Impact of maternal posture on fetal physiology in human pregnancy: a narrative review.

In numerous medical conditions, including pregnancy, gravity and posture interact to impact physiology and pathophysiology. Recent investigations, for example, pertaining to maternal sleeping posture during the third trimester and possible impact on fetal growth and stillbirth risk highlight the importance and potential clinical implications of the subject. In this review, we provide an extensive discussion of the impact of maternal posture on fetal physiology from conception to the postpartum period in human pregnancy. We conducted a systematic literature search of the MEDLINE database and identified 242 studies from 1991 through 2021, inclusive, that met our inclusion criteria. Herein, we provide a synthesis of the resulting literature. In the first section of the review, we group the results by the impact of maternal posture at rest on the cervix, uterus, placenta, umbilical cord, amniotic fluid, and fetus. In the second section of the review, we address the impact on fetal-related outcomes of maternal posture during various maternal activities (e.g., sleep, work, exercise), medical procedures (e.g., fertility, imaging, surgery), and labor and birth. We present the published literature, highlight gaps and discrepancies, and suggest future research opportunities and clinical practice changes. In sum, we anticipate that this review will shed light on the impact of maternal posture on fetal physiology in a manner that lends utility to researchers and clinicians who are working to improve maternal, fetal, and child health.

Navigating the Regulatory Pathway for Medical Devices-a Conversation with the FDA, Clinicians, Researchers, and Industry Experts.

Successful translation of new and innovative medical products from concept to clinical use is a complex endeavor that requires understanding and overcoming a variety of challenges. In particular, regulatory pathways and processes are often unfamiliar to academic researchers and start-ups, and even larger companies. Growing evidence suggests that the successful translation of ideas to products requires collaboration and cooperation between clinicians, researchers, industry, and regulators. A multi-stakeholder group developed this review to enhance regulatory knowledge and thereby improve translational success for medical devices. Communication between and among stakeholders is identified as a critical factor. Current regulatory programs and processes to facilitate communication and translation of innovative devices are described and discussed. Case studies are used to highlight the importance of flexibility when considering evidence requirements. We provide a review of emerging strategies, opportunities, and best practices to increase the regulatory knowledge base and facilitate medical device translation by all stakeholders. Clinicians, regulators, industry, and researchers require regulatory knowledge and collaboration for successful translation of innovative medical devices.

Toward Automation of the Supine Pressor Test for Preeclampsia.

Preeclampsia leads to increased risk of morbidity and mortality for both mother and fetus. Most previous studies have largely neglected mechanical compression of the left renal vein by the gravid uterus as a potential mechanism. In this study, we first used a murine model to investigate the pathophysiology of left renal vein constriction. The results indicate that prolonged renal vein stenosis after 14 days can cause renal necrosis and an increase in blood pressure (BP) of roughly 30 mmHg. The second part of this study aimed to automate a diagnostic tool, known as the supine pressor test (SPT), to enable pregnant women to assess their preeclampsia development risk. A positive SPT has been previously defined as an increase of at least 20 mmHg in diastolic BP when switching between left lateral recumbent and supine positions. The results from this study established a baseline BP increase between the two body positions in nonpregnant women and demonstrated the feasibility of an autonomous SPT in pregnant women. Our results demonstrate that there is a baseline increase in BP of roughly 10-14 mmHg and that pregnant women can autonomously perform the SPT. Overall, this work in both rodents and humans suggests that (1) stenosis of the left renal vein in mice leads to elevation in BP and acute renal failure, (2) nonpregnant women experience a baseline increase in BP when they shift from left lateral recumbent to supine position, and (3) the SPT can be automated and used autonomously.

Can preeclampsia be considered a renal compartment syndrome? A hypothesis and analysis of the literature.

The morbidity and mortality associated with preeclampsia is staggering. The physiology of the Page kidney, a condition in which increased intrarenal pressure causes hypertension, appears to provide a unifying framework to explain the complex pathophysiology. Page kidney hypertension is renin-mediated acutely and ischemia-mediated chronically. Renal venous outflow obstruction also causes a Page kidney phenomenon, providing a hypothesis for the increased vulnerability of a subset of women who have what we are hypothesizing is a "renal compartment syndrome" due to inadequate ipsilateral collateral renal venous circulation consistent with well-known variation in normal venous anatomy. Dynamic changes in renal venous anatomy and physiology in pregnancy appear to correlate with disease onset, severity, and recurrence. Since maternal recumbent position is well known to affect renal perfusion and since chronic outflow obstruction makes women vulnerable to the ischemic/inflammatory sequelae, heightened awareness of renal compartment syndrome physiology is critical. The anatomic and physiologic insights provide immediate strategies to predict and prevent preeclampsia with straightforward, low-cost interventions that make renewed global advocacy for pregnant women a realistic goal.

Cost-utility analysis of percutaneous mitral valve repair in inoperable patients with functional mitral regurgitation in German settings.

BACKGROUND: To determine the cost-effectiveness of the percutaneous mitral valve repair (PMVR) using Carillon® Mitral Contour System® (Cardiac Dimensions Inc., Kirkland, WA, USA) in patients with congestive heart failure accompanied by moderate to severe functional mitral regurgitation (FMR) compared to the prolongation of optimal medical treatment (OMT). METHODS: Cost-utility analysis using a combination of a decision tree and Markov process was performed. The clinical effectiveness was determined based on the results of the Transcatheter Implantation of Carillon Mitral Annuloplasty Device (TITAN) trial. The mean age of the target population was 62 years, 77% of the patients were males, 64% of the patients had severe FMR and all patients had New York Heart Association functional class III. The epidemiological, cost and utility data were derived from the literature. The analysis was performed from the German statutory health insurance perspective over 10-year time horizon. RESULTS: Over 10 years, the total cost was €36,785 in the PMVR arm and €18,944 in the OMT arm. However, PMVR provided additional benefits to patients with an 1.15 incremental quality-adjusted life years (QALY) and an 1.41 incremental life years. The percutaneous procedure was cost-effective in comparison to OMT with an incremental cost-effectiveness ratio of €15,533/QALY. Results were robust in the deterministic sensitivity analysis. In the probabilistic sensitivity analysis with a willingness-to-pay threshold of €35,000/QALY, PMVR had a 84 % probability of being cost-effective. CONCLUSIONS: Percutaneous mitral valve repair may be cost-effective in inoperable patients with FMR due to heart failure.

Treatment of functional mitral regurgitation by percutaneous annuloplasty: results of the TITAN Trial.

AIMS: Functional mitral regurgitation (FMR) contributes to morbidity and mortality in heart failure (HF) patients. The aim of this study was to determine whether percutaneous mitral annuloplasty could safely and effectively reduce FMR and yield durable long-term clinical benefit. METHODS AND RESULTS: The impact of mitral annuloplasty (Carillon Mitral Contour System) was evaluated in HF patients with at least moderate FMR. Patients in whom the device was placed then acutely recaptured for clinical reasons served as a comparator group. Quantitative measures of FMR, left ventricular (LV) dimensions, New York Heart Association (NYHA) class, 6 min walk distance (6MWD), and quality of life were assessed in both groups up to 12 months. Safety and key functional data were assessed in the implanted cohort up to 24 months. Thirty-six patients received a permanent implant; 17 had the device recaptured. The 30-day major adverse event rate was 1.9%. In contrast to the comparison group, the implanted cohort demonstrated significant reductions in FMR as represented by regurgitant volume [baseline 34.5 ±11.5 mL to 17.4 ±12.4 mL at 12 months (P < 0.001)]. There was a corresponding reduction in LV diastolic volume [baseline 208.5 ±62.0 mL to 178.9 ±48.0 mL at 12 months (P =0.015)] and systolic volume [baseline 151.8 ±57.1 mL to 120.7 ±43.2 mL at 12 months (P =0.015)], compared with progressive LV dilation in the comparator. The 6MWD markedly improved for the implanted patients by 102.5 ±164 m at 12 months (P =0.014) and 131.9 ±80 m at 24 months (P < 0.001). CONCLUSION: Percutaneous reduction of FMR using a coronary sinus approach is associated with reverse LV remodelling. Significant clinical improvements persisted up to 24 months.

Effectiveness and safety of percutaneous coronary sinus-based mitral valve repair in patients with dilated cardiomyopathy (from the AMADEUS trial).

This report presents the procedural results from the AMADEUS trial that support coronary sinus (CS)-based percutaneous mitral annuloplasty. Despite therapeutic advances, functional mitral regurgitation (MR) continues to be a significant clinical problem for patients with dilated cardiomyopathy. CS approaches to mitral valve repair have been viewed with skepticism because of the distance of the CS/great cardiac vein from the mitral valve annulus and the potential to compress a coronary artery. This report presents the procedural results from the AMADEUS trial that support CS-based percutaneous mitral annuloplasty. Patients who met the inclusion criteria were eligible to receive a mitral annuloplasty device. Transesophageal echocardiography was used to assess changes in MR, angiography was used to assess the coronary arteries, and multislice computed tomography was used to evaluate the anatomic relations between the coronary venous system and the mitral valve. Acute MR reduction (grade 3.0 +/- 0.6 to 2.0 +/- 0.8, p <0.0001) and permanent implantation were achieved in 30 of 43 patients in whom an attempt was made. Additional measurements in 20 patients with implants showed reductions in the vena contracta (0.69 +/- 0.29 to 0.46 +/- 0.26 cm, p <0.0001), effective regurgitant orifice area (0.33 +/- 0.17 to 0.19 +/- 0.08 cm(2), p <0.0001), regurgitant volume (40 +/- 20 to 24 +/- 11 ml, p = 0.0005), and jet area/left atrial area (45 +/- 13% to 32 +/- 12%, p <0.0001). The coronary arteries were crossed in 36 patients (84%). Arterial compromise contributed to a lack of implantation in 6 patients (14%). No difference was found in the CS/great cardiac vein position relative to the annulus between the patients who did and did not have a reduction in MR. In conclusion, percutaneous mitral annuloplasty reduces MR and permanent implantation can be achieved in most eligible patients.

Percutaneous mitral annuloplasty for functional mitral regurgitation: results of the CARILLON Mitral Annuloplasty Device European Union Study.

BACKGROUND: Functional mitral regurgitation (FMR), a well-recognized component of left ventricular remodeling, is associated with increased morbidity and mortality in heart failure patients. Percutaneous mitral annuloplasty has the potential to serve as a therapeutic adjunct to standard medical care. METHODS AND RESULTS: Patients with dilated cardiomyopathy, moderate to severe FMR, an ejection fraction <40%, and a 6-minute walk distance between 150 and 450 m were enrolled in the CARILLON Mitral Annuloplasty Device European Union Study (AMADEUS). Percutaneous mitral annuloplasty was achieved through the coronary sinus with the CARILLON Mitral Contour System. Echocardiographic FMR grade, exercise tolerance, New York Heart Association class, and quality of life were assessed at baseline and 1 and 6 months. Of the 48 patients enrolled in the trial, 30 received the CARILLON device. Eighteen patients did not receive a device because of access issues, insufficient acute FMR reduction, or coronary artery compromise. The major adverse event rate was 13% at 30 days. At 6 months, the degree of FMR reduction among 5 different quantitative echocardiographic measures ranged from 22% to 32%. Six-minute walk distance improved from 307+/-87 m at baseline to 403+/-137 m at 6 months (P<0.001). Quality of life, measured by the Kansas City Cardiomyopathy Questionnaire, improved from 47+/-16 points at baseline to 69+/-15 points at 6 months (P<0.001). CONCLUSIONS: Percutaneous reduction in FMR with a novel coronary sinus-based mitral annuloplasty device is feasible in patients with heart failure, is associated with a low rate of major adverse events, and is associated with improvement in quality of life and exercise tolerance.

Feasibility and short-term efficacy of percutaneous mitral annular reduction for the therapy of functional mitral regurgitation in patients with heart failure.

BACKGROUND: While functional mitral regurgitation (MR) commonly accompanies heart failure and contributes to heart failure progression, mitral repair in the setting of HF is not routinely practiced because of the attendant significant morbidity and mortality. This limitation has fostered the development of percutaneous devices to reduce MR, and our group has recently reported the short- and long-term effectiveness of a percutaneous mitral annuloplasty device placed in the coronary sinus (Percutaneous Mitral Annuloplasty Device (PMAD), Cardiac Dimensions(R), Inc., Kirkland, WA) in reducing MR in experimental animal models of heart failure with associated MR. In this article, we report results of a "first-in-human" study of temporary placement of the PMAD device. The aim of this study was to demonstrate the feasibility and safety of temporary deployment of this device in patients with functional MR in association with heart failure. METHODS: Five patients undergoing scheduled coronary angiography with heart failure and functional MR (mean age 52 +/- 9 [SD] years) were recruited, and four had anatomy suitable for deployment of the device. Transthoracic echocardiography and coronary angiography were performed before and after temporary placement and tensioning of the PMAD via the right internal jugular vein. RESULTS: Temporary deployment of the device resulted in a significant reduction in the septal-lateral mitral annular dimension from 35.5 +/- 4.7 to 32.2 +/- 4.6 mm (P = 0.02), with evidence of a reduction in the MR color Doppler area from 98.3 +/- 43.6 to 83.3 +/- 35.1 mm(2) (P = 0.09). There were no complications. CONCLUSIONS: This first-in-human study of a novel device for percutaneous treatment of functional MR has shown that temporary placement of this device in the coronary sinus/great cardiac vein of patients with heart failure and MR is feasible and safe. Evidence of temporary reduction in MR and a reduction in mitral annular area indicate promise for device effectiveness in chronic implantation.

Percutaneous mitral annular reduction provides continued benefit in an ovine model of dilated cardiomyopathy.

BACKGROUND: Functional mitral valve regurgitation plays a key role in the symptomatic severity and progression of heart failure. In an ovine model of dilated cardiomyopathy, we examined the chronic functional consequences of mitral regurgitation reduction using a recently developed novel percutaneous mitral annular reduction (PMAR) device. METHODS AND RESULTS: Fourteen adult sheep were paced right ventricularly at 180 to 190 bpm for 5 weeks, leading to the development of moderate mitral valve regurgitation. After echocardiographic, hemodynamic, and neurohormonal analysis, 9 animals underwent PMAR. All animals were subsequently paced for another 28 days, and a final echocardiographic and hemodynamic study was conducted. Animals that had undergone PMAR showed significantly increased negative and positive dP/dt, whereas pulmonary capillary wedge pressure and mitral valve regurgitation were significantly reduced compared with those at device implant despite continued pacing. In conjunction, significant improvements in plasma norepinephrine and brain natriuretic peptide were apparent. CONCLUSIONS: The application of PMAR in animals with pacing-induced dilated cardiomyopathy and functional mitral valve regurgitation resulted in continued improvements in hemodynamic and neurohormonal parameters.

Acute and chronic reduction of functional mitral regurgitation in experimental heart failure by percutaneous mitral annuloplasty.

OBJECTIVES: We sought to determine acute and chronic efficacy of a percutaneous mitral annuloplasty (PMA) device in experimental heart failure (HF). Further, we evaluated the potential for adverse effects on left ventricular (LV) function and coronary perfusion. BACKGROUND: Reduction of mitral annular dimension with a PMA device in the coronary sinus may reduce functional mitral regurgitation (MR) in advanced HF. METHODS: Study 1: a PMA device was placed acutely in anesthetized open-chest dogs with rapid pacing-induced HF (n = 6) instrumented for pressure volume analysis. Study 2: in 12 anesthetized dogs with HF, fluoroscopic-guided PMA was performed, and dogs were followed for four weeks with continuing rapid pacing. RESULTS: Study 1: percutaneous mitral annuloplasty reduced annular dimension and severity of MR at baseline and with phenylephrine infusion to increase afterload (MR jet/left atrial [LA] area 26 +/- 1% to 7 +/- 2%, p < 0.05). Pressure volume analysis demonstrated no acute impairment of LV function. Study 2: no device was placed in two dogs because of prototype size limitations. Attempted PMA impaired coronary flow in three dogs. Percutaneous mitral annuloplasty (n = 7) acutely reduced MR (MR jet/LA area 43 +/- 4% to 8 +/- 5%, p < 0.0001), regurgitant volume (14.7 +/- 2.1 ml to 3.1 +/- 0.5 ml, p < 0.05), effective regurgitant orifice area (0.130 +/- 0.010 cm(2) to 0.040 +/- 0.003 cm(2), p < 0.05), and angiographic MR grade (2.8 +/- 0.3 device to 1.0 +/- 0.3 device, p < 0.001). In the conscious state, MR was reduced at four weeks after PMA (MR jet/LA area 33 +/- 3% HF baseline vs. 11 +/- 4% four weeks after device, p < 0.05) CONCLUSIONS: Percutaneous mitral annuloplasty results in acute and chronic reduction of functional MR in experimental HF.