Sung W. Ham

Arch and visceral/renal debranching combined with endovascular repair for thoracic and thoracoabdominal aortic aneurysms

OBJECTIVE We report a single-center experience using the hybrid procedure, consisting of open debranching, followed by endovascular aortic repair, for treatment of arch/proximal descending thoracic/thoracoabdominal aortic aneurysms (TAAA). METHODS From 2005 to 2010, 51 patients (33 men; mean age, 70 years) underwent a hybrid procedure for arch/proximal descending thoracic/TAAA. The 30-day and in-hospital morbidity and mortality rates, and late endoleak, graft patency, and survival were analyzed. Graft patency was assessed by computed tomography, angiography, or duplex ultrasound imaging. RESULTS Hybrid procedures were used to treat 27 thoracic (16 arch, 11 proximal descending thoracic) and 24 TAAA (Crawford/Safi types I to III: 3; type IV: 12; type V: 9). The hybrid procedure involved debranching 47 arch vessels or 77 visceral/renal vessels using bypass grafts, followed by endovascular repair. Seventy-five percent of debranching and endovascular repair procedures were staged, with an average interval of 28 days. Major 30-day and in-hospital complications occurred in 39% of patients and included bypass graft occlusion in four, endoleak reintervention in two, and paraplegia in one. Mortality was 3.9%. During a mean follow-up of 13 months, three additional type II endoleaks required intervention, and one bypass graft occluded. No aneurysm rupture occurred during follow-up. Primary bypass graft patency was 95.3%. Actuarial survival was 86% at 1 year and 67% at 3 years. CONCLUSION The hybrid procedure is associated with acceptable rates of mortality and paraplegia when used for treatment of arch/proximal descending thoracic/TAAA. These results support this procedure as a reasonable approach to a difficult surgical problem; however, longer follow-up is required to appraise its ultimate clinical utility.

Aortic Morphologic Findings After Thoracic Endovascular Aortic Repair for Type B Aortic Dissection

IMPORTANCE Thoracic endovascular aortic repair (TEVAR) is used in the treatment of type B aortic dissections. Information related to aortic morphologic findings and the condition of the abdominal aorta after TEVAR is limited. OBJECTIVE To analyze aortic morphologic findings after TEVAR for type B aortic dissections. DESIGN, SETTING, AND PARTICIPANTS After a retrospective database review, the data for 30 patients who underwent TEVAR from January 1, 2007, through December 31, 2013, for type B aortic dissection were analyzed. Imaging software was used to calculate aortic diameters and volumes of the aorta on computed tomography (CT) or magnetic resonance imaging (MRI). Mean follow-up was 14.4 months. INTERVENTIONS We performed TEVAR to cover proximal thoracic aorta tears in patients who underwent acute or chronic type B aortic dissections. MAIN OUTCOMES AND MEASURES Aortic morphologic findings of pre-TEVAR CT or MRI were compared with the most recent findings of post-TEVAR CT or MRI. Frequency of thoracic false lumen thrombosis (FLT) and false lumen patency (FLP) was determined and the effect on post-TEVAR aortic morphologic findings analyzed. RESULTS Mean (SD) TEVAR increased true lumen diameter (19.50 [6.92] mm to 31.19 [5.36] mm, P < .001) and volume (77.92 [41.70] mL to 166.95 [69.69] mL, P < .001) and decreased false lumen diameter (29.77 [12.55] mm to 21.92 [12.05] mm, P = .001) on post-TEVAR CT or MRI when compared with pre-TEVAR scans. Seventy percent of patients experienced thoracic FLT; 30% had FLP. True lumen volume expansion and false lumen volume regression occurred in patients with FLT (82.07 [46.95] mm to 180.55 [77.99] mm, P < .001 and 161.84 [106.36] mm to 115.76 [140.77] mm, P = .002, respectively) and FLP (68.23 [21.43] mm to 128.22 [21.46] mm, P < .001 and 238.64 [174.00] mm to 198.93 [120.46] mm, P = .04, respectively). Patients with FLT had increased true lumen diameter (15.67 [6.43] mm to 26.13 [7.62] mm, P < .001) and volume (54.86 [30.52] mL to 88.08 [41.07] mL, P = .001) in the abdominal aorta after TEVAR, with no change in total abdominal aortic volume (161.94 [70.12] mL vs 160.36 [82.11] mL, P = .90). Total abdominal aortic volume significantly increased in patients with thoracic FLP (187.24 [89.88] mL to 221.41 [82.64] mL, P = .02). CONCLUSIONS AND RELEVANCE Favorable aortic remodeling of the thoracic aorta occurs after TEVAR for type B aortic dissections in patients with thoracic FLT and FLP. However, failure to achieve thrombosis of the thoracic false lumen negatively influences aortic morphologic findings of the contiguous abdominal aorta.

Disease progression after initial surgical intervention for Takayasu arteritis

OBJECTIVE This study was conducted to determine the incidence of disease progression and the need for subsequent revascularization procedures in patients with Takayasu arteritis (TA). METHODS From 1980 to 2009, all patients with TA who underwent an initial revascularization procedure for end-organ ischemia were identified. The incidence of subsequent revascularization in another vascular bed or revision of the initial procedure was determined. RESULTS Forty patients (36 women; mean age, 35) underwent an initial revascularization procedure. Indications for the initial procedure were hypertension in 20, renal dysfunction in 9, extremity ischemia in 6, and stroke/transient ischemic attack in 5. The initial revascularization consisted of 60 bypass procedures and 4 endovascular interventions. During a mean follow-up of 6.4 years, progression of TA in another vascular bed or stenosis/occlusion of the initial revascularization procedure occurred in 16 patients (40%). Five patients with progression required one procedure, whereas 11 required two or more surgical interventions. Procedures required were renal in 12, cerebrovascular in 8, extremity in 8, aortic reconstruction in 5, and mesenteric in 1. Postoperative/30-day morbidity was 14%, and one operative death occurred. Actuarial survival was 94% at 1 year and 85% at 5 years after the remedial procedure. CONCLUSIONS TA progression is common in patients who require revascularization for end-organ ischemia. This finding emphasizes the need for global lifelong vascular surveillance of all patients who undergo surgical intervention for TA. The effect of steroid and immunosuppressive therapy on reducing reoperation requires further study.

Outcomes after abdominal aortic aneurysm repair requiring a suprarenal cross-clamp

OBJECTIVE The objective of this study was to analyze the early and late outcomes of patients who require a suprarenal aortic cross-clamp during elective open repair of an abdominal aortic aneurysm (AAA). METHODS Patients from 1998 to 2012 who required a suprarenal aortic cross-clamp during elective open AAA repair were reviewed. Data abstracted included demographics and comorbidities; preoperative, perioperative, and late renal function; late interventions related to AAA repair; and late mortality. A decrease in renal function was defined as a >30% decline in estimated glomerular filtration rate (eGFR) compared with the preoperative value. Primary outcomes included renal function, intervention-free survival, and overall survival. RESULTS During the study period, 211 patients underwent open elective or urgent AAA repair; 69 required a suprarenal cross-clamp. The mean age was 71 years, and 80% were men. The mean preoperative creatinine concentration was 1.2 mg/dL, and the mean preoperative eGFR was 66 mL/min/1.73 m2. Location of the aortic cross-clamp was suprarenal (37), supramesenteric (21), and supraceliac (11). Perioperatively, 21 patients (30%) experienced a significant decrease in eGFR; four patients required hemodialysis. Six patients had full recovery of renal function by discharge. Perioperative morbidity and mortality were 35% and 4%, respectively. At a mean follow-up of 3 years, seven patients had an eGFR significantly less than the preoperative value. Late interventions related to the AAA repair were required in eight patients. Indications included wound complication (3), anastomotic aneurysm (2), incisional hernia (1), anastomotic graft stenosis (1), and proximal aortic dilation (1). Overall 5-year intervention-free survival was 62% and overall survival 77%. Intervention-free survival was enhanced by antiplatelet use (P = .04), whereas overall survival was decreased by chronic obstructive pulmonary disease (P = .003) and perioperative pneumonia (P = .001). CONCLUSIONS More than a quarter of patients requiring a suprarenal cross-clamp during open AAA repair experience renal dysfunction. Late graft-related complications are few, with preoperative and perioperative pulmonary function negatively affecting overall patient survival.

Thrombin use in surgery: an evidence-based review of its clinical use

When surgical ligation of bleeding fails, or is not possible, surgeons rely on a number of hemostatic aids, including thrombin. This review discusses the history, pharmacology and clinical application of thrombin as a surgical hemostat. The initial thrombin was bovine in origin, but its use has been complicated by the formation of antibodies that cross-react with human coagulation factors. This has been associated with life-threatening bleeding and in some circumstances anaphylaxis and death. Human thrombin, isolated from pooled plasma of donors, was developed in an effort to minimize these risks, but its downsides are its limited availability and the potential for transmitting blood-borne pathogens. Recently a recombinant thrombin has been developed, and approved for use by the FDA. It has the advantage of being minimally antigenic and devoid of the risk of viral transmission. Thrombin is often used in conjunction with other hemostatic aids, including absorbable agents such as Gelfoam, and with fibrinogen in fibrin glues. The last part of this review will discuss these agents in detail, and review their clinical applications.

Development of a Flexible Implantable Sensor for Postoperative Monitoring of Blood Flow

We have developed a blood flow measurement system using Doppler ultrasound flow sensors fabricated of thin and flexible piezoelectric‐polymer films. These flow sensors can be wrapped around a blood vessel and accurately measure flow. The innovation that makes this flow sensor possible is the diffraction‐grating transducer. A conventional transducer produces a sound beam perpendicular to its face; therefore, when placed on the wall of a blood vessel, the Doppler shift in the backscattered ultrasound from blood theoretically would be 0. The diffraction‐grating transducer produces a beam at a known angle to its face; therefore, backscattered ultrasound from the vessel will contain a Doppler signal. Flow sensors were fabricated by spin coating a poly(vinylidene fluoride–trifluoroethylene) copolymer film onto a flexible substrate with patterned gold electrodes. Custom‐designed battery‐operated continuous wave Doppler electronics along with a laptop computer completed the system. A prototype flow sensor was evaluated experimentally by measuring blood flow in a flow phantom and the infrarenal aorta of an adult New Zealand White rabbit. The flow phantom experiment demonstrated that the error in average velocity and volume blood flow was less than 6% for 30 measurements taken over a 2.5‐hour period. The peak blood velocity through the rabbit infrarenal aorta measured by the flow sensor was 118 cm/s, within 1.7% of the measurement obtained using a duplex ultrasound system. The flow sensor and electronics operated continuously during the course of the 5‐hour experiment after the incision on the animal was closed.

Thoracic aortic stent-grafting for acute, complicated, type B aortic dissections.

BACKGROUND To report a single-center experience of aortic stent-grafting for the treatment of acute, complicated, type B aortic dissections. METHODS A retrospective review was conducted of the data obtained from all patients who underwent endovascular stent-grafting for acute, type B aortic dissection between 2006 and 2009. The primary and secondary endpoints were 30-day mortality and morbidity rates, respectively. RESULTS In all, 104 thoracic endovascular aortic aneurysm repairs were performed during the study period. Nine (8.6%) patients (six men; mean age: 65 years) underwent thoracic endovascular aortic aneurysm repair for acute, complicated, type B aortic dissections. Seven (78%) patients had uncontrolled hypertension on presentation. Visceral branch vessel involvement of the dissection was limited to the celiac axis origin in one patient with no evidence of visceral malperfusion. The indication for repair was aortic rupture in five patients, renal malperfusion in two, and persistent pain in the remaining two. Average time taken from presentation to surgery was 5.5 days. Two patients presenting with aortic ruptures had retrograde extension of the dissection that required replacement of the aortic valve and ascending aorta. The mean length of thoracic aorta covered was 21 cm. Complete coverage of the left subclavian artery was required in three patients and partial coverage in two. On completion angiogram, two type I endoleaks were detected, one of which was resolved by postoperative day 5. The 30-day mortality rate was 22%. One mortality was secondary to aortic rupture. The other mortality was due to multiorgan system failure. Seven patients (78%) had one or more major complications. There were no strokes or paraplegia. CONCLUSION The association of morbidity and mortality with endovascular stent-grafting for acute, complicated, type B aortic dissections is significant, which most likely reflects the lethal nature of the disease. The precise role of endovascular treatment in these patients remains to be defined.

Type B Aortic Dissections: Current Guidelines for Treatment

Stanford type B aortic dissections (TBADs) involve the descending aorta and can present with complications, including malperfusion syndrome or aortic rupture, which are associated with significant morbidity and mortality if left untreated. Clinical diagnosis is straightforward, typically confirmed using CT angiography. Treatment begins with immediate anti-impulse medical therapy. Acute TBAD with complications should be repaired with emergent thoracic endovascular aortic repair (TEVAR). Uncomplicated TBAD with high-risk features should undergo TEVAR in the subacute phase. Open surgical repair is seldom required and reserved only for select cases. It is critical to follow these patients clinically and radiographically in the outpatient setting.

Predictors and Consequences of Hemodynamic Instability after Carotid Artery Stenting

BACKGROUND The purpose of this study was to determine the predictors and consequences of hemodynamic instability (HI) after carotid artery stenting (CAS). METHODS The records of all patients undergoing CAS in a single institution were reviewed. Patient demographics and risk factors were recorded. Indications for CAS, medications including statins, atropine, and beta blockers, anatomic risk factors, balloon and stent length and diameter, and degree of stenosis were noted. The presence of periprocedural hypertension (systolic blood pressure [SBP] >160), hypotension (SBP <90), and bradycardia (heart rate <60) lasting longer than 1 hr was documented, as was more transient HI. Rates of transient ischemic attack (TIA), stroke, myocardial infarction (MI), and death within 30 days of the procedure were calculated. Chi-squared analysis was used to determine the role of periprocedural factors in predicting the risk of HI and to determine if patients experiencing HI were more likely to experience major adverse events (MAEs) than those who did not. RESULTS Between 2005 and 2012, 199 CAS were performed in 191 patients. One hundred seventeen were men and 74 were women. Their ages ranged from 46 to 92 years (mean, 73.6 years). Eighty-seven percent had hypertension, 48.5% were smokers, 48% had coronary disease, and 38% were diabetic. CAS was performed for asymptomatic stenosis in 55% of patients, 24% had previous TIA, and 20% previous stroke. Sixty-three percent of patients were on statins, 41.4% on beta blockers, and 92% received atropine before balloon dilatation or stent placement. Overall, 130 (65.3%) patients experienced HI and 67 patients (33.7%) experienced HI lasting longer than 1 hr. Octogenarians were more likely to experience both transient and prolonged HI, whereas angina or contralateral occlusion was predictive of any HI, and female sex was predictive of prolonged HI. Transient HI was not predictive of MAE. Patients with HI persisting longer than 1 hr were more likely to experience a TIA than those who did not (P = 0.045), but they were no more likely to experience stroke, MI, or death (P > 0.35 for each). CONCLUSIONS Periprocedural HI occurs frequently during CAS even with prophylactic atropine administration. Although patients experiencing HI were more likely to experience a TIA, its presence is not associated with an increase in stroke, MI, or death.

Symptomatic Intragraft Thrombus following Endovascular Repair of Blunt Thoracic Aortic Injury

Thoracic endovascular aortic repair (TEVAR) can be complicated by graft collapse, endoleaks, and stent migration. The incidence of these complications and other outcomes is poorly understood in young trauma victims who receive endovascular aortic repair of blunt thoracic aortic injury (BTAI). A 29-year-old pedestrian was struck by a vehicle resulting in polytrauma including BTAI with transection distal to the left subclavian artery origin. The patient underwent successful TEVAR. Nine months later, the patient developed transient paresthesia below the waist that progressed to bilateral lower extremity paralysis and malperfusion syndrome below the diaphragm including nonpalpable pulses in the lower extremities, acute renal failure, and ischemic colitis. Imaging demonstrated near occlusive thrombosis of the distal end of the thoracic endograft. An emergent axillobifemoral bypass resolved the organ malperfusion and acute limb ischemia. Patients who have undergone TEVAR for BTAI may develop asymptomatic or symptomatic intragraft thrombosis. In patients presenting with malperfusion syndrome below the diaphragm, extra-anatomic bypass can expeditiously resolve symptoms until definitive treatment can be performed. Oversizing of thoracic stents in trauma patient may lead to intragraft thrombosis.