Persistent Intraluminal Pressure After Endovascular Stent Grafting for Type B Aortic Dissection.

OBJECTIVES: Despite technically successful thoracic endovascular stent graft repair (TEVAR) in patients with Stanford Type B aortic dissection (TBAD), long-term follow up studies have shown that the false lumen may continue to dilate. The aim of this study was to analyze the possible mechanisms leading to such changes from a hemodynamic perspective. METHODS: Twenty-eight ex vivo fresh porcine TBAD models (Mo A: 10; Model B: 12; Model C: 6) were established to simulate three clinical situations: Model A with patent false lumen (pre-TEVAR); Model B with distal re-entry only (post-TEVAR), and Model C with thrombus filling in the false lumen and a distal re-entry (chronic stage of post-TEVAR). Synchronous pressure waveforms were taken from both the true and the false lumen. True lumen and false lumen pressure differences were calculated for each model as four indices: systolic index (SI), diastolic index (DI), mean pressure index (MPI) and area under curve index (AUCI). These indices were compared between the three models. RESULTS: False lumen pressure and corresponding pressure-accumulating effects were significantly higher in Model A than in Model C: SI (99.9% vs. 189.4%; p < .001); MPI and AUCI (99.5% vs. 128.2%; 99.5% vs. 128%; p < .001). The SI, MPI, and AUCI were significantly higher in Model B compared with Model C. The differences between the four indices were not significant between Model A and B. The false lumen area under curve (AUC) in Model C was merely lowered by 20% compared with its true lumen (67.5 mmHg vs. 85.2 mmHg). CONCLUSION: The false lumen pressure remained unchanged in the non-thrombosed segment with patent blood flow after the primary entry tear sealed. Intraluminal pressure reduction in the thrombosed false lumen was significant. However, nearly 80% of the pressure remained in the thrombosed false lumen. If this high intra-thrombus pressure persists, it may contribute to delayed aneurysmal formation after endovascular treatment.

Custom-made fenestrated stent grafts to preserve accessory renal arteries in patients with abdominal aortic aneurysms.

Accessory renal arteries are common and may contribute significantly to renal perfusion. With the current endovascular design and technology, it is possible to preserve accessory renal arteries during endovascular aneurysm repair (EVAR). We report two patients with custom-made EVAR devices to preserve accessory renal arteries with good mid- and long-term clinical and radiological results. Conventional EVAR would have occluded their origins. As a result of customized fenestrations in commercially available stentgrafts, the patency of large accessory renal arteries can be maintained, whilst securing a proximal seal.

Ex-vivo haemodynamic models for the study of Stanford type B aortic dissection in isolated porcine aorta.

OBJECTIVES: The aim of this study is to present novel ex-vivo models in the study of complex haemodynamical changes in Stanford type B aortic dissection (TBAD). MATERIALS AND METHODS: Fifteen fresh porcine aortas were harvested and preserved with 4 °C saline. Ex-vivo models were developed to simulate TBAD in three different situations: model A with patent false lumen, model B with distal re-entry only and model C with proximal primary entry only. These models were connected to standardised pulsatile pumps and the pressure waveforms were monitored and compared. The aortas were scanned with ultrasonography and subjected to post-experiment autopsy. RESULTS: The three different models were successfully created (n = 13). Pulsatile flow testing was successful and the shapes of the pressure waveforms were similar to those taken from human aorta. Post-testing gross examination confirmed the success of modelling. CONCLUSION: Porcine aortas may prove to be useful ex-vivo models in the study of aortic dissection haemodynamics. These models are reproducible and may be used in the study of complex haemodynamic forces during the development and propagation of TBAD. Our three porcine models give a potential possibility in helping clinicians isolate and analyse complex haemodynamical factors in the development, propagation and prognosis of TBAD.

Delayed presentation of popliteal pseudo-aneurysm following soccer football injury.

Development of pseudo-aneurysm of the popliteal artery usually results from trauma, infection, or iatrogenic causes after orthopedic operations. This is to our knowledge the first reported case in the world's literature of a delayed presentation of a large above-knee popliteal artery pseudo-aneurysm following a soccer football injury. The pseudo-aneurysm severely compressed the native artery, and open exploration with surgical vein-patch repair of the artery was chosen in preference to endovascular stent-graft in view of the compressive symptoms and large size of the chronic pseudo-aneurysm. This case highlights the importance of imaging such as duplex ultrasound, computed tomography, or magnetic resonance angiography if symptoms persist after sports injury.

Spontaneous Retroperitoneal Hematoma Simulating Ruptured Infrarenal Aortic Aneurysm in a Patient with End-Stage Renal Disease.

We reported a case of spontaneous retroperitoneal hematoma (SRH) simulating a ruptured infrarenal aortic aneurysm. A 72-year-old man with a history of infrarenal aortic aneurysm and end-stage renal disease on hemodialysis presented with malaise and nonspecific central abdominal pain and left loin discomfort. An emergency computed tomography scan showed a large retroperitoneal hematoma and clinical suspicion of ruptured infrarenal aortic aneurysm. However, the hematoma was discontinuous with the aneurysm sac and raised the clinical suspicion on dual pathology. The SRH was treated conservatively with transfusion of blood products, and the aneurysm was treated with nonemergency endovascular repair electively. This case demonstrates the importance of recognizing different clinical and radiological characteristics and be aware of dual pathology.

Endovascular infrarenal aneurysm repair in patients with horseshoe kidneys: case series and literature review.

Horseshoe kidney may cause technical and access problems during open aortic aneurysm repair. The aim of this study is to report two cases from our institution and to review the world's literature on successful endovascular infrarenal aneurysm repair in patients with horseshoe kidneys. A retrospective review of a prospectively entered departmental computerized database was performed for the two patients from our institution. Articles were searched electronically from PubMed and Medline, using the terms 'horseshoe kidney' and 'aneurysm'. Endovascular cases were reviewed from the world's literature. In addition to the two patients from our institution, there were 19 patients with infrarenal aneurysms and horseshoe kidneys in published literature who underwent successful endovascular aneurysm repair. The occlusion of lower-pole or accessory renal arteries does not seem to cause significant endoleak or renal impairment in the long run. In conclusion, our experience and current literature seem to suggest that endovascular repair of infrarenal aortic aneurysms for patients with horseshoe kidneys is safe. Renal impairment will depend on the area of kidney perfused by the accessory renal arteries. The endovascular treatment option is less invasive than open repair, and circumvents the problem of difficult exposure, especially in those patients with significant co-morbidity.