Myocardial substitution with a stimulated skeletal muscle: first successful clinical case

Intervening to Preserve Function in Ischemic Cardiomyopathy with a Porous Hydrogel and Extracellular Matrix Composite in a Rat Myocardial Infarction Model

Multiple hydrogels are developed for injection therapy after myocardial infarction, with some incorporating substances promoting tissue regeneration and others emphasizing mechanical effects. In this study, porosity and extracellular matrix-derived digest (ECM) are incorporated, into a mechanically optimized, thermoresponsive, degradable hydrogel (poly(N-isopropylacrylamide-co-N-vinylpyrrolidone-co-MAPLA)) and evaluate whether this biomaterial injectate can abrogate adverse remodeling in rat ischemic cardiomyopathy. After myocardial infarction, rats are divided into four groups: NP (non-porous hydrogel) without either ECM or porosity, PM (porous hydrogel) from the same synthetic copolymer with mannitol beads as porogens, and PME with porosity and ECM digest added to the synthetic copolymer. PBS injection alone is a control group. Intramyocardial injections occurred 3 days after myocardial infarction followed by serial echocardiography and histological assessments 8 weeks after infarction. Echocardiographic function and neovascularization improved in the PME group compared to the other hydrogels and PBS injection. The PME group also demonstrated improved LV geometry and macrophage polarization (toward M2) compared to PBS, whereas differences are not observed in the NP or PM groups versus control. These results demonstrate further functional improvement may be achieved in hydrogel injection therapy for ischemic cardiomyopathy by incorporating porosity and ECM digest, representing combined mechanical and biological effects.

Ventricular stabilization with a customized decellularized cardiac ECM-based scaffold after myocardial infarction alters gene expression in a rodent LAD-ligation model

Objectives: Decellularized extracellular matrix (dECM) is increasingly used in a wide range of regenerative medicine applications and may also offer the potential to support injured myocardium. Here, we evaluated the myocardial gene expression pattern after myocardial infarction (MI) in a standardized rodent LAD-ligation model with and without ventricular stabilization with a customized, cardiac dECM-based scaffold (cdECM). Methods: MI was induced in male Wistar rats by standard LAD-ligation and confirmed 14 days post-intervention by echocardiographic parameters (FAS<40%). Cardiac ECM from donor rats was used to generate individual cdECM-scaffolds (tissue engineered myocardial sleeve, TEMS), which were epicardially implanted after confirmed MI for ventricular stabilization. After 4 and 8 weeks heart function was assessed by echocardiography, rats were sacrificed and explanted hearts were analyzed. In addition to histological analysis, standardized anterior left ventricular wall myocardial tissue samples were assessed by quantitative real-time PCR evaluating the specific gene expression pattern for immunomodulatory (IL-10, TGFBR2, TNFα), pro-angiogenic (VEGFA, FGF2, PGF, PDGFB), pro-survival (HGF, SDF1, IGF1, AKT1), remodeling-associated (TIMP1, MMP2, MMP9) and infarction-specific (NPPA, NPPB) markers. Results: Ventricular stabilization led to integration of the TEMS-scaffold into the myocardial scar with varying degrees of cellular infiltration, as well as significantly improved echocardiographic parameters demonstrating attenuation of maladaptive cardiac remodeling. Further, TEMS implantation after MI altered the myocardial gene expression pattern. Differences in gene expression were most striking after 4 weeks with significantly reduced expression of NPPA (0.36 ± 0.26 vs 0.75 ± 0.40; p < 0.05), NPPB (0.47 ± 0.25 vs 0.91 ± 0.429; p < 0.01), TGFBR2 (0.68 ± 0.16 vs 0.90 ± 0.14; p < 0.01) and PDGFB (0.81 ± 0.13 vs 1.06 ± 0.14; p < 0.01) as well as increased expression of IL-10 (5.93 ± 5.67 vs 1.38 ± 0.60; p < 0.05), PGF (1.48 ± 0.38 vs 1.09 ± 0.25; p < 0.05) and IGF1 (1.67 ± 0.70 vs 1.03 ± 0.42; p < 0.05). However, after 8 weeks differences in the gene expression patterns of remodeling-associated, and pro-angiogenic markers could still be observed between groups. Conclusion: Ventricular stabilization via TEMS implantation after MI did not only led to biological integration of the cdECM-scaffolds into the host tissue and improved functional cardiac parameters, but also altered 4 and 8 week gene expression of infarcted myocardium, possibly contributing to reducing chronic deteriorating effects while increasing the potential for myocardial regeneration.

Organ-saving surgical alternatives to treatment of heart failure

Over time, various surgical treatment strategies have evolved to manage advanced heart failure (HF). Scientific and technological breakthroughs through the last 50 years have put forward various surgical alternatives to patients with advanced HF encompassing surgical ventricular restoration to surgical gene therapy and stem cell replacement of the diseased ventricles. Organ-saving surgical options which used to be promising included dynamic cardiomyoplasty, partial resection of ventricle and cardiac wrapping with Acorn CorCap cardiac support device. These procedures were eventually abandoned due to negative outcomes and without proven disadvantages. Another organ-saving surgical option currently being considered but still make little sense is cardiac regeneration by stem cell therapy, i.e., cardiomyocyte restoration and replacement. Presently, the organ-saving surgical alternatives to treat end-stage HF are revascularization for ischemic cardiomyopathy, mitral valve surgery (repair or replacement) for ischemic mitral incompetence (IMI), left ventricular (LV) aneurysmectomy (surgical ventricular restoration) and mitral valve repair for IMI. These aforementioned procedures have become quite established approaches and with increasing experience are continuously being modified to improve outcome. Various mechanical circulatory support systems have emerged over time to improve functional status of patients with advanced HF, either as a bridge to heart transplantation or as a bridge to myocardial recovery. Likewise offered in those with contraindications to transplantation. Ventricular assist devices (VAD) can keep patients alive until an eventual transplantation. This article reviews the variety of the myriad of alternative organ-saving surgical alternatives that have been available or are currently available provided to patients with end-stage HF, their advantages and deficiencies, as well as prospects in HF therapy.

Left ventricular restoration devices post myocardial infarction

Even in the era of percutaneous reperfusion therapy, left ventricular (LV) remodeling after myocardial infarction (MI) leading to heart failure remains a major health concern. Contractile dysfunction of the infarcted myocardium results in an increased pressure load, leading to maladaptive reshaping of the LV. Several percutaneous transcatheter procedures have been developed to deliver devices that restore LV shape and function. The purposes of this review are to discuss the spectrum of transcatheter devices that are available or in development for attenuation of adverse LV remodeling and to critically examine the available evidence for improvement of functional status and cardiovascular outcomes.

2017Spring PaduaMuscleDays, roots and byproducts

The second 2017 issue of EJTM volume 27 contains the collection of abstracts from the 2017Spring PaduaMuscleDays conference, that was held March 23-25 in Montegrotto, Euganei Hills, Padova, Italy. In addition to a brief history of the Padova Myology Meetings held during the last 30 years, the present and the future of the PaduaMuscleDays conference are discussed with special reference to new media and the options they offer to spread to a larger audience the results of the many workshops held in the Hotel Augustus conference hall and in the Aula Guariento of the Accademia Galileiana di Scienze, Lettere ed Arti, one of the hidden treasures of the medioeval Padua, Italy. Preliminary announcements of the 2017 and 2018 events, in particular of the Giovanni Salviati Memorial, will follow.

INVESTIGATION OF SHAPE MEMORY ALLOY SPRING ELASTIC COEFFICIENT BASED ON VARYING APPLIED CURRENTS IN A CARDIAC ASSIST DEVICE

This paper analyses the mechanical properties of shape memory alloy (SMA) springs based on different electric currents applied in a cardiac assist device (CAD). Experimental results show that when the input drive current is constant, the SMA spring is equivalent to a tension spring with determined elastic coefficient that increases with the current. Based on our experiments, the theoretical maximum recovery force produced by SMA can be obtained through this input current. The phase transformation of SMA from austenite to martensite is able to be controlled by the drive current instead of the surface temperature of SMA. In addition, this experiment designed a cardiac supporting device composed of eight SMA springs, and used a saline bag to simulate human heart. The peak pressure inside the saline bag produced by this device was 17.4% of the normal heart systolic pressure. Our results can provide further support for the research of advanced CAD.

Right ventricular dynamic cardiomyoplasty for the univentricular heart with pulmonary hypertension

OBJECTIVES

We conducted an acute experimental study to test the feasibility of dynamic cardiomyoplasty in a setting of modified Fontan procedure for univentricular heart with pulmonary hypertension to obtain a possible proxy for high-risk Fontan candidates.

METHODS

After electrical preconditioning of the left latissimuss dorsi for 6 weeks in 8 dogs, the right ventricular cavity was totally obliterated with concomittent closure of the tricuspid valve and right pulmonary artery. Modified Fontan circulation was established with the aortic homograft anastomosed between the right atrium and pulmonary trunk, incorporated with a pericardial pouch as a compression chamber (neoright ventricle) fixed onto the epicardial surface of the ventricle. After cardiopulmonary bypass termination, a latissimus dorsi was applied to wrap the pericardial pouch and ventricle clockwise and stimulated with a trained-pulse (25 Hz) at 1:1 synchronization ratio with cardiac beats.

RESULTS

Profound right heart failure was noted during Fontan circulation in increased pulmonary vascular resistance (11 +/- 3.2 Wood units), whereas graft pacing showed significant augmentation of systolic pulmonary pressure by 54 +/- 12%, the mean pulmonary flow by 68 +/- 23%, and aortic pressure by 23 +/- 5% at a physiological range of central venous pressure (13.2 +/- 0.7 mmHg). Right heart function curve analysis confirmed marked augmentation of right heart performance, restoring almost normal pulmonary circulation. These functional benefits were sustained up to 4 hours in 4 animals until experiments were terminated.

CONCLUSIONS

Dynamic cardiomyoplasty in a modified Fontan procedure is a viable surgical option for univentricular heart, not a Fontan candidate.

Surgical therapy for heart failure

Today's healthcare delivery system is challenged with an escalating number of heart failure patients who have exhausted medical therapy and overwhelmed the limits of organ transplantation. Scientific and technological advances over the last 20 years have now brought new surgical options to this vast patient population, ranging from ventricular restoration surgery to surgical gene therapy and beyond. This article reviews the myriad of surgical options that are available to these patients, their benefits and shortcomings, as well as potential future directions.

Evolution in experimental Fontan circulation: a review

Experimental right heart bypass operations have influenced the evolution of current application of the Fontan procedure. In this review, we summarize the evolution and progress of the experimental Fontan operation (FO) and discuss the questions raised so far. The evolution and progress of the experimental FO is analyzed in this review by collecting data retrieved from English literature research. The establishment of Fontan circulation on an experimental animal model is extremely difficult and until today, a chronic experimental model has never been described. Computational fluid dynamics (CFD) has played a significant role in the investigation of the hemodynamic characteristics of the FO and has been applied to the design and integration of the procedure. CFD was also employed to evaluate the performance of assisted Fontan circulation. Accumulated experience from the experimental studies and clinical practice, in combination with the cooperation of different fields in medicine and positive sciences, are definitely expected to help the evolution furthermore.

Cardiac side population cells: moving toward the center stage in cardiac regeneration

Over the past decade, extensive work in animal models and humans has identified the presence of adult cardiac progenitor cells, capable of cardiomyogenic differentiation and likely contributors to cardiomyocyte turnover during normal development and disease. Among cardiac progenitor cells, there is a distinct subpopulation, termed "side population" (SP) progenitor cells, identified by their unique ability to efflux DNA binding dyes through an ATP-binding cassette transporter. This review highlights the literature on the isolation, characterization, and functional relevance of cardiac SP cells. We review the initial discovery of cardiac SP cells in adult myocardium as well as their capacity for functional cardiomyogenic differentiation and role in cardiac regeneration after myocardial injury. Finally, we discuss recent advances in understanding the molecular regulators of cardiac SP cell proliferation and differentiation, as well as likely future areas of investigation required to realize the goal of effective cardiac regeneration.

Autobionics: a new paradigm in regenerative medicine and surgery

The concept of bionics was developed 50 years ago and represented the development of engineering and technology based on natural biological systems. Traditional applications of bionics in healthcare include artificial bionic organs that apply engineering principles to replace or augment physiological functions by integrating electronic, mechanical or electromechanical components to inherent body tissues/organs (we term this as 'exobionics'). Recently, there has been a new wave of bio-inspired treatments that act through the reorganization of the existing biological organs in an individual to enhance physiology. Here, the technology does not replace biological tissue, but rather applies engineering principles to replace or augment physiological functions by the rearrangement and manipulation of inherent tissue/organs; we term this autobionics. Examples include: dynamic cardiomyoplasty (artificial heart pump using skeletal muscle), the Ross procedure (pulmonary autograft), dynamic graciloplasty (artificial sphincter) and metabolic gastric bypass (rearranging the gastrointestinal tract to modify gut- and pancreatic-hormone release). Autobionic therapies can be classified into dynamic, static and metabolic procedures. This results in tissue redesignation (one tissue used in place of another), tissue replacement and systems reorganization (rearranging inherent organ/tissue anatomy). In some cases autobionic procedures can enhance physiological function beyond normality and represents a new era in bio-inspired versatility.

Impact of valves in a biomechanical heart model assisting failing hearts

Experimental valveless muscular blood pumps (biomechanical hearts) in goats can pump more than 1 L.min(-1), but due to a high pendulum volume, no significant flow contribution to the circulation is gained. Thus valved and valveless biomechanical hearts were compared for efficacy. Heart failure was induced in 5 adult Bore goats by repeated intracoronary embolization. A valved and balloon-equipped pumping chamber was integrated into the descending aorta, simulating standard biomechanical circulatory support. The valveless biomechanical heart supported a failing heart with a baseline cardiac output of 2,670 +/- 710 mL.min(-1) by contributing additional flow of 113 +/- 37 mL.min(-1). The biomechanical heart model incorporating an outlet valve offered an additional 304 +/- 126 mL.min(-1), and the use of 2 valves significantly enhanced pulmonary blood flow by 1,235 +/- 526 mL.min(-1). The use of 2 valves in biomechanical hearts seems to be essential to achieve adequate circulatory support. Double-valved biomechanical hearts driven by an appropriate skeletal muscle ventricle may contribute to the therapy of heart failure.

Bio-technologies for a glandular stem cell cardiomyopexy

The glandular stem cell cardiomyopexy should become a treatment option for end-stage heart failure. It combines an expected regenerative potential of transformed adult glandular stem cells into cardiomyocytes within the myocardium or onto the myocardium of the recipient and the potential of a hypercapillarized latissimus dorsi muscle (LDM) wrapped around the heart for stem cell nutrition and girdling.

Dynamic cardiomyoplasty using artificial muscle

Dynamic cardiomyoplasty using latissimus dorsi muscle was previously used to compensate for congestive heart failure. Now, however, this method is not acceptable because the long-term result was not as expected owing to fatigue of the skeletal muscle. BioMetal fiber developed by Toki Corporation is one of the artificial muscles activated by electric current. The behavior of this fiber is similar to that of organic muscle. We made an artificial muscle like the latissimus dorsi using BioMetal fiber and tested whether we could use this new muscle as a cardiac supporting device. Testing one Biometal fiber showed the following performance: practical use maximal generative force was 30 g, exercise variation was 50%, and the standard driving current was 220 mA. We created a 4 x 12-cm tabular artificial muscle using 8 BioMetal fibers as a cardiac support device. We also made a simulation circuit composed of a 6 x 8-cm soft bag with unidirectional valves, reservoir, and connecting tube. The simulation circuit was filled with water and the soft bag was wrapped with the artificial muscle device. After powering the device electrically at 9 V with a current of 220 mA for each fiber, we measured the inside pressure and observed the movement of the artificial device. The artificial muscle contracted in 0.5 s for peak time and squeezed the soft bag. The peak pressure inside the soft bag was measured as 10 mmHg. Although further work will be needed to enhance the speed of deformability and movement simulating contraction, we conclude that artificial muscle may be potentially useful as a cardiac assistance device that can be developed for dynamic cardiomyoplasty.

The circumferential loading of a direct cardiac compression assist device

Heart disease is the developed world's largest killer. Transplantation of the failing heart remains the most effective treatment currently employed, but demand far exceeds donor supply. In a bid to address this imbalance, the use of mechanical circulatory support has been explored since the mid-1960s. This paper utilizes one such device, which achieves assistance by mechanically compressing the epicardial surface of the failing heart. The circumferential normal loading of the device is investigated, showing how frictional effects inherent to the device's operation affect localized surface pressure. Results showed that as distance from the device's actuator increased, assistive systolic force reduced, whilst device constriction to ventricular filling detrimentally increased. Active device relaxation was shown to limit the diastolic effect outlined above, providing the simulated diseased heart with an improved cardiac output. The results also raise questions concerning device in-vivo positioning and short-comings with the current heart simulator.

Effect of a Flexible Ventricular Restraint Device on Cardiac Remodeling after Acute Myocardial Infarction

The effects of a flexible ventricular restraint device on left ventricular (LV) dilatation and hypertrophy after transmural infarction are examined in an ovine model. Left ventricular remodeling and dilatation occurs after extensive myocardial infarction. A flexible ventricular restraint made from a nitinol mesh was evaluated in adult female sheep (n=14). Cardiac magnetic resonance imaging scans and hemodynamic measurements were completed before and 6 weeks after anterior myocardial infarction. Treatment animals (n=7) received passive ventricular restraint concurrently with LV infarction; the others (n=7) served as controls. Increases in LV end-diastolic volume index were significantly less in the restraint group than in controls (0.20+/-0.41 vs 0.83+/-0.50 ml/kg, p<0.03). End-systolic volumes increased less in treatment animals (0.43+/-0.28 vs 0.90+/-0.38 ml/kg, p<0.03). Control hearts showed an increase in LV mass after infraction, whereas LV mass decreased in restrained hearts (0.14+/-0.19 vs -0.25+/-0.36 g/kg, p<0.03). Hemodynamic studies showed similar changes after infarction for the control and the device group. Gross and microscopic examination showed no device-induced epicardial injury. A flexible ventricular restraint device attenuated remodeling after acute myocardial infarction in sheep.

Application of Animal Models: Chronic Electrical Stimulation-Induced Contractile Activity

Unilateral, chronic low-frequency electrical stimulation (CLFS) is an experimental model that evokes numerous biochemical and physiological adaptations in skeletal muscle. These occur within a short time frame and are restricted to the stimulated muscle. The humoral effects of whole body exercise are eliminated and the nonstimulated contralaterai limb can often be used as a control muscle, if possible effects on the contralateral side are considered. CLFS induces a fast-to-slow transformation of muscle because of alterations in calcium dynamics and myofibrillar proteins, and a white-to-red transformation because of changes in mitochondrial enzymes, myoglobin, and the induction of angiogenesis. These adaptations occur in a coordinated time-dependent manner and result from altered gene expression, including transcriptional and posttranscriptional processes. CLFS techniques have also been applied to myocytes in cell culture, which provide a greater opportunity for the delivery of pharmacological agents or for the application of gene transfer methodologies. Clinical applications of the CLFS technique have been limited, but they have shown potential therapeutic value in patients in whom voluntary muscle contraction is not possible due to debilitating disease and/or injury. Thus the CLFS technique has great value for studying various aspects of muscle adaptation, and its wider scientific application to a variety of neuromuscular-based disorders in humans appears to be warranted. Key words: skeletal muscle, muscle plasticity, endurance training, mitochondrial biogenesis, fiber types

Muscle and Myocutaneous Flaps in Reconstructive Surgery of Thoracic Defects

Reconstructive surgery of thoracic defects presents a challenge for the surgeon. With defects of different aetiology and the need for precise localisation of the area to be treated, a broad range of experience is required. We present our interdisciplinary experience in dealing with full thickness thoracic wall defects and intrathoracic cavities. The latissimus dorsi muscle as well as the pectoralis major muscle and their covering skin are the most commonly used flaps in covering an intrathoracic or extrathoracic defect. They have the advantage of being easily and safely dissected. Other flaps such as the greater omentum, serratus anterior, the transverse rectus abodominal muscle (TRAM), and the filet of the arm are less frequently used. Indications and applications of these flaps are reviewed. Our interdisciplinary surgical treatment of thoracic wall defects allows optimal operative excision and reconstruction as well as giving best functional and aesthetic results for the patients.

Reverse remodeling by net cardioplasty in a model of dilated cardiomyopathy: results of an animal study

AIM

End-stage heart failure is a growing clinical problem with only a few satisfactory therapeutical options. Dilated cardiomyopathy (DCM) is associated with a progressive decline in cardiac function. Our hypothesis was to arrest this worsening of cardiac function by mechanically containing the dilated heart with a special net.

METHODS

In 16 pigs (50+/-7 kg) DCM congestive heart failure was initiated by rapid ventricular pacing (220 b/m). In series 1 (n=8) a polyester net was placed around both ventricles before pacing was induced, whereas in series 2 (n=8) ventricular wrapping was performed when DCM was established.

RESULTS

Comparing hemodynamic data before re-operation of group 11-animals, the decrease of CO and dp/dt(max) was significantly lower in series 1 than in series 2 compared to the baseline values before pacing (CO: series 1:-22.6+/-3.3%, series 2:-52.4+/-6.4%, p<0.05; dp/dt: series 1: +16.4+/-2.8%, series 2: -51.5+/-5.9%, p<0.05). In series 2, after net implantation, we could furthermore show that deterioration of the animal stopped and hemodynamic data improved significantly in the following 2 weeks (CO: +62.9+/-10.5% and dp/dt +37.0+/-6.8%).

CONCLUSION

Ventricular containment with a polyester net seems to be a therapeutic option in cardiac insuffiency caused by ventricular dilation. This cardioplasty induced a reverse remodeling of the dilated hearts with a significant improvement in diastolic and systolic ventricular function.

Autologous muscle transfer for reconstruction of the lower urinary tract

The recent experimental results of using functioning muscle transfer to the bladder have been shown to be useful for some clinical indications. LDDM proved to be a viable option for the treatment of patients with an acontractile bladder due to traumatic or congenital lower motor neuropathy. A logical development for complete bladder substitution would be to combine the well-vascularized and contractile latissimus dorsi muscle transplant with cultivated and expanded autologous urothelial cells. A scaffolding, such as bioabsorbable polymer, alginate, or small intestinal sumucosa, may be useful to convey the in vitro-created urothelial layer onto the muscle and to avoid osteogenesis. Experimental studies are necessary, however, to rule out whether these materials induce fibrosis, leading to stiffness of the neobladder wall, and thereby reducing contractile function and voiding capability of the transferred muscle.

Nontransplant surgical options for congestive heart failure

Although advanced heart failure has been considered the main indication for heart transplantation, the increasing number of candidates and shortage of organs for transplantation, with accumulating waiting lists, has originated another look into more conventional surgery, previously considered of prohibitive risk. In fact, many cases are a result of anatomic lesions that can be corrected by conventional surgery, and in the past decade many surgical groups have obtained good and even excellent results in the treatment of aortic stenosis with low output, and in aortic and mitral regurgitation with severe left ventricular (LV) dysfunction. Also, ischemic and idiopathic dilated cardiomyopathy have been successfully treated by several types of LV remodeling surgery, with or without coronary grafting. Many of these procedures achieved excellent operative, medium-, and long-term results and survival, which match well those observed with cardiac transplantation, most often with advantages in the quality of life and, not unimportantly, in financial costs. For operated patients, especially those with ischemic cardiomyopathy, close follow-up for cardiac failure is extremely important in order to detect the right moment for heart transplantation, if it becomes necessary.

Passive external cardiac constraint improves segmental left ventricular wall motion and reduces akinetic area in patients with non-ischemic dilated cardiomyopathy

OBJECTIVE

To verify changes in left ventricular (LV) volumes and regional myocardial wall motion after implantation of a textile cardiac support device (CSD) for passive external constraint in non-ischemic dilated cardiomyopathy.

METHODS

In nine male patients participating in a non-randomized clinical trial LV volumes were determined and the segmental LV wall motion was studied by contrast-enhanced electron-beam CT in a sectionwise manner at three ventricular levels (base, middle and apex of ventricle) before and 32+/-6 months after CSD implantation. In 16 myocardial segments ejection fraction and wall thickening were measured semiautomatically after drawing the myocardial contours. The wall motion score index was calculated based on semiquantitative visual grading in each segment.

RESULTS

The global LV volumes decreased significantly from 304.3 +/- 90.9 to 231.5 +/- 103.9 ml at end-diastole and from 239.7 +/- 83.7 to 164.0 +/- 97.7 at end-systole (P<0.05). Overall ejection fraction increased from 14.8 +/- 8.2 to 25.7 +/- 17.1% (P<0.05). A segment-by-segment analysis demonstrated a significant increase of regional ejection fraction in the basal myocardium as well as in the mid-inferior, mid-inferolateral, and mid-anterolateral myocardium. Overall wall thickening increased from 16.4 +/- 13.3 to 24.2 +/- 18.1% (P<0.05), but without significant differences in a segment-by-segment comparison. The mean wall motion score index improved from 2.70 +/- 0.26 to 2.20 +/- 0.71 (P<0.05), with an increased wall motion in eight (89%) patients. A section-by-section analysis demonstrated significantly improved wall motion in the inferior and lateral segments at each ventricular level. Postoperatively, the number of akinetic and markedly hypokinetic segments decreased significantly (P<0.05) from 56 (39%) to 26 (18%) and from 76 (53%) to 56 (37%), respectively.

CONCLUSION

CSD implantation improves segmental wall motion, predominantly in the inferior and lateral myocardium, and reduces the number of akinetic and hypokinetic segments.

Dynamic cardiomyoplasty as a biomechanic bridge to heart transplantation

We report a heart transplantation that was done 4 years after a dynamic cardiomyoplasty operation. The patient was a 42-year-old man. Radionucleide ventriculography with technetium 99 m revealed an ejection fraction of 18%. In July 1997 he had undergone a dynamic cardiomyoplasty operation. At the first postoperative month the left ventricular ejection fraction was 35%. In September 2000 he presented with heart failure symptoms. In May 2001 he had undergone heart transplantation. Postoperative course was uneventful. The failure of cardiomyoplasty was probably caused by degeneration of the latissimus dorsi muscle. In this case we have learned that muscle viability is lost within 4 years after dynamic cardiomyoplasty and heart transplantation is still an option for those patients.

"Demand" stimulation of latissimus dorsi heart wrap: experience in humans and comparison with adynamic girdling

BACKGROUND

Questionable systolic assistance and latissimus dorsi (LD) muscular degeneration as a result of continuous electrical stimulation constitute important drawbacks to dynamic cardiomyoplasty. To avoid full transformation of the LD and thereby cause better systolic assistance, a new stimulation protocol was developed. Fewer impulses per day are delivered so that the LD wrap has daily periods of rest (demand), based on a heart rate cutoff. We describe our experience of demand dynamic wrapping by discriminating between patients with active systolic assistance and those with a passive girdle effect (adynamic-girdling).

METHODS

Fourteen patients with primary dilated cardiomyopathy (13 men, 1 woman; mean age, 58.2 +/- 5.8 years; 12 sinus rhythm, 2 atrial fibrillation) underwent dynamic cardiomyoplasty between 1993 and 1996 as well as the demand protocol at different intervals. Clinical, echocardiographic, mechanographic, and cardiac invasive assessment records, as well as cardiovascular events (death and arrhythmias), were retrospectively reviewed. The patients were divided into two groups on the basis of the mechanographic measurement of speed of contraction of the heart wrap, as measured by tetanic fusion frequency analysis before starting demand stimulation: demand dynamic wrapping patients with fast LD (high tetanic fusion frequency, 7 patients), and adynamic-girdling patients with slow LD contraction times (low tetanic fusion frequency, 7 patients). It was assumed that in adynamic-girdling patients dynamic assistance was virtually absent, so the wrapping acted only as a passive constraint wall.

RESULTS

The two groups were comparable for sex, age, dilated cardiomyopathy cause, New York Heart Association class, and left ventricular ejection fraction at the start of the demand protocol period. After a mean duration of follow-up of 41.4 +/- 21.1 months (range, 23 to 69 months), the demand dynamic wrapping group showed improved New York Heart Association class (1.14 +/- 0.34 versus 2.07 + 0.18; p = 0.0004), higher values of left ventricular ejection fraction (34.6 +/- 8.0 versus 26.5 +/- 3.1; p = 0.005) and LD wrap tetanic fusion frequency (38.3 +/- 5.88 versus 24.3 +/- 2.93; p = 0.002), and a better survival (85.7% versus 28.6%; p = 0.037) than the adynamic-girdling group.

CONCLUSIONS

Demand dynamic wrapping offers good results in terms of fewer cardiovascular events and greater survival. When compared with the passive constraint effect of LD muscle, demand dynamic wrapping proved to be more effective.

Orthotopic cardiac transplantation 30 months after successful dynamic cardiomyoplasty

Reports of cardiac transplantation after successful cardiomyoplasty are rare. We report the case of a 63-year-old man with intractable heart failure who underwent successful orthotopic cardiac transplantation 30 months after dynamic cardiomyoplasty.

A review of the concept of circulatory bioassist focused on the "new" demand dynamic cardiomyoplasty: the renewal of dynamic cardiomyoplasty?

After the initial enthusiasm, the dynamic cardiomyoplasty lost its reputation owing to the poor long-term results, caused by the muscular degeneration subsequent to chronic continuous electrical stimulation of the latissimus dorsi. An activity-rest stimulation protocol that avoids full transformation of the skeletal muscle, maintaining muscular properties over time, has been successfully tried. This "demand" stimulation protocol showed in humans good results improving NYHA class, ejection fraction value, and survival. The discussion about the capability of this and a unique kind of cardiocirculatory bioassist is due to be reopened. In fact, heart transplant, percutaneous circulatory-supporting device, multisites stimulation therapy, and total artificial heart have some drawbacks, one of which is the economic cost. In developing countries the more economic demand dynamic cardiomyoplasty may still play a role.

Effects of direct mechanical ventricular assistance on regional myocardial function in an animal model of acute heart failure

Direct mechanical ventricular assistance (DMVA) improves hemodynamics in failing hearts without complications associated with a blood/device interface. Epicardial Doppler displacement transducers provide exact measurements of tissue displacement and regional myocardial function (RMF). An in vivo porcine model of acute heart failure was used to examine the effects of DMVA on RMF, which have not been reported before. In 8 anesthetized pigs cardiac output (CO), left ventricular pressure (LVP), aortic blood pressure (BP), systolic contractility (dp/dt max), and systolic wall thickening fraction (WT%) were measured. A multichamber pump system (IMPS) surrounding the left ventricle was implanted and the measurements were repeated. Then acute heart failure was induced by beta-blockade, resulting in a decline of all measured parameters to more than 30% compared to baseline values. In the further course of the experiment, repeated measurements were taken at several intervals with and without DMVA by the implanted device. The IMPS implantation caused no significant hemodynamic changes. Under conditions of acute heart failure DMVA improved LVP (46 +/- 7 to 81 +/- 9 mm Hg), dp/dt max (532 +/- 207 to 744 +/- 361 mm Hg/s), CO (1.5 +/- 0.1 to 1.9 +/- 0.5 L/min) and WT% (19 +/- 7% to 32 +/- 8%). Left ventricular myocardium not directly assisted by external pressure application showed improved regional myocardial function during DMVA. We conclude that DMVA is capable of improving hemodynamics due to extrinsic compression. It also enhances the remaining myocardial function of the failing heart, which might lead to myocardial recovery. These synergistic effects are considered responsible for the high efficiency shown by the IMPS in previous investigations.

Demand dynamic bio-girdling in heart failure: improved efficacy of dynamic cardiomyoplasty by LD contraction during aortic out-flow

PURPOSE

The value of dynamic cardiomyoplasty has been brought into question by the disappointing results produced by slow contraction-relaxation cycle and possibly degeneration of the latissimus dorsi muscle (LD) secondary to temporary tenotomy and chronic daily electrical stimulation. Objective of our study is to determine whether daily periods of rest introduced by demand stimulation in the continuous contraction protocol produce systolic assistance and improve clinical results.

METHODS

Twelve dynamic cardiomyoplasty patients (mean age 58.2 +/- 5.8 years, M/F=11/1, sinus rhythm/atrial fibrillation=11/1) with dilated myocardiopathy were enrolled in an unrandomized trial of Demand Dynamic Heart Bio-Girdling in a public regional teaching hospital. Periods of LD inactivity, each lasting several hours, were introduced daily on a heart rate-based demand regime. To avoid full transformation of LD, fewer impulses per day were delivered, daily providing the LD with long periods of rest (Demand light stimulation). The contractile properties were measured by transcutaneous non-invasive LD tensiomyogram interrogation (LD tensiomyogram). Bio-Girdle activation was synchronized to heart beat by combining tensiomyogram and echocardiography. Clinical, echocardiographic and hemodynamic records, as well as aortic flow measurements by Doppler aortic flow wire were taken during the follow-up.

MAIN FINDINGS

Mean duration of the demand stimulation follow-up was 40.2+13.8 months. At five years, "Demand stimulation" shows: 1) no operative death; 2) 83% actuarial survival; 3) highly significant 47.4% decrease of the NYHA class (from 3.17 +/- 0.38 to 1.67 +/- 0.77, p=0.0001); 4) 41.6% improvement of LVEF (from 22.6 +/- 4.38 to 32.0 +/- 7.0, p=0.001); 5) 7.5 +/- 3.0% increase in aortic flow velocity peak in assisted vs. unassisted beats, and 6) preservation of LD from slowness (TFF value 33 +/- 7.86 at follow-up versus 15.8 +/- 11.1 Hz just before switching from continuous to demand stimulation, p=0.0001) and muscle degenerative atrophy.

CONCLUSIONS

In dynamic cardiomyoplasty the demand light stimulation maintains LD contraction properties over time, produces effective systolic assistance, and improves clinical results. Demand dynamic bio-girdling is a safe and effective treatment for end-stage heart failure in selected patients.

Cardiocirculatory bio-assist: is it time to reconsider demand dynamic cardiomyoplasty? Review and future perspectives

In the last 15 years, dynamic cardiomyoplasty has remained an experimental procedure even after the enthusiastic short- and mid-term results, mainly because of the disappointing long-term outcome caused by muscular degeneration secondary to chronic continuous electrical stimulation of the latissimus dorsi. In Italy, a group of muscular pathologists, cardiologists, and cardiac surgeons conducted an experiment of an activity-rest stimulation protocol in humans that should avoid complete transformation of the skeletal muscle, maintaining its properties overtime. This "demand" stimulation protocol gave good results, improving New York Heart Association class, ejection fraction value, and survival. Even though dynamic cardiomyoplasty was excluded from the recent international guidelines for the management of heart failure, the discussion on the ability of this unique kind of cardiocirculatory bio-assistance is due to be reopened, thanks to the results of the new stimulation protocol. Heart transplantation, circulatory supporting devices, multisite stimulation therapy, and the total artificial heart are not always and in all countries the best solutions: the great economic cost, the numerous contraindications, the need for immunosuppression and antithrombotic therapy, and the troublesome follow up constitute important drawbacks. For patients in whom transplant surgery cannot be performed, as well as in developing countries, the nonprohibitively expensive demand dynamic cardiomyoplasty may still play a role.

Systematic review of dynamic graciloplasty in the treatment of faecal incontinence

Background

The aim of this systematic review was to compare the safety and efficacy of dynamic graciloplasty with colostomy for the treatment of faecal incontinence.

Methods

Two search strategies were devised to retrieve literature from the Medline, Current Contents, Embase and Cochrane Library databases up until November 1999. Inclusion of papers depended on a predetermined protocol, independent assessments by two reviewers and a final consensus decision. English language papers were selected. Acceptable study designs included randomized controlled trials, controlled clinical trials and case series. Forty papers met the inclusion criteria. They were tabulated and critically appraised in terms of methodology and design, outcomes, and the possible influence of bias, confounding and chance.

Results

No high-level evidence was available and there were no comparative studies. Mortality rates were around 2 per cent for both graciloplasty and colostomy. Morbidity rates reported for graciloplasty appear to be higher than those for colostomy. Dynamic graciloplasty was clearly effective at restoring continence in between 42 and 85 per cent of patients, whereas colostomy is, by its design, incapable of restoring continence. However, dynamic graciloplasty is associated with a significant risk of reoperation.

Conclusion

While dynamic graciloplasty appears to be associated with a higher rate of complications than colostomy, it is clearly a superior intervention for restoring continence in some patients. It is recommended that a comparative, but non-randomized, study be undertaken to evaluate the safety of dynamic graciloplasty in comparison to colostomy, and that the procedure should be performed only in centres where it is carried out routinely.

The surgical treatment of heart failure. A new frontier: nontransplant surgical alternatives in heart failure

Heart failure may affect 500,000 new people each year. Heart transplantation has leveled off at approximately 2,500-3,000 cases per year in the United States. Thus, new nontransplant surgical alternatives may be necessary to treat many of the patients who progress to intractable Class III, or especially Class IV heart failure. In addition to left ventricular assist devices, other operations have been used and are now being developed for this purpose. These include left ventricular resection (Batista operation), mitral valve repair, autologous skeletal muscle cardiac assist, splint and compression devices, as well as left ventricular reconstruction by the Dor procedure. All of these procedures have been, and are currently being, evaluated for the surgical treatment of congestive heart failure and they will be reviewed in this article. Although many appear very promising, ongoing trials and retrospective reviews will be increasingly necessary to vigorously define which of the nontransplant surgical alternatives are the best procedures going forward for the large numbers of patients with congestive failure.

An alternative to left ventricular volume reduction

BACKGROUND

Left ventricular (LV) remodeling leading to ventricular dilatation is ultimately a maladaptative process according to the law of Laplace. To counteract the wall stress increase, a new concept of reducing the LV cavity radius by changing the LV globular shape to a bilobular one through the insertion of transventricular splints has emerged. This procedure is tested in a model of congestive heart failure.

METHODS

A bovine model was used (n = 9). Following splint insertion through a sternotomy, boluses of 2 liters of crystalloid were injected. After every bolus, hemodynamic measurements were performed without and with the splints tightened to a 10% and 20% stress level reduction, respectively. Comparisons between the 3 measurements were performed with analysis of variance test (p < 0.05).

RESULTS

Splint tightening significantly reduced right and left heart pressures for central venous pressure (CVP) >10 mm Hg (CVP: 14.7 +/- 5.2, 12.1 +/- 5, 10.6 +/- 4.7 mm Hg, p < 0.001 for baseline, 10% and 20% stress level reduction, respectively; mean pulmonary artery pressure: 33.5 +/- 4.7, 31 +/- 4.4, 29.4 +/- 5.1 mm Hg, p < 0.001; pulmonary capillary wedge pressure: 20.5 +/- 2.8, 18.9 +/- 3.3, 17.5 +/- 3.1 mm Hg, p < 0.001). The same holds true for cardiac output (6.5 +/- 1.6, 6.7 +/- 1.4, 6.8 +/- 1.7 liter/minute, p < 0.001), whereas heart rate and mean arterial pressure were not affected. The systemic and pulmonary resistances did not vary significantly throughout the procedure. Importantly, none of the hemodynamic parameters worsened at any stage with the splints.

CONCLUSIONS

In this model, hemodynamic parameters are improved with the splints for higher values of CVP, supporting the concept of reshaping the remodeled LV. This technique has the potential to improve patients with congestive heart failure.

Perioperative hemodynamic and geometric changes of the left ventricle during cardiomyoplasty in goats with dilated left ventricle

OBJECTIVE

Clinical data have suggested the occurrence of temporary short-term deterioration of the heart following cardiomyoplasty. The purpose of this study was to monitor the short-term hemodynamic effects of cardiomyoplasty in a goat model of a dilated left ventricle, using conductance catheters (ie, pressure-volume loops) and cardiac output measurements.

METHODS

Eight female goats underwent acute cardiomyoplasty 8 to 12 weeks after left ventricular (LV) dilatation was induced by a carotid jugular arteriovenous shunt. The cardiomyoplasty procedure was monitored using a Swan-Ganz catheter for cardiac output measurements and a 12-electrode (dual-field) conductance catheter to LV pressure-volume loops.

RESULTS

After wrapping the heart with the latissimus dorsi muscle, there was a significant reduction in both cardiac output and LV end-diastolic volume (LVEDV) at 10 min. Partial recovery was observed 45 min later.

CONCLUSION

A decrease in both cardiac output and LVEDV was observed following myocardial wrapping. This may explain some of the perioperative and postoperative morbidity and mortality observed following cardiomyoplasty.

Improved viability of latissimus dorsi muscle grafts after electrical prestimulation

Surgical mobilization of the latissimus dorsi muscle (LDM) produces fiber degeneration, particularly in the distal part of the graft, that may compromise its function in clinical applications such as dynamic cardiomyoplasty. In five rats, the left LDM was stimulated continuously at 10 HZ. After 5 weeks, vessels perforating the chest wall were divided and the left LDM was mobilized as a pedicle graft based on the thoracodorsal artery. Twenty-four hours later, animals were killed and left and right LDMs were incubated with the vital stain nitroblue tetrazolium. Five control rats underwent a similar procedure without prestimulation. Mobilization of the LDM resulted in a loss of viability in the distal third of the muscle graft. This was reduced significantly by prestimulation (P = 0.006). Blood flow to the distal LDM graft is known to be augmented by electrical stimulation in situ before mobilization; the present results show that there is an associated enhancement of viability. The clinical implications of this finding are discussed.

Cardiomyoplasty: ventricular reconstruction after tumor resection

OBJECTIVE

Although cardiac transplantation has been performed for complete removal of ventricular tumors, complete surgical resection with ventricular reconstruction is desirable. Thus patients with benign tumors would probably be cured, and those with malignant tumors would have a better prognosis. In this study extensive and complete surgical resection of ventricular tumors is followed by anatomic and functional ventricular reconstruction with a dynamic cardiomyoplasty procedure.

METHODS

Seven patients (mean age, 32.7 years) underwent complete resection of ventricular tumors. Histologic types were distributed as follows: fibroma in 2 patients and sarcoma, lymphosarcoma, hemangioma, lipoma, and metastatic angiosarcoma, respectively, in the remaining 5 patients. Six of the patients were considered candidates for heart transplantation because of the extent of tumor invasion. Surgery consisted of 4 steps: (1) tumor resection; (2) coronary artery resection (when invaded by the tumor) and coronary artery bypass grafting; (3) valvular reconstruction (when possible) or replacement; and (4) ventricular wall reconstruction with a pericardial patch for closure of the ventricular defect (neoendocardium) covered by the electrostimulated latissimus dorsi muscle flap (neomyocardium).

RESULTS

All patients survived surgical intervention, but 2 late postoperative deaths are reported. Among the surviving patients, early complications played a major role in their postoperative course and consisted of arrhythmias, atrioventricular block necessitating a dual-chamber pulse generator, respiratory insufficiency, and heart failure. Two patients were assisted postoperatively with an intra-aortic balloon pump. On postoperative follow-up (mean, 72.4 +/- 8.5 months), an improvement in the patients' functional status was observed. Patients moved from a mean New York Heart Association functional class of 2.8 to a mean functional class of 1.2.

CONCLUSIONS

The excellent long-term evolution without recurrence, ventricular dysfunction, and/or thromboembolic complications implies that cardiomyoplasty could be recommended as an alternative to heart transplantation for the therapy of large ventricular tumors.

Reducing the vascular delay period in latissimus dorsi muscle flaps for use in cardiomyoplasty

Although the mechanism by which vascular delay benefits skin flaps is not completely understood, this topic has been extensively studied and reported on in the literature. In contrast, little has been documented about the effects of vascular delay in skeletal muscle flaps. Recent animal studies tested the effectiveness of vascular delay to enhance latissimus dorsi muscle flap viability for use in cardiomyoplasty and found that it prevented distal flap necrosis. However, these studies did not define the optimal time period necessary to achieve this beneficial effect. The purpose of this study was to determine how many days of "delay" can elicit the beneficial effects of vascular delay on latissimus dorsi muscle flaps. To accomplish this, 90 latissimus dorsi muscles of 45 male Sprague-Dawley rats were randomly subjected to vascular delay on one side or a sham procedure on the other. After predetermined delay periods (0, 3, 7, 10, and 14 days) or a sham procedure, all latissimus dorsi muscles were elevated as single pedicled flaps based only on their thoracodorsal neurovascular pedicle. Latissimus dorsi muscle perfusion was measured using a Laser Doppler Perfusion Imager just before and immediately after flap elevation. The muscles were then returned to their original vascular beds, isolated from adjacent tissue with Silastic film, sutured into place to maintain their original size and shape, and left there for 5 days. After 5 days, the latissimus dorsi muscle flaps were dissected free, scanned again (Laser Doppler Perfusion Imager-perfusion measurements), and the area of distal necrosis was measured using digitized planimetry of magnified images. The authors' results showed that delay periods of 3, 7, 10, and 14 days significantly increased (p < 0.05) blood perfusion and decreased (p < 0.05) distal flap necrosis when compared with sham controls. On the basis of these findings, the authors conclude that in their rat latissimus dorsi muscle flap model the beneficial effects of vascular delay are present as early as 3 days. If these findings also hold true in humans, they could be useful in cardiomyoplasty by allowing surgeons to shorten the amount of time between the vascular delay procedure and the cardiomyoplasty procedure in these very sick patients.

Girdling effect of adynamic cardiomyoplasty in a model of dilated cardiomyopathy

OBJECTIVE

The potential benefits of adynamic cardiomyoplasty remain unclear. We determined whether unstimulated skeletal muscle wrap alone prevents or attenuates progressive left ventricular dilation in a canine model of congestive heart failure produced by repeated intracoronary infusions of doxorubicin.

SUBJECTS AND METHODS

14 dogs were randomized in to 2 groups, 1 undergoing cardiomyoplasty (CMP group) and 1 that did not (CONT group). Intracoronary doxorubicin was administered weekly for 5 weeks to induce heart failure. Hemodynamic data was obtained before infusion and 5 weeks afterward. Echocardiography was done weekly.

RESULTS

Significant left ventricular dilation was observed in the CONT group--left ventricular end-diastolic diameter increased from 28.9 +/- 2.7 to 38.5 +/- 3.3 mm (p < 0.05). Significant left ventricular dilation was also observed in the CMP group--left ventricular end-diastolic diameter increased from 28.9 +/- 3.3 to 38.0 +/- 4.2 mm (p < 0.05). Dilation was slower in the CMP group than in the CONT group, however. Ejection fraction decreased from 58.0 +/- 13.8 to 29.9 +/- 13.7% in the CONT group, but was preserved from 56.0 +/- 8.8 to 51.9 +/- 10.3% in the CMP group.

CONCLUSIONS

Adynamic cardiomyoplasty reduces ventricular dilation associated with heart failure without exacerbating left ventricular dysfunction.

Restoring voluntary urinary voiding using a latissimus dorsi muscle free flap for bladder reconstruction

We present our data using innervated latissimus dorsi muscle (LDM) free flaps to assist acontractile bladder function. Twelve dogs were used. In group I (n = 3), the LDM flaps were elevated and wrapped around silicon reservoirs; in group II (n = 4), the LDM flaps were transferred into the pelvis and used to reconstruct bladders that had 50% of their detrusor muscle wall removed; group III (n = 5) was the same setup as group II but the bladder mucosa was also removed with 50% detrusor wall. The LDM flaps were electrically stimulated and electromyography, cystography, urodynamic, and hydrodynamic measurements were performed. In clinical studies, LDM flaps were used in 11 patients (age range, 9-68 years). Our animal studies demonstrated that LDM flaps are capable of generating pressures (190 cm H(2)O at 15 mL and 35 cm H(2)O at a 10 mL in group I at 6 months) to void the bladder. In group II, contractions were present after 9 months. Eight of 11 patients who underwent LDM free flap were able to void voluntarily and without catheterization. LDM flap activity was confirmed using ultrasonography/tomography. Our clinical studies indicated that contractile function can be restored using LDM free flaps.