Thomas R Behrenbeck

• MD, Ph.D.
• Mayo Foundation for Medical Education and Research

Intramyocardial microvessels demonstrate functional changes in cardiomyopathies. However, clinical computed tomography (CT) does not have adequate spatial resolution to assess the microvessels. Our hypothesis is that these functional changes manifest as altered heterogeneity of the spatial distribution of arteriolar perfusion territories. Our goal...

Objective To assess the diagnostic capability of handheld echocardiography (HHE) compared with transthoracic echocardiography (TTE) performed and evaluated by experienced sonographers and expert echocardiographers. Patients and Methods We conducted a prospective study of adult outpatients undergoing comprehensive TTE between July 9, 2012, and Apri...

Aim: The effect of a one-time visit to a cardiovascular health clinic (CVHC) on weight change remains unknown. Our study examined the effects of such a visit for subjects undergoing medical and preventive evaluations. Methods: The study screened 836 subjects with a baseline BMI>25 kg/m2 and a follow-up weight at least 6 months from the initial v...

Intramyocardial microvessels show functional changes in early stages of atherosclerosis prior to epicardial coronary artery stenosis. However, clinical CT does not have adequate spatial resolution to resolve the microvessels. To clinically detect changes in the function of the intramyocardial microcirculation, the spatial heterogeneity of the distr...

Abstract Stress and its attendant psychosocial and lifestyle variables have been associated with coronary artery disease (CAD), yet the contribution of socioeconomic status (SES) has not been addressed. The aim of this study is to determine if stress assessment is associated with CAD independent of SES, and is incremental to the Framingham Score. T...

Limited data exist on the long-term outcomes of patients who undergo evaluation in a chest pain unit (CPU). Our study included patients with chest pain at intermediate risk for acute cardiovascular events enrolled in the CHEER study. The primary outcome included a composite of death, myocardial infarction, acute heart failure, stroke, and out-of-ho...

To determine the long-term outcome of computed tomographic (CT) quantification of coronary artery calcium (CAC) used as a triage tool for patients presenting with chest pain to an emergency department (ED). Patients (men aged 30-62 years and women aged 30-65 years) with chest pain and low-to-moderate probability of coronary artery disease underwent...

Peripheral arterial, endothelium-dependent, flow-mediated reactive hyperemia is reduced in individuals with atherosclerosis. This study tested the hypothesis that digital tonometry, as a surrogate of endothelial function, is useful to stratify cardiovascular risk in recently menopausal women who are asymptomatic for cardiovascular disease. Women un...

PURPOSE: The prevalence of pulmonary hypertension (PH) in patients referred for treadmill stress echocardiography is not well defined. METHODS: A total of 2,306 patients (exclusions: <18 years, significant valvular disease, a history of coronary artery disease, left ventricular (LV) ejection fraction <50%, and atrial fibrillation/flutter) were eval...

PURPOSE:The prevalence of exercise-induced pulmonary hypertension (PH) and its associated characteristics and significance are not known. METHODS:A total of 1,053 patients (pts) with normal (<35 mm Hg) Doppler-derived right ventricular systolic pressures (RVSP) underwent clinically indicated treadmill exercise echocardiography. Exclusions were age...

While the risk for symptomatic atherosclerotic disease increases after menopause, currently recognized risk factors do not identify ongoing disease processes in low-risk women. This study tested the hypothesis that circulating cell-derived microparticles may reflect disease processes in women defined as low risk by the Framingham risk score. The co...

Atherogenic processes increase in women after menopause, when the risk of cardiovascular adverse events approaches that observed in age-matched men. In experimental animals, ovariectomy increases the platelet content of mitogenic cytokines, such as platelet-derived growth factor (PDGF), which when released into the blood or site of vascular injury,...

Obstructive sleep apnea (OSA) is associated with coronary risk factors, but it is unknown if OSA is associated with development of coronary disease. We evaluated the association between OSA and the presence of subclinical coronary disease assessed by coronary artery calcification (CAC). Consecutive patients with no history of coronary disease who u...

Secondary hypertension affects a small but significant number of the hypertensive population and, unlike primary hypertension, is a potentially curable condition. The determinant for workup is dependent on the index of suspicion elicited during patient examination and treatment. Specific testing is available and must be balanced depending on the ri...

The feasibility of classifying ultrasound images of intracardiac tumors and thrombi with a neural network-based algorithm was compared with the performance of experienced echocardiographers. The neural network used statistical descriptors of the apparent echocardiographic texture of the masses, and the blinded echocardiographers were given photogra...

Historically, techniques of dissection have been used to aid in our understanding of human anatomy, physiology, and pathology. However, these techniques alter the structures and fine details being studied. New advances in computer technology, imaging equipment, data acquisition, processing, storage, and display now allow multidimensional imaging. I...

The potentially life-threatening condition of methemoglobinemia is characterized by cyanosis, low pulse oximetric readings, and normal arterial Po(2) values. Acquired methemoglobinemia has been linked to the use of the topical anesthetic benzocaine in endoscopic procedures, including transesophageal echocardiography (TEE). Yet, the incidence of ben...

To define accurate and normal range of echocardiographic left atrial (LA) volume measurement and to assess the prevalence, determinants, and outcome implications of LA enlargement in mitral regurgitation (MR). We prospectively compared LA volume obtained simultaneously by electron beam-computed tomography (EBCT) and by four echocardiographic method...

To retrospectively determine whether calcium scores of the abdominal aorta obtained during computed tomographic (CT) colonography relate to Framingham risk factors and clinical cardiac events. The institutional review board approved the current HIPAA-compliant retrospective study and waived informed consent. Between 1995 and 1998, 480 patients unde...

A total of 59 patients (> or = 65 years of age) with normal left ventricular function (ejection fraction > 50%) and varying degrees of aortic valve structure and hemodynamics (normal to severely stenotic) were screened; 50 were subsequently enrolled. Continuous wave Doppler echocardiography in the descending thoracic aorta showed two general patter...

Polycystic ovary syndrome (PCOS), a common endocrine disorder of reproductive-aged women, is associated with multiple risk factors for coronary heart disease (CHD), such as diabetes mellitus, dyslipidemia, visceral obesity, and hypertension. However, premature coronary atherosclerosis has not been demonstrated in PCOS women. Electron beam computed...

To study the role of the coronary microcirculation in response to different-sized microemboli, we measured changes in intramyocardial microvascular blood volume (Bv), perfusion (F) and transit time (TT) and also microvascular patterns of injury. Bv, F and TT were quantitated in 24 pigs at baseline and again 2 min after repeat injections of 10- or 1...

Left ventricular ejection fraction was measured during the same technetium-99m sestamibi study in 239 patients by first-pass and gated single-photon emission computed tomographic methods. There was a significant difference between left ventricular ejection fraction values recorded by the 2 methods between men and women that was independent of age,...

To evaluate the ability of electron-beam computed tomography (CT) to help quantify long-term changes in coronary microvascular functional reserve in a porcine model. Electron-beam CT-based intramyocardial blood volume and perfusion and Doppler ultrasonography (US)-based intracoronary blood flow were obtained in 13 pigs at baseline and again 3 month...

The study compared the performance of conventional endocardial and epicardial centroid algorithms with the new "myocardial" centroid algorithm in patients with anterior myocardial infarction. "Floating" endocardial or epicardial centroid algorithms, commonly used in tomographic imaging methods to assess regional motion, may misrepresent left ventri...

To evaluate the reproducibility of coronary calcium quantification algorithms by electron beam CT (EBT) in patients with different amounts of calcified plaque using the conventional (Agatston) score and an area score and to demonstrate a potential application of these results for evaluation of follow-up scans. In 50 consecutive patients. the conven...

New therapeutic strategies in interventional cardiology and electrophysiology involve the coronary veins. This study examines the potential usefulness of electron beam computed tomography to obtain detailed noninvasive definition of the coronary venous anatomy and of arteriovenous relationships. Electron beam computed tomography allows acquisition...

Quantitative assessment of 3-D regional heart motion has significant potential to provide more specific diagnosis of cardiac malfunction than currently possible. Using functional parametric mapping, regional myocardial motion during a cardiac cycle can be color-mapped onto a deformable heart model to provide better understanding of the structure-to...

We previously demonstrated that in vivo electron-beam computed tomography (EBCT)-based indicator-dilution methods provide an estimate of intramyocardial blood volume (BV) and perfusion (F), which relate as BV=aF+b radicalF, where a characterizes the recruitable (exchange) and b the nonrecruitable (conduit) component of the myocardial microcirculati...

The feasibility of classifying ultrasound images of intracardiac tumors and thrombi with a neural network-based algorithm was compared with the performance of experienced echocardiographers. The neural network used statistical descriptors of the apparent echocardiographic texture of the masses, and the blinded echocardiographers were given photogra...

Electron beam computed tomography (EBCT) allows visualization and quantification of calcium in the coronary arteries. This has been demonstrated to correlate well with the overall plaque burden in the coronary arteries. EBCT is, therefore, well suited for the detection of early stages of coronary atherosclerosis. Especially in asymptomatic patients...

The growing interest in coronary calcium quantification by electron-beam CT (EBCT) has led to the development of various software systems for the analysis of EBCT raw data, but it is unknown whether these software systems yield comparable results. Two sets of EBCT scans were obtained in 73 asymptomatic patients less than 15 minutes apart. Both scan...

Electron beam computed tomography (EBCT) allows viszalization and quantification of calcium in the coronary arteries. This has been demonstrated to correlate well with the overall plaque burden in the coronary arteries. EBCT is, therefore, well suited for the detection of early stages of coronary atherosclerosis. Especially in asymptomatic patients...

The goal of this study was to compare measurements of left ventricular (LV) ejection fraction (EF) by first-pass radionuclide angiography ("first-pass angiography") using technetium-99m (Tc-99m) sestamibi with those by contrast-enhanced electron beam computed tomography ("electron beam tomography") as a reference technique in patients with an anter...

The purpose of this study was to determine if electron beam computed tomography (EBCT) has potential as a cost-effective approach to diagnosis of obstructive coronary disease. Coronary calcification quantified by EBCT is closely related to the extent of atherosclerosis. A model based upon published sensitivities (Se)/specificities (Sp) for diagnosi...

SPECT Tc^99m sestamibi imaging (SESTA) is used to assess myocardial perfusion. Few reports document SESTA left ventricle muscle mass (LVMM). This study compared the results of LVMM by electron beam CT, (EBCT) to that by SESTA SPECT. Thirty patients from a myocardial infarct study had ungated SESTA images acquired on Elscint SPECT gamma ca...

The authors sought to determine, using a variety of regional left ventricular ejection fraction (EF) and wall thickening (WTh) criteria, the applicability to measure left ventricular (LV) infarct size using electron-beam CT (EBCT) in patients as compared with technetium 99m (99mTc) sestamibi scanning as reference standard. Twelve patients (age 57 +...

Historically, techniques of dissection have been used to aid in our understanding of human anatomy, physiology, and pathology. However, these techniques alter the structures and fine details being studied. New advances in computer technology, imaging equipment, data acquisition, processing, storage, and display now allow multidimensional imaging. I...

Knowledge of left ventricular ejection fraction has been shown to provide diagnostic and prognostic information in patients with known or suspected heart disease. In clinical practice, the ejection fraction can be determined by using one of the five currently available imaging techniques: contrast angiography, echocardiography, radionuclide techniq...

Background: Electron beam CT (EBCT) can acquire rapid, multiple thin-section tomograms of the beating heart in synchrony with the electrocardiogram and quantity coronary calcification without intravenous contrast. Coronary calcification is an active process exclusively associated with atherosclerotic plaque formation and regulated in a manner simi...

Background: Electron beam CT (EBCT) can acquire rapid, multiple thin-section tomograms of the beating heart in synchrony with the electrocardiogram and quantify coronary calcification without intravenous contrast. Coronary calcification is an active process exclusively associated with atherosclerotic plaque formation and regulated in a manner simil...

Variations in blood volume in the myocardium through the cardiac cycle have previously been considered constant. More recent studies have indicated a considerably variation from end diastole to end systole. These studies were nearly all performed under non-physiological conditions using muscle preparations or ex situ cardiac preparations. This stud...

An algorithm is described for delineation and three-dimensional (3D) reconstruction of the left ventricular (LV) cavity boundary from echocardiographic images. The algorithm combines advanced image analysis and neural network techniques with a priori knowledge about LV shapes. Minimal user interaction is required to initiate the process which resul...

Electron beam computed tomography is unparalleled in its ability to consistently produce high quality dynamic images of the human heart. Its use in quantification of left ventricular dynamics is well established in both clinical and research applications. However, the image analysis tools supplied with the scanners offer a limited number of analysi...

Following myocardial infarction, the size of the infarcted region and the systolic functioning of the noninfarcted region are commonly assessed by various cross- sectional imaging techniques. A series of images representing successive phases of the cardiac cycle can be acquired by several imaging modalities including electron beam computed tomograp...

Primary ovarian carcinoid tumors are uncommon, and carcinoid heart disease is a rare complication. Although carcinoid syndrome and carcinoid heart disease typically occur in the setting of metastatic carcinoid tumor, particularly involving the liver, this is not necessarily the case in patients with primary ovarian carcinoid tumors. After surgical...

In the latter 1970s, largely due to the development of echocardiography and the ready availability of invasive contrast ventriculography, clinicians noted that distinct and serial changes occurred in the heart after infarction where cardiac enlargement could progress long after completion of scarring in the infarct region. Similar changes have also...

In the latter 1970s, largely due to the development of echocardiography and the ready availability of invasive contrast ventriculography, clinicians noted that distinct and serial changes occurred in the heart after infarction where cardiac enlargement could progress long after completion of scarring in the infarct region. Similar changes have also...

This study was designed to serially assess time-dependent changes in both chamber volume and myocardial muscle mass after infarction in humans. Dilation of the left ventricular chamber has been previously described after transmural myocardial infarction. Global left ventricular chamber volumes and muscle mass were quantified by using cine computed...

The purpose of this study was to determine the relationship of changes in the severity and extent of hypoperfusion on serial tomographic 99mTc-sestamibi images with patency of the infarct related artery during acute myocardial infarction. We studied 109 patients with acute myocardial infarction using tomographic 99mTc-sestamibi imaging acutely and...

Previous studies have shown that tomographic perfusion imaging with technetium-99m sestamibi (RP-30A) can accurately measure the myocardium at risk during acute myocardial infarction. The ability of coronary angiography to predict the wide variability in myocardium at risk was studied in 21 patients with their first acute myocardial infarction. In...

The 12-lead electrocardiogram in 23 patients with an evolving first myocardial infarction (12 anterior and 11 inferior) was correlated with the myocardial area at risk measured by tomographic perfusion imaging with technetium-99m sestamibi. Of several electrocardiographic factors, only the extent and quantity (with and without R-wave normalization)...

Twenty patients with a first acute myocardial infarction (AMI) (15 anterior, 5 inferior) who received successful reperfusion therapy underwent tomographic imaging with technetium-99m (Tc-99m) sestamibi and radionuclide ventriculography at discharge, 6 weeks, and 1 year after AMI. Patency of the infarct-related artery after reperfusion (thrombolysis...

To assess the ability of the 12-lead electrocardiogram to estimate infarction size after reperfusion therapy for acute myocardial infarction. The presence or absence of Q waves and the Selvester QRS score obtained before and after hospital discharge were compared with radionuclide estimates of infarction size and ejection fraction at discharge and...

Technetium-99m-hexakis-2-methoxy-2-isobutyl-isonitrile (technetium-99m isonitrile) is a new radiopharmaceutical compound that reflects myocardial perfusion. Its kinetics, especially its lack of redistribution after intravenous administration, permits the assessment of changes in myocardial perfusion without delay of therapy. Tomographic images at r...

Quantitation of perfusion defect size using tomographic imaging with technetium-99m-hexakis-2-methoxy isobutyl isonitrile was performed at the time of hospital discharge in 32 patients with a first myocardial infarction who underwent successful coronary reperfusion within 8 h of the onset of chest pain. Reperfusion was accomplished with thrombolysi...

A patient with symptoms of acute myocardial infarction but ST-segment depression rather than elevation constitutes a clinical dilemma for which few guidelines exist. Herein we describe such a patient, in whom serial tomographic imaging with a new radiopharmaceutical agent, technetium-99m sestamibi, was useful in demonstrating a large area of myocar...

Resting tomographic myocardial perfusion images using technetium-99m-hexakis-2-methoxy-2-methylpropyl-isonitrile (Tc-Sestamibi) were obtained in 25 patients during their first myocardial infarction. Tc-Sestamibi was injected intravenously before acute reperfusion therapy, and repeated twice, at 18-48 hr, and at 6 to 14 days. Reperfusion was success...

Measurement of myocardial perfusion with fast CT, using venous injections of contrast, underestimates high flow rates. Accounting for intramyocardial blood volume improves the accuracy of such measurements but the additional influence of different contrast injection sites is unknown. To examine this, eight closed chest anesthetized dogs (18-24 kg)...

99mTc-hexakis-2-methoxy-2-methylpropyl-isonitrile (Tc-Sestamibi), a new myocardial perfusion radiopharmaceutical, was injected intravenously in 11 patients within 4 hours of the onset of acute myocardial infarction before treatment with intravenous tissue-type plasminogen activator and 6-14 days later. Five patients with acute myocardial infarction...

Technetium-99m isonitrile is a new myocardial perfusion imaging agent that accumulates according to the distribution of myocardial blood flow. However, unlike thallium-201, it does not redistribute over time. This imaging agent was used with serial quantitative planar imaging to assess the initial risk area of infarction, its change over time and t...

In 11 patients (2 female, 9 male) suffering from angiographically proven CHD (age 45-60 years; 54.3 years on an average) the efficacy of a once-daily oral medication with 120 mg ISDN/50 mg ISMN and diltiazem (D) each in a long-acting preparation was examined in a placebo-controlled study. Each period lasted for 3 days; 2 capsules were given at 0700...

In this study prophylactic antiarrhythmic effects of verapamil on exercise-induced ventricular arrhythmias are evaluated. Investigations were carried out on a total of 22 patients. All patients showed frequent and/or complex ventricular arrhythmias during repeated exercise tests under control conditions. After two control exercise tests all patient...

In this study prophylactic antiarrhythmic effects of verapamil on exercise-induced ventricular arrhythmias were evaluated in a total of 22 patients. All patients displayed frequent and/or complex ventricular arrhythmias during repeated exercise tests under control conditions. After two control exercise tests, all patients were treated with 120 mg v...

Diprafenone is a new antiarrhythmic agent currently under clinical investigation, with close chemical similarity to propafenone. In this study, the electrophysiological and haemodynamic effects of the compound were investigated both in animals, by experiment, and in man. Diprafenone produces a dose-dependent prolongation of conduction in all parts...

Diprafenone is a new antiarrhythmic drug with a dominant local anaesthetic action and an additional beta-sympathicolytic activity. In this study, the results of long-term treatment (8 months on average) obtained from 27 patients with chronic ventricular arrhythmias are reported. Before diprafenone, all patients were treated unsuccessfully with flec...

Distances between percutaneously inserted apical and basal lung markers determined by biplane X-ray, computer-based videometry (J. Appl. Physiol. 34: 544, 1973) were calibrated against dependent percutaneously recorded pleural liquid pressures (J. Appl. Physiol. 31: 277, 1971) in five 10-12 kg mongrel dogs under morphine-pentobarbital anesthesia st...

Spatial, density, and temporal resolution of the dynamic spatial reconstructor (DSR), a multiple X-ray source, high speed, computed tomography scanning system, are evaluated. Hole-pair resolution was evaluated in a stationary phantom surrounded with air, 15 cm of water, or 20 cm of water. Temporal resolution was evaluated by rotation of one of the...

In late 1979, the Dynamic Spatial Reconstructor (DSR), a multiple x-ray source, stop action, volume scanning imaging device was installed (1, 2). At present, the operational characteristics and biomedical utility of the Dynamic Spatial Reconstructor (DSR) are being evaluated. This research project involves scanning experimental animals and carefull...