Perioperative changes in coagulation and platelet contribution to clot strength after transcatheter aortic valve implantation: A study using thromboelastography and conventional markers.

INTRODUCTION: Thrombotic and haemorrhagic complications have been reported following transcatheter aortic valve implantation (TAVI). However, few reports have studied perioperative changes in coagulation and platelet function after TAVI. Furthermore, there are no clear guidelines for antithrombotic therapy. This study aimed to examine the perioperative changes in coagulation and platelet contribution to clot strength after TAVI using thromboelastography (TEG 6s; Hemonetics). METHODS: This prospective observational study included 15 patients scheduled to undergo TAVI for severe aortic stenosis. TEG 6s global haemostasis was used to record three measurements: on the day of surgery (immediately before the operation) and postoperative days 1 and 3. The reaction time R to thrombosis; K and α, which represent the rate of thrombosis; and the maximum amplitude (MA) were measured from the kaolin thromboelastography (TEG) curves. The coagulation index (CI) was calculated from the measurement results to assess thrombotic tendency. In addition, MA was converted to elastic clot strength, and platelet function was assessed by the difference, Gp, in elastic strength depending on platelet activation. RESULTS: R and K decreased, and α tended to increase in kaolin TEG on days 1 and 3 after TAVI, indicating elevated coagulation function compared with the preoperative period, but MA and CI did not show significant changes. Gp decreased significantly on days 1 and 3, suggesting a decrease in the platelet contribution to clot strength. CONCLUSIONS: Compared with the preoperative period, coagulation tended to increase, and platelet contribution to clot strength decreased from days 1 to 3 after TAVI.

New perforated radiation shield for anesthesiologists: Monte Carlo simulation of effects.

Catheterization for structural heart disease (SHD) requires fluoroscopic guidance, which exposes health care professionals to radiation exposure risk. Nevertheless, existing freestanding radiation shields for anesthesiologists are typically simple, uncomfortable rectangles. Therefore, we devised a new perforated radiation shield that allows anesthesiologists and echocardiographers to access a patient through its apertures during SHD catheterization. No report of the relevant literature has described the degree to which the anesthesiologist's radiation dose can be reduced by installing radiation shields. For estimating whole-body doses to anesthesiologists and air dose distributions in the operating room, we used a Monte Carlo system for a rapid dose-estimation system used with interventional radiology. The simulations were performed under four conditions: no radiation shield, large apertures, small apertures and without apertures. With small apertures, the doses to the lens, waist and neck surfaces were found to be comparable to those of a protective plate without an aperture, indicating that our new radiation shield copes with radiation protection and work efficiency. To simulate the air-absorbed dose distribution, results indicated that a fan-shaped area of the dose rate decrease was generated in the area behind the shield, as seen from the tube sphere. For the aperture, radiation was found to wrap around the backside of the shield, even at a height that did not match the aperture height. The data presented herein are expected to be of interest to all anesthesiologists who might be involved in SHD catheterization. The data are also expected to enhance their understanding of radiation exposure protection.

One-lung ventilation and 3D image analysis in a case of tracheal bronchus with steeply angled branching of left main bronchus: a case report.

BACKGROUND: Establishing one-lung ventilation (OLV) in patients with tracheal bronchus (TB) may be challenging due to its unusual bronchial anatomy. We present a case of difficult OLV in a patient with right TB and steeply angled bifurcation of the left main bronchus. CASE PRESENTATION: A 79-year-old woman was scheduled to undergo video-assisted thoracic surgery left upper lobectomy. We planned right OLV with a bronchial blocker; however, it was difficult to place the blocker in the left main bronchus due to a steep bifurcation angle. Therefore, we changed the entry angle of the lumen tip by advancing the tracheal tube to just above the tracheal bifurcation, allowing successful placement of the bronchial blocker into the bronchus. CONCLUSION: For airway management in patients with TB, especially for OLV, it is essential to understand the anatomy of the trachea, bronchus, and TB and to select the appropriate device for each case.

Changes in platelet function and coagulation after transcatheter aortic valve implantation evaluated with thromboelastography.

INTRODUCTION: The possibility of hypercoagulability during the perioperative period of transcatheter aortic valve implantation (TAVI) has been noted; however, there is still a controversy regarding the appropriate perioperative antithrombotic therapy. The study investigated coagulation and platelet functions during the TAVI perioperative period using thromboelastography (TEG) 6s platelet mapping. METHODS: A prospective observational study was conducted on 25 patients undergoing TAVI. TEG platelet mapping was performed at three time points: on admission to the operating room (before heparinisation), on postoperative day (POD) 1 and on POD 3. Perioperative changes observed included: maximum clot strength (MAHKH), clot strength without platelet function (MAActF), time to initiation of clots formation by coagulation factors (RHKH) and platelet function (Gp). Gp is activated by thrombin, and not affected by antiplatelet agents. It is calculated as [(5000×MAHKH)/(100 - MAHKH)] - [(5000×MAActF)/(100 - MAActF)]. Finally, MAADP/AA and GADP/AA, which reflect clot strength and platelet aggregation mediated by ADP/thromboxane A2 receptors, respectively, were also examined using the same method as for Gp. RESULTS: MAHKH continued to decrease until POD 3, indicating antithrombotic change after TAVI. Gp continuously decreased for 3 days after TAVI, while MAActF increased significantly on POD 3. Furthermore, RHKH shortened on POD 1 and POD 3, suggesting increased coagulation capacity after TAVI. Finally, GADP in clopidogrel-naive patients was reduced for 3 days after TAVI, while GAA in aspirin-naive patients showed no significant change perioperatively. CONCLUSIONS: In this study involving TEG platelet mapping, coagulation capacity increased while platelet function decreased, resulting in antithrombotic change for 3 days after TAVI. The ADP receptor system may be implicated in the decreased platelet function. These results may be useful for considering optimal perioperative antithrombotic therapy in TAVI.

Temporary worsening of mitral regurgitation due to conduction disturbance after transcatheter aortic valve implantation.

BACKGROUND: Mitral regurgitation after transcatheter aortic valve implantation (TAVI) can be caused by various etiologies. CASE PRESENTATION: An 81-year-old woman with mild mitral regurgitation and complete right bundle branch block was scheduled to undergo TAVI under general anesthesia. After the deployment of the prosthetic valve, electrocardiography depicted a wide QRS wave and bradycardia, suggestive of complete atrioventricular block. Although there was no lesion indicative of tissue injury to the valve itself, worsening of mitral regurgitation was identified on transesophageal echocardiography. The hemodynamic condition was stable, and no additional procedure was performed. Electrocardiography depicted a return to a narrow QRS wave 3 days after surgery, and the mitral regurgitation appeared comparable to the preoperative grade. We assumed that the worsening of mitral regurgitation was caused by dyssynchrony in the left ventricle due to the conduction disorder. CONCLUSIONS: Mitral regurgitation after TAVI needs observation, including the determination of the etiology and treatment principle.

High-intensity transient signals during transcatheter aortic valve implantation assessed by ultrasonic carotid artery blood-flow monitoring: A single center prospective observational study.

BACKGROUND: No reports to date have assessed the procedural patterns of high-intensity transient signals (HITS) by monitoring blood flow in cervical arteries. The aim of this study was to examine the sequential distribution of HITS in each procedural phase and predictive factors for HITS during transcatheter aortic valve implantation (TAVI) by monitoring blood flow in the common carotid artery. METHODS: This prospective observational study included 73 patients who underwent TAVI via the transfemoral artery approach. We continuously evaluated and analyzed HITS from administration of heparin to valve implantation. RESULTS: HITS peaked during balloon valvuloplasty (BAV), amounting to almost 30% of the total HITS count, followed by valve implantation [BAV 141 (73-186) and valve implantation 86 (64-126), respectively]. In univariate and multivariate analysis, the Agatston score of the aortic valve and low-density lipoprotein were confirmed as independent predictors of HITS frequency with logarithmically converted coefficients of 0.00015 (p < 0.001) and 0.0032 (p = 0.027), respectively. CONCLUSIONS: These results provide the first evidence that micro-emboli deriving from calcified burden were scattered primally during BAV, followed by valve implantation. The Agatston score may be a predictor for the amount of HITS.