Combination of low-dose total skin electron beam therapy and subsequent localized skin electron beam therapy as a therapeutic option for advanced-stage mycosis fungoides.

Electron beam therapy (EBT) is an established treatment for mycosis fungoides (MF), but evidence for the use of EBT in advanced cutaneous conditions is limited, and optimal scheduling of the regimen for such conditions remains unclear. We report the case of a 44-year-old woman diagnosed with MF with widespread cutaneous lesions, including multiple huge tumours in the craniofacial area. Low-dose total skin (TS)EBT and subsequent localized skin (LS)EBT achieved striking improvements in eruptions. Oral etretinate was also administered during therapy. Our experience implies that combined TSEBT and LSEBT may be worth attempting when a patient presents with both widespread lesions and prominent tumours, even when the tumours are extremely large.

[Recurrent right atrium thrombus in long term follow-up after repair of atrial septal defect; report of a case].

A 76-year-old woman with recurrent ball-like thrombus in right atrium after primary repair of atrial septal defect (ASD) and tricuspid annuloplasty was successfully treated by surgical resection and strict management of anticoagulation and antiarrhythmics. A routine follow-up echocardiography, 27 months after initial operation, showed a swinging ball mass looks like a myxoma in the right atrium. Intra-operative findings showed the mass attached the free wall of right atrium with a 5 mm stalk, which was far from the ASD patch, initial suture lines, and the tricuspid annulus. Histological examination revealed the round and smooth mass was thrombus. She was successfully discharged 13 days after the 2nd operation without any complaint. A postoperative laboratory check demonstrated normal coagulability. Despite the patient was prescribed warfarin potassium and aspirin, the follow-up echocardiography at 3 months showed a recurrent thrombus in the right atrium. However the strict anticoagulation therapy with warfarin potassium and aspirin induced thrombolysis and prevent any embolic event, 1 month later. It is important to continue a strict anticoagulant therapy and prevent arrhythmia to avoid recurrence thrombus.

[Mitral valve replacement for mitral regurgitation caused by papillary muscle head rupture complicating acute myocardial infarction: report of a case].

A 71-year-old female was admitted for acute posterolateral infarction. On the next day of the successful emergency perctaneous coronary intervention, she developed severe dyspnea and was intubated at intensive care unit. Massive mitral regurgitation was detected on color Doppler imaging and left ventricular cardiac failure was increasingly developed. The urgent operation was performed for papillary muscle rupture 18 days after first episode. Head rupture of the posterior papillary muscle was found during surgery and the mitral valve was replaced by a prosthetic valve (SJM # 25). The postoperative course was uneventful and she discharged on 52 days after surgery.

Breast-conserving therapy for ductal carcinoma in situ.

This retrospective analysis evaluates the treatment results and prognostic factors of 114 patients with ductal carcinoma in situ (DCIS) undergoing breast conserving therapy (BCT) at Keio University Hospital Department of Radiology, between 1988 and 1997. A total of 132 patients with DCIS of the breast came to our hospital between 1988 and 1997, and 114 cases were suitable candidates for BCT. All of the patients were female and ranged in age from 26 to 81 years (median 46). Ninety-one patients were premenopausal, and 23 were postmenopausal. Median clinical tumor size was 2.0 cm (0-8.0 cm). Postoperatively 48 cases received 50 Gy/25 fractions of external irradiation to the whole breast via tangential ports. The follow-up period after treatment ranged from 11 to 162 months (median 46.7). The local relapse-free rate and overall survival rate of the 114 patients were 89.5% and 100%, respectively. Local failure and regional nodal failure occurred in 12 and 1 patient, respectively. Radiotherapy was a significant risk factor for local failure (p=0.05). No postmenopausal patients developed local failure, but the difference did not reach statistical significance (p=0.103). The 12 recurrent cases underwent additional surgery and all remain alive without recurrence, to date, i.e., at least 16 months. Breast-conserving surgery plus irradiation is appropriate treatment for DCIS patients.

Histological remodeling in an ovine heart failure model resembles human ischemic cardiomyopathy.

Staged coronary embolization, causing myocardial microinfarctions, has been shown in dogs and sheep to cause chronic ischemic heart failure (HF) that resembles the hemodynamics of the human condition. However, its histopathological basis remains unclear. We examined the hypothesis that the ventricular remodeling seen in such sheep resembles the histopathology of human ischemic cardiomyopathy (ICM). Understanding the pathophysiology of this model will determine its place in the development of treatment strategies for HF. Global left ventricular (LV) damage resulting in HF was induced by staged coronary embolization in 11 sheep. Six others served as controls (normal control, NC). In HF sheep, the heart was harvested 6 months after LV ejection fraction (EF) had stabilized at <35%. Histopathological profiles were compared in biventricular transverse sections at midpapillary level using computed image analysis. LV end-diastolic volume increased in the HF group from 84.9+/-29 to 122.4+/-30.3 ml (n=11, P<.05), but myocytes across the LV wall in noninfarcted zones decreased (435.7+/-38.2 NC; 297.8+/-48.4/unit area HF; n=11, P<.0001) as did myocyte nuclear density (990.5+/-51.5 NC; 677.5+/-121.1/mm(2) HF, n=11, P<.0001). In contrast, LV replacement and interstitial fibrosis increased as did myocyte diameter in noninfarcted zones: 0.1+/-0.1 to 6.2+/-4.5% (P=.0049); 2.0+/-1.0 to 7.6+/-4.9% (P=.0149); and 10.0+/-0.5 to 15.9+/-2.2 microm (P<.0001), respectively. Although LV myocyte nuclear length increased (10.2+/-1.0 NC; 12.2+/-0.9 microm HF, n=11, P=.0006), right ventricular (RV) myocyte nuclear density and length did not alter. In this ovine chronic HF model, LV dilation and interstitial and myocyte remodeling resemble human ICM.

Effect of combined treatment with radiation and low dose etoposide on cell survival.

BACKGROUND: To improve the radiotherapy results, we evaluated etoposide as an effective radiosensitizer by using cultured cell-lines. MATERIALS AND METHODS: Four cell lines having different doubling times (DT) were used: V79 (Chinese hamster fibroblasts, DT = 9 hours), (1), T24 (human bladder cancer, DT = 19 hours) (2), MDA-MB231 (human breast cancer, DT = 25-30 hours) (3) and RMG1 (human ovarian cancer, DT = 50 hours) (4). Cell survival was determined by colony assay and cell cycle analysis was performed by flow-cytometry. RESULTS: The survival curves showed RMG1 to be the most radiosensitive, followed by MDA-MB231, T24, and V79. V79 was most chemosensitive to etoposide, followed by T24, MDA-MB231 and RMG1. Neither 24-hours exposure to etoposide (< or = 0.05 microgram/ml) or 0.5-h exposure (< or = 1.0 microgram/ml) had any cell killing effect on any of the cell lines used. When the cells were irradiated after exposure to 1 microgram/ml of etoposide for 0.5 hours, no radiosensitization was observed in any of the cell lines except V79. Enhanced radiosensitivity was observed in V79 and T24 cells (which have a relatively short DT) when they were incubated with 0.05 microgram/ml etoposide for 24 hours but no enhanced effect was seen in MDA-MB231 or RMG1 cells (which have a relatively long DT). CONCLUSION: It is suggested that a combination of radiation and etoposide may be useful in the treatment of rapidly growing cancer.

Cell killing and mutation induction by heavy ion beams.

Carbon beam radiotherapy for cancer patients was initiated in Japan in June 1994. This study attempts to clarify the radiobiological effects of heavy ion beams. In this study, human cancer cell lines (RMG-1, MDA-MB231) and V79 cells were used. The cell killing was determined by colony forming assay, and mutation induction was determined by counting the number of 6-thioguanine resistant colonies (hprt locus mutation assay). The cell lines were irradiated with carbon (20 or 80 keV/microm) or neon beams (80 keV/microm). Carbon ions with a higher LET value (80 keV/microm) had an enhanced cytotoxic effect compared to those with a lower LET value (20 keV/microm). Carbon beams produced a slightly stronger cytotoxic effect than neon beams when irradiated at the same LET level (80 keV/microm), but the difference was not remarkable. The mutant fraction was significantly higher in all cell lines when they were irradiated with heavy ion beams, compared to the results for X-ray irradiation. The mutant fraction increased when the LET of the carbon beams increased. At equivalent LET values, the mutant fraction was lower for neon beams than for carbon beams. Fractionation of carbon beam irradiation had no effect on survival, but reduced the mutant fraction. Neon beams might be more appropriate for heavy ion therapy, especially when higher doses are being used. In addition, the fractionation of heavy ion beam administration might be appropriate for reducing the mutant fraction.

Clinical results of implantation of an endovascular covered stent-graft via midsternotomy for distal aortic arch aneurysm.

UNLABELLED: We have been implanting endovascular stent grafts (EVG) via midsternotomy for distal aortic arch surgery since February 1997. The early clinical results are evaluated. METHODS: There were 11 true aneurysms (8 fusiform, 3 saccular) and one chronic type B dissection. The average age was 68 yr (63-81). EVGs were PTFE-covered two-8 bend Z stents in the first eight cases and made with the same stents and ultrathin woven Dacron grafts in the last four cases. RESULTS: Total arch replacement and aortocoronary bypass grafting were combined in one and two patients, respectively. The average retrograde cerebral perfusion time was 42+/-8 min. The cardiopulmonary bypass time averaged 211+/-26 min. All patients awoke early after operation (4.5+/-1.2 h). All but one case was extubated within 24h. There was no operative mortality, but paraplegia and cerebral infarction were complicated in one case each. Their maximum diameter (73.9+/-21.2mm) decreased significantly after operation (68.7+/-20.1mm) and one year thereafter (63.1+/-16.0 mm). True aneurysms were thrombosed completely. A chronic type B dissection revealed impending rupture due to false lumen infection one year after operation. The whole descending aorta replacement was performed but the patient died 6 months thereafter due to cerebro-vascular complication. CONCLUSION: Implantation of EVGs reduces operative invasion for distal arch surgery. This procedure should improve mortality, while long-term results have not been clarified.

Indications of stereotactic irradiation for brain lesions.

Stereotactic radiosurgery (SRS: single-fraction stereotactic irradiation) was originally developed to treat benign lesions in the brain, and has been adopted for the treatment of small primary or metastatic brain tumours. It has recently been recommended that stereotactic radiotherapy (SRT: fractionated stereotactic irradiation) be applied to the treatment of brain tumours; however, it requires much more time and work than SRS, and sufficient radiobiological evaluations of these techniques have never been carried out. Biologically effective doses were calculated to determine the indications for SRS and SRT, and to decide on an effective SRT schedule, incorporating the factors of 'repair' and 'cell proliferation'. The results suggest that SRS would be recommended for arteriovenous malformations and benign tumours that have distinct margins separating them from surrounding normal tissue and SRT would be recommended for benign or malignant brain tumours without clearly defined boundaries. The recommended SRT schedules would be 7 Gy x 7 fractions every other day for malignant tumours and 3.5 Gy x 12 fractions every other day for benign tumours. However, clinically, these schedules should be modified according to many other factors in individual cases.

The modified tangential irradiation technique for breast cancer: how to cover the entire axillary region.

PURPOSE: The two-portal tangential irradiation technique has usually been applied to breast cancer patients after breast-conserving surgery (1, 2) and is expected to irradiate the axillary lymph node region to some extent (3). We investigated the range of the axillary region covered by this technique and tried to devise an optimal irradiation technique (modified tangential irradiation) that would cover the axillary lymph node region properly. METHODS AND MATERIALS: We checked the status of the surgical clips left at axillary lymph node sites by reviewing the simulator films and planning CT scans of 63 patients who underwent axillary dissection of level I, I-II, or I-III lymph nodes. Then we created the modified tangential irradiation technique and applied this technique to 16 patients and checked the irradiation volume by CT scans. RESULTS: We found that all of the surgical clips on lateral-view simulator films were on the ventral side of the dorsal edge line of the humeral head. All but one clip were on the caudal side of the caudal edge line of the humeral head. Accordingly, it is possible to irradiate almost all axillary lymph node regions by setting the dorsal edge of the irradiation field on lateral-view simulator films at the dorsal edge of the humeral head and the cranial edge at the caudal edge of the humeral head. CONCLUSIONS: All breast tissue and the entire axillary lymph node region can be covered by the modified tangential irradiation technique without increasing the lung volume irradiated.

Ventricular remodeling after cardiomyoplasty in heart failure sheep: passive and dynamic effects.

BACKGROUND: Recent reports claim that cardiomyoplasty (CMP) has a girdling effect on the left ventricle, to prevent dilatation and functional deterioration, but the mechanism of its long-term effects on the native heart is not known. We compared the relative role of CMP's active squeezing and passive girdling in chronically failing hearts. METHODS: After induction of stable heart failure (left ventricular ejection fraction = 27% +/- 7%) by staged coronary microembolization, CMP was performed in 11 of 18 sheep. After 8 weeks pacing training of the latissimus dorsi muscle (LDM), cardiac assist was begun with 1:2 synchronous bursts in 6 sheep (d-CMP, n = 6), and the LDM in the passive group (p-CMP, n = 5) remained unstimulated. Four (base line) and 30 weeks after induction of heart failure, the pressure-volume relationship was derived. RESULTS: After 30 weeks in d-CMP the slope (Emax) of the end-systolic pressure-volume relationship increased by 66% +/- 55% (p < 0.05) and external work efficiency by 48% +/- 41% (p < 0.01). In the passive CMP and control groups, slope and external work efficiency were unchanged. Conversely, left ventricular end-diastolic volume decreased (-14% +/- 12%, p < 0.05) in the dynamic CMP group compared with a static course in the passive CMP group (3% +/- 10%, p > 0.05) and an increase (18% +/- 15%, p < 0.05) in controls. CONCLUSIONS: Dynamic CMP improved native heart's contractility and external work efficiency. In addition, whereas passive CMP has simply a girdling effect, dynamic CMP also induces reverse left ventricular chamber remodeling.

Sarpogrelate reduces mechanical hemolysis in patients with heart valve prostheses.

OBJECTIVE: We evaluate the clinical efficacy of sarpogrelate, an antiplatelet drug that improves red blood cell deformability, to reduce the intravascular hemolysis problems suffered frequently by patients implanted with heart valve prostheses. SUBJECTS: Subjects were 34 patients undergoing mechanical heart valve replacement and having serum lactate dehydrogenase concentrations 20% above the maximum normal range. METHOD: Sarpogrelate was given daily, 100 mg orally for the first 6 months and 200 mg thereafter. RESULTS: Average serum lactate dehydrogenase decreased significantly from 423 +/- 108 IU/l, to 391 +/- 83 IU/l with the 100 mg dose, and to 361 +/- 86 IU/l with the 200 mg dose. The percentage of reticulocytes decreased from 15.5 +/- 5.3/1000 to 15.3 +/- 5.7/1000 at the 100 mg dose and 13.1 +/- 4.0/1000 at the 200 mg dose. Serum iron concentrations increased significantly from 63.2 +/- 24.8 micrograms/dl to 76.2 +/- 16.2 micrograms/dl at the 100 mg dose, and to 70.9 +/- 26.2 micrograms/dl with the 200 mg dose. CONCLUSION: Sarpogrelate is a useful drug for patients with implanted heart valve prostheses and subsequent high serum lactate dehydrogenase because it works as an antiplatelet drug and reduces mechanical hemolysis.

Novel method to estimate ventricular contractility using intraventricular pulse wave velocity.

We developed a novel technique for estimating ventricular contractility using intraventricular pulse wave velocity (PWV). In eight isolated, cross-circulated canine hearts, we used a fast servo pump to inject a volume pulse into the base of the left ventricular chamber at late diastole and at late systole. We measured the transit time of the volume pulse wave as it traversed the distance from base to apex and calculated the intraventricular PWV. The intraventricular PWV increased from diastole (2.3 +/- 0.4 m/s) to systole (11.7 +/- 2.4 m/s, P < 0.0001 vs. diastole). The square of the intraventricular PWV at late systole correlated linearly with the left ventricular end-systolic elastance (r = 0.939, P < 0.0001) and with the end-systolic Young's modulus (r = 0.901, P < 0.0001). Moreover, the intraventricular PWV was insensitive to preload. We conclude that the intraventricular PWV at late systole reflects left ventricular end-systolic elastance reasonably well. The fact that estimation of PWV does not require volume measurement or load manipulation makes this technique an attractive means of assessing ventricular contractility.

[Hard-copy (film) versus soft-copy (CRT) reading performance between compressed and uncompressed images: SOLs in abdominal CT images].

The objective of this study was to examine the feasibility of soft-copy (CRT) reading and suitable compression. Forty abdominal CT images with a space-occupying lesion (SOL) in liver and 40 normal images were selected for receiver-operating-curve (ROC) analysis. Each image was compressed by JPEG extended mode into 1/10 its original capacity, and then an expanded image was printed on film. Ten radiologists evaluated the presence of liver SOLs (primary and secondary tumors) on soft-copy (CRT) and hard-copy (film) images. Each radiologist reviewed four types of images (original and compressed hard-copy and original and compressed soft-copy images). Values of the area under the curve in the various ROC analyses were 0.858 (FILM) and 0.842 (CRT) for original images and 0.879 (FILM) and 0.846 (CRT) for compressed images. The results of ROC analysis showed better reading performance with hard-copy than soft-copy images, but the difference was not statistically significant. Compressed images showed a higher value (0.879) than original images (0.858), a difference that was statistically significant (p < 0.029) by the paired t-test but not by the jackknife method. The results indicate that soft-copy reading is a clinically acceptable alternative to hard-copy reading. We have had no difficulty in reading abdominal CT images compressed to 1/10 of the original size by the JPEG method. This study was supported in part by a grant from the Japanese Ministry of Health and Welfare.

Late retinal complications of radiation therapy for nasal and paranasal malignancies: relationship between irradiated-dose area and severity.

PURPOSE: Radiation-induced cataract, once a notorious ocular complication of radiation therapy, is no longer considered a severe complication, because visual acuity can be restored by surgical treatment without significant complications. Late retinal complications of retinopathy and glaucoma, for which there is no effective method of treatment, have become serious complications of radiotherapy of the head and neck. We retrospectively investigated the risk of late retinal complications of radiotherapy for nasal and paranasal malignancies according to the radiation dose and area of the retina irradiated. METHODS AND MATERIALS: Between October 1982 and May 1996, 43 eyes of 25 patients were exposed to fractionated external-beam irradiation for treatment of advanced nasal and paranasal cancer. None of the patients had tumor invasion into the eyes. The patients were followed ophthalmologically for a minimum of 2 years (range 2.0-11, mean 4.5, median 3.3). The radiation dose and area of the retina irradiated were estimated from the dose distribution figures calculated using the portal films and CT scan. RESULTS: Major late adverse effects of radiotherapy were observed in the retina in 9 of 43 eyes (in 8/25 patients). Radiation retinopathy was observed in 7 eyes, and the cumulative incidence was 25%. The median interval before the onset of symptoms attributable to retinopathy was 32 months (range 16-60). Neovascular glaucoma developed in 3 of the 43 eyes, with a cumulative incidence of 7%. The median period to the onset of symptoms attributable to glaucoma was 22 months (range 16-26). Obstruction of the central retinal artery was observed in 1 eye. The irradiation doses to the retinas that developed late complications ranged between 54-75 Gy (mean 61, median 61). No patients who received less than 50 Gy developed retinal complications. The retina in 21 eyes was exposed to a dose of 50 Gy or more. In 13 of the 21 eyes, 60% or more of the retina was irradiated, and 8 of the eyes (62%) in this group (> or = 50 Gy, > or = 60%) developed severe retinal complications, whereas such complications only developed in 1 of the 8 eyes (13%) in the other group (> or = 50 Gy, > or = 60%). The results suggest that the radiation dose and area irradiated are the most important factors in the development of severe complications. CONCLUSION: Radiation-induced retinopathy and glaucoma are more serious late complications than cataracts, which are easily treated with surgery. We investigated the risk of late retinal complications of radiotherapy, and our findings suggested that the radiation dose and area irradiated are the most important factors in the development of severe complications. We recommend that the radiation dose and area of the retina irradiated be minimized in patients at risk of eye complications, and the patients should be closely followed by periodic ophthalmologic testing after treatment.

Ventriculoarterial coupling with intra-aortic balloon pump in acute ischemic heart failure.

PURPOSE: We analyzed the mechanism of effects of intra-aortic balloon pumping using the pressure-volume relationship and ventriculoarterial coupling in the normal and failing hearts. MATERIALS: In 12 anesthetized Holstein calves (weight, 94 +/- 8 kg), the ventricular end-systolic and arterial elastances, pressure-volume area, and external work were analyzed during steady-state contractions with traditional hemodynamic parameters with intra-aortic balloon pumping-off and -on (1:1 synchronous ratio). An acute ischemic heart failure was induced by injecting 10 microm microspheres (4.2 +/- 1.8 x 10(7). 100g left ventricular weight-1) into the left main coronary artery; all measurements were repeated. RESULTS: Intra-aortic balloon pumping did not change hemodynamic parameters in the control. However, during heart failure, intra-aortic balloon pumping decreased the arterial elastance from 3.6 +/- 1.3 mm Hg to 2.9 +/- 1.2 mm Hg. mL-1 while not affecting the ventricular end-systolic elastance, this resulted in an improvement of the ventriculoarterial coupling ratio from 3.1 +/- 0.8 to 2.3 +/- 0.8. Intra-aortic balloon pumping decreased not only end-systolic pressure (from 69 +/- 16 mm Hg to 64 +/- 19 mm Hg) but end-diastolic volume and pressure (from 139 +/- 38 mL to 137 +/- 37 mL and from 13. 9 mm Hg to 12.8 mm Hg, respectively) with the leftward shift of the pressure-volume loop. Pressure-volume area decreased (from 914 +/- 284 mm Hg to 849 +/- 278 mm Hg. mL) although stroke volume increased (from 21 +/- 6 mL to 24 +/- 6 mL). CONCLUSION: Reduction of the arterial elastance with intra-aortic balloon pumping improved the ventriculoarterial coupling ratio and increased stroke volume. Leftward shift of the pressure-volume loop resulted in the reduction of pressure-volume area, which suggests the conservation of the myocardial oxygen consumption.

In situ measurements of skeletal muscle power output using new capacitive strain gauge.

Experiments are described in which a fatigue index is determined for the latissimus dorsi muscle of sheep in situ, using capacitive strain gauges. Parallel experiments for invasive and non-invasive measurements are conducted, measuring global contraction and relaxation rates and shortening duration for paced muscle. The results show that, above one pulse per burst (5 V, 100 microseconds pulsewidth), contraction rates (62 +/- 11 mm s-1) and relaxation rates (50 +/- 7 mm s-1) are constant for unloaded muscle. For one animal, fatigue testing with a 2.5 kg load at six pulses per burst shows shortening rates increasing to a maximum (80 mm s-1) after 30 s and reducing to 5 mm s-1 after 150 s. The decrease in shortening amplitude is used as a fatigue index, log displacement against time. Power output is load dependent, measuring 4.7 W kg-1 with a 2.5 kg load. There is good agreement between the invasive and non-invasive measurements, thus providing a method for monitoring changes in muscle parameters non-invasively during future pacing transformation.

Development of a servo-controller of heart rate using a cycle ergometer.

In exercise training, precise control of exercise intensity would maximize the training efficacy while minimizing risks. To adjust work rate, heart rate (HR) has been used as a measure of exercise intensity. Thus, we developed a servo-controller of HR using a cycle ergometer. After estimating the transfer function from work rate to HR, we optimized feedback parameters for achieving a quick and stable HR response by means of a computer simulation. We then examined the performance of the servo-controller of HR in 55 healthy volunteers. We set the target HR at 60% and 75% of the age-predicted maximum HR. Times required for HR to reach 90% of the target HR were 136 +/- 33 and 137 +/-22s in the respective protocols. Standard deviations of the steady-state difference between the target and measured HRs were 2.5 +/- 0.6 and 3.8 +/- 1.1 beats/min. We conclude that the developed servo-controller makes it possible to precisely regulate HR and, thereby, exercise intensity.

Estimation of bacterial contamination in ultrapure water: application of the anti-DNA antibody.

We constructed and established a hybridoma cell line that produces immunoglobulin G-type anti-DNA antibody. By using this antibody, we could successfully detect a single bacterial cell in ultrapure water (UPW). The detection system is composed of a membrane-supported western blotting-type immunoassay and a two-dimensional photon analyzer with high resolution. It can detect and count every bacterial cell in a wide field of view on a trapping filter i.e., a circle with an 18-mm diameter. This means 10 fg (10(-14) g) of bacterial DNA can be detected in the field. This system could be a useful tool for evaluating the number of bacteria contained by UPW and water used for medical purposes.

Improved efficiency of energy transfer to external work in chronic cardiomyoplasty based on the pressure-volume relationship.

OBJECTIVE: Cardiomyoplasty is a surgical procedure to support the failing heart, in which a burst-stimulated latissimus dorsi muscle flap is transposed and wrapped around the ventricles. The effect of dynamic cardiac compression, implemented as cardiomyoplasty, on left ventricular performance remains controversial; the mechanism by which clinical symptoms are improved remains unclear. To investigate the mechanism for improvement of patients' symptoms, it is important to evaluate the effects of cardiomyoplasty on left ventricular energetics and on left ventricular systolic and diastolic function. We therefore evaluated the efficiency of energy transfer from the native pressure-volume area to external work under conditions of 1:3 skeletal muscle burst pacing in an animal model with chronic heart failure. METHODS: In seven Merino-Wether sheep, cardiomyoplasty was performed after stable heart failure was induced by staged coronary embolizations (ejection fraction < 35%). Hemodynamic assessment including the assessment of the pressure-volume relationship was performed 8 weeks after cardiomyoplasty when the latissimus dorsi muscle was fully trained. Instantaneous left ventricular pressure and volume were measured with a catheter-tipped manometer and a conductance catheter during steady-state conditions and after a transient inferior vena cava occlusion. The effect of dynamic cardiac compression on left ventricular systolic function was assessed by comparing pre-assisted and assisted beats and on diastolic function by comparing assisted and post-assisted beats. RESULT: The slope of the end-systolic pressure-volume relationship decreased by 30.5% +/- 27.8% (p = 0.02) during assisted beats. However, left ventricular pump performance improved by increasing stroke volume and external work by 35.9% +/- 36.0% (p = 0.03) and 9.7% +/- 6.8% (p = 0.03), respectively, resulting in a reduction of the volume intercept. As a result, the end-systolic pressure-volume relationship shifted to the left. The efficiency of energy transfer from the native pressure-volume area to the overall external work improved by 7.6% +/- 8.2% (p = 0.04). Cardiomyoplasty did not affect the time constant of left ventricular isovolumic pressure decline or the maximal rate of pressure decay, which suggested that cardiomyoplasty did not affect left ventricular relaxation. CONCLUSIONS: Dynamic cardiac compression in the form of cardiomyoplasty enhanced left ventricular pump performance without interrupting left ventricular filling. The ratio of energy transfer from the native pressure-volume area to the overall external work suggests a myocardial oxygen-sparing effect of cardiomyoplasty.