Michael Passick

Left Ventricular Filling Pressure Assessment Using Left Atrial Transit Time by Cardiac Magnetic Resonance Imaging

Background—Left atrial (LA) size and function reflect left ventricular (LV) hemodynamics. In the present study, we developed a novel method to determine LA circulation transit time (LATT) by MRI and demonstrated its close association with LV filling pressure. Methods and Results—All subjects were prospectively recruited and underwent contrast-enhanced MR dynamic imaging. Mean LATT was determined as the time for contrast to transit through the LA during the first pass. In an invasive study group undergoing clinically indicated cardiac catheterization (n=25), LATT normalized by R-R interval (nLATT) was closely associated with LV early diastolic pressure (r=0.850, P=0.001), LV end-diastolic pressure (r=0.910, P<0.001), and mean diastolic pressure (r=0.912, P<0.001). In a larger noninvasive group (n=56), nLATT was prolonged in patients with LV systolic dysfunction (n=47) (10.1±3.0 versus 6.6±0.7 cardiac cycles in normal control subjects, n=9; P<0.001). Using a linear regression equation derived from the invasive group, noninvasive subjects were divided into 3 subgroups by estimated LV end-diastolic pressure: ⩽10 mm Hg, 11 to 14 mm Hg, and ≥15 mm Hg. There were graded increases from low to high LV end-diastolic pressure subgroups in echocardiographic mitral medial E/e′ ratio: 9±5, 11±4, and 13±3 (P=0.023); in B-type natriuretic peptide (interquartile range): 44 (60) pg/mL, 87 (359) pg/mL, and 371 (926) pg/mL (P=0.002); and in N-terminal pro–B-type natriuretic peptide: 57 (163) pg/mL, 208 (990) pg/mL, and 931 (1726) pg/mL (P=0.002), demonstrating the ability of nLATT to assess hemodynamic status. Conclusions—nLATT by cardiac MR is a promising new parameter of LV filling pressure that may provide graded noninvasive hemodynamic assessment.

Effects of respiratory cycle and body position on quantitative pulmonary perfusion by MRI.

To evaluate the performance of lung perfusion imaging using two‐dimensional (2D) first pass perfusion MRI and a quantitation program based on model‐independent deconvolution algorithm.

Effects of Hemodynamics on Global and Regional Lung Perfusion A Quantitative Lung Perfusion Study by Magnetic Resonance Imaging

Background—Cardiac hemodynamics affect pulmonary vascular pressure and flow, but little is known of the effects of hemodynamics on lung perfusion at the tissue level. We sought to investigate the relationship between hemodynamic abnormalities in patients with left heart failure and global and regional lung perfusion using lung perfusion quantification by magnetic resonance imaging. Methods and Results—Lung perfusion was quantified in 10 normal subjects and 28 patients undergoing clinically indicated left and right heart catheterization and same day research cardiac magnetic resonance imaging. A total of 228 lung slices were evaluated. Global lung perfusion, determined as the average of 6 coronal lung slices through the anterior, mid, and posterior left and right lungs, was significantly lower in patients with reduced cardiac index (<2.5 L/min per m2): 94±30 mL/100 mL per minute versus 132±40 mL/100 mL per minute in those with preserved cardiac index (≥2.5 L/min per m2; P=0.003). The gravitational anterior to posterior perfusion gradient was inversely associated with left ventricular end-diastolic pressure (r=−0.728; P<0.001), resulting in a blunted perfusion gradient in patients with elevated left ventricular end-diastolic pressure, a finding largely attributed to the perfusion reduction in posterior lung regions. In a multivariate regression analysis adjusting for all hemodynamic variables, altered lung perfusion gradient was most closely associated with increased mean pulmonary arterial pressure (P=0.016). Conclusions—Increased left ventricular filling pressure and the resultant increase in pulmonary arterial pressure are associated with disruption of the normal gravitational lung perfusion gradient. Our findings underscore the complexity of heart-lung interaction in determining pulmonary hemodynamics in left heart failure.Background— Cardiac hemodynamics affect pulmonary vascular pressure and flow, but little is known of the effects of hemodynamics on lung perfusion at the tissue level. We sought to investigate the relationship between hemodynamic abnormalities in patients with left heart failure and global and regional lung perfusion using lung perfusion quantification by magnetic resonance imaging. Methods and Results— Lung perfusion was quantified in 10 normal subjects and 28 patients undergoing clinically indicated left and right heart catheterization and same day research cardiac magnetic resonance imaging. A total of 228 lung slices were evaluated. Global lung perfusion, determined as the average of 6 coronal lung slices through the anterior, mid, and posterior left and right lungs, was significantly lower in patients with reduced cardiac index (<2.5 L/min per m2): 94±30 mL/100 mL per minute versus 132±40 mL/100 mL per minute in those with preserved cardiac index (≥2.5 L/min per m2; P =0.003). The gravitational anterior to posterior perfusion gradient was inversely associated with left ventricular end-diastolic pressure ( r =−0.728; P <0.001), resulting in a blunted perfusion gradient in patients with elevated left ventricular end-diastolic pressure, a finding largely attributed to the perfusion reduction in posterior lung regions. In a multivariate regression analysis adjusting for all hemodynamic variables, altered lung perfusion gradient was most closely associated with increased mean pulmonary arterial pressure ( P =0.016). Conclusions— Increased left ventricular filling pressure and the resultant increase in pulmonary arterial pressure are associated with disruption of the normal gravitational lung perfusion gradient. Our findings underscore the complexity of heart-lung interaction in determining pulmonary hemodynamics in left heart failure.

Left atrial volume measurement with magnetic resonance imaging: a comparison of biplane, short axis and long axis methods

Left atrial (LA) dilation is an important index in cardiovascular disease. The CMR volumetric short axis method is the reference imaging standard but has limited ability to define the mitral valve plane accurately. The biplane method is simpler and frequently employed in clinical settings. We hypothesized that long axis two chamber (2ch) imaging might better define left atrial boundaries.

Relationship of prolonged global and regional central circulatory transit time with hemodynamics

Methods Forty nine subjects undergoing clinically indicated right and left heart cardiac catheterization were prospectively recruited to undergo MRI in a 1.5T scanner. First pass perfusion using steady state free precession saturation recovery sequence was performed with gadolinium infusion at 0.01 mmol/kg. Global TT was defined as the time between the peaks of time intensity curves between the right atrium and the ascending aorta. Segmental TT included TT between right atrium to pulmonary artery (right heart TT), pulmonary artery to left atrium (pulmonary TT), or left atrium to ascending aorta (left heart TT). All TTs were normalized to heart rate. Multivariate regression analysis was performed to delineate the relationship of hemodynamic parameters measured during cardiac catheterization to TT. Receiver operating characteristic (ROC) analyses were performed to assess ability of global and segmental TT to predict elevated LVEDP.

Effects of Hemodynamics on Global and Regional Lung Perfusion, A Quantitative Lung Perfusion Study by MRI

Background—Cardiac hemodynamics affect pulmonary vascular pressure and flow, but little is known of the effects of hemodynamics on lung perfusion at the tissue level. We sought to investigate the relationship between hemodynamic abnormalities in patients with left heart failure and global and regional lung perfusion using lung perfusion quantification by magnetic resonance imaging. Methods and Results—Lung perfusion was quantified in 10 normal subjects and 28 patients undergoing clinically indicated left and right heart catheterization and same day research cardiac magnetic resonance imaging. A total of 228 lung slices were evaluated. Global lung perfusion, determined as the average of 6 coronal lung slices through the anterior, mid, and posterior left and right lungs, was significantly lower in patients with reduced cardiac index (<2.5 L/min per m2): 94±30 mL/100 mL per minute versus 132±40 mL/100 mL per minute in those with preserved cardiac index (≥2.5 L/min per m2; P=0.003). The gravitational anterior to posterior perfusion gradient was inversely associated with left ventricular end-diastolic pressure (r=−0.728; P<0.001), resulting in a blunted perfusion gradient in patients with elevated left ventricular end-diastolic pressure, a finding largely attributed to the perfusion reduction in posterior lung regions. In a multivariate regression analysis adjusting for all hemodynamic variables, altered lung perfusion gradient was most closely associated with increased mean pulmonary arterial pressure (P=0.016). Conclusions—Increased left ventricular filling pressure and the resultant increase in pulmonary arterial pressure are associated with disruption of the normal gravitational lung perfusion gradient. Our findings underscore the complexity of heart-lung interaction in determining pulmonary hemodynamics in left heart failure.Background— Cardiac hemodynamics affect pulmonary vascular pressure and flow, but little is known of the effects of hemodynamics on lung perfusion at the tissue level. We sought to investigate the relationship between hemodynamic abnormalities in patients with left heart failure and global and regional lung perfusion using lung perfusion quantification by magnetic resonance imaging. Methods and Results— Lung perfusion was quantified in 10 normal subjects and 28 patients undergoing clinically indicated left and right heart catheterization and same day research cardiac magnetic resonance imaging. A total of 228 lung slices were evaluated. Global lung perfusion, determined as the average of 6 coronal lung slices through the anterior, mid, and posterior left and right lungs, was significantly lower in patients with reduced cardiac index (<2.5 L/min per m2): 94±30 mL/100 mL per minute versus 132±40 mL/100 mL per minute in those with preserved cardiac index (≥2.5 L/min per m2; P =0.003). The gravitational anterior to posterior perfusion gradient was inversely associated with left ventricular end-diastolic pressure ( r =−0.728; P <0.001), resulting in a blunted perfusion gradient in patients with elevated left ventricular end-diastolic pressure, a finding largely attributed to the perfusion reduction in posterior lung regions. In a multivariate regression analysis adjusting for all hemodynamic variables, altered lung perfusion gradient was most closely associated with increased mean pulmonary arterial pressure ( P =0.016). Conclusions— Increased left ventricular filling pressure and the resultant increase in pulmonary arterial pressure are associated with disruption of the normal gravitational lung perfusion gradient. Our findings underscore the complexity of heart-lung interaction in determining pulmonary hemodynamics in left heart failure.

1076 Effects of age and gender on right ventricular structure and function: a turning point at age fifty

Methods We studied 218 (99 male, 119 female) normotensive, non-obese (BMI < 28), non-diabetic volunteers aged 20– 90 (mean 54 ± 15) with normal 2-D echocardiograms on a 1.5 T Siemens Sonata scanner. TrueFISP cine imaging was used to obtain contiguous 8 mm short axis slices of the entire RV at end-expiration. Volumetric analysis was performed using Medis MASS. RV volume at end-diastole and end-systole and RV mass were determined and indexed to body surface area (EDVi, ESVi, RVMi) including papillary muscles in the cavity volume.

Prolonged central circulation transit time in patients with HFpEF and HFrEF by magnetic resonance imaging

Aims Prolonged central circulation transit time (TT) has long been associated with heart failure (HF) and left ventricular (LV) dysfunction. In this study, we assessed the central circulation TT using cardiovascular magnetic resonance imaging (CMR) in patients with HF of preserved ejection fraction (HFpEF) and of reduced EF (HFrEF) and investigated its relation to haemodynamics. Methods and results Fifty eight prospectively recruited volunteers underwent CMR. TT was taken as the time between the peaks of time-intensity curves from first pass perfusion images and normalized to cardiac cycle length intervals. Left ventricular ejection fraction was 55 ± 3%, 57 ± 7%, and 28 ± 10% in control (N = 10), HFpEF (N = 20), and HFrEF (N = 28), respectively (P < 0.001). Global central TT from right atrium to ascending aorta was significantly prolonged in patients with HFrEF [17 ± 5 cardiac cycles (cc)] and HFpEF (12 ± 3 cc) when compared to the normal controls (8 ± 1 cc) (P < 0.001). Regional TT was also prolonged in HF patients between right atrium and pulmonary artery (PA), PA and left atrium (LA), and LA and ascending aorta (all P-value < 0.001) with the longest delay seen between PA and LA. Among 48 HF patients, 28 underwent same day cardiac catheterization. Multivariate regression analysis suggested while reduced left and right ventricular EF were the strongest correlates for HFrEF increased pulmonary capillary wedge (PCWP) and reduced PA oxygen saturation were the strongest correlates for HFpEF. Conclusions Global and regional central TT can be assessed in the first pass perfusion imaging. Prolonged normalized global TT correlates with reduced EF in HFrEF and increased PCWP in HFpEF.

Comparisons of myocardial strain and strain rate in patients with heart failure with preserved and reduced ejection fraction using Feature Tracking of cine MR images

Methods All participants were prospectively recruited and underwent CMR in a 1.5 T scanner. LVEF 400 pg/ml. Patients with myocardial infarction were excluded. Myocardial circumferential strain (CST) and strain rate (CSR) was analyzed in mid LV of the short axis plane and the longitudinal strain (LST) and strain rate (LSR) in 4-chamber view of the SSFP cine images using feature tracking (CIM software, Auckland, New Zealand). LV end diastolic pressure (LVEDP) was estimated using normalized left atrial transition time from time-intensity curves of the first pass perfusion images.

Effects of breath-hold patterns, gadolinium concentrations and temporal resolutions on determination of mean left atrial circulation transit time by MR first pass perfusion

Background Normalized mean transit time in left atrium (nLATT) has potential to approximate left ventricular end diastolic pressure (LVEDP). In this study we prospectively evaluated the effects of gadolinium concentrations, breathhold patterns and temporal resolutions on determination of nLATT by MR first pass perfusion. Methods Twenty three patients were prospectively recruited to undergo MRI in a 1.5 T scanner. First pass perfusion imaging was performed using a saturation recovery steady state free precession sequence with ECG gating during breath-hold with Gadopentetate dimeglumine (Gd) injected at 0.01 mmol/kg. Imaging was repeated with freebreathing followed by breath-hold imaging using Gd at 0.025 mmol/kg separated with washout periods of 10 to 15 minutes. LATT was determined from the time intensity curves of the first pass using a custom program to assess time-signal integral and normalized by RR duration. nLATT was compared using paired t-test between images acquired in 3 settings. Additional 7 volunteers were recruited to undergo first pass perfusion with dynamic image acquired every 113 ms (TR) without ECG gating. To evaluate the effect of temporal resolution, LATT was assessed using simulated TR sampling dynamic signal intensity at multitudes of TR, respectively. Results