PET receptors. Counting receptors using positron emission tomography.

Motulsky, Harvey J.

doi:10.1161/01.cir.82.4.1536

Cited by 3 publications

(1 citation statement)

References 7 publications

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“…10 This is because imaging receptor ligands at a single time, as done for perfusion imaging, is a sum of all the possible states of the radioligand at that time within the imaging voxel. That is, some activity will be in the blood, some will be in the interstitial space, some specifically bound to receptors, and some nonspecifically bound.…”

Section: Article See P 365mentioning

confidence: 99%

Imaging Left Ventricular Muscarinic Receptor Heterogeneity

Caldwell

Link

2009

Circ: Cardiovascular Imaging

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A s pointed out by Mazzadi et al 1 in this issue of Circulation: Cardiovascular Imaging, parasympathetic tone plays a critical role as modulator of the cardiac sympathetic nervous system in both health and disease. Decreased tone, as reflected by decreased heart rate variability (HRV), has an important role in prognosis after myocardial infarction (MI). 2 HRV is also associated with worse outcome in some patients with heart failure. 3,4 Sudden increases in parasympathetic tone, identified by increase in HRV, may precipitate ventricular fibrillation in selected individuals. 5 Other investigators have not found any of a multitude of HRV components to be predictive of outcome. 6 The predictive value of HRV is insufficient to be used alone and must be part of a multivariate assessment. Article see p 365Given the wealth of data demonstrating that HRV and its derivatives provide useful but not highly predictive clinical information and at a relatively low cost, what added value is gained by the use of a complicated and expensive imaging method? There are limitations to measurement of HRV that generally require the patient to be in sinus rhythm without sinoatrial dysfunction, to have Յ20% ectopic beats, have good quality tracings and, ideally, at least 24 hours of recording. 2 The requirement for sinus rhythm limits it application in the largest population in which it is most likely beneficial, those with heart failure. Also, imaging of presynaptic sympathetic function has been shown to better predict adverse events. 6 The results of the Mazzadi et al 1 study suggest that imaging of parasympathetic function also may be predictive.Probably the most important rationale for the use of imaging to measure muscarinic cholinergic function relates directly to the regional heterogeneity of myocardial perfusion and sympathetic and parasympathetic function. As noted by Mazzadi et al, 1 heterogeneity appears to play a major role in the arrhythmias associated with myocardial infarction and ischemia and probably some of the nonischemic cardiomyopathies. Our own observation, using positron emission tomography (PET), that the magnitude of heterogeneity of presynaptic and postsynaptic sympathetic function is associated with adverse outcome in ischemic cardiomyopathy, supports the importance of functional heterogeneity. 7 HRV and its components reflect both systemic and global cardiac parasympathetic and sympathetic function interaction but do not distinguish between the two. Moreover, HRV cannot measure regional dysfunction. In this report, Mazzadi et al 1 make the case that there are regional differences in muscarinic receptor density in the post-MI patient, even in the absence of significant residual scar, and by inference regional differences in parasympathetic function. Their observations were made in only 11 patients and 9 normal subjects. If their observation of increased receptor density remote from MI location is substantiated in larger populations and can be related to arrhythmic events or other adverse outcome, muscarinic ima...

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Section: Article See P 365mentioning

confidence: 99%