Sharon L. Mulvagh

Estimation of left ventricular end-diastolic pressure from Doppler transmitral flow velocity in cardiac patients independent of systolic performance

In patients with heart disease, changes in left ventricular filling pressures produce alterations in the Doppler transmitral flow velocity and isovolumetric relaxation time. This investigation explored the hypothesis that combining isovolumetric relaxation time with measurements derived from the transmitral flow velocity can be used to estimate left ventricular end-diastolic pressure. Simultaneous Doppler and left ventricular pressure recordings were obtained in 33 patients (24 men with a mean age of 58 +/- 11 years) and an ejection fraction ranging from 15% to 74% (mean 55 +/- 15%). The following Doppler measurements correlated significantly with left ventricular end-diastolic pressure (range 4 to 36 mm Hg): isovolumetric relaxation time (IVRT; r = -0.73), atrial filling fraction (AFF; r = -0.66), deceleration time (DT; r = -0.59), ratio of early transmitral flow velocity to atrial flow velocity (E/A ratio; r = -0.53) and time from termination of mitral flow to the electrocardiographic R wave (MAR; r = 0.37). Combining these measurements into a multilinear regression equation provided a more accurate estimate of end-diastolic pressure (LVEDP; r = 0.80; SEE = 7.4). The equation LVEDP = 46 -0.22 IVRT -0.10 AFF -0.03 DT -(2 divided by E/A) + 0.05 MAR was tested prospectively in 26 additional patients (mean age 55 +/- 11 years; ejection fraction 41 +/- 23%) with simultaneous Doppler and hemodynamic recordings but with the two measurements made independently, in blinded fashion, by additional observers. Estimated and measured end-diastolic pressures correlated well with each other (r = 0.86).(ABSTRACT TRUNCATED AT 250 WORDS)

Nuclear magnetic resonance imaging of the pulmonary arteries, subpulmonary region, and aorticopulmonary shunts: A comparative study with two-dimensional echocardiography and angiography

Twelve patients more than 8 years of age with complex congenital heart disease were evaluated prospectively with nuclear magnetic resonance (NMR) imaging and with echocardiographic and angiographic imaging techniques. The subpulmonary region, main pulmonary artery, right and left pulmonary arteries, and aorticopulmonary shunts were clearly visualized by means of NMR imaging in all patients. Angiography defined the subpulmonary region and main pulmonary artery in all patients, the right and left pulmonary arteries along their length in 11 of 12 patients, and aorticopulmonary shunts in seven of eight patients. Except for the right pulmonary artery, echocardiography defined the remaining structures in less than or equal to 50% of patients. Measurement of the pulmonary artery diameters on NMR images correlated well with the angiographic measurements of both the left (r = 0.96) and right (r = 0.94) pulmonary arteries. These results suggest that NMR imaging may be the preferable noninvasive imaging technique for defining the anatomy of the subpulmonary region, main and left pulmonary arteries, and aorticopulmonary shunts in older patients with congenital cardiovascular disease and that it compares well with the angiographic standard.

Usefulness of nuclear magnetic resonance imaging for evaluation of pericardial effusions, and comparison with two-dimensional echocardiography.

Nuclear magnetic resonance (NMR) imaging clearly delineates cardiovascular structures without interference from overlying bone and lung tissue. The techniques of NMR imaging and echocardiography were compared in 26 patients with pericardial effusions, 10 of whom had associated pleural effusions. In those patients with fluid detected by both techniques, estimated size of the effusion tended to be somewhat larger by NMR. NMR imaging detected several small pericardial effusions that were not visualized by echocardiography. Both techniques demonstrated loculation well, although NMR imaging was better for detecting fluid located superiorly at the aortic pericardial reflection site, medially at the border of the right atrium and posteriorly at the left ventricular apex. In the 14 patients with documented exudative effusions (10 pericardial, 4 pleural) NMR signals of varying intensity were present in the effusion. One patient had a documented transudative effusion and no NMR signal was observed in the fluid. NMR imaging clearly distinguished pericardial from pleural effusions. NMR imaging is indicated when a suspected pericardial effusions is not detected by echocardiography or when specific localization or fluid characterization is desired.

Nuclear magnetic resonance imaging of acute myocardial infarction within 24 hours of chest pain onset.

The present study was intended to establish the feasibility, safety and usefulness of conventional spin-echo nuclear magnetic resonance (NMR) imaging for the detection of acute myocardial infarction within 24 hours of the onset of chest pain. Monitoring facilities were established in the NMR imaging suite that provided the same level of reliability and safety found in a standard coronary care unit. An imaging protocol was developed that allowed the acquisition of a complete study in 30 minutes while providing useful information about mechanical function and myocardial tissue contrast. Eighteen postthrombolysis patients were imaged within 21 +/- 2 hours of chest pain onset. No patient developed recurrent chest pain or arrhythmias in the NMR imaging suite. Relatively T2-weighted spin-echo images (echo time = 60 ms; repetition time = heart rate) provided interpretable images in 16 patients. Fourteen normal subjects were imaged for comparison. Thirteen of 16 patients had an increase in signal intensity in the region of the infarction. Regional wall thickening was assessed using a floating endocardial centroid technique. Wall motion abnormalities detected by NMR corresponded to those noted by 2-dimensional echocardiography and contrast angiography. Sensitivity, specificity and accuracy for the detection of infarction were 93, 80 and 87%, respectively, when signal intensity and wall thickening abnormalities were combined. In summary, NMR imaging is feasible in patients with acute myocardial infarction within 24 hours of chest pain onset. The study can be conducted safely and it provides useful information about acute myocardial infarction.

Comparison of intravenous myocardial contrast echocardiography and low-dose dobutamine echocardiography for predicting left ventricular functional recovery following acute myocardial infarction

Akinesia after acute myocardial infarction (AMI) may be reversible or irreversible. Distinguishing these 2 entities early after AMI is difficult, but clinically important. Previous studies have shown that myocardial contrast echocardiography (MCE) and low-dose dobutamine echocardiography (DE) may both be useful in this setting. However, there are few data regarding the relative and combined value of these techniques. The aim of this study was to compare the utility of real-time intravenous MCE and low-dose DE in the early prediction of functional recovery of akinetic myocardium after AMI. Thirty-seven patients were studied 3 +/- 2 days after an AMI. Each subject underwent real-time MCE using an intravenous infusion of perflutren microbubbles. Immediately after this, low-dose DE was performed. Contrast opacification and wall motion were determined by experienced observers blinded to clinical data. Repeat echocardiograms were obtained 51 +/- 19 days later and wall motion at rest was scored by an observer blinded to clinical data. Normal contrast opacification predicted functional recovery with a positive predictive value of 63%, a negative predictive value of 73%, and an accuracy of 66%. Residual contractility during low-dose DE had a positive predictive value of 82%, a negative predictive value of 72%, and a predictive accuracy of 76%. When the 2 tests were concordant (64%), they had a positive predictive value of 81%, a negative predictive value of 85%, and a predictive accuracy of 83%. Low-dose DE was superior to intravenous MCE in the prediction of functional recovery of akinetic myocardium after AMI, but the combination of both maximizes predictive accuracy.

Relationship between HgbA1c and Myocardial Blood Flow Reserve in Patients with Type 2 Diabetes Mellitus: Noninvasive Assessment Using Real-Time Myocardial Perfusion Echocardiography

To study the relationship between glycosylated hemoglobin (HgbA1c) and myocardial perfusion in type 2 diabetes mellitus (T2DM) patients, we prospectively enrolled 24 patients with known or suspected coronary artery disease (CAD) who underwent adenosine stress by real-time myocardial perfusion echocardiography (RTMPE). HgbA1c was measured at time of RTMPE. Microbubble velocity (β min−1), myocardial blood flow (MBF, mL/min/g), and myocardial blood flow reserve (MBFR) were quantified. Quantitative MCE analysis was feasible in all patients (272/384 segments, 71%). Those with HgbA1c > 7.1% had significantly lower β reserve and MBFR than those with HgbA1c ≤ 7.1% (P < 0.05). In patients with suspected CAD, there was a significant inverse correlation between MBFR and HgbA1c (r = −0.279, P = 0.01); however, in those with known CAD, this relationship was not significant (r = −0.117, P = 0.129). Using a MBFR cutoff value > 2 as normal, HgbA1c > 7.1% significantly increased the risk for abnormal MBFR, (adjusted odds ratio: 1.92, 95% CI: 1.12–3.35, P = 0.02). Optimal glycemic control is associated with preservation of MBFR as determined by RTMPE, in T2DM patients at risk for CAD.

A Multicenter, Prospective Study to Evaluate the Use of Contrast Stress Echocardiography in Early Menopausal Women at Risk for Coronary Artery Disease: Trial Design and Baseline Findings

AIMS This multisite prospective trial, Stress Echocardiography in Menopausal Women At Risk for Coronary Artery Disease (SMART), aimed to evaluate the prognostic value of contrast stress echocardiography (CSE), coronary artery calcification (CAC), and cardiac biomarkers for prediction of cardiovascular events after 2 and 5 years in early menopausal women experiencing chest pain symptoms or risk factors. This report describes the study design, population, and initial test results at study entry. METHODS From January 2004 through September 2007, 366 early menopausal women (age 54±5 years, Framingham risk score 6.51%±4.4 %, range 1%-27%) referred for stress echocardiography were prospectively enrolled. Image quality was enhanced with an ultrasound contrast agent. Tests for cardiac biomarkers [high-sensitivity C-reactive protein (hsCRP), atrial natriuretic protein (ANP), brain natriuretic protein (BNP), endothelin (ET-1)] and cardiac computed tomography (CT) for CAC were performed. RESULTS CSE (76% exercise, 24% dobutamine) was abnormal in 42 women (11.5%), and stress electrocardiogram (ECG) was positive in 22 women (6%). Rest BNP correlated weakly with stress wall motion score index (WMSI) (r=0.189, p<0.001). Neither hsCRP, ANP, endothelin, nor CAC correlated with stress WMSI. Predictors of abnormal CSE were body mass index (BMI), diabetes mellitus, family history of premature coronary artery disease (CAD), and positive stress ECG. Twenty-four women underwent clinically indicated coronary angiography (CA); 5 had obstructive (≥50%), 15 had nonobstructive (10%-49%), and 4 had no epicardial CAD. CONCLUSIONS The SMART trial is designed to assess the prognostic value of CSE in early menopausal women. Independent predictors of positive CSE were BMI, diabetes mellitus, family history of premature CAD, and positive stress ECG. CAC scores and biomarkers (with the exception of rest BNP) were not correlated with CSE results. We await the follow-up data.

Pretest score for predicting microbubble contrast agent use in stress echocardiography: a method to increase efficiency in the echo laboratory.

Background. In stress echocardiography, contrast agents are used selectively to improve endocardial border definition. Early identification of candidates may facilitate use of these agents in small and medium volume laboratories where resources are limited. Methods. We studied 15232 patients who underwent stress echocardiography. Contrast agent was used if 2 or more ventricular segments were not adequately visualized without contrast. Logistic regression models were used to evaluate the association between individual characteristics and contrast use. An 11-point score was derived from the significant characteristics. Results. Variables associated with microbubble use were age, sex, smoking, presence of multiple risk factors, bodymass index (BMI), referral for dobutamine stress echocardiography, history of coronary artery disease, and abnormal baseline electrocardiogram. All variables except BMI were given a score of 1 if present and 0 if absent; BMI was given a score of 0 to 4 according to its value. An increased score was directly proportional to increased likelihood of contrast use. The score cutoff value to optimize sensitivity and specificity was 5. Conclusions. A pretest score can be computed from information available before imaging. It may facilitate contrast agent use through early identification of patients who are likely to benefit from improved endocardial border definition.

Harmonic imaging during contrast echocardiography: basic principles and potential clinical value

Contrast echocardiography has evolved rapidly, due to major recent advances in both contrast agent development and ultrasound equipment technology. Transpulmonary passage of intravenously administered contrast agents and resultant left ventricular opacification has been demonstrated in humans [1, 2]. Newer agents, containing various stabilizing gases, produce both left ventricular and myocardial opacification after intravenous injection in animal models during normal and altered perfusion states [3–9]. Experimental human studies indicate similar findings [10, 11], suggesting enormous potential for the clinical application of these new agents. However, the myocardial contrast effect is variably detected when imaged with standard commercially available ultrasound equipment, and if higher doses are utilized to improve detectability, attenuation from within the ventricles frequently interferes with complete visualization of the myocardium.

Effect of stress echocardiography testing on changes in cardiovascular risk behaviors in postmenopausal women: a prospective survey study.

BACKGROUND We evaluated the impact of contrast stress echocardiography (CSE) testing results on cardiovascular (CV) risk behaviors in postmenopausal women presenting with chest pain symptoms. This was a substudy of the Stress Echocardiography in Menopausal Women at Risk for Coronary Artery Disease (SMART) trial. METHODS From 2004 to 2007, 366 women (mean age 54.4 ± 5.5 years, range 40-65; body mass index (BMI) 31.4 ± 6.68; Caucasian in 95%) completed CSE and were invited to participate in the Womens Heart Clinic Risk Assessment Questionnaire (WHCRAQ survey) at the time of CSE and after 2 years. Of the 366, 203 (55%) postmenopausal women completed both the baseline and 2-year follow-up surveys (age 61 ± 5 years; Framingham risk score 6 ± 4%, 81% treadmill CSE, 19% dobutamine CSE). WHCRAQ assessed medical history, hormone therapy (HT), and CV risk behaviors (cigarette smoking history, including current smoking and mean cigarettes smoked per day; physical activity or exercise, including mean exercise minutes per week; and dietary fat intake, alcohol intake, and mean alcohol drinks per week). Abnormal CSE was defined as a new or worsening stress wall motion abnormality. Post-CSE changes in CV risk behaviors were determined by comparing baseline versus 2-year data. RESULTS Of the 203 women who completed the survey at baseline and 2-year CSE, 29 were excluded to avoid confounding effect (coronary angiography [CA] was performed during follow-up). Of 174 women (55% hypertensive, 10% diabetic, 76% hyperlipidemic, and 25% on HT), CSE was abnormal in 10%. Baseline characteristics were not significantly different in normal versus abnormal CSE, apart from diabetes (8% vs. 24%, p=0.04). Slightly more women with normal CSE were taking HT than not (27% vs. 12%, p=0.19). CV risk behaviors that were different in normal versus abnormal CSE included current smoking, alcohol drinks per week, and higher fat diet (8% vs. 24%, p=0.03; 2.5 ± 3.5 vs. 1.94±5.2, p=0.031; and 92% vs. 76%, p=0.03, respectively). Cigarette smoking decreased (mean difference of -1.5 cigarettes per day, p=0.014) in the abnormal-CSE group, whereas number of alcohol drinks per week increased (mean difference +0.38, p=0.009) in the normal-CSE group. CONCLUSION We observed an association of lifestyle changes with CSE test results in postmenopausal women.