Early and Late Effects of Passive Epicardial Constraint on Left Ventricular Geometry: Ellipsoidal Re-shaping Confirmed by Electron-beam Computed Tomography

doi:10.1016/j.healun.2005.02.025

The Journal of Heart and Lung Transplantation

Volume 25, Issue 1, January 2006, Pages 90-98

https://doi.org/10.1016/j.healun.2005.02.025 Get rights and content

Background

Previous studies have shown that passive epicardial constraint using a cardiac support device (CSD) reduces left ventricular (LV) size. However, specific data describing LV shape and the time course of changes in LV geometry are still incomplete. Thus, the aim of this study was—using 3-dimensional data sets obtained by computed tomography (CT)—to test the hypothesis that the CSD not only alters LV size but also LV shape, and that short-term post-operative changes in LV geometry are maintained during long-term follow-up.

Methods

Ten patients with non-ischemic dilated cardiomyopathy underwent electron-beam CT examination before and again at 2.6 ± 0.5 and 32.4 ± 8.7 months after CSD implantation. At end-diastole and end-systole LV volumes, the length-to-width diameter ratio and a sphericity index were determined and ejection fraction and end-systolic meridional and circumferential wall stress were calculated.

Results

Implantation of the CSD led to a significant reduction in LV size, a more ellipsoidal LV shape and a subsequent decrease of LV wall stress post-operatively (p < 0.05 for each), but no substantial changes were found between short- and long-term follow-up (p > 0.05 each). Mean pre-operative and early and late post-operative end-diastolic values were 310.4 ± 87.8, 235.5 ± 102.0 and 229.4 ± 103.1 ml for volume; 1.27 ± 0.20, 1.37 ± 0.20 and 1.38 ± 0.20 for diameter ratio; and 0.78 ± 0.22, 0.67 ± 0.26 and 0.65 ± 0.23 for sphericity index. A similar pattern was observed for end-systolic values. Ejection fraction was 23.4 ± 6.2%, 32.9 ± 11.6% and 34.4 ± 14.9%. End-systolic meridional and circumferential wall stress was 182.2 ± 45.6, 128.2 ± 52.6, 130.6 ± 56.7 kdyn/cm² and 411.5 ± 94.0, 297.4 ± 108.4 and 302.8 ± 117.5 kdyn/cm², respectively.

Conclusions

Three-dimensional data obtained by CT demonstrate that passive cardiac constraint leads not only to a size reduction but also to an ellipsoidal re-shaping. Our data indicate that these effects are primarily a short-term consequence of the CSD implantation but are maintained during long-term follow-up.

Section snippets

Study Population

In the context of a prospective clinical trial at our institution the CSD was implanted with or without additional cardiac surgery (mainly concomitant mitral valve repair) in a total of 36 patients. The present study consists of a sub-set of 10 patients who received only the CSD without additional surgery and were eligible for an electron-beam computed tomography (CT) examination pre- and post-operatively (i.e., had no contraindication to intravenous application of iodinated contrast material).

Results

All patients enrolled in this study recovered well from surgery, had no intra-operative complications, and tolerated the implanted mesh-graft well without early or late episodes of device-related heart failure. At first follow-up after device implantation patients’ symptomatology was improved significantly by 1 NYHA class for all individuals (p = 0.002) and was almost stable at second follow-up (p > 0.05): mean NYHA class was 2.7 ± 0.5 pre-operatively, 1.7 ± 0.5 early post-operatively and 1.5 ±

Discussion

There are several important findings from our study. First, passive epicardial constraint results not only in a reduction of ventricular size but also in a more ellipsoidal ventricular shape. Second, post-operative ventricular re-shaping appears to be a prompt effect of passive epicardial constraint rather than a gradually progressive process. Finally, early ventricular re-shaping is maintained during long-term follow-up and late ventricular re-dilation seems to be effectively prevented by

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In addition to fabric stiffness, the orientation of the primary and secondary fabric fiber groups, relative to the fabric and to the heart, is important. For instance, orientation of the Acorn CSD so that it is stiffest in the circumferential direction may counteract spherical remodeling [20]. As noted above, the effect of fabric fiber rotation in our study is interesting because the myofiber stress reductions are significantly greater without a different effect on compliance and pump function than in the baseline Acorn case.
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Reverse remodeling has been shown in several studies as well [21, 22]. In fact, cardiac restraint therapy not only leads to a size reduction but also restores the ellipsoidal geometry of the ventricles [23]. Despite the promising preliminary data, concerns remain regarding the technical details and related complications of CSDs [24].
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: Supported in part by Acorn Cardiovascular, Inc., St. Paul, MN.

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Failing heart—surgical aspectsEarly and Late Effects of Passive Epicardial Constraint on Left Ventricular Geometry: Ellipsoidal Re-shaping Confirmed by Electron-beam Computed Tomography

Background

Methods

Results

Conclusions

Section snippets

Study Population

Results

Discussion

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Failing heart—surgical aspects
Early and Late Effects of Passive Epicardial Constraint on Left Ventricular Geometry: Ellipsoidal Re-shaping Confirmed by Electron-beam Computed Tomography