Right latissimus dorsi cardiomyoplasty for left ventricular failure.

Recent experimental studies have shown that cardiomyoplasty using the right latissimus dorsi provides excellent hemodynamic augmentation. Based on these experimental findings, this procedure was performed in a 40-year-old man with a dilated cardiomyopathy after a large myocardial infarction. The patient tolerated the procedure well and has had marked functional improvement. Examination 6 months after operation demonstrated decreases in right atrial pressure, pulmonary capillary wedge pressure, and left ventricular end-diastolic volume. In addition, increases were noted in cardiac output, stroke volume, left ventricular stroke-work, right ventricular ejection fraction, and left ventricular ejection fraction. Because of this promising clinical result, we have started a series of right latissimus dorsi cardiomyoplasties for left ventricular failure.     

Paced latissimus dorsi used for dynamic cardiomyoplasty of left ventricular aneurysms

Two patients are described, each with a large left ventricular aneurysm and severe coronary artery disease, and each with an ejection fraction lower than 30% and in congestive heart failure. In both, the left latissimus dorsi (LD) muscle was used in the repair of the ventricular aneurysm because preoperative studies demonstrated that there was concomitant coronary artery disease, and there was a strong suggestion that resection of the entire aneurysm would seriously compromise the residual ventricular capacity. One patient had an 18-year history of coronary occlusion with two infarctions. A large, calcified ventricular aneurysm developed, and despite vigorous medical treatment, intractable congestive heart failure and angina persisted. The diffuse coronary artery disease made this patient a poor candidate for bypass grafting. The other patient sustained an acute myocardial infarction 5 months prior to operation. The left anterior descending coronary artery was totally occluded, and a large apical aneurysm developed along with an akinetic anterior wall and septum. After his heart attack, the patient had progressive dyspnea on exertion. Following operation in both patients, the transpositioned LD, then a component in the repair of the left ventricular wall, was electrically trained to synchronously contract with each systole, driven by a standard dual-chamber cardiac pacemaker. Steady improvement and a return to normal activities were observed in both patients. There was an indication of improved ejection fraction with synchronous contraction of the skeletal muscle.     

Bilateral latissimus dorsi cardiomyoplasty.

This study was undertaken to test the hypothesis that a bilateral latissimus dorsi cardiomyoplasty provides greater hemodynamic augmentation than a unilateral procedure. Two types of bilateral procedure and a left posterior cardiomyoplasty were tested in each of 8 mongrel dogs. R-wave synchronous muscle pacing was achieved with a programmable burst stimulator. Hemodynamic variables of stimulated beats were compared with those of a nonstimulated baseline using paired t tests. The effects of a double anterior muscle wrap were equal to a right anterior/left posterior configuration. Therefore, the data on the two types of bilateral procedure were combined and compared with the left wrap. Stimulation of the bilateral cardiomyoplasty resulted in significant increases in right ventricular pressure (44 +/- 3.1 versus 26 +/- 1.8), first derivative of right ventricular pressure (595 +/- 117 versus 196 +/- 14), pulmonary artery pressure (34 +/- 1.9 versus 23 +/- 1.6), left ventricular pressure (90 +/- 5.9 versus 69 +/- 5.3), first derivative of left ventricular pressure (1454 +/- 141 versus 1072 +/- 107), aortic pressure (80 +/- 5.4 versus 67 +/- 4.9), and peak aortic flow (9.4 +/- 1.1 versus 7.7 +/- 0.8) (p less than 0.05). Significant increases in all of these variables also occurred with stimulation of the left cardiomyoplasty, but the increases in right ventricular pressure, first derivative of right ventricular pressure, pulmonary artery pressure, and aortic pressure were larger for the bilateral than the left cardiomyoplasty. The bilateral and the left procedure can each augment systolic ventricular function. The bilateral procedure appears to have greater effects, especially on right ventricular function.     

A case of cardiomyoplasty with synchronous stimulated latissimus dorsi muscle

In December, 1988, a 57-year-old man sustained an acute myocardial infarction. He suffered from progressive cardiac failure, despite bed rest and intensive medical treatment. Finally, he developed hepatic and renal failure. Subsequent angiographic studies revealed the total occluded LAD (Seg. 6) and a large LV aneurysm. In January 1989, a left ventricular aneurysmectomy and cardiomyoplasty using the latissimus dorsi muscle were performed successfully. Two years after the operation, he is alive and well.     

Growth factors improve latissimus dorsi muscle vascularization and trophicity after cardiomyoplasty

BACKGROUND: Dynamic cardiomyoplasty consists of wrapping the electrostimulated latissimus dorsi muscle (LDM) around the failed heart. Partial ischemia followed by atrophy of the middle and distal part of the LDM were observed in 30% of clinical cases after LDM flap elevation from its origin. In the current study, we hypothesized that local administration of growth factors at the LDM/epicardial interface could improve muscle vascularization and trophicity. METHODS: In 24 sheep, dynamic cardiomyoplasty was performed using the left LDM. A multiperforated catheter was positioned at the LDM/epicardial interface for a weekly administration, during a 1-month period, of the following factors: basic fibroblast growth factor (bFGF, n = 6), vascular endothelial growth factor (VEGF, n = 6), and regenerating agent (RGTA, n = 6). Six sheep injected with phosphate-buffered saline (used for dilution of the growth factors) were used as a control group. At 3 months, angiographic, histologic, and histomorphometric studies were performed. RESULTS: Angiographic studies of the animals treated with growth factors demonstrated hypervascularization due to the development of new vessels. Histomorphometric and histologic studies showed a significant increase in the number of capillaries and arterioles (100 fields/muscle) in the groups treated with bFGF (443.0 +/- 101.2, p < 0.01), RGTA (293.2 +/- 29.3, p < 0.05), and VEGF (246.5 +/- 45.9, p < 0.05), as compared with the control group (81.5 +/- 11.4). A significantly lower atrophy score was observed in the groups treated with bFGF (1.4 +/- 0.18, p < 0.05), RGTA (1.59 +/- 0.17, p < 0.05), and VEGF (1.96 +/- 0.14, NS), as compared with the control group (2.48 +/- 0.16). CONCLUSIONS: Local administration at the heart/muscle interface of growth factors increases muscle vascularization and avoids muscle atrophy in an experimental cardiomyoplasty model, both of which are advantageous to the contracting LDM. The local growth factors delivery system used in this study appears efficient, easy to implant, and manipulate and safe.     

Demand dynamic cardiomyoplasty: mechanograms prove incomplete transformation of the rested latissimus dorsi

BACKGROUND: In dynamic cardiomyoplasty, standard stimulation produces high fatigue resistance but also undesirable dynamic characteristics of the latissimus dorsi (LD). Based on results of intermittent stimulation in animals we introduced demand stimulation, a lighter regimen of LD activity-rest stimulation, and the mechanogram, a noninvasive method to determine the contractile characteristics of LD wrap. METHODS: Surgery and standard stimulation was according to the technique of Carpentier and Chachques, demand stimulation and LD wrap mechanogram were as we previously described. The LD contraction is synchronized to heart systole by mechanogram and echocardiography, and extent of transformation by tetanic fusion frequency analysis. A total of 22 patients were studied to date. Data for the 8 subjects who attained 6-month follow-up are reported. Four of them were lightly stimulated from the conditioning period, whereas 4 others were converted to light and then demand stimulation after years of standard stimulation. Patients were followed up with respect to survival, functional class, hospital admission rate, medication used, cardiopulmonary exercise testing, and LD wrap mechanography. RESULTS: Latissimus dorsi wrap slowness reverses by the activity-rest regimen, even after years of standard stimulation (Tetanic fusion frequency of 11 +/- 2 Hz after standard stimulation vs 30 +/- 3 Hz after demand regimen, p < 0.0001). After demand dynamic cardiomyoplasty there are no deaths. Quality of life is substantially improved with significant reduction of heart failure symptoms (New York Heart Association class: preoperative 3.0 +/- 0.0, post-demand dynamic cardiomyoplasty 1.5 +/- 0.2, p < 0.0001). In the subgroup of patients lightly stimulated from LD conditioning, exercise capacity tends to increase over preoperative values more than 2 years after operation (VO2 max: preoperative 12.3 +/- 0.7 vs 16.6 +/- 1.7 post-demand dynamic cardiomyoplasty, p = 0.05). CONCLUSIONS: Demand stimulation and mechanography of the LD wrap are safe procedures that could offer long-term benefits of dynamic cardiomyoplasty to patients with pharmacologically intractable heart failure.     

Hydraulic pouches of canine latissimus dorsi. Potential for left ventricular assistance

We have studied the fatigue rates of hydraulic pouches constructed in the form of a multilayered conical spiral using the latissimus dorsi muscle of 17 beagles. The roles that electrical muscle conditioning and early interruption of collateral blood supply have in the prevention of pouch fatigue were evaluated. The length of time that a pouch could generate flow in a hydraulic test system was measured; afterload was set at 80 mm Hg and preload 24 mm Hg. Pouches (N = 3) fashioned from muscles subject to neither electrical conditioning nor a vascular delay generated an initial flow of 990 +/- 346 ml/min, but could sustain flow for only 2.3, 3.8 and 3.6 minutes. Pouches (N = 5) constructed with electrically unconditioned muscles after a vascular delay (median 3 weeks) demonstrated a variable improvement in fatigue rates (initial flow 826 +/- 265 ml/min; time to no forward flow, 2.5, 7.5, 7.5, 10, and 200 minutes). Four of six pouches that received the benefit of long-term electrical muscle conditioning and a vascular delay (N = 6) were able to generate flow for a 4 hour period, at which time the experiment was terminated (initial flow 478 +/- 204 ml/min; final flow 195 +/- 157 ml/min). After the 4 hour fatigue test was completed, one electrically conditioned pouch was placed in series with the heart and served as a counterpulsator. The initial volume of blood pumped by the muscle pouch was 262 ml/min or 13.8% of cardiac output. After the pouch had contracted at a rate of approximately 45 beats/min for 1 hour, the volume of blood pumped was 178 ml/min, or 11% of cardiac output. In three other animals a pouch was fashioned and then left in situ for a 1 to 3 week period before hydraulic testing. These pouches generated significant initial flows (390 +/- 60 ml/min), which demonstrates the feasibility of further study of permanent pouches. These results suggest that permanent electrical muscle conditioning and perhaps a vascular collateral delay might permit an auxiliary skeletal muscle-powered ventricle to assume a portion of left ventricular function.     

Right ventricular cardiomyoplasty: 10-year follow-up

BACKGROUND: Chronically depressed right ventricular (RV) function presents an unsolved therapeutic challenge in cardiac surgery. Despite recent advances in medical and surgical therapies, prognosis remains poor and patient's quality of life and mortality are frequently unacceptable. The aim of this study is to present the first clinical report and long-term results of RV dynamic cardiomyoplasty applied in patients with RV failure caused by isolated RV cardiomyopathies. METHODS: Seven consecutive patients (5 males, 2 females; mean age, 40 +/- 9 years; range, 15 to 63 years) from a series of 113 cardiomyoplasty procedures performed at Broussais and Pompidou Hospitals were evaluated. The mean duration of follow-up was 10 +/- 3.5 years. All patients had predominant RV dysfunction, associated with tricuspid regurgitation in 6 patients. The cause of RV failure was arrhythmogenic cardiomyopathy (4 patients), ischemic (2 patients), and Uhl's disease (1 patient), and endomyocardial fibrosis (1 patient). Six patients were in preoperative New York Heart Association functional class III and 1 was in intermittent class III/IV. The mean preoperative ejection fraction (measured by isotopic technique) was 18% +/- 5.7% for the right ventricle and 40% +/- 13% for the left ventricle. Right ventricular dynamic cardiomyoplasty consists of wrapping the RV free walls with the left latissimus dorsi muscle flap. The distal part of the latissimus dorsi muscle is fixed to the diaphragm and then electrostimulated. Six patients required associated tricuspid valve surgery. RESULTS: There were no perioperative deaths. The mean duration of follow-up was 10 +/- 3.5 years. Six patients are alive with a remarkable quality of life, 4 are in New York Heart Association functional class I and 2 are in class II. One patient who was in New York Heart Association functional class II died in postoperative year 7 caused by stroke. At last follow-up, mean RV ejection fraction was 33% +/- 11.8% and left ventricular ejection fraction was 52% +/- 12.6%. CONCLUSIONS: The results of this long-term study demonstrate hemodynamic and functional improvements after RV cardiomyoplasty without perioperative mortality, no long-term malignant arrhythmias, and RV dysfunction related deaths. We believe that RV cardiomyoplasty, associated with tricuspid valve surgery when required, could be an effective treatment for severe RV failure.     

Growth potential of latissimus dorsi muscle flaps used in the cardiomyoplasty procedure

Synchronously stimulated latissimus dorsi muscles have been used for cardiomyoplasty in adult patients with heart failure. This procedure has the potential of being used in pediatric patients to enlarge a hypoplastic ventricle or to reinforce the right atrium in the Fontan procedure. The growth potential of such a myograft was studied. Young piglets weighing 18 to 22 kg underwent right latissimus dorsi cardiomyoplasty while the latissimus dorsi weight and myoplasty area were measured. In half of the animals, the myograft was not stimulated and in the others it was continuously stimulated with an atrioventricular sequential pacemaker to contract in synchrony with the heart. Two months later, with doubling of body weight, the hearts were removed for study. In both groups, significant (p less than 0.05) increase in latissimus dorsi weight (+92% +/- 15% nonpaced versus +77% +/- 3% paced) and myoplasty area (+107% +/- 13% nonpaced versus +116% +/- 30% paced) were noted. The results in stimulated versus nonstimulated animals were not significantly different. Thus, not only does cardiomyoplasty offer a contractile tissue to repair or enlarge cardiac chambers, but this tissue can also grow in young patients and avoid subsequent size mismatch.     

Left ventricular cardiomyoplasty by the use of a free latissimus dorsi myograft with a vascular anastomosis--augmentation of regional cardiac performance in dyskinetic segments

This study was performed to evaluate the ability of a free revascularized Latissimus Dorsi (LD) graft placed on dyskinetic segments of the left ventricle to augment regional left ventricular performance in 8 adult dogs. LD muscles preconditioned for 30 days were revascularized with the internal mammary artery and right atrial appendage. The free graft was sutured on the ischemic area of the left ventricular anterolateral wall, produced by ligation of the left anterior descending coronary artery. Grafts were paced at a burst frequency of 25 and 50 Hz, at a synchronization ratio of 1:1, 2:1, and 3:1. Effects of synchronously paced LD grafts on regional myocardial performance and hemodynamics were evaluated by placing ultrasonic crystals on the ischemic area and hemodynamic parameters. The flow rate of revascularized thoracodorsal artery (TDA flow) was measured during synchronously pacing of the grafts. Systolic bulging was shown in the ischemic area without graft pacing: %shortening (%S) = -9.5 +/- 3.6%. Graft pacing at a burst frequency of 25 and 50 Hz resulted passive segmental shortening of the ischemic left ventricular myocardium: %S = +3.9 +/- 1.9% (p less than 0.01, vs values without pacing) and +5.5 +/- 1.9% (p less than 0.01, vs values without pacing), respectively. The left ventricular pressure increased from 74 +/- 14 mmHg to 83 +/- 15 mmHg (p less than 0.01) with graft pacing at a burst frequency of 50 Hz. The peak aortic flow also was augmented by an average of 30 +/- 6% at paced cardiac cycles. The pattern of TDA flow during 1:1 synchronous pacing was changed to be dominant in diastolic, unlike the pattern without graft pacing. Values of TDA flow rate, however, increased after the initiation of pacing and reached 270 +/- 38% of control values. In conclusions, this study shows that a revascularized free LD graft has an ability to contract in systole against the left ventricular wall stress, and to augment regional left ventricular performance in dyskinetic segments. And sufficient blood perfusion to the grafts can be maintained during synchronously pacing of the grafts in cardiac systole.     

Full-thickness dynamic cardiomyoplasty of the left ventricle with free revascularized latissimus dorsi myografts. An experimental feasibility study.

Dynamic cardiomyoplasty, with use of a free latissimus dorsi myograft revascularized by the internal thoracic artery and vein, was performed in eight dogs subjected to electrical preconditioning for 8 to 12 weeks (group I) and in six unconditioned dogs (group II). The procedure was performed after the resection of the anterior wall of the left ventricle. Cardiac output and left ventricular stroke work were augmented by 23.7% +/- 9.4% and 44.1% +/- 15.9% after graft pacing with 50 Hz burst stimulation at a 1:1 synchronization ratio, while left atrial pressure ranged from 8 to 12 mm Hg. Analysis of the left ventricular function curve showed that graft pacing at rates of 1:1, 2:1, and 3:1 augmented global left ventricular function. Hemodynamic benefit by continuous pacing at a 3:1 ratio was seen for 1.97 +/- 1.90 hours (0.5 to 6.1 hours) in group I until complications unrelated to the graft terminated the study, while it lasted for only 0.19 +/- 0.09 hour in group II. During the stimulation, the ratio of the lactate output to the oxygen consumption of the graft in group I, a possible indicator of metabolic shift, was significantly less than in group II, (0.46 +/- 0.58 and 6.34 +/- 1.73; p < 0.01). We conclude that free grafts of transformed latissimus dorsi muscle can augment global left ventricular performance, with a physiologic preload by oxidative metabolism, and provide a viable option in full-thickness dynamic cardiomyoplasty.     

Right ventricular dynamic cardiomyoplasty: an experimental model

The effectiveness of dynamic cardiomyoplasty as a means of haemodynamic support in heart failure remains controversial. We have undertaken a study of right ventricular dynamic cardiomyoplasty in sheep using intravenous propranolol to provoke heart failure. Muscle conditioning was performed with cardiomyostimulators following a previously established protocol. We performed multiple invasive measurements of haemodynamic parameters including arterial blood pressure, cardiac output, pulmonary artery capillary wedge pressure, right ventricular dp/dt and end diastolic pressures. These were performed before induction of heart failure, after induction of heart failure, and with pacing of the cardiomyoplasty flap in established heart failure. Our results confirm that we were able to establish significant heart failure and that subsequent pacing of the conditioned muscle flap was able to return cardiac output and right ventricular function to their pre-failure control levels.     

Activity–rest stimulation of latissimus dorsi for cardiomyoplasty: 1-year results in sheep

Background. In dynamic cardiomyoplasty electrostimulation achieves full transformation of the latissimus dorsi (LD); therefore, its slowness limits the systolic support. Daily activity–rest could maintain partial transformation of the LD.

Methods. Sheep LD were burst-stimulated either 10 or 24 hours/day. Before and 2, 4, 6, and 12 months after stimulation, LD power output, fatigue resistance, and tetanic fusion frequency were assessed. Latissimus dorsi were biopsied at 6 months, and sheep sacrificed at 12 months.

Results. After 1 year of 10 hours/day stimulation LD was substantially conserved and contained large amounts of fast type myosin. From 2 months to 1 year of stimulation the power per muscle of the daily rested LD was greater than that of the left ventricle, being three to four times higher than in the 24-hour/day stimulation.

Conclusions. If extended to humans, these results could be the rationale for the need of a cardiomyostimulator, whose discontinuous activity could offer to patients the long-standing advantage of a faster and powerful muscle contraction.     

Diabetes-induced alterations in latissimus dorsi muscle properties impair effectiveness of dynamic cardiomyoplasty in rats

Short-term diabetes was induced in male Wistar rats with streptozotocin injection. The effects of diabetes on latissimus dorsi (LD) muscle contractile and biochemical properties and acute cardiomyoplasty (CDM) were assessed and compared with data from 16 control rats. Isometric force, contractile properties, and fatigue were measured in electrically stimulated muscles (0.3 ms, 1-256 Hz), and Na+K+ and Ca2+ATPase activities were quantified in muscle membrane preparations. Systolic arterial pressure and aortic blood flow were recorded at rest and during LD muscle stimulation. Compared with control muscle, diabetic muscle showed smaller maximum specific tetanic tension and lower rates of rise and fall in force. Diabetic LD muscle also showed lower muscle enzyme activities. Twitch tension and fatigue did not differ between groups. Smaller increases in aortic flow and systolic pressure after CDM were found in diabetic rats compared to controls. The marked decrease in CDM effectiveness in diabetic rats likely reflected the alterations in muscle properties associated with diabetes.     

Vascular delay of the latissimus dorsi provides an early hemodynamic benefit in dynamic cardiomyoplasty.

OBJECTIVES: Dynamic cardiomyoplasty (CMP) as a surgical treatment for chronic heart failure improves functional class status for most patients. However, significant hemodynamic improvement with latissimus dorsi muscle (LDM) stimulation has not been consistent. The current protocols do not allow early LDM stimulation after CMP surgery. We hypothesized that vascular delay of LDM would increase myocardial assistance after CMP and allow early (48-h) LDM stimulation after CMP. METHODS: Mongrel dogs (n = 24) were divided in four groups: 1) controls (n = 6), single-stage CMP; 2) Group ES (n = 6), single-stage CMP with early LDM stimulation beginning 48 h, postoperatively; 3) Group VD (n = 6), vascular delay of the LDM followed by CMP without early LDM stimulation, and 4) Group VDES (n = 6), vascular delay of LDM (14-18 days), followed by CMP with early stimulation (48 h postoperatively). Two weeks after CMP, global cardiac dysfunction was induced by injecting microspheres into the left coronary artery. LDM-assisted (S) beats were compared with nonstimulated beats (NS) by measuring aortic pressure (AoP), LV pressure, aortic flow, and by calculating first derivative of LV contraction (+/-dP/dt), stroke volume (SV), and stroke work (SW). RESULTS: In ES, LDM stimulation had no effect on the hemodynamic parameters. In the other groups, LDM stimulation significantly (p < 0.05) increased AoP, LVP, dP/dt, SV, and SW. However, these increases were much larger in VD and VDES. In VD, LDM stimulation increased peak AoP by 21.5+/-3.8 mm Hg, LVP by 22.1+/-4.1 mm Hg, dP/dt by 512+/-163 mm Hg/sec, SV by 10.4+/-2.3 mL, and SW by 22.1+/-5.4 g/m(-1). Similarly, in VDES, LDM stimulation increased peak AoP by 24.1+/-4.7 mm Hg, LVP by 26.2+/-4.3 mm Hg, dP/dt by 619+/-47 mm Hg/sec, SV by 6.5+/-0.7 mL, and SW by 16.7+/-4.1 g/m(-1). CONCLUSIONS: In dogs with global LV dysfunction, CMP after vascular delay resulted in a significant improvement in hemodynamic function measured 2 weeks after surgery. This improvement was not provided by single-stage CMP with or without early stimulation. Vascular delay of the LDM before surgery may play an important role for early benefit after CMP, shorten the overall muscle training period, as well as increase hemodynamic response to LDM stimulation.     

Anatomic topographic study of the latissimus dorsi muscle of the spine in relation to cardiomyoplasty

The results of an anatomo-topographical study of the latissimus dorsi muscle in relation to surgery for cardiomyoplasty are discussed. The vascular anatomy of 25 flaps formed from the muscle were studied on the basis of the findings of angiography. The results allowed the conclusion that the latissimus dorsi muscle can be used as a transplant in operation for cardiomyoplasty.     

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.)     

Left ventricular systolic performance in failing heart improved acutely by left ventricular reshaping

OBJECTIVE: If the geometric distortion during dilated heart failure could be corrected, the tension on the myocytes would be decreased, thereby leading to an improvement in left ventricular systolic function. We tested the effects of the CardioClasp (CardioClasp Inc, Pine Brook, NJ), a left ventricular reshaping device, on the failing heart, and our empirical data were compared with computationally derived data. METHODS: Heart failure was induced by 4-week rapid cardiac pacing. At the terminal experiment, an isolated failing heart preparation (isovolumic contraction, n = 5) or an intact failing heart in vivo (n = 7) was used. The effects of the reshaping device on left ventricular performance were assessed by the slopes (Ees) of the left ventricular end-systolic pressure-volume relations, hemodynamics, and echocardiograph before and after placing the CardioClasp on the heart. The change in Ees as the result of left ventricular reshaping was also estimated from computed theoretical analysis and compared with empirical data. RESULTS: There was a significant change in left ventricular dimension after placing the CardioClasp on the heart. In isolated heart preparation, Ees significantly increased from 1.40 +/- 0.44 mm Hg/mL to 2.42 +/- 0.63 mm Hg/mL after placing the device on the heart but returned to the baseline level (1.46 +/- 0.27 mm Hg) after removing it. Left ventricular developed pressure and left ventricular fractional area shortening were significantly increased as the result of left ventricular reshaping. Ees derived from computed theoretical analysis was highly correlated with confirming empirical data. CONCLUSIONS: The CardioClasp can reshape the left ventricle and improve left ventricular systolic performance in failing hearts.