Investigation of raphe function in the bicuspid aortic valve and its influence on clinical criteria-A patient-specific finite element study

The aortic valve is normally composed of 3 cusps. In one common lesion, 2 cusps are fused together. The conjoined area of the fused cusps is termed raphe. Occurring in 1% to 2% of the population, the bicuspid aortic valve (BAV) is the most common congenital cardiac malformation. The majority of BAV patients eventually require surgery. There is a lack in the literature regarding modeling of the raphe (geometry and material properties), its role and its influence on BAV function. The present study aims to propose improvements on these aspects. Three patient-specific finite element models of BAVs were created based on 3D trans-esophageal echocardiography measurements, and assuming age-dependent material properties. The raphe was initially given the same material properties as its underlying cusps. Two levels of validation were performed; one based on the anatomical validation of the pressurized geometry in diastole (involving 7 anatomical measures), as simulated starting from the unpressurized geometry, and the other based on a functional assessment using clinical measurements in both systole and diastole (involving 16 functional measures). The pathology was successfully reproduced in the FE models of all 3 patients. To further investigate the role of the raphe, 2 additional scenarios were considered; (1) the raphe was considered as almost rigid, (2) the raphe was totally removed. The results confirmed the interpretation of the raphe as added stiffness in the fused cusp's rotation with respect to the aortic wall, as well as added support for stress distribution from the fused cusps to the aortic wall.

Healthcare providers' perceptions of a situational awareness display for emergency department resuscitation: a simulation qualitative study

Importance

Emergency resuscitation of critically ill patients can challenge team communication and situational awareness. Tools facilitating team performance may enhance patient safety.

Objectives

To determine resuscitation team members' perceptions of the Situational Awareness Display's utility.

Design

We conducted focus groups with healthcare providers during Situational Awareness Display development. After simulations assessing the display, we conducted debriefs with participants.

Setting

Dual site tertiary care level 1 trauma centre in Ottawa, Canada.

Participants

We recruited by email physicians, nurses and respiratory therapist.

Intervention

Situational Awareness Display, a visual cognitive aid that provides key clinical information to enhance resuscitation team communication and situational awareness.

Main outcomes and measures

Themes emerging from focus groups and simulation debriefs. Three reviewers independently coded and analysed transcripts using content qualitative analysis.

Results

We recruited a total of 33 participants in two focus groups (n = 20) and six simulation debriefs with three 4-5 member teams (n = 13). Majority of participants (10/13) strongly endorsed the Situational Awareness Display's utility in simulation (very or extremely useful). Focus groups and debrief themes included improved perception of patient data, comprehension of context and ability to project to future decisions. Participants described potentially positive and negative impacts on patient safety and positive impacts on provider performance and team communication. Participants expressed a need for easy data entry incorporated into clinical workflow and training on how to use the display.

Conclusion

Emergency resuscitation team participants felt the Situational Awareness Display has potential to improve provider performance, team communication and situational awareness, ultimately enhancing quality of care.

Team communication patterns in emergency resuscitation: a mixed methods qualitative analysis

BACKGROUND

In order to enhance patient safety during resuscitation of critically ill patients, we need to optimize team communication and enhance team situational awareness but little is known about resuscitation team communication patterns. The objective of this study is to understand how teams communicate during resuscitation; specifically to assess for a shared mental model (organized understanding of a team's relationships) and information needs.

METHODS

We triangulated 3 methods to evaluate resuscitation team communication at a tertiary care academic trauma center: (1) interviews; (2) simulated resuscitation observations; (3) live resuscitation observations. We interviewed 18 resuscitation team members about shared mental models, roles and goals of team members and procedural expectations. We observed 30 simulated resuscitation video recordings and documented the timing, source and destination of communication and the information category. We observed 12 live resuscitations in the emergency department and recorded baseline characteristics of the type of resuscitations, nature of teams present and type and content of information exchanges. The data were analyzed using a qualitative communication analysis method.

RESULTS

We found that resuscitation team members described a shared mental model. Respondents understood the roles and goals of each team member in order to provide rapid, efficient and life-saving care with an overall need for situational awareness. The information flow described in the interviews was reflected during the simulated and live resuscitations with the most responsible physician and charting nurse being central to team communication. We consolidated communicated information into six categories: (1) time; (2) patient status; (3) patient history; (4) interventions; (5) assistance and consultations; 6) team members present.

CONCLUSIONS

Resuscitation team members expressed a shared mental model and prioritized situational awareness. Our findings support a need for cognitive aids to enhance team communication during resuscitations.

Can teamwork and situational awareness (SA) in ED resuscitations be improved with a technological cognitive aid? Design and a pilot study of a team situation display

Effective teamwork in ED resuscitations, including information sharing and situational awareness, could be degraded. Technological cognitive aids can facilitate effective teamwork.

OBJECTIVE

This study focused on the design of an ED situation display and pilot test its influence on teamwork and situational awareness during simulated resuscitation scenarios.

MATERIAL AND METHODS

The display design consisted of a central area showing the critical dynamic parameters of the interventions with an events time-line below it. Static information was placed at the sides of the display. We pilot tested whether the situation display could lead to higher scores on the Clinical Teamwork Scale (CTS), improved scores on a context-specific Situational Awareness Global Assessment Technique (SAGAT) tool, and team communication patterns that reflect teamwork and situational awareness.

RESULTS

Resuscitation teamwork, as measured by the CTS, was overall better with the presence of the situation display as compared with no situation display. Team members discussed interventions more with the situation display compared with not having the situation display. Situational awareness was better with the situation display only in the trauma scenario.

DISCUSSION

The situation display could be more effective for certain ED team members and in certain cases.

CONCLUSIONS

Overall, this pilot study implies that a situation display could facilitate better teamwork and team communication in the resuscitation event.

Aortic Valve Cusp Coaptation Surface Area Using 3-Dimensional Transesophageal Echocardiography Correlates with Severity of Aortic Valve Insufficiency

OBJECTIVE

The aim of this study was to test both in humans and using finite element (FE) aortic valve (AV) models whether the coaptation surface area (CoapSA) correlates with aortic insufficiency (AI) severity due to dilated aortic roots to determine the validity and utility of 3-dimensional transesophageal echocardiographic-measured CoapSA.

DESIGN

Two-pronged, clinical and computational approach.

SETTING

Single university hospital.

PARTICIPANTS

The study comprised 10 patients with known AI and 98 FE simulations of increasingly dilated human aortic roots.

INTERVENTIONS

The CoapSA was calculated using intraoperative 3-dimensional transesophageal echocardiography data of patients with isolated AI and compared with established quantifiers of AI. In addition, the CoapSA and effective regurgitant orifice area (EROA) were determined using FE simulations.

MEASUREMENTS AND MAIN RESULTS

In the 10 AI patients, regurgitant fraction (RF) increased with EROA (R² = 0.77, p = 0.0008); CoapSA decreased with RF (R² = 0.72, p = 0.0020); CoapSA decreased with EROA (R² = 0.71, p = 0.0021); and normalized CoapSA (CoapSA / [Ventriculo-Aortic Junction × Sinotubular Junction]) decreased with EROA (R² = 0.60, p = 0.0088). In the 98 FE simulations, normalized CoapSA decreased with EROA (R² = 0.50, p = 0.0001).

CONCLUSIONS

In both human and FE AV models, CoapSA was observed to be inversely correlated with AI severity, EROA, and RF, thereby supporting the validity and utility of 3D TEE-measured CoapSA. A clinical implication is the expectation that high values of CoapSA, measured intraoperatively after AV repairs, would correlate with better long-term outcomes of those repairs.

Impact of aortic annular geometry on aortic valve insufficiency: Insights from a preclinical, ex vivo, porcine model

OBJECTIVES

We sought to create a model of aortic insufficiency in a left heart simulator combined with 3-dimensional echocardiography and finite element modeling of the aortic valve. We examined the effects of aortic root geometry alteration on aortic insufficiency.

METHODS

Porcine aortic roots were analyzed on a left heart simulator before (control, n = 8) and after intervention (n = 8). Intervention entailed 3 vertical incisions at the sinotubular junction with diamond-shaped patches incorporated into the defects to increase the sinotubular junction diameter. Hemodynamic parameters were assessed, including regurgitant volume and fraction. Video and echocardiography images evaluated aortic valve function, coaptation surface area, aortic insufficiency, and effective regurgitant orifice area. Finite element modeling corroborated relationships between root geometry and aortic insufficiency, and examined cusp stress.

RESULTS

The intervention resulted in a sinotubular junction diameter increase of 55% ± 4%. The sinotubular junction to ventriculo-aortic junction diameter ratio was significantly higher in the intervention group (1.89 ± 0.16 vs 1.47 ± 0.04, P = .02). Increased sinotubular junction diameter resulted in aortic insufficiency assessed by regurgitant volume (28 ± 7 mL vs 5 ± 2 mL, P = .004), regurgitant fraction (36% ± 5% vs 7% ± 1%, P < .001), and effective regurgitant orifice (15 ± 5 mm(2) vs 0 mm(2), P = .016). Intervention coaptation surface area was smaller (1.03 ± 0.11 cm(2) vs 1.80 ± 0.08 cm(2), P < .001). There was a linear correlation between increased sinotubular junction/ventriculo-aortic junction ratio and regurgitant fraction (R(2) = 0.65, P = .003). The finite element modeling demonstrated a similar relationship between increasing sinotubular junction diameter and aortic insufficiency severity, and between end-diastolic cusp stresses and sinotubular junction diameters (R(2) = 0.98, P < .001).

CONCLUSIONS

In this model, increasing sinotubular junction diameter is linearly related to reduced coaptation surface area and increasing aortic insufficiency severity. This model provides new insights into aortic insufficiency mechanisms and may be used to evaluate novel interventions for aortic valve repair.

Transesophageal echocardiography simulation is an effective tool in teaching psychomotor skills to novice echocardiographers

BACKGROUND

Performance of transesophageal echocardiography (TEE) requires the psychomotor ability to obtain interpretable echocardiographic images. The purpose of this study was to determine the effectiveness of a simulation-based curriculum in which a TEE simulator is used to teach the psychomotor skills to novice echocardiographers and to compare instructor-guided with self-directed online delivery of the curriculum.

METHODS

After institutional review board approval, subjects inexperienced in TEE completed an online review of TEE material prior to a baseline pre-test of TEE psychomotor skills using the simulator. Subjects were randomized to two groups. The first group received an instructor-guided lesson of TEE psychomotor skills with the simulator. The second group received a self-directed slide presentation of TEE psychomotor skills with the simulator. Both lessons delivered identical information. Following their respective training sessions, all subjects performed a post-test of their TEE psychomotor skills using the simulator. Two assessors rated the TEE performances using a validated scoring system for acquisition of images.

RESULTS

Pre-test TEE simulator scores were similar between the two instruction groups (9.0 vs 5.0; P = 0.28). The scores in both groups improved significantly following training, regardless of the method of instruction (P < 0.0001). The improvement in scores (post-test scores minus pre-test scores) did not differ significantly between instruction groups (12.5 vs 14.5; P = 0.55). There was strong inter-rater reliability between assessors (α = 0.98; 95% confidence interval [CI]: 0.97 to 0.99).

CONCLUSIONS

High-fidelity TEE simulators are an effective training adjunct for the acquisition of basic TEE psychomotor skills. There was no difference in improvement between the different modalities of instruction. Further research will examine the need for a faculty resource for a curriculum in which a simulator is used as an adjunct.

Handsewn proximal anastomoses onto the ascending aorta through a small left thoracotomy during minimally invasive multivessel coronary artery bypass grafting: a stepwise approach to safety and reproducibility

Minimally invasive coronary artery bypass grafting (MICS CABG) is a nonrobotic, nonthoracoscopic operation that achieves complete anatomical graft similarity with conventional CABG, while avoiding sternotomy and cardiac anoxia. We describe the stepwise approach to perform proximal anastomoses directly off the ascending aorta and also early results of this operation. All myocardial territories are accessed via a 4- to 6-cm left fifth intercostal thoracotomy. After takedown of the left internal thoracic artery, the ascending aorta is progressively brought into view by the following maneuvers: (1) administration of cardiac inotropes to minimize right ventricle filling, (2) increase in right lung positive end-expiratory pressures and tidal volumes, (3) placement of multilevel pericardial retractions, (4) leftward displacement of the ascending aorta with a gauze anterior to the superior vena cava, and (5) left posteroinferior displacement of the right ventricular outflow tract with an epicardial stabilizer. Handsewn proximal anastomoses can then be performed on the ascending aorta with a side-biting clamp. In the first 100 patients who underwent multivessel MICS CABG with proximal anastomoses directly off the aorta, the mean age was 62.6 ± 10.2 years, and median operative time was 3.5 hours. The mean number of grafts was 2.3 ± 0.5, and there were 3 conversions to open sternotomy. There were no preoperative deaths, 2 reoperations for bleeding, and 2 superficial wound infections. The median length of hospital stay was 4 days. MICS CABG is a safe alternative to conventional CABG, with excellent short-term results.

Communication and team situation awareness in the OR: Implications for augmentative information display

Team Situation Awareness (TSA) is one of the critical factors in effective Operating Room (OR) teamwork and can impact patient safety and quality of care. While previous research showed a relationship between situation awareness, as measured by communication events, and team performance, the implications for developing technology to augment and facilitate TSA were not examined. This research aims to further study situation-related communications in the cardiac OR in order to uncover potential degradation in TSA which may lead to adverse events. The communication loop construct-the full cycle of information flow between the participants in the sequence-was used to assess susceptibility to breakdown. Previous research and the findings here suggest that communication loops that are open, non-directed, or with delayed closure, can be susceptible to information loss. These were quantitatively related to communication indicators of TSA such as questions, replies, and announcements. Taken together, both qualitative and quantitative analyses suggest that a high proportion of TSA-related communication (63%) can be characterized as susceptible to information loss. The findings were then used to derive requirements and design a TSA augmentative display. The design principles and potential benefits of such a display are outlined and discussed.

EMLA Cream is an Effective Topical Anesthetic for Bronchoscopy

BACKGROUND:EMLA cream (AstraZeneca Inc, Canada) (1:1 eutectic mixture of lidocaine 2.5% and prilocaine 2.5%) has traditionally been used for topical anesthesia of the skin. Recent reports of EMLA's use for anesthesia of the oral mucosa suggest an application in topical anesthesia for bronchoscopy.

OBJECTIVES:To evaluate the amount of local anesthetic administered during bronchoscopy; to assess the time required to obtain topical anesthesia; to assess the quality of the topical anesthesia as described by bronchoscopists; and to document any complications.

METHODS:Fifty-seven unpremedicated patients had 4 mL of EMLA cream applied to the posterior third of their tongues on arrival in the bronchoscopy suite. Liquid lidocaine was applied through the bronchoscope for laryngeal anesthesia.

RESULTS:The mean time from the application of EMLA cream to insertion of the bronchoscope was 5.10±0.48 min. Fifty-six patients (98.2%) required no supplemental anesthesia. Bronchoscopy conditions were described as 'excellent' in 55 cases (96.5%) and 'good' in the remaining two cases (3.5%).

CONCLUSIONS:EMLA is an effective alternative for oropharyngeal topical anesthesia that is well-tolerated by patients.

Comparison of postoperative pain: tonsillectomy by blunt dissection or electrocautery dissection

PURPOSE

To compare post-operative pain in children undergoing tonsillectomy by blunt dissection or electrocautery.

METHOD

Thirty-six children between the ages of 5 and 15 years were recruited for the study. Tonsillectomy was done in a standardized fashion with uniform anaesthetic practices. Each child kept a pain diary for 10 days, recording pain twice daily on a Visual Analog Scale and Faces Pain Scale. Doses of analgesics were recorded.

RESULTS

There were no statistically significant differences in the pain scores for the groups, although there was a trend toward more pain in the blunt dissection group. There were more complications in this group, and these children used significantly more doses of acetaminophen. Sources of bias are discussed.

CONCLUSION

These results suggest a trend toward greater postoperative pain in children who have tonsillectomies by blunt dissection techniques.