Evaluation and Interventional Management of Cardiac Dysrhythmias.

This article focuses on the guideline-directed evaluation and management of cardiac dysrhythmias, particularly as they are important to the practice of a noncardiac surgeon. The focus is on atrial fibrillation (AF) as the most common arrhythmia encountered by surgeons. The authors discuss the importance of AF as a risk factor for perioperative morbidity and mortality. They pay particular attention to topics such as postoperative AF and options for its acute treatment and perioperative anticoagulation management. They discuss nonpharmacologic left atrial appendage management and nonpharmacologic AF management, including catheter-based therapy, surgical-based therapy, and hybrid therapies.

Designing and Testing of a System for Aerosolization and Recovery of Viable Porcine Reproductive and Respiratory Syndrome Virus (PRRSV): Theoretical and Engineering Considerations.

Porcine reproductive and respiratory syndrome virus (PRRSV) infections cause significant economic losses to swine producers every year. Aerosols containing infectious PRRSV are an important route of transmission, and proper treatment of air could mitigate the airborne spread of the virus within and between barns. Previous bioaerosol studies focused on the microbiology of PRRSV aerosols; thus, the current study addressed the engineering aspects of virus aerosolization and collection. Specific objectives were to (1) build and test a virus aerosolization system, (2) achieve a uniform and repeatable aerosol generation and collection throughout all replicates, (3) identify and minimize sources of variation, and (4) verify that the collection system (impingers) performed similarly. The system for virus aerosolization was built and tested (Obj. 1). The uniform airflow distribution was confirmed using a physical tracer (<12% relative standard deviation) for all treatments and sound engineering control of flow rates (Obj. 2). Theoretical uncertainty analyses and mass balance calculations showed <3% loss of air mass flow rate between the inlet and outlet (Obj. 3). A comparison of TCID50 values among impinger fluids showed no statistical difference between any two of the three trials (p-value = 0.148, 0.357, 0.846) (Obj. 4). These results showed that the readiness of the system for research on virus aerosolization and treatment (e.g., by ultraviolet light), as well as its potential use for research on other types of airborne pathogens and their mitigation on a laboratory scale.

Pilot-Scale Assessment of a Novel Farrowing Creep Area Supplementary Heat Source.

Pre-weaning morality (PWM) is attributed to a poor creep area microclimate and causes major economic and productivity losses for the US swine industry. Piglets need supplementary heat to overcome a high surface area to body weight ratio and minimal thermoregulation. A pilot-scale study was conducted to evaluate a semi-enclosed heated microclimate (SEHM) as a supplementary heat source for farrowing creep areas over six farrowing cycles (from January to July 2019) in two rooms with 24 farrowing stalls in each room. Six SEHMs (each SEHM covers two stalls) were randomly distributed to each room and compared to heat lamps (HLs) for productivity and electricity usage. Data from 113 (SEHM) and 101 litters (HL) showed no significant difference between treatments in average daily gain (p = 0.26), 252.4 ± 8.0 g hd-1 d-1 (SEHM) and 260.3 ± 8.1 g hd-1 d-1 (HL) and PWM (p = 0.08), 9.67% ± 0.82% (SEHM) and 12.04% ± 0.87% (HL). However, a significant difference (p = 0.02) was noted in the PWM attributed to over-lay mortalities, 4.05% ± 0.76% (SEHM) compared to 6.04% ± 0.78% (HL). The SEHM electricity averaged 3.25 kWh d-1 (2.91, 3.59 kWh d-1; 95% CI), which was significantly different (p < 0.01) from the HL equivalent (125 W bulb; 6 kWh d-1).

Angiographic Efficacy of the Atriclip Left Atrial Appendage Exclusion Device Placed by Minimally Invasive Thoracoscopic Approach.

OBJECTIVES: This study sought to assess long-term left atrial appendage (LAA) closure efficacy of the Atriclip applied via totally thoracoscopic (TT) approach with computed tomographic angiography. BACKGROUND: LAA closure is associated with a low risk for atrial fibrillation-related embolic stroke. The Atriclip exclusion device allows epicardial LAA closure, avoiding the need for post-operative oral anticoagulation. Previous data with Atriclip during open chest procedures show a high efficacy rate of closure >95%. METHODS: Three-dimensional volumetric 2-phase computed tomographic angiography ≥90 days post-implantation was independently assessed by chest radiology for complete LAA closure on all consented subjects identified retrospectively as having had a TT-placed Atriclip at Vanderbilt University Medical Center from June 13, 2011, to October 6, 2015. RESULTS: Complete LAA closure (defined by complete exclusion of the LAA with no exposed trabeculations, and clip within 1 cm from the left circumflex artery) was found in 61 of 65 subjects (93.9%). Four cases had incomplete closure (6.2%). Two clips were placed too distally, leaving a large stump with exposed trabeculae. Two clips failed to address a secondary LAA lobe. No major complications were associated with TT placement of the Atriclip. Follow-up over 183 patient-years revealed 1 stroke in a patient with complete LAA closure and no thrombus (hypertensive cerebrovascular accident). CONCLUSIONS: Angiographic LAA closure efficacy with a TT-placed Atriclip is high (93.9%). The clinical significance of a remnant stump is unknown. Confirmation of complete LAA occlusion should be made before cessation of systemic anticoagulation.

Hybrid Coronary Revascularization for the Treatment of Multivessel Coronary Artery Disease: A Multicenter Observational Study.

BACKGROUND: Hybrid coronary revascularization (HCR) combines minimally invasive surgical coronary artery bypass grafting of the left anterior descending artery with percutaneous coronary intervention (PCI) of non-left anterior descending vessels. HCR is increasingly used to treat multivessel coronary artery disease that includes stenoses in the proximal left anterior descending artery and at least 1 other vessel, but its effectiveness has not been rigorously evaluated. OBJECTIVES: This National Institutes of Health-funded, multicenter, observational study was conducted to explore the characteristics and outcomes of patients undergoing clinically indicated HCR and multivessel PCI for hybrid-eligible coronary artery disease, to inform the design of a confirmatory comparative effectiveness trial. METHODS: Over 18 months, 200 HCR and 98 multivessel PCI patients were enrolled at 11 sites. The primary outcome was major adverse cardiac and cerebrovascular events (MACCE) (i.e., death, stroke, myocardial infarction, repeat revascularization) within 12 months post-intervention. Cox proportional hazards models were used to model time to first MACCE event. Propensity scores were used to balance the groups. RESULTS: Mean age was 64.2 ± 11.5 years, 25.5% of patients were female, 38.6% were diabetic, and 4.7% had previous stroke. Thirty-eight percent had 3-vessel coronary artery disease, and the mean SYNTAX (Synergy Between PCI With Taxus and Cardiac Surgery) score was 19.7 ± 9.6. Adjusted for baseline risk, MACCE rates were similar between groups within 12 months post-intervention (hazard ratio [HR]: 1.063; p = 0.80) and during a median 17.6 months of follow-up (HR: 0.868; p = 0.53). CONCLUSIONS: These observational data from this first multicenter study of HCR suggest that there is no significant difference in MACCE rates over 12 months between patients treated with multivessel PCI or HCR, an emerging modality. A randomized trial with long-term outcomes is needed to definitively compare the effectiveness of these 2 revascularization strategies. (Hybrid Revascularization Observational Study; NCT01121263).

Summary of performance data for technologies to control gaseous, odor, and particulate emissions from livestock operations: Air management practices assessment tool (AMPAT).

The livestock and poultry production industry, regulatory agencies, and researchers lack a current, science-based guide and data base for evaluation of air quality mitigation technologies. Data collected from science-based review of mitigation technologies using practical, stakeholders-oriented evaluation criteria to identify knowledge gaps/needs and focuses for future research efforts on technologies and areas with the greatest impact potential is presented in the Literature Database tab on the air management practices tool (AMPAT). The AMPAT is web-based (available at www.agronext.iastate.edu/ampat) and provides an objective overview of mitigation practices best suited to address odor, gaseous, and particulate matter (PM) emissions at livestock operations. The data was compiled into Excel spreadsheets from a literature review of 265 papers was performed to (1) evaluate mitigation technologies performance for emissions of odor, volatile organic compounds (VOCs), ammonia (NH3), hydrogen sulfide (H2S), particulate matter (PM), and greenhouse gases (GHGs) and to (2) inform future research needs.

Staged versus Simultaneous Thoracoscopic Hybrid Ablation for Persistent Atrial Fibrillation Does Not Affect Time to Recurrence of Atrial Arrhythmia.

INTRODUCTION: Totally thoracoscopic (TT) epicardial ablation combined with endocardial catheter ablation is an emerging treatment for persistent AF. The effects of timing of the TT and endocardial portion on AT/AF recurrence are not known. METHODS: We retrospectively analyzed patients undergoing TT staged versus simultaneous hybrid AF ablation at our institution. Arrhythmia-free outcome was compared using time to recurrence (AF or AT greater than 30 seconds after a 3-month blanking period from endocardial ablation) at 12 months. All subjects had continuous ILR or PM monitoring. RESULTS: Eighty-three patients (52 same-day, 31 staged) underwent TT hybrid AF ablation. Recurrence was observed in 23 (29%) patients at a median time of 147 days (IQR 91,238). In univariate analysis, a staged approach significantly increased the likelihood of detecting incomplete PVI (OR 6 [95% CI 2-17] P = 0.001). However, only longstanding persistent AF (LSP-AF) status predicted recurrence (HR 4 [95% CI 1.4-12] P = 0.01). Neither a staged approach (HR 1.0 [95% CI 0.4-2.4] P = 0.9), nor detection of incomplete PVI (HR 0.9 [95% CI 0.4-2.3] P = 0.8) predicted time to first AF/AT recurrence. CONCLUSIONS: Staged hybrid ablation of AF significantly increases the likelihood of discovering incomplete PVI at the time of endocardial mapping versus a same-day procedure. However, the staged approach did not improve time to first AT/AF recurrence.

Improved quantification of livestock associated odorous volatile organic compounds in a standard flow-through system using solid-phase microextraction and gas chromatography-mass spectrometry.

Aerial emissions of odorous volatile organic compounds (VOCs) are an important nuisance factor from livestock production systems. Reliable air sampling and analysis methods are needed to develop and test odor mitigation technologies. Quantification of VOCs responsible for livestock odor remains an analytical challenge due to physicochemical properties of VOCs and the requirement for low detection thresholds. A new air sampling and analysis method was developed for testing of odor/VOCs mitigation in simulated livestock emissions system. A flow-through standard gas generating system simulating odorous VOCs in livestock barn emissions was built on laboratory scale and tested to continuously generate ten odorous VOCs commonly defining livestock odor. Standard VOCs included sulfur VOCs (S-VOCs), volatile fatty acids (VFAs), and p-cresol. Solid-phase microextraction (SPME) was optimized for sampling of diluted odorous gas mixtures in the moving air followed by gas chromatography-mass spectrometry (GC-MS) analysis. CAR/PDMS 85µm fiber was shown to have the best sensitivity for the target odorous VOCs. A practical 5-min sampling time was selected to ensure optimal extraction of VFAs and p-cresol, as well as minimum displacement of S-VOCs. Method detection limits ranged from 0.39 to 2.64ppbv for S-VOCs, 0.23 to 0.77ppbv for VFAs, and 0.31ppbv for p-cresol. The method developed was applied to quantify VOCs and odorous VOC mitigation with UV light treatment. The measured concentrations ranged from 20.1 to 815ppbv for S-VOCs, 10.3 to 315ppbv for VFAs, and 4.73 to 417ppbv for p-cresol. Relative standard deviations between replicates ranged from 0.67% to 12.9%, 0.50% to 11.4%, 0.83% to 5.14% for S-VOCs, VFAs, and p-cresol, respectively. This research shows that a simple manual SPME sampler could be used successfully for quantification of important classes of odorous VOCs at concentrations relevant for real aerial emissions from livestock operations.

Hypertension is associated with preamyloid oligomers in human atrium: a missing link in atrial pathophysiology?

BACKGROUND: Increasing evidence indicates that proteotoxicity plays a pathophysiologic role in experimental and human cardiomyopathy. In organ-specific amyloidoses, soluble protein oligomers are the primary cytotoxic species in the process of protein aggregation. While isolated atrial amyloidosis can develop with aging, the presence of preamyloid oligomers (PAOs) in atrial tissue has not been previously investigated. METHODS AND RESULTS: Atrial samples were collected during elective cardiac surgery in patients without a history of atrial arrhythmias, congestive heart failure, cardiomyopathy, or amyloidosis. Immunohistochemistry was performed for PAOs using a conformation-specific antibody, as well as for candidate proteins identified previously in isolated atrial amyloidosis. Using a myocardium-specific marker, the fraction of myocardium colocalizing with PAOs (PAO burden) was quantified (green/red ratio). Atrial samples were obtained from 92 patients, with a mean age of 61.7±13.8 years. Most patients (62%) were male, 23% had diabetes, 72% had hypertension, and 42% had coronary artery disease. A majority (n=62) underwent aortic valve replacement, with fewer undergoing coronary artery bypass grafting (n=34) or mitral valve replacement/repair (n=24). Immunostaining detected intracellular PAOs in a majority of atrial samples, with a heterogeneous distribution throughout the myocardium. Mean green/red ratio value for the samples was 0.11±0.1 (range 0.03 to 0.77), with a value ≥0.05 in 74 patients. Atrial natriuretic peptide colocalized with PAOs in myocardium, whereas transthyretin was located in the interstitium. Adjusting for multiple covariates, PAO burden was independently associated with the presence of hypertension. CONCLUSION: PAOs are frequently detected in human atrium, where their presence is associated with clinical hypertension.

Quantitative Imaging of Preamyloid Oligomers, a Novel Structural Abnormality, in Human Atrial Samples.

Abnormalities in atrial myocardium increase the likelihood of arrhythmias, including atrial fibrillation (AF). The deposition of misfolded protein, or amyloidosis, plays an important role in the pathophysiology of many diseases, including human cardiomyopathies. We have shown that genes implicated in amyloidosis are activated in a cellular model of AF, with the development of preamyloid oligomers (PAOs). PAOs are intermediates in the formation of amyloid fibrils, and they are now recognized to be the cytotoxic species during amyloidosis. To investigate the presence of PAOs in human atrium, we developed a microscopic imaging-based protocol to enable robust and reproducible quantitative analysis of PAO burden in atrial samples harvested at the time of elective cardiac surgery. Using PAO- and myocardial-specific antibodies, we found that PAO distribution was typically heterogeneous within a myocardial sample. Rigorous imaging and analysis protocols were developed to quantify the relative area of myocardium containing PAOs, termed the Green/Red ratio (G/R), for a given sample. Using these methods, reproducible G/R values were obtained when different sections of a sample were independently processed, imaged, and analyzed by different investigators. This robust technique will enable studies to investigate the role of this novel structural abnormality in the pathophysiology of and arrhythmia generation in human atrial tissue.

High-risk lead removal by planned sequential transvenous laser extraction and minimally invasive right thoracotomy.

INTRODUCTION: Transvenous pacemaker or implantable cardioverter defibrillator (ICD) lead extraction via mechanical or excimer laser sheath is typically safe and effective. Longer duration from implant, presence of large vegetations or thrombi, fractured leads, and prior failed extraction are risk factors predicting higher complication rates or incomplete or failed lead removal. Techniques developed for minimally invasive valve surgery were used in conjunction with laser extraction to refine a "hybrid" technique for lead extraction. We assessed the outcomes of high-risk lead extraction using this hybrid lead extraction technique. METHODS AND RESULTS: Retrospective assessment of clinical parameters and procedural outcomes in patients undergoing planned hybrid lead extraction from February 2008 to September 2012 was performed. We report 8 cases of hybrid lead extraction performed at our institution. We extracted 21 leads with average lead age of 13.8 years since implant. All leads were removed with complete clinical and radiographic success. There were no intraprocedure complications. One patient died of continued sepsis and 1 other had symptoms consistent with pulmonary embolism. CONCLUSIONS: Hybrid lead extraction using this technique is a safe and effective approach for removal of high-risk chronic pacemaker or ICD leads. This method extends the range of approachable leads resulting in complete removal without median sternotomy. Hybrid lead extraction can be scheduled electively facilitating complete lead removal with a low complication rate and short postoperative recovery time, mitigating the risks inherent in midline sternotomy or emergent cardiac surgical rescue.

A method to quantify infectious airborne pathogens at concentrations below the threshold of quantification by culture.

In aerobiology, dose-response studies are used to estimate the risk of infection to a susceptible host presented by exposure to a specific dose of an airborne pathogen. In the research setting, host- and pathogen-specific factors that affect the dose-response continuum can be accounted for by experimental design, but the requirement to precisely determine the dose of infectious pathogen to which the host was exposed is often challenging. By definition, quantification of viable airborne pathogens is based on the culture of micro-organisms, but some airborne pathogens are transmissible at concentrations below the threshold of quantification by culture. In this paper we present an approach to the calculation of exposure dose at microbiologically unquantifiable levels using an application of the "continuous-stirred tank reactor (CSTR) model" and the validation of this approach using rhodamine B dye as a surrogate for aerosolized microbial pathogens in a dynamic aerosol toroid (DAT).

En aérobiologie, les études dose-réponse sont utilisées pour estimer le risque d'infection que représente pour un hôte susceptible l'exposition à une dose spécifique d'un agent pathogène en suspension dans l'air. Dans un environnement de recherche, les facteurs spécifiques à l'hôte et à l'agent qui affectent le continuum dose-réponse peuvent être tenus pour compte dans le design expérimental, mais l'obligation de déterminer précisément la dose d'agent pathogène à laquelle l'hôte a été exposée représente souvent un défi. Par définition, la quantification des agents pathogènes viables en suspension dans l'air est basée sur la culture des microorganismes, mais certains agents pathogènes aériens sont transmissibles à des concentrations inférieures au seuil de quantification par culture. Dans cet article nous présentons une approche pour le calcul de la dose d'exposition à des niveaux non-quantifiables microbiologiquement en utilisant une application du modèle de réaction en réservoir avec agitation continue (CSTR) et la validation de cette approche en utilisant le colorant rhodamine B comme substitut à des agents pathogènes microbiens mis en aérosol dans un tore dynamique (DAT).(Traduit par Docteur Serge Messier).

Angiotensin-converting enzyme inhibition or mineralocorticoid receptor blockade do not affect prevalence of atrial fibrillation in patients undergoing cardiac surgery.

OBJECTIVE: This study tested the hypothesis that interruption of the renin-angiotensin system with either an angiotensin-converting enzyme inhibitor or a mineralocorticoid receptor antagonist will decrease the prevalence of atrial fibrillation after cardiac surgery. DESIGN: Randomized double-blind placebo-controlled study. SETTING: University-affiliated hospitals. PATIENTS: Four hundred forty-five adult patients in normal sinus rhythm undergoing elective cardiac surgery. INTERVENTIONS: One week to 4 days prior to surgery, patients were randomized to treatment with placebo, ramipril (2.5 mg the first 3 days followed by 5 mg/day, with the dose reduced to 2.5 mg/day on the first postoperative day only), or spironolactone (25 mg/day). MEASUREMENTS: The primary endpoint was the occurrence of electrocardiographically confirmed postoperative atrial fibrillation. Secondary endpoints included acute renal failure, hyperkalemia, the prevalence of hypotension, length of hospital stay, stroke, and death. MAIN RESULTS: The prevalence of atrial fibrillation was 27.2% in the placebo group, 27.8% in the ramipril group, and 25.9% in the spironolactone group (p=.95). Patients in the ramipril (0.7%) or spironolactone (0.7%) group were less likely to develop acute renal failure than those randomized to placebo (5.4%, p=.006). Patients in the placebo group tended to be hospitalized longer than those in the ramipril or spironolactone group (6.8±8.2 days vs. 5.7±3.2 days and 5.8±3.4 days, respectively, p=.08 for the comparison of placebo vs. the active treatment groups using log-rank test). Compared with patients in the placebo group, patients in the spironolactone group were extubated sooner after surgery (576.4±761.5 mins vs. 1091.3±3067.3 mins, p=.04). CONCLUSIONS: Neither angiotensin-converting enzyme inhibition nor mineralocorticoid receptor blockade decreased the primary outcome of postoperative atrial fibrillation. Treatment with an angiotensin-converting enzyme inhibitor or mineralocorticoid receptor antagonist was associated with decreased acute renal failure. Spironolactone use was also associated with a shorter duration of mechanical ventilation after surgery.

Effect of temperature and relative humidity on ultraviolet (UV 254) inactivation of airborne porcine respiratory and reproductive syndrome virus.

The objective of this research was to estimate the effects of temperature and relative humidity on the inactivation of airborne porcine reproductive and respiratory syndrome (PRRS) virus by ultraviolet light (UV(254)). Aerosols of PRRS virus were exposed to one of four doses of UV(254) under nine combinations of temperature (n=3) and relative humidity (n=3). Inactivation constants (k), defined as the absolute value of the slope of the linear relationship between the survival fraction of the microbial population and the UV(254) exposure dose, were estimated using the random coefficient model. The associated UV(254) half-life dose for each combination of environmental factors was determined as (log(10)2/k) and expressed as UV(254) mJ per unit volume. The effects of UV(254) dose, temperature, and relative humidity were all statistically significant, as were the interactions between UV(254) dose × temperature and UV(254) dose × relative humidity. PRRS virus was more susceptible to ultraviolet as temperature decreased; most susceptible to ultraviolet inactivation at relative humidity between 25% and 79%, less susceptible at relative humidity ≤ 24%, and least susceptible at ≥ 80% relative humidity. The current study allows for calculating the dose of UV(254) required to inactivate airborne PRRS virus under various laboratory and field conditions using the inactivation constants and UV(254) half-life doses reported therein.

Benefits of ambulatory axillary intra-aortic balloon pump for circulatory support as bridge to heart transplant.

OBJECTIVE: Axillary intra-aortic balloon pump therapy has been described as a bridge to transplant. Advantages over femoral intra-aortic balloon pump therapy include reduced incidence of infection and enhanced patient mobility. We identified the patients who would benefit most from this therapy while awaiting heart transplantation. METHODS: We conducted a single-center, retrospective observational study to evaluate outcomes from axillary intra-aortic balloon pump therapy. These included hemodynamic parameters, duration of support, and success in bridging to transplant. We selected patients on the basis of history of sternotomy, elevated panel-reactive antibody, and small body habitus. Patients were made to ambulate aggressively beginning on postoperative day 1. RESULTS: Between September 2007 and September 2010, 18 patients underwent axillary intra-aortic balloon pump therapy. All patients had the devices placed through the left axillary artery with a Hemashield side graft (Boston Scientific, Natick, Mass). Before axillary placement, patients underwent femoral placement to demonstrate hemodynamic benefit. Duration of support ranged from 5 to 63 days (median = 19 days). There was marked improvement in ambulatory potential and hemodynamic parameters, with minimal blood transfusion requirements. There were no device-related infections. Some 72% of the patients (13/18) were successfully bridged to transplantation. CONCLUSIONS: Axillary intra-aortic balloon pump therapy provides excellent support for selected patients as a bridge to transplant. The majority of the patients were successfully bridged to transplant and discharged. Although this therapy has been described in previous studies, this is the largest series to incorporate a regimen of aggressive ambulation with daily measurements of distances walked.

Current status of hybrid coronary revascularization.

Hybrid coronary revascularization combines coronary artery bypass surgery with percutaneous coronary intervention techniques to treat coronary artery disease. The potential benefits of such a technique are to offer the patients the best available treatments for coronary artery disease while minimizing the risks of the surgery. Hybrid coronary revascularization has resulted in the establishment of new 'hybrid operating suites', which incorporate and integrate the capabilities of a cardiac surgery operating room with that of an interventional cardiology laboratory. Hybrid coronary revascularization has greatly augmented teamwork and cooperation between both fields and has demonstrated encouraging as well as good initial outcomes.

Minimally invasive mitral valve surgery expands the surgical options for high-risks patients.

BACKGROUND: A simplified minimally invasive mitral valve surgery (MIMVS) approach avoiding cross-clamping and cardioplegic myocardial arrest using a small (5 cm) right antero-lateral incision was developed. We hypothesized that, in high-risk patients and in patients with prior sternotomy, this approach would yield superior results compared to those predicted by the Society of Thoracic Surgeons (STS) algorithm for standard median sternotomy mitral valve surgery. METHODS: Five hundred and four consecutive patients (249 males/255 females), median age 65 years (range 20-92 years) underwent MIMVS between 1/06 and 8/09. Median preoperative New York Heart Association function class was 3 (range 1-4). Eighty-two (16%) patients had an ejection fraction ≤35%. Forty-seven (9%) had a STS predicted mortality ≥10%. Under cold fibrillatory arrest (median temperature 28°C) without aortic cross-clamp, mitral valve repair (224/504, 44%) or replacement (280/504, 56%) was performed. RESULTS: Thirty-day mortality for the entire cohort was 2.2% (11/504). In patients with a STS predicted mortality ≥ 10% (range 10%-67%), the observed 30-day mortality was 4% (2/47), lower than the mean STS predicted mortality of 20%. Morbidity in this high-risk group was equally low: 1 of 47 (2%) patients underwent reexploration for bleeding, 1 of 47 (2%) patients suffered a permanent neurologic deficit, none had wound infection. The median length of stay was 8 days (range 1-68 days). CONCLUSIONS: This study demonstrates that MIMVS without aortic cross-clamp is reproducible with low mortality and morbidity rates. This approach expands the surgical options for high-risk patients and yields to superior results than the conventional median sternotomy approach.

Median infectious dose (ID50) of porcine reproductive and respiratory syndrome virus isolate MN-184 via aerosol exposure.

The median infectious dose (ID(50)) of porcine reproductive and respiratory syndrome (PRRS) virus isolate MN-184 was determined for aerosol exposure. In 7 replicates, 3-week-old pigs (n=58) respired 10l of airborne PRRS virus from a dynamic aerosol toroid (DAT) maintained at -4°C. Thereafter, pigs were housed in isolation and monitored for evidence of infection. Infection occurred at virus concentrations too low to quantify by microinfectivity assays. Therefore, exposure dose was determined using two indirect methods ("calculated" and "theoretical"). "Calculated" virus dose was derived from the concentration of rhodamine B monitored over the exposure sequence. "Theoretical" virus dose was based on the continuous stirred-tank reactor model. The ID(50) estimate was modeled on the proportion of pigs that became infected using the probit and logit link functions for both "calculated" and "theoretical" exposure doses. Based on "calculated" doses, the probit and logit ID(50) estimates were 1 × 10(-0.13)TCID(50) and 1 × 10(-0.14)TCID(50), respectively. Based on "theoretical" doses, the probit and logit ID(50) were 1 × 10(0.26)TCID(50) and 1 × 10(0.24)TCID(50), respectively. For each point estimate, the 95% confidence interval included the other three point estimates. The results indicated that MN-184 was far more infectious than PRRS virus isolate VR-2332, the only other PRRS virus isolate for which ID(50) has been estimated for airborne exposure. Since aerosol ID(50) estimates are available for only these two isolates, it is uncertain whether one or both of these isolates represent the normal range of PRRS virus infectivity by this route.

Results of completion arteriography after minimally invasive off-pump coronary artery bypass.

BACKGROUND: The benefits of a minimally invasive approach to off-pump coronary artery bypass remain controversial. The value of completion arteriography in validating this technique has not been investigated. METHODS: From April 2007 to October 2009, fifty-six patients underwent isolated minimally invasive coronary artery bypass grafting through a left thoracotomy without cardiopulmonary bypass. Forty-three of these patients underwent completion arteriography. RESULTS: Sixty-five grafts were performed in these 56 patients, (average, 1.2 grafts per patient; range, 1 to 3). Forty-eight grafts were studied in the 43 patients undergoing completion arteriography. There were 4 findings on arteriogram leading to further immediate intervention (8.3%). These included 3 grafts with anastomotic stenoses or spasm requiring stent placement, and 1 patient who had limited dissection in the left internal mammary artery graft and underwent placement of an additional vein graft. These findings were independent of electrocardiographic changes or hemodynamic instability. The remainder of the studies showed no significant abnormalities. There were no deaths. One patient who did not have a completion arteriogram suffered a postoperative myocardial infarction requiring stent placement for anastomotic stenosis. Patients were discharged home an average of 6.8 days postoperatively. There were no instances of renal dysfunction postoperatively attributable to catheterization. CONCLUSIONS: Minimally invasive coronary artery bypass is safe and effective. Findings of completion arteriography occasionally reveal previously under-recognized findings that, if corrected in a timely fashion, could potentially impact graft patency and clinical outcomes. Our experience validates this minimally invasive technique.