Dissection Membrane Research Articles

Color Doppler ultrasonography is a reliable diagnostic tool in the diagnosis of extracranial vertebral artery dissections.

The purpose of this study was to evaluate the role of color Doppler sonography (CDS) in the diagnosis of extracranial vertebral artery dissections (EVADs). One hundred and fifty consecutive patients (age range 21-51years, mean 44years) with a clinical suspicion of vertebral artery dissection (VAD) were included in this study. All patients underwent CDS of vertebral arteries as the first-line imaging modality. Cervical T1-weighted fat-saturated axial MR images served as the gold standard. Of the 150 patients with a clinical suspicion of VAD, 27 patients were ultimately diagnosed with EVADs based on fat-saturated T1-weighted MR imaging. MR imaging was considered positive when crescentic hyperintensity (methemoglobin signal) was demonstrated at the wall of the vertebral artery. CDS was positive in 21 of these 27 patients and revealed either intramural hematoma or a dissecting membrane with two lumina. The most frequent site of involvement was the V1 to proximal V2 segment. The sensitivity, specificity, and positive and negative predictive values of CDS in the diagnosis of EVADs were 77.8, 98.4, 91.3, and 95.3%, respectively. CDS is a reliable diagnostic tool in the diagnosis of EVADs.

Anomaly of Haughton type D left cervical aortic arch in combination with type B dissection: case report and literature review

BackgroundThe anomaly of cervical aortic arch is a rare phenomenon first described by Reid in 1914 and categorized by Haughton in 1975. The left cervical aortic arch Type D consisting of an ipsilateral descending aorta and coarctation or aneurysmatic formation of the arch demonstrates a complicated form requiring surgical management. Because of its rarity and unspecific symptoms only few cases are documented with the focus on surgical management.Case presentationA 43-year old, asymptomatic woman presented with a mediastinal mass overlapping the aortic arch region in a routine x-ray. For verification, a computed tomography was performed and revealed incidentally a type B dissection originating from an aneurysm of a left cervical arch with a maximum diameter of 6 cm. Because of the huge diameter and the potential risk of rupture, an urgent surgical repair was planned. Surgical access was performed through median sternotomy and an additional left lateral thoracic incision through the fourth intercostal space. Simultaneously to the preparation, partial cardiopulmonary bypass was installed in the left groin. After preparation of the recurrent and phrenic nerve and the supraaortic branches, the descending aorta was clamped. Before the distal anastomosis to a straight graft, we performed a fenestration of the dissection membrane about a length of 5 cm to preserve the perfusion of both lumina. Then, the straight graft was sutured to the proximal part of descending aorta. The left axillary artery originated directly from the aneurysm and was dissected and reimplanted with a separate 8 mm sidegraft to the straight graft between the distal arch and proximal descending aorta. The patient was extubated on first postoperative day and recovered well.ConclusionThe left cervical aortic arch type D is a rare disease, which is prone to aneurysm formation due to abnormal flow patterns and tortuosity of the aorta. The difficulty lays in the identification of the pathology, especially in the physical examination, since a pulsating mass or cervical murmur seem to be the most specific symptoms in the majority of young, female patients. If diagnosed, surgical therapy with resection of the aneurysm and reimplantation of the axillary artery under cardiopulmonary bypass demonstrates the treatment of choice.

Techniques and outcomes of false lumen embolization in chronic type B aortic dissection

Endovascular strategies have been increasingly used for the treatment of chronic type B aortic dissection (cTBAD) offering better outcomes in terms of mortality and morbidity compared to open surgical repair. Aortic remodeling after standard TEVAR is less likely in cTBAD due to rigidity of the dissection membrane. Another limitation of endovascular therapy is continued retrograde false lumen perfusion with back-flow from distal entry tears. Treatment strategies in cTBAD should aim at false lumen thrombosis. There are many approaches to achieve this goal of false lumen thrombosis, but concepts as open surgery or fenestrated and branched endovascular repair are limited by either high technical and logistic demands to the surgeon or high rates of mortality and morbidity. False lumen embolization techniques offer less invasive treatment strategies with promising early results. The main strategies for false lumen embolization include the "cork in the bottle neck" technique, the Candy-Plug technique or the Knickerbocker-technique. This article describes technical aspects and early results of these new endovascular techniques of false lumen embolization in chronic aortic dissection.

Visual Three-Dimensional Reconstruction of Aortic Dissection Based on Medical CT Images

With the rapid development of CT technology, especially the higher resolution of CT machine and a sharp increase in the amount of slices, to extract and three-dimensionally display aortic dissection from the huge medical image data became a challenging task. In this paper, active shape model combined with spatial continuity was adopted to realize automatic reconstruction of aortic dissection. First, we marked aortic feature points from big data sample library and registered training samples to build a statistical model. Meanwhile, gray vectors were sampled by utilizing square matrix, which set the landmarks as the center. Posture parameters of the initial shape were automatically adjusted by the method of spatial continuity between CT sequences. The contrast experiment proved that the proposed algorithm could realize accurate aorta segmentation without selecting the interested region, and it had higher accuracy than GVF snake algorithm (93.29% versus 87.54% on aortic arch, 94.30% versus 89.25% on descending aorta). Aortic dissection membrane was extracted via Hessian matrix and Bayesian theory. Finally, the three-dimensional visualization of the aortic dissection was completed by volume rendering based on the ray casting method to assist the doctors in clinical diagnosis, which contributed to improving the success rate of the operations.

Single dose intratympanic mesna application inhibits propylene glycol induced cholesteatoma formation.

Mesna (i.e. sodium 2-mercaptoethanesulfonate; C2H5NaO3S2) has been used in otological surgery such as cholesteatoma dissection and tympanic membrane lateralisation in atelectatic ears. However, this study aimed to investigate its effect on cholesteatoma formation. A total of 20 Wistar rats were divided into two groups of 10 animals. The right and left ears of control animals were treated with saline (saline control group; n = 10 ears) and propylene glycol plus saline (propylene glycol control group; n = 10 ears), respectively. In the mesna group, both ears were treated with propylene glycol plus mesna (n = 20 ears). On days 1, 8 and 15, the saline control group had intratympanic injections of 0.2 ml saline and the propylene glycol control and mesna groups had intratympanic injections of 0.2 ml 100 per cent propylene glycol. On day 22, the propylene glycol control group had a single intratympanic injection of 0.2 ml saline and the mesna group had a single intratympanic injection of 10 per cent mesna. Animals were killed 12 weeks after the last injection and the temporal bones were sent for histopathological evaluation. The cholesteatoma formation rate was 88 per cent in the propylene glycol control group, but was significantly lower in the mesna group (p = 0.01). There were no significant differences in granulation tissue formation (p = 0.498), cyst formation in the bulla (p = 0.381), fibrosis (p = 0.072) and epithelial hyperplasia (p = 0.081) among experimental groups. Intratympanic propylene glycol administration is an effective method of promoting experimental cholesteatoma formation. Administration of a single dose of intratympanic mesna inhibited cholesteatoma formation in an animal model.

Aortic dissection: medical, interventional and surgical management

### Learning objectives After reading this article, the readers should be able to: Acute aortic dissection (AAD) is a relatively rare but much-feared clinical presentation which has a high mortality,...

Postoperative Changes in the Distal Residual Aorta after Surgery for Acute Type A Aortic Dissection: Impact of False Lumen Patency and Size of Descending Aorta.

Objective In the present study, we retrospectively identified and analyzed the factors that influenced progressive dilatation of the residual distal aorta after surgical repair for acute type A aortic dissection (acute type A). Methods A total of 477 patients underwent surgical repair for acute type A aortic dissection between 1995 and 2012. Postoperative and follow-up computed tomography (CT) scans of the descending aorta were available in 105 patients. We analyzed the maximum aortic diameter, total luminal area, and true luminal area of the descending thoracic and abdominal aorta. Results The mean follow-up time was 4.5 ± 3 years, and the mean time interval between CT scan investigations was 2.0 ± 2.3 years. A residual dissection membrane was observed in 80 (76%) patients, with presence of a patent false lumen (FL) in 52 patients (50%) and a thrombosed FL in 28 patients (26%).Progression of aortic disease with an increase in aortic diameter greater than 10 mm was observed in 14.3% (n = 15) of patients during follow-up. The independent predictors that influenced progressive dilation of the descending aorta by 10 mm or more were postoperative descending aortic diameter greater than 40 mm (p = 0.006; odds ratio [OR], 5.6; 95% confidence interval [CI], 1.6-19) and postoperative patent FL (p = 0.002; OR, 8.5; 95% CI, 2.2-32.3).The unadjusted 1- and 5-year freedom from reoperation was 96.9 ± 2 and 80.1 ± 5%, respectively. Marfan syndrome (p = 0.006; OR, 5.2; 95% CI, 1.6-16.9) and postoperative descending aortic diameter greater than 40 mm (p = 0.07; OR, 4.1; 95% CI, 1.4-11.6) were independent predictors of aorta-related reoperations.The mean survival at 1, 5, and 8 years was 90.7 ± 3, 82.5 ± 4, and 70 ± 6%, respectively. Previous cardiac surgery was independent predictor of midterm survival (hazard ratio, 3.6; 95% CI, 1.03-2.8; p = 0.04). Conclusions A regular follow-up CT scan is mandatory to assess progressive dilatation of the distal residual aortic arch, descending thoracic, and abdominal aorta after surgical repair of acute type A dissection, particularly in patients with a patent FL, descending aortic diameter greater than 40 mm, and/or Marfan syndrome.

Improved visual delineation of the intimal flap in Stanford type A and B dissections at 3rd generation dual-source high-pitch CT angiography.

Evaluation of the intimal flap visibility comparing 2nd and 3rd generation dual-source high-pitch CT. Twenty-five consecutive patients with aortic dissection underwent CT angiography on a second and third generation dual-source CT scanner using prospective ECG-gated high-pitch dual-source CT acquisition mode. Contrast material, saline flush and flow rate were kept equal for optimum comparability. The visibility of the intimal flap as well as the delineation of the different vascular structures was evaluated. In 3rd generation dual-source high-pitch CT we could show a significant improvement of intimal flap visibility in aortic dissection. Especially, the far end of the dissection membrane could be better evaluated in 3rd generation high-pitch CT, reaching statistical significance (P<0.01). 3rd Generation high-pitch CT angiography shows a better delineation of the aortic intimal flap in a small patient cohort, especially in the far ends of the dissection membrane. This might be due to higher tube power in this CT generation. However, to generalise these findings larger trials are needed.

Type A aortic dissection model to improve endovascular research and technologies.

Type A aortic dissection is a life-threatening disease requiring immediate surgical treatment. With emerging catheter-based technologies, endovascular stent-graft implantation to treat aneurysms and dissections has become a standardized procedure. However, endovascular treatment of the ascending aorta remains challenging. Thus we designed an ascending aortic dissection model to allow simulation of endovascular treatment. Five formalin-fixed human aortas were prepared. The ascending aorta was opened semicircularly in the middle portion and the medial layer was separated from the intima. The intimal tube was readapted using running monofilament sutures. The preparations were assessed by 128-slice computed tomography. A bare-metal stent was implanted for thoracic endovascular aortic repair in 4 of the aortic dissection models. Separation of the intimal and medial layer of the aorta was considered to be sufficient because computed tomography showed a clear image of the dissection membrane in each aorta. The dissection was located 3.9 ± 1.4 cm proximally from the aortic annulus, with a length of 4.6 ± 0.9 cm. Before stent implantation, the mean distance from the intimal flap to the aortic wall was measured as 0.63 ± 0.163 cm in the ascending aorta. After stent implantation, this distance decreased to 0.26 ± 0.12 cm. This model of aortic dissection of the ascending human aorta was reproducible with a comparable pathological and morphological appearance. The technique and model can be used to evaluate new stent-graft technologies to treat type A dissection and facilitate training for surgeons.

Open aortic arch surgery in chronic dissection with visceral arteries originating from different lumens.

Surgical management of chronic aortic dissection is controversial, especially when the dissection extends into the abdominal aorta in which the visceral arteries originate from different lumens and is combined with aortic arch pathology necessitating surgery. The aim of the study was to evaluate the results of open surgery in this complex aortic pathology. Between June 2002 and 2015, a total of 17 patients (median age 57, range 32-76 years) necessitating complete arch replacement presented complex chronic dissection of the thoraco-abdominal aorta with the visceral arteries originating from different lumens. Fourteen patients (82%) had had previous cardiac surgery, which was performed on the proximal aorta in all but one because of acute type A dissection. Nine patients without considerable dilatation of the descending aorta received aortic arch replacement with distal resection of the dissection membrane, and 8 patients with progressive dilatation of the thoracic aorta underwent aortic arch and descending aorta replacement via clamshell approach. No early (defined as 30-day, 90-day and in-hospital period) deaths, strokes or spinal cord injuries occurred. Only 1 patient (6%) presented temporary neurological dysfunctions (delirium, agitation), which resolved completely before discharge, and an injury of the recurrent laryngeal nerve was documented in 2 patients (12%). Temporary dialysis was necessary in 1 case. The follow-up was complete for all patients. All but one patient, who died due to leukaemia 23 months after surgery, were alive at the last follow-up (median duration 33 months, range 2-118 months). No patient needed a reoperation or an intervention on the thoracic and/or abdominal aorta. Moreover, no noticeable progression of the chronic dissection in the downstream aorta was documented in any patient. The results after conventional aortic arch repair with distal resection of the dissection membrane and, if necessary, with replacement of the progressively dilated chronic dissected thoracic aorta can offer excellent results in experienced hands and, therefore, this technique may be considered as a preferable option for surgical treatment of chronic aortic dissection with involvement of the aortic arch and the visceral arteries originating from different lumens.

Addressing Persistent False Lumen Flow in Chronic Aortic Dissection: The Knickerbocker Technique

To describe an innovative technique to occlude distal backflow into a false lumen aneurysm by controlled rupture of the dissection membrane after stent-graft implantation. The "Knickerbocker technique" involves relining the true lumen in the descending aorta with an oversized thoracic tubular endograft, followed by controlled rupture of the dissection membrane using a large compliant balloon within the graft's midsection. This maneuver, which allows expansion of the stent-graft's midsection into the false lumen, was developed in order to occlude the large false lumen distally and thus prevent continued false lumen perfusion through distal abdominal entry tears. The technique has been successfully used in 3 patients with ruptured or symptomatic chronic false lumen aneurysm in type B aortic dissection. There was no short-term mortality associated with the procedure. After a mean follow-up of 8 months, the false lumen aneurysm remained thrombosed, with no mortality after a mean clinical follow-up of 22 months. The Knickerbocker technique appears to be feasible and effective in inducing false lumen thrombosis in selected patients who undergo stent-grafting for chronic type B aortic dissection.

Acute respiratory failure due to giant aortic aneurysm mimicking massive pulmonary embolism in a patient with Marfan’s syndrome

A 41-year-old male with Marfan’s syndrome was admitted to the emergency department with severe dyspnoea. On his medical history, an operation of tube graft interposition to ascending aorta and aortic valve replacement ten years ago was remarkable. On physical examination, respiratory sound was almost inaudible on the left side of the chest. Cardiac auscultation revealed a grade 2/6 systolic murmur on the left 4th to 6th intercostal spaces. His pulse rate was 108 bpm and blood pressures were measured as 112/73 and 124/82 mm Hg in the left and right arm, respectively. The patient’s neck veins were distended. From the analysis of arterial blood gas on 10 L/min oxygen inhalation, pH 7.45, PaCO2 67 mm Hg, PaO2 71 mm Hg, SaO2 80%, and HCO3 – 20.1 mmol/L were obtained. A chest X-ray revealed widening of the mediastinum and collapsed left lung (Fig. 1). Transthoracic echocardiography revealed mitral valve prolapses, moderate degree of mitral regurgitation, normal left ventricular systolic function (LVEF 60%) and normal functioning of prosthetic aortic valve and significant dilatation and dissection of the descending aorta (Fig. 2). Aortic angiography by computed tomography (CTA) displayed the dissection and dilatation of the descending aorta accompanied by a thrombosed false lumen (Fig. 3A). Dissection membrane was extending from the origin of the left subclavian artery to the right iliac artery and was causing the compression of the left lung and right pulmonary artery (Fig. 3B). The patient was intubated and transferred to the intensive care unit. Unfortunately he died because of acutely developed progressive renal failure, cardiac and pulmonary failure complicated by lung infections over the subsequent ten days. In patients with Marfan’s syndrome, the risk of aortic dissection is approximately 1%. Aortic dissection is a tear within the layers of the aortic wall and the separation of them. An aortic aneurysm may present with symptoms of compression due to mass effect to the adjacent organs. Although the thoracic aorta is a close neighbour to the bronchus, pulmonary atelectasis and obstruction of the pulmonary artery due to an aortic aneurysm is uncommon. In our case, a giant thoracic aortic aneurysm had reached a large enough size to cause left sided collapse of the lung. Collapsed pulmonary volume and decreased aeration was complicated by oxygen and carbon dioxide exchange and led to hypercapnia and inability to respiratory compensation of acidosis induced by acute renal failure due to aortic dissection. Also, compression of the contralateral right pulmonary artery reduced the perfusion and aggravated the scenario.

The most versatile and useful appendage on earth

At first glance, this paper by Shrestha et al. [1] is a standard analysis and evaluation of a single-centre experience using the elephant trunk technique for total arch replacement. About one-third of the operations were followed by a second-stage procedure, mostly a descending thoracic replacement, only in 11 cases by a thoracoabdominal repair. The focus of this paper clearly lies in the first surgical step. When studying this paper more thoroughly, it becomes obvious that it is not just an average description and common analysis of the surgical results as we can find almost monthly in all wellrespected cardiovascular journals. It is much more than that. It is a wonderful piece of history describing the evolution of the elephant trunk technique starting with its introduction three decades ago by its inventor Hans Borst. Needless to say that the idea of inserting a free-floating vascular prosthesis into the downstream aorta and that in doing so, avoid re-entering in a surgical field that is crowded with major vascular, bronchial, neurological, lymphatic and gastrointestinal structures almost merits the Nobel prize in cardiovascular surgery, if it existed. Technical modifications were later introduced by some outstanding pioneers in cardiovascular surgery (such as Crawford and Svensson) in order to facilitate the technique and to reduce complication rate. Very often, these modifications were just simplifications, which is of course characteristic of the influence of great surgeons. Of special importance are the alterations concerning cerebral protection: for 17 years, deep hypothermic circulatory arrest was the mainstay and in 1999 antegrade selective cerebral perfusion was introduced and is actually a main pillar to success. It is not a coincidence that this paper now originates from the cradle where the elephant trunk was born. If you do not possess an atlas of cardiovascular surgery, this paper will tell you the ins and outs based on the evolution of the surgical technique. For example, how you can avoid trunk impaction, how to deal with the dissection membrane in chronic situations, what should be the optimal length of the trunk, how to avoid left recurrent nerve damage .... These are all fundamental aspects that should be respected in order to obtain optimal results. Concerning these results, it should be stressed that 25% of the patients received the elephant trunk for an acute Type A dissection. Very few of us are able to perform this under these dangerous circumstances. Moreover, 30% were redos. It is obvious that these two items certainly have influenced the outcome in a negative way. Another important point that had a major impact on the results was the learning curve. As the evolution of the elephant and its trunk took millions of years, we may not expect that the surgical technique can be made perfect in 30. That is why the results should be interpreted with caution and be seen in perspective. For an elephant, its trunk is absolutely vital and indispensable; without the elephant trunk technique, no matter in which form, cardiovascular surgery certainly would loose tremendous allures and look massively different.

Influence of operative strategy for the aortic arch in DeBakey type I aortic dissection - analysis of the German Registry for Acute Aortic Dissection type A (GERAADA).

Acute aortic dissection type A (AADA) remains a life threatening medical condition requiring emergent surgical therapy. Despite improvements in diagnostics, medical therapy and surgical technique, patient mortality and morbidity remains high (1). Standard treatment in the setting of AADA is the replacement of the ascending aorta with resection of the entry site, often in combination with an open distal anastomosis or hemiarch replacement, during a period of circulatory arrest with implementation of adjunct neuroprotective strategies such as cerebral perfusion and hypothermia (2). However, this treatment leaves the downstream aorta untouched and a residual dissection membrane remains in up to 70% of patients treated for AADA (3-7). The risk of progressive dilation with possible need for aortic re-intervention over the long-term remains (8-11). Due to this risk, a more aggressive approach with complete arch replacement and possible stenting of the proximal descending aorta via an antegrade approach has been adopted by a number of clinical institutions worldwide, to better obliterate the false lumen and thus reduce the incidence of late aortic complications (12-14). Other groups, however, have demonstrated an increased risk of mortality and morbidity when extensive surgery involving the aortic arch and the downstream aorta is implemented, thus recommending a more conservative approach to the treatment of AADA patients (15,16). The German Registry for Acute Aortic Dissection type A (GERAADA) is a web-based registry, initiated by the Working Group for Aortic Surgery and Interventional Vascular Surgery of the German Society for Thoracic and Cardiovascular Surgery. It is presently the largest registry worldwide documenting patients undergoing surgery for AADA (17-19). Analysis of GERAADA gave us the opportunity to compare the surgical outcomes of patients with DeBakey type I dissection treated by total arch replacement and those of hemiarch replacement with respect to early mortality, and onset of new neurological and malperfusion deficit.

Imaging and Quantitation Techniques for Tracking Cargo along Endosome-to-Golgi Transport Pathways.

Recent improvements in the resolution of light microscopy, coupled with the development of a range of fluorescent-based probes, have provided new approaches to dissecting membrane domains and the regulation of membrane trafficking. Here, we review these advances, as well as highlight developments in quantitative image analysis and novel unbiased analytical approaches to quantitate protein localization. The application of these approaches to endosomal sorting and endosome-to-Golgi transport is discussed.

A Rare Pattern of Acute Type A Aortic Dissection: Circumferential Intimal Invagination

A 59-year-old patient with chest pain was transferred to our emergency unit. Computed tomography depicted a dissection membrane limited to the aortic root and a seemingly normal ascending aorta. Further downstream stenosis of the descending aorta appeared. Intraoperatively, complete intimal absence in the ascending aorta with intussusception into the descending aorta was evident. Ascending aortic and hemiarch replacement was performed. This rare case should raise the surgeons' awareness that preoperative imaging can differ considerably from intraoperative findings.

Extent II repair of thoracoabdominal aortic aneurysm secondary to chronic dissection.

Crawford extent II thoracoabdominal aortic aneurysm (TAAA) repairs generally involve replacing the full length of the thoracoabdominal aorta, from the left subclavian artery to the infrarenal abdominal aortic bifurcation, with a synthetic graft. Because of the extensive degree of aortic replacement involved, extent II repairs have been associated with the highest levels of risk for postoperative complications (1-6). To mitigate these complications, we routinely employ a multimodal approach to organ protection during these operations (7-9). To protect the spinal cord, we use mild passive hypothermia, cerebrospinal fluid drainage, left heart bypass (LHB), sequential cross-clamping, and selective reimplantation of intercostal or lumbar arteries (7,8,10,11). We intermittently deliver cold crystalloid solution to the kidneys to protect them from ischemic damage and prevent acute renal failure (12-14). We also deliver isothermic blood from the LHB circuit to the celiac axis and the superior mesenteric artery (SMA) to minimize ischemic times for the abdominal organs. To illustrate our technique for performing extent II TAAA repair, we present a video (Video 1) of such a procedure performed in a 55-year-old man with a symptomatic TAAA associated with chronic DeBakey type III aortic dissection (Figure 1). The patient had a history of hypertension, smoking, hepatitis B and C, and hepatic cirrhosis, as well as cocaine abuse, which is a risk factor for aortic dissection (15). At the time of his referral for surgical treatment, the patient was experiencing intermittent back pain. Preoperative imaging revealed a relatively normal-sized aortic arch with a dissection membrane starting just distal to the left subclavian artery. The true lumen was narrow, and the dissection extended into the celiac axis. The aneurysm measured 6 cm in diameter, and there was a large burden of thrombus in the infrarenal region. Open in a separate window Figure 1 Preoperative anatomy. Illustration and sections from a computed tomography scan showing the patient’s thoracoabdominal aortic aneurysm, which was associated with chronic aortic dissection. Note the narrow true lumen (double arrows) and the extension of the dissection into the celiac axis (single white arrow). The aneurysm begins to taper in the infrarenal region. Used with the permission of Baylor College of Medicine

Retrograde Recanalization Technique for Use After Failed Antegrade Angioplasty in Chronic Femoral Artery Occlusions

To describe a technique to approach chronic total occlusions (CTOs) of the superficial femoral artery (SFA) after failed antegrade recanalization as an alternative to a conventional transpopliteal approach. A retrospective analysis was undertaken of 50 patients (37 men; mean age 71 years) who underwent retrograde recanalization via a distal SFA access after failed antegrade recanalization of SFA CTOs that were not beyond the adductor canal. Antegrade recanalization failed due to flush SFA occlusion, occluded stents, wire perforation, and re-entry failure. Retrograde SFA access required introduction of a 7- to 15-cm, 21-G needle distal to the occlusion. A 0.018-inch guidewire was inserted through the needle followed by a 4- or 6-F, 10-cm sheath or dedicated support catheter only. All retrograde SFA punctures were performed with the patient in the supine position. Once retrograde passage of the occlusion was successful, oftentimes requiring a "double-balloon" technique to disrupt the dissection membrane with abutting balloons delivered from both access sites, balloon angioplasty and/or stenting could be performed from either direction. Retrograde puncture of the distal SFA was successful in all cases. Retrograde recanalization involved insertion of a 6-F sheath in 3 (6%) cases, a 4-F sheath in 32 (64%), and a sheathless approach in 15 (30%). The "double-balloon" technique was necessary to achieve guidewire passage in 12 cases. Recanalization was successful in 48 (96%) cases. Hemostasis time at the distal puncture site was 9.2 minutes (range 3-30). Perioperative complications included 4 pseudoaneurysms (2 groins, 2 distal), 1 peripheral embolization, and 1 small arteriovenous fistula at the distal puncture site. For failure of antegrade recanalization of SFA occlusions, the retrograde SFA puncture distal to the adductor canal with the patient remaining supine is a safe and successful technique that represents a convenient alternative to the conventional transpopliteal approach.

Dose modulated retrospective ECG-gated versus non-gated 64-row CT angiography of the aorta at the same radiation dose: Comparison of motion artifacts, diagnostic confidence and signal-to-noise-ratios

To compare ECG-gated and non-gated CT angiography of the aorta at the same radiation dose, with regard to motion artifacts (MA), diagnostic confidence (DC) and signal-to-noise-ratios (SNRs). Sixty consecutive patients prospectively randomized into two groups underwent 64-row CT angiography, with or without dose-modulated ECG-gating, of the entire aorta, due to several pathologies of the ascending aorta. MA and DC were both assessed using a four-point scale. SNRs were calculated by dividing the mean enhancement by the standard deviation. The dose-length-product (DLP) of each examination was recorded and the effective dose was estimated. Dose-modulated ECG-gating showed statistically significant advantages over non-gated CT angiography, with regard to MA (p<0.001) and DC (p<0.001), at the aortic valve, at the origin of the coronary arteries, and at the dissection membrane, with a significant correlation (p<0.001) between MA and DC. At the aortic wall, however, ECG-gated CT angiography showed statistically significant fewer MA (p<0.001), but not a statistically significant higher DC (p=0.137) compared to non-gated CT angiography. At the supra-aortic vessels and the descending aorta, the ECG-triggering showed no statistically significant differences with regard to MA (p=0.861 and 0.526, respectively) and DC (p=1.88 and 0.728, respectively). The effective dose of ECG-gated CT angiography (23.24mSv; range, 18.43-25.94mSv) did not differ significantly (p=0.051) from that of non-gated CT angiography (24.28mSv; range, 19.37-29.27mSv). ECG-gated CT angiography of the entire aorta reduces MA and results in a higher DC with the same SNR, compared to non-gated CT angiography at the same radiation dose.

Aortic dissection with sheared-off intimal flap

Fig. 1. Computed tomographic angiography showed dissection of the whole aorta, type Stanford A or DeBakey I, respectively. The free-floating dissection membrane in the ascending aorta is identified by arrowheads. Further details in this image are an ectasia of the ascending aorta (AA), the left coronary artery that was not affected by the dissection (*), hypertrophy of the left ventricular myocardium (LVM) due to known arterial hypertension, and the wire of a transfemoral temporary pacemaker. This pacemaker had been inserted because of a new-onset second-degree atrioventricular block.