Perioperative Factors Associated With Intraoperative Transfusion in Patients Undergoing Major Lower Limb Amputation.

BACKGROUND: Intraoperative transfusions in vascular patients undergoing major lower limb amputations (LLAs) are associated with worse postoperative outcomes. METHODS: We conducted a retrospective study from 2015 to 2020 to identify perioperative factors associated with the need for intraoperative transfusion for patients undergoing below knee or above knee amputations secondary to vascular disease. RESULTS: A total of 65 patients with major LLAs were identified, 39 (60%) with below knee and 26 (40%) with above knee amputations. There were 15 (23%) patients who were transfused intraoperatively and 50 (77%) who were not. Six (15%) of the below knee patients and 9 (34%) of the above knee patients required intraoperative transfusion. Of the variables studied, only preoperative hemoglobin (8.6 ± .4 vs 9.9 ± .2 g/dL, P = .01), change in hemoglobin (-.1 ± .4 vs .8 ± .2 g/dL, P = .01), estimated intraoperative blood loss (416 ± 168 vs 126 ± 14 mL, P = .04), and operative duration (116 ± 19 min. vs 89 ± 6 min, P = .046) were associated with a transfusion requirement with these patients having a longer length of stay (42 [13-76] vs 21 [12-31] days, P = .04) and a higher risk of mortality (33% vs 10%, P = .03). DISCUSSION: The study is limited by a small sample size from a single institution. However, patients who received an intraoperative transfusion had a lower starting hemoglobin, higher estimated blood loss, required longer hospital stays, and were at a higher risk for post-discharge mortality.

Physician-modified fenestrated endograft for postdissection thoracoabdominal aortic aneurysm following provisional extension to induce complete attachment and renal artery stenting.

We have described a patient with a history of type A-11 dissection repair, who subsequently underwent thoracic endovascular aortic repair with distal bare metal dissection stents (provisional extension to induce complete attachment) and renal artery stenting for malperfusion. During the next 3 years, the thoracoabdominal aorta had continued to enlarge to 6.9 cm, despite false lumen embolization and thoracic endovascular aortic repair extension. Given the continued aortic enlargement, physician-modified fenestrated endovascular aortic repair was performed within the prior aortic and renal stents with successful aneurysm sealing. The results from the present case have illustrated that continued aneurysmal degeneration can occur after provisional extension to induce complete attachment and that subsequent physician-modified fenestrated endovascular aortic repair is feasible.

Contact-force recovery predicts the absence of cardiac perforation during steam pops.

PURPOSE: Cardiac perforation (CP) is an uncommon but clinically important complication of radiofrequency ablation (RFA). We previously showed that contact-force recovery after a steam pop predicts the absence of CP in an open-chest animal model after pericardial dissection. We attempted to determine whether this also applies when pericardium is present. METHODS: In 5 open-chest sheep, left atrial RFA was performed under direct observation with a 7.5F ThermoCool SmartTouch force-sensing catheter (Biosense Webster Inc., Irvine, CA, USA). The catheter's contact force was measured every 50 ms during RFA. After each steam pop, the presence (+) or absence (-) of CP was noted, as well as whether pericardium was present over the ablation site. Contact-force signals were analyzed to detect contact-force recovery. Perforation rates were compared between sites with or without pericardium. RESULTS: Ninety-six steam pops occurred: 77 with pericardium and 19 without. For the pericardial steam pops, contact-force recovery occurred in 31/60 CP- events (52%) and 1/17 CP+ events (6%; P = 0.0006). For nonpericardial steam pops, contact-force recovery occurred in 4/9 CP- events (44%) and 1/10 CP+ events (P = 0.14). The rate of CP was 22% with pericardium and 52% without (P = 0.02). Pericardial tissue charred extensively during steam pop induction, even in the absence of CP. CONCLUSIONS: Contact-force recovery predicts the absence of CP during RFA independently of whether the pericardium is present. The presence of the pericardium may decrease the likelihood of perforation, perhaps by acting as a thermal sink. Additional studies are needed to correlate these results with clinical experience.

Low Incidence of Pump-Related Infections in Jarvik 2000 Ventricular Assist Device Recipients with a Subcostal Driveline Exit Site.

Driveline infection has been a persistent problem with mechanical cardiac assist devices. The reported incidence of infection has been low in patients who receive a Jarvik 2000 continuous-flow left ventricular assist device when a skull-pedestal driveline exit site is used. We evaluated whether this is also true when a subcostal driveline exit site is used. We reviewed baseline demographic variables, postimplantation vital signs, laboratory values, and culture results in patients who underwent Jarvik 2000 implantation at our center from April 2000 through October 2009, including follow-up through June 2014. All patients had a subcostal driveline exit site. We defined device-related infection as a positive blood or wound culture associated with a medical or surgical device intervention. Event and time-to-event rates were calculated. Eighty-one patients received 89 Jarvik 2000 devices, all as bridges to transplantation. The median support duration was 69 days (interquartile range, 27-153 d; range, 2-2,249 d). Five superficial driveline infections and one incision-site infection occurred (0.002 events per patient-year of support). The median time from pump implantation to onset of driveline infection was 30 days; the incision-related infection occurred at 44 days. The Jarvik 2000 has a low incidence of infection when implanted with use of a subcostal driveline exit site. The incidence of pump infections is particularly low. Using a subcostal driveline exit site may be as effective in preventing infections as using a skull-pedestal driveline exit site. We detail our findings in this report.

Near-field impedance accurately distinguishes among pericardial, intracavitary, and anterior mediastinal position.

INTRODUCTION: Epicardial catheter ablation is increasingly used to treat arrhythmias with an epicardial component. Nevertheless, percutaneous epicardial access remains associated with a significant risk of major complications. Developing a technology capable of confirming proper placement within the pericardial space could decrease complication rates. The purpose of this study was to examine differences in bioimpedance among the pericardial space, anterior mediastinum, and right ventricle. METHODS: An ovine model (n = 3) was used in this proof-of-concept study. A decapolar catheter was used to collect bipolar impedance readings; data were collected between each of five electrode pairs of varying distances. Data were collected from three test regions: the pericardial space, anterior mediastinum, and right ventricle. A control region in the inferior vena cava was used to normalize the data from the test regions. Analysis of variance was used to test for differences among regions. RESULTS: A total of 10 impedance values were collected in each animal between each of the five electrode pairs in the three test regions (n = 340) and the control region (n = 145). The average normalized impedance values were significantly different among the pericardial space (1.760 ± 0.370), anterior mediastinum (3.209 ± 0.227), and right ventricle (1.024 ± 0.207; P < 0.0001). In post hoc testing, the differences between each pair of regions were significant, as well (P < 0.001 for all). CONCLUSION: Impedance values are significantly different among these three anatomical compartments. Therefore, impedance can be potentially used as a means to guide percutaneous epicardial access.

Effect of botulinum toxin on inducibility and maintenance of atrial fibrillation in ovine myocardial tissue.

BACKGROUND: Aberrant vagal stimulation may promote the generation and propagation of atrial fibrillation (AF). Researchers have suggested that botulinum toxin (BTX), a neurotoxin that decreases neural vagal stimulation, may decrease the incidence of postoperative AF. The exact electrophysiologic mechanism underlying the observations and histopathologic alterations associated with BTX are unclear. OBJECTIVE: To investigate the electrophysiologic, functional, and histopathologic effects of BTX on fibrillation induction in ovine atria. METHODS: Eight sheep underwent BTX injections into their pulmonary veins, atrial fat pads, and ventricular walls. Electrophysiology with pacing was performed at baseline and 7 days after injection to evaluate the atrial effective refractory period (ERP) and vulnerability to AF with and without vagal stimulation. Echocardiography was performed at baseline and day 7. After euthanasia, histopathologic analysis was performed. RESULTS: Seven sheep completed the study. For both atria, there was significant shortening in the ERP with vagal stimulation versus no stimulation on day 0 but not on day 7. More aggressive pacing was required to induce AF in the left atrium on day 7 than on day 0. Echocardiography on day 7 showed no significant changes in ejection fraction or new wall-motion abnormalities of the left and right ventricle. Histopathologic analysis showed no significant adverse effects. CONCLUSION: The subacute BTX effect reduced the vulnerability of atrial tissue to AF induction and reduced the vagal influence on atrial ERP shortening compared to baseline levels. Direct BTX injection did not cause myocardial dysfunction or histologic adverse effects.

Accuracy of Voltage Signal Measurement During Radiofrequency Delivery Through the SMARTTOUCH Catheter.

INTRODUCTION: Current methods for measuring voltage during radiofrequency (RF) ablation (RFA) necessitate turning off the ablation catheter. If voltage could be accurately read without signal attenuation during RFA, turning off the catheter would be unnecessary, allowing continuous ablation. We evaluated the accuracy of the Thermocool SMARTTOUCH catheter for measuring voltage while RF traverses the catheter. METHODS AND RESULTS: We studied 26 patients undergoing RFA for arrhythmias. A 7.5F SMARTTOUCH catheter was used for sensing voltage and performing RFA. Data were collected from the Carto-3 3-dimensional mapping system. Voltages were measured during ablation (RF-ON) and immediately before or after ablation (RF-OFF). In evaluating the accuracy of RF-ON measurements, we utilized the RF-OFF measure as the gold standard. We measured 465 voltage signals. The median values were 0.2900 and 0.3100 for RF-ON and RF-OFF, respectively. Wilcoxon signed rank testing showed no significant difference in these values (P = 0.608). The intraclass correlation coefficient (ICC) was 0.96, indicating that voltage measurements were similarly accurate during RF-OFF versus RF-ON. Five patients had baseline atrial fibrillation (AF), for whom 82 ablation points were measured; 383 additional ablation points were measured for the remaining patients. The voltages measured during RF-ON versus RF-OFF were similar in the presence of AF (P = 0.800) versus non-AF rhythm (P = 0.456) (ICC, 0.96 for both). CONCLUSION: Voltage signal measurement was similarly accurate during RF-ON versus RF-OFF independent of baseline rhythm. Physicians should consider not turning off the SMARTTOUCH ablation catheter when measuring voltage during RFA.

Electromyography as a new means of navigation during endotracheal intubation.

This study tested a method of using rapid analysis of electromyographic response patterns to electrical stimulation to enable real-time navigation during endotracheal intubation. An electromyographic response detection device was constructed and integrated into a standard endotracheal tube. The rebound rates of the response voltages were measured in the trachea and oesophagus after stimulation in an acute study performed in three freshly euthanized male Suffolk sheep. In a blind study, a physician attempted to identify the tissue type solely from the electrical response signals. In the acute study, the observed rebound rate was found to be significantly faster in tracheal tissue (2.21 × 10(-3) V s(-1)) than in oesophageal tissue (3.45 × 10(-2) V s(-1); p = 0.000 05). In the blind study, the physician correctly determined the oesophagus response rate seven out of eight times and the tracheal rate eight out of nine times. These results suggest that electromyographic responses can be used to accurately differentiate tracheal from oesophageal tissue during ETT insertion, thus offering a valuable new means of enhancing patient safety.