Joost A. van Herwaarden

Vertical Displacement of the Beating Heart by the Octopus Tissue Stabilizer: Influence on Coronary Flow

BACKGROUND In beating heart coronary artery bypass graft operations, biventricular pump failure, as observed after exposure of the posterior circumflex branches by sternotomy, may originate from mechanical obstruction to coronary flow. METHODS Regional coronary blood flow was measured in 8 anesthetized, paced, beta-blocked pigs, and the beating heart was fully retracted. RESULTS Displacement decreased cardiac output from 4.8 +/- 1.1 L/min (mean +/- standard deviation) to 2.8 +/- 1.2 L/min (p < 0.001), a 42% +/- 6% decrease that resulted in a decrease in mean arterial pressure by 48% +/- 6% (mean +/- standard error of the mean; p < 0.001) and a reduction in coronary blood flow in the left anterior descending coronary artery, the right coronary artery, and the circumflex coronary artery by 34% +/- 6%, 25% +/- 8%, and 50% +/- 10%, respectively (all p < 0.05 versus baseline). Relative circumflex coronary artery flow was 20.1% +/- 8.3% lower than the combined relative value of left anterior descending coronary artery and right coronary artery flows (p = 0.046). Subsequent 20 degrees head-down tilt significantly increased ventricular preload pressures and restored cardiac output and mean arterial pressure as well as coronary blood flow. CONCLUSIONS It is inferred that coronary blood flow was not mechanically obstructed during anterior displacement of the porcine beating heart, because augmentation of preloads by the maneuver of Trendelenburg restored coronary flow parallel to the recovery of cardiac output and mean arterial pressure while the heart remained retracted by 90 degrees.

Importance of false lumen thrombosis in type B aortic dissection prognosis

BACKGROUND Partial thrombosis of the false lumen has been reported as a significant predictor of mortality during follow-up in patients with acute type B aortic dissection. The purpose of this study was to investigate the correlation of false lumen thrombosis and aortic expansion during follow-up in patients with acute type B aortic dissection. METHODS All medically treated patients with acute type B aortic dissection observed in 4 cardiovascular referral centers between 1998 and 2011, with admission and follow-up computed tomography or magnetic resonance imaging scans, were included. Aortic diameters of the dissected aortas were measured at 4 levels on the baseline and follow-up scans, and annual growth rates were calculated. Univariate and multivariate regression analyses were used to investigate the effect of false lumen thrombosis on aortic growth rate. RESULTS A total of 84 patients were included, of whom 40 (47.6%) had a partially thrombosed false lumen, 7 (8.3%) had a completely thrombosed false lumen, and 37 (44.0%) had a patent false lumen. A total of 273 of the 336 (81.3%) evaluated aortic levels were dissected segments. Overall, the mean aortic diameter increased significantly at all evaluated levels (P < .001). Univariate analysis showed that annual aortic growth rates were significantly higher in those segments having a false lumen with partial thrombosis (mean, 4.25 ± 10.2) when compared with the patent group (mean, 2.10 ± 5.56; P = .035). In multivariate analysis, partial lumen thrombosis was an independent predictor of higher aortic growth (adjusted mean difference, 2.05 mm/year; 95% confidence interval, 0.10-4.01; P = .040). CONCLUSIONS In patients with acute type B aortic dissection, aortic segments with a partially thrombosed false lumen have a significantly higher annual aortic growth rate when compared with those presenting with patent or complete thrombosis of the false lumen. Therefore, patients with partial thrombosis require more intensive follow-up and may benefit from prophylactic intervention.

Use of dynamic computed tomography to evaluate pre- and postoperative aortic changes in AAA patients undergoing endovascular aneurysm repair

Purpose: To utilize dynamic computed tomographic angiography (CTA) on pre- and postoperative endovascular aneurysm repair (EVAR) patients to characterize cardiac-induced aortic motion within the aneurysm neck, an essential EVAR sealing zone. Methods: Electrocardiographically-gated CTA datasets were acquired utilizing a 64-slice Philips Brilliance CT scanner on 15 consecutive pre- and postoperative AAA patients. Axial pulsatility measurements were taken at 2 clinically relevant levels within the aneurysm neck: 2 cm above the highest renal artery and 1 cm below the lowest renal artery. Changes in aortic area and diameter were determined. Results: Significant aortic pulsatility exists within the aneurysm neck during the cardiac cycle. Preoperative aortic area increased significantly, with a maximum increase of up to 12.5%. The presence of an endograft did not affect aortic pulsatility (p = NS). Postoperative area also changed significantly during a heart cycle, with a maximum increase of up to 14.5%. Diameter measurements demonstrated an identical pattern, with significant pre- and postoperative intracardiac pulsatility within and above the aneurysm neck (p<0.05). An increase in maximum diameter change up to 15% was evident. Conclusion: Patients undergoing EVAR experience aortic diameter changes within and above the aneurysm neck. The presence of an endograft does not abrogate this response to intracardiac pressure changes. Static CT imaging may not adequately identify patients with large aortic pulsatility, potentially resulting in endograft undersizing, stent-graft migration, intermittent type I endoleaks, and poor patient outcomes. The current standard regime of 10% to 15% oversizing based on static CT may be inadequate for some patients.

Predictors of aortic growth in uncomplicated type B aortic dissection

BACKGROUND Patients with uncomplicated acute type B aortic dissection (ABAD) generally can be treated with conservative medical management. However, these patients may develop aortic enlargement during follow-up, with the risk for rupture, which necessitates intervention. Several predictors have been studied in recent years to identify ABAD patients at high risk for aortic enlargement who may benefit from early surgical or endovascular intervention. This study systematically reviewed and summarized the current available literature on prognostic variables related to aortic enlargement during follow-up in uncomplicated ABAD patients. METHODS Studies were included if they reported predictors of aortic growth in uncomplicated ABAD patients. Studies about type A aortic dissection, aortic aneurysm, intramural hematoma, or ABAD that required acute intervention were excluded. RESULTS A total of 18 full-text articles were selected. The following predictors of aortic growth in ABAD patients were identified: age <60 years, white race, Marfan syndrome, high fibrinogen-fibrin degradation product level (≥20 μg/mL) at admission, aortic diameter ≥40 mm on initial imaging, proximal descending thoracic aorta false lumen (FL) diameter ≥22 mm, elliptic formation of the true lumen, patent FL, partially thrombosed FL, saccular formation of the FL, presence of one entry tear, large entry tear (≥10 mm) located in the proximal part of the dissection, FL located at the inner aortic curvature, fusiform dilated proximal descending aorta, and areas with ulcer-like projections. Tight heart rate control (<60 beats/min), use of calcium-channel blockers, thrombosed FL, two or more entry tears, FL located at the outer aortic curvature, and circular configuration of the true lumen were associated with negative or limited aortic growth. CONCLUSIONS Several predictors might be used to identify those ABAD patients at high risk for aortic growth. Although conservative management remains indicated in uncomplicated ABAD, these patients might benefit from closer follow-up or early endovascular intervention.

One-year multicenter results of 100 abdominal aortic aneurysm patients treated with the Endurant stent graft

OBJECTIVE The Endurant (Medtronic, Minneapolis, Minn) is a new stent graft specifically designed to make more patients anatomically eligible for endovascular aneurysm (EVAR). This study presents the 1-year results of 100 consecutive patients with abdominal aortic aneurysms (AAAs) treated with the Endurant stent graft in real-life practice. METHODS All clinical preoperative, operative, postoperative, and 1-year follow-up data of patients with the Endurant stent graft from three tertiary centers were prospectively collected. Patients underwent computed tomographic angiography (CTA) preoperatively, at 1 month, and at 1-year post-EVAR. The first 100 patients with an implantation date at least 1 year before our date of analysis and complete information were included. Clinical data, AAA characteristics, presence of endoleaks, graft migration, and other EVAR-related complications were noted. All values are stated as mean ± SD (range). RESULTS This study included 100 patients with AAAs (88 men) with a mean age of 73 ± 8 years (47 to 87 years), an AAA size of 61 ± 10 mm (31 to 93 mm), an AAA volume of 210 ± 122 mL (69 to 934 mL), a proximal neck length of 33 ± 14 mm (9 to 82 mm), and an infrarenal angulation of 44 ± 25° (0°-108°). Nineteen of the 100 included patients had at least one anatomic characteristic that was considered a violation of the instructions for use (IFU) of the Endurant stent graft. A primary technical success was achieved in 98% of the patients (one additional stent placement in renal artery was required; one unplanned aorto-uni-iliac device placed), with no primary type I or III endoleaks or conversions. A secondary technical success was achieved in all cases. The 30-day mortality was 2% and the first postoperative CTA documented 16 endoleaks (16%; 16 type II). One-year follow-up showed three iliac limb occlusions (3%), one infected stent graft (causing a type Ia endoleak), and five endovascular reinterventions (5%; three to treat iliac limb occlusions, one proximal extension cuff; and one stent in the renal artery). The 1-year all-cause mortality rate was 12% (12 patients) and the AAA-related mortality was 3%. The mean AAA size was significantly smaller after 1 year (diameter, 54 ± 11.8 [32-80] mm; P < .01; volume, 173 ± 119 [42-1028] mL; P < .01), and one graft migration >5 mm and 13 endoleaks were noted (12 type II, 1 type I [neck dilatation]). CONCLUSION The treatment of patients with AAAs with the Endurant stent graft seems to be successful and durable during the first year after EVAR. Despite the wider inclusion criteria for the Endurant, and with 19% of our patients treated outside the IFU, the AAA-related mortality, number of type I or III endoleaks, and reintervention rates are comparable to the results of other stent grafts.

Intraluminal abdominal aortic aneurysm thrombus is associated with disruption of wall integrity

OBJECTIVE An association of intraluminal thrombus (ILT) with abdominal aortic aneurysm (AAA) growth has been suggested. Previous in vitro experiments have demonstrated that aneurysm-associated thrombus may secrete proteolytic enzymes and may develop local hypoxia that might lead to the formation of tissue-damaging reactive oxygen species. In this study, we assessed the hypothesis that ventral ILT thickness is associated with markers of proteolysis and with lipid oxidation in the underlying AAA vessel wall. METHODS Ventral AAA tissue was collected from asymptomatic patients at the site of maximal diameter during open aneurysm repair. Segments were divided, one part for biochemical measurements and one for histologic analyses. We measured total cathepsin B, cathepsin S levels, and matrix metalloproteinase (MMP)-2 and MMP-9 activity. Myeloperoxidase and thiobarbituric acid reactive substances were determined as measures of lipid oxidation. Histologic segments were analyzed semiquantitatively for the presence of collagen, elastin, vascular smooth muscle cells (VSMCs), and inflammatory cells. Preoperative computed tomography angiography scans of 83 consecutive patients were analyzed. A three-dimensional reconstruction was obtained, and a center lumen line of the aorta was constructed. Ventral ILT thickness was measured in the anteroposterior direction at the level of maximal aneurysm diameter on the orthogonal slices. RESULTS Ventral ILT thickness was positively correlated with aortic diameter (r=0.25; P=.02) and with MMP-2 levels (r=0.27; P=.02). No biochemical correlations were observed with MMP-9 activity or cathepsin B and S expression. No correlation between ventral ILT thickness and myeloperoxidase or thiobarbituric acid reactive substances was observed. Ventral ILT thickness was negatively correlated with VSMCs (no staining, 18.5 [interquartile range, 12.0-25.5] mm; minor, 17.6 [10.7-22.1] mm; moderate, 14.5 [4.6-21.7] mm; and heavy, 8.0 [0.0-12.3] mm, respectively; P=.01) and the amount of elastin (no staining, 18.6 [12.2-30.0] mm; minor, 16.5 [9.0-22.1] mm; moderate, 11.7 [2.5-15.3] mm; and heavy 7.7 [0.0-7.7] mm, respectively; P=.01) in the medial aortic layer. CONCLUSIONS ILT thickness appeared to be associated with VSMCs apoptosis and elastin degradation and was positively associated with MMP-2 concentrations in the underlying wall. This suggests that ILT thickness affects AAA wall stability and might contribute to AAA growth and rupture. ILT thickness was not correlated with markers of lipid oxidation.

Validation of a new standardized method to measure proximal aneurysm neck angulation

PURPOSE This study presented and validated a new standardized method for the measurement of the aortic angulation in patients with abdominal aortic aneurysms (AAA) and quantified the observer variability. METHODS A standardized method to quantify aortic angulation was introduced. To measure aortic angulation, a center lumen line (CLL) of the aorta was made, and a three-dimensional (3D) aortic reconstruction was obtained. The 3D reconstruction was turned 360 degrees perpendicular to the CLL in the middle of the flexure. The sharpest angle of the CLL was considered the true angle of the aortic axis. The computed tomography angiography data sets of 20 patients scheduled for endovascular aneurysm repair (EVAR) were obtained. The angles between the suprarenal aorta and the aneurysm neck (alpha) and between the aneurysm neck and sac (beta) were measured. Two observers independently measured the angles. Differences of each pair of measurements were plotted against their mean and intraobserver and interobserver variabilities were calculated according to Bland and Altman. RESULTS The intraobserver mean difference for angle alpha was -0.2 degrees (-0.5%), with a repeatability coefficient (RC) of 6.4 degrees (20.2%), and 0.6 degrees (1.4%) for angle beta, with a RC of 6.2 degrees (13.4%). The interobserver mean difference for angle alpha was -1.5 degrees (-4.5%), with a RC of 6.9 degrees (22.0%), and -0.2 degrees (-0.4%) for angle beta, with a RC of 7.4 degrees (16.0%). No significant differences were observed between the observers. CONCLUSION The presented technique to objectively quantify the angulation of the aneurysm neck is easy to perform and reliable. This method showed good intraobserver and interobserver variability and should therefore be the standard when measuring and reporting aortic angulation.

Morphologic predictors of aortic dilatation in type B aortic dissection

BACKGROUND Conservative management of acute type B aortic dissection (ABAD) is often associated with aortic dilatation during follow-up increasing the risk of aortic rupture. The goal of this study was to investigate whether morphologic characteristics of the dissection can predict aortic growth. METHODS All conservatively managed ABAD patients from four referral centers were included (2000 to 2010). Aortic diameters were measured at five levels at baseline and at the last follow-up computed tomography angiography, and annual aortic growth rates were calculated for all segments. Linear regression was used to study the influence of aortic morphologic characteristics for aortic dilatation. RESULTS Included were 62 patients (41 men) with a mean age of 60.3 ± 10.7 years. Among the 310 analyzed aortic segments, 248 (80.0%) were dissected, of which 211 (85.1%) showed aortic growth. Overall, the mean diameter increased from 36.1 ± 9.4 to 40.2 ± 11.1 mm (P < .01), which corresponds with a mean aortic growth rate of 3.1 ± 6.3 mm/y. Multivariate linear regression analysis showed that male sex (95% confidence interval [CI], 0.60-4.04; P = .005) and a saccular false lumen (95% CI, 2.07-7.81: P = .001) were associated with a significantly increased aortic growth rate. Increasing age (95% CI, -0.23 to -0.04; P = .005), increased number of entry tears (95% CI, -2.40 to -0.43; P = .005), false lumen located on the aortic outer curvature (95% CI, -4.30 to -0.38; P = .019), and a circular configuration of the true lumen (95% CI, -5.35 to -0.32; P = .027) were associated with a decreased aortic growth rate. CONCLUSIONS Multiple morphologic characteristics appear to predict aortic dilatation in ABAD patients treated medically. Early assessment of these morphologic signs may be useful in the selection of ABAD patients who might benefit from closer radiologic surveillance or prophylactic intervention.

TEVAR following prior abdominal aortic aneurysm surgery: Increased risk of neurological deficit

OBJECTIVE Evidence regarding the impact of prior abdominal aortic aneurysm (AAA) repair on the risk of neurological deficit after thoracic endovascular aortic aneurysm repair (TEVAR) is lacking. The purpose of this study was to characterize the risk of TEVAR-related neurological deficit in patients who previously underwent infrarenal AAA surgery. METHODS Prospective maintained databases of patients undergoing TEVAR in the participating institutions were searched for patients with a history of prior AAA surgery before TEVAR. Patient and procedural characteristics and postoperative mortality and morbidity were subsequently centrally collected and systematically entered in a database. Univariate and multivariate logistic regression were performed associating variables with postoperative spinal cord ischemia (SCI). RESULTS Seventy-two patients were identified that underwent TEVAR after prior AAA repair. The risk of SCI was 12.5% (n = 9) and significantly higher than the 1.7% risk of SCI in patients without prior AAA repair (relative risk [RR] 7.2, 95% confidence interval [CI] 2.6 to 19.6, P < .0001). Symptoms of SCI completely resolved in 4 patients with prior AAA repair. Univariate analysis demonstrated that the following variables were significant predictors of SCI in patients with prior AAA repair: preoperative renal insufficiency (odds ratio [OR] 29.5; 95% CI 5.3-164, P < .001), increased length of aorta coverage by TEVAR (OR 1.1; 95% CI 1.0-1.2, P .039) and a lengthened time interval between prior AAA repair and TEVAR (OR 1.2; 95% CI 1.0-1.4, P .026). Preoperative renal insufficiency was also significantly associated with the risk of SCI in multivariate analysis (P .011). CONCLUSION Prior infrarenal AAA repair is associated with dramatic increased risk of SCI after TEVAR compared to patients without prior AAA surgery. Preoperative renal insufficiency appears to be an important predictor of SCI after TEVAR in patients with prior AAA repair. A thorough understanding of the risk profile in patients requiring TEVAR following prior AAA surgery is essential when determining appropriate surgical recommendations. If the diameter and rupture risk are large and TEVAR is indicated, the best available care should be offered for maximal protection of the spinal cord in these patients.

Potential Value of Aneurysm Sac Volume Measurements in Addition to Diameter Measurements after Endovascular Aneurysm Repair

Purpose: To investigate the value of aneurysm sac volume measurement in addition to diameter measurements based on computed tomographic angiography (CTA) after endovascular aneurysm repair (EVAR). Methods: Interrogation of a vascular database identified 56 patients (51 men; median age 77 years, range 59–92), 28 with an endoleak and 28 without, who had digital CTA data available at baseline (first postoperative scan) and at 1 and 2 years after EVAR. Total aneurysm volume, transverse maximum diameter (TMD), and orthogonal maximum diameter (OMD; perpendicular to the aortic center lumen line) were compared for all patients and between those with and without endoleak. Differences of 5% for volume and 5 mm for diameters were considered a significant change. Kappa statistics were used to compare measurements. Results: Volumetry detected aneurysm growth in 32 (24%) of 131 scans, which was reflected by TMD in 12 (38%) and by OMD in 14 (44%). Eighteen scans with increasing aneurysm volume were measured in patients with endoleaks, which was documented by TMD in 6 (33%) and by OMD in 8 (44%). Fourteen volume increases were measured in patients without endoleak; both TMD and OMD documented only 43%. Volumetry detected aneurysm shrinkage in 71 (54%) of 131 scans [detected by TMD in 38 (54%) and by OMD in 37 (52%)]. Thirty-two volume decreases were measured in patients with an endoleak, noted by TMD in 18 (56%) and OMD in 14 (44%). Thirty-nine scans showed decreasing volumes in patients without endoleaks; the TMD corresponded in 20 (51%) and the OMD in 23 (59%). The kappa agreements for volume increase were 0.42 (TMD) and 0.35 (OMD) and for volume decrease 0.48 (TMD) and 0.47 (OMD); different thresholds of change produced similar moderate-range kappa values (0.3–0.6). Conclusion: Volumetry detects sac size changes that are not reflected in diameter measurements. Vice versa, diameters can increase without a total volume increase, which might indicate a variety of morphological aneurysm changes. The agreement between volume and diameter measurements using different cutoff values is equally moderate. Volume measurements should be performed in addition to diameter measurements.