The phase image: its relationship to patterns of contraction and conduction.

Abstract

SUMMARY To determine the relationship of phase changes and abnormalities of ventricular contraction and conduction, we performed phase image analysis of blood pool scintigrams in 29 patients. Eleven patients had no evidence of blood pool contraction or ECG conduction abnormalities, four had contraction abnormalities, seven had abnormal conduction and seven had abnormalities of both variables.The phase delay generally related to the degree of contraction abnormality. The mean phase delay in hypokinetic segments differed from that in normokinetic segments in the same patient (p < 0.025), the phase delay of akinetic and dyskinetic segments differed from that in normokinetic segments (p < 0.001) and the phase delay in dyskinetic segments differed from that in akinetic segments (p < 0.005), but there was a significant overlap in the phase delay in normal and hypokinetic segments. Also, in patients with conduction abnormalities, the minimal associated regional phase delay presented a phase dispersion and a pattern of contraction consistent with the pattern of conduction and different from normal.A single study performed both at rest and with stress demonstrated the effect of heart rate on phase assessment and confirmed the independent effects of contraction and conduction on phase delay. Acquisition and analytic methods should add significantly to the resolution of the phase method.EQUILIBRIUM multiple-gated blood pool scintigraphy is an accurate noninvasive method for determining ventricular size and function.1' 2 Analytic methods that use digital computer manipulation have been applied to the blood pool study to extract additional data.8' 4 Such manipulation produces functional images as the ejection fraction image, which color-codes the end-diastolic frame of the blood pool scintigram in terms of regional ejection fraction, while the stroke volume image color-codes the end-diastolic frame in terms of regional stroke volume. Recently, the phase image has been developed. MethodsPhase image analysis was performed on two series of consecutive patients, in whom blood pool scintigraphy was required clinically for the noninvasive assessment of ventricular size and function. One group included patients with a normal ejection fraction and segmental wall motion and without electrocardiographic conduction delay. A second consecutive series of patients had reduced left ventricular ejection fraction and obvious contraction abnormalities on qualitative visual blood pool assessment or significant electrocardiographic intraventricular conduction delay with QRS > 0.12 second. All patients were in normal sinus rhythm.The history of each patient was reviewed for infarction, and a 12-lead ECG was obtained on the day of scintigraphy. Electrocardiographic abnormalities were noted. Evidence of infarction was confirmed historically and supported by the presence of ECG Q waves . 0.04 second in duration. Conduction abnormalities, including evidence of left bundle branch block and right bundle branch block,7 were documented and pacemaker ar...

Localization of Accessory Pathways in Wolff-Parkinson-White Syndrome by Phase Imaging

“…Normally, phase changes begin in the sep tal region, with rapid spread to the rightventricular apex, subsequently affecting the bodies of both ventricles [8]. Location of the onset of contraction in our patients is given in table I.…”

“…In the patient with concealed ac cessory pathway the pattern of blood pool movement conformed to patterns of normal ventricular activation. Botvinick et al [8] studied 14 patients with abnormal conduc tion, among them 2 patients with WPW syn drome. Phase image analysis in these patients enabled the identification of the right-sided site of initial ventricular contraction.…”

Radionuclide Phase Imaging of Ventricular Tachycardia

“…As regional contraction and ventricular emptying follow activation after a short and fixed time interval, the pattern of regional phase (related to the pattern of contraction) will parallel that of intraventricular activa tion [4], Thus, asynchronous contraction produced by abnormal activation will be characterized by phase mapping.…”

“…This area was usually located in the anterobasal left paraseptal or in the right paraseptal segments (table 2), according to the normal location of the earliest ventricular activation [4][5][6], After induction of VT and evident shift of the pixels with the lower phase values was observed according to…”

“…Sequential regional phase mapping of radionuclide gated blood pool scintigraphy has become a widely used technique for noninvasive assessment of regional ven bundle branch block [4][5][6][7], Wolff-Parkinson-White syn drome [5,8] and artificial pacing [9], The ability of this technique to detect abnormal foci of electrical activation has been assessed in patients with ectopic ventricular beats [10] and sustained ventricular tachycardia (VT) [11][12][13][14], It has been reported that phase mapping of VT pro vides noninvasive data consistent with the electrophy siologic characteristics of this arrhythmia [11][12][13]. How ever, few data are still available on the correlation between phase mapping and the conventional electrical mapping in patients with VT [12][13][14] and controversy still exists about the actual role of radionuclide studies in this particular setting.…”