Transcatheter heart valve explant with infective endocarditis-associated prosthesis failure and outcomes: the EXPLANT-TAVR international registry.

BACKGROUND AND AIMS: Surgical explantation of transcatheter heart valves (THVs) is rapidly increasing, but there are limited data on patients with THV-associated infective endocarditis (IE). This study aims to assess the outcomes of patients undergoing THV explant for IE. METHODS: All patients who underwent THV explant between 2011 and 2022 from 44 sites in the EXPLANT-TAVR registry were identified. Patients with IE as the reason for THV explant were compared to those with other mechanisms of bioprosthetic valve dysfunction (BVD). RESULTS: A total of 372 patients from the EXPLANT-TAVR registry were included. Among them, 184 (49.5%) patients underwent THV explant due to IE and 188 (50.5%) patients due to BVD. At the index transcatheter aortic valve replacement, patients undergoing THV explant for IE were older (74.3 ± 8.6 vs. 71 ± 10.6 years) and had a lower Society of Thoracic Surgeons risk score [2.6% (1.8-5.0) vs. 3.3% (2.1-5.6), P = .029] compared to patients with BVD. Compared to BVD, IE patients had longer intensive care unit and hospital stays (P < .05) and higher stroke rates at 30 days (8.6% vs. 2.9%, P = .032) and 1 year (16.2% vs. 5.2%, P = .010). Adjusted in-hospital, 30-day, and 1-year mortality was 12.1%, 16.1%, and 33.8%, respectively, for the entire cohort, with no significant differences between groups. Although mortality was numerically higher in IE patients 3 years postsurgery (29.6% for BVD vs. 43.9% for IE), Kaplan-Meier analysis showed no significant differences between groups (P = .16). CONCLUSIONS: In the EXPLANT-TAVR registry, patients undergoing THV explant for IE had higher 30-day and 1-year stroke rates and longer intensive care unit and hospital stays. Moreover, patients undergoing THV explant for IE had a higher 3-year mortality rate, which did not reach statistical significance given the relatively small sample size of this unique cohort and the reduced number of events.

Impact of preoperative Impella support on destination left ventricular assist device outcomes.

BACKGROUND: Although left ventricular assist device (LVAD) implantation is associated with improved heart failure survival, the impact of pre-implantation Impella support on outcomes is unknown. We undertook this study to evaluate the impact of preoperative Impella support on LVAD outcomes. METHODS: We conducted a retrospective review of all Heartmate 3 LVAD implants. Primary stratification was by the need for preoperative Impella support with the 5.0/5.5 device. Longitudinal survival was assessed by the Kaplan-Meier method. Multivariable Cox proportional hazards regression models were developed to evaluate mortality. Secondary outcomes included changes in laboratory values during Impella support. RESULTS: From 2017 to 2021, 87 patients underwent LVAD implantation. Sixteen were supported with a single inotrope, 36 with dual inotropes, 27 with Impella, and 3 with extracorporeal membrane oxygenation (ECMO). When stratified by the need for Impella, there was no difference in survival at 30-days (98.3 [88.2-99.8]% vs. 96.3 [76.5-99.5]%, p = .59), 1-year (91.0 [79.8-96.2] vs. 74.9 [51.7-88.2], p = .10), or at 2 years (87.9 [74.3-94.5] vs. 74.9 [51.7-88.2], p = .15). On multivariable modeling, the need for preoperative Impella was not associated with an increased hazard of 1-year (1.24 [0.23-6.73], p = .81) or 2-year mortality (1.05 [0.21-5.19], p = .95). After 7 (5-10) days of Impella support, recipient creatinine (p < .01), creatinine clearance (p = .02), and total bilirubin (p = .053) improved and lactic acidosis resolved (p < .01). CONCLUSIONS: Preoperative Impella support is not associated with increased short or long-term mortality but is associated with improved renal and hepatic function as well as total body perfusion before LVAD implantation.

Outcomes of aortic root enlargement during isolated aortic valve replacement.

OBJECTIVES: Aortic root enlargement (ARE) lowers the risk of patient prosthesis mismatch after surgical aortic valve replacement (SAVR) in patients with small annular size. Whether ARE is associated with increased operative mortality is controversial. This study compares the early and intermediate outcomes in patients undergoing SAVR with and without ARE. METHODS: All patients undergoing isolated SAVR with and without ARE from 2015 to 2020 were analyzed. Propensity-matching was used to adjust for possible confounding variables. Kaplan-Meier analysis and log-rank test were used to estimate and compare overall outcomes and survival in the study cohorts. RESULTS: Among 868 isolated SAVRs, ARE was performed in 54 (6.2%) patients. Before matching, mean age was similar but female sex (67.4% vs. 29.6%; SD: -0.82) and previous AVR (18.9% vs. 3.9%; SD: -0.48) were more common in patients undergoing SAVR + ARE versus SAVR alone. A bovine pericardial patch was used for 81.5% (44 of 54) of ARE, with a Dacron patch in the rest. After propensity matching, the average cardiopulmonary bypass (138.2 ± 34.9 vs. 102.9 ± 33.0 min; p < 0.01) and cross-clamp times (113.8 ± 26.7 vs. 83.0 ± 28.4 min; p < 0.01) were longer in the SAVR + ARE group. There were no significant differences in postoperative stroke, new-onset dialysis, pacemaker placement, reoperation for bleeding, length of hospital stay, or 30-day readmission. Thirty-day mortality (0% vs. 0.6%, p = 1.0) and 5-year survival (96.3% vs. 95.7%, p = 0.86) were also similar. CONCLUSIONS: ARE during surgical AVR can be safely performed without an increase in complications with excellent early and intermediate-term survival.

Congenital anomalies of the aortic arch in acute type-a aortic dissection: implications for monitoring, perfusion strategy, and surgical repair.

OBJECTIVE: To assess whether management of acute Stanford type-A aortic dissection differs in patients with congenital anomalies of the aortic arch compared with standard institutional practice. DESIGN: Retrospective analysis of all consecutive patients from 2001 through 2011. SETTING: Quaternary referral center for surgical management of thoracic aortic disease. PARTICIPANTS: All patients with arch anomalies who underwent surgery for acute Stanford type-A aortic dissection during the study period (n = 43). INTERVENTIONS: Surgical management, anesthetic monitoring, and perfusion strategy were analyzed in a retrospective fashion. No new interventions were undertaken as part of this study. MEASUREMENTS AND MAIN RESULTS: Management differed most in patients with an aberrant right subclavian artery (n = 5), because the institutional standard of right axillary artery cannulation with left upper extremity arterial pressure monitoring was not possible. In patients with one of two "bovine" arch patterns (n = 32), management differed in the conduct of selective antegrade cerebral perfusion, which could include clamping above or below the takeoff of the left common carotid artery (and, therefore, produced unilateral or bilateral antegrade cerebral perfusion). All patients with a connective tissue disorder exhibited a bovine arch pattern. Management of patients with a right arch (n = 3) reflected the opposite of management for normal anatomy (for patients with traditional mirror-image branching) or opposite that of the aberrant right subclavian group (for patients who had a corresponding aberrant left subclavian artery). CONCLUSIONS: Rational management reflected the anatomic variations observed. These results support the importance of interdisciplinary planning, especially in an emergency, to optimize outcome.

Midterm durability of valve-sparing root replacement in bicuspid and tricuspid aortic valves.

Background: Among patients with bicuspid aortic valves (BAV) who are potential candidates for valve-sparing root replacement (VSRR), the long-term durability of this technique is not well understood. This study aimed to compare the clinical and echocardiographic outcomes of VSRR in those with BAV and tricuspid aortic valve (TAV) morphology. Methods: This was a retrospective analysis of patients who underwent VSRR between 2007 and 2021 at a single center. Kaplan-Meier and log-rank analysis were used to estimate and compare freedom from mortality, progression to >2+ aortic insufficiency (AI), and reoperation between groups (BAV vs TAV). Preoperative and postoperative echocardiographic data were collected and assessed for temporal changes in mixed-effect models. Results: A total of 185 patients (BAV, n = 52, 28.1%; TAV, n = 133, 71.9%) underwent VSRR. At baseline, BAV patients were younger (42.4 ± 11.6 vs 52.3 ± 12.6 years; P < 0.01) and had more severe AI (47.9% vs 27.0%; P = 0.02). Average cardiopulmonary bypass and cross-clamp times were similar. There were no differences in rates of postoperative complications, intensive care unit or hospital days, or 30-day readmission. TAV patients' 1-, 5-, and 8-year survival rates were 99.2% [95% CI 97.8-100], 96.7% [93.5-99.9%], and 92.2% [85.6-99.3%], respectively. Overall, there were no differences between groups regarding freedom from mortality (P = 0.18), reoperation (P = 0.51), or recurrent >2+ AI (P = 0.97). . Conclusions: VSRR can be safely performed on patients with BAV and TAV morphology, yielding similar midterm freedom from mortality, recurrent >2+ AI, and reoperation. This technique should be considered in carefully selected patients with aortic root pathology and BAV anatomy when performed at experienced centers.

Outcomes of redo operations after the Ross procedure.

BACKGROUND: The Ross procedure is not commonly performed, owing to the procedural complexity and the risk of autograft and/or homograft reoperation. This study examined outcomes of patients undergoing Ross reinterventions at a dedicated Ross center. METHODS: We retrospectively reviewed 225 consecutive patients who underwent a Ross procedure between 1994 and 2019. Index and redo operation characteristics and outcomes were compared between patients with and those without redo operations. Multivariate analysis was used to identify independent predictors of Ross-related reinterventions. Survival was estimated with Kaplan-Meier analysis. RESULTS: Sixty-six patients (29.3%) required redo Ross surgery, 41 patients (18.2%) underwent autograft reoperation only, 8 patients (3.6%) had a homograft reintervention, and 17 patients (7.6%) had both autograft and homograft reoperations (12 as a combined procedure and 5 as sequential procedures). The mean time to reintervention was 11 ± 6 years for autograft reoperations and 12 ± 7 years for homograft reoperations. Patients who underwent Ross-related reinterventions were younger (mean, 38 ± 11 years vs 43 ± 11 years; P < .01) and had a higher rate of New York Heart Association class III/IV (56% vs 38%; P = .02) at the index Ross procedure. Most patients undergoing autograft reintervention had aortic insufficiency and/or aneurysm (98.2%; 57 of 58). The primary reason for homograft reintervention was pulmonary stenosis (92%; 23 of 25). The operative mortality of Ross reintervention was 1.5% (1 of 66). Survival at 15 years was similar in patients who required a redo operation and those who did not (91.2% vs 93.9%; P = .23). CONCLUSIONS: Ross reinterventions can be performed safely and maintain patients at the normal life expectancy restored by the index Ross procedure up to 15 years at experienced centers.

Race, neighborhood disadvantage, and survival of Medicare beneficiaries after aortic valve replacement and concomitant coronary artery bypass grafting.

BACKGROUND: Race, neighborhood disadvantage, and the interaction between these 2 social determinants of health remain poorly understood with regards to survival after aortic valve replacement with concomitant coronary artery bypass grafting (AVR+CABG). METHODS: Weighted Kaplan-Meier survival analyses and Cox proportional hazards modeling were used to evaluate the association between race, neighborhood disadvantage, and long-term survival in 205,408 Medicare beneficiaries undergoing AVR+CABG from 1999 to 2015. Neighborhood disadvantage was measured using the Area Deprivation Index, a broadly validated ranking of socioeconomic contextual disadvantage. RESULTS: Self-identified race was 93.9% White and 3.2% Black. Residents of the most disadvantaged quintile of neighborhoods included 12.6% of all White beneficiaries and 40.0% of all Black beneficiaries. Black beneficiaries and residents of the most disadvantaged quintile of neighborhoods had more comorbidities compared with White beneficiaries and residents of the least disadvantaged quintile of neighborhoods, respectively. Increasing neighborhood disadvantage linearly increased the hazard for mortality for Medicare beneficiaries of White but not Black race. Residents of the most and least disadvantaged neighborhood quintiles had weighted median overall survival of 93.0 and 82.1 months, respectively, a significant difference (P < .001 by Cox test for equality of survival curves). Black and White beneficiaries had weighted median overall survival of 93.4 and 90.6 months, respectively, a nonsignificant difference (P = .29 by Cox test for equality of survival curves). A statistically significant interaction between race and neighborhood disadvantage was noted (likelihood ratio test P = .0215) and had implications on whether Black race was associated with survival. CONCLUSIONS: Increasing neighborhood disadvantage was linearly associated with worse survival after combined AVR+CABG in White but not Black Medicare beneficiaries; race, however, was not independently associated with postoperative survival.

Outcomes of the Ross procedure in patients older versus younger than 50 years old.

OBJECTIVES: The Ross procedure is traditionally considered for young adult patients with aortic valve disease. This study compares long-term outcomes of patients undergoing the Ross procedure who are ≥50 and <50-years old. METHODS: Data were collected from 225 patients undergoing Ross procedure at a single centre from 1994 to 2019. Patients were categorized into younger (<50-years old; n = 156) and older (≥50-years old; n = 69) cohorts. Baseline demographics clinical outcomes were compared. RESULTS: The mean age was 36 ± 8.1 and 55 ± 4.2 years in the younger and older cohort, respectively. Both groups were predominantly male (58.5% vs 69.6%; P = 0.59). The younger group had a higher rate of aortic insufficiency (51% vs 26.1%; P < 0.01), and bicuspid aortic valve (81.4% vs 58.0%; P < 0.01). Aortic stenosis was more prevalent in the older cohort (25.6% vs 58.0%; P < 0.01). Operative mortality was acceptable in both groups (1.3% vs 4.3%; P = 0.15). Survival up to 10 years was not statistically different between 2 groups (96.2% vs 91.3% P = 0.16), whereas survival up to 15 years for younger patients was significantly higher (94.9% vs 85.5%; P = 0.03). After non-cardiac related deaths were excluded, survival up to 15 years (98.7% vs 91.3%; P = 0.02) was significantly lower than younger patients. In both groups, survival after the Ross procedure was similar to the age- and sex-matched US population. CONCLUSIONS: Survival up to 10 years after Ross procedure were similar, but up to 15 years was significantly higher in younger patients. The Ross procedure restored patients from both groups to expected survival. Our results suggest that at experienced centres, the Ross procedure is a safe and reasonable option for patients who are 50 years and older.

Effect of Preincisional Liposomal Bupivacaine Sternal Blockade on Poststernotomy Opioid Use.

BACKGROUND: Prolonged and excessive opioid use in the postoperative setting is associated with multiple complications. The use of regional analgesia may reduce postoperative opioid use. METHODS: In a placebo-controlled, double-blinded trial patients undergoing sternotomy were randomly assigned in a 1:1 ratio to receive either a liposomal bupivacaine parasternal block or a normal saline parasternal injection. The primary endpoint was total morphine milligram equivalents (MMEs) used in the immediate 72-hour postoperative period. Secondary endpoints were intraoperative opioid use, pain scores, time to reach recovery milestones, and incidence of postoperative complications. RESULTS: Twenty-five patients received a normal saline injection, and 27 patients received an anesthetic sternal block. Randomization achieved excellent balance in demographics and comorbidities between the groups. Total postoperative opioid requirements at 72 hours were similar between the treatment and control groups (25.8 ± 10.4 vs 29.4 ± 16.3 MMEs, P = .60). Intraoperative opioid requirements were also similar between the 2 groups (124.8 ± 222.5 vs 114.9 ± 148.0 MMEs, P = .86). Length of stay in the intensive care unit (3.4 ± 2.5 vs 3.5 ± 2.6 days, P = .86) and hospital (8.7 ± 5.0 vs 7.5 ± 3.0 days, P = .45), time until return of bowel function (3.7 ± 1.4 vs 3.3 ± 1.4 days, P = .42), incidence of postoperative atrial fibrillation (24% vs 22.2%, P = .88), and incidence of nausea (24% vs 33.3%, P = .46) were similar. CONCLUSIONS: Preincisional sternal blockade with liposomal bupivacaine did not reduce the amount of opioid medication administered to patients in the first 72 hours after sternotomy.

Long-term outcomes of the Ross procedure in adults.

BACKGROUND: The optimal aortic valve replacement for young and middle-aged adults remains elusive. Although several high-volume international centers and surgeons have demonstrated excellent long-term results with the pulmonary autograft (Ross procedure) in adult patients, current guidelines from the United States do not favor this technique. We evaluated long-term clinical and echocardiographic outcomes of adult patients undergoing the Ross procedure at our center. METHODS: A retrospective review of 225 consecutive adult patients undergoing the Ross procedure was completed. Kaplan-Meier analysis was performed to evaluate overall survival, which was then compared to an age- and sex-matched general population with the log-rank test. Accounting for death as a competing hazard, the cumulative incidence of reintervention and autograft or homograft dysfunction were estimated over the long-term. RESULTS: Mean age was 42±11 years, and 62 (28%) patients were at least 50 years old. A bicuspid aortic valve was present in 179 (80%) patients. The most common indications for surgery were aortic insufficiency (n=94, 43%), aortic stenosis (n=81, 36%), and mixed etiology (n=46, 21%). In-hospital mortality was 0.9%. Overall survival (with 95% confidence intervals) at 1-, 10- and 20-year was 97.8% (95.9-99.7%), 94.2% (91.0-97.4%), and 81.3% (74.8-88.3%), respectively. Overall survival approximated that of the general population (log-rank P=0.32). The cumulative incidence (with 95% confidence intervals) of any autograft or homograft reintervention at 10-, 15-, and 20-year was 16% (12-20%), 28% (21-35%), and 45% (36-54%), respectively. CONCLUSIONS: The Ross procedure restores a normal life expectancy to young and middle-aged adults with severe aortic valve disease. The need for reintervention increases steadily during the second decade after the Ross procedure, but less than half of patients require any reintervention for up to 20-year.

Myofiber angle distributions in the ovine left ventricle do not conform to computationally optimized predictions.

Recent computational models of optimized left ventricular (LV) myofiber geometry that minimize the spatial variance in sarcomere length, stress, and ATP consumption have predicted that a midwall myofiber angle of 20 degrees and transmural myofiber angle gradient of 140 degrees from epicardium to endocardium is a functionally optimal LV myofiber geometry. In order to test the extent to which actual fiber angle distributions conform to this prediction, we measured local myofiber angles at an average of nine transmural depths in each of 32 sites (4 short-axis levels, 8 circumferentially distributed blocks in each level) in five normal ovine LVs. We found: (1) a mean midwall myofiber angle of -7 degrees (SD 9), but with spatial heterogeneity (averaging 0 degrees in the posterolateral and anterolateral wall near the papillary muscles, and -9 degrees in all other regions); and (2) an average transmural gradient of 93 degrees (SD 21), but with spatial heterogeneity (averaging a low of 51 degrees in the basal posterior sector and a high of 130 degrees in the mid-equatorial anterolateral sector). We conclude that midwall myofiber angles and transmural myofiber angle gradients in the ovine heart are regionally non-uniform and differ significantly from the predictions of present-day computationally optimized LV myofiber models. Myofiber geometry in the ovine heart may differ from other species, but model assumptions also underlie the discrepancy between experimental and computational results. To test the predictive capability of the current computational model would we propose using an ovine specific LV geometry and comparing the computed myofiber orientations to those we report herein.

Development of Multiple Aortic Mycotic Aneurysms After Cardiac Catheterization.

A 71-year-old male with a past medical history of coronary artery bypass surgery developed multiple, infected pseudoaneurysms of the ascending aorta and aortic root 1 year after cardiac catheterization. He underwent aortic root replacement with a 24-mm homograft. Tissue culture from operative specimens revealed invasive Aspergillus fumigatus infection. He was treated with voriconazole for 3 months. After 1 year, he had no recurrence of symptoms, pseudoaneurysm, or fungal infection.

Pathologic confirmation of valve thrombosis detected by four-dimensional computed tomography following valve-in-valve transcatheter aortic valve replacement.

A major concern regarding transcatheter aortic valve replacement (TAVR) is leaflet thrombosis. Four-dimensional computed tomography (4D-CT) is the preferred imaging modality to evaluate patients with suspected valve thrombosis. To date, the abnormal findings visualized by 4D-CT suggestive of leaflet thrombosis have lacked pathologic confirmation from a surgically explanted valve in a surviving patient. Herein, we provide pathologic confirmation of thrombus formation following surgical explantation of a thrombosed TAVR prosthesis that was initially identified by 4D-CT.

Comparison of Outcomes of Operative Therapy for Acute Type A Aortic Dissections Provided at High-Volume Versus Low-Volume Medical Centers in North Texas.

Immediate surgery is standard therapy for acute type A aortic dissections (TAAD). Because of its low incidence, many smaller cardiac surgery programs do not routinely perform this procedure because it may negatively affect outcomes. Many high-risk, low-volume (LV) surgical procedures are now preferentially performed in reference centers. We compared the outcomes of surgery for TAAD in high-volume (HV) and LV centers in a single metropolitan area to determine the optimal setting for treatment. Thirty-five of the 37 cardiac surgery programs in the Dallas Ft. Worth metropolitan area participate in a regional consortium to measure outcomes collected in the Society of Thoracic Surgeons Adult Cardiac Database. From January 01, 2008, to December 31, 2014, 29 programs had treated TAAD. Those programs performing at least 100 operations for TAAD were considered HV centers and the others LV. Surgery for TAAD was performed in 672 patients over the 7-year study period with HV centers performing 469 of 672 (70%) of the operations. Despite similar preoperative characteristics, operative mortality was significantly lower in HV versus LV centers (14.1% vs 24.1%; p = 0.001). There was no significant difference in postoperative paralysis rates (2.6% vs 4.5%; p = 0.196), stroke rates (10.7% vs 9.4%; p = 0.623), or 30-day readmission rates (12.1% vs 15.5%; p = 0.292). An improved survival rate in HV centers was maintained over a 5-year follow-up period. Surgery for TAAD in a single large metropolitan area was most commonly performed in HV centers. In conclusion, the treatment of acute thoracic aortic dissection is recommended to be performed in reference centers because of lower early and midterm mortality.

Left ventricular volume shifts and aortic root expansion during isovolumic contraction.

BACKGROUND AND AIM OF THE STUDY: Aortic valve opening involves conformational changes of the aortic root, including the ventricular-aortic junction (VAJ), sinotubular junction (STJ), and cusps. Moreover, the aortic root is contiguous with the left ventricular outflow tract (LVOT), which changes diameter throughout the cardiac cycle. Aortic root expansion prior to valve opening facilitates outward displacement of aortic cusp attachments, which helps flatten the cusps, thereby reducing cusp stress and fatigue, ultimately enhancing functional valve durability. The mechanisms underlying aortic root expansion prior to valve opening, however, remain incompletely characterized. The study aim was to establish a link between such aortic root expansion and intraventricular volume shifts into the LVOT during isovolumic contraction (IVC). METHODS: Miniature radiopaque markers were implanted on the left ventricle, VAJ, STJ, and aortic cusps of six sheep. After one week, 3-D marker coordinates were obtained using biplane videofluoroscopy (60 Hz). Triangular areas at the VAJ and STJ were calculated; LV main chamber (non-LVOT) and LVOT volumes were calculated using multiple tetrahedra. End-diastole was defined as the peak of the electrocardiogram R-wave, and end-IVC when aortic cusp separation began. RESULTS: During IVC, blood within the left ventricle was redistributed to the LVOT: mean LVOT volume was increased (+0.2 +/- 0.1 ml, p = 0.009) as non-LVOT volume fell (-0.8 +/- 0.4 ml, p = 0.006). Concomitantly, the aortic root expanded as both VAJ and STJ areas increased (+0.23 +/- 0.12 cm2 (p = 0.005) and +0.25 +/- 0.14 cm2 (p = 0.007), respectively) prior to aortic cusp separation. CONCLUSION: Aortic root expansion prior to valve opening is closely related to intraventricular volume shifts into the LVOT during IVC. Such volume shifts may 'prime' the aortic valve for ejection. These findings expand our understanding of cardiac dynamics by showing that blood acts as a coupling link between various cardiac units. Preservation of these normal aortic root dynamics may enhance the efficacy and durability of aortic surgical interventions.

Cutting second-order chords does not prevent acute ischemic mitral regurgitation.

BACKGROUND: Cutting anterior mitral leaflet second-order chordae has been proposed for repair in ischemic mitral regurgitation (IMR). We examined the efficacy of such chordal cutting in preventing acute IMR. METHODS AND RESULTS: Six sheep underwent radiopaque marker placement (left ventricle, mitral annulus, papillary muscles [PMs], and leaflets). The largest second-order chord from each PM was encircled with exteriorized wire snares. Three-dimensional marker coordinates were obtained with biplane videofluoroscopy before and during acute ischemia (80 seconds of mid-circumflex occlusion). Color Doppler transesophageal echocardiography was used to grade MR on a 0 to 4+ scale. Data were acquired immediately before and after dividing second-order chordae. Slope of the end-diastolic volume-stroke work relationship (PRSW) was calculated to assess systolic function. Chordal cutting increased anterior leaflet inflection angle (155+/-12 versus 162+/-9 degrees; P=0.03), resulting in a flatter leaflet, but did not increase effective leaflet length (1.97+/-0.24 versus 2.08+/-0.23 cm; P=0.15); PRSW decreased (63+/-15 versus 56+/-12 mm Hg; P=0.008). Both before and after chordal cutting, ischemia caused: Septal-lateral annular dilation (P=0.005), posterior PM displacement away from the mid-septal annulus (P=0.06), increased leaflet tenting area (P=0.001), and increased leaflet tenting volume (P=0.002). Before chordal cutting, MR increased significantly during ischemia (0.5+/-0.3 versus 1.7+/-0.4; P<0.001), and IMR increased similarly even after the second-order chords were cut (0.7+/-0.4 versus 1.9+/-0.9; P<0.001). CONCLUSIONS: Cutting second-order chordae resulted in LV systolic dysfunction and neither prevented nor decreased the severity of acute IMR, septal-lateral annular dilation, leaflet tenting area, or leaflet tenting volume.

Importance of mitral valve second-order chordae for left ventricular geometry, wall thickening mechanics, and global systolic function.

BACKGROUND: Mitral valvular-ventricular continuity is important for left ventricular (LV) systolic function, but the specific contributions of the anterior leaflet second-order "strut" chordae are unknown. METHODS AND RESULTS: Eight sheep had radiopaque markers implanted to silhouette the LV, annulus, and papillary muscles (PMs); 3 transmural bead columns were inserted into the mid-lateral wall between the PMs. The strut chordae were encircled with exteriorized wire snares. Three-dimensional marker images and hemodynamic data were acquired before and after chordal cutting. Preload recruitable stroke work (PRSW) and end-systolic elastance (E(es)) were calculated to assess global LV systolic function (n=7). Transmural strains were measured from bead displacements (n=4). Chordal cutting caused global LV dysfunction: E(es) (1.48+/-1.12 versus 0.98+/-1.30 mm Hg/mL, P=0.04) and PRSW (69+/-16 versus 60+/-15 mm Hg, P=0.03) decreased. Although heart rate and time from ED to ES were unchanged, time of mid-ejection was delayed (125+/-18 versus 136+/-19 ms, P=0.01). Globally, the LV apex and posterior PM tip were displaced away from the fibrous annulus and LV base-apex length increased at end-diastole and end-systole (all +1 mm, P<0.05). Locally, subendocardial end-diastolic strains occurred: Longitudinal strain (E22) 0.030+/-0.013 and radial thickening (E33) 0.081+/-0.041 (both P<0.05 versus zero). Subendocardial systolic shear strains were also perturbed: Circumferential-longitudinal "micro-torsion" (E12) (0.099+/-0.035 versus 0.075+/-0.025) and circumferential radial shear (E13) (0.084+/-0.023 versus 0.039+/-0.008, both P<0.05). CONCLUSIONS: Cutting second-order chords altered LV geometry, remodeled the myocardium between the PMs, perturbed local systolic strain patterns affecting micro-torsion and wall-thickening, and caused global systolic dysfunction, demonstrating the importance of these chordae for LV structure and function.

Alterations in transmural strains adjacent to ischemic myocardium during acute midcircumflex occlusion.

OBJECTIVE: Helically oriented left ventricular fibers assemble into transmural sheets, which are important for wall-thickening mechanics: 15% fiber shortening results in 40% cross-fiber left ventricular wall thickening and a 60% ejection fraction through sheet extension, thickening, and shear. Normal cardiac microstructure and strains are optimized; deviations could result in apoptosis and deleterious matrix remodeling, which degenerates into global cardiomyopathy. We studied alterations in transmural strains adjacent to ischemic myocardium during acute midcircumflex occlusion. METHODS: Nine sheep had radiopaque markers implanted to measure left ventricular systolic fractional area shortening; 3 transmural bead columns were inserted into the midlateral wall for strain analysis. Three-dimensional marker coordinates were obtained with biplane videofluoroscopy before and during 70 seconds of ischemia. Systolic strains were quantified along circumferential, longitudinal, and radial axes (n = 9) and were transformed into fiber-sheet coordinates by using quantitative microstructural measurements (n = 5). RESULTS: A functional border was defined in the midlateral left ventricle; ischemia decreased posterolateral fractional area shortening, and anterolateral fractional area shortening increased. In this demarcation junction, subepicardial end-systolic radial wall thickening decreased (0.16 +/- 0.08 vs 0.11 +/- 0.06) and sheet-normal shear was abolished (0.08 +/- 0.04 vs -0.01 +/- 0.03). Longitudinal shortening decreased in the subepicardium and midwall (-0.05 +/- 0.04 vs +/- -0.01 +/- 0.06), but circumferential-radial shear increased at these depths (0.04 +/- 0.04 vs 0.11 +/- 0.05). Subendocardial fiber stretch occurred during early systole (-0.01 +/- 0.03 vs 0.02 +/- 0.03), and end-systolic fiber-sheet shear increased (0.07 +/- 0.01 vs 0.11 +/- 0.04, all P < .05). CONCLUSIONS: Increased circumferential-radial shear and altered fiber-sheet strains reflect mechanical interactions between ischemic and nonischemic myocardium, which might be important in triggering remodeling processes that evolve into global ischemic cardiomyopathy.