Cardiac Sympathetic Activity in Patients With the Apical Ballooning Syndrome

Overview

Our hypothesis is that altered cardiac sympathetic activity is present and may contribute to the myocardial stunning observed in the apical ballooning syndrome. Aim: Assess the extent and reversibility of cardiac adrenergic neuronal dysfunction using carbon-11 hydroxyephedrine (C-11 HED), a positron emission tomography (PET) tracer, in patients with the apical ballooning syndrome.

General methods: Five patients will undergo PET scans within a few days of or during the initial hospital admission for apical ballooning syndrome and during follow-up at 4 to 6 weeks to evaluate regional perfusion using N-13 ammonia and cardiac sympathetic activity with C-11 HED. PET scanning protocol On the morning of the study, patients will arrive at the Mayo Clinic PET Imaging Center in a fasting state. The use of medications will be ascertained and recorded. An intravenous cannula will be placed in each arm. The subject will then be positioned in the PET scanner . After optimal positioning of the left ventricle within the field of view, a transmission scan will be performed with either a germanium-68 or CT source for subsequent attenuation correction. The PET scanning sequence is outlined below. Because 11C-HED uptake is dependent on flow characteristics, a flow study will be performed using N-13 ammonia. N-13 ammonia (10 to 20 mCi) will be injected over 20 seconds, and dynamic acquisition will be performed for 20 minutes with the following sequence:16 frames at 3 seconds, 10 frames at 12 seconds, and 2 frames at 240 seconds. Following a 50-minute period of N-13 ammonia decay, 11C-HED (20mCi) will be injected over 30 seconds, and a dynamic acquisition will be performed with the following sequence: 6 frames at 30 seconds, 2 frames at 60 seconds, 2 frames at 150 seconds, 2 frames at 300 seconds, 2 frames at 600 seconds, and 1 frames at 1,200 seconds. To correct for 11C-metabolites in the blood activity, venous samples will be drawn at 0, 1, 5, 10, 20, 40, and 60 minutes (total \~25 ml of blood) after the injection of C-11 HED. Heart rate, systemic blood pressure, and a 12-lead electrocardiogram will be obtained noninvasively with each peak isotope activity.

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