Device-based left ventricular geometry change for heart failure treatment: developmental work and current status

Abstract Background: Device‐based left ventricular (LV) geometry change is a new concept in the treatment of heart failure that reduces LV wall stress and improves cardiac function by reducing effective LV radius. Ventricular geometry change is achieved by placement of three Myosplint® devices to bisect the LV and to create two smaller LV chambers. Methods and Results: Since the first animal experiment in June 1997, the Myosplint has been tested extensively in a series of animal studies using a pacing‐induced, canine dilated cardiomyopathy model. Device‐based LV geometry change decreased LV wall stress, improved systolic function, and maintained diastolic function, resulting in an improvement in myocardial energetics. An acute human feasibility study during heart transplant surgery was started in July 1999. While awaiting the arrival of the donor heart, the Myosplint was implanted in the recipient LV in 5 patients. The device was easily applied on a beating heart without complications related to the device or the procedure in any of the patients. LV wall stress was significantly decreased after tightening of the device. Clinical safety studies with chronic Myosplint implantation were begun in Germany in June 2000 and in the United States in February 2001. There have been a total of 21 patients receiving the implant without evidence of bleeding, muscle tearing, severe arrhythmia, or thrombus formation associated with the implant. Conclusions: Device‐based geometry change has been demonstrated to be practical, effective, and safe. (J CARD SURG 2003;18 (Suppl 2):S43‐S47)     

Alterations in left ventricular torsion in tachycardia-induced dilated cardiomyopathy

OBJECTIVE: Left ventricular torsion reduces transmural systolic gradients of fiber strain, and torsional recoil in early diastole is thought to enhance left ventricular filling. Left ventricular remodeling in dilated cardiomyopathy may result in changes in torsion dynamics, but these effects are not yet characterized. Tachycardia-induced cardiomyopathy is accompanied by systolic and diastolic heart failure and left ventricular remodeling. We hypothesized that cardiomyopathy would alter systolic and diastolic left ventricular torsion mechanics, and this hypothesis was tested by studying sheep before and after the development of tachycardia-induced cardiomyopathy. METHODS: Implanted miniature radiopaque markers were used in 8 sheep to measure left ventricular geometry and function, maximal torsional deformation, and early diastolic recoil before and after rapid ventricular pacing was used to create tachycardia-induced cardiomyopathy. RESULTS: All animals had significant heart failure with ventricular dilatation and remodeling. With tachycardia-induced cardiomyopathy, maximum torsion relative to control conditions decreased (1.69 degrees +/- 0.61 degrees vs 4.25 degrees +/- 2.33 degrees ), and early diastolic recoil was completely abolished (0.53 degrees +/- 1.19 degrees vs -1.17 degrees +/- 0.94 degrees ). CONCLUSIONS: Cardiomyopathy is accompanied by decreased and delayed systolic left ventricular torsional deformation and loss of early diastolic recoil, which may contribute to left ventricular dysfunction by increasing systolic transmural strain gradients and impairing diastolic filling. Analysis of left ventricular torsion with radiofrequency-tagging magnetic resonance imaging should be explored to elucidate the role of torsion in patients with cardiomyopathy.     

A more comprehensive left ventricular repair for severely dilated cardiomyopathy

We report a patient with cardiogenic shock due to severely dilated cardiomyopathy who underwent complex, but comprehensive left ventricle (LV) repair. Preoperative investigation showed marked LV dilatation, poor LV function, severe mitral and tricuspid regurgitation, and total occlusion of two coronary arteries. We urgently performed (1) modified Batista operation which preserves the LV apex, (2) septal anterior ventricular exclusion (SAVE) operation, (3) mitral annuloplasty, (4) tricuspid annuloplasty, and (5) coronary bypass. Postoperative evaluation revealed good graft flow, reduced LV dimension preserving the elliptical shape, improved LV function, and minimal MR. Twenty-six months postoperatively, the patient has minimum clinical symptoms (NYHA: I).     

Persistent abnormal left ventricular systolic torsion in dilated cardiomyopathy after partial left ventriculectomy

OBJECTIVE: Rotation of the left ventricular apex relative to the base, or left ventricular torsion, is related to myocardial contractility and structure and is a sensitive indicator of cardiac dysfunction. We have quantified left ventricular systolic rotation and torsion in patients with dilated cardiomyopathy before and after partial left ventriculectomy in an attempt to characterize the effects of this surgical procedure on ventricular ejection mechanics. METHODS: Magnetic resonance imaging with tissue tagging was performed before partial left ventriculectomy in 24 patients, 9 of whom underwent repeat imaging 3 months after surgery. Left ventricular rotation was quantified in each patient at three short-axis levels: apex, midventricle, and base. Torsion was defined as the difference between basal and apical rotation at any time. Results were subdivided for regional analysis at each level and related to cardiac function (ejection fraction, cardiac index, and velocity of circumferential fiber shortening). RESULTS: Before surgery, left ventricular rotation was regionally heterogeneous and abnormal in magnitude and pattern, and increased end-systolic torsion was associated with better cardiac function. After surgery, clinical indices of cardiac function showed improvement; however, rotation magnitude was unchanged at the apex and reduced at the base and midventricle, particularly in the anterior wall and septum. CONCLUSIONS: The pattern and magnitude of ventricular rotation were impaired by dilated cardiomyopathy. Left ventricular rotation and torsion were further diminished after partial left ventriculectomy, indicating that improvement in clinical indices of cardiac function was not reflective of an improvement in this measure of myocardial mechanics.     

Therapeutic left ventricular assist device and apheresis on dilated cardiomyopathy

Pathogenesis and therapies of dilated cardiomyopathy (DCM) have been discussed for a long time, but both of the ultimate answers are still unknown. In the last decade, the pathogenic role of immunological factors, such as cardiac autoimmune antibodies and cytokines, have been discussed attentively. This has led to one possible new therapy, immunoadsorption, which removes antibodies, and it has made a remarkable effect. However, there are other factors to remove. For the removal of cytokines and neurohormones, the most effective method is hemofiltration (HF). Also, double-filtration plasmapheresis (DFPP) removes immunoglobulin as well as low-density lipoprotein (LDL) and coagulation factors that may improve blood circulation, including the coronary arteries. Therefore, to eliminate all deteriorative factors, both apheresis therapies, HF and DFPP, should be performed. Due to the shortage of donor hearts, left ventricular assist systems (LVAD) have been used as a bridge to transplantation. It has now been reported that the total unloading of the left ventricle does not only maintain, but also recovers, the cardiac function, even from end-stage heart failure. However, the patients who have obtained a long-lasting recovery of cardiac function from an LVAD are still in a minority. To make this the majority, therapeutic LVAD should be combined with the apheresis therapies, DFPP and HF. We believe that this concept, a combination of HF and DFPP with therapeutic LVAD, will be the next generation of treatment that has a potential to postpone, or even avoid, heart transplantation.     

Significance of morphological and electrophysiological left ventricular restoration in idiopathic dilated cardiomyopathy

Treatment of non-ischemic dilated cardiomyopathy (NIDCM) remains a challenge. Morphological left ventricular (LV) restoration such as septal anterior ventricular exclusion (SAVE) can be effective in treating NIDCM; however, residual electrophysiological disorders such as atrioventricular and intraventricular conduction disturbances become apparent in the form of atrial fibrillation (AF) and LV dyssynchrony, which deteriorate postoperative LV function. Thus, the combination of morphological and electrophysiological LV restoration may further improve LV function. Here, we report the case of a patient with end-stage NIDCM complicated with AF and LV dyssynchrony, who was successfully treated with the combined use of SAVE, undersized mitral annuloplasty, left atrial (LA) Maze procedure with cryoablation, and postoperative biventricular pacing. This combination treatment was beneficial in restoring the sinus rhythm and LA and LV functions with improved and synergic wall motion by excluding the dyskinetic/akinetic area, downsizing the LV, resolving mitral regurgitation, and optimizing conduction and rhythm abnormalities. Notably, biventricular pacing was shown to be effective in resolving residual dyssynchrony between the septum and lateral wall after SAVE, wherein a firm, non-compliant Dacron patch was sutured to the septum.     

Early and mid-term results of left ventricular volume reduction surgery for dilated cardiomyopathy

OBJECTIVE: To evaluate structure-oriented left ventricular volume reduction surgery (LVVRS). The purpose of this study was to report the early and mid-term results of left volume reduction surgery for dilated cardiomyopathy (DCM). METHODS: We performed LVVRS on 29 patients with DCM. The age of the patient ranged from 8 to 73 years (mean 58 +/- 18 years). There were 19 male patients (63%). Twenty-three patients were ischemic, 5 were non-ischemic, and 1 had salcoidosis. Twenty-three patients were in New York Heart Association class III or IV. Fourteen patients underwent the Dor operation, 11 underwent a septal anterior ventricular exclusion operation, and 6 underwent a modified Batista operation. Fifteen patients underwent mitral annuloplasty and 2 patients had mitral valve replacement. All patients were divided into two groups, a Dor group (n = 14) and non-Dor group (n = 15). Postoperative early results and mid-term survival rate were compared between the two groups. RESULTS: Hospital mortality was 13.8% (4/29). The causes of death were low-output syndrome (n = 3) and septic shock (n = 1). Survival rate was 80% at 1 year and 72% at 3 years. Two-year survival rate of Dor and non-Dor groups were 69.8% and 93.8%, respectively (p = 0.099). CONCLUSIONS: Early and mid-term results of LVVRS were satisfied, and the non-Dor operation tended to be superior in mid-term survival to the Dor operation. Long-term follow-up is warranted.     

Cardiac recovery in dilated cardiomyopathy by unloading with a left ventricular assist device.

BACKGROUND: Lasting recovery from intractable end-stage dilated cardiomyopathy, which occurs with ventricular unloading, has recently been demonstrated in 5 patients. Here our extended clinical experience with the "weaning" concept is presented. METHODS: In 19 patients (23 to 65 years) with intractable end-stage dilated cardiomyopathy, ventricular assist devices were explanted after support periods of up to 26 months, when repeat off-pump studies had shown either restoration of cardiac function (left ventricular ejection fraction, > 45%) and dimensions (left ventricular internal diameter in diastole, < 55 mm) or partial recovery (left ventricular ejection fraction between 35% and 40%) with serious complications on the device. At the time of device placement left ventricular ejection fraction was below 20% and left ventricular internal diameter in diastole more than 64 mm and bridge-to-transplantation had been planned. RESULTS: Seven patients with persistently restored cardiac function for more than 8 months and 5 patients for less than 5 months after weaning were studied. Five patients with recurrent heart failure died within 4 to 8 months after explantation. Four patients had to be transplanted and 2 died for reasons unrelated to cardiac function. An individual optimal left ventricular ejection fraction and left ventricular internal diameter in diastole was reached before pump removal was actually conducted in all patients. These parameters gradually deteriorated until pump removal. CONCLUSIONS: Lasting recovery can be reached by ventricular unloading in a subset of patients with intractable end-stage dilated cardiomyopathy. Obviously, there is an individual optimum of recovery that cannot be further improved by prolonged unloading.     

Acute clinical deterioration in a patient with end-stage dilated cardiomyopathy and left ventricular thrombus formation

The case of a 17-year-old male patient with severe end-stage dilated cardiomyopathy and a large thrombus formation within the cavum of the left ventricle is reported. After an acute thrombectomia combined with a partial left ventriculectomy (Batista procedure), the patient was successfully treated with an appropriate left ventricular assist device (LVAD) system using a centrifugal nonocclusive pump (Biomedicus, Medtronic, Anaheim, CA, U.S.A.). Mechanical support was removed on Day 9, and the patient was discharged from the hospital on Day 19. The effectiveness of emergency mechanical support in patients with very unfavorable prognoses is discussed.     

Current perspectives of partial left ventriculectomy in the treatment of dilated cardiomyopathy.

OBJECTIVES: Partial left ventriculectomy has been performed as an alternative to heart transplantation in the treatment of severe cardiomyopathies. This investigation documents the clinical and left ventricular (LV) function effects of this procedure, associated, when necessary, with mitral insufficiency correction, in 43 patients with idiopathic dilated cardiomyopathy. METHODS: Eighteen patients were in New York Heart Association class III and 25 in class IV. Seven of them were operated in cardiogenic shock. The procedure was associated with mitral annuloplasty in 32 patients and mitral replacement in three. RESULTS: Nine patients (20.9%) died during the hospital period and the cause of death was associated with ventricular failure in seven patients. The other patients were followed up from 2 to 57 months (mean, 28.3 months). At 6 months of follow-up, eight patients were in functional class I, 13 in class II, three in class III and one patient was in class IV (P<0.001). On the other hand, nine patients died during the first 6 months and another six in the later postoperative period. The cause of late death was progressive heart failure in eight patients, and seven patients died because of arrhythmia related events. The actuarial survival was 58.1+/-7.5% at 1 year and 43.9+/-8.1% at 4 years of follow-up. Regarding ventricular function modifications, the LV diastolic volume decreased by around 25% and the LV ejection fraction increased from 17.8+/-4.7 to 22.3+/-7.9% (P<0.001), whereas significant changes in the cardiac index, stroke index and pulmonary pressures were also found 1 month after the operation. In the later follow-up, despite the maintenance of hemodynamic improvement, the LV diastolic volume tended to increase and returned to preoperative levels at 4 years, while a concomitant decrease in the LV ejection fraction was also observed. CONCLUSION: Partial left ventriculectomy associated with mitral insufficiency correction improves LV function and ameliorates congestive heart failure in patients with idiopathic cardiomyopathy. Otherwise, the LV function benefits seem to be restricted by the possibility of progressive LV redilatation. Furthermore, the clinical application of this procedure is limited by the high mortality observed in the first postoperative months and by the possibility of heart failure progression and arrhythmia related events at late follow-up.     

Effects of dynamic cardiomyoplasty on left ventricular performance and myocardial mechanics in dilated cardiomyopathy

We tested the hypothesis that dynamic cardiomyoplasty produces beneficial changes in the functional mechanics of the dilated, failing left ventricle. Chronic dilated cardiomyopathy was induced in seven mongrel dogs by rapid ventricular pacing (260 beats/min) for 3 to 4 weeks. After completion of the induction period, dynamic cardiomyoplasty was performed with the left latissimus dorsi muscle, paced synchronously with the R waves of the electrocardiogram (Medtronic SP1005). Instruments included an aortic flow probe, a left ventricular Millar pressure catheter, and piezoelectric sonomicrometric crystals on the left ventricle for measurements of wall thickness and minor and major axis dimensions. Data were obtained with the stimulator off and on. Statistical comparisons were made with Student's t test for paired data. Dynamic cardiomyoplasty increased the cardiac output of the failing heart (966 +/- 124 versus 1166 +/- 112 ml/min; p less than 0.01). Systolic shortening of both minor and major axis dimensions increased (3.1 +/- 0.3 versus 4.7 +/- 0.3 mm, p less than 0.01, and 4.6 +/- 0.3 versus 7.3 +/- 0.9 mm, p less than 0.05, respectively). Left ventricular end-diastolic pressure decreased by 16% (18 +/- 1 versus 15 +/- 1 mm Hg, p less than 0.01). Although skeletal muscle contraction increased the pressure development in the left ventricular chamber, mean systolic wall stress was diminished by concomitant changes in left ventricular dimensions (116,144 +/- 11,530 versus 101,268 +/- 7464 dynes/cm2, p less than 0.05). At end-systole, wall thickness increased (11.8 +/- 1.1 versus 12.7 +/- 1.1 mm, p less than 0.01), minor axis dimension decreased (51.3 +/- 1.4 versus 49.2 +/- 1.8 mm, p less than 0.01), and major axis dimension also decreased (85.6 +/- 3.3 versus 79.0 +/- 2.3 mm, p less than 0.05). Our detailed evaluation of left ventricular chamber mechanics suggests that dynamic cardiomyoplasty may have a role in ameliorating the functional and mechanical derangements associated with progression of dilated cardiomyopathy both by augmenting cardiac performance and by diminishing determinants of myocardial oxygen consumption. (All values are expressed as mean +/- standard error of the mean.)     

Transplantation of cryopreserved muscle cells in dilated cardiomyopathy: effects on left ventricular geometry and function

OBJECTIVE: Cell transplantation to prevent congestive heart failure in patients with inherited dilated cardiomyopathy might require the use of noncardiac donor cells unaffected by the genetic defect and cryopreservation to permit cell storage until the time of transplantation. However, the effects of cryopreservation on peripheral muscle cells harvested from a cardiomyopathic recipient and their subsequent ability to restore cardiac structure and function after transplantation are unknown. METHODS: Skeletal myoblasts and vascular smooth muscle cells from cardiomyopathic hamsters (delta-sarcoglycan-deficient BIO 53.58 hamster) and age-matched normal donor hamsters were isolated, expanded in culture, and cryopreserved. After reanimation in culture, cell morphology and growth rate were assessed and compared with values seen in noncryopreserved cells. A total of 4 x 10(6) previously cryopreserved skeletal myoblasts (n = 10) and vascular smooth muscle cells (n = 10) harvested from cardiomyopathic donors were then transplanted into the left ventricles of 17-week-old BIO 53.58 hamsters. Hearts injected with culture medium alone (n = 11) served as controls. Heart function was assessed 5 weeks after transplantation on a Langendorff apparatus, and left ventricular geometry was quantified by means of computerized planimetry. Staining with 5-bromo-2'-deoxyuridine identified the injected cells. RESULTS: Vascular smooth muscle cells from cardiomyopathic donors had an abnormal morphology and diminished growth rates in culture compared with vascular smooth muscle cells from normal donors. These markers of injury were exacerbated by cryopreservation. In contrast, vascular smooth muscle cells from normal donors and skeletal myoblasts from either cardiomyopathic or normal donors appeared normal in culture and were unaffected by cryopreservation. Both cryopreserved vascular smooth muscle cells and skeletal myoblasts from cardiomyopathic donors formed a viable muscle-resembling tissue that prevented wall thinning, limited left ventricular dilatation, and preserved global systolic function in hamsters with a genetic dilated cardiomyopathy. However, attenuation of cardiac remodeling and preservation of global heart function was greater after skeletal myoblast transplantation compared with vascular smooth muscle cell transplantation in parallel to the in vitro morphologic and growth characteristics of these cells. CONCLUSIONS: Cryostorage of healthy donor cells does not prevent the benefits of cell transplantation on limiting remodeling and preserving cardiac function in the failing heart. The health of donor cells in vitro predicts their subsequent benefits on cardiac structure and function after transplantation. Cryopreservation of donor cells might facilitate a clinically applicable and effective approach for ventricular restoration with cell-transplantation therapy for patients with inherited dilated cardiomyopathy.     

Anesthetic management of a patient with dilated cardiomyopathy for left ventricular pacing lead insertion under video-assisted thoracic surgery

A 54-year-old man with dilated cardiomyopathy treated with diuretics, alpha-beta blockers, antiarrhythmics for the previous 5 years, had the indication for biventricular pacing and was scheduled for placing of pacing leads in his left ventricular wall under video-assisted thoracic surgery. Preoperative tests revealed first degree A-V block with left bundle branch block and left ventricular dilation with an ejection fraction of 0.11 on echocardiography. Anesthesia was induced with ketamine and midazolam. Endotracheal intubation was facilitated by administration of vecuronium. Anesthesia was maintained with oxygen-sevoflurane and fentanyl. One lung ventilation was carried out during surgery and the arterial oxygen saturation was kept satisfactory with the intermittent insuffilation of oxygen to the non ventilated lung. The procedure was completed uneventfully while ventricular tachycardia was observed. Biventricular pacing increased the ejection fraction from 0.11 to 0.27. We conclude that any special monitoring such as TEE would be helpful to evaluate the cardiac function during the operation.     

Residual fibrosis affects a long-term result of left ventricular volume reduction surgery for dilated cardiomyopathy in a rat experimental study

Objectives: The aim of this study is to evaluate the relationship between left ventricular (LV) wall property and the results of LV volume reduction surgery (LVR) to treat dilated cardiomyopathy (DCM) in an experimental model. Methods: DCM was introduced in 18 Lewis rats by autoimmunization with cardiac myosin. Among them, 12 rats underwent LVR and the rest were served as controls. They were subjected to echocardiography and cardiac catheterization for dimensional and functional measurements. The animals were sacrificed 4 weeks after surgery, and the fraction of myocardial fibrosis was calculated in 4 divided parts of the LV wall. Results: Percent fibrosis varied widely from 4.7 to 45.2%. LV volume reduction surgery improved cardiac function immediately after surgery in all rats (E_max, 0.28±0.14 to 0.48±0.18 mmHg/μl; LV end-diastolic pressure, 21.0±6.1 to 13.3±5.1 mmHg, P<0.05, respectively). Four weeks later, 6 hearts remained in good shape with smaller LV end-diastolic dimension (Dd) than baseline values (LV Dd, 9.7±0.6 mm; fractional area change (FAC), 40.3±8.4%) and the other 6 had more redilation in diameter and more deterioration in function than baseline values (LV Dd, 10.9±0.6 mm; FAC, 25.8±6.9%; P<0.05, respectively). Percent fibrosis in the septum differed 11.1±3.4 vs. 27.8±2.8% between the two groups (P<0.01). There was a significant correlation between the ratio of LV redilatation after surgery and percent fibrosis in the septum (r=0.951, P<0.01). Conclusions: Although the initial benefit of LVR was confirmed, the long-term result was affected by the amount of residual fibrosis. This information suggests that surgical site selection is important to achieve a good result of LV restoration surgery for DCM.     

Partial left ventriculectomy in pediatric end-stage dilated cardiomyopathy

OBJECTIVE: Although a recent survey on pediatric cardiomyopathy in Japan showed that 48% of patients died despite the medical treatment, pediatric cardiac transplantation is not legal in Japan. We determined the feasibility of partial left ventriculectomy as an alternative to end-stage dilated cardiomyopathy. METHOD: We retrospective analyzed partial left ventriculectomy in 4 pediatric patients with end-stage dilated cardiomyopathy. RESULTS: In case 1, an 8-month-old girl underwent semiemergency partial left ventriculectomy. Her ejection fraction increased from 10% to 25%, and her condition improved initially, but she developed heart failure and underwent cardiac transplantation 6 months later in the US. In case 2, a 3-year-old boy developed severe heart failure 2 months after ventricular septal defect repair. Intensive medical therapy failed, so partial left ventriculectomy was done, which increased his ejection fraction from 15% to 35%. His condition is stable 35 months after surgery. In case 3, a 2-year-old girl with a chromosomal anomaly undergoing ventricular septal defect repair developed progressive heart failure 1 year later. Despite emergency partial left ventriculectomy, she died of hemoptysis 2 weeks postoperatively. In case 4, a 2-year-old girl developing progressive heart failure unresponsive to medical therapy after 10 months underwent elective partial left ventriculectomy and remains in stable condition 18 months postoperatively. CONCLUSION: Partial left ventriculectomy is appropriate for selected patients with end-stage dilated cardiomyopathy if medical therapy is not effective and heart transplantation is not possible.