Evaluation of the Effects of an Extubation Protocol With Neostigmine on Duration of Mechanical Ventilation After Cardiac Surgery.

OBJECTIVES: Residual neuromuscular blockade is associated with increased postoperative pulmonary complications. This study aimed to evaluate the effect of an extubation protocol incorporating neuromuscular blockade reversal (NMBR) by train-of-four monitoring on "fast-track" cardiac surgery outcomes. DESIGN: A retrospective cohort study. SETTING: At a university hospital. PARTICIPANTS: Out of 1,843 cardiac surgery patients, from February 2, 2015, to March 31, 2017, 957 (52%) underwent cardiac surgery on or after February 29, 2016. INTERVENTIONS: An extubation protocol, comprised of weaning from mechanical ventilation and NMBR guidelines, was implemented on February 29, 2016. MEASUREMENTS AND MAIN RESULTS: The associations of baseline characteristics with the postoperative duration of mechanical ventilation (primary outcome) and respiratory and/or adverse complications (secondary outcomes) were evaluated using regression and interrupted- time series models. The implementation of an extubation protocol was associated with an 18% decrease in the duration of mechanical ventilation (incident rate ratio [IRR] 0.82, 95% CI 0.72-0.94; p < 0.01), statistically insignificant 26% increase in patients extubated ≤6 hours (odds ratio [OR] 1.26, 95% CI 0.97-1.65; p = 0.09), and 13% shorter intensive care unit length of stay (LOS) (IRR 0.87, 95% CI 0.79-0.97; p < 0.01). Patients undergoing isolated coronary artery bypass graft or isolated valve procedures, on or after February 29, 2016, had decreased extubation times (IRR 0.82, p < 0.01 and IRR 0.80, p = 0.02). The protocol did not have a statistically significant association with hospital LOS (IRR 0.98, p = 0.57) or readmission (OR 1.22, p = 0.33), and differences in the occurrence of pulmonary complications and adverse outcomes between the pre- and postprotocol groups were clinically insignificant. CONCLUSIONS: The application of an extubation protocol incorporating NMBR based on neuromuscular monitoring was associated with a decrease in postoperative duration of mechanical ventilation and facilitated more patients meeting the early extubation benchmark without an increased risk of respiratory complications or adverse outcomes.

Timing of Blood Transfusions and 30-Day Patient Outcomes After Coronary Artery Bypass Graft Surgery.

OBJECTIVE: Packed red blood cell transfusion during coronary artery bypass graft surgery is known to be associated with adverse outcomes. However, the association of the timing between transfusions in relation to discharge and 30-day postoperative outcomes has not been studied. The study authors investigated the impact of transfusion timing on 30-day surgical outcomes. DESIGN: A retrospective review. SETTING: At a single tertiary-care academic hospital. PARTICIPANTS: A total of 2,481 adult patients underwent primary coronary artery bypass graft surgery between January 2014 and December 2020. MEASUREMENTS AND MAIN RESULTS: The relationship between the timing of packed red blood cell transfusion (intraoperative, postoperative, or both) and 30-day postoperative outcome variables was calculated as an odds ratio. The influence of timing of transfusion on adjusted probability of postoperative complications was plotted against the lowest intraoperative hematocrit. The median age of the population was 67 years (60.0-74.0), body mass index was 28.5 (25.6-32.3) kg/m2, and 497 (20.0%) were female. A total of 1,588 (36%) patients received packed red blood cell transfusions; 182 (7.3%) received intraoperative transfusions, 489 (19.7%) received postoperative transfusions, and 222 (9.0%) received both (intraoperative and postoperative transfusions). Postoperative transfusion was associated with significantly higher odds of readmission (1.83 [1.32-2.54], p = 0.002) and heart failure (1.64 [1.2-2.23], p = 0.008) compared to patients with no transfusions; whereas intraoperative transfusions were not. CONCLUSION: The authors' data suggested that the postoperative timing of transfusion in patients undergoing coronary artery bypass graft surgery may be associated with an increased incidence of 30-day heart failure and readmission. Prospective research is needed to conclusively confirm these findings.

Echocardiographic Assessment of the Mitral Valve for Suitability of Repair: An Intraoperative Approach From a Mitral Center.

Intraoperative echocardiography of the mitral valve in the precardiopulmonary bypass period is an integral part of the surgical decision-making process for assessment of suitability for repair. Although there are comprehensive reviews in the literature regarding echocardiographic examination of the mitral valve, the authors present a practical stepwise algorithmic workflow to make objective recommendations. Advances in echocardiography allow for quantitative geometric analyses of the mitral valve, along with precise assessment of the valvular apparatus with three-dimensional echocardiography. In the precardiopulmonary bypass period, echocardiographers are required to diagnose and quantify valvular dysfunction, assess suitability for repair, assist in annuloplasty ring sizing, and determine the success or failure of the surgical procedure. In this manuscript the authors outline an algorithmic approach to intraoperative echocardiography examination using two-dimensional and three-dimensional modalities to objectively analyze mitral valve function and assist in surgical decision-making.

Three-Dimensional Printing of Patient-Specific Heart Valves: Separating Facts From Fiction and Myth From Reality.

The development of prosthetic heart valves by Dr. Charles Hufnagel in 1952 was a major clinical innovation; however, it was not an ideal solution. Mechanical prosthetic heart valves are rigid, immunogenic, require anticoagulation, do not grow with the patient, and have a finite life.1 An ideal prosthetic valve should overcome all these limitations. Considering the prevalence of valvular heart disorders, there is considerable interest in the creation of patient-specific heart valves. Following the introduction of three-dimensional (3D) printing in 1986 by Chuck Hill, rapid advances in multimodality 3D imaging and modeling have led to a generation of tangible replicas of patient-specific anatomy. The science of organogenesis has gained importance for a multitude of valid reasons: as an alternate source of organs, for realistic drug testing, as an alternative to animal testing, and for transplants that grow with the patient. What scientists imagined to be seemingly impossible in the past now seems just a step away from becoming a reality. However, due to the disruptive nature of this technology, often there are commercially-motivated claims of originality and overstatement of the scope and applicability of 3D printing. It often is difficult to separate fact from fiction and myth from reality. In this manuscript, the authors have reviewed the historic perspective, status of the basic techniques of organogenesis with specific reference to heart valves, and their potential.

Intraoperative Oxygen Concentration and Neurocognition after Cardiac Surgery.

BACKGROUND: Despite evidence suggesting detrimental effects of perioperative hyperoxia, hyperoxygenation remains commonplace in cardiac surgery. Hyperoxygenation may increase oxidative damage and neuronal injury leading to potential differences in postoperative neurocognition. Therefore, this study tested the primary hypothesis that intraoperative normoxia, as compared to hyperoxia, reduces postoperative cognitive dysfunction in older patients having cardiac surgery. METHODS: A randomized double-blind trial was conducted in patients aged 65 yr or older having coronary artery bypass graft surgery with cardiopulmonary bypass. A total of 100 patients were randomized to one of two intraoperative oxygen delivery strategies. Normoxic patients (n = 50) received a minimum fraction of inspired oxygen of 0.35 to maintain a Pao2 above 70 mmHg before and after cardiopulmonary bypass and between 100 and 150 mmHg during cardiopulmonary bypass. Hyperoxic patients (n = 50) received a fraction of inspired oxygen of 1.0 throughout surgery, irrespective of Pao2 levels. The primary outcome was neurocognitive function measured on postoperative day 2 using the Telephonic Montreal Cognitive Assessment. Secondary outcomes included neurocognitive function at 1, 3, and 6 months, as well as postoperative delirium, mortality, and durations of mechanical ventilation, intensive care unit stay, and hospital stay. RESULTS: The median age was 71 yr (interquartile range, 68 to 75), and the median baseline neurocognitive score was 17 (16 to 19). The median intraoperative Pao2 was 309 (285 to 352) mmHg in the hyperoxia group and 153 (133 to 168) mmHg in the normoxia group (P < 0.001). The median Telephonic Montreal Cognitive Assessment score on postoperative day 2 was 18 (16 to 20) in the hyperoxia group and 18 (14 to 20) in the normoxia group (P = 0.42). Neurocognitive function at 1, 3, and 6 months, as well as secondary outcomes, were not statistically different between groups. CONCLUSIONS: In this randomized controlled trial, intraoperative normoxia did not reduce postoperative cognitive dysfunction when compared to intraoperative hyperoxia in older patients having cardiac surgery. Although the optimal intraoperative oxygenation strategy remains uncertain, the results indicate that intraoperative hyperoxia does not worsen postoperative cognition after cardiac surgery.

Development of an Instrument for Preoperative Prediction of Adverse Discharge in Patients Scheduled for Cardiac Surgery.

OBJECTIVE: Inability of home discharge occurs in nearly a third of patients undergoing cardiac surgery and is associated with increased mortality. The authors aimed to evaluate the incidence and risk factors for adverse discharge disposition (ADD) after cardiac surgery and develop a prediction tool for preoperative risk assessment. DESIGN: This retrospective cohort study included adult patients undergoing cardiac surgery between 2010 and 2018. The primary outcome was ADD, defined as in-hospital mortality, discharge to a skilled nursing facility, or transfer to a long-term care hospital. The authors created a prediction tool using stepwise backward logistic regression and used 5-fold and leave-one-out cross-validation. SETTING: University hospital network. PARTICIPANTS: Adult patients living at home prior to surgery, who underwent coronary artery bypass grafting and/or valve procedures at the authors' institution. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A total of 3,760 patients were included in the final study cohort. The observed rate of ADD was 33.3%. The prediction model showed good discrimination and accuracy, with C-statistic of 0.78 (95% confidence interval [CI] 0.76-0.79) and unmodified Brier score of 0.177 (reliability 0.001). The final model comprised 14 predictors. Patients who experienced ADD were more likely to be older, of female sex, to have had higher length of hospital stay prior to surgery, and to have undergone emergency surgery. CONCLUSIONS: The authors present an instrument for prediction of loss of the ability to live independently in patients undergoing cardiac surgery. The authors' score may be useful in identifying high-risk patients such that earlier coordination of care can be initiated in this vulnerable patient population.

Cardiac surgeons' concerns, perceptions, and responses during the COVID-19 pandemic.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has had an unprecedented impact on health care and cardiac surgery. We report cardiac surgeons' concerns, perceptions, and responses during the COVID-19 pandemic. METHODS: A detailed survey was sent to recruit participating adult cardiac surgery centers in North America. Data regarding cardiac surgeons' perceptions and changes in practice were analyzed. RESULTS: Our study comprises 67 institutions with diverse geographic distribution across North America. Nurses were most likely to be redeployed (88%), followed by advanced care practitioners (69%), trainees (28%), and surgeons (25%). Examining surgeon concerns in regard to COVID-19, they were most worried with exposing their family to COVID-19 (81%), followed by contracting COVID-19 (68%), running out of personal protective equipment (PPE) (28%), and hospital resources (28%). In terms of PPE conservation strategies among users of N95 respirators, nearly half were recycling via decontamination with ultraviolet light (49%), followed by sterilization with heat (13%) and at home or with other modalities (13%). Reuse of N95 respirators for 1 day (22%), 1 week (21%) or 1 month (6%) was reported. There were differences in adoption of methods to conserve N95 respirators based on institutional pandemic phase and COVID-19 burden, with higher COVID-19 burden institutions more likely to resort to PPE conservation strategies. CONCLUSIONS: The present study demonstrates the impact of COVID-19 on North American cardiac surgeons. Our study should stimulate further discussions to identify optimal solutions to improve workforce preparedness for subsequent surges, as well as facilitate the navigation of future healthcare crises.

Comparative utility of frailty to a general prognostic score in identifying patients at risk for poor outcomes after aortic valve replacement.

BACKGROUND: Current guidelines recommend considering life expectancy before aortic valve replacement (AVR). We compared the performance of a general mortality index, the Lee index, to a frailty index. METHODS: We conducted a prospective cohort study of 246 older adults undergoing surgical (SAVR) or transcatheter aortic valve replacement (TAVR) at a single academic medical center. We compared performance of the Lee index to a deficit accumulation frailty index (FI). Logistic regression was used to assess the association of Lee index or FI with poor outcome, defined as death or functional decline with severe symptoms at 12 months. Discrimination was assessed using C-statistics. RESULTS: In the overall cohort, 44 experienced poor outcome (31 deaths, 13 functional decline with severe symptoms). The risk of poor outcome by Lee index quartiles was 6.8% (reference), 17.9% (odds ratio [OR], 3.0; 95% confidence interval, [0.9-10.2]), 20.0% (OR 3.4; [1.0-11.4]), and 34.0% (OR 7.1; [2.2-22.6]) (p-for-trend = 0.001). Risk of poor outcome by FI quartiles was 3.6% (reference), 10.3% (OR 3.1; [0.6-15.8]), 25.0% (OR 8.8; [1.9-41.0]), and 37.3% (OR 15.8; [3.5-71.1]) (p-for-trend< 0.001). The Lee index predicted the risk of poor outcome in the SAVR cohort Lee index (quartiles 1-4: 2.1, 4.0, 15.4, and 20.0%; p-for-trend = 0.04), but not in the TAVR cohort (quartiles 1-4: 27.3, 29.0, 21.3, 35.4%; p-for-trend = 0.42). In contrast, the FI did not predict the risk of poor outcome well in the SAVR cohort (quartiles 1-4: 2.3, 4.4, 15.8, and 0%; p-for-trend = 0.24), however in the TAVR cohort (quartiles 1-4: 9.1, 14.3, 29.7, and 40.7%; p-for-trend = 0.004). Compared to the Lee index, an FI demonstrated higher C-statistics in the overall (Lee index versus FI: 0.680 versus 0.735; p = 0.03) and TAVR (0.560 versus 0.644; p = 0.03) cohorts, but not SAVR cohort (0.724 versus 0.766; p = 0.09). CONCLUSIONS: While a general mortality index Lee index predicted death or functional decline with severe symptoms at 12 months well among SAVR patients, the FI derived from a multi-domain geriatric assessment better informs risk-stratification for high-risk TAVR patients.

Artificial Intelligence for Dynamic Echocardiographic Tricuspid Valve Analysis: A New Tool in Echocardiography.

There has been a resurgence of interest in the structure and function of the tricuspid valve (TV) with the established prognostic impact of functional tricuspid regurgitation. Current 3-dimensional transesophageal echocardiography prototype software is limited to exploration of the mitral and aortic valves exclusively. Thus, newer analytical software is required for dynamic geometric analysis of the TV morphology for remodeling. This article presents a preliminary experience with novel artificial intelligence-based semiautomated software for TV analysis. The software offers high correlation to surgical inspection by its ability to analyze morphology and dynamics of the valve throughout the cardiac cycle. In addition, it allows higher reproducibility of data analysis and reduces interobserver variability with minimal need for manual intervention. Integration of interactivity through preprocedural placement of specific devices of different sizes and shapes in the mitral and aortic positions facilitates prognostic evaluation of surgical and interventional procedures.

Immediate Preoperative Transthoracic Echocardiography for the Prediction of Postoperative Atrial Fibrillation in High-Risk Cardiac Surgery.

OBJECTIVE: The present study aimed to validate the utility of bedside cardiac ultrasound to identify patients for the risk of postoperative atrial fibrillation (POAF). DESIGN: A prospective cohort study of consecutive patients. SETTING: Single-center tertiary referral center. PARTICIPANTS: After Institutional Review Board consent, 169 patients undergoing elective cardiac surgery were enrolled in the study. INTERVENTIONS: A preoperative transthoracic echocardiographic interrogation assessing diastolic function was performed. Measurements were assessed offline with experienced echocardiographers blinded to clinical outcomes. MEASUREMENTS AND MAIN RESULTS: The primary outcome was POAF during the first 72 hours after surgery. A total of 169 patients completed the study, 44 of whom (26.0%) developed POAF, and 39 (25.2%) had diastolic dysfunction. Patients with POAF had a higher rate of postoperative heart failure, reintubation within 24 hours of surgery, and length of stay (p = 0.002, 0.01, and 0.0006, respectively). Predictors significant for POAF included increasing age, left atrial volume indexed to body surface area (LAVI), and diastolic dysfunction (p = 0.02, 0.0001, and 0.001, respectively). Multivariate spline regressions demonstrated a nonlinear correlation between increasing LAVI and risk of POAF. CONCLUSION: Left atrial volume can be assessed efficiently preoperatively to provide superior risk stratification over clinical factors and diastolic parameters alone for the prediction of POAF. Furthermore, the present study demonstrated that the cutoffs of chamber quantification currently used do not appropriately capture the increased risk of POAF. Thus, LAVI provides a simple measure to identify patients who are in need of targeted prophylaxis for POAF.

Complexity of preoperative blood pressure dynamics: possible utility in cardiac surgical risk assessment.

Complexity measures are intended to assess the cardiovascular system's capacity to respond to stressors. We sought to determine if decreased BP complexity is associated with increased estimated risk as obtained from two standard instruments: the Society of Thoracic Surgeons' (STS) Risk of Mortality and Morbidity Index and the European System for Cardiac Operative Risk Evaluation Score (EuroSCORE II). In this observational cohort study, preoperative systolic, diastolic, mean (MAP) and pulse pressure (PP) time series were derived in 147 patients undergoing cardiac surgery. The complexity of the fluctuations of these four variables was quantified using multiscale entropy (MSE) analysis. In addition, the traditional time series measures, mean and standard deviation (SD) were also computed. The relationships between time series measures and the risk indices (after logarithmic transformation) were then assessed using nonparametric (Spearman correlation, rs) and linear regression methods. A one standard deviation change in the complexity of systolic, diastolic and MAP time series was negatively associated (p < 0.05) with the STS and EuroSCORE indices in both unadjusted (21-34%) and models adjusted for age, gender and SD of the BP time series (15-31%). The mean and SD of BP time series were not significantly associated with the risk index except for a positive association with the SD of the diastolic BP. Lower preoperative BP complexity was associated with a higher estimated risk of adverse cardiovascular outcomes and may provide a novel approach to assessing cardiovascular risk. Future studies are needed to determine whether dynamical risk indices can improve current risk prediction tools.

Dynamic Three-Dimensional Geometry of the Aortic Valve Apparatus-A Feasibility Study.

OBJECTIVE: To provide (1) an overview of the aortic valve (AV) apparatus anatomy and nomenclature, and (2) data regarding the normal AV apparatus geometry and dynamism during the cardiac cycle obtained from three-dimensional transesophageal echocardiography (3D TEE). DESIGN: Retrospective feasibility study. SETTING: A single-center university teaching hospital. PARTICIPANTS: The study was performed on data of 10 patients with a nonregurgitant, nonstenotic aortic valve undergoing cardiac surgery. INTERVENTIONS: Intraoperative 3D TEE was performed on all the participants using the Siemens ACUSON SC2000 ultrasound system and Z6Ms transducer (Siemens Medical Systems, Mountainview, CA). MEASUREMENTS AND MAIN RESULTS: Dynamic offline analyses were performed with Siemens eSie valve analytical software in a semiautomated fashion. Forty-five parameters were exported of which 13 were selected and analyzed. The cardiac cycle was divided into 4 quartiles to account for frame-rate variations. The annulus, sinus of Valsalva (SoV) and sinotubular junction (STJ) areas, diameter, perimeter and height, aortic leaflet height, leaflet coaptation height, and aortic valve-mitral valve angle changed significantly during the cardiac cycle (p < 0.001). STJ expanded more than both the annulus and the SoV (p < 0.001). The maximum aortic valve leaflet height change was greater in the left and right versus noncoronary leaflet (p < 0.001). CONCLUSIONS: The semiautomated AV apparatus dynamic assessment using eSie valve software is a clinically feasible technique and can be performed readily in the operating room. It has the potential to significantly impact intraoperative decision-making in cases suitable for AV repair. The AV apparatus is a dynamic structure and demonstrates significant changes during the cardiac cycle.

Changes in Tricuspid Annular Geometry in Patients with Functional Tricuspid Regurgitation.

OBJECTIVE: To determine whether the indices of tricuspid annular dynamics that signify irreversible tricuspid valvular remodeling can improve surgical decision making by helping to better identify patients with functional tricuspid regurgitation who could benefit from annuloplasty. DESIGN: Retrospective analysis study. SETTING: Tertiary hospital. PARTICIPANTS: A total number of 55 patients were selected, 18 with functional tricuspid valve (TV) regurgitation and 37 normal nonregurgitant TVs. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: When comparing the basal, mid, and longitudinal diameters of the right ventricle between the nonregurgitant valve (NTR) group and the functional tricuspid regurgitation (FTR) group, tricuspid annulus was more dilated (p < 0.001, p = 0.001, and p = 0.006, respectively) and less nonplanar (p < 0.001) in the FTR group. At end-systole (ES), the posterolateral-anteroseptal axis was significantly greater in the FTR group than in the NTR group (mean difference = 7.15 mm; p < 0.001). The right ventricle in the FTR group was also significantly dilated with greater leaflet restriction (p = 0.015). CONCLUSIONS: As compared to NTR TVs, FTR is associated with identifiable indices of tricuspid annular structural changes that are indicative of irreversible remodeling.

Heterogeneity in the Structure of the Left Ventricular Outflow Tract: A 3-Dimensional Transesophageal Echocardiographic Study.

BACKGROUND: The left ventricular outflow tract (LVOT) is a composite of adjoining structures; therefore, a circular or elliptical shape at one point may not represent its entire structure. The purpose of this study was to evaluate the presence of heterogeneity in the LVOT. METHODS: Patients with normal valvular and ventricular function undergoing elective coronary revascularization surgery were included in the study. Intraoperative R-wave gated 3-dimensional (3D) transesophageal echocardiographic imaging of the LVOT was performed at end-systole, with the midesophageal long axis as the reference view. Acquired data were analyzed with the Philips Q-Lab software with multiplanar reformatting in the sagittal (minor axis), transverse (major axis), and coronal (cross-sectional area by planimetry) views of the LVOT. These measurements were made on the left ventricular side or proximal LVOT, aortic side, or distal LVOT and mid-LVOT. RESULTS: Fifty patients were included in the study. The LVOT minor (sagittal) axis dimension did not differ across the mid-LVOT, proximal LVOT, and distal LVOT (P = .11). The major axis diameter of LVOT differed among the 3 regions of the LVOT (P < .001). A difference in major axis diameter was observed between the proximal and the distal LVOT (median difference of 0.39 cm; Bonferroni-adjusted 95% confidence interval [CI] of the difference = 0.31-0.48 cm; Bonferroni-adjusted P < .001). Planimetry of the LVOT area differed significantly (P < .001) between the regions analyzed, and we found a difference between the distal and the proximal LVOT (median difference = 0.65 cm, Bonferroni-adjusted 95% CI of the difference = 0.44-0.88 cm, Bonferroni-adjusted P < .001). The LVOT area calculated from minor axis diameter differed significantly from the area obtained by planimetry (P < .001). CONCLUSIONS: There was heterogeneity in the major axis diameter and cross-sectional area for the different regions of the LVOT. The distal LVOT (aortic side) was more circular, whereas the proximal LVOT (left ventricular side) was more elliptical in shape. This change in shape from circular to elliptical was accounted for by a difference in the major axis diameter from proximal to distal LVOT and a relatively similar minor axis diameter. Although the clinical significance of this finding is unknown, the assumption of a uniform structure of LVOT is incorrect. Three-dimensional imaging may be useful for assessing the LVOT shape and size at a specific region of interest.

Dynamism of the mitral annulus: a spatial and temporal analysis.

OBJECTIVE: In this study, the authors sought to investigate the extent and timing of changes in mitral annular area during the cardiac cycle. Particularly, the authors assessed whether these changes were limited to the posterior part of the annulus or were more global in nature. DESIGN: Prospective, observational study SETTING: Tertiary care university hospital PARTICIPANTS: Twenty three patients undergoing non-valvular cardiac surgery and 3 patients undergoing vascular procedures. INTERVENTIONS: Intraoperative 3-dimensional transesophageal echocardiographic data obtained from patients with normal mitral valves undergoing non-valvular cardiac surgery were analyzed geometrically. Annular areas and diameters were measured during various stages of the cardiac cycle. Intertrigonal distance also was measured using 3D data. MEASUREMENTS AND MAIN RESULTS: Both anterior and posterior portions of the mitral annulus demonstrated dynamism throughout the cardiac cycle. The expansion phase ranged from mid-systole to early-diastole, whereas mid-diastole to early-systole was characterized by an annular contraction phase. Area changes were contributed equally by anterior and posterior parts of the annulus. Annular dimensions increased in accordance with mitral annular area (p<0.05). Echocardiographically-identified intertrigonal distance showed the least delta change. CONCLUSIONS: Both the anterior and posterior parts of the annulus contribute to changes in mitral annular area, which undergoes discrete expansion and contraction phases that extend into both systole and diastole. Compared to other annular dimensions, the echocardiographically-identified intertrigonal distance does not change significantly during the cardiac cycle.