Posterior Mitral Leaflet Left Atrial Anomalous Chord in the Absence of Surgical Mitral Regurgitation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108052/1/echo12582.pd

Failure of Guideline Adherence for Intervention in Patients With Severe Mitral Regurgitation

ObjectivesThis study sought to evaluate the incidence with which adult patients with significant mitral regurgitation (MR) do not undergo surgical intervention despite guideline recommendations, and the associated considerations resulting in no intervention.BackgroundDespite the existence of accepted guidelines, many patients with severe symptomatic heart valve disease might not undergo intervention.MethodsAt a single large tertiary medical center, patients were retrospectively identified who had moderate-to-severe or severe MR on echocardiographic imaging during 2005. Clinical data were reviewed to determine indications for intervention and whether surgery was performed.ResultsDuring 2005, 300 patients were identified with significant MR, including 188 with functional MR and 112 with organic MR. Mitral surgery was performed in 30 of 188 patients with functional MR, mostly to treat heart failure or during another cardiac surgical procedure. Mitral surgery was performed in 59 (53%) of 112 patients with organic MR. Among unoperated patients with organic MR, common reasons included stable left ventricular size or function, absence of symptoms, and prohibitive comorbidities. Using American College of Cardiology/American Heart Association guidelines, 1 or more indication for intervention was present in 39 (74%) of 53 unoperated patients. Perioperative mortality risk was not higher for patients who did not undergo surgery (median 1.2%, interquartile range [IQR] 0.4% to 3.3%) than for those who did (median 1.1%, IQR 0.6% to 5.3%; p = 0.71). During follow-up, there were 12 cardiac and 2 unexplained deaths.ConclusionsAmong patients with severe organic MR, surgical intervention occurred in approximately one-half. However, accepted guideline indications for intervention were present in the majority of unoperated patients. Objectively assessed operative risk was not prohibitive in many unoperated patients

False positive dobutamine stress echocardiograms: Characterization of clinical, echocardiographic and angiographic findings

AbstractObjectives. This study was designed to characterize the clinical, echocardiographic and angiographic findings in patients who have regional wall motion abnormalities predictive of coronary artery disease on dobutamine stress echocardiograms, although coronary angiography reveals no critical stenoses.Background. The specificity of dobutamine stress echocardiography has been reported to be lower than its sensitivity; the sources of false positive findings on dobutamine stress echocardiograms have not been previously defined.Methods. Clinical and echocardiographic characteristics were retrospectively reviewed for patients who had both a dobutamine stress echocardiogram indicate of coronary artery disease on the basis of wall motion abnormalities and <50% stenoses reported on coronary angiography performed within 6 weeks of the echocardiogram. A 16-segment model was used to perform wall motion scoring. Angiograms were independently reviewed, and stenosis severity was quantified with the use of digital calipers.Results. Thirty-nine (11.4%) of 342 studies met criteria for false positive test results, which occurred predominantly in women (72%, p < 0.601). Regional wall motion abnormalities were evident more often in the posterior circulation (62%), and 65% of them were limited to the basal segments. Twelve (28%) of 43 wall motion abnormalities were associated with coronary stenoses of at least intermediate grade (lumen diameter 40.3% to 68.1%). Abnormalities confined to basal segments of the posterior circulation were unlikely to have associated coronary lesions (p = 0.03).Conclusions. False positive findings on dobutamine stress echocardiograms tend to involve small wall motion abnormalities that are frequently located in basal segments of the posterior myocardial circulation. Approximately one third of false positive results occurred in patients with intermediate-grade coronary stenoses, and these studies may reflect true inducible ischemia. Additional sources of false positive study results may include poor endocardial visualization and abnormal motion dye to tethering to the fibrous skeleton of the heart. Altered echocardiographic diagnostic criteria may be appropriate for small wall motion abnormalities confined to basal segments of the posterior circulation

Seeing with sound? Exploring different characteristics of a visual-to-auditory sensory substitution device

Sensory substitution devices convert live visual images into auditory signals, for example with a web camera (to record the images), a computer (to perform the conversion) and headphones (to listen to the sounds). In a series of three experiments, the performance of one such device (‘The vOICe’) was assessed under various conditions on blindfolded sighted participants. The main task that we used involved identifying and locating objects placed on a table by holding a webcam (like a flashlight) or wearing it on the head (like a miner’s light). Identifying objects on a table was easier with a hand-held device, but locating the objects was easier with a head-mounted device. Brightness converted into loudness was less effective than the reverse contrast (dark being loud), suggesting that performance under these conditions (natural indoor lighting, novice users) is related more to the properties of the auditory signal (ie the amount of noise in it) than the cross-modal association between loudness and brightness. Individual differences in musical memory (detecting pitch changes in two sequences of notes) was related to the time taken to identify or recognise objects, but individual differences in self-reported vividness of visual imagery did not reliably predict performance across the experiments. In general, the results suggest that the auditory characteristics of the device may be more important for initial learning than visual associations

The MacKinnon Lists Technique: an efficient new method for rapidly assessing biodiversity and species abundance ranks in the marine environment

Widespread and ever-increasing anthropogenic impacts in the marine environment are driving a need to develop more efficient survey methods for monitoring changes in marine biodiversity. There is a particular urgent need for survey methods that could more rapidly and effectively detect change in species richness, abundance and community composition. Here, test the suitability of the Mackinnon Lists Technique for use in the marine environment by testing its effectiveness for rapid assessment of fish communities. The MacKinnon Lists Technique is a time-efficient and cost-effective sampling method developed for studying avian tropical biodiversity, in which several list samples of species can be collected from a single survey. Using the well-established MaxN approach on data from deployments of a Baited Remote Underwater Video Systems for comparison, we tested the suitability of the MacKinnon Lists Technique for use in marine environments by analysing tropical reef fish communities. Using both methods for each data set, differences in community composition between depths and levels of protection were assessed. Both methods were comparable for diversity and evenness indices with similar ranks for species. Multivariate analysis showed that the MacKinnon Lists Technique and MaxN detected similar differences in community composition at different depths and protection status. However, the MacKinnon Lists Technique detected significant differences between factors when fewer videos (representing reduced survey effort) were used. We conclude that the MacKinnon Lists Technique is at least as effective as the widely used MaxN method for detecting differences between communities in the marine environment and suggest can do so with lower survey effort. The MacKinnon Lists Technique has the potential to be widely used as an effective new tool for rapid conservation monitoring in marine ecosystem

Indexing left ventricular wall thickness to body surface area improves prognostic value

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149205/1/echo14317_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149205/2/echo14317.pd

Dobutamine stress echocardiography

Two-dimensional echocardiography is a versatile, accurate, and readily available method for the assessment of cardiac anatomy and function, and extensive experience has been gained in the analysis of left ventricular wall motion. Using modern imaging techniques, regional as well as global wall motion analysis can be performed. Echocardiography can be used in conjunction with a protocol for either exercise or pharmacologic cardiovascular stress in order to identify the distribution and severity of coronary artery disease, with the induction of a regional wall motion abnormality being a sign of myocardial ischemia. The use of dobutamine infusion to accomplish stress echocardiography is a safe, accurate, and practical method for the diagnosis of coronary artery disease in patients unable to exercise. In addition to the evaluation of inducible ischemia, preliminary work is being performed with dobutamine stress echocardiography for the assessment of risk and patient prognosis following acute myocardial infarction and as an indication of tissue viability for myocardium that remains dysfunctional at rest following thrombolytic therapy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29982/1/0000346.pd

Manus 2006 : hydrothermal systems in the Eastern Manus Basin: fluid chemistry and magnetic structure as guides to subseafloor processes

Cruise Report R/V Melville MAGELLAN-06, Rabaul, Papua New Guinea to Suva, Fiji July 21st 2006 to September 1st 2006The hydrothermal systems in the Manus Basin of Papua New Guinea (PNG) were comprehensively investigated through a combination of sampling and mapping using the Remotely-Operated Vehicle (ROV) Jason, the autonomous underwater vehicle (AUV) ABE (Autonomous Benthic Explorer) and ship-based CTD work and multi-beam bathymetric mapping using the RV Melville. The objectives of the cruise (July 21st to Sept. 1st, 2006) were to identify the tectonic/geologic settings of the vent systems, examine the interactions of seawater with felsic rocks that constitute the high silica end-member range of seafloor basement compositions, determine the extent of volatile magmatic inputs into these systems and to examine the evolution of hydrothermal activity through time. The first 10-day portion of the cruise was funded by Nautilus Minerals in a collaborative research effort to examine the Manus Spreading Center and the Vienna Woods basalt-hosted hydrothermal vent systems. The second 32-day portion of the cruise, funded by the National Science Foundation (NSF), focused on the felsic-hosted hydrothermal systems of the PACMANUS (Papua New Guinea – Australia – Canada Manus) vents drilled by the Ocean Drilling Program (ODP) in 2000 and the nearby seafloor volcano vent systems of Desmos and SuSu Knolls. Nautilus Minerals generously funded the add-on use of ABE throughout the NSF program allowing for high resolution mapping to be completed on all the major vent sites within the eastern Manus Basin. A total of 30 ROV dives (497 operational hours) were completed collecting 198 vent sulfides, 83 altered substrate and 43 fresh lava samples along with 104 black, gray and clear fluid samples using gastight and major samplers. ABE successfully completed 14 high resolution bathymetric, CTD and magnetic field mapping dives covering a total of 364 line km of seafloor. We located and mapped in detail the Vienna Woods and nearby Tufar-2 and -3 vent areas on Manus Spreading Center documenting the strong tectonic control on the distribution of the vent systems and the presence of reduced magnetization i.e. “magnetic burnholes”, that help define the lateral extent of the vent fields. The Vienna Woods vent systems (273°-285°C) form treetrunk- like chimneys 5-15 m tall, that emit black to gray fluids with pH and compositions similar to other documented midocean ridge (MOR) systems like the East Pacific Rise. At PACMANUS, high-resolution mapping by ABE reveals a distinctive seafloor morphology associated with dacitic lava flows along with discrete magnetic burnholes associated with the active venting systems of Roman Ruins, Satanic Mills, Snowcap, Tsukushi and a new vigorous vent system discovered southeast of the Satanic Mills area named Fenway. Another vent field in its waning stages was also discovered ~8 km northeast of PACMANUS on the Northeast Pual Ridge. At PACMANUS, the 40 m diameter Fenway mound hosts outcrops of massive anhydrite on the seafloor beneath the sulfide chimneys, a rare occurrence as anhydrite is unstable at ambient seafloor conditions. Fenway is also boiling (356°C, 172 bar) with two-phase fluid producing a ”flashing” phenomenon when the Jason lights illuminated the vent orifices. The five PACMANUS vents (271° – 356°C) have ubiquitous low pH (2.3 to 2.8) relative to Vienna Woods and typical MOR fluids, presumably reflecting water-rock reaction with the felsic hosted lava, input of magmatic volatiles and the subsurface deposition of metal sulfides. We investigated two strongly magmatically influenced vent systems associated with seafloor volcanoes. Desmos is a breached caldera with white smokers (70°-115°C) that are highly acidic (pH 1 – 1.5) and sulfur lava flows. SuSu Knolls and the adjacent Suzette mound (Solwara-1 of Nautilus Minerals) were mapped in detail and sampled intensively. Hydrothermal activity at SuSu Knolls showed a remarkable range from boiling black smokers to white sulfur-rich fluids, native sulfur flows and massive anhydrite outcrops. Vent fluids from North Su (48° – 325°C) are 2 characterized by a measured pH of 0.87, more than an order of magnitude more acidic than any deep-sea vent fluid sampled to date. Many of the low pH fluids sampled at North Su and Desmos were actively precipitating native sulfur creating thick plumes of dense white smoke. In general, sampled fluids show a considerable range in pH and gas contents, sometimes within individual hydrothermal fields. The pronounced variability of fluid chemistry within 10’s to 100’s of m at North Su is probably unparalleled in systems studied to date. The most plausible explanation for the observed variability is that different fluid-rock reaction pathways are expressed in regimes of variable magmatic volatile input and extent of subsurface cooling. This hypothesis is supported by the distribution of alteration types at the seafloor, where the occurrence of advanced argillic alteration - that relates to interactions with acid-sulfate waters such as sampled at Desmos and North Su – is patchy and spatially confined to patches of active (Desmos, North Su) and past (Snowcap) venting of such fluids. In relationship to the ODP drilling results at PACMANUS we identified and sampled examples of advanced argillic rock alteration similar to that seen in the drill core. Good examples came from Snowcap and from the North Su pillar. We sampled highly clay-altered basement from just underneath extinct chimney complexes at two locations in the Satanic Mills hydrothermal field. Both samples have dense networks of sulfide veins and may represent the stockwork or feeder zone through which hydrothermal fluids rise up to the seafloor. These samples, in addition to the other altered rock types recovered, will provide useful stepping stones in bridging the knowledge gap between the extensive surface sampling now accomplished and the basement rocks recovered by ODP, where coring was almost nil shallower than 40 m subseafloor depth. Overall, the quality and quantity of solid and fluid samples that can be put in a direct geochemical context is remarkably high. This unique dataset encompasses a broad range of geological environments that includes hydrothermal activity in basalt-hosted oceanic style spreading centers to hydrothermal systems associated with arc-style volcanism. For the first time, alteration assemblages that are commonly observed in drillcore and outcrop on land have been observed in the aqueous environment responsible for their formation.NSF Grant – OCE0327448; NSF Grant – OCE042559

IVUS-based Fluid-structure Interaction Models for Novel Plaque Vulnerability Indices: A Study in Patients with Coronary Artery Disease

AbstractIt is believed that mechanical stresses play an important role in atherosclerotic plaque rupture process and may be used for better plaque vulnerability assessment and rupture risk predictions. IVUS data were acquired from 14 patients (11M, 3F, Mean age: 59,) for constructing 3D computational models combining fluid-structure interaction (FSI), cyclic bending due to cardiac contraction and patient-specific pressure loading to quantify mechanical conditions in the human coronary. The computational models were solved by a finite element package ADINA to obtain plaque wall stress (PWS), strain (PWSn) and flow shear stress (FSS) and investigate correlation between the mechanical conditions and morphological characteristics. For all 617 IVUS slices yielded from the 14 patients, plaque morphological features lipid percentage and min cap thickness were calculated for each slice, and three types of plaque morphology related indices: lipid index, cap index and morphological index (MPVI) were introduced as quantitative measures of plaque vulnerability. PWS, PWSn and FSS values at critical sites were denoted as critical plaque wall stress (CPWS), critical plaque wall strain (CPWSn) and critical flow shear stress (CFSS) for each slice, and a stress index was proposed based on the value of the CPWS. The conventional Pearson's correlation is used to analyze the correlation between each of the mechanical conditions and each plaque morphological feature indices. Our results suggest there is significant correlation between the CPWS and min cap thickness, cap index with the correlation coefficient r=-0.6570, r=0.8016 respectively, while the correlation between CPWS and lipid percentage and the lipid index are weaker (r=0.2209, r=0.2304) even though they are significantly correlated. The correlation results between CPWS and morphological index (r=0.7725, p-value<0.0001) showed there is a strong positive relationship between the mechanical stress and morphological features. For all 617 slices, the stress index has a 66.77% agreement with morphological index. More patient follow-up data and large-scale studies are needed to continue our investigations