The human heart is divided into four chambers. One of the four chambers, the left
ventricle, is the chamber mainly responsible for pumping blood out of the heart into the
circulation. Diseases of the heart like congestive heart failure (CHF), can cause the left
ventricle to function improperly.
Medications called beta-blockers appear to reverse the abnormalities in the left ventricle
and frequently improve the function of the left ventricle in patients with different kinds
of heart disease. How beta-blockers improve left ventricle function is unknown.
One possible reason for improved function of the left ventricle with beta-blockers is
improved blood flow to the heart muscle. When a region of the heart is active, it uses more
fuel in the form of oxygen and sugar (glucose). As heart activity increases, blood flow to
and from the area of activity increases also. Knowing these facts, researchers can use
radioactive sugar (glucose) and positron emission tomography (PET) scans to observe what
areas of the heart are receiving more blood flow.
In this study researchers plan to measure glucose use in heart muscle and blood flow to the
heart muscle in patients with CHF taking beta-blockers.
Deterioration in left ventricular function, which is characteristic in patients with
congestive heart failure, appears to be a multifactorial process. Beta-blockers appear to
reverse the deterioration and frequently improve left ventricular function in patients with
both ischemic and non-ischemic cardiomyopathies. The mechanism by which beta-blockers
improve ejection fraction is not known. Although it is well established that regional flow,
function and metabolism may improve after coronary revascularization whether beta-blocker
therapy will have similar salutary results in patients with congestive heart failure is
unknown. The aim of this study is to: 1) quantitate regional glucose uptake and regional
blood flow before and after chronic beta-blocker administration to patients with congestive
heart failure using positron emission tomography, 2) determine if alteration in either
regional glucose or lipid uptake or regional blood flow correlate with improvement in wall
motion and global left ventricular function, and 3) determine if ischemic and nonischemic
myocardium differ in blood flow or metabolism.
Left ventricular ejection fraction by radionuclide angiography of less than or equal to
New York Heart Association class II, III or IV symptoms on standard heart failure
medications which my include digoxin, diuretics and angiotensin converting enzyme
inhibitors for at least one month prior to enrollment.
Ischemic cardiomyopathy if enzymes document an MI or 70% or greater stenosis in one major
Dilated cardiomyopathy-if no coronary disease.
No pregnant or lactating women.
No women of child-bearing age not on proven birth control.
No severe hepatic or renal disease.
No diabetes mellitus or fasting glucose greater than or equal to 120 mg/dl.
No primary valvular heart disease.
No PTCA or CABG within 3 months of enrollment.
No history of myocardial infarction or unstable angina within past 2 months.
No resting heart rate less than 60 bpm.
No A-V block greater than 1 degree block without pacemaker.
No severe ETOH abuse within 6 months of enrollment.
No severe bronchospasm.