preclinical investigation. Compared with heart transplant, cardiomyoplasty has the great advantage of not being subject to tissue rejection. The second principal application of dynamic myoplasty is treatment of fecal incontinence through creation of an electrically stimulated skeletal muscle neosphincter (ESMNS). The gracilis muscle of the leg is mobilized, wrapped around the anal canal, and conditioned with electrical stimulation to become more fatigue resistant. To achieve continence, the muscle is continuously stimulated except when the patient wishes to defecate. Overall success rates in achieving continence are 60-65%. Both cardiomyoplasty and the ESMNS technique, and their associated devices, are being refined through ongoing clinical trials.

[Circulatory support by an electrically stimulated muscle flap. Experimental experiences]. / Kreislaufunterstützung durch elektrisch stimulierte Muskellappen. Experimentelle Erfahrungen.

Functional electrical stimulation of the latissimus dorsi muscle flap for circulatory assistance extends the traditional concept of using this flap for reconstructive procedures into the field of cardiac surgery. It requires a transformed muscle which is able to contract for long periods of time without fatigue. Two main groups of experiments have been carried out in sheep. In six sheep the latissimus dorsi muscle (MLD) was transformed into a fatigue-resistant muscle by the means of multichannel stimulation of the supplying motor nerve. After that, stimulation of MLD at a frequency of 70 contractions per minute could be performed continuously without significant muscle fatigue. The loss of maximal force caused by the conditioning procedure was about one third of the initial force. In a second series of acute experiments the MLD was used for cardiomyoplasty. The muscle was divided into two parts which were wrapped around the heart in two different forms. The resting tension of the muscle was preserved. EKG-synchronous stimulation resulted in an increase in left ventricular pressure between 12 and 53%. The increase in arterial pressure was between 10,6 and 58%.

[Mechanical system of left ventricle cannulation: control of tightness by experimental left ventricular assistance]. / Système mécanique de canulation ventriculaire apicale: contrôle de l'étanchéité par assistance ventriculaire gauche expérimentale.

We have designed a mechanical device for left ventricular apex cannulation (SCAV). It will be used to implant a ventricular connection for a skeletal muscle ventricle placed in apicoaortic configuration without cardio-pulmonary bypass. The aim of this study was to assess the tightness of the ventricular connection at 48 hours. We used a left ventricular assist device (Biomedicus centrifugal pump) placed between the apex of the left ventricle and the descending thoracic aorta on 10 female sheep. The ventricular connection between the apex of the left ventricle and the Biomedicus was carried out with the SCAV and without cardio-pulmonary bypass. The intra-operative mortality was 10% (1 sheep) due to ventricular fibrillation. Three sheep died early in the run of the ventricular assistance due to technical assistance problems not related to the SCAV. The full ventricular assistance could be managed in 6 sheep through 32 h 30 (range from 15 to 46 h). No death occurred in these 9 sheep due to cardiac hemorrage or tamponade. The average apical bleeding in the pericardial drain was 157 ml (range from 20 to 270 ml). The tightness of the ventricular connection was proved by this study. The SCAV may be suitable for apical implantation of a skeletal muscle ventricle in sheep.

[Biomechanical heart and cardiovascular support]. / Biomechanische Herz- und Kreislaufunterstützung.

A surgical association between skeletal muscle and heart muscle dates back to experiments at the beginning of this century. Initially, the use of skeletal muscles aimed at plastic reconstructions of myocardial defects and enhancement of myocardial blood flow. The application of the contractile force of the skeletal muscle failed because of skeletal muscle fatigue. In the late sixties, investigations in muscle physiology demonstrated the "functional plasticity" of muscle tissue: Chronic electrical stimulation induces a transformational process of the cellular organelles, the metabolism, the fiber proteins and the calcium regulatory systems which results in "fatigue resistance" of the muscle. This was is a prerequisite for the application of skeletal muscles for continuous support of the circulation. Biomechanical support of the heart and the circulation is experimentally performed as skeletal muscle ventricles, chronic extraaortic counterpulsation and ventricular and atrial cardiomyoplasty. The electrical stimulation is performed with "burst" impulses, in order to increase the force and the length of contraction. The first clinical application of ventricular cardiomyoplasty is attributed to the French surgeon Alain Carpentier. Clinical investigations show that cardiomyoplasty results in an impressive symptomatic improvement of the patients clinical condition with only moderate changes of objective hemodynamic parameters. Further research will investigate the clinical applicability of the other, thus far only experimental techniques of biomechanical support. The introduction of cardiomyoplasty has induced great scientific interest in all forms of skeletal muscle circulatory support. Close collaboration between basic researchers and clinical investigators is of utmost importance for further developments in this field. The combined international research effort can be expected to yield considerable progress within the forthcoming years.