Patient-specific Hemodynamics of Severe Carotid Artery Stenosis Before and After Endarterectomy Examined by 4D Flow MRI.

Carotid endarterectomy (CEA) influences the carotid endoluminal anatomy, which results in hemodynamic changes before and after surgery. We investigated the hemodynamics of severe carotid artery stenosis before and after conventional endarterectomy with/without patch repair. An in vitro experiment utilizing carotid phantoms, which underwent a procedure that emulated CEA with/without the patch repair, was performed with a high-spatiotemporal resolution using 4D flow MRI. We evaluated an abnormal region of carotids, which consists of the normalized time-averaged wall shear stress (NTA|WSS|) and the oscillatory shear index (OSI), to account for continuous high-shear regions (high NTA|WSS| and low OSI) and chaotic low-shear regions, i.e., stenosis-prone regions (low NTA|WSS| and high OSI). The use of normalized hemodynamic parameters (e.g., NTA|WSS|) allowed comparison of diverse cases with different conditions of hemodynamics and vessel geometry. We observed that the stenosis-prone regions of the carotids with patches were noticeably larger than the corresponding regions in no-patch carotids. A large recirculating flow zone found in the stenosis-prone region of the internal carotid artery (ICA) of the postoperative carotids with patches partially blocks the flow path into ICA, and consequently the flow rate was not recovered after surgery unlike an expectation.

Reduced amputation rate with isovolemic hemodilution in critical limb ischemia patients.

AIMS: Critical limb ischemia (CLI) patients are characterized by intractable pain in spite of medication, non-healing ulcers, and gangrene. The objective of this study was to investigate whether or not isovolemic hemodilution treatment can reduce the rate of major amputations in CLI. METHODS: 28 patients were studied who had tissue loss on Rutherford Grade III, Category 5 or 6. The subjects were divided into two arms: standard-of-care, conventional therapy (CT) (n = 15) as a control group and hemodilution therapy (HT) (n = 13) as a study group. For the HT group, weekly isovolemic hemodilution was performed over 4 consecutive weeks, removing 250 ml of whole blood with the infusion of hydroxyl-ethyl starch solution. Blood viscosity, hematocrit, hemoglobin, ankle-brachial index, VA pain scale, time-to-amputation from admission, and survival time were measured. RESULTS: The mean Hct gradually decreased from 36.6 to 35.1, whereas the WBV at a shear rate of 1 s-1 significantly decreased from 18.2 to 10.5 during the same period. Subsequently, tissue oxygen delivery index, defined as the ratio of Hct to WBV at a shear rate of 1 s-1, increased from 24.4 to 37.0 by 51.7%, suggesting improvements in oxygen delivery in the patients. The average rate of lower limb major amputation in the control group was 93% (14/15), whereas that in the study group was 31% (4/13) (p = 0.001). Amputation-free median survival time and amputation-free 5-year survival rate in the control group were 1.2 months and 7%, while those in the study group were 30.2 months and 44% (p = 0.001). There were no adverse effects from repetitive hemodilution in the study group. CONCLUSIONS: Isovolemic hemodilution treatment of CLI patients was found to be well-tolerated and reduced the rate of major amputation resulting from the deterioration of CLI.

Awake extracorporeal membrane oxygenation bridging for pulmonary retransplantation provides comparable results to elective retransplantation.

BACKGROUND: Lung retransplantation became an accepted treatment for bronchiolitis obliterans syndrome (BOS). However, the value of different bridging modalities for these patients is controversial. METHODS: We analyzed outcomes of 39 patients listed for retransplantation between 2008 and 2012. Patients were divided in 3 groups: 23 patients without any bridge modality (elective, Group 1), 11 patients on ventilation and full sedation with or without extracorporeal membrane oxygenation (ECMO) support (sedated bridging, Group 2), and 5 patients awake on ECMO support (awake bridging, Group 3). RESULTS: Waiting list mortality was 13% in Group 1, 39% in Group 2, and 0% in Group 3. Perioperative mortality was 20% in Group 1, 29% in Group 2, and 0% in Group 3. Significant differences between Groups 1 and 2 were calculated for time on post-operative ventilation (17.4 vs 27.3 days, p = 0.022), intensive care unit stay (22.0 vs 32.9 days, p = 0.026), and hospital stay (34.7 vs 54.1 days, p = 0.013). However, there were no significant differences between Groups 1 and 3 for post-operative ventilation time (17.4 vs 13.4 days, p = 0.192), for intensive care unit stay (22.0 vs 26.4 days, p = 0.169), or for hospital stay (34.7 vs 34.8 days, p = 0.367). Survival rates at 90 days, 1 year, and 2 years were 80%, 70%, and 53% in Group 1; 71%, 43%, and 29% in Group 2; and 100%, 60%, and 60% in Group 3, respectively. CONCLUSION: Awake ECMO bridging for retransplantation provides comparable results to elective retransplantation.

Influence of non-Newtonian viscosity of blood on microvascular impairment.

The present research investigated the role of blood viscosity on flow within a microvascular network to identify the conditions of blood flow stagnation. When the yield stress of blood was less than 0.005 Pa, there were no stagnant regions in the microvasculature. However, when the yield stress increased to 0.05 Pa, stagnant or reduced flow areas began to appear, which grew and expanded rapidly with further increase in the yield stress. Thus, the yield stress determined from blood viscosity profile of a patient can be utilized to evaluate the risk of circulatory impairment.

Detection of atrial arrhythmia in superconducting quantum interference device magnetocardiography; preliminary result of a totally-noninvasive localization method for atrial current mapping.

Map-guided surgery is the goal for treatment of atrial fibrillation (AF), because it minimizes unnecessary incisions or procedures. We propose a totally-noninvasive and even non-contact method to detect atrial arrhythmia with a superconducting quantum interference device magnetocardiography (MCG) system, and report the first clinical application case of MCG map-guided AF surgery. To detect weak atrial excitation, we utilized a high sensitive 64-channel MCG system measuring tangential magnetic field components, which is known to be more sensitive to a deeper current source. We measured the MCG signals from eight patients with chronic AF. Then, we separated the f-wave from the other components by using independent component analysis. The extracted f-wave caused by reentrant myocardial excitation was three-dimensionally localized on the mesh model of a human heart by a novel beamformer technique having a surface action potential activity as its filter output. We localized the abnormal stimulation source of an atrial arrhythmia non-invasively and visualized the current source distribution corresponding to the atrial excitation successfully on the three-dimensional atrial surface, which was separated from the ventricular excitation. Using this atrial mapping, we underwent minimal AF surgery in three patients and converted their AF to sinus rhythm successfully.

Touch print cytology shows higher sensitivity than pleural lavage cytology for pleural micro-metastasis in lung cancer.

Many authors have used pleural lavage cytology for confirming pleural micro-metastasis in lung cancer, but the results showed relatively low sensitivity having positive range of 4-14%. So, if we have a method with higher sensitivity than lavage cytology, the significance of pleural micro-metastasis will be elucidated clearly. To detect micro-metastasis, we underwent touch print cytology using glass slides and lavage cytology. Just after thoracotomy, touch print was carried with 2 pieces of glass slide from the visceral pleural surface of tumor mass. Then, two lavage cytology were collected at the times of pre-resection and post-resection (after distilled water irrigation) using each 1 liter of saline. The glass slides and lavages were examined for confirming micro-metastasis of cancer cells. From June 1998 to May 2004, 146 tumor masses of lung cancer have been subjected. Among them, 127 sets of cytology slides were reviewed completely in the last one month. Touch print cytology was found to be positive in 81.9% (104/127), while lavage cytology in 4.7% (6/127) of pre-resection and in 0.8% (1/127) of post-resection. To detect pleural micro-metastasis, touch print cytology using a glass slide can be considered as an easy and effective method having higher sensitivity than lavage cytology.

Feasibility of latissimus dorsi and serratus anterior muscle-sparing vertical thoracotomy in general thoracic surgery.

Postero-lateral thoracotomy has many complications such as postoperative pain, limitation in the motion of the shoulder, decreasing pulmonary function from immobilization, increasing lung atelectasis from over-use of analgesia, and increasing pulmonary morbidity, especially in elderly patients. So, muscle-sparing thoracotomy appears to be a good alternative. But it has also many disadvantages such as seroma and the needs for drains, limitation of an accessible operative field, and difficulties with risky procedures. We have modified muscle-sparing vertical thoracotomy. We performed 134 procedures on 131 patients from October 2000 to September 2003, including 15 cases of esophageal cancer, 95 cases of lung cancer, and 24 cases of other disease. Operative procedures were lobectomy in 74 cases, bilobectomy in 12 cases, pneumonectomy in 10 cases, wedge resection in 8 cases, decortication in 2 cases, Ivor Lewis procedure in 13 cases, and others in 15 cases. There was no occurrence of wound infection, arrrhythmia, fibrillation, and subcutaneous seroma except the first two cases. We had seven reoperations (two postoperative bleeding, three postpoperative BPF, one EGstomy leak, one RML torsion) and four operative mortalities (one postpneumonectomy BPF, two pneumonia, one heart failure). Our muscle-sparing vertical thoracotomy can be done safely in most thoracic surgery including lung and esophageal cancer, therefore it is a feasible procedure.