Identification of viable myocardium early after acute myocardial infarction using closed-loop arbutamine echocardiography: comparison with positron emission tomography.

Objective: This study sought to evaluate the safety and efficacy of arbutamine echocardiography in identifying contractile reserve and predicting functional improvement early after acute myocardial infarction (AMI).

Methods And Results: Seventeen patients with first AMI underwent arbutamine echocardiography 48 to 96 hours after AMI. Arbutamine was infused by a closed-loop delivery device.

The role of early measurement of nitrogen-13 ammonia uptake for predicting contractile recovery after acute myocardial infarction.

Previous studies have shown that the maintenance of cell membrane integrity and metabolism requires the persistence of residual myocardial blood flow. The purpose of this study was to assess the role of N-13 ammonia positron emission tomographic (PET) imaging performed early after an acute myocardial infarction for predicting functional recovery. Seventeen patients with an acute myocardial infarction were included in the study.

Relation between contractile reserve and positron emission tomographic patterns of perfusion and glucose utilization in chronic ischemic left ventricular dysfunction: implications for identification of myocardial viability.

Objectives: This study sought to determine the incidence and extent of dobutamine-induced contractile reserve in myocardial regions characterized by classical and new positron emission tomographic (PET) patterns in patients with chronic ischemic left ventricular dysfunction.

Background: PET is considered the most accurate method for assessment of myocardial viability, which is traditionally identified by perfusion-metabolism mismatch.

Methods: In 23 patients, segmental wall thickening expressed by four echocardiographic scores at rest and during low dose (5 and 10 microg/kg body weight per min) dobutamine infusion and regional myocardial uptake of potassium-38 and fluorine-18 fluorodeoxyglucose (F-18 FDG) during glucose clamp were compared in 16 corresponding segments.

Modeling radon progeny absorbed in glass.

The depth distribution of 214Pb and 210Pb in glass was calculated from 218Po and 214Po deposited on the surface. The activity is found in a very narrow zone near the surface (< 100 nm). A fraction of the absorbed 214Po is capable of reaching the surface by decay into 210Pb.

Immediate and long-term results of percutaneous coronary angioplasty in patients aged 70 years or older.

Percutaneous coronary angioplasty (PTCA) nowadays appears as an attractive alternative to coronary artery by-pass grafting not only in young adults, but also in elderly patients. The aim of this study was to investigate the primary success, complications and long-term efficacy of PTCA in a consecutive series of 63 patients aged 70 years or over. Results are analysed in comparison to a younger group of 423 subjects who were submitted to PTCA during the same period of time.

Effect of spinal cord stimulation on regional myocardial perfusion assessed by positron emission tomography.

Spinal cord stimulation (SCS) can relieve symptoms in patients with severe angina pectoris refractory to conventional medical or surgical therapy. This symptomatic improvement may result from decreased myocardial ischemia. To test this hypothesis, positron emission tomography (PET) and potassium-38 as a flow tracer were used in 8 patients for the quantitative evaluation of regional myocardial perfusion at rest and after exercise, before and during SCS.

Imaging of myocardial metabolism by positron emission tomography.

Tracer techniques have provided new insight in cardiology by allowing noninvasive studies of myocardial perfusion, function, metabolism, and, more recently, ligand-receptor interaction. Positron emission tomography allows accurate quantification and the use of natural substrates labelled with 11C, 13N, or 15O. Myocardial metabolism is complex and utilizes a number of substrates, primarily fatty acids.

Identification of viable myocardium by echocardiography during dobutamine infusion in patients with myocardial infarction after thrombolytic therapy: comparison with positron emission tomography.

To assess the presence of viable myocardium salvaged by coronary artery reperfusion, 17 patients with acute anterior myocardial infarction were studied. Each received intravenous thrombolysis within the first 3 h of symptoms and underwent two-dimensional echocardiography before and during dobutamine infusion (10 micrograms/kg per min) 7 +/- 4 days after admission and positron emission tomography 9 +/- 5 days after admission. Echocardiography and positron emission tomography were again performed 9 +/- 7 months later.

[Methods and clinical applications of positron emission tomography in endocrinology].

Positron emission tomography (PET) allows to detect in coincidence photons issued from annihilation between positrons and electrons nearby situated. Tomographic detection (plane by plane) and tomographic reconstruction will lead to the quantitation of radioactive distribution per voxel, in the organ of interest. Recent tomographs can acquire simultaneously several transaxial slices, with a high sensitivity and a spatial resolution of 3-5 mm.

Effect of exercise on the leg distribution of C15O2 and 15O2 in normals and in patients with peripheral ischemia: a study using positron tomography.

In order to evaluate regional muscle blood flow and oxygen utilization, we study with positron emission tomography (PET) the distribution of C15O2 and 15O2 in 17 subjects: 5 normals (24 +/- 3 years) and 12 patients (63 +/- 13.5 years). C15O2 and 15O2 are inhalated with a steady-state technique.

[Regional blood flow and oxygen consumption in the leg muscles of normal subjects and in those with arterial insufficiency. Study of the distribution of C15O2 and of 15O2 using positron emission tomography].

We first studied the distribution of radioactivity during continuous inhalation of C15O2 and 15O2 in traverse tomograms of the greatest diameter of legs, at rest and immediately after exercise (ankle flexions). C15O2 and 15O2 were distributed homogeneously and symmetrically in both legs of normal subjects at rest. The activity accumulated in the anterolateral region after exercise.

Automated production of potassium-38 for the study of myocardial perfusion using positron emission tomography.

The 35Cl(alpha, n)38K nuclear reaction was developed for the routine cyclotron production of repeated multimillicurie batches of 38K for dynamic studies of regional tissue perfusion with positron emission tomography. The objective is to make this isotope available as an alternative to the use of [13N]NH3 and 82Rb for the investigation of flow in experimental and clinical use. A sodium chloride powder target mounted on a water-cooled nickel backing is bombarded with 26 MeV helium-4 ions at a maximum beam current of 25 microA.

Rubidium-82 myocardial uptake and extraction after transient ischemia: PET characteristics.

The effects of transient regional ischemia on monovalent cation uptake and extraction by the myocardium were studied in seven open chest dogs. Following a 10-20% stenosis of the left anterior descending coronary artery to prevent reactive hyperemia, the regional myocardial uptake of the monovalent cation 82Rb (ml/min/g X extraction) was measured before, during, and at 10, 30, and 60-80 min after a 10 min total occlusion of the left anterior descending coronary artery using positron emission tomography. Regional myocardial blood flow was also measured at the same time interval using radiolabeled carbonized microspheres.

Preparation and evaluation of a hydrous tin(IV) oxide 82Sr/82Rb medical generator system for continuous elution.

Hydrous tin(IV) dioxide in the Na+-form appears to be the most efficient inorganic exchanger for a reliable and versatile clinical 82Rb generator. Continuous elution with a commercial physiological NaCl solution yields 82Rb ranging between 10 and 40% at a flow rate as low as 3 to 10 mL/min respectively. At the same time the Sr breakthrough is less than 1.

Direct effects of smoking on the heart: silent ischemic disturbances of coronary flow.

Cigarette smoking is strongly associated with ischemic heart disease and acute coronary events. The effect of smoking a single cigarette on regional myocardial perfusion was studied in 13 chronic smokers with typical stable angina pectoris using positron emission tomography and rubidium-82 (82Rb). Findings were compared with the effects of physical exercise.

Regional myocardial and organ blood flow after myocardial infarction: application of the microsphere principle in man.

A physiologic means of measuring the distribution of cardiac output and regional myocardial blood flow has been developed that uses human albumin microspheres labeled with carbon-11 (11C) and external detection with positron emission tomography. Ten patients with previous myocardial infarction were studied to investigate the level of blood flow in normal and infarcted segments of the heart. After diagnostic catheterization, 4 to 6 mCi of 11C on 2 to 3 million sterile microspheres (15 to 20 micron) were mixed and injected into the apex of the left ventricle during timed withdrawal of arterial blood to obtain reference flow values.

[Prognostic significance of the type A behavior pattern].

In a clinical study on cardiac rehabilitation, the authors point out that the outcome of coronary heart disease patient is profoundly conditioned by the intensity of Pattern A behavior. The need to modify this behavior is evident.

Myocardial blood flow and glucose uptake after myocardial infarction.

Position emission tomography can picture the distribution of flow tracers as well as of metabolic substrates or analogs. Studies of the distribution of these tracers allow to infer information about regional myocardial clearance (flow X extraction) and substrate utilization. In a study of 32 patients after myocardial infarction, we have contrasted flow and substrate utilization to demonstrate ischemic but viable myocardium in the arterial territory of the infarct in a number of patients also specially after fibrinolytic reperfusion.

Transient ST-segment depression as a marker of myocardial ischemia during daily life.

Patients with angina and coronary artery disease (CAD) have many episodes of transient ST-segment depression during ordinary daily life, and these are often asymptomatic. To investigate this signal as a marker of myocardial ischemia, 30 patients with chronic stable angina and CAD underwent positron tomography, recording the regional myocardial uptake of rubidium-82, pain and ST-segment changes before, during and after 59 technically satisfactory exercise tests, 35 cold pressor tests and 22 episodes of unprovoked ST depression. Exercise resulted in 53 episodes of ST depression with angina and in 5 episodes without pain.

Silent myocardial ischaemia due to mental stress.

Patients with angina and coronary disease have many episodes of symptomless transient myocardial ischaemia, most of which cannot be explained by physical exertion. 16 patients with typical stable angina pectoris were examined to test the hypothesis that these episodes can be triggered off by ordinary daily events, such as changes in mental activity. Regional myocardial perfusion and ischaemia were assessed by measurement of the uptake of rubidium-82 with positron tomography after mental arithmetic and physical exercise.

Validation of quantitation of regional myocardial blood flow in vivo with 11C-labeled human albumin microspheres and positron emission tomography.

Use of radiolabeled microspheres is a standard method to measure regional myocardial perfusion in animals. Human albumin microspheres have been given safely to patients, but positron-emitting 68Ga-labeled human albumin microspheres are characterized by an unstable radiolabel. A new labeling procedure that covalently binds 11C (t1/2 = 20.

Preparation of human serum [methyl-11C]methylalbumin microspheres and human serum [methyl-11C]methylalbumin for clinical use.

Safely-injectable suspensions of human serum [methyl-11 C] methylalbumin microspheres have been prepared via the reaction of human serum albumin microspheres with [11C]methyl iodide, itself prepared in a novel one-pot synthesis from cyclotron-produced [11C]carbon dioxide. The preparation takes only 30 min from the end of radionuclide production and proceeds in 22% radiochemical yield based on the activity of [11C]carbon dioxide used and decay-corrected. It has been shown that such microspheres are highly stable in vivo and may be used as reference blood flow markers in positron emission tomography (PET).