High prevalence of obstructive sleep apnea in a surgical aortic valve replacement cohort: an observational study.

Study Objectives: A high prevalence of sleep apnea has been reported among transcatheter aortic valve replacement (AVR) patients; however, the prevalence of sleep apnea in the younger and relatively healthier population of surgical AVR (SAVR) patients is unknown. Methods: We assessed the prevalence of sleep apnea and overall sleep quality in patients having SAVR. Participants aged 50-89 were eligible for recruitment. All participants completed type II HST before SAVR. Sleep apnea was defined as an apnea-hypopnea index (AHI) ≥ 5 events/hour. The current use of positive airway pressure was exclusionary. Results: The 46 participants (32 males/14 females) had a mean age of 66.6 years, body mass index of 30, AHI of 23.5, and obstructive AHI of 22.0. Only four participants had a prior sleep apnea diagnosis, yet all but one had sleep apnea on type II sleep testing. Two-thirds of sleep apnea was moderate or severe (AHI ≥ 15). A quarter of respiratory events were defined by arousals without desaturations. Whereas most sleep parameters resembled those of similarly aged community cohorts, mean percentage of N3 was reduced, accounting for only 3.8% of total sleep time. Conclusions: Type II home sleep testing (HST) revealed a 97.8% prevalence of sleep apnea in this sample, most of which was undiagnosed obstructive sleep apnea. Roughly two-thirds of sleep apnea was moderate or severe. Such a high impact of obstructive sleep apnea among patients with severe aortic valve disease deserves further investigation on potential underlying mechanisms and clinical implications.

Myosin-5 varies its step length to carry cargo straight along the irregular F-actin track.

Molecular motors employ chemical energy to generate unidirectional mechanical output against a track while navigating a chaotic cellular environment, potential disorder on the track, and against Brownian motion. Nevertheless, decades of nanometer-precise optical studies suggest that myosin-5a, one of the prototypical molecular motors, takes uniform steps spanning 13 subunits (36 nm) along its F-actin track. Here, we use high-resolution interferometric scattering microscopy to reveal that myosin takes strides spanning 22 to 34 actin subunits, despite walking straight along the helical actin filament. We show that cumulative angular disorder in F-actin accounts for the observed proportion of each stride length, akin to crossing a river on variably spaced stepping stones. Electron microscopy revealed the structure of the stepping molecule. Our results indicate that both motor and track are soft materials that can adapt to function in complex cellular conditions.

Health and Social Care Integration in Scotland: Evidence vs Rhetoric.

In this perspective paper we use publicly-available data to show that, despite much positive rhetoric in support of reforms in Scotland to integrate health and social care, these reforms, in their current state, have failed to meet their stated objectives. Rather than regress to the previous system, we propose continued evaluation of even more radical forms of such integration. This analysis, and set of future proposals, are timely given current considerations with respect to a National Care Service in Scotland and recent similar reforms in England and in other countries.

Aortic annulus rupture after transcatheter aortic valve replacement: successful management of a dangerous complication.

OBJECTIVE: Aortic annulus rupture remains one of the most fatal complications of TAVR. While attempts have been made to describe and predict this complication, the data remains insufficient without evidence-based guidelines for management of this rare complication. METHODS: Here we describe a series of 3 aortic annulus ruptures after TAVR which were managed successfully to hospital discharge. RESULTS: Patient 1 suffered annulus rupture during balloon valvuloplasty prior to TAVR. The patient became hypotensive, and echocardiogram showed pericardial effusion. The patient underwent pericardiocentesis which transiently improved the blood pressure, but bleeding continued. The patient was transitioned to an open surgical aortic valve replacement due to ongoing hemorrhage. The chest was left open with delayed closure on post-op day 2. The patient was discharged on post-op day 15. Patient 2 was undergoing TAVR valve expansion. The patient became hypotensive. An echocardiogram revealed pericardial effusion. Pericardiocentesis yielded 200 mL of blood. SURGIFLO (Johnson & Johnson Wound Management, Somerville, NJ) was injected into the pericardial space. Aortic root angiography confirmed no further contrast extravasation. A pericardial drain was left in place for 2 days, and the patient was discharged on post-op day 7. Patient 3 received a TAVR valve and post-placement dilation due to paravalvular leak. The echocardiogram showed a pericardial effusion. Pericardiocentesis was performed, yielding 500 cc of blood. The patient's healthcare proxy declined emergent surgery; thus, a pericardial drain was placed. No hemostatic agents were used, and drainage reduced over several hours. The drain was removed on post-op day 3, and the patient was discharged on post-op day 8. CONCLUSIONS: Based on the timelines in these three cases, and interventions used, the following steps may be employed in the event of annulus rupture: identification of hemodynamic instability, echocardiogram to confirm pericardial effusion, emergent pericardiocentesis, pericardial drain placement for evacuation of the pericardial space and use of hemostatic agents, repeat aortogram to rule out ongoing extravasation. If hemostasis is unable to be achieved and/or the patient becomes hemodynamically unstable at any point, rapid transition to emergent surgical management is necessary. This management strategy proved successful for this case series and warrants further investigation.

The COVID-19 Pandemic and Associated Inequities in Acute Myocardial Infarction Treatment and Outcomes.

Importance: The COVID-19 pandemic disrupted usual care for emergent conditions, such as acute myocardial infarction (AMI). Understanding whether Black and Hispanic individuals experiencing AMI had greater increases in poor outcomes compared with White individuals during the pandemic has important equity implications. Objective: To investigate whether the COVID-19 pandemic was associated with increased disparities in treatment and outcomes among Medicare patients hospitalized with AMI. Design, Setting, and Participants: This cross-sectional study used Medicare data for patients hospitalized with AMI between January 2016 and November 2020. Patients were categorized as Hispanic, non-Hispanic Black, and non-Hispanic White. The association between race and ethnicity and outcomes as a function of the proportion of hospitalized patients with COVID-19 was evaluated using interrupted time series. Data were analyzed from October 2022 to June 2023. Exposure: The main exposure was a hospital's proportion of hospitalized patients with COVID-19 on a weekly basis as a proxy for care disruption during the pandemic. Main Outcomes and Measures: Revascularization, 30-day mortality, 30-day readmission, and nonhome discharges. Results: A total of 1 319 273 admissions for AMI (579 817 females [44.0%]; 122 972 Black [9.3%], 117 668 Hispanic [8.9%], and 1 078 633 White [81.8%]; mean [SD] age, 77 [8.4] years) were included. For patients with non-ST segment elevation MI (NSTEMI) overall, the adjusted odds of mortality and nonhome discharges increased by 51% (adjusted odds ratio [aOR], 1.51; 95% CI, 1.29-1.76; P < .001) and 32% (aOR, 1.32; 95% CI, 1.15-1.52; P < .001), respectively, and the odds of revascularization decreased by 27% (aOR, 0.73; 95% CI, 0.64-0.83; P < .001) among patients hospitalized during weeks with a high hospital COVID-19 burden (>30%) vs patients hospitalized prior to the pandemic. Black individuals with NSTEMI experienced a clinically insignificant 7% greater increase in the odds of mortality (aOR, 1.07; 95% CI, 1.00-1.15; P = .04) for each 10% increase in the COVID-19 hospital burden but no increases in readmissions or nonhome discharges or reductions in revascularization rates compared with White individuals. There were no differential increases in adverse outcomes among Hispanic compared with White patients with NSTEMI based on hospital COVID-19 burden. Increases in hospital COVID-19 burden were not associated with changes in outcomes or the use of revascularization in STEMI overall or by racial or ethnic group. Conclusions and Relevance: This study found that while hospital COVID-19 burden was associated with worse treatment and outcomes for NSTEMI, race and ethnicity-associated inequities did not increase significantly during the pandemic. These findings suggest the need for additional efforts to mitigate outcomes associated with the COVID-19 pandemic for patients admitted with AMI when the hospital COVID-19 burden is substantially increased.

Myosin-5 varies its steps along the irregular F-actin track.

Molecular motors employ chemical energy to generate unidirectional mechanical output against a track. By contrast to the majority of macroscopic machines, they need to navigate a chaotic cellular environment, potential disorder in the track and Brownian motion. Nevertheless, decades of nanometer-precise optical studies suggest that myosin-5a, one of the prototypical molecular motors, takes uniform steps spanning 13 subunits (36 nm) along its F-actin track. Here, we use high-resolution interferometric scattering (iSCAT) microscopy to reveal that myosin takes strides spanning 22 to 34 actin subunits, despite walking straight along the helical actin filament. We show that cumulative angular disorder in F-actin accounts for the observed proportion of each stride length, akin to crossing a river on variably-spaced stepping stones. Electron microscopy revealed the structure of the stepping molecule. Our results indicate that both motor and track are soft materials that can adapt to function in complex cellular conditions.

100 years of Emil Wolf: introduction.

The groundbreaking research and ideas introduced by Emil Wolf continue to inspire researchers and motivate ongoing research in the wave properties of light. This special issue commemorates the legacy of Emil Wolf with research in physical optics, with specific focus on those areas where Wolf was active, such as optical coherence theory, inverse problems, singular optics, imaging, and polarization, and the intersection of these fields of study. Here we discuss the life of Emil Wolf and his influence on optical science and the optics community.

Racial and Ethnic Disparities in Access to Minimally Invasive Mitral Valve Surgery.

Importance: Whether people from racial and ethnic minority groups experience disparities in access to minimally invasive mitral valve surgery (MIMVS) is not known. Objective: To investigate racial and ethnic disparities in the utilization of MIMVS. Design, Setting, and Participants: This cross-sectional study used data from the Society of Thoracic Surgeons Database for patients who underwent mitral valve surgery between 2014 and 2019. Statistical analysis was performed from January 24 to August 11, 2022. Exposures: Patients were categorized as non-Hispanic White, non-Hispanic Black, and Hispanic individuals. Main Outcomes and Measures: The association between MIMVS (vs full sternotomy) and race and ethnicity were evaluated using logistic regression. Results: Among the 103 753 patients undergoing mitral valve surgery (mean [SD] age, 62 [13] years; 47 886 female individuals [46.2%]), 10 404 (10.0%) were non-Hispanic Black individuals, 89 013 (85.8%) were non-Hispanic White individuals, and 4336 (4.2%) were Hispanic individuals. Non-Hispanic Black individuals were more likely to have Medicaid insurance (odds ratio [OR], 2.21; 95% CI, 1.64-2.98; P < .001) and to receive care from a low-volume surgeon (OR, 4.45; 95% CI, 4.01-4.93; P < .001) compared with non-Hispanic White individuals. Non-Hispanic Black individuals were less likely to undergo MIMVS (OR, 0.65; 95% CI, 0.58-0.73; P < .001), whereas Hispanic individuals were not less likely to undergo MIMVS compared with non-Hispanic White individuals (OR, 1.08; 95% CI, 0.67-1.75; P = .74). Patients with commercial insurance had 2.35-fold higher odds of undergoing MIMVS (OR, 2.35; 95% CI, 2.06-2.68; P < .001) than those with Medicaid insurance. Patients operated by very-high volume surgeons (300 or more cases) had 20.7-fold higher odds (OR, 20.70; 95% CI, 12.7-33.9; P < .001) of undergoing MIMVS compared with patients treated by low-volume surgeons (less than 20 cases). After adjusting for patient risk, non-Hispanic Black individuals were still less likely to undergo MIMVS (adjusted OR [aOR], 0.88; 95% CI, 0.78-0.99; P = .04) and were more likely to die or experience a major complication (aOR, 1.25; 95% CI, 1.16-1.35; P < .001) compared with non-Hispanic White individuals. Conclusions and Relevance: In this cross-sectional study, non-Hispanic Black patients were less likely to undergo MIMVS and more likely to die or experience a major complication than non-Hispanic White patients. These findings suggest that efforts to reduce inequity in cardiovascular medicine may need to include increasing access to private insurance and high-volume surgeons.

Efficacy of Intraventricular Sponge Placement to Capture Debris in Aortic Valve Replacement.

Objective: Surgical aortic valve replacement (SAVR) carries the known risk of shedding debris into the left ventricle during valve leaflet excision and annulus debridement. Embolization of this debris may have devastating effects for the patient. Although surgeons have developed methods to mitigate this risk, no data exist as to their efficacy. Herein, we present the first study that evaluates the efficacy of a technique for capturing debris during SAVR. Methods: Our group conducted a prospective case series of 20 patients who underwent SAVR using the insertion of an intraventricular surgical sponge prior to valve leaflet excision and annulus debridement to capture debris. Surgical sponges were grossly, radiographically, and histologically examined for the presence of cellular and acellular debris to determine the efficacy of this technique. Results: Of the 20 surgical sponges analyzed, 15 specimens (75%) registered positivity for cellular and/or acellular debris. Seven sponges (35%) were grossly positive, 15 sponges (75%) were radiographically positive, and 4 sponges (20%) were histologically positive for calcified debris on examination. Conclusions: This is one of the few studies to objectively evaluate a method used to capture debris in SAVR procedures. Our results demonstrate a high frequency of debris captured within intraventricular surgical sponges and confirms the efficacy of this technique. While these data are promising, numerous additional approaches exist to capture debris, and a best practice standard should exist across the specialty.  In addition, this study does not address the clinical outcomes associated with this technique. To these ends, additional data and multicenter collaboration are required.

Role of PDE10A in vascular smooth muscle cell hyperplasia and pathological vascular remodelling.

AIMS: Intimal hyperplasia is a common feature of vascular remodelling disorders. Accumulation of synthetic smooth muscle cell (SMC)-like cells is the main underlying cause. Current therapeutic approaches including drug-eluting stents are not perfect due to the toxicity on endothelial cells and novel therapeutic strategies are needed. Our preliminary screening for dysregulated cyclic nucleotide phosphodiesterases (PDEs) in growing SMCs revealed the alteration of PDE10A expression. Herein, we investigated the function of PDE10A in SMC proliferation and intimal hyperplasia both in vitro and in vivo. METHODS AND RESULTS: RT-qPCR, immunoblot, and in situ proximity ligation assay were performed to determine PDE10A expression in synthetic SMCs and injured vessels. We found that PDE10A mRNA and/or protein levels are up-regulated in cultured SMCs upon growth stimulation, as well as in intimal cells in injured mouse femoral arteries. To determine the cellular functions of PDE10A, we focused on its role in SMC proliferation. The anti-mitogenic effects of PDE10A on SMCs were evaluated via cell counting, BrdU incorporation, and flow cytometry. We found that PDE10A deficiency or inhibition arrested the SMC cell cycle at G1-phase with a reduction of cyclin D1. The anti-mitotic effect of PDE10A inhibition was dependent on cGMP-dependent protein kinase Iα (PKGIα), involving C-natriuretic peptide (CNP) and particulate guanylate cyclase natriuretic peptide receptor 2 (NPR2). In addition, the effects of genetic depletion and pharmacological inhibition of PDE10A on neointimal formation were examined in a mouse model of femoral artery wire injury. Both PDE10A knockout and inhibition decreased injury-induced intimal thickening in femoral arteries by at least 50%. Moreover, PDE10A inhibition decreased ex vivo remodelling of cultured human saphenous vein segments. CONCLUSIONS: Our findings indicate that PDE10A contributes to SMC proliferation and intimal hyperplasia at least partially via antagonizing CNP/NPR2/cGMP/PKG1α signalling and suggest that PDE10A may be a novel drug target for treating vascular occlusive disease.

Health and Social Care Reform in Scotland - What Next?

INTRODUCTION: This paper analyses the important enablers, barriers and impacts of country-wide implementation of integrated health and social care in Scotland. It offers insights for other systems seeking to advance similar policy and practice. DESCRIPTION: Landmark legislation was based on a shared vision and narrative about improving outcomes for people and communities. Implementation has involved coordination of multiple policies and interventions for different life stages, care groups, care settings and local context within a dynamic and complex system. DISCUSSION: Relational and citizen led approaches are critical for success, but it takes time to build trusting relationships, influence organisational and professional cultures and cede power. Assessing national impacts is challenging and progress at a national level can seem slower than local experience suggests, due in part to the relative immaturity of national datasets for community interventions. Five years on there are many examples of innovation and positive outcomes despite increasing demographic, workforce, and financial challenges. However, inequalities continue to increase. CONCLUSION: Realising the true value from integration will require a stronger focus on place-based prevention and early intervention to achieve a fairer Scotland where everybody thrives. Solidarity, equity, and human rights must guide the next phase of Scotland's story.

Preoperative anemia management program reduces blood transfusion in elective cardiac surgical patients, improving outcomes and decreasing hospital length of stay.

BACKGROUND: Anemia is an independent risk factor for hospitalization, readmission, prolonged length of stay (LOS), diminished quality of life, and mortality. A multidisciplinary program was implemented to manage anemia preoperatively as a patient blood management (PBM) initiative. METHODS AND MATERIALS: From March 2016 to August 2018, 240 patients were screened for anemia during their preoperative cardiovascular visit. About 52/240 (22%) were found to be anemic and met out inclusion criteria. Also, 45/52 (87%) had iron deficiency anemia and 7 (13%) had anemia without iron deficiency. A similar historical cohort of patients undergoing elective cardiovascular surgery with hemoglobin (Hb) < 12 g/dl from September 2014 to February /2016 (n = 52) served as control group. The primary outcome was perioperative red blood cell (RBC) transfusion. Secondary outcomes were date-of-surgery Hb, intensive care unit (ICU) and hospital LOS, complication rates, and transfusion cost. RESULTS: The two most common treatments were IV iron ± folate (n = 36/45; 80%) and oral iron (n = 9/45; 20%). As compared to historical patients, study patients had significantly higher day-of-surgery Hb (10.6 ± 1.4 vs. 9.8 ± 1.3 g/dl, p < .001), lower utilization of RBC transfusion (0.86 ± 1.4 vs. 2.78 ± 2.4, p < .001), fewer days in the ICU (2.1 ± 2.0 vs. 4.0 ± 3.5, p = .002), and shorter total LOS (6.9 ± 4.8 vs. 12.9 ± 6.8, p < .0001). Study patients also showed lower overall complication rates (p < .0001). Analysis of RBC acquisition cost and transfusion cost also showed significant saving of 69% ($293 vs. $945 and $656 vs. $2116, respectively). CONCLUSION: When corrected for type of procedures and surgeon, our pilot anemia program in elective cardiovascular surgeries showed higher day-of-surgery Hb and significant reduction in RBC transfusion rates, ICU and hospital LOS, and overall complication rates.

Baseline sleep as a predictor of delirium after surgical aortic valve replacement: A feasibility study.

OBJECTIVE: The goal is to assess the feasibility of conducting unattended (type II) sleep studies before surgical aortic valve replacement (SAVR) to examine the relationship between baseline sleep measures and postoperative delirium. METHODS: This single-site study recruited 18 of 20 study referrals with aortic stenosis undergoing first lifetime SAVR. Subjects completed a home-based type II sleep study. Delirium was assessed postoperative days 1-5. Exact logistic regression was used to determine whether sleep efficiency or apnea/hypopnea index predicts delirium. RESULTS: Of 18 study participants, 15 successfully completed a home sleep study (mean age: 71.7 +/- 8.1 years old; 10 male subjects). Five subjects (33.3%) developed delirium. Preliminary analyses found that greater sleep efficiency was associated with a large reduction in delirium odds but was not statistically significant (OR = 0.31, 95% CI: 0.06, 1.03, p = 0.057). The point estimate of the relationship between apnea/hypopnea index and delirium was not similarly sizeable (OR 1.10, 95% CI: 0.35, 3.37, p = 0.85). CONCLUSIONS: Our findings suggest that home type II sleep studies before SAVR are feasible, and they support adequately powered studies investigating type II home sleep studies as a predictor of postoperative delirium and other important postsurgical outcomes.

Impact of COVID-19 on care-home mortality and life expectancy in Scotland.

BACKGROUND: COVID-19 deaths are commoner among care-home residents, but the mortality burden has not been quantified. METHODS: Care-home residency was identified via a national primary care registration database linked to mortality data. Life expectancy was estimated using Makeham-Gompertz models to (i) describe yearly life expectancy from November 2015 to October 2020 (ii) compare life expectancy (during 2016-18) between care-home residents and the wider population and (iii) apply care-home life expectancy estimates to COVID-19 death counts to estimate years of life lost (YLL). RESULTS: Among care-home residents, life expectancy in 2015/16 to 2019/20 ranged from 2.7 to 2.3 years for women and 2.3 to 1.8 years for men. Age-sex-specific life expectancy in 2016-18 in care-home residents was lower than in the Scottish population (10 and 2.5 years in those aged 70 and 90, respectively). Applying care home-specific life expectancies to COVID-19 deaths yield mean YLLs for care-home residents of 2.6 and 2.2 for women and men, respectively. In total YLL care-home residents have lost 3,560 years in women and 2,046 years in men. Approximately half of deaths and a quarter of YLL attributed to COVID-19 were accounted for by the 5% of over-70s who were care-home residents. CONCLUSION: COVID-19 infection has led to the loss of substantial years of life in care-home residents aged 70 years and over in Scotland. Prioritising the 5% of older adults who are care-home residents for vaccination is justified not only in terms of total deaths, but also in terms of YLL.

A Novel Subxiphoid Approach for Bilateral Internal Thoracic Artery Harvesting.

OBJECTIVE: Bilateral internal thoracic artery (BITA) bypass can enable more complete arterial revascularization procedures. Minimally invasive cardiac surgery (MICS) can offer significant patient benefits. New minimally invasive technology for sternal retraction and tissue manipulation is needed to enable ergonomic and reliable minimally invasive ITA harvesting. The goal of this research was to develop technology and techniques, along with experimental testing and training models, for a sternal-sparing approach to in situ BITA harvesting through a small subxiphoid access site. METHODS: This study focused on optimizing custom equipment and methods for subxiphoid BITA harvesting initially in a porcine model (19 pig carcasses, 36 ITAs) and subsequently in 7 cadavers (14 ITAs). RESULTS: Fifty consecutive ITAs were successfully harvested using this remote access approach. The last 20 ITA specimens harvested from the porcine model were explanted and measured; the average length of the free ITA grafts was 12.8 ± 0.9 cm (range 10.8 to 14.2 cm) with a mean time of 23.3 ± 5.2 minutes (range 13 to 25 minutes) for each harvest. CONCLUSIONS: Early results demonstrate that both ITAs can be reliably harvested in a skeletonized fashion in situ through sternal-sparing, small subxiphoid access in 2 experimental models. This innovative approach warrants further exploration toward facilitating complete arterial revascularization and the further adoption of minimally invasive coronary artery bypass graft surgery.

Early Outcomes of Isolated Aortic Valve Replacement Through Right Anterior Minithoracotomy Using the Latest-Generation Biological Prosthesis.

OBJECTIVE: The aim of this study is to evaluate early and intermediate outcomes and hemodynamics of the latest-generation Trifecta valve implanted using right anterior minithoracotomy. METHODS: We performed a single-center, retrospective, observational study including 175 individuals who underwent isolated minimally invasive aortic valve replacement with the latest-generation Trifecta valves through a right anterior minithoracotomy between January 2016 and January 2019. Exclusion criteria for follow-up echocardiographic study included concomitant procedures, conversion to median sternotomy, and nonsurvival during the index admission. Analyses addressed implantation safety, 30-day and intermediate-term survival and hemodynamic performance of the valves. RESULTS: Overall, patients were followed with duration ranging from 0.5 to 3 years. Early (<30 days) mortality occurred in 2 patients (1.1%), and there were 9 (5.1%) late (>30 days) deaths. Early thromboembolic events and postoperative bleeding requiring reoperation occurred at a rate of 4.0% (n = 7) and 6.2% (n = 11), respectively. Overall in 175 patients who met inclusion criteria for the follow-up echocardiography study, mean gradients across all valve sizes were 41.3 ± 14.9 (standard deviation) mm Hg preoperatively and remained low at 7.2 ± 3.9 mm Hg with mean effective orifice area of 1.8 ± 0.5 cm2 on the last follow-up echo. There was 1 case of infective prosthetic endocarditis, which did not require valve explant. There were no reoperations due to valve-related problems during the study period. CONCLUSIONS: This is the largest series reporting on outcomes of the latest-generation Trifecta valve implanted using right anterior minithoracotomy. Our results demonstrate that this valve can be safely implanted via a minimally invasive approach with excellent early and intermediate outcomes and hemodynamic performance.

Structure of the shutdown state of myosin-2.

Myosin-2 is essential for processes as diverse as cell division and muscle contraction. Dephosphorylation of its regulatory light chain promotes an inactive, 'shutdown' state with the filament-forming tail folded onto the two heads1, which prevents filament formation and inactivates the motors2. The mechanism by which this happens is unclear. Here we report a cryo-electron microscopy structure of shutdown smooth muscle myosin with a resolution of 6 Å in the head region. A pseudo-atomic model, obtained by flexible fitting of crystal structures into the density and molecular dynamics simulations, describes interaction interfaces at the atomic level. The N-terminal extension of one regulatory light chain interacts with the tail, and the other with the partner head, revealing how the regulatory light chains stabilize the shutdown state in different ways and how their phosphorylation would allow myosin activation. Additional interactions between the three segments of the coiled coil, the motor domains and the light chains stabilize the shutdown molecule. The structure of the lever in each head is competent to generate force upon activation. This shutdown structure is relevant to all isoforms of myosin-2 and provides a framework for understanding their disease-causing mutations.

Routine Placement of Temporary Epicardial Pacing Leads Is Not Required After Minimally Invasive Aortic Valve Replacement.

OBJECTIVE: Our objective is to identify the incidence of urgent transvenous (TV) pacing wire placement following minimally invasive aortic valve replacement (mini-AVR). METHODS: This is a single-center, retrospective, observational study including 359 individuals who underwent isolated mini-AVR through right anterior mini-thoracotomy between January 2015 and September 2019. Patients were grouped according to avoidance or insertion of epicardial pacing wires, and further subdivided based on the requirement for postoperative emergent temporary TV pacing or permanent pacemaker (PPM) placement during the index admission. RESULTS: Two hundred forty-two (67.4%) had acceptable rate and no high-degree atrioventricular (AV) block prior to chest closure and did not have insertion of epicardial pacing wires. Of those patients, only 3 (1.2%) required emergent TV pacing and 6 (2.5%) required nonemergent TV pacing with or without PPM placement during the index admission. Sixty-two (17.3%) patients received only atrial epicardial pacing leads secondary to sinus bradycardia or junctional rhythm and 3 (4.8%) of those patients required PPM placement due to sick sinus syndrome and 1 (1.6%) patient required nonemergent TV pacing and PPM due to high-grade AV heart block. Fifty-five (15.3%) patients received ventricular leads due to high-grade AV heart block and 7 (12.7%) of those patients required PPM placement during the index admission. CONCLUSIONS: Temporary epicardial lead insertion is not routinely required in mini-AVR in patients with normal rate and acceptable AV conduction prior to chest closure. In the absence of epicardial ventricular lead insertion, the chance of requiring urgent TV pacing wire placement during the index admission is 0.99%.