Effect of left ventricular function on diagnostic accuracy of FDG SPECT.

Objectives: Fluorine-18 fluorodeoxyglucose (FDG) SPECT has emerged as an alternative to dedicated PET imaging. However, it remains uncertain whether FDG SPECT is an as accurate for viability assessment as FDG PET in patients with severely reduced left ventricular function. The aim of the study was to assess the diagnostic accuracy of FDG SPECT in a head-to-head comparison with FDG PET, and divide the patients according to the severity of left ventricular dysfunction.

Myocardial beta-adrenoceptor downregulation in idiopathic dilated cardiomyopathy measured in vivo with PET using the new radioligand (S)-[11C]CGP12388.

Purpose: The beta-adrenoceptor (beta-AR) plays an important role in heart failure. Recently, the new tracer (S)-[11C]CGP12388 has been developed. It displays excellent properties for investigation of the cardiac beta-ARs in vivo with positron emission tomography (PET).

Effect of attenuation correction on the interpretation of 99mTc-sestamibi myocardial perfusion scintigraphy: the impact of 1 year's experience.

The aim of this study was to determine the yield of attenuation correction in myocardial perfusion imaging (MPI), before and after a 1-year experience period. In 48 consecutive patients referred for MPI, both non-corrected (NC) and attenuation-corrected (AC) images were analysed by three independent readers shortly after implementation of attenuation correction. The same images were re-analysed 1 year later, after having obtained experience in attenuation correction on a routine basis in >500 patients with clinical feedback.

Comparison of 99mTc-sestamibi-18F-fluorodeoxyglucose dual isotope simultaneous acquisition and rest-stress 99mTc-sestamibi single photon emission computed tomography for the assessment of myocardial viability.

Dual isotope simultaneous acquisition single photon emission computed tomography (DISA SPECT) offers the advantage of obtaining information on myocardial perfusion using Tc-sestamibi ( Tc-MIBI) and metabolism using F-fluorodeoxyglucose ( F-FDG) in a single study. The prerequisite is that the Tc-MIBI images are not degraded by scattered 511 keV photons or poor count statistics due to the lower efficiency of the extra high energy (EHE) collimator. Therefore, we compared the registered Tc-MIBI uptake and image quality of DISA and single isotope acquisition.

Abnormalities in myocardial contractility, metabolism and perfusion reserve in non-stenotic coronary segments in heart failure patients.

Objective: Myocardial blood flow (MBF) reserve is impaired in congestive heart failure (CHF), while fluorine-18-deoxyglucose (18FDG) uptake is relatively preserved. To determine whether this mismatch could be interpreted as ischemia, we performed dobutamine stress echocardiography (DSE).

Methods: 12 males with coronary artery disease (CAD) and CHF were compared with 12 controls with similar CAD but normal left ventricular (LV) function.

Impairment of myocardial blood flow reserve in patients with asymptomatic left ventricular dysfunction: effects of ACE-inhibition with perindopril.

Myocardial blood flow (MBF) reserve is impaired in patients with symptomatic chronic heart failure. Whether this is already present in asymptomatic left ventricular (LV) dysfunction, and whether it is affected by angiotensin converting enzyme (ACE) inhibition, is unknown. We examined MBF in 20 patients with asymptomatic LV dysfunction and compared them to healthy volunteers.

Measurement of myocardial beta-adrenoceptor density in clinical studies: a role for positron emission tomography?

The beta-adrenoceptor (beta-AR) plays an important role in the regulation of heart function and has been extensively studied in recent decades. In vitro studies have shown down-regulation of beta-AR density in heart failure and cardiac conditions that may lead to heart failure. As in vitro measurements on cardiac tissue samples do not allow longitudinal and regional assessment of myocardial beta-ARs in humans, new methods are being developed to measure beta-ARs in vivo using positron emission tomography (PET).

Imaging of beta-adrenoceptors in the human thorax using (S)-[(11)C]CGP12388 and positron emission tomography.

We report positron emission tomography studies of beta-adrenoceptors in the human thorax with (S)-[(11)C]CGP12388 (4-(3-(2'-[(11)C]-isopropylamino)-2-hydroxypropoxy)-2H-benzimidazol-2-one). Beta-adrenoceptors have previously been quantified using (S)-[(11)C]CGP12177 (4-(3-tert-butylamino-2-hydroxypropoxy)-2H-benzimidazol-2[(11)C]-one), but (S)-[(11)C]CGP12388 is more easily prepared and therefore more suitable in a clinical setting. (S)-[(11)C]CGP12388 was administered to five healthy volunteers on two separate days (control and pindolol block study).

Positron emission tomography using(18)F-fluoro-deoxyglucose and euglycaemic hyperinsulinaemic glucose clamp: optimal criteria for the prediction of recovery of post-ischaemic left ventricular dysfunction. Results from the European Community Concerted Action Multicenter study on use of(18)F-fluoro-deoxyglucose Positron Emission Tomography for the Detection of Myocardial Viability.

Aims: To assess the accuracy of positron emission tomography to predict recovery of global cardiac function after revascularization in patients with coronary artery disease.

Methods And Results: One hundred and seventy-eight patients (157 male, 58+/-10 years) with coronary artery disease and left ventricular dysfunction (mean ejection fraction 39+/-14%) were enrolled in six European centres. They underwent a common protocol for the assessment of viability using(18)F-fluoro-2-deoxyglucose (FDG) positron emission tomography during a standardized euglycaemic hyperinsulinaemic glucose clamp before revascularization by either surgery (n=140) or angioplasty (n=38).

No difference in cardiac event-free survival between positron emission tomography-guided and single-photon emission computed tomography-guided patient management: a prospective, randomized comparison of patients with suspicion of jeopardized myocardium.

Objectives: We sought to prospectively compare nitrogen-13 (13N)-ammonia/18fluorodeoxyglucose (18FDG) positron emission tomography (PET)-guided management with stress/rest technetium-99m (99mTc)-sestamibi single-photon emission computed tomography (SPECT)-guided management.

Background: Patients with evidence of jeopardized (i.e.

Numerical simulation of the influence of a left ventricular assist device on the cardiovascular system.

The PUCA (pulsatile catheter) pump is a left ventricular assist device (LVAD) capable of unloading the left ventricle (LV) and improving coronary flow by providing a counterpulsation effect. It consists of an extracorporeal located membrane pump, coupled to a transarterial catheter that enters the body via a superficial artery and ends in the LV. Blood is aspirated from the LV and pumped in the ascending aorta through the same catheter guided by a valve system.

Development of acute ischemic heart failure in sheep.

The goal of the present study was to develop a large animal model of acute ischemic left ventricular heart failure (LVHF) that can be used to assess the influence of the PUCA pump on the heart and circulatory system under realistic conditions. We tested the hypothesis that mild stenosis of the coronary artery in combination with mild ventricular pacing induces an acute heart failure condition, whereas the separate phenomena themselves do not lead to impaired heart function. Mean aortic pressure (AoP), left ventricular end-diastolic pressure (LVEDP), stroke volume (SV) and myocardial systolic shortening (MSS) were compared 30 minutes after a pacemaker (PM) induced tachycardia in anaesthetized sheep (n=3) without and with +/- 50% stenosis of the proximal LCx.

Regional myocardial blood flow reserve impairment and metabolic changes suggesting myocardial ischemia in patients with idiopathic dilated cardiomyopathy.

Objectives: We performed positron emission tomography (PET) to evaluate myocardial ischemia in patients with idiopathic dilated cardiomyopathy (IDC).

Background: Patients with IDC have anatomically normal coronary arteries, and it has been assumed that myocardial ischemia does not occur.

Methods: We studied 22 patients with IDC and 22 control subjects using PET with nitrogen-13 ammonia to measure myocardial blood flow (MBF) at rest and during dipyridamole-induced hyperemia.

Evaluation of the optimal driving mode during left ventricular assist with pulsatile catheter pump in calves.

The pulsatile catheter (PUCA) pump, a left ventricular assist device, was tested during acute experiments in calves using asynchronous and ECG-synchronous assist modes. The aim of the study is to compare ECG-synchronous and asynchronous assist and to find the optimal driving mode for the PUCA pump with respect to left ventricular myocardial oxygen consumption (LV MVO2), pump flow, and coronary flow. LV MVO2 decreased significantly during the asynchronous (from 7.

Automated ejection fraction determination from gated myocardial FDG-PET data.

Background: The aim of this study was to determine the potential of the automated calculation of the left ventricular ejection fraction from gated myocardial positron emission tomography (PET) scans.

Methods: We retrospectively analyzed the data of 20 patients who underwent both gated fluorine 18 deoxyglucose (FDG)-PET and equilibrium radionuclide angiography (ERNA). Gated PET data were analyzed by 2 independent programs (ie, quantitative gated single photon emission computed tomography [QGS]) originally developed for gated single photon emission computed tomography studies and functional polarmap (FPM) originally developed for the analysis of (functional) dynamic PET studies.

Left ventricular beat to beat performance in atrial fibrillation: dependence on contractility, preload, and afterload.

Objective: To assess independent determinants of beat to beat variation in left ventricular performance during atrial fibrillation.

Design: Prospective study.

Setting: University hospital.

Parametric polar maps of regional myocardial beta-adrenoceptor density.

Unlabelled: Quantification of myocardial beta-adrenoceptor density (Bmax) is of interest in cardiac diseases in which altered function of the sympathetic nervous system is thought to play a pathophysiological role. PET provides an unrivaled means of taking regional measurements of cardiac microcirculatory function, tissue metabolism and autonomic nervous system activity. Measurements in small regional areas may be biased because of increased noise levels.

Ischemia and left ventricular dysfunction: a reciprocal relation?

There is convincing evidence that (prolonged) episodes of myocardial ischemia lead to impairment of left ventricular (LV) function and ultimately to chronic congestive heart failure (CHF), but whether the opposite is also true has not been well established. We studied this issue in two groups of CHF patients with positron emission tomography (PET) by using [13N]ammonia (13NH3) as a tracer. In the first protocol we compared 12 patients with idiopathic dilated cardiomyopathy (who have normal coronary arteries) with 12 healthy controls.

A mathematical model for the heterogeneity of myocardial perfusion using nitrogen-13-ammonia.

Unlabelled: Heterogeneity of left ventricular myocardial perfusion is an important clinical characteristic. Different aspects of this heterogeneity were analyzed.

Methods: The coefficient of variation (v), characterizing heterogeneity, was modeled as a function of the number of segments (n), characterizing spatial resolution of the measurement, using two independent pairs of mutually dependent parameters: the first pair describes v as a power function of n, and the second pair adds a correction for n small.

Development of a numerical simulation model of the cardiovascular system.

A numerical simulation model of the cardiovascular system has been developed. It consists of a model of the left atrium, the left ventricle, the coronary vascular system, the aorta, the arterial system, and the venous system. The input of the complete model is the elastance (pressure/volume ratio) developed by the left ventricle.

Relative changes in regional cerebral blood flow during spinal cord stimulation in patients with refractory angina pectoris.

Spinal cord stimulation applied at thoracic level 1 (T1) has a neurally mediated anti-anginal effect based on anti-ischaemic action in the myocardium. Positron emission tomography was used to study which higher brain centres are influenced by spinal cord stimulation. Nine patients with a spinal cord stimulator for angina pectoris were studied using H(2)(15)O as a flow tracer.