Myocardial Blood Flow by PET and N-13 Ammonia During Regadenoson Stress

The investigators propose to measure and compare regadenoson-induced hyperemic Myocardial Blood Flow (MBF) versus adenosine-induced hyperemic MBF, using PET N-13 Ammonia in healthy subjects. The protocol will provide clinically useful data for practice.

Growing clinical experience and published studies support the comparable diagnostic accuracy, safety, and better subjective tolerability of regadenoson as compared to adenosine. Furthermore, while dipyridamole and adenosine are contraindicated in patients with asthma and significant chronic obstructive pulmonary disease (COPD), pilot data suggest overall safety of regadenoson in patients with mild or moderate asthma and in patients with stable moderate COPD.

The use of the cyclotron-produced and FDA-approved PET perfusion tracer, N-13 ammonia, with regadenoson has not been published. Among the nuclear perfusion tracers, N-13 ammonia provides the best image quality, high diagnostic accuracy, and the lowest total body radiation exposure. Quantification of myocardial blood flow (MBF) in ml per min per gm is also possible with N-13 ammonia, adding clinically useful information and powerful prognostic value and is increasingly utilized in clinical practice. In studies of PET with N-13 ammonia, MBF increases up to four-fold with adenosine or dipyridamole in healthy human volunteers and normal myocardium. However, the PET acquisition protocol for N-13 ammonia with regadenoson stress and the limits of normal PET measured hyperemic blood flow after regadenoson infusion have not been published. The optimal timing of N-13 ammonia administration and of PET image acquisition as well as acquisition duration following regadenoson bolus is not known. Different physical and biological properties of PET perfusion tracers necessitate specific protocols for each tracer.

• Drug: Regadenoson
  regadenoson (0.4 mg/5 ml IV) will be administered intravenously over 10 seconds, followed immediately by saline flush
  Other Name: Lexiscan
• Drug: Adenosine
  adenosine (140 μg/kg/min) will be administered intravenously over 6 minutes
  Other Name: Adenoscan

• Active Comparator: Regadenoson
  To Assess Regadenoson stress PET N-13 Ammonia MBF.
  Intervention: Drug: Regadenoson
• Active Comparator: Adenosine
  To assess adenosine stress PET N-13 Ammonia MBF
  Intervention: Drug: Adenosine

Inclusion Criteria:

• Twelve healthy male and female volunteers over the age of 30.
• Written informed consent will be obtained from each subject.
• Each subject will undergo a history and physical examination

Exclusion Criteria:

• Any cardiovascular or pulmonary symptoms or exam findings
• History of low blood pressure (< 90/50 mmHg)
• Prior cardiac history
• History of hypertension
• History of hyperlipidemia
• History of diabetes mellitus
• History of asthma or chronic obstructive pulmonary disease
• Weight of > 450 pounds
• Chronic kidney disease
• Other serious illness such as cancer
• Current smoking
• Medication use (with the exception of acetaminophen, aspirin, NSAIDs, and thyroid hormone replacement)
• Illicit drug use
• Prior allergic reaction to adenosine, regadenoson, or aminophylline
• Pregnancy