Surgical relocation of the papillary muscles in functional ischemic mitral regurgitation: what are the forces of the relocation stitches acting on the myocardium?

BACKGROUND AND AIM OF THE STUDY: In patients with chronic functional ischemic mitral regurgitation (FIMR), papillary muscle relocation has the potential to induce reverse left ventricular remodeling. However, in order to optimize function and durability, the forces imposed on the left ventricular myocardium by papillary muscle relocation should be assessed. METHODS: Eight pigs with FIMR were subjected to down-sized ring annuloplasty in combination with relocation of the anterior (5 mm) and posterior (15 mm) papillary muscles towards the respective trigone. Papillary muscle relocation was obtained by a 2-0 expanded polytetrafluoroethylene stitch fixed to the trigone, exteriorized through the myocardium overlying the papillary muscle, and fixed to an epicardial disc. Tension in these stitches was measured at a systolic blood pressure > 80 mmHg using a custom-made sliding caliper with a strain gauge mounted in line. This allowed assessment of the cyclic change from minimal diastolic to maximum systolic papillary muscle relocation stitch tension. RESULTS: Maximum cyclic change in the posterior papillary muscle (PPM) stitch tension was 1.1 N at 15 mm relocation. In comparison, the anterior papillary muscle (APM) tension was increased to a maximum of 1.4 N with only 5 mm relocation. Surprisingly, during each step of isolated PPM relocation, the APM stitch tension increased concomitantly, but in contrast APM relocation did not influence the magnitude of PPM stitch tension. There was no statistically significant difference between cyclic changes in APM and PPM stitch tension at any step of relocation. CONCLUSION: Papillary muscle relocation using stitches attached between epicardial discs and respective trigones induced a cyclic change in papillary muscle relocation stitch tension of 1.1-1.4 N. These values were in the range of normal tension in the mitral valve apparatus, and equivalent to only 19-24% of the total papillary muscle forces. Therefore, this technique does not appear to induce a non-physiologically high cyclic load on the mitral valve complex.

Impact of papillary muscle relocation as adjunct procedure to mitral ring annuloplasty in functional ischemic mitral regurgitation.

BACKGROUND: The optimal surgical treatment in functional ischemic mitral regurgitation (FIMR) remains controversial. Recently, a posterior papillary muscle relocation (PMR) technique as adjunct procedure to ring annuloplasty has been proposed to prevent recurrent FIMR. In the present study, we used 3D cardiac MRI to assess the impact of relocating both papillary muscles as adjunct procedure to downsized ring annuloplasty on mitral leaflet coaptation geometry in FIMR pigs. METHODS AND RESULTS: Eleven FIMR pigs were randomized to downsized ring annuloplasty (RA; n=6) or RA combined with PMR (RA+PMR, n=5). In the RA+PMR group, a 2-0 Gore-Tex suture was attached to each trigone, exteriorized through the corresponding papillary muscle, mounted on an epicardial pad, and tightened to relocate the myocardium adjacent to the anterior and posterior papillary muscles 5 and 15 mm, respectively. Using 3D MRI, the impact from these interventions on leaflet geometry was assessed. The distance from the posterior papillary muscle to the anterior trigone was reduced significantly more (median values) in the RA+PMR compared with RA animals at end-diastole (-7.9% versus 3.8%, P<0.01) and end-systole (-9.7% versus 2.5%, P=0.02). Accordingly, lateral tethering of the coaptation point (median values) was reduced significantly more in RA+PMR compared with RA animals (-42.8% versus -29.1%, P<0.01). CONCLUSIONS: Adding papillary muscle relocation to downsized ring annuloplasty reduced lateral leaflet tethering in a porcine experimental model of FIMR. Therefore, this technique holds promise for reducing persistent and recurrent FIMR in patients.

Detection of Lymph Node Metastasis in Patients with Bladder Cancer using Maximum Standardised Uptake Value and 18F-fluorodeoxyglucose Positron Emission Tomography/Computed Tomography: Results from a High-volume Centre Including Long-term Follow-up.

BACKGROUND: Preoperative staging with 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) combined with computed tomography (CT) is used for the evaluation of metastatic disease in patients with invasive bladder cancer. The use of quantification with maximum standardized uptake value (SUVmax) of regional lymph nodes (LNs) has been suggested to increase the diagnostic ability for detection of malignancy. OBJECTIVE: Assessment of the utility and clinical relevance of SUVmax in 18F-FDG PET in detecting regional nodal metastases in patients considered for radical cystectomy. DESIGN, SETTING, AND PARTICIPANTS: From 2011 to 2014, we identified a total of 119 patients with urothelial carcinoma who underwent radical cystectomy with extended LN dissection; additionally, 12 patients were identified by preoperative biopsy. All patients underwent 18F-FDG PET/CT before treatment recommendation. Pathological findings were compared with preoperative PET/CT staging and analysed in a regional- or patient-based model according to SUVmax values. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: In total, 2291 LNs were identified in 131 patients; locoregional involvement of 85 LNs were confirmed in 34 patients. RESULTS AND LIMITATIONS: SUVmax >2 analysis: sensitivity±95% confidence interval of 79.4% (62.1-91.3) and specificity 66.5% (55.7-75.3). SUVmax >4 based analysis: sensitivity was 61.8% (43.6-77.8) and specificity was 84.5% (75.8-91.1). Two years of follow-up implied that higher SUVmax is correlated with higher recurrence risk, independent of conventional pathological findings. CONCLUSIONS: 18F-FDG PET/CT using SUVmax of LNs is a useful tool for preoperative evaluation of pelvic LN metastases from invasive bladder cancer and contributes to the selection of patients for personalized treatment. PATIENT SUMMARY: In this report, we establish that it is possible to identify disease from bladder cancer in the lymphatic tissue surrounding the bladder using a scan analysis. This assists in the selection of treatment for patients with bladder cancer and may spare patients from unnecessary procedures.

Bone healing after median sternotomy: a comparison of two hemostatic devices.

BACKGROUND: Bone wax is traditionally used as part of surgical procedures to prevent bleeding from exposed spongy bone. It is an effective hemostatic device which creates a physical barrier. Unfortunately it interferes with subsequent bone healing and increases the risk of infection in experimental studies. Recently, a water-soluble, synthetic, hemostatic compound (Ostene®) was introduced to serve the same purpose as bone wax without hampering bone healing. This study aims to compare sternal healing after application of either bone wax or Ostene®. METHODS: Twenty-four pigs were randomized into one of three treatment groups: Ostene®, bone wax or no hemostatic treatment (control). Each animal was subjected to midline sternotomy. Either Ostene® or bone wax was applied to the spongy bone surfaces until local hemostasis was ensured. The control group received no hemostatic treatment. The wound was left open for 60 min before closing to simulate conditions alike those of cardiac surgery. All sterni were harvested 6 weeks after intervention.Bone density and the area of the bone defect were determined with peripheral quantitative CT-scanning; bone healing was displayed with plain X-ray and chronic inflammation was histologically assessed. RESULTS: Both CT-scanning and plain X-ray disclosed that bone healing was significantly impaired in the bone wax group (p < 0.01) compared with the other two groups, and the former group had significantly more chronic inflammation (p < 0.01) than the two latter. CONCLUSION: Bone wax inhibits bone healing and induces chronic inflammation in a porcine model. Ostene® treated animals displayed bone healing characteristics and inflammatory reactions similar to those of the control group without application of a hemostatic agent.