Changes in right ventricular dimensions and performance after passive cardiac containment

Right ventricular dysfunction following continuous flow left ventricular assist device placement in 51 patients: predicators and outcomes

BACKGROUND

Right ventricular (RV) dysfunction following implantation of a left ventricular assist device (LVAD) is a serious condition and is associated with increased mortality.

METHODS

The aim of the study is to investigate the significance of pre-existing RV dysfunction, tricuspid valve (TV) insufficiency, and the severity of septal deviation following LVAD implantation on RV dysfunction, as well as the outcome and short-term complications in 51 patients from June 2006 to August 2010. Student t test was used to compare the data and estimate the p value.

RESULTS

Mean age was 55.1 ± 13, with a male to female ratio of 3.25. The 30-day mortality was 13.7% (7/51 patients), and the overall mortality was 23.5% (12/51 patients). Meanwhile, 21 patients (21/51; 41.2%) have undergone orthotopic heart transplantation. The mean time of support was 314.5±235 days with a median of 240 days at the time of closing this study. Echocardiographic evaluation of RV function pre- and post-implantation of an LVAD demonstrated septal deviation towards the left ventricle in immediate postoperative phase, which correlated with acute RV dysfunction (p = 0.002). Preoperative RV dysfunction was a significant predictor of postoperative right heart dysfunction following implantation of an LVAD (p = 0.001).

CONCLUSION

Preoperative RV dysfunction is a predictor of RV failure in LVAD patients. The adjustment of septal deviation through gradual increase of the LVAD flow can prevent the acute RV dysfunction following LVAD placement.

Cardiac support devices

Heart failure is an increasingly common condition in the United States and is associated with high mortality and burden to health care. It is a chronic condition that is characterized by progressive left ventricular enlargement. While medical therapy can slow the progression of left ventricular remodeling, surgical approaches to treatment have been developed to improve the survival and quality of life of heart failure patients. This article reviews the surgical procedures for left ventricular dysfunction and focuses on cardiac support devices as a new therapy for heart failure patients. The nursing care of patients with cardiac support devices will be presented and a case study will highlight practical points to help guide patient care.

No Additive Effect of Passive Containment Surgery in Patients With Aortic Regurgitation and Left Ventricular Dilation

BACKGROUND

After valve replacement in patients with aortic regurgitation short-term and long-term improvement of left ventricular function are related to early reduction of left ventricular dilatation. This case-control study was conducted to investigate the potential beneficial effects by concomitant application of the Acorn Cor Cap Cardiac Support Device (Acorn Cardiovascular Inc, St. Paul, MN) on reduction of ventricular dilatation in patients with aortic regurgitation and advanced ventricular dilatation undergoing aortic valve replacement.

METHODS

Of ten patients with longstanding aortic regurgitation and ventricular dilatation subjected to aortic valve replacement using mechanical valve prostheses, five were in addition subjected to application of the Cardiac Support Device (Acorn). Cardiac function and dimensions were measured by echocardiography preoperatively and 3 and 12 months postoperatively.

RESULTS

After aortic valve replacement, there was a rapid and sustained decrease in end-diastolic and end-systolic diameters (before operation 72 +/- 4 and 54 +/- 8 mm, to 54 +/- 10 and 40 + 11 mm at 3 months; and 53 +/- 9 and 35 +/- 6 mm, 12 months after operation). This did not differ after Cardiac Support Device (Acorn) application (before operation 74 +/- 1 and 56 +/- 5 mm; 52 +/- 8 and 39 +/- 9 mm, 3 months after operation; and 54 +/- 6 and 39 +/- 8 mm, at 12 months). The left ventricular ejection fraction remained unchanged in both groups.

CONCLUSIONS

Application of the Acorn Cor Cap Cardiac Support Device in patients with aortic regurgitation and severe ventricular dilatation does not influence reverse remodeling or cardiac function compared with aortic valve replacement alone.

Ventricular Volumes in Ebstein’s Anomaly: X-Ray Multislice Computed Tomography Before and After Repair

BACKGROUND

This study was performed to measure right and left ventricular volumes in Ebstein's anomaly before and after operation.

METHODS

Twenty-six consecutive patients were operated on with tricuspid valve repair and plication of the atrialized right ventricle, associated with a bidirectional cavopulmonary shunt in 15 patients. Right ventricular (RV) and left ventricular end-diastolic and end-systolic volume indexes were measured by x-ray computerized tomography before and after surgical repair. Left ventricular stroke index and ejection fraction were calculated.

RESULTS

Before surgery, the mean stroke index of the atrialized RV was 36 +/- 33 mL/m2, with severe reduction in 9 patients and aneurysmal aspect in 2 patients. After surgery, the atrialized RV was no longer identifiable. Both RV end-diastolic volume index and stroke index of the remaining effective RV were reduced. Bidirectional cavopulmonary shunt was a determinant factor of decrease in the effective RV end-diastolic volume index after repair. Conversely, left ventricular ejection fraction and stroke index increased significantly after surgery.

CONCLUSIONS

The atrialized RV with dyskinesia seems a good indication for a plication. RV end-diastolic volume index of the effective RV decreased after surgery. In severe cases, bidirectional cavopulmonary shunt was useful by decreasing RV end-diastolic volume, thus preventing further RV dilation. In all cases left ventricular ejection fraction and stroke volume index increased after surgery.

Internal defibrillation with minimal skeletal muscle activation: A new paradigm toward painless defibrillation

BACKGROUND

Shock-induced pain produces substantial morbidity in recipients of implantable cardioverter-defibrillators (ICDs). This pain likely derives from activation of skeletal muscle and associated nerves in the chest and abdomen. In an effort to develop a painless defibrillation system, we designed an electrode arrangement that incorporates a conductive sock placed around the heart to confine the electric shock field to cardiac tissue.

OBJECTIVES

The purpose of this study was to test whether cardiac defibrillation could be achieved without skeletal muscle activation using a novel electrode system.

METHODS

Eight adult mongrel dogs were studied. Force of skeletal muscle contraction was measured by strain gauges attached to the forelimbs during delivery of internal shocks ranging in energy from 0.1 to 31 J. Biphasic shocks were delivered (1) between a right ventricular coil and a subcutaneous dummy can (standard configuration), and (2) between a left ventricular coil and an epicardial electrode sock. Internal and external defibrillation thresholds (DFTs) were determined for each electrode configuration.

RESULTS

Shock-induced muscle contraction force was significantly lower using the sock electrode than with standard ICD electrodes at every shock energy level tested (P < .0001). Internal DFT was similar between electrode configurations (sock electrode: 8.6 +/- 4.2 J; standard: 11.0 +/- 6.3 J, P = .4), but muscle contraction force at DFT was greatly reduced with the new electrode system (1.8 +/- 2.0 kg vs 10.6 +/- 2.1 kg, P < .0001). The sock electrode rendered external defibrillation impossible, however, even at 360 J.

CONCLUSION

Skeletal muscle activation induced by ICD shocks can be greatly reduced using an electrode system that confines the electric shock field to the heart. Refinement of this strategy may allow for delivery of painless shocks by ICDs. Further development is needed to overcome implant complexity and the higher external DFT with this type of electrode system.

Multislice Computed Tomography for Preoperative Evaluation of Right Ventricular Volumes and Function: Comparison With Magnetic Resonance Imaging

BACKGROUND

This study was performed to validate preoperative right ventricular measurements obtained from multislice spiral computed tomography data sets in comparison with magnetic resonance imaging.

METHODS

Before cardiac surgery, 25 patients (among them 12 patients with compromised right ventricular function) underwent contrast-enhanced retrospectively electrocardiogram-gated multislice spiral computed tomography and cine magnetic resonance imaging in a standardized fashion. Right ventricular end-diastolic, end-systolic and stroke volume, ejection fraction, and myocardial mass were calculated according to the slice summation method. Measurements obtained with both modalities were compared using Pearson's correlation coefficient (r), Student's t test for paired samples, and Bland-Altman analysis.

RESULTS

The right ventricle was completely visualized with invariably adequate image quality on all multislice spiral computed tomography and magnetic resonance images. For all measurements a close correlation between multislice spiral computed tomography and magnetic resonance imaging was found (end-diastolic volume, r = 0.93; end-systolic volume, r = 0.95; stroke volume, r = 0.91; ejection fraction, r = 0.96; mass, r = 0.94). Mean values of all measurements did not differ significantly between both modalities, and limits of agreement were in an acceptable range.

CONCLUSIONS

When compared with magnetic resonance imaging as a reference method, multislice spiral computed tomography seems to be an accurate and reliable noninvasive technique for evaluating right ventricular measurements.