Cardiac computed tomography for therapy targeting in surgical repair of anteroapical left ventricular aneurysms: assessment of aneurysm volume and of anticipated residual left ventricular volume

Funding Acknowledgements

Type of funding sources: None.

Background

Surgical ventricular repair (SVR) is an established treatment option in patients with heart failure (HF) due to left ventricular (LV) aneurysms, whereby LV volume reduction is the principal therapeutic target. Precise planning therefore is essential for postoperative improvement of HF symptoms.

Purpose

In this study we evaluated the potential of cardiac computed tomography (CCT) to estimate the aneurysm volume and to predict the achievable residual LV volume.

Methods

 205 patients (11/2005-01/2016, m:w = 151:54, median 63.4 years; mean NYHA class 3.03) with anteroapical LV aneurysm underwent SVR combined with coronary artery bypass grafting (77%), mitral valve repair/replacement (19%), and LV thrombectomy (19%). CCT was performed before and 7 days after surgery. Volumetric assessment was made using dedicated software (syngo.via Cardiac Function, Siemens AG).  Preoperative CCT data of 48 consecutive patients were analyzed and then matched with effectively achieved postoperative volumes. To separate the aneurysm volume in the systole and diastole a plane determined by three landmarks on borders of scared to intact LV myocardium (antero-septal, lateral and inferior) was used. In this way ensued the retrospective estimation of the aneurysm volume (AnV/AnVI) and anticipated LV end diastolic and end systolic volume (LVEDVI, LVESVI).

Results

Mean diastolic and systolic estimated AnV were 92 ± 56.6 ml and 83.5 ± 61.6 ml respectively. Relation of AnV to LVEDV and to LVESV was 29.2% and 38.2%, correspondingly. There was significant correlation between anticipated and effectively achieved LVEDV and LVESV (r = 0.87 and r = 0.88, respectively, p < 0.0001), and their indexed values (r = 0.83 and r = 0.83, respectively, p < 0.0001). Anticipated LVEDVI was only 10.3 ± 22.5 ml/m2 greater than achieved LVEDVI (p = 0.003), and anticipated LVESVI was only 2.4 ± 20.3 ml/m2 greater than achieved LVESVI (p = 0.433).

Conclusions

Estimation of aneurysm volume and anticipated postoperative LV volume allows to predict if the therapeutic targets can be successfully achieved in individual patients. Based on the CCT assessment we propose an approach for surgical planning in anterior LV aneurysms.

Use of an intravascular gas exchanger: is low systemic heparinization safe?

Extracorporeal membrane oxygenation (ECMO) is a cumbersome procedure. Alternatively, mechanical lung assist can be realized with an intravascular gas exchanger (IVOX). To assess the degree of initial anticoagulation required during intravascular lung assist, we evaluated two regimens of systemic heparinization in 10 bovine experiments. The animals were randomly assigned to two groups with either full systemic heparinization (heparin loading dose 300 IU/kg bodyweight; activated coagulation time (ACT) > 480 s) or low systemic heparinization (heparin loading dose 100 IU/kg bodyweight; ACT > 180 s). The surface heparinized intravascular gas exchanger was placed in the caval axis under fluoroscopic control, and a standard battery of blood samples was drawn before and at regular intervals during the procedure. After six hours of intravascular lung assist the device was explanted, drained, weighed, and carefully analysed. Preassist haematocrit was 25 ± 5% for full versus 24 ± 7% for low (NS) as compared with 23 ± 8% for full versus 26 ± 3% for low (NS) postassist. Platelet levels were 100 ± 25 for full versus 100 ± 21 % for low (NS) preassist as compared with 64 ± 22% for full versus 78 ± 22% for low (NS) postassist. Mean ACT was 157 ± 12 s for full versus 158 ± 18 for low (NS) preassist as compared with 800 ± 244 s versus 219 ± 25 for low (p < 0.05) postassist. Thrombin time was 20 ± 2 s for full versus 23 ± 2 s for low (NS) as compared with > 200 s for both groups after assist. Relative fibrinopeptide A levels were 7.3 ± 1.1 ng/ml for full versus 6.3 ± 1.6 ng/ml for low (NS) preassist as compared with 4.7 ± 4.1 ng/ml for full versus 5.8 ± 0.9 ng/ml for low (NS) postassist. CO2 transfer was 40 ± 10 ml/min for full versus 36 ± 10 ml/min for low (NS) at the begining as compared with 45 ± 25 ml/min for full versus 46 ± 15 for low (NS) at the end. Weight increase due to device deposits (clots) was 14 ± 11 g for full versus 13 ± 10 g for low systemic heparinization (NS). Intravascular lung assist with low versus full systemic heparinization appeared to result in similar activation of the coagulation system, device deposits and gas transfer rates. Considering our clinical experience we can say that application of the device with reduced systemic heparinization is useful in selected patients.

Optimum load in various vertical jumps support the maximum dynamic output hypothesis

The aim was to generalize the maximum dynamic output (MDO) hypothesis [i. e., the muscle power output in vertical jumps (VJ) is maximized when loaded with one's own body mass] to variety of VJ. We hypothesized that the subjects' own body (a) would be the optimal load for maximizing the power output (i. e., the no-load condition) and also (b) reveal the maximum benefits of stretch-shortening cycle (SSC). 13 participants performed the maximum squat and various counter-movement jumps when loaded by approximately constant external force ranging from -40% to  + 40% of their body weight (BW). Regarding the first hypothesis, the differences in both the peak and mean power recorded under different load magnitudes revealed maxima close to no-load condition (i. e., from -3% BW to  + 8% BW; R2=0.65-0.96; all P<0.01). Regarding the second hypothesis, the differences in performance between VJ executed with and without SSC also revealed maxima close to no-load conditions (0-2% BW), while the same differences in the power output were observed under relatively low positive loads (14-25% BW; R² = 0.56-0.95; all P<0.01). The findings support the concept that maximal power output occurs close to one's own body mass during VJ with and without SSC, thereby providing additional support to MDO hypothesis.

[Improvements in implantable mechanical circulatory support systems : literature overview and update]

In recent years, ventricular assist devices (VAD) supporting the left (LVAD), the right (RVAD) or both ventricles (BVAD) have rapidly emerged as the standard of care for advanced heart failure patients. Both the numbers and ages of patients in which they are used are rising worldwide, especially when used as a permanent support (bridge to destination, BTD). Due to the continuing lack of donor organs, these devices now represent a viable alternative to bridge patients to transplantation (BTT), with a 1-year survival rate of 86%. BTD, especially in long-term support, might be a valid, and the sole, option for those patients in whom heart transplantation is contraindicated. Patient selection, pre- and intra-operative preparation, as well as the timing of VAD implantation are important factors critical to successful circulatory support. While BTT remains the goal in the majority of patients, the number of permanent VADs (i. e. BTD) is rising significantly. Although explantation of a VAD system as a bridge to recovery (BTR) can be considered in only a small number of patients, it represents a very special part of this therapy modality.