Acute Malperfusion Research Articles

Preventing Large Residual False Lumen: Next Step in Evolution of Surgical Treatment of Debakey Type I Dissection

Historically standard emergency open surgical repair of Debakey Type I dissections has focused on resecting the ascending aorta and addressing proximal complications to survive a catastrophic medical condition. The fact that the residual aorta almost always remained dissected was accepted by surgeons because they knew if the residual dissected aortic exhibited aneurysm formation, redo aortic surgery, although complicated, could be done at an elective setting. Over the past decade improved operative mortality rates for emergency repair of Debakey Type I dissections have led innovative surgeons to take interest in extending the extent of aortic repair at the time of the initial operation to address both acute malperfusion and long-term aneurysm formation.

Flow dynamics, false lumens and implications for endografting

The complications of endovascular stenting for type B aortic dissections are well-described and include paralysis from spinal cord ischemia, retrograde dissection, stroke, and access site complications. Owing to the inherent risk associated with this procedure, current practice is to withhold endovascular therapy unless the risk-benefit balance is in favor of intervention, such as with acute malperfusion or aneurysmal degeneration. Emphasis is placed on coverage of the entry tear, which has been advocated theoretically as the primary method to restore normal aortic hemodynamics and induce false lumen thrombosis, despite notable paucity of direct flow modeling to support this claim.

Aortic dissection with acute malperfusion syndrome: Endovascular fenestration via the funnel technique

ObjectiveTo analyze the short- and long-term results of an original aortic fenestration method using the funnel technique during aortic dissection complicated by malperfusion syndrome. MethodsThe funnel technique consists of deployment of an uncovered aortic stent graft placed from the false to the right lumen through an intimal flap aortic fenestration made by balloon angioplasty. Twenty-eight patients presenting with an aortic dissection (type A, n = 19; type B, n = 9) were treated for malperfusion syndrome owing to dynamic compression (16 renal, 17 bowel, and 13 lower limb ischemia) using the aforementioned technique, and had follow-up evaluation at short term (30 days) and long term (mean: 55 ± 40 months). Eight patients had severe ischemia on arrival (6 bowel, 7 renal, 3 lower limb). ResultsTechnical success was achieved in 27 of 28 patients (96%), and ischemic symptoms had disappeared in 25 of 28 patients (89%) at short-term follow up. Five patients presented postprocedure complications: 4 minor and 1 major with arterial thrombosis which caused technical failure (3.6%). The 30-day mortality rate was 7% (n = 2), related to bowel ischemia complications. At long-term follow up, 21 patients had a stable thoracic aortic diameter (91%). ConclusionsThe funnel technique, in cases of malperfusion syndrome after aortic dissection, safely improves short- and long-term clinical outcome, and could represent an interesting alternative in the management of patients. The hemodynamic efficiency of this technique may account for a lower mortality in our series.

Part One: For the Motion. Level 1 Evidence is Necessary Comparing TEVAR and Medical Management of Uncomplicated Type B Aortic Dissection

Part One: For the Motion. Level 1 Evidence is Necessary Comparing TEVAR and Medical Management of Uncomplicated Type B Aortic Dissection

Initial findings and potential applicability of computational simulation of the aorta in acute type B dissection

Type B aortic dissection can be acutely complicated by rapid expansion, rupture, and malperfusion syndromes. Short-term adverse outcomes are associated with failure of the false lumen to thrombose. The reasons behind false lumen patency are poorly understood, and the objective of this pilot study was to use computational fluid dynamics reconstructions of aortic dissection cases to analyze the effect of aortic and primary tear morphology on flow characteristics and clinical outcomes in patients with acute type B dissections. Three-dimensional patient-specific aortic dissection geometry was reconstructed from computed tomography scans of four patients presenting with acute type B aortic dissection and a further patient with sequential follow-up scans. The cases were selected based on their clinical presentation. Two were complicated by acute malperfusion that required emergency intervention. Three patients were uncomplicated and were managed conservatively. The patient-specific aortic models were used in computational simulations to assess the effect of aortic tear morphology on various parameters including flow, velocity, shear stress, and turbulence. Pulsatile flow simulation results showed that flow rate into the false lumen was dependent on both the size and position of the primary tear. Linear regression analysis demonstrated a significant relationship between percentage flow entering the false lumen and the size of the primary entry tear and an inverse relationship between false lumen flow and the site of the entry tear. Subjects complicated by malperfusion had larger-dimension entry tears than the uncomplicated cases (93% and 82% compared with 32% and 55%, respectively). Blood flow, wall shear stress, and turbulence levels varied significantly between subjects depending on aortic geometry. Highest wall shear stress (>7 Pa) was located at the tear edge, and progression of false lumen thrombosis was associated with prolonged particle residence times. Results obtained from this preliminary work suggest that aortic morphology and primary entry tear size and position exert significant effects on flow and other hemodynamic parameters in the dissected aorta in this preliminary work. Blood flow into the false lumen increases with increasing tear size and proximal location. Morphologic analysis coupled with computational fluid dynamic modeling may be useful in predicting acute type B dissection behavior allowing for selection of proper treatment modalities, and further confirmatory studies are warranted.

Thoracic Endovascular Aortic Repair for Retrograde Type A Aortic Dissection with an Entry Tear in the Descending Aorta

PurposeTo report the immediate and follow-up outcome of thoracic endovascular aortic repair (TEVAR) in highly selected patients with retrograde type A aortic dissection (RAAD) and an entry tear in the descending aorta. Materials and MethodsTEVAR was performed in 17 patients with RAAD and an entry tear in the descending aorta. None of the patients had severe aortic regurgitation, cardiac tamponade, coronary artery involvement, or brain ischemia. The false lumen in the ascending aorta was patent in nine patients. Two patients had acute malperfusion of the branched artery. Computed tomography (CT) was performed 14 days, 3 months, and 6 months after the intervention and annually thereafter. ResultsAll procedures were technically successful, with complete coverage of the entry tear and complete thrombosis of the false lumen in the ascending aorta. All patients survived through the follow-up period (25.7 months ± 17.2). TEVAR resulted in thrombosis of the false lumen, reabsorption of the false lumen thrombus, and enlargement of the true lumen. The mean maximal diameter of the ascending aorta and the false lumen in the ascending aorta significantly decreased after TEVAR. At the distal edge of the stent graft, the mean diameter of the descending aorta and the false lumen markedly decreased after TEVAR. Complete thrombosis of the false lumen was observed at the distal edge of the stent graft in 16 (94.1%) patients and at the diaphragmatic level in 9 (52.9%) patients. ConclusionsTEVAR for RAAD with an entry tear in the descending aorta is a safe and effective technique in highly selected patients.

Placement of Endovascular Stent Graft in Acute Malperfusion Syndrome After Acute Type II Aortic Dissection

Acute malperfusion syndrome is a serious complication of acute aortic dissection. A 76-year-old female patient was admitted with acute type B aortic dissection and developed renal malperfusion during medical therapy. We are reporting a clinically successful result from the thoracic endovascular aortic repair used for malperfusion syndrome that occurred by acute type B aortic dissection.

Endovascular fenestration in aortic dissection with acute malperfusion syndrome: Immediate and late follow-up

To evaluate the immediate and long-term results of fenestration in aortic dissection with acute malperfusion syndrome. Between 1999 and 2007, 35 patients (31 men; age, 57 ± 11 years) with aortic dissection (19 with type A and 16 with type B) were treated by fenestration for malperfusion syndrome (27 renal, 27 bowel, and 14 lower limb) due to dynamic compression. Fenestration was performed with 2 rigid guidewires inserted in one 8F sheath (45 cm long). The mean interval between aortic dissection and fenestration was 5 days (28 patients within 3 days and 7 patients between 9 and 41 days). Fenestration (100% technical success rate) with an additional endovascular procedure (29 peripheral stents and 1 thoracic stent graft) resulted in angiographic success in 97% of the patients. Bowel surgery was performed in 7 patients. Mortality within the first month (12/35) was related to bowel ischemia (n = 5), neurologic complications (n = 3), type A surgery (n = 2), and late treatment (n = 2). At a mean follow-up of 48 ± 30 months, 4 of the remaining 23 patients had died and 2 had withdrawn from the study. The diameter of the aorta, as measured using computed tomography/magnetic resonance imaging, remained stable in 12 of the remaining 17 patients and had increased in 5 (1 with Marfan syndrome and 4 with multiple arterial ectasia). In emergencies, fenestration saved 69% of the patients with acute malperfusion syndrome in complicated aortic dissection. During the follow-up period, the aortic diameter remained stable in most of the surviving patients.

Endovascular Treatment of Acute Complicated Aortic Dissection: Long-term Follow-up of Clinical Outcomes and CT Findings

To investigate changes of the aorta and affected end organs after endovascular treatment of an acute complicated aortic dissection. Twenty patients who underwent endovascular treatment for acute complicated aortic dissection were evaluated for computed tomographic (CT) findings of the aorta and affected end organs. Three patients had Stanford type A dissection and 17 patients had Stanford type B dissection. The follow-up period ranged from 3 to 2,719 days (mean, 731 d). The outer diameter of the aorta and the inner diameter of the true and false lumen were compared between initial and follow-up CT. Renal perfusion, size, and changes of other affected organs were evaluated on initial and follow-up CT studies. Branch vessel malperfusion improved in 18 of 20 patients (90%). The outer diameter of the aorta was increased at all levels (thoracic aorta, 10.9%; abdominal aorta, 11.8%; infrarenal aorta, 12.6%). The greatest expansion of aortic false lumen was seen in the thoracic aorta (19%). Annual growth rates were 3.64 mm per year in the thoracic aorta, 2.64 mm per year at the celiac level of the abdominal aorta, and 1.42 mm per year in the infrarenal aorta. Affected kidneys showed atrophy in 67% of cases in the right kidney and 83% of cases in the left kidney. Limb malperfusion improved in 78% of patients, but gallbladder ischemia improved in only 33%. Although fenestration and endovascular stent placement is effective for improving acute malperfusion syndrome in type B aortic dissection, it cannot prevent delayed expansion of the aorta.