Use of a right ventricular continuous flow pump to validate the distensible model of the pulmonary vasculature

In the pulmonary circulation, resistive and compliant properties overlap in the same vessels. Resistance varies nonlinearly with pressure and flow; this relationship is driven by the elastic properties of the vessels. Linehan et al. (1982) correlated the mean pulmonary arterial pressure and mean flow with resistance using an original equation incorporating the distensibility of the pulmonary arteries. The goal of this study was to validate this equation in an in vivo porcine model. In vivo measurements were acquired in 6 pigs. The distensibility coefficient (DC) was measured by placing piezo-electric crystals around the pulmonary artery (PA). In addition to experiments under pulsatile conditions, a right ventricular (RV) bypass system was used to induce a continuous pulmonary flow state. The Linehan's equation was then used to predict the pressure from the flow under continuous flow conditions. The diameter-derived DC was 2.4 %/mmHg (+/- 0.4 %), whereas the surface area-based DC was 4.1 %/mmHg (+/- 0.1 %). An increase in continuous flow was associated with a constant decrease in resistance, which correlated with the diameter-based DC (r=-0.8407, p=0.044) and the surface area-based DC (r=-0.8986, p=0.028). In contrast to the Linehan's equation, our results showed constant or even decreasing pressure as flow increased. Using a model of continuous pulmonary flow induced by an RV assist system, pulmonary pressure could not be predicted based on the flow using the Linehan's equation. Measurements of distensibility based on the diameter of the PA were inversely correlated with the resistance

Adjustable Intragastric Balloons: A 12-Month Pilot Trial in Endoscopic Weight Loss Management

Intragastric balloons are associated with (1) early period intolerance, (2) diminished effect within 3–4 months, and (3) bowel obstruction risk mandating removal at 6 months. The introduction of an adjustable balloon could improve comfort and offer greater efficacy. A migration prevention function, safely enabling prolonged implantation, could improve efficacy and weight maintenance post-extraction. The first implantations of an adjustable balloon with an attached migration prevention anchor are reported. The primary endpoint was the absence of bowel perforation, obstruction, or hemorrhage. Eighteen patients with mean BMI of 37.3 were implanted with the Spatz Adjustable Balloon system (ABS) for 12 months. Balloon volumes were adjusted for intolerance or weight loss plateau. Mean weight loss at 24 weeks was 15.6 kg with 26.4% EWL (percent of excess weight loss) and 24.4 kg with 48.8% EWL at 52 weeks. Sixteen adjustments were successfully performed. Six downward adjustments alleviated intolerance, yielding additional mean weight loss of 4.6 kg. Ten upward adjustments for weight loss plateau yielded a mean additional weight loss of 7 kg. Seven balloons were removed prematurely. Complications necessitating early removal included valve malfunction (1), gastritis (1), Mallory–Weiss tear (1), NSAID (2× dose/2 weeks) perforating ulcer (1), and balloon deflation (1). Two incidents of catheter shear from the chain: one passed uneventfully and one caused an esophageal laceration without perforation during extraction. The Spatz ABS has been successfully implanted in 18 patients. (1) Upward adjustments yielded additional weight loss. (2) Downward adjustments alleviated intolerance, with continued weight loss. (3) Preliminary 1-year implantation results are encouraging

Impact of prosthesis-patient mismatch on mitral regurgitation after aortic valve replacement

Background: Mitral regurgitation is frequently observed in patients undergoing aortic valve replacement (AVR) for aortic stenosis and often improves postoperatively, mainly due to left ventricular remodelling and changes in loading conditions. Aortic prosthesis-patient mismatch (PPM) is associated with poor outcome and lesser left ventricular remodelling. This study tested the hypothesis that aortic PPM affects mitral regurgitation. Methods and results: Echocardiography was performed preoperatively and before discharge in 42 patients with aortic stenosis undergoing isolated AVR and presenting mitral regurgitation with an effective regurgitant orifice (ERO) of 10 mm2 or greater, as assessed by the proximal isovelocity surface area method. Postoperatively, mitral ERO and the regurgitant volume decreased from 16±5 mm2 to 12plusmn;6 mm2 (p<0.001) and from 28plusmn;8 ml to 16plusmn;9 ml (p<0.0001), respectively. PPM (indexed effective prosthetic valve area (EOAi) ≤0.85 cm2/m2), present in 23 patients (55%), was associated with a smaller decrease in regurgitant volume (p=0.0025) and ERO (p=0.02). A functional aetiology of mitral regurgitation was associated with a larger improvement in mitral regurgitation. In the whole cohort, EOAi correlated with the changes in mitral regurgitation severity (ERO r=0.44, p=0.01; regurgitant volume r=0.47, p=0.003). However, these relationships were no longer significant in the subset of patients with functional mitral regurgitation in whom mitral regurgitation changes were mainly related to postoperative changes in mitral valve deformation. Conclusions: The presence of PPM after AVR attenuates postoperative mitral regurgitation changes, mainly in patients with organic mitral regurgitation.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

What happens to functional mitral regurgitation after aortic valve replacement for aortic stenosis?

BACKGROUND: Patients with aortic stenosis (AS) treated with aortic valve replacement (AVR) may also present with associated functional mitral valve regurgitation (FMR). Whether to also address the mitral valve at the time of AVR remains unclear. This study was designed to determine the influence of MR on survival and its evolution over time. METHODS: We retrospectively reviewed 74 patients with FMR who underwent isolated AVR between 1999 and 2006 at our institution. Inclusion criteria were surgery for AVR with severe AS (mean age, 69 years; N = 47; 64% women) and FMR (grade I, 80%; grade II, 19%; grade III, 1%). Echocardiography follow-up data were obtained by mail questionnaires sent to the referring cardiologists of all survivors. All parameters were analyzed with the Kaplan-Meier method and the sign test. RESULTS: The operative mortality rate was 2%, and 9 patients (12%) died during follow-up. The mean (SD) follow-up time was 48 ± 33 months, and follow-up 96% complete. The follow-up demonstrated a decrease of FMR by 2 degrees in 3 patients (4%), and 1 degree in 14 patients (19%); regurgitation remained unchanged in the majority of patients (n = 47; 63%). FMR worsened in 10 patients overall (14%), and new-onset atrial fibrillation was found in 24 patients (33%); however, the statistical analysis failed to demonstrate an impact of worsening FMR on survival. CONCLUSION: MR in patients with severe AS and FMR at the time of AVR does not appear to worsen significantly over time. Not dealing with the mitral valve at the time of AVR might be warranted for selected patients

Report from the 4th European Bone Sarcoma Networking meeting: focus on osteosarcoma

Development and application of statistical models for medical scientific researc