Detection of Pulmonary Embolism During Cardiac Arrest-Ultrasonographic Findings Should Be Interpreted With Caution.

OBJECTIVES: The aim of this study was to test the hypothesis that the right ventricle is more dilated during resuscitation from cardiac arrest caused by pulmonary embolism, compared with hypoxia and primary arrhythmia. DESIGN: Twenty-four pigs were anesthetized and cardiac arrest was induced using three different methods. Pigs were resuscitated after 7 minutes of untreated cardiac arrest. Ultrasonographic images were obtained and the right ventricular diameter was measured. SETTING: University hospital animal laboratory. SUBJECTS: Female crossbred Landrace/Yorkshire/Duroc pigs (27-32 kg). INTERVENTIONS: Pigs were randomly assigned to cardiac arrest induced by pulmonary embolism, hypoxia, or primary arrhythmia. MEASUREMENTS AND MAIN RESULTS: There was no difference at baseline. During induction of cardiac arrest, the right ventricle dilated in all groups (p < 0.01 for all). The primary endpoint was right ventricle diameter at the third rhythm analysis: 32 mm (95% CI, 29-36) for pulmonary embolism which was significantly larger than both hypoxia: 23 mm (95% CI, 20-27) and primary arrhythmia: 25 mm (95% CI, 22-28)-the absolute difference was 7-9 mm. Physicians with basic training in focused cardiac ultrasonography were able to detect a difference in right ventricle diameter of approximately 10 mm with a sensitivity of 79% (95% CI, 64-94) and a specificity of 68% (95% CI, 56-80). CONCLUSIONS: The right ventricle was more dilated during resuscitation when cardiac arrest was caused by pulmonary embolism compared with hypoxia and primary arrhythmia. However, the right ventricle was dilated, irrespective of the cause of arrest, and diagnostic accuracy by physicians with basic training in focused cardiac ultrasonography was modest. These findings challenge the paradigm that right ventricular dilatation on ultrasound during cardiopulmonary resuscitation is particularly associated with pulmonary embolism.

Stroke Related to Transcatheter Heart Valve Thrombosis.

Non-obstructive transcatheter heart valve (THV) thrombosis as a potential mechanism after stroke after transapical transcatheter aortic valve replacement (TAVR) is demonstrated by the present case report. By performing cardiac computed tomography (CT) in addition to standard transthoracic echocardiography (TTE) follow up after TAVR, it has been shown recently that non-obstructive THV thrombosis may be more common than previously anticipated. However, the clinical implications of non-obstructive THV thrombosis remain unclear. In the present patient, post-TAVR TTE and transeophageal echocardiography demonstrated normal THV function, and showed no evidence of THV thrombosis. In contrast, cardiac CT revealed findings consistent with THV thrombosis. The patient subsequently developed acute ischemic stroke that was treated with thrombolysis. Follow up cardiac CT and echocardiography demonstrated complete THV thrombus resolution.

Anatomical and procedural features associated with aortic root rupture during balloon-expandable transcatheter aortic valve replacement.

BACKGROUND: Aortic root rupture is a major concern with balloon-expandable transcatheter aortic valve replacement (TAVR). We sought to identify predictors of aortic root rupture during balloon-expandable TAVR by using multidetector computed tomography. METHODS AND RESULTS: Thirty-one consecutive patients who experienced left ventricular outflow tract (LVOT)/annular/aortic contained/noncontained rupture during TAVR were collected from 16 centers. A caliper-matched sample of 31 consecutive patients without annular rupture, who underwent pre-TAVR multidetector computed tomography served as a control group. Multidetector computed tomography assessment included short- and long-axis diameters and cross-sectional area of the sinotubular junction, annulus, and LVOT, and the presence, location, and extent of calcification of the LVOT, as well. There were no significant differences between the 2 groups in any preoperative clinical and echocardiographic variables. Aortic root rupture was identified in 20 patients and periaortic hematoma in 11. Patients with root rupture had a higher degree of subannular/LVOT calcification quantified by the Agatston score (181.2±211.0 versus 22.5±37.6, P<0.001), and a higher frequency of ≥20% annular area oversizing (79.4% versus 29.0%, P<0.001) and balloon postdilatation (22.6% versus 0.0%, P=0.005). In conditional logistic regression analysis for the matched data, moderate/severe LVOT/subannular calcifications (odds ratio, 10.92; 95% confidence interval, 3.23-36.91; P<0.001) and prosthesis oversizing ≥20% (odds ratio, 8.38; 95% confidence interval, 2.67-26.33; P<0.001) were associated with aortic root contained/noncontained rupture. CONCLUSIONS: This study demonstrates that LVOT calcification and aggressive annular area oversizing are associated with an increased risk of aortic root rupture during TAVR with balloon-expandable prostheses. Larger studies are warranted to confirm these findings.

Three-dimensional multidetector computed tomography versus conventional 2-dimensional transesophageal echocardiography for annular sizing in transcatheter aortic valve replacement: Influence on postprocedural paravalvular aortic regurgitation.

OBJECTIVES: In transcatheter aortic valve replacement (TAVR), the influence of aortic annular assessment with either multidetector computed tomography (MDCT) or conventional transesophageal echocardiography (TEE) on the incidence of postprocedural paravalvular aortic regurgitation (PAR) was evaluated. BACKGROUND: PAR remains a major limitation in TAVR. Appropriate selection of transcatheter heart valve (THV) size is crucial to prevent PAR. METHODS: Outcomes following TAVR with a balloon-expandable THV were compared in two retrospective cohorts identified according to whether THV size selection was based on TEE (study group 1, n = 80) or MDCT (study group 2, n = 58). RESULTS: The two study groups were comparable with regard to baseline clinical, risk score, and echocardiographic characteristics. The incidence of moderate/severe PAR was lower in study group 2 than in group 1, 8.6% versus 28.8% (P < 0.01). The difference between the THV nominal diameter and MDCT annular diameter was predictive of moderate/severe PAR (AUC 0.84; 95% CI: 0.72-0.92). Neither age, gender, body mass index, annular eccentricity index, aortic valve calcification nor the difference between the THV diameter and the TEE annular diameter predicted postprocedural PAR. Increased THV oversizing relative to the MDCT mean annular diameter was associated with reduced severity of PAR. No difference in perprocedural complications between two study groups was observed. CONCLUSION: MDCT-based annular sizing in TAVR significantly reduces postprocedural PAR, and THV oversizing appears pivotal in this aspect. Further delineation of the optimal degree of THV oversizing is needed.

Subclinical leaflet thrombosis after transcatheter aortic valve implantation: no association with left ventricular reverse remodeling at 1-year follow-up.

Hypo-attenuated leaflet thickening (HALT) of transcatheter aortic valves is detected on multidetector computed tomography (MDCT) and reflects leaflet thrombosis. Whether HALT affects left ventricular (LV) reverse remodeling, a favorable effect of LV afterload reduction after transcatheter aortic valve implantation (TAVI) is unknown. The aim of this study was to examine the association of HALT after TAVI with LV reverse remodeling. In this multicenter case-control study, patients with HALT on MDCT were identified, and patients without HALT were propensity matched for valve type and size, LV ejection fraction (LVEF), sex, age and time of scan. LV dimensions and function were assessed by transthoracic echocardiography before and 12 months after TAVI. Clinical outcomes (stroke or transient ischemic attack, heart failure hospitalization, new-onset atrial fibrillation, all-cause mortality) were recorded. 106 patients (age 81 ± 7 years, 55% male) with MDCT performed 37 days [IQR 32-52] after TAVI were analyzed (53 patients with HALT and 53 matched controls). Before TAVI, all echocardiographic parameters were similar between the groups. At 12 months follow-up, patients with and without HALT showed a significant reduction in LV end-diastolic volume, LV end-systolic volume and LV mass index (from 125 ± 37 to 105 ± 46 g/m2, p = 0.001 and from 127 ± 35 to 101 ± 27 g/m2, p < 0.001, respectively, p for interaction = 0.48). Moreover, LVEF improved significantly in both groups. In addition, clinical outcomes were not statistically different. Improvement in LVEF and LV reverse remodeling at 12 months after TAVI were not limited by HALT.

Aortic valve and left ventricular outflow tract calcium volume and distribution in transcatheter aortic valve replacement: Influence on the risk of significant paravalvular regurgitation.

OBJECTIVES: We sought to determine the impact of aortic root calcium on the risk of significant paravalvular regurgitation (sPAR) in transcatheter aortic valve replacement (TAVR). METHODS: In 302 consecutive patients from 3 centers, aortic root calcium was quantified volumetrically on pre-TAVR multidetector computed tomography (MDCT) in three regions: 1) the aortic valve region, 2) the overall left ventricular outflow tract (LVOT) and 3) the upper LVOT. Transcathether heart valve (THV) oversizing was calculated as (THV nominal area/MDCT annular area-1) × 100. The study endpoint sPAR was a composite of post-dilatation (PD) and PAR > mild. RESULTS: sPAR occurred in 15% (46/302) of patients. Upper LVOT calcium volume was more predictive of sPAR than overall LVOT calcium volume, with an area under the receiver operating curve (AUC) (95% confidence interval [CI]) of 0.80 (0.67-0.89) vs. 0.60 (0.51-0.70); p = 0.0001. The optimal cut-off calcium volume thresholds determined from receiver operating curves were 21 mm3 and 30 mm3 for upper LVOT and overall LVOT calcium, respectively. Upper LVOT calcium ≥ 21 mm3, but not overall LVOT calcium ≥ 30 mm3, independently predicted sPAR, odds ratio (95%CI): 9.5 (4.1-22.3) vs 1.6 (0.6-2.7). Upper LVOT calcium was more predictive of sPAR in patients with THV oversizing ≥ 13% compared to patients with THV oversizing <13%, AUC (95% CI): 0.83 (0.72-0.93) vs. 0.67 (0.51-0.74); p < 0.0001. CONCLUSIONS: Upper LVOT calcium predicts more-than-mild paravalvular regurgitation following TAVR or the need for postdilatation. Upper LVOT calcium is most predictive of paravalvular regurgitation in the event of THV oversizing ≥ 13%.

Transcatheter Aortic Valve Thrombosis: Incidence, Predisposing Factors, and Clinical Implications.

BACKGROUND: There are limited data on the incidence, clinical implications, and predisposing factors of transcatheter heart valve (THV) thrombosis following transcatheter aortic valve replacement (TAVR). OBJECTIVES: The authors assessed the incidence, potential predictors, and clinical implications of THV thrombosis as determined by contrast-enhanced multidetector computed tomography (MDCT) after TAVR. METHODS: Among 460 consecutive patients who underwent TAVR with the Edwards Sapien XT or Sapien 3 (Edwards Lifesciences, Irvine, California) THV, 405 (88%) underwent MDCT in addition to transthoracic and transesophageal echocardiography 1 to 3 months post-TAVR. MDCT scans were evaluated for hypoattenuated leaflet thickening that indicated THV thrombosis. RESULTS: MDCT verified THV thrombosis in 28 of 405 (7%) patients. A total of 23 patients had subclinical THV thrombosis, whereas 5 (18%) patients experienced clinically overt obstructive THV thrombosis. THV thrombosis risk did not differ among different generations of THVs (8% vs. 6%; p = 0.42). The risk of THV thrombosis in patients who did not receive warfarin was higher compared with patients who received warfarin (10.7% vs. 1.8%; risk ratio [RR]: 6.09; 95% confidence interval [CI]: 1.86 to 19.84). A larger THV was associated with an increased risk of THV thrombosis (p = 0.03). In multivariable analysis, a 29-mm THV (RR: 2.89; 95% CI: 1.44 to 5.80) and no post-TAVR warfarin treatment (RR: 5.46; 95% CI: 1.68 to 17.7) independently predicted THV thrombosis. Treatment with warfarin effectively reverted THV thrombosis and normalized THV function in 85% of patients as documented by follow-up transesophageal echocardiography and MDCT. CONCLUSIONS: Incidence of THV thrombosis in this large study was 7%. A larger THV size may predispose to THV thrombosis, whereas treatment with warfarin appears to have a protective effect. Although often subclinical, THV thrombosis may have important clinical implications.

A "normal" invasive coronary angiogram may not be normal.

In clinical practice, a normal or near-normal invasive coronary angiogram is considered to be reliable evidence for the absence of hemodynamically significant coronary artery disease. We present 2 patients with near-normal coronary angiograms who had noninvasive evidence of vessel-specific ischemia confirmed by invasive measurement of fractional flow reserve.

Early aortic transcatheter heart valve thrombosis: diagnostic value of contrast-enhanced multidetector computed tomography.

BACKGROUND: Early stent valve thrombosis after transcatheter aortic valve implantation (TAVI) is a rare complication, which is diagnosed based on the appearance of clinical symptoms of heart failure and echocardiographic findings. After TAVI, transthoracic echocardiography is performed to assess transcatheter heart valve (THV) function. However, preliminary reports indicate the potential additive clinical value of multidetector computed tomography (MDCT) for the diagnosis of THV thrombosis. We sought to determine the value of MDCT for the diagnosis of THV thrombosis and the frequency of this complication after balloon-expandable TAVI. METHODS AND RESULTS: MDCT was performed in 140 patients within 1 to 3 months after TAVI with the Edwards Sapien XT THV to assess the presence of THV thrombosis and THV stent geometry. Post-TAVI MDCT identified THV thrombosis in 5 patients (4%). Of note, 4 of these patients were asymptomatic and had a normal transthoracic echocardiographic examination without signs of thrombus formation or flow obstruction. In patients with THV thrombosis, a left ventricular ejection fraction of <35% was present in 3 (60%), whereas 2 (40%) did not receive standard post-TAVI dual-antiplatelet therapy. Neither THV underexpansion nor THV noncircularity was detected in patients with THV thrombosis. CONCLUSIONS: Post-TAVI MDCT is a valuable tool for the diagnosis of THV thrombosis, and this complication seems to be more common than previously anticipated. Larger studies are required to identify specific risk factors of THV thrombosis.

A Strategy of Underexpansion and Ad Hoc Post-Dilation of Balloon-Expandable Transcatheter Aortic Valves in Patients at Risk of Annular Injury: Favorable Mid-Term Outcomes.

OBJECTIVES: The aim of this study was to evaluate a strategy of intentional underexpansion of excessively oversized balloon-expandable transcatheter heart valves (THVs) in terms of clinical outcomes, valve function, and frame durability at 1 year. BACKGROUND: Transcatheter aortic valve replacement requires the selection of an optimally sized THV to ensure paravalvular sealing and fixation without risking annular injury. However, some patients have "borderline" annular dimensions that require choosing between a THV that may be too small or another that may be too large. METHODS: We evaluated 47 patients at risk of annular injury who underwent transcatheter aortic valve replacement (TAVR) with an oversized, but deliberately underexpanded, THV followed by post-dilation if required. Clinical evaluation, echocardiography, and cardiac computed tomography were performed pre-TAVR, post-TAVR, and at 1 year. RESULTS: Deployment of oversized THVs with modest underfilling of the deployment balloon (<10% by volume) was not associated with significant annular injury. Paravalvular regurgitation was mild or less in 95.7% of patients, with post-dilation required in 10.7%. THV hemodynamic function was excellent and remained stable at 1 year. Computed tomography documented stent frame circularity in 87.5%. Underexpansion was greatest within the intra-annular THV inflow (stent frame area 85.8% of nominal). There was no evidence of stent frame recoil, deformation, or fracture at 1 year. CONCLUSIONS: In carefully selected patients with borderline annulus dimensions and in whom excessive oversizing of a balloon-expandable SAPIEN XT valve (Edwards Lifesciences, Inc., Irvine, California) is a concern, a strategy of deliberate underexpansion, with ad hoc post-dilation, if necessary, may reduce the risk of annular injury without compromising valve performance.

Incidence and severity of paravalvular aortic regurgitation with multidetector computed tomography nominal area oversizing or undersizing after transcatheter heart valve replacement with the Sapien 3: a comparison with the Sapien XT.

OBJECTIVES: This study sought to compare the influence of the extent of multidetector computed tomography (MDCT) area oversizing on the incidence of paravalvular aortic regurgitation (PAR) between the Sapien 3 and the Sapien XT transcatheter heart valve (THV) to define a new MDCT sizing guideline suitable for the Sapien 3 platform. BACKGROUND: The inverse relationship of PAR occurrence and oversizing has been demonstrated for the Sapien XT but the incidence of PAR with comparable oversizing with the Sapien 3 is not known. METHODS: Sixty-one prospectively enrolled patients who underwent transcatheter aortic valve replacement with the Sapien 3 THV were compared with 92 patients who underwent transcatheter aortic valve replacement with the Sapien XT THV. Patients were categorized depending on the degree of MDCT area oversizing percentage: undersizing (below 0%), 0% to 5%, 5% to 10%, and above 10%. The primary endpoint was mild or greater PAR on transthoracic echocardiography. RESULTS: Mild or greater PAR was present in 19.7% of patients (12 of 61) in the Sapien 3 group and in 54.3% of patients (50 of 92) in the Sapien XT group (p < 0.01). The Sapien 3 group, compared with the Sapien XT group, consistently demonstrated significantly lower rates of mild or greater PAR except for oversizing >10% (p for interaction = 0.54). Moderate or severe PAR rates were also lower in the Sapien 3 group than in the Sapien XT group (3.3% vs. 13.0%, p = 0.04). In the Sapien 3 group, a MDCT area oversizing percentage value of ≤4.17% was identified as the optimal cutoff value to discriminate patients with or without mild or greater PAR. CONCLUSIONS: Our retrospective analysis suggests that the Sapien 3 THV displays significantly lower rates of PAR than does the Sapien XT THV. A lesser degree of MDCT area oversizing may be employed for this new balloon-expandable THV.

The impact of calcium volume and distribution in aortic root injury related to balloon-expandable transcatheter aortic valve replacement.

BACKGROUND: A detailed assessment of calcium within the aortic root may provide important additional information regarding the risk of aortic root injury during transcatheter heart valve replacement (TAVR). OBJECTIVE: We sought to delineate the effect of calcium volume and distribution on aortic root injury during TAVR. METHODS: Thirty-three patients experiencing aortic root injury during TAVR with a balloon-expandable valve were compared with a control group of 153 consecutive TAVR patients without aortic root injury (as assessed by post-TAVR multidetector CT). Using commercial software to analyze contrast-enhanced pre-TAVR CT scans, calcium volume was determined in 3 regions: (1) the overall left ventricular outflow tract (LVOT), extending 10 mm down from the aortic annulus plane; (2) the upper LVOT, extending 2 mm down from the annulus plane; and (3) the aortic valve region. RESULTS: Calcium volumes in the upper LVOT (median, 29 vs 0 mm(3); P < .0001) and overall LVOT (median, 74 vs 3 mm(3); P = .0001) were higher in patients who experienced aortic root injury compared with the control group. Calcium in the aortic valve region did not differ between groups. Upper LVOT calcium volume was more predictive of aortic root injury than overall LVOT calcium volume (area under receiver operating curve [AUC], 0.78; 95% confidence interval, 0.69-0.86 vs AUC, 0.71; 95% confidence interval, 0.62-0.82; P = .010). Upper LVOT calcium below the noncoronary cusp was significantly more predictive of aortic root injury compared to calcium underneath the right coronary cusp or the left coronary cusp (AUC, 0.81 vs 0.68 vs 0.64). Prosthesis oversizing >20% (likelihood ratio test, P = .028) and redilatation (likelihood ratio test, P = .015) improved prediction of aortic root injury by upper LVOT calcium volume. CONCLUSION: Calcification of the LVOT, especially in the upper LVOT, located below the noncoronary cusp and extending from the annular region, is predictive of aortic root injury during TAVR with a balloon-expandable valve.

Multidetector CT predictors of prosthesis-patient mismatch in transcatheter aortic valve replacement.

BACKGROUND: Prosthesis-patient mismatch (PPM) is a predictor of mortality after aortic valve replacement (AVR). OBJECTIVE: We examined whether accurate 3-dimensional annular sizing with multidetector CT (MDCT) is predictive of PPM after transcatheter AVR (TAVR). METHODS: One hundred twenty-eight patients underwent MDCT then TAVR. Moderate PPM was defined as an indexed effective orifice area ≤0.85 cm²/m² and severe ≤0.65 cm²/m². MDCT annular measurements (area, short and long axis) were compared with the size of the selected transcatheter heart valve (THV) to obtain (1) the difference between prosthesis size and CT-measured mean annular diameter and (2) the percentage of undersizing or oversizing (calculated as 100 × [MDCT annular area--THV nominal area]/THV nominal area). In addition, the MDCT annular area was indexed to body surface area. These measures were evaluated as potential PPM predictors. RESULTS: We found that 42.2% of patients had moderate PPM and 9.4% had severe PPM. Procedural characteristics and in-hospital outcomes were similar between patients with or without PPM. THV undersizing of the mean aortic annulus diameter was not predictive of PPM (odds ratio [OR], 0.84; 95% CI, 0.65-1.07; P = .16; area under the receiver-operating characteristic curve [AUC], 0.58). THV undersizing of annular area was not predictive of PPM (OR, 0.96; 95% CI, 0.80-1.16; P = .69; AUC, 0.52). Indexed MDCT annular area was, however, predictive of PPM (OR, 0.24; 95% CI, 0.10-0.59; P < .001; AUC, 0.66). CONCLUSIONS: PPM is frequent after TAVR. Appropriate annular oversizing does not reduce the rate or severity of PPM. Patient annulus size mismatch, identified by indexed MDCT annular area, is a significant predictor of PPM.

The impact of integration of a multidetector computed tomography annulus area sizing algorithm on outcomes of transcatheter aortic valve replacement: a prospective, multicenter, controlled trial.

OBJECTIVES: This study prospectively investigated the impact of integration of a multidetector computed tomography (MDCT) annular area sizing algorithm on transcatheter aortic valve replacement (TAVR) outcomes. BACKGROUND: Appreciation of the 3-dimensional, noncircular geometry of the aortic annulus is important for transcatheter heart valve (THV) sizing. METHODS: Patients being evaluated for TAVR in 4 centers underwent pre-procedural MDCT. Recommendations for balloon-expandable THV size selection were based on an MDCT sizing algorithm with an optimal goal of modest annulus area oversizing (5% to 10%). Consecutive patients who underwent TAVR with the algorithm (MDCT group) were compared with consecutive patients without the algorithm (control group). The primary endpoint was the incidence of more than mild paravalvular regurgitation (PAR), and the secondary endpoint was the composite of in-hospital death, aortic annulus rupture, and severe PAR. RESULTS: Of 266 patients, 133 consecutive patients underwent TAVR (SAPIEN XT THV) in the MDCT group and 133 consecutive patients were in the control group. More than mild PAR was present in 5.3% (7 of 133) of the MDCT group and in 12.8% (17 of 133) in the control group (p = 0.032). The combined secondary endpoint occurred in 3.8% (5 of 133) of the MDCT group and in 11.3% (15 of 133) of the control group (p = 0.02), driven by the difference of severe PAR. CONCLUSIONS: The implementation of an MDCT annulus area sizing algorithm for TAVR reduces PAR. Three-dimensional aortic annular assessment and annular area sizing should be considered for TAVR.

Antiatherogenic effects of oleanolic acid in apolipoprotein E knockout mice.

Oleanolic acid (OA) is a plant triterpenoid steroid with potentially antiatherogenic properties. We investigated whether OA affected atherosclerosis development and vascular function in apolipoprotein E knockout (ApoE(-/-)) mice. ApoE(-/-) mice were fed a high cholesterol Western-type diet in combination with OA (100 mg/kg/day), fluvastatin (5 mg/kg/day) or vehicle, with wild type (WT) mice serving as controls. After 8 weeks of treatment atherosclerotic plaque areas in the aortic arch and plasma lipid concentrations were determined. Vasoconstriction and relaxation of the proximal part of aorta were investigated in vitro. Inducible nitric oxide synthase (iNOS) was visualized using immunoblotting. As opposed to WT and fluvastatin- and vehicle-treated mice, OA-fed ApoE(-/-) mice gained no weight during the treatment period. Plasma concentrations of total-cholesterol and triglyceride were not significantly reduced by OA- or fluvastatin treatment. Plaque area of vehicle-treated mice was 25%, but only 14% in OA- and 19% in fluvastatin-treated mice. As compared to WT, vasoconstriction to phenylephrine was attenuated in ApoE(-/-) mice. The NOS inhibitor asymmetric dimethylarginine (ADMA) enhanced phenylephrine constriction, but significantly more so in vehicle- and fluvastatin-treated than in OA-treated and WT mice. Relaxation to acetylcholine was only slightly attenuated in ApoE(-/-) mice and not affected by OA or fluvastatin treatment. ADMA abolished acetylcholine relaxation almost completely. In ApoE(-/-) mice iNOS expression was reduced by OA treatment. In conclusion OA exerts potent antiatherogenic effects independent of plasma lipid levels and without major changes in eNOS-mediated acetylcholine relaxation. However, OA reduced iNOS expression possibly altering vascular reactivity to phenylephrine.