Left atrial and ventricular systolic and diastolic myocardial mechanics in patients with end-stage renal disease.

BACKGROUND: Diastolic cardiac dysfunction is an important complication of end-stage renal disease (ESRD), but quantification remains a challenge. Given that diastolic dysfunction is reflected in both left atrial (LA) and ventricular (LV) function, we aimed to identify abnormalities in LV and LA volume and function using measures of myocardial mechanics. METHODS: We retrospectively studied 53 incident ESRD patients (46±16 y/o 44% male) and compared them to 85 normal controls. LA phasic volumes and functional parameters were obtained from the apical 4CH view. Global ventricular peak longitudinal and circumferential strain, strain rate (GLS, GL-SR, CS), and rotation were obtained from apical and short-axis views. LA and LV measurements were taken off line using dedicated software (eSie VVI). RESULTS: ESRD patients had abnormal systolic function with lower LV ejection fraction and peak endocardial strain parameters (mean: GLS -16.6% vs -19.9%, GL-SR -0.91 vs -1.04, and CS -25.6% vs 27.9%, P≤.01 for all). Traditional Doppler parameters remained similar between groups, while diastolic mechanics were abnormal in ESRD. Reduced LV-derived diastolic parameters, fractional early reverse rotation, a marker of ventricular relaxation (P<.006), and ratio of early diastolic SR to systolic SR (P<.04) denote significant diastolic dysfunction. Increased LA volumes (P<.001), decreased LA reservoir (P<.001), conduit (P<.0004), and contractile (P<.02) function reflect diastolic dysfunction. CONCLUSION: Myocardial strain measurements quantitated the abnormalities in both LV diastolic and LA function associated with the uremic state. The distinct abnormal diastolic parameters were suggestive of abnormal relaxation and increased filling pressures. Early and accurate assessment of diastolic function may help tailor patient management ESRD.

Impact of pericardial adhesions on diastolic function as assessed by vortex formation time, a parameter of transmitral flow efficiency.

BACKGROUND: Pericardial adhesions are a pathophysiological marker of constrictive pericarditis (CP), which impairs cardiac filling by limiting the total cardiac volume compliance and diastolic filling function. We studied diastolic transmitral flow efficiency as a new parameter of filling function in a pericardial adhesion animal model. We hypothesized that vortex formation time (VFT), an index of optimal efficient diastolic transmitral flow, is altered by patchy pericardial-epicardial adhesions. METHODS: In 8 open-chest pigs, the heart was exposed while preserving the pericardium. We experimentally simulated early pericardial constriction and patchy adhesions by instilling instant glue into the pericardial space and using pericardial-epicardial stitches. We studied left ventricular (LV) function and characterized intraventricular blood flow with conventional and Doppler echocardiography at baseline and following the experimental intervention. RESULTS: Significant decreases in end-diastolic volume, ejection fraction, stroke volume, and late diastolic filling velocity reflected the effects of the pericardial adhesions. The mean VFT value decreased from 3.61 ± 0.47 to 2.26 ± 0.45 (P = 0.0002). Hemodynamic variables indicated the inhibiting effect of pericardial adhesion on both contraction (decrease in systolic blood pressure and +dP/dt decreased) and relaxation (decrease in the magnitude of -dP/dt and prolongation of Tau) function. CONCLUSION: Patchy pericardial adhesions not only negatively impact LV mechanical functioning but the decrease of VFT from normal to suboptimal value suggests impairment of transmitral flow efficiency.

Increase in the late diastolic filling force is associated with impaired transmitral flow efficiency in acute moderate elevation of left ventricular afterload.

OBJECTIVE: Analysis of intraventricular flow force and efficiency is a novel concept of quantitatively assessing left ventricular (LV) hemodynamic performance. We have parametrically characterized diastolic filling flow by early inflow force, late inflow force, and total inflow force and by vortex formation time (VFT), a fundamental parameter of fluid transport efficiency. The purpose of this study was to determine what changes in inflow forces characterize a decrease in diastolic blood transport efficiency in acute moderate elevation of LV afterload. METHODS: In 8 open-chested pigs, the flow force and VFT parameters were calculated from conventional and flow Doppler echocardiographic measurements at baseline and during a brief (3-minute) moderate elevation of afterload induced by increasing the systolic blood pressure to 130% of the baseline value. RESULTS: Systolic LV function decreased significantly during elevated afterload. Early inflow force did not significantly change, whereas late inflow force increased from 5,822.09 +/- 1,656.5 (mean +/- SD) to 13,948.25 +/- 9,773.96 dyne (P = .049), and total inflow force increased from 13,783.35 +/- 4,816.58 to 21,836.67 +/- 8,635.33 dyne (P = .031). Vortex formation time decreased from 4.09 +/- 0.29 to 2.79 +/- 1.1 (P = .0068), confirming suboptimal flow transport efficiency. CONCLUSIONS: Even a brief moderate increase of LV afterload causes a significant increase in late diastolic filling force and impairs transmitral flow efficiency.

Patients with Alzheimer disease have altered transmitral flow: echocardiographic analysis of the vortex formation time.

OBJECTIVE: There is considerable epidemiologic evidence that Alzheimer disease (AD) is linked to cardiovascular risk factors and associated with an increased risk of symptomatic left ventricular (LV) dysfunction. Formation of a vortex alongside a diastolic jet signifies an efficient blood transport mechanism. The vortex formation time (VFT) is an index of optimal conditions for vortex formation. We hypothesized that AD and its associated cardiovascular risk factors impair diastolic transmitral flow efficiency and, therefore, shift the VFT value out of its optimal range. METHODS: Echocardiographic studies were performed on 45 participants in total: 22 patients with AD diagnosed according to the American Psychiatric Association's criteria and 23 age-matched individuals as a control group with cognitive function within normal limits. RESULTS: The echocardiographic ratio of the early to atrial phases of the LV filling velocities was significantly lower in the AD group (mean +/- SD, 0.67 +/- 14) when compared with the control individuals (0.79 +/- 0.14; P = .003). The interventricular septum diastolic thickness, left ventricular posterior wall diastolic thickness, and right ventricular end-diastolic diameter were significantly higher in the AD group (P

The left ventricle responds to acute graded elevation of right ventricular afterload by augmentation of twist magnitude and untwist rate.

BACKGROUND: The right and left ventricles share the interventricular septum, which mechanically transmits pressure gradients. The aim of this study was to investigate how acute mild or moderate right ventricular (RV) afterload affects left ventricular (LV) function. METHODS: In 14 open-chest pigs (mean weight, 43 ± 4 kg) with preserved pericardium, acute mild (>35 and ≤50 mm Hg) and moderate (>50 and ≤60 mm Hg) RV pressure loading conditions were induced by constriction of the pulmonary artery. Hemodynamic parameters and LV twist and untwist were evaluated under each condition. RESULTS: From baseline to mild and moderate RV afterload, the mean RV systolic pressure increased from 31.0 ± 4.3 to 41.1 ± 2.7 and 52.7 ± 3.4 mm Hg (P < .001), while LV twist magnitudes increased from 15.4 ± 5.1° to 18.5 ± 3.1° and 19.8 ± 5.0° (P = .004), respectively. Absolute values of LV untwist rate increased from -116.9 ± 64.9°/sec to -160.0 ± 53.3°/sec and -169.1 ± 47.0°/sec, respectively (P = .001). After adjusting for all variables, only the ratio of the early and atrial components of mitral inflow and RV outflow tract acceleration time was significantly associated with the LV twist magnitude and LV untwist rate. CONCLUSIONS: In an acute setting, the left ventricle responds to suddenly elevated RV afterload and decreased RV stroke volume by promptly increasing its twist magnitude and untwist rate.

Revisiting the simplified bernoulli equation.

BACKGROUND: The assessment of the severity of aortic valve stenosis is done by either invasive catheterization or non-invasive Doppler Echocardiography in conjunction with the simplified Bernoulli equation. The catheter measurement is generally considered more accurate, but the procedure is also more likely to have dangerous complications. OBJECTIVE: The focus here is on examining computational fluid dynamics as an alternative method for analyzing the echo data and determining whether it can provide results similar to the catheter measurement. METHODS: An in vitro heart model with a rigid orifice is used as a first step in comparing echocardiographic data, which uses the simplified Bernoulli equation, catheterization, and echocardiographic data, which uses computational fluid dynamics (i.e., the Navier-Stokes equations). RESULTS: For a 0.93cm(2) orifice, the maximum pressure gradient predicted by either the simplified Bernoulli equation or computational fluid dynamics was not significantly different from the experimental catheter measurement (p > 0.01). For a smaller 0.52cm(2) orifice, there was a small but significant difference (p < 0.01) between the simplified Bernoulli equation and the computational fluid dynamics simulation, with the computational fluid dynamics simulation giving better agreement with experimental data for some turbulence models. CONCLUSION: For this simplified, in vitro system, the use of computational fluid dynamics provides an improvement over the simplified Bernoulli equation with the biggest improvement being seen at higher valvular stenosis levels.

Cardiac risk in patients aged >75 years with asymptomatic, severe aortic stenosis undergoing noncardiac surgery.

Severe aortic stenosis (AS) is a known predictor of cardiac risk during noncardiac surgery. However, for patients with asymptomatic AS, it is unclear whether aortic valve surgery should precede noncardiac surgery. We studied 30 patients with asymptomatic, severe AS with a mean age of 78 + or - 9 years, an aortic valve area of 0.77 + or - 0.16 cm(2), a mean gradient of 50.1 + or - 9.5 mm Hg, and a peak gradient of 84 + or - 22 mm Hg. They were compared to 60 age-matched (within 2 years) and gender-matched (ratio of 1:2) patients with mild-to-moderate AS (controls). The primary end point of the study was a composite of death, myocardial infarction, heart failure, ventricular arrhythmias before dismissal, and intraoperative hypotension requiring vasopressor administration. Most patients (>75%) and controls underwent intermediate-risk surgical procedures that were similar with respect to the nature of the surgery, type of anesthesia used, and preoperative risk assessment. Combined postoperative events were more common for the patients (n = 10; 33%) than for the controls (n = 14; 23%), but the difference was not statistically significant (p = 0.06). Intraoperative hypotension requiring vasopressor use was more likely for the patients (n = 9; 30%) than for the controls (n = 10; 17%; odds ratio 2.5; p = 0.11). The perioperative myocardial infarction rates were similar for both groups (3%; p = 0.74). No deaths, heart failure events, or ventricular arrhythmias occurred in the patients and 1 death and 1 ventricular arrhythmia episode occurred in the controls. In conclusion, intermediate-to-low-risk noncardiac surgery for patients with severe, asymptomatic AS can be performed relatively safely. Intraoperative hypotension was frequent and required prompt and aggressive treatment.

Right ventricular free wall circumferential strain reflects graded elevation in acute right ventricular afterload.

This study was designed to evaluate the concurrent changes in the right ventricular free wall (RVFW) movement in experimentally induced, acute mild, moderate, and severe right ventricle (RV) afterload conditions. In 14 open-chest pigs (weight 43 +/- 4 kg) with preserved pericardia, acute mild (>35 and <50 mmHg), moderate (> or =50 and < or =60 mmHg), and severe (>60 mmHg) increases in RV systolic pressure (RVSP) were induced by constriction of the pulmonary artery. At each step, longitudinal, radial, and circumferential strains and strain rates were measured in both the RVFW and the interventricular septum. The mean RVSPs were 31.0 +/- 4.3 mmHg at baseline and 41.1 +/- 2.7 mmHg during mild, 52.7 +/- 3.4 mmHg during moderate, and 61.7 +/- 1.6 mmHg during severe afterload conditions. The RVFW circumferential strains showed significant differences among baseline, mild, moderate, and severe afterload conditions (-10.5 +/- 3.9, -8.3 +/- 3.3, -5.4 +/- 2.7, and -7.5 +/- 5.3%, respectively, P = 0.008) and had significant linear correlation with RVSP (r = 0.636, P < 0.001) if the severe condition was excluded. Decrease of the RVFW circumferential strain magnitude is the most distinct response in acute mild and moderate RV afterload that could aid in detection of clinical conditions associated with acutely increasing RV afterload.

Extensive cardiac metastases secondary to uterine leiomyosarcoma.

Uterine leiomyosarcoma metastatic to multiple cardiac chambers occurs infrequently. Over the past 4 decades, there have been only 11 reported cases of cardiac metastasis secondary to uterine leiomyosarcoma. Metastatic cardiac tumors are commonly diagnosed postmortem, although it may be possible to diagnose them during life. The authors report a rare case of a 48-year-old woman with uterine leiomyosarcoma who was diagnosed with extensive cardiac metastases (in the left atrium, right and left ventricles, pulmonary artery, and pulmonary vein). Although extensive cardiac metastases are suggestive of imminent death, aggressive treatment resulted in survival for >1 year for this patient, which underscores the importance of treatment in select patients.

Quantification of left ventricular twisting mechanics by velocity vector imaging in an animal model of pericardial adhesions.

Diagnosis of constrictive pericarditis remains clinically challenging. Untwisting of the left ventricle (LV) is essential for normal LV diastolic function. Echocardiography is able to measure LV twisting mechanics. We designed an animal model of constrictive pericarditis to determine how pericardial-epicardial adhesions impair LV twisting mechanics. In eight open-chest pigs, the heart was exposed while preserving the pericardium. We simulated early constrictive pericarditis by pericardial constriction and patchy adhesions induced with instant glue and pericardial-epicardial stitches. Using Velocity Vector Imaging (VVI), LV magnitudes of twisting and untwisting were measured along with hemodynamic data at baseline and after the experimental intervention. Significant decreases in end-diastolic volume, ejection fraction, stroke volume, and late diastolic filling velocity reflected the effects of the pericardial adhesions. Magnitude of LV untwisting rate decreased from -80+/-23 degrees /s to -26+/-10 degrees /s (p=0.0009). LV twisting rate dropped from 78+/-20 degrees /s to 40+/-8 degrees /s (p=0.0039) and LV twist magnitude decreased from 9+/-2 degrees to 5+/-2 degrees (p=0.0081). Patchy pericardial adhesions are associated with reductions in LV untwisting rate and twisting magnitude, consistent with a negative impact of constrictive pericarditis on systolic and diastolic function. Impairments in LV twisting mechanics may have a diagnostic role in the detection of early stages of constrictive pericarditis.

Correlation of automated function imaging (AFI) to conventional strain analyses of regional and global right ventricular function.

BACKGROUND: Automated function imaging is a software tool available to facilitate the efficiency of workflow when analyzing left ventricular strain. In this study, automated function imaging was compared with a conventional approach for the analysis of right ventricular strain in normal and pressure-overloaded right ventricles. METHODS: Twelve pigs were subjected to graded acute right ventricular systolic pressure overload. Intraclass and interclass correlation coefficients (ICCs) with 95% confidence intervals were used for statistical evaluation, with grading based on the kappa statistic as follows: ICC >0.75 = excellent, 0.4 to 0.75 = good, and <0.40 = poor. RESULTS: Intraobserver and interobserver variability for both regional and global strains consistently ranged from good to excellent (ICC, 0.50-0.99), with good agreement between the conventional and automated methods. CONCLUSION: Automated function imaging correlates well with conventional strain analysis of the right ventricle. Automated function imaging is a practical tool for measuring regional and global longitudinal strain in both normal and pressure-overloaded right ventricles.

Impact of acute moderate elevation in left ventricular afterload on diastolic transmitral flow efficiency: analysis by vortex formation time.

BACKGROUND: The formation of a vortex alongside a diastolic jet signifies an efficient blood transport mechanism. Vortex formation time (VFT) is an index of the optimal conditions for vortex formation. It was hypothesized that left ventricular (LV) afterload impairs diastolic transmitral flow efficiency and therefore shifts the VFT out of its optimal range. METHODS: In 9 open-chest pigs, LV afterload was elevated by externally constricting the ascending aorta and increasing systolic blood pressure to 130% of baseline value for 3 minutes. RESULTS: Systolic LV function decreased, diastolic filling velocity increased only during the late (atrial) phase from 0.46 +/- 0.06 to 0.63 +/- 0.19 m/s (P = .0231), and end-diastolic LV volume and heart rate remained unchanged. VFT decreased from 4.09 +/- 0.27 to 2.78 +/- 1.03 (P = .0046). CONCLUSION: An acute, moderate elevation in LV afterload worsens conditions for diastolic vortex formation, suggesting impaired blood transport efficiency.