Average Occlusion Time Research Articles

Abstract No. 437 How much do fibers on embolic coils improve embolization efficiency?

Pushable embolic coils are manufactured in numerous styles and configurations. Fibered embolic coils remain the traditional mainstay in coil design. Yet, the impact of these fibers on embolization coils and how these fibers improve embolization are not well validated or studied. We aim to test the impact of these fibers utilizing the same detachable coil, with and without fibers using an animal swine model. Standard commercially available 0.035’ fibered coils were used; we specially acquired the same coils with the fibers removed. Occlusion efficiency was assessed by the number of coils used, unit length of coils, and the amount of time required for complete embolization. A total of 2 swine were used via a transfemoral approach. A total of 12 artery sites were embolized; matched 6 paired and similarly sized arteries (subclavian, inferior renal and internal femoral arteries). Each was subselected and embolized utilizing the same embolization protocol via a 5F JB1 catheter. Embolization was performed with detachable fibered coil on one side, and identical yet unfibered coil on the contralateral vessel. Standard clinical embolization practice and flow scoring (TIMI grading) was employed throughout. Average vessel size was similar for the fibered side (mean, 4.46 mm; range, 3.49-6.93 mm) vs non-fibered (mean, 4.74 mm; range, 3.33-66.9 mm). Average occlusion time was lowest for fibered coils with a mean time 7.16 min. vs 17.16 min in unfibered coils. Unit length coil used to achieve complete embolization was significantly less in fibered coil with a mean length of 28.3 cm (total, 170 cm) vs the unfibered which had a mean length of 60 cm (total, 360 cm). Fibered coils have a substantially improved embolization efficiency over those without fiber in the same coil design as measured by embolization time, number of coils used, and unit length of coil used in an animal model. These fibers directly reduce embolization time and number of coils required for complete embolization, which may translate into a reduction in procedure times and costs.

3:18 PM Abstract No. 304 How peripheral embolic coil design differences affect embolic efficacy

Embolic coils have been used for peripheral embolization since the 1970s with many commercially available designs. However, coil design differences relating to embolization efficacy is not well understood. We aim to test some of the variables used in commercially available coils, including coil size, fiber, fiber material, and expanding gel and compare how these differences affect embolic efficacy using a swine model. Paired arteries were selected and embolized utilizing 2 protocols. Standard clinical embolization practice and flow scoring (TIMI grading) was employed across the study. The first protocol contained two groups; Dacron fiber coil (Interlock 18 Bos. Sci.) vs. nylon/PGLA coil (Concerto Covidien) and Dacron fiber coil (Interlock 18) vs. hydrogel coil (Azur Terumo). Selected arteries fit predetermined size and configuration criteria. The second protocol contained a single group comparing fibered 0.018 coils vs. nonfibered (fibered & nonfibered interlock 18) and compared the effect on coil diameter (Interlock 18 vs. Interlock 35); similar single arteries were selected with three treatment areas. Paired arteries (3) were occluded in each animal and 6 sets were occluded for each group. Occlusion efficiency was assessed by the number of coils used, unit length of coils and the amount of time required for complete embolization. Average occlusion time was quickest for the Interlock 18 and 35, both at mean time of 10.7 min. The Interlock 18 used less coils (mean # of coils 2.9 vs 3.5) and unit length of coil (50.3 and 65.0 cm). The longest mean occlusion time was for the Azur at 19.4 mins and utilizing an average of 4.8 coils and 95.2 cm unit length. Most efficacious was Interlock 18, which was 47% better in embolization time and 48% better in mean coil length for complete embolization, than the least, the Azur. On average, coils with fiber had shorter occlusion time than those without (10.7 vs. 15.3 mins) and utilized less coils (2.9 vs. 4.2). Fibered coils, specifically Dacron fibers, have an improved embolization efficacy over those without fiber (and hydrogel) as measured by embolization time, number of coils, and unit length of coil used in an animal model.

New types of operation based on perihilar resection to cure hilar cholangiocarcinoma

Objective To explore clinical efficacy of new types of operation based on perihilar resection to cure hilar cholangiocarcinoma. Methods The retrospective descriptive study was conducted. The clinico-pathological data of 4 patients with different Bismuth type of hilar cholangiocarcinoma who were admitted to the Beijing Tsinghua Chunggung Hospital from December 2014 to June 2016 were collected. After preoperative examinations and evaluations, single perihilar resection or combined with central liver segmentectomy were performed. Observation indicators included: (1) intraoperative situations; (2) postoperative pathological examinations; (3) postoperative situations; (4) follow-up. Patients were followed up using outpatient examination up to June 2017. Follow-up included abdominal pain, fever, routine blood test, tumor marker test and imaging examination which detected tumor recurrence and metastasis. Measurement data were represented as average (range). Results (1) Intraoperative situations: 4 patients received successful operations, with an average operation time of 512 minutes (range, 300-620 minutes). Portal vein was blocked continuously, with an average occlusion time of 70 minutes (range, 57-80 minutes), an average volume of intraoperative blood loss was 537 mL (range, 200-1 000 mL). Two patients received transfusion of 2 U plasma, 4 U plasma + 4 U red blood cell (RBC), respectively. (2) Postoperative pathological examinations: results of postoperative pathological examinations in 4 patients showed that tumor size was respectively 1.5 cm×1.2 cm×1.1 cm, 1.3 cm×1.1 cm×1.0 cm, 2.0 cm×1.7 cm×1.5 cm and 2.0 cm×2.0 cm×1.5 cm. Tumor differentiation: 1 and 3 patients were respectively detected in moderate-differentiated cholangiocarcinoma and low-differentiated cholangiocarcinoma. Positive nerve plexus invasion was found in all 4 patients and 3 patients had regional lymph node metastasis. Four patients received R0 resection. TNM staging: T2aN1M0 and T2bN1M0 were found in 1 and 3 patients, respectively. (3) Postoperative situations: of 4 patients, 1 complicated with biliary leakage was cured by conservative treatment and then discharged from hospital at 67 days; 3 had good recovery and then discharged from hospital at day 21, 14 and 14, respectively. Patients didn′t receive postoperative adjuvant treatment, such as chemoradiotherapy. (4) Follow-up: 4 patients were followed up for 12-31 months. During follow-up, 4 patients were in good condition, and 1 with transient fever was relieved by conservative treatment. Levels of tumor marker in 4 patients were normal, results of enhanced CT scan showed no signs of tumor recurrence and intrahepatic bile duct dilatation. Conclusion After precisely evaluating the tumor extension among segmental bile duct, single perihilar resection or combined with central segmentectomy can effectively cure hilar cholangiocarcinoma. Key words: Biliary neoplasms, hilar; Perihilar resection; Segmental bile duct

All-on-4 occlusion study: using T-Scan Ⅲ occlusal analysis system

To investigate the occlusal force distribution and the characteristics of the occlusion time of patients with All-on-4 rehabilitation at different occlusion position using T-Scan Ⅲ occlusal analysis system. Thirteen volunteers with All-on-4 rehabilitation were included in this study. T-Scan Ⅲ occlusal analysis system was used to measure the occlusal force distribution and the time character of the patients at intercuspal position, protrusive position, and lateral excursive position. Maximum intercuspation: the left and right premolars took most of the occlusal force, namely (17.3±3.1)%, (15.8 ± 4.6)%, (15.5 ± 2.2)% and (15.2 ± 5.5)% (24, 25, 14, 15), the implants areas including the premolar and anterior teeth took (64.0±6.7)%, (19.2±8.0)% of occlusal force. The left and right sides took the respective percentages of (50.5±6.1)%, (49.5±6.1)%, and there was no difference. Protrusion position: the region (11, 12, 21, 22) commitment to take the percentage of (90.4±27.7)%. Occlusion time: 0.18(0.11, 0.26) s, disclusion time: 0.52 (0.35, 1.14) s . At the left and right lateral position, 8 patients were single teeth-supported occlusion, 5 patients were group fuctional occlusion, the average occlusion time was 0.20(0.13, 0.34) s, and DT was 1.07 (0.58, 1.46) s. At maximum intercuspation: the implants areas including the premolar and anterior teeth were the occlusal force centers; the force concentrated in the area (11, 12, 21, 22) at the protrusion position. The lateral occlusal pattern shows multiformity.

ASSA14-12-12 The analyses of incidence of failure and relate factors in patients with retrograde wire for the treatment of chronic coronary artery occlusion

<h3>Background</h3> To evaluate the incidence of failure and related factors in patients with regrograde wire technique for the treatment of chronic coronary artery occlusion. <h3>Methods</h3> The data of 170 CTO patients undergoing retrograde PCI for a CTO from August 2004 to October 2013.170 cases with chronic coronary artery occlusion underwent transcutaneous coronary artery intervention (PCI) therapy by retrograde wire technique were enrolled in this study (male: 97, mean age: 60.6 ± 11.3 years). Failure is defined as wire is unable to pass through the occlusion of the target – artery or retrograde wire is unable to find the collateral circulation of miraclechannel. And the procedure is failed in stent implantation. We assessed the plasticity and determinants of retrograde wire technique of PCI <h3>Results</h3> The data of 170 CTO patients undergoing retrograde PCI for a CTO from August 2004 to October 2013 were analysed. The average occlusion time lasts more than 3.3 years, including 70 LAD CTO and 88 RCA CTO. Retrograde wire technique was failued to performe in 26 patients with chronic coronary artery occlusion. The average of 26 patients were treated by 4.3 guidewires, 1.2 microcatheters and intravascular contrast media 210 ml. there were no significantly changes about left atrial (LA)diameter and and left ventricular (LV) ejection fraction (p &gt; 0.05) between success group and failue group. There were 26 patients (26/170, 15.2%) with at least one reason, including 17 cases with the wire is unable to pass through the collosion; 2 cases with small right coronary artery; 7 cases with bad collateral miraclechannel. In logistic regression analysis, the occlusion time between 3–12 months and whether the target artery had received antigrade wire technique before were the independent predictors of failure rate. <h3>Conclusions</h3> According to the data, the success rate of the occlusion time between 3–12 months is the lower than 1–3 years. There is no difference of the success rate between occlusion segment ≥15 mm and &lt;15 mm, which is different from the previous view. Retrograde wire technique significantly increases the success rate of procedure in patients who failed in antegrade wire technique.

Rapid Interruption Of Occlusive Thrombus Formation By The Protein C Activator Enzyme EWE Thrombin (ProCase) In Primates

A hemostatically safe antithrombotic treatment with rapid onset could significantly improve the chances for survival during acute thrombotic events such as heart attack and ischemic stroke. Current thrombolytic treatment with tissue plasminogen activator (tPA) is effective at halting and reversing the progression of arterial thrombi, but bleeding side-effects significantly limit its usefulness. EWE thrombin (ProCase) is an investigational selective protein C activator thrombin analog under development for treating acute thrombotic emergencies. We therefore tested the ability of EWE thrombin to interrupt arterial-type thrombus formation in baboons compared to a standard interventional dose of tPA (1mg/kg, iv). Thrombosis was initiated by interposing 2mm or 4mm internal diameter (ID) collagen coated ePTFE vascular grafts within an arterio/venous shunt. Platelet thrombus formation was monitored by gamma camera imaging of autologous 111In-labelled platelets for a total of 90 min in the 4mm grafts, or until occlusion time in the 2mm grafts. Fibrin deposition was determined by direct measurement of 125I-labelled fibrinogen. All interventions were given systemically, starting 30 min or 15 min after thrombus initiation for the 4mm grafts and 2mm grafts, respectively. In the 4mm devices, treatment with tPA reduced graft-associated platelet accumulation by 17% and fibrin deposition by 61% compared with controls (n=6 each). A negative platelet accumulation rate, which is an indication of thrombolysis, occurred between 40-50 min after initiating tPA treatment. EWE thrombin, at doses ranging from 2-10µg/kg iv bolus rapidly interrupted thrombus development and reduced platelet deposition by 43-65% (n=4). Fibrin deposition was also reduced by 36-49% compared with controls. A negative platelet accumulation rate occurred between 10-15 min after EWE thrombin treatment, compared with continuous platelet accumulation in all control experiments. In the 2mm ID grafts, 0/6 control group devices remained patent with an average occlusion time of 25±2 min. By comparison, EWE thrombin (10µg/kg iv bolus given at 15 min) successfully interrupted occlusive thrombus formation in 40% of the devices (2/5) during the 60 min study, and significantly prolonged the occlusion time to an average of 43±8 min. These data suggest that EWE thrombin can effectively interrupt occlusive arterial-type thrombus development at very low doses, and appears to be more effective and act more rapidly than tPA at limiting experimental platelet-rich thrombus accumulation. We conclude that EWE thrombin may be a more effective and safer alternative to tPA for treating acute thrombotic emergencies. Disclosures:Tucker:Aronora, Inc: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Wallisch:Aronora, Inc: Employment. Leung:Aronora, Inc: Employment, Equity Ownership. Gruber:Aronora, Inc.: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Verbout:Aronora, Inc: Employment, Equity Ownership.

Role of cellular senescence in the age‐associated risk of venous thrombosis

During normal aging, expression of the tumor‐suppressor gene, p16ink4a, results in cellular senescence in many tissues, including the vasculature. We hypothesize that p16ink4a‐mediated cellular senescence is associated with impaired hemostasis and contributes to a prothrombotic phenotype. In this study, we have used in vivo murine models of vascular injury to examine the role of p16ink4a and cellular senescence in venous thrombosis. Transgenic mice over‐expressing p16ink4a were developed and real‐time PCR data show a 6.5 fold increase in expression of p16ink4a in the saphenous vein/artery bundle. When challenged with an acute ferric chloride injury to the saphenous vein, the p16ink4a transgenic mice have a significantly shorter occlusion time when compared to wild‐type controls. Wild‐type mice show an average occlusion time of 20 minutes versus 13.5 minutes in the p16ink4a transgenic mice. Additional studies have shown that p16ink4a does not alter blood cell populations or venous flow velocity. Currently, we are examining the role of cellular senescence in the response to injury over time. Our results suggest the p16ink4a transgenic mice have a delayed response to injury and are more sensitive to damage induced by ferric chloride. Our studies with the transgenic p16ink4a mice are the beginning to our understanding the role of cellular senescence in the risk of venous thrombosis.NIH support 1R21AG031068‐01.

The significance of Chlamydia pneumoniae in symptomatic carotid stenosis.

An association between symptomatic carotid stenosis and recent infection with Chlamydia pneumoniae is reported. Thirty-five patients (20 symptomatic and 15 asymptomatic) with carotid stenosis of 70% to 90% underwent carotid endarterectomy. Endarterectomy was performed without patch and shunt; the average occlusion time of the internal carotid artery was 14 +/- 3 min. The atheromatic plaque and a portion of the thyroid artery were examined with polymerase chain reaction and peripheral vein blood was obtained for serologic detection of systematic infection, and IgG and IgM antibodies to C. pneumoniae by enzyme-linked immunosorbent assay. Twenty of 35 patients (57.1%) had increased titers of IgG antibodies to C. pneumoniae. Eight patients revealed IgG plus IgM antibodies; two of the eight had IgG, IgM, and positive findings on polymerase chain reaction. No C. pneumoniae was detected on the thyroid arteries. Sixty-five percent (13/20) of the patients with increased IgG antibodies to C. pneumoniae, 87.5% (7/8) with IgG + IgM, and 100% with IgG + IgM + positive polymerase chain reaction were symptomatic. Plaque morphology in association with symptoms did not reveal a significant correlation between soft plaques and symptoms, whereas the majority of the symptomatic patients had plaques of type III-V. Patients having recent contamination and positive polymerase chain reaction had a significant relationship between C. pneumoniae infection and symptomatic carotid disease. This supports the hypothesis that C. pneumoniae infection can produce a kind of instability of the carotid plaque. The results of this study demonstrate that patients with advanced atherosclerotic carotid disease have an increased incidence of C. pneumoniae infection. Recent infection could be responsible for instability of the carotid plaque, causing cerebral ischemic episodes.

Changes in ventricular repolarization during percutaneous transluminal coronary angioplasty in humans assessed by QT interval, QT dispersion and T vector loop morphology.

Based on clinical, epidemiological, and experimental data, transient cardiac ischaemia is one of the major triggering factors of malignant ventricular arrhythmia. According to animal studies, increased dispersion of repolarization is of pathophysiological relevance in this context. Therefore we explored the impact of myocardial ischaemia during single vessel coronary angioplasty on the change in ventricular repolarization, measured by QT and JT intervals and their dispersion in the 12-lead electrocardiogram. We also assessed a novel method, the 3-dimensional T vector loop, to find out whether it was sensitive to changes in ventricular repolarization during ischaemia, and whether there was any correlation with changes in the dispersion of the QT and/or JT intervals. This study was prospective with consecutive patients. Only patients in sinus rhythm and without bundle branch block were included. All coronary angioplasties were performed at Norrlands University Hospital, Umeå. The analysis of the material was performed at the Karolinska Hospital, Stockholm. Twenty-nine consecutive patients went through 30 elective one-vessel percutaneous transluminal coronary angioplasty (PTCA) procedures. PTCA was performed in 10 stenoses of the left anterior descending, 10 of the left circumflex, and 10 of the right coronary artery. A 12-lead electrocardiogram was recorded continuously as part of routine monitoring of the patient during PTCA and the T vector loop was calculated from the simultaneously recorded. X, Y, Z leads. Repolarization was assessed by the QRS, QT and JT intervals as well as by the T vector loop parameters (Tarea, Tavplan, and Teigenv) before and at the end of the first occlusion during PTCA. PTCA, with an average occlusion time of 171 +/- 60 s (mean +/- SD), induced ischaemia on the 12-lead electrocardiogram in 73% of cases. The overall response for the 30 procedures was a significantly increased dispersion of ventricular repolarization, both corrected and uncorrected for heart rate. QT dispersion increased by, on average, 19% from 74 +/- 35 to 88 +/- 36 ms, QTc dispersion by 27% from 71 +/- 39 to 90 +/- 42 ms, and JTc dispersion by 19% from 78 +/- 32 to 94 +/- 43 ms (P < 0.05). The T vector loop became more circular and bulgy during occlusion (all three parameters changed by between 33% and 59%). There was a significant correlation between changes in one of the T vector loop parameters (Teigenv), and changes in JT and QT dispersion in the left anterior descending group. Transient ischaemia during PTCA induced significant changes in ventricular repolarization, especially during occlusion of the left anterior descending artery and resulted in a significant increase in both QT and QTc dispersion. The degree of QT dispersion was such that several patients were at risk of ventricular arrhythmia, if a proper triggering extrasystole had occurred. In addition, and as an original observation, the 3-dimensional T vector loop morphology seemed even more sensitive to coronary occlusion than QT dispersion.

Recanalization of Thrombosed Dialysis Access with Use of a Rotating Mini-Pigtail Catheter: Follow-up Study

To evaluate the feasibility, efficacy, and safety of mechanical thrombectomy of occluded dialysis access with use of a rotating mini-pigtail catheter. Thrombus was fragmented by mechanical action of the rotating pigtail tip (5-mm diameter), while the guide wire exited a sidehole at the pigtail curvature and served as a fixed rotation axis. Twenty-six procedures were performed in 22 patients (12 men, 10 women; mean age, 55.5 years). Native fistulas were treated in 15 instances, polytetrafluoroethylene (PTFE) grafts were treated in 11 instances. Average occlusion time was 20 hours +/- 13 (range, 5-46 hours), average occlusion length was 25.6 cm +/- 10.1 (range, 6-45 cm). Thrombus fragmentation was followed by balloon angioplasty of underlying stenoses. In all 26 procedures, the dialysis access was successfully declotted with subsequent dialysis using the access (clinical success rate, 100%). Handling of the mini-pigtail catheter was simple and rapid, regardless of whether a graft or a native fistula was treated. Average duration of the intervention was 118 minutes +/- 30. Mean primary patency was 165 days +/- 167. Primary patency rate was 82% at 30 days, 65% at 3 months, and 47% at 6 months. There was no evidence of complications due to the thrombus fragmentation procedure. The results suggest that declotting of occluded dialysis grafts and fistulas with the mini-pigtail catheter is as effective and safe as other more established percutaneous therapies. It may serve as an easy-to-handle, low-budget alternative to current thrombectomy devices.

Ruptured giant intracranial aneurysms. Part II. A retrospective analysis of timing and outcome of surgical treatment.

This retrospective study was made to determine the relationship between surgical timing and outcome in all patients with ruptured giant intracranial aneurysms undergoing surgical treatment at the Mayo Clinic between 1973 and 1996. The authors studied 109 patients, 102 of whom were referred from other medical centers. The ruptured giant aneurysms were 25 to 60 mm in diameter. One hundred five of the patients survived the rupturing of the aneurysm to undergo operation, with direct surgery possible in 84% of cases. Excluding delayed referrals, the average time to surgery after admission to the Mayo Clinic was approximately 4 to 5 days. Patients admitted earlier tended to be in poorer condition, often undergoing earlier operation. On average, surgical treatment was administered later for patients with ruptured aneurysms of the posterior circulation than for those with aneurysms in the anterior circulation. Temporary occlusion of the parent vessel was necessary in 67% of direct procedures, with an average occlusion time of 15.5 minutes. Among surgically treated patients, a favorable outcome was achieved in 72% harboring ruptured anterior circulation aneurysms and in 78% with ruptured posterior circulation lesions. The overall management mortality rate was 21.1%, and the mortality rate for surgical management was 8.6%. The authors believe that because of the technical difficulties and risk of rebleeding associated with ruptured giant intracranial aneurysms, timely referral to and well-planned treatment at medical centers specializing in management of these lesions are essential to effect a more favorable outcome.

Carotid endarterectomy without a shunt for symptomatic lesions associated with contralateral severe stensosis or occlusion

The purpose of this study was to assess the adequacy of thiopental protection against ischemic cerebral damage in patients undergoing carotid endarterectomy for symptomatic stenosis greater than 70% in association with contralateral stenosis greater than 70% or contralateral occlusion. All patients (n=259) with severe bilateral carotid disease who underwent carotid endarterectomy for symptomatic stenosis greater than 70% were extracted from the database of an ongoing prospective carotid surgery study. Large-dose thiopental sodium without shunting was used for cerebral protection during endarterectomy. Asymmetric electroencephalogram changes during the operation, carotid occlusion time, stroke onset, and neuropathologic outcomes were analyzed. Three contralateral strokes occurred in the series, producing a cerebral morbidity/mortality rate of 1.2% (major 0.4%, minor 0.8%). Transient morbidity was 1.9% made of two reversible ischemic neurologic deficits and three transient ischemic attacks. New asymmetric electroencephalography changes were seen in 49 (19% patients, one of whom had transient deficit. Average occlusion time was 35 minutes. All strokes occurred within 24 hours of the procedure. Patients with previous stroke and and systemic hypertension seemed at greatest risk, and the contralateral hemisphere was the area at greatest risk. All transient deficits were ipsilateral and related to technical complications rather failed protection. Thiopental cerebral protection eliminates strokes caused by complications of shunting, prevents ischemic stroke during carotid occlusion for periods up to 67 minutes (average 35 minutes), allows meticulous management of the operative site, may modify or minimize clinical neurologic deficit, and in our experience has rendered intraluminal shunting obsolete.

Anatomical study of the cavernous sinus emphasizing operative approaches and related vascular and neural reconstruction.

The efficacy of three operative approaches to the cavernous sinus (CS) and the possibilities of vascular and cranial nerve reconstruction in and around the CS were studied in 50 cadaver specimens (25 heads). The lateral operative approach was through the lateral wall, between Cranial Nerves V1 and IV, or between Cranial Nerves V1 and V2. The superior approach was through the superior wall of the CS after removing the anterior clinoid process and unroofing the optic canal. The inferior approach followed the petrous internal carotid artery (ICA) into the CS after an extradural subtemporal exposure or after a combined subtemporal and infratemporal fossa exposure. The different exposures of the spaces of the CS and of the intracavernous structures provided by the superior and the lateral approaches were complementary. The exposure provided by the inferior approach was minimal; however, the junction of the petrous and cavernous ICA was best exposed by this route. The combined subtemporal and infratemporal fossa approach exposed the petrous ICA (for proximal control or for reconstruction) with the greatest ease and with the least temporal lobe retraction. The combination of the superior and lateral approaches and the complete mobilization of the intracavernous ICA facilitated its repair after experimental lacerations. Lacerations of either the inferior and the inferomedial aspects of any portion of the cavernous ICA or of the anterior surface of the posterior vertical segment of the artery were the most difficult to repair. End-to-end anastomosis was more difficult with the posterior third of the artery than with the anterior two-thirds. A vein graft with an average length of 3.5 cm could be sutured from the petrous to the supraclinoid ICA to bypass the cavernous ICA, with an average occlusion time of 45 minutes. End-to-end technique was judged better for the proximal anastomosis, but end (graft)-to-side anastomosis was easier to perform at the distal end because of the location of the ophthalmic artery. Resuture of Cranial Nerves III and VI could not be performed in fresh cadavers if the gap exceeded 0.3 cm. In 3 specimens, the exposure of Cranial Nerve VI in the posterior fossa through the petrous apex and in the orbital apex was followed by graft placement (bypassing the CS). The complex anatomy of the cranial nerves at the apex of the CS was also defined in 10 specimens. Surgeons who perform operations in and around the CS for neoplastic and vascular lesions will find these studies useful.

Oral verapamil for prophylaxis of supraventricular tachycardia after myocardial revascularization: A randomized trial

To determine if the prophylactic administration of oral verapamil is effective in reducing the incidence of supraventricular tachycardia after myocardial revascularization, 141 patients were entered into a double-blind randomized trial. Seventy patients received verapamil 80 mg every 8 hours beginning immediately after operation and continuing for 5 days, and 71 patients received placebo. Patients were monitored during the study period and observed for the occurrence of supraventricular tachycardia. The verapamil and placebo groups were similar with regard to sex, age, preoperative antianginal drugs, number of bypass grafts, average bypass time, and average occlusion time. A total of 39 patients had supraventricular tachycardia, 20 were receiving verapamil, and 19 were receiving placebo. The average ventricular rate was 127 +/- 13 beats/min for the verapamil group with supraventricular tachycardia compared with 140 +/- 12 beats/min for the placebo group with the mean differences not significant (p = 0.10). On the basis of these data, it is concluded that verapamil 80 mg every 8 hours beginning early after myocardial revascularization is not effective in reducing the incidence of supraventricular tachycardia.

Aspirin and the Prevention of Experimental Arterial Thrombosis: Difficulty in Establishing Unequivocal Effectiveness

A trial of the efficacy of aspirin in the prevention of thrombotic occlusion of an "aortic loop" in rats was made simultaneously by two experimental surgeons. A relatively large dose of aspirin (80-100 mg/kg/day) was used, starting two days before operation. It appeared that aspirin was of limited benefit, reducing thrombotic occlusions by about 17% seven days after the insertion of the loop into the abdominal aorta. Although the average occlusion time was prolonged by about 17% in aspirin-treated animals, the separate trials gave no conclusive result. When the data from both operators were pooled, a statistically significant protection by aspirin was apparent (p = 0.02), by a two-tailed Student's t test. However, on using the powerful non-parametric randomization test, the occlusion times in control and aspirin-treated groups appeared not statistically different (p = 0.07). No significant difference was also found between control and treated groups when data were analyzed by X2 test. Independently of the statistical analysis, these data are quite similar to those obtained from aspirin trials in men surviving myocardial infarction. This finding points to the usefulness of the aorta loop as an animal model for arterial thrombosis.

A simple method of orthotopic liver transplantation in dogs.

Orthotopic liver transplantations were performed by one team in 18 dogs using a cuff method to anastomose the portal vein, the suprahepatic vena cava and the infrahepatic vena cava without external or internal shunts. Total and warm ischemic times of donor liver averaged 124 and 32 minutes, respectively. The average occlusion time of the portal vein and the infrahepatic vena cava were 9.7 and 13.9 minutes, respectively. During this time, uncontrolled hypotension, petechiae or hemorrhagic enterogastritis did not develop. Sixteen of 18 dogs survived more than five days, and five dogs lived more than three weeks. The cause of death was not related to the cuff method in any instance. This approach proved to be a technically simple and satisfactory procedure.

RETURN OF RENAL FUNCTION AFTER VARYING PERIODS OF URETERAL OCCLUSION.A CLINICAL STUDY.

Pelvic exenteration with diversion of both ureters was performed in 40 patients with advanced pelvic cancer and one ureter occluded on preoperative intravenous pyelograms (IVP). In 29 instances, renal function returned. Preoperative periods of occlusion were not always determinable; where they were, the average occlusion time followed by functional return was three to four months. Among those that did not show functional return, the average estimated occlusion time was 7 1/2 months. In 11 patients who had preoperative IVP over varying periods, it was possible to fix rather accurately dates of complete ureteral occlusion. There was return of function in seven patients with periods of occlusion varying from two to four weeks, and in one patient with 3 1/2 months occlusion. In two patients with occlusion. for 165 days, impaired function returned. In one patient with 100 days occlusion, function returned slowly and remained impaired.