The influence of heart rate on gated SPECT images

Hardebeck, Charles J.

doi:10.1016/j.nuclcard.2006.11.004

Journal of Nuclear Cardiology

2007

DOI: 10.1016/j.nuclcard.2006.11.004

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The influence of heart rate on gated SPECT images

Charles J. Hardebeck

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“…5,6 The net result is a relative increase in the proportion of counts obtained from the systolic phase where images trend toward a systolic pattern with thickened LV walls, a contracted LV chamber, and a decreased end-diastolic volume. 2 Since most of the available software packages use an automated three-dimensional algorithm to calculate the LVEF by endocardial edge-tracking and myocardial count density differentials between the diastolic and systolic short-axis perfusion tomograms at stress, 9 an abnormally shortened diastolic and/or a prolonged systolic phase results in an underestimated end-diastolic volume and consequently a low LVEF.…”

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Sustained supraventricular tachycardia resulting in a pattern of apparent “reverse transient ischemic dilatation” and an underestimated ejection fraction

Gadiraju

Bommireddipalli

Ahuja

et al. 2010

Journal of Nuclear Cardiology

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Case report. A 91-year-old female was referred for a single day gated stress/rest Tc-99m sestamibi myocardial perfusion imaging (MPI) for evaluation of acute-onset chest wheezing and episodic cyanotic spells lasting 5 minutes, which remitted spontaneously. Her past medical history was significant for progressive shortness of breath for 6 months, hyperlipidemia, depression, and mild dementia. She had no prior cardiac events or procedures. However, her post-admission telemetry revealed intermittent bouts of atrio-ventricular nodal re-entrant tachycardia (AVNRT) with spontaneous remissions. Her current medications included Lipitor, Effexor, meclizine, niacin, and vitamin D.A standard single low-dose rest (9.2 mCi)/highdose stress (30.0 mCi) Tc-99m sestamibi protocol was used. During rest imaging acquisition her baseline ECG showed normal sinus rhythm and a heart rate of 90 beats/min ( Figure 1). Her chest examination revealed bilateral wheezes. Therefore, she underwent a standard dobutamine pharmacologic stress test and achieved a peak heart rate of 115 beats/min (89% of maximum predicted). During the pharmacological stress, she had neither chest symptoms nor ECG changes suggestive of ischemia. The stress dose was administered 1-minute before the termination of dobutamine infusion. The post-stress SPECT acquisition was initiated 45 minutes following dobutamine infusion. During the post-stress acquisition, she complained of palpitations, and an immediate review of her ECG tracing revealed the presence of atrioventricular nodal re-entry tachycardia (AVNRT) at a rate of 140-160 bpm (Figure 2). Since there was no evidence of bronchospasm in this patient at the time of supraventricular tachycardia she was treated with 6 mg IV bolus, followed by 12 mg and 5 mg of IV metoprolol which was later followed up with a slow 12 mg of adenosine infusion to maintain her in sinus rhythm.Her post-stress and rest left ventricular (LV) perfusion tomograms demonstrated a uniform perfusion pattern. The post-stress tomograms demonstrated a markedly diminished LV cavity size compared to rest with associated thickening of the LV wall compared to the resting images, and a ''transient ischemic dilatation'' (TID) ratio of .55 (Figure 3). The TID ratio is derived from the endocardial volumes as the ratio of the average left ventricular volume at stress divided by the average volume at rest (normal range, .75-1.18), and ratios above 1.18 are considered to clinically denote stress-induced subendocardial ischemia. The mechanism involves a count-poor subendocardium on stress tomograms which appears as part of the left ventricular cavity with an external rim of slightly better perfused epicardium. The result is a relatively dilated LV cavity during stress compared to rest imaging. 1 However, scan findings in our patient were noted to be reversed to that of these described findings of TID, thus, mimicking a pattern of 'reverse TID'.The gated images showed normal LV regional wall motion, decreased LV volumes (end-diastolic volume (EDV) = 30 cc; end-sys...

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Sustained supraventricular tachycardia resulting in a pattern of apparent “reverse transient ischemic dilatation” and an underestimated ejection fraction

Gadiraju

Bommireddipalli

Ahuja

et al. 2010

Journal of Nuclear Cardiology

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A Case of Reverse Transient Ischemic Dilatation

Velankar

Polsani

Peña-Almaguer

et al. 2013

Methodist DeBakey Cardiovascular Journal

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A 65-year-old female with a past medical history of hypertension was admitted for left-sided chest pain. An electrocardiogram and three sets of cardiac enzymes were negative. Single-photon emission computed tomography (SPECT) with regadenoson was negative for ischemia. The patient was in atrial fibrillation at 131 bpm during stress imaging (Figure 1), while on rest imaging she was in sinus bradycardia at 59 bpm (Figure 2). Stress images showed a smaller left ventricular cavity (ungated volume of 32 mL) and thicker wall compared to the rest images (ungated volume of 56 mL) (Figures 3, 4). TID ratio was 0.57. Reverse TID occurs with tachyarrhythmias during stress imaging, in which a reduction in diastolic filling time and higher counts obtained during systole lead to a smaller LV size, and bradycardia during rest imaging, where longer diastolic filling time and higher counts obtained during diastole lead to a larger LV size.1, 2 The clinical significance is unknown. IntroductionTransient ischemic dilatation (TID) is a phenomenon that occurs when there is subendocardial ischemia and the post-stress tomograms show a larger left ventricular cavity size compared to the rest images. We present a rare case of reverse TID in which the opposite findings are seen. 2. Hardebeck C. The influence of heart rate on gated SPECT images. J Nucl Cardiol. 2007 Jan;14(1):e1-5. A CASE OF REVERSE TRANSIENT ISCHEMIC DILATATION

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The influence of heart rate on gated SPECT images

Cited by 2 publications

References 1 publication

Sustained supraventricular tachycardia resulting in a pattern of apparent “reverse transient ischemic dilatation” and an underestimated ejection fraction

Sustained supraventricular tachycardia resulting in a pattern of apparent “reverse transient ischemic dilatation” and an underestimated ejection fraction

A Case of Reverse Transient Ischemic Dilatation

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