Evaluation of the Efficacy of a Novel Dermatotomy Device for Central Venous Cannulation.

OBJECTIVE: To test the effectiveness of a novel wire-guided scalpel (Guideblade) to create a precise dermatotomy incision for central venous catheter (CVC) insertion. DESIGN: Prospective, nonrandomized interventional study. SETTING: Stanford University, single-center teaching hospital. PARTICIPANTS: Cardiac and vascular surgical patients (n = 100) with planned CVC insertion for operation. INTERVENTIONS: A wire-guided scalpel was used during CVC insertion. RESULTS: A total of 188 CVCs were performed successfully with a wire-guided scalpel without the need for additional equipment in 100 patients, and 94% of CVCs were accomplished with only a single dermatotomy attempt. "No bleeding" or "minimal bleeding" at the insertion site was observed in 90% of patients 30 minutes after insertion and 80.7% at the conclusion of surgery. CONCLUSION: The wire-guided scalpel was effective in performing dermatotomy for CVC with a 100% success rate and a very high first-attempt rate. The wire-guided scalpel may decrease bleeding at the CVC insertion site.

Strain estimation in aortic roots from 4D echocardiographic images using medial modeling and deformable registration.

Even though the central role of mechanics in the cardiovascular system is widely recognized, estimating mechanical deformation and strains in-vivo remains an ongoing practical challenge. Herein, we present a semi-automated framework to estimate strains from four-dimensional (4D) echocardiographic images and apply it to the aortic roots of patients with normal trileaflet aortic valves (TAV) and congenital bicuspid aortic valves (BAV). The method is based on fully nonlinear shell-based kinematics, which divides the strains into in-plane (shear and dilatational) and out-of-plane components. The results indicate that, even for size-matched non-aneurysmal aortic roots, BAV patients experience larger regional shear strains in their aortic roots. This elevated strains might be a contributing factor to the higher risk of aneurysm development in BAV patients. The proposed framework is openly available and applicable to any tubular structures.

Dynamic Volumetric Assessment of the Aortic Root: The Influence of Bicuspid Aortic Valve Competence.

BACKGROUND: Aortic root evaluation is conventionally based on 2-dimensional measurements at a single phase of the cardiac cycle. This work presents an image analysis method for assessing dynamic 3-dimensional changes in the aortic root of minimally calcified bicuspid aortic valves (BAVs) with and without moderate to severe aortic regurgitation. METHODS: The aortic root was segmented over the full cardiac cycle in 3-dimensional transesophageal echocardiographic images acquired from 19 patients with minimally calcified BAVs and from 16 patients with physiologically normal tricuspid aortic valves (TAVs). The size and dynamics of the aortic root were assessed using the following image-derived measurements: absolute mean root volume and mean area at the level of the ventriculoaortic junction, sinuses of Valsalva, and sinotubular junction, as well as normalized root volume change and normalized area change of the ventriculoaortic junction, sinuses of Valsalva, and sinotubular junction over the cardiac cycle. RESULTS: Normalized volume change over the cardiac cycle was significantly greater in BAV roots with moderate to severe regurgitation than in normal TAV roots and in BAV roots with no or mild regurgitation. Aortic root dynamics were most significantly different at the mid-level of the sinuses of Valsalva in BAVs with moderate to severe regurgitation than in competent TAVs and BAVs. CONCLUSIONS: Echocardiographic reconstruction of the aortic root demonstrates significant differences in dynamics of BAV roots with moderate to severe regurgitation relative to physiologically normal TAVs and competent BAVs. This finding may have implications for risk of future dilatation, dissection, or rupture, which warrant further investigation.

The Economic Consequences of Cardiac Surgery Associated Acute Renal Dysfunction After Heart Surgery.

The Society of Thoracic Surgeons definition of acute renal failure requires a 3-fold rise in creatinine, creatinine > 4 mg/dL (with at least 0.5mg/dL rise from preoperative value), or new hemodialysis requirement. This definition does not capture the incidence, clinical impact, and economic burden of lesser degrees of acute renal dysfunction. A retrospective cohort study using discharge data from 650 hospitals was extracted from the Premier administrative database (2010-2014) for index cardiac cases (isolated coronary artery bypass grafting, isolated valve, and coronary artery bypass grafting-valve). We documented acute renal dysfunction through International Classification of Diseases (ICD) 9-CM codes and hospital charges, excluding those patients with pre-existing renal dysfunction. The incidence, length of stay , and total hospital costs associated with renal dysfunction for each of the index procedures were captured. The results reported are unadjusted for demographic and clinical factors. A total of 200,471 procedures were available for analysis in the database. The mean age was 66 years, 68.2% were male and 74% were white. Based on ICD 9-CM codes and hospital charges for these cases, 27,216 (13.6%) patients had some level of renal dysfunction. In addition to increase in length of stay, patients who developed renal dysfunction had an associated 57-85% increase in total cost of hospitalization. The incidence of renal dysfunction in this study is higher than reported previously. The Society of Thoracic Surgeons definition of renal failure captures only severe disease and may miss lesser degrees of dysfunction, which nonetheless have an impact on patient outcome and costs.

The Penn Classification Predicts Hospital Mortality in Acute Stanford Type A and Type B Aortic Dissections.

OBJECTIVES: Mortality in acute aortic dissection varies depending on anatomic location, extent, and associated complications. The Stanford classification guides surgical versus medical management. The Penn classification stratifies mortality risk in patients with Stanford type A aortic dissections undergoing surgery. The objective of the present study was to determine whether the Penn classification can predict hospital mortality in patients with acute Stanford type A and type B aortic dissections undergoing surgical or medical management. DESIGN: Retrospective, observational study. SETTING: Tertiary care, university hospital. PARTICIPANTS: Patients with acute aortic dissection between January 2008 and December 2017. INTERVENTIONS: Examination of hospital mortality after surgical or medical management. MEASUREMENTS AND MAIN RESULTS: Three hundred fifty-two patients had confirmed dissections (186 type A, 166 type B). The overall mortality was 18.8% for type A and 13.3% for type B. Penn class A patients with type A or type B dissections undergoing surgical repair had the lowest mortality (both 3.1%). Penn class B, C, or B+C patients with type A dissections and Penn class B+C patients with type B dissections undergoing medical management had the greatest incidence of mortality (50.0%-57.1%). All others had intermediate mortality (6.7%-39.3%). Logistic regression analysis demonstrated that Penn class B, C, and B+C patients had a greater odds of mortality and predicted mortality than did Penn class A patients. CONCLUSIONS: The Penn classification predicts hospital mortality in patients with acute Stanford type A or type B aortic dissections undergoing surgical or medical management. Early endovascular repair may confer lower risk of mortality in patients with type B dissections presenting without ischemia.

The "Ice Age" in Cardiac Surgery: Evolution of the "Siberian" Method of Brain Protection During Deep Hypothermic Perfusionless Circulatory Arrest.

Deep hypothermic perfusionless circulatory arrest was the first practical neuroprotective technique used for open-heart surgery. It was refined at the Novosibirsk Medical Research Center in Siberia and was actively used from the mid-1950s until 2001.This review describes the development of this technique and its contribution to our understanding of the dynamic changes in human physiology during induced hypothermia for circulatory arrest without extracorporeal perfusion. Deep hypothermic perfusionless circulatory arrest was an important stepping stone in the development of modern approaches in neuroprotection and monitoring during cardiac surgery.

Spatiotemporal Segmentation and Modeling of the Mitral Valve in Real-Time 3D Echocardiographic Images.

Transesophageal echocardiography is the primary imaging modality for preoperative assessment of mitral valves with ischemic mitral regurgitation (IMR). While there are well known echocardiographic insights into the 3D morphology of mitral valves with IMR, such as annular dilation and leaflet tethering, less is understood about how quantification of valve dynamics can inform surgical treatment of IMR or predict short-term recurrence of the disease. As a step towards filling this knowledge gap, we present a novel framework for 4D segmentation and geometric modeling of the mitral valve in real-time 3D echocardiography (rt-3DE). The framework integrates multi-atlas label fusion and template-based medial modeling to generate quantitatively descriptive models of valve dynamics. The novelty of this work is that temporal consistency in the rt-3DE segmentations is enforced during both the segmentation and modeling stages with the use of groupwise label fusion and Kalman filtering. The algorithm is evaluated on rt-3DE data series from 10 patients: five with normal mitral valve morphology and five with severe IMR. In these 10 data series that total 207 individual 3DE images, each 3DE segmentation is validated against manual tracing and temporal consistency between segmentations is demonstrated. The ultimate goal is to generate accurate and consistent representations of valve dynamics that can both visually and quantitatively provide insight into normal and pathological valve function.

Assessment of Left Ventricular Dimensions by Transoesophageal Echocardiography in Patients During Coronary Artery Bypass Surgery.

OBJECTIVE: Normative values of left ventricular (LV) end-diastolic area and diameter (EDA and EDD) for intraoperative transoesophageal echocardiography (TEE) have not been established. We aimed to define the ranges of LV EDA and EDD for intraoperative TEE examinations in patients undergoing coronary artery bypass graft (CABG) surgery. METHODS: A MEDLINE search for studies reporting LV EDA and EDD in CABG patients was performed. Individual-level dataset from 333 anaesthetised and mechanically ventilated patients with preserved LV function (study population) were received from 8 studies. EDA and calculated EDD values in the study population were compared with summary mean EDD values obtained by transthoracic echocardiography (TTE) in 2 studies of 500 awake patients with coronary artery disease (CAD). Further, the influence of prespecified factors on EDD was evaluated through a multivariate regression model. RESULTS: LV EDA and EDD values measured by TEE in anaesthetised CABG patients were 16.7±4.7 cm2 and 4.6±0.6 cm, respectively. EDD values measured by TEE in anaesthetised patients were 10% to 13% less those measured by TTE in 2 studies of awake patients (p<0.001). Body surface area, age and fractional area change but not sex were factors that affected LV EDD. CONCLUSION: LV EDD values measured by intraoperative TEE in anaesthetised and mechanically ventilated CABG patients were 10% to 13% less than those measured by TTE in awake CAD patients. This finding indicates that independent normative values specific for intraoperative TEE should be established for guiding intraoperative clinical decisions.

Modeling the Myxomatous Mitral Valve With Three-Dimensional Echocardiography.

BACKGROUND: Degenerative mitral valve disease is associated with variable and complex defects in valve morphology. Three-dimensional echocardiography (3DE) has shown promise in aiding preoperative planning for patients with this disease but to date has not been as transformative as initially predicted. The clinical usefulness of 3DE has been limited by the laborious methods currently required to extract quantitative data from the images. METHODS: To maximize the utility of 3DE for preoperative valve evaluation, this work describes an automated 3DE image analysis method for generating models of the mitral valve that are well suited for both qualitative and quantitative assessment. The method is unique in that it captures detailed alterations in mitral leaflet and annular morphology and produces image-derived models with locally varying leaflet thickness. The method is evaluated on midsystolic transesophageal 3DE images acquired from 22 subjects with myxomatous degeneration and from 22 subjects with normal mitral valve morphology. RESULTS: Relative to manual image analysis, the automated method accurately represents both normal and complex leaflet geometries with a mean boundary displacement error on the order of one image voxel. A detailed quantitative analysis of the valves is presented and reveals statistically significant differences between normal and myxomatous valves with respect to numerous aspects of annular and leaflet geometry. CONCLUSIONS: This work demonstrates a successful methodology for the relatively rapid quantitative description of the complex mitral valve distortions associated with myxomatous degeneration. The methodology has the potential to significantly improve surgical planning for patients with complex mitral valve disease.

The value of preoperative 3-dimensional over 2-dimensional valve analysis in predicting recurrent ischemic mitral regurgitation after mitral annuloplasty.

OBJECTIVES: Repair for ischemic mitral regurgitation with undersized annuloplasty is characterized by high recurrence rates. We sought to determine the value of pre-repair 3-dimensional echocardiography over 2-dimensional echocardiography in predicting recurrence at 6 months. METHODS: Intraoperative transesophageal 2-dimensional echocardiography and 3-dimensional echocardiography were performed in 50 patients undergoing undersized annuloplasty for ischemic mitral regurgitation. Two-dimensional echocardiography annular diameter and tethering parameters were measured in the apical 2- and 4-chamber views. A customized protocol was used to assess 3-dimensional annular geometry and regional leaflet tethering. Recurrence (grade ≥2) was assessed with 2-dimensional transthoracic echocardiography at 6 months. RESULTS: Preoperative 2- and 3-dimensional annular geometry were similar in all patients with ischemic mitral regurgitation. Preoperative 2- and 3-dimensional leaflet tethering were significantly higher in patients with recurrence (n = 13) when compared with patients without recurrence (n = 37). Multivariate logistic regression revealed preoperative 2-dimensional echocardiography posterior tethering angle as an independent predictor of recurrence with an optimal cutoff value of 32.0° (area under the curve, 0.81; 95% confidence interval, 0.68-0.95; P = .002) and preoperative 3-dimensional echocardiography P3 tethering angle as an independent predictor of recurrence with an optimal cutoff value of 29.9° (area under the curve, 0.92; 95% confidence interval, 0.84-1.00; P < .001). The predictive value of the 3-dimensional geometric multivariate model can be augmented by adding basal aneurysm/dyskinesis (area under the curve, 0.94; 95% confidence interval, 0.87-1.00; P < .001). CONCLUSIONS: Preoperative 3-dimensional echocardiography P3 tethering angle is a stronger predictor of ischemic mitral regurgitation recurrence after annuloplasty than preoperative 2-dimensional echocardiography posterior tethering angle, which is highly influenced by viewing plane. In patients with a preoperative P3 tethering angle of 29.9° or larger (especially when combined with basal aneurysm/dyskinesis), chordal-sparing valve replacement should be strongly considered.

Sodium bicarbonate use and the risk of hypernatremia in thoracic aortic surgical patients with metabolic acidosis following deep hypothermic circulatory arrest.

OBJECTIVE: Metabolic acidosis after deep hypothermic circulatory arrest (DHCA) for thoracic aortic operations is commonly managed with sodium bicarbonate (NaHCO 3 ). The purpose of this study was to determine the relationships between total NaHCO 3 dose and the severity of metabolic acidosis, duration of mechanical ventilation, duration of vasoactive infusions, and Intensive Care Unit (ICU) or hospital length of stay (LOS). METHODS: In a single center, retrospective study, 87 consecutive elective thoracic aortic operations utilizing DHCA, were studied. Linear regression analysis was used to test for the relationships between the total NaHCO 3 dose administered through postoperative day 2, clinical variables, arterial blood gas values, and short-term clinical outcomes. RESULTS: Seventy-five patients (86%) received NaHCO 3 . Total NaHCO 3 dose averaged 136 ± 112 mEq (range: 0.0-535 mEq) per patient. Total NaHCO 3 dose correlated with minimum pH (r = 0.41, P < 0.0001), minimum serum bicarbonate (r = -0.40, P < 0.001), maximum serum lactate (r = 0.46, P = 0.007), duration of metabolic acidosis (r = 0.33, P = 0.002), and maximum serum sodium concentrations (r = 0.29, P = 0.007). Postoperative hypernatremia was present in 67% of patients and peaked at 12 h following DHCA. Eight percent of patients had a serum sodium ≥ 150 mEq/L. Total NaHCO 3 dose did not correlate with anion gap, serum chloride, not the duration of mechanical ventilator support, vasoactive infusions, ICU or hospital LOS. CONCLUSION: Routine administration of NaHCO 3 was common for the management of metabolic acidosis after DHCA. Total dose of NaHCO 3 was a function of the severity and duration of metabolic acidosis. NaHCO 3 administration contributed to postoperative hypernatremia that was often severe. The total NaHCO 3 dose administered was unrelated to short-term clinical outcomes.

Preoperative Three-Dimensional Valve Analysis Predicts Recurrent Ischemic Mitral Regurgitation After Mitral Annuloplasty.

BACKGROUND: Valve repair for ischemic mitral regurgitation (IMR) with undersized annuloplasty rings is characterized by high IMR recurrence rates. Patient-specific preoperative imaging-based risk stratification for recurrent IMR would optimize results. We sought to determine if prerepair three-dimensional (3D) echocardiography combined with a novel valve-modeling algorithm would be predictive of IMR recurrence 6 months after repair. METHODS: Intraoperative transesophageal real-time 3D echocardiography was performed in 50 patients undergoing undersized ring annuloplasty for IMR and in 21 patients with normal mitral valves. A customized image analysis protocol was used to assess 3D annular geometry and regional leaflet tethering. IMR recurrence (≥ grade 2) was assessed with two-dimensional transthoracic echocardiography 6 months after repair. RESULTS: Preoperative annular geometry was similar in all IMR patients, and preoperative leaflet tethering was significantly higher in patients with recurrent IMR (n=13) than in patients in whom IMR did not recur (n=37) (tethering index: 3.91 ± 1.01 vs 2.90 ± 1.17, p = 0.008; tethering angles of A3: 23.5° ± 8.9° vs 14.4° ± 11.4°, p = 0.012; P2: 44.4° ± 8.8° vs 28.2° ± 17.0°, p = 0.002; and P3: 35.2° ± 6.0° vs. 18.6° ± 12.7°, p < 0.001). Multivariate logistic regression analysis revealed the preoperative P3 tethering angle as an independent predictor of IMR recurrence with an optimal cutoff value of 29.9° (area under the curve, 0.92; 95% confidence interval, 0.84 to 1.00; p < 0.001). CONCLUSIONS: 3D echocardiography combined with valve modeling is predictive of recurrent IMR. Preoperative regional leaflet tethering of segment P3 is a strong independent predictor of IMR recurrence after undersized ring annuloplasty. In patients with a preoperative P3 tethering angle of 29.9° or larger, chordal-sparing valve replacement rather than valve repair should be strongly considered.

Protocol for prevention of spinal cord ischemia after thoracoabdominal aortic surgery.

OBJECTIVE: This manuscript was written to present a systemic protocol for the prevention, early detection, and treatment of spinal cord ischemia following open and endovascular thoracoabdominal aortic operations. METHODS: This protocol was a collaborative effort between surgeons, anesthesiologists and intensivists. It was implemented at our institution in November 2007. Nurses are trained to prevent, rapidly detect and ultimately aid in the treatment of spinal cord ischemia. RESULTS: Implementation of this protocol has aided in prevention, detection and treatment of spinal cord ischemia in patients after open and endovascular thoracoabdominal aortic operations. CONCLUSION: Standardized care and reliance on trained nursing staff to monitor for symptoms following thoracoabdominal aortic operations are safe and aid in the rapid detection, treatment and reversal of spinal cord ischemia.

Severity and Duration of Metabolic Acidosis After Deep Hypothermic Circulatory Arrest for Thoracic Aortic Surgery.

OBJECTIVE: To determine the severity, duration, and contributing factors for metabolic acidosis after deep hypothermic circulatory arrest (DHCA). DESIGN: Retrospective observational study. SETTING: University hospital. PATIENTS: Eighty-seven consecutive patients undergoing elective thoracic aortic surgery with DHCA. INTERVENTIONS: Regression analysis was used to test for relationships between the severity of metabolic acidosis and clinical and laboratory variables. MEASUREMENTS AND MAIN RESULTS: Minimum pH averaged 7.27±0.06, with 76 (87%) having a pH<7.35; 55 (63%), a pH<7.30; and 7 (8%), a pH<7.20. The mean duration of metabolic acidosis was 7.9±5.0 hours (range: 0.0 - 26.8), and time to minimum pH after DHCA was 4.3±2.0 hours (1.0 - 10.0 hours). Hyperchloremia contributed to metabolic acidosis in 89% of patients. The severity of metabolic acidosis correlated with maximum lactate (p<0.0001) and hospital length of stay (LOS) (r = 0.22, p<0.05), but not with DHCA time, DHCA temperature, duration of vasoactive infusions, or ICU LOS. Patient BMI was the sole preoperative predictor of the severity of postoperative metabolic acidosis. LIMITATIONS: This retrospective analysis involved short-term clinical outcomes related to pH severity and duration, which indirectly may have included the impact of sodium bicarbonate administration. CONCLUSIONS: Metabolic acidosis was common and severe after DHCA and was attributed to both lactic and hyperchloremic acidosis. DHCA duration and temperature had little impact on the severity of metabolic acidosis. The severity of metabolic acidosis was best predicted by the BMI and had minimal effects on short-term outcomes. Preventing hyperchloremic acidosis has the potential to decrease the severity of metabolic acidosis after DHCA.