The use of perfusion scintigraphy to differentiate proximal right coronary artery stenosis from distal right coronary artery stenosis in patients with inferior left ventricular ischaemia

OBJECTIVE: The identification of patients with a significant proximal right coronary artery (RCA) is of clinical relevance since it may direct diagnostic and therapeutic strategies. This study was performed to determine parameters of (201)Tl RV perfusion SPECT which can be used to discriminate between proximal and distal RCA stenosis in patients with inferior left ventricular (LV) ischaemia. In addition, feasibility and reproducibility of a new semi-quantitative method for the assessment of RV perfusion were evaluated. METHODS: Inferior LV ischaemia was due to a single distal RCA stenosis in 10 (group I) and proximal RCA stenosis in 27 patients (group II). Twenty patients with normal (201)Tl myocardial perfusion scintigraphy and low likelihood of cardiovascular disease were used as a reference (group III). RESULTS: RV (201)Tl stress uptake did not differ between the three groups. However, group II showed a significantly higher (201)Tl rest uptake indicating RV redistribution whereas in group I and III tracer washout was shown. Extent and severity of LV inferior ischaemia was not different between groups I and II. RV redistribution has a sensitivity of 0.74, a specificity of 0.80, and an overall agreement of 0.76 for detecting proximal RCA stenosis. The feasibility of the assessment of RV (201)Tl perfusion was 94%. Inter-observer and intra-observer coefficients of variation for RV (201)Tl perfusion assessment were 1.5 and 2.4%, respectively. CONCLUSION: RV (201)Tl perfusion scintigraphy is feasible and reproducible. RV (201)Tl redistribution can be used to discriminate between proximal and distal RCA stenosis in patients with inferior LV ischaemia.     

Symptom improvement after upgrade from right ventricular apical to biventricular pacing: Role of right and left ventricular volumes assessed with single-photon emission computed tomographic equilibrium radionuclide angiocardiography

Background

In patients with heart failure and reduced left ventricular ejection fraction (LVEF), the effect of upgrading from right ventricular (RV) apical to biventricular pacing on RV and left ventricular (LV) volumes and ejection fraction (EF) is unknown. Also, the relationship of symptom improvement after biventricular upgrade to RV and LV volumes and EF has not been clarified.

Methods and Results

Nineteen patients with long-standing persistent RV apical pacing who had heart failure symptoms and echocardiographic LVEF of 0.40 or less underwent upgrade to biventricular pacing. Patients had single-photon emission computed tomographic equilibrium radionuclide angiocardiography immediately before and at 3-6?months after the upgrade procedure, to measure RV and LV volumes and EF. Biventricular upgrade was associated with increase in LVEF and decrease in LV end-diastolic and end-systolic volumes; right ventricular ejection fraction (RVEF) and end-diastolic and end-systolic volumes were unaltered. Patients with improvement in New York Heart Association heart failure class of I or more had larger initial LV end-diastolic volumes than patients without an improvement and had decreased LV end-diastolic and end-systolic volumes comparatively. Symptom improvement was not associated with RVEF and volume change.

Conclusion

Symptom improvement with LV remodeling, but not RV remodeling, occurs 3-6?months after biventricular upgrade in patients with heart failure.     

The effect of pulmonic and aortic constriction on regional left ventricular thickening dynamics, geometry and the radius of septal curvature. Analysis by gated computed transmission tomography

We evaluated the effects of aortic and pulmonic constriction on cross-sectional cardiac dynamics using prospectively gated computed transmission tomography (CT) in six dogs in order to evaluate 1) the effect of altering the end-diastolic trans-septal pressure gradient on the radius of septal curvature, and 2) the effect of right ventricular overload on regional left ventricular geometry and wall thickening dynamics. Cross-sectional CT data were obtained in a control state, at two incrementally higher levels of right ventricular end-diastolic pressure produced by constriction of the pulmonary artery (PA1 and PA2) and then at one higher level of left ventricular end-diastolic pressure resulting from acute aortic constriction (Ao). Using fluid-filled polyethylene catheters, we measured right and left ventricular pressures simultaneous with the image acquisition. The measured radius of septal curvature was then normalized by the calculated average radius derived from the left ventricular area at end-diastole. The end-diastolic radius of septal curvature ratio increased as delta [LVEDP-RVEDP] declined (from 1.03 +/- 0.13 at control; 1.20 +/- 0.18 PA2; 1.27 +/- 0.14 PA2 and 0.87 +/- 0.11 Ao). As this LVEDP-RVEDP gradient declined (ie, RVEDP increased in proportion to LVEDP) septal wall thickening declined (P less than 0.005), with significantly less change in left ventricular anterior or lateral wall thickening. With PA hypertension, LV end-diastolic volume and percent delta volume significantly declined (P less than 0.005) while RV end-diastolic volume increased. With PA pressure overload, septum-free wall distance declined (P less than 0.01) as did percent shortening along this dimension (P less than 0.01). We conclude that predictable changes in LV and RV dynamics occur when trans-septal pressure gradients change.(ABSTRACT TRUNCATED AT 250 WORDS)     

静息态下冠状动脉狭窄对左室壁透壁心肌灌注影响的640层CT研究

目的确定静息态下透壁心肌灌注指数(TPR)的正常值,并探讨静息态下不同分支的冠状动脉狭窄与各冠状动脉分支的不同狭窄程度对左室壁不同节段TPR的影响。方法 274例患者行Toshiba 640层CT检查,包括冠状动脉CTA及左心室室壁CT灌注(CTP)检查。根据冠状动脉狭窄程度及17节段进行分组。计算正常组及不同冠状动脉狭窄程度组之间相应节段内TPR是否存在差异,以及冠状动脉狭窄程度与相应节段TPR的相关性。结果前降支及左旋支病变对于左室壁心肌灌注影响较为明显,前降支狭窄主要影响中间段前壁(r=-0.288)、心尖段前壁(r=-0.263)及中间段间隔壁(r=-0.196),左旋支主要影响基底部前侧壁(r=-0.241)、基底部后侧壁(r=-0.279)及心尖段侧壁(r=-0.201),而右冠状动脉病变影响较小,主要影响中间段后壁(r=-0.195);冠状动脉中、重度狭窄组对于左室壁心肌灌注影响程度较大(P<0.05),轻度狭窄影响较小;左室前壁心肌灌注最易受到冠状动脉狭窄影响;在静息状态下前降支供血区域组、左旋支供血区域组及右冠状动脉供血区域组正常心肌和重度狭窄心肌平均TPR值分别为1.14±0.09和1.07±0.13、1.13±0.11和1.06±0.14、1.15±0.14和1.10±0.12。结论不同冠状动脉分支狭窄分别可以影响不同节段的心肌透壁灌注;不同冠状动脉狭窄程度可以不同程度地影响心肌的TPR,二者具有相关性;静息状态下TPR正常值大于负荷状态下TPR。本研究提供了TPR静息态下的正常值。     

Magnetic resonance imaging of athlete's heart: myocardial mass, left ventricular function, and cross-sectional area of the coronary arteries

To evaluate left ventricular myocardial mass and function as well as ostial coronary artery cross-sectional area in endurance athletes, an athlete group of 12 highly trained rowers and a control group of 12 sedentary healthy subjects underwent MR examination. An ECG-gated breath-hold cine gradient-echo sequence was used to calculate myocardial mass, end-diastolic and end-systolic volumes, stroke volume, and cardiac output, all related to body surface area, as well as ejection fraction. A 3D fat-saturated ECG- and respiratory-triggered navigator echo sequence was used to evaluate coronary arteries: left main (LM), left anterior descending (LAD), left circumflex (LCx), and right coronary artery (RCA). Cross-sectional area was calculated and divided for body surface area. Myocardial mass was found significantly larger in athlete group than in control group (p = 0.0078), the same being for end-diastolic volume (p = 0.0078), stroke volume (p = 0.0055), LM (p = 0.0066) and LAD (p = 0.0129). No significant difference was found for all the remaining parameters. Significant correlation with myocardial mass was found for LM (p < 0.001) and LAD (p = 0.0340), not for LCx and RCA. Magnetic resonance imaging is a useful tool in evaluating the myocardial hypertrophy and function of athlete's heart. Magnetic resonance angiography is a valuable noninvasive method to visualize the correlated cross-sectional area increase of the left coronary artery system. Received: 25 March 1999; Revised: 31 August 1999; Accepted: 1 September 1999     

肺心病患者左右心功能的MRI研究

目的探讨MRI评价肺心病患者左、右心功能的应用价值。资料与方法前瞻性研究18例经肺功能实验、临床检查、X线、心电图、超声心动图等影像学检查证实为合并慢性阻塞性肺病(COPD)的肺心病患者,另选取18名健康志愿者作为对照组。采用1.5 T MRI仪测量两组左、右室心功能及右室心肌质量。采用独立样本t检验测量两组间差异是否有统计学意义。结果 2例肺心病患者MRI检查时由于屏气时间长、不能配合而排除。与对照组比较,16例肺心病患者右室(right ventricle,RV)舒张末期容积(end-diastolic volume,EDV)、右室收缩末期容积(end-systolic volume,ESV)及右室心肌质量(myocardial mass,MM)明显增加(P<0.05),而右室射血分数(ejec-tion fraction,EF)明显减低(P<0.01)。左室EDV及EF显著减低(P<0.01)。结论肺心病患者随着肺动脉压升高,超过右心室的代偿能力,促使右心室扩大和右心功能衰竭,同时左心功能损伤。MRI左右心功能的测量可以评价肺心病的严重程度,为临床提供治疗的客观依据。     

TI-201 washout rate in remote normal regions in patients with prior myocardial infarction and left ventricular remodeling

BACKGROUND: Myocardial characteristics of remote normal regions in patients with myocardial infarction (MI) and left ventricular (LV) remodeling have not been fully elucidated. Thus, we investigated this issue from the viewpoint of myocardial Tl-201 dynamics. METHODS AND RESULTS: In 14 patients with prior anterior MI, 10 with inferior MI, and 14 age-matched patients with atypical chest pain served as controls; exercise stress Tl-201 SPECT and cardiac catheterization were performed. Tl-201 washout rate was calculated for 8 myocardial segments, and LV end-diastolic volume index was obtained as a parameter of LV remodeling. LV end-diastolic volume index was greater in anterior MI patients than in control patients; in contrast, no significant difference was observed between inferior MI patients and control patients. The washout rate in remote normal regions was significantly less in anterior MI patients than in the corresponding segments in control patients (39.8% +/- 8.7% vs 48.4% +/- 4.4%, P < .01). There was no significant difference between inferior MI patients and control patients (43.6% +/- 6.9% vs 47.8% +/- 4.5%). CONCLUSIONS: Reduced Tl-201 washout rates in remote normal regions are found in patients with anterior MI and LV remodeling. Subclinical myocardial ischemia during exercise in remote normal regions exists and may be related to the pathologic condition of such LV walls.     

Serial MRI evaluation of cardiac structure and function in mice after reperfused myocardial infarction.

This study evaluated the utility of cardiac MRI for assessing the impact of myocardial infarction (MI) on cardiac structure and function in mice following reperfused 1- or 2-hr occlusions of the left anterior descending coronary artery (LAD). When assessed 1 day after MI, the left ventricular ejection fraction (LVEF) had declined by more than half, and remained depressed for the duration of the study. Furthermore, MI initiated dramatic increases in both LV end-systolic volume (LVESV) and end-diastolic volume (LVEDV), with a greater than threefold increase in LVESV and a twofold increase in LVEDV by 4 weeks post-MI. Transmural LV wall thickening (WTh) analysis revealed that noninfarcted myocardium in the remote septal region exhibited an early deficit in contractile function after MI that transiently resolved by day 7, only to be followed by a late phase of dysfunction that became fully manifest by day 28 post-MI. In conclusion, MRI allows the serial assessment of cardiac structure and function after MI in mice, with a resolution adequate to document both regional and temporal changes. The application of these imaging techniques in transgenic and knock-out mice will greatly expedite research aimed at defining the functional roles of individual genes in the pathophysiology of LV remodeling (LVR) after reperfused MI.     

Correlation of right and left ventricular ejection fraction and volume measurements

First-pass radiocardiography and biplane angiocardiography were performed on 13 patients with left-sided regurgitant valvular disease (R+) and 7 patients without regurgitation but with coronary artery disease and/or cardiomyopathy (R-). Right and left ventricular volumes and ejection fractions were calculated and compared. In the R- group, corresponding right and left ventricular volumes and ejection fractions correlated highly with each other (r = 0.86-0.89, p approximately equal to 0.01). Ejection fractions in the R+ group correlated (r = 0.64, p less than 0.05) only because stroke volume correlation was very high (r = 0.93), with end-diastolic and end-systolic volumes showing no significant correlation. Right ventricular ejection fraction (RVEF) decreased significantly with increasing mean pulmonary artery pressure (PAP) in both R- and R+ groups. The correlation of RVEF and LVEF in the R- group appears to be multifactorial in origin, consisting of effects of increased PAP, the mechanical interference of an enlarged left ventricle on the right ventricle, and direct biventricular ischemic effects. In the R+ group, the correlation appears to be due to only increased PAP and its sequelae.     

Effect of patient imaging angle on apparent cardiac volumes and the potential impact on measurement of valvular regurgitant fractions

The accurate measurement of cardiac chamber volume is of major importance in assessing cardiac performance. Accurate equilibrium radionuclide volume estimations are difficult to obtain, due to the geometry of the chambers, and the physical characteristics of the imaging system. The purpose of this study was to examine the effects of imaging projections on relative cardiac chamber volumes, indexes, and stroke volume ratios. Twenty-two male patients, free of clinical evidence of disease, were studied. A series of four 2-minute acquisitions were made with the patient successively imaged in the anterior, 30 degrees left anterior oblique (LAO), 45 degrees LAO, and 60 degrees LAO projections with 15 degrees of caudal inclination. Filtered stroke volume and original images were used by the operator to assign right ventricular (RV), left ventricular (LV), and a combined right and left ventricular (TOT) regions-of-interest. From the data we determined end-diastolic counts (EDC), end-systolic counts (ESC), stroke counts (SC), ejection fractions (EF), and R/L stroke count ratios. The following changes were observed as the projection was moved from the anterior to 60 degrees LAO: 1) all RV parameters decreased in value, including, RVEDC (P less than .001), RVESC (P less than .01), RVESC (P less than .01) and RVEF (P less than .001); 2) LVEDC and LVESC (both P less than .01) increased while LVEF decreased (P less than .004); and 3) the R/L stroke count ratio decreased (P less than .001). Variability could be explained by 1) chamber overlap and geometry; 2) patient variability; and 3) intrachamber, interchamber and chest wall photon attenuation and scatter. We suggest that close attention to detail, with computer assistance, to optimally position the patient may reduce the effect of inherent limitations in radionuclide volumetric measurements, thus improving the reliability and usefulness of existing studies.     

Assessment of cardiac function and left ventricular regional wall motion by 99mTc multigated cardiac blood-pool emission computed tomography]

Forty-three patients underwent the analysis of left and right ventricular (LV and RV) volumes, and LV regional wall motion by multigated cardiac blood pool single photon emission computed tomography (SPECT) with 99mTc. To calculate the cardiac volume correctly, the optimal cutoff level in relation to background level was first obtained by a phantom study. Left ventricular end-diastolic, end-systolic volume (EDV and ESV) and ejection fraction (EF) calculated thus with SPECT were correlated well with the data obtained with left ventriculography (LVG) and magnetic resonance imaging (MRI), especially using horizontal long axial image. RV stroke volume (SV) without shunt or valvular diseases was also correlated well with that of LV when it was calculated using horizontal long axial image. However, SV ratio (LVSV/RVSV) was not necessarily ideal numerical 1. In addition LV wall motion was evaluated by multicontour systolic display and phase analysis in SPECT and gated planar images. The results obtained with SPECT were better correlated with those of LVG than gated planar images. It is concluded that multigated cardiac blood pool SPECT is a clinically useful method for an evaluation of cardiac function and left ventricular regional wall motion.     

"Doughnut" technetium pyrophosphate myocardial scintigrams. A marker of severe left ventricular dysfunction

The "doughnut" pattern on Tc-99m pyrophosphate (PPi) myocardial scintigraphy is characterized by a border of tracer uptake surrounding a central zone of relatively decreased activity. This pattern is generally associated with large transmural anterior myocardial infarcts (MI) caused by occlusion or critical stenosis of the left anterior descending coronary artery. Such infarcts typically involve a significant portion of the anterior wall and are associated with a complicated clinical course and poor prognosis. In order to evaluate the relationship between the presence of the doughnut pattern and left ventricular (LV) function, radionuclide ventriculography was performed within 15 days after infarction in 58 patients with transmural anterior MI. In patients without previous MI, 15/38 (39.5%) had doughnut scintigrams. These patients demonstrated significant reductions in LV ejection fraction (EF) (28 +/- 10% versus 45 +/- 12%, P less than 0.001) and normalized LV wall motion scores (29 +/- 11% versus 61 +/- 10%, P less than 0.001) when compared with patients with "nondoughnut" scintigrams. Patients with doughnut scintigrams had a significantly greater incidence of severe septal hypokinesis (P less than 0.001) and apical dyskinesis (P less than 0.03). LV end-systolic volumes were also larger in the patients with doughnut scintigrams (73 +/- 32 ml versus 40 +/- 17 mI/M2, P less than 0.005). In contrast, there was no significant difference in LVEF, normalized LV wall motion score, or LV volumes between doughnut and nondoughnut groups in patients with previous MI.     

Right ventricular function in patients with acute pulmonary embolism: analysis with electrocardiography-synchronized multi-detector row CT

PURPOSE: To prospectively assess electrocardiography (ECG)-synchronized multi-detector row computed tomography (CT) for the evaluation of right ventricular (RV) function in patients suspected of having pulmonary embolism (PE). MATERIALS AND METHODS: All patients gave informed consent after the study details, including radiation exposure, were explained; institutional ethical committee approval was obtained. Nonsynchronized multi-detector row CT of the chest was performed in 66 consecutive patients (29 men, 37 women; mean age, 58 years+/-15 [standard deviation]) who were suspected of having PE. ECG-synchronized cardiac multi-detector row CT was performed to assess cardiac function. Dimension ratios for the RV and left ventricle (LV) were measured on nonsynchronized transverse and angulated four-chamber views. Furthermore, the RV end-diastolic and end-systolic volumes were measured on ECG-synchronized multi-detector row CT scans. An independent samples t test was performed to compare the mean value of different groups. An analysis of variance post hoc test was performed to investigate whether the values of the variables varied between groups. RESULTS: PE was detected in 29 of 66 patients. The location of PE was categorized as central (n=17) or peripheral (n=12). The RV/LV dimension ratio was larger on the four-chamber view (P=.002), and RV end-systolic volume was larger (P=.01) and ejection fraction was lower (P=.01) in patients with PE. The RV end-systolic volumes and RV/LV volume ratios, as assessed by using ECG-synchronized multi-detector row CT, showed significant differences (P<.005) between patients with central PE and those with peripheral PE. However, the RV/LV dimensions on nonsynchronized images revealed no significant differences. CONCLUSION: Retrospective ECG-synchronized multi-detector row CT facilitates detection of RV dysfunction, depending on pulmonary embolus location.     

1979 Memorial Award Paper. Comparison of exercise right ventricular performance in chronic obstructive pulmonary disease and coronary artery disease: noninvasive assessment by quantitative radionuclide angiocardiography.

The right ventricular (RV) response to upright bicycle exercise was assessed in 16 patients with chronic obstructive pulmonary disease (COPD), in 23 patients with coronary artery disease (CAD), and in 19 normal control subjects. Right ventricular (RV) and left ventricular (LV) ejection fractions were determined noninvasively using first-pass quantitative radionuclide angiocardiography, a technique well suited for simultaneous assessment of RV and LV systolic performance. The factors limiting exercise in COPD and CAD are distinctly different, and therefore patients with COPD were studied by means of a single-stage submaximal exercise test, while patients with CAD were studied by means of a graded maximal test. The normal response to exercise, irrespective of exercise protocol, was at least a 5% increase in RV and LV ejection fractions. In 12 of 16 patients with COPD, RV ejection fraction either decreased or remained the same with exercise (abnormal exercise RV reserve). Left ventricular exercise reserve was abnormal only in five patients, probably due to occult CAD. Isolated abnormal exercise RV reserve was present in nine patients. The severity of ventilatory impairment and resting arterial hypoxemia were major determinants of abnormal exercise RV reserve in patients with COPD. In 12 or 23 patients with CAD, RV ejection fraction either decreased or remained the same with exercise (abnormal exercise RV reserve). Left ventricular reserve was abnormal in 18 of 23 patients; RV exercise reserve was abnormal only in CAD patients with concomitant abnormal LV reserve. The presence of proximal right coronary artery stenosis (the major blood supply to the RV) was not a significant determinant of the RV response to exercise in patients with CAD. These data suggest that abnormal exercise RV reserve occurs frequently both in COPD and CAD patients. In COPD the predominant hemodynamic abnormality involves performance of the RV, while in CAD the predominant abnormality involves the LV. The common factor modulating RV exercise performance in both diseases appears to be altered RV afterload.     

Measurement of ventricular volumes and function: a comparison of gated PET and cardiovascular magnetic resonance.

The aim of this study was to compare cardiac volume and function assessment using PET with the reference technique of cardiovascular magnetic resonance (CMR). METHODS: Left ventricular (LV) and right ventricular (RV) end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), and ejection fractions (EF) were measured in 9 patients using both CMR and PET with inhaled C(15)O. RESULTS: Correlation between the techniques was generally reasonable (r values ranged from 0.63 to 0.99). Best agreement was seen for ESV (LV and RV). With PET, there was a tendency to underestimate LV EF and EDV, and RV EDV and SV. Agreement was worst for LV SV. Percentage difference between CMR and PET measurements ranged from -2% to 15%; Bland-Altman limits of agreement ranged from 24% to 75%. CONCLUSION: Although small systematic differences exist, the agreement between PET and CMR suggests useful information regarding function, and volumes may be obtained from a standard PET protocol.     

回顾性心电门控多层螺旋CT对急性肺栓塞右心室功能障碍及溶栓前后右心室功能变化的评价

目的 应用ECG门控MSCT前瞻性对中心型急性肺动脉栓塞(APE)患者右心功能障碍及静脉溶栓前后右心功能变化进行评价.方法 96名可疑APE患者进行了ECG门控MSCT胸痛三联检查,25例确诊为中心型肺栓塞.行胸痛三联检查无心肺疾患且性别、年龄匹配的25例作为对照组.APE患者于静脉溶栓后复查MSCT,评价右心功能恢复情况.测量参数包括横断面舒张期的右心室(RV)及左心室(LV)短轴最大内径,RV及LV舒张末期容积(EDV)、收缩末期容积(ESV)、射血分数(EF)、主肺动脉/主动脉直径比.应用单因素方差分析,如果有统计学意义,则采用两两组间q检验.结果 对照组的右心室EDV、ESV、EF值、收缩末期RV/LV容积比、横断面RV/LV内径比及主肺动脉/主动脉直径比分别为(15O.5±24.1)ml、(71.5±18.5)ml、(53.5±4.2)%、1.08±0.04、1.01±0.04及0.99±0.02,中心型APE患者溶栓前以上各值分别为(190.3±16.2)ml、(128.1±13.2)ml、(32.7±3.6)%、2.00±0.26、1.30±0.09及1.34±0.11,溶栓后分别为(159.2±21.5)ml、(80.7±9.4)ml、(49.2±5.9)%、1.22±0.25、1.02±0.02及1.02±0.11.中心型APE患者与对照组比较,右心室ESV(q=6.28,P<0.01)及EDV均增大(q=7.59,P<0.01),EF减小(q=4.82,P<0.01),收缩末期RV/LV容积比增大(q=6.04,P<0.01),横断面RV/LV内径比(q=4.43,P<0.01)及主肺动脉/主动脉直径比增大(q=4.36,P<0.01),左心室EDV减小.中心型APE患者静脉溶栓后,与溶栓前比较,右心室ESV(q=5.03,P<0.01)及EDV减小(q=6.11,P<0.01),EF增加(q=6.29,P<0.01),收缩末期RV/LV容积比减小(q=4.74,P<0.01),横断面RV/LV内径比(q=3.83,P<0.01)及主肺动脉/主动脉直径比减小(q=3.46,P<0.01),左心室EDV增大(q=4.01,P<0.01).结论 回顾性ECG门控MSCT胸痛三联检查可同时检测APE和测量左右心功能,排除其他胸痛疾病,评价溶栓疗效.     

Effects of spontaneous respiration on right and left ventricular function: evaluation by respiratory and ECG gated radionuclide ventriculography

To clarify the mechanism of inspiratory reduction of left ventricular (LV) stroke volume (SV) during spontaneous respiration, we measured right and left ventricular volume changes from expiration to inspiration using radionuclide ventriculography with respiratory gating technique. In this method, scintigraphic data were acquired in a list mode with ECG R wave triggers and respiratory volume curve derived from respiratory flowmeter. Cardiac cycles occurring during the second halves of inspiratory and expiratory phases were separately selected and used to produce multigated images for the respective phases. Twelve patients with normal LV ejection fraction (EF) (greater than 50%) and right ventricular (RV) EF (greater than 40%) and without pulmonary diseases were studied. LV end-diastolic volume (EDV) decreased during inspiration in all subjects (by 11 +/- 5%), whereas LV end-systolic volume (ESV) was insignificantly changed. Accordingly, LVSV decreased during inspiration in all subjects (by 17 +/- 7%). LVEF decreased from 64 +/- 6% during expiration to 60 +/- 6% during inspiration (p less than 0.001). In contrast to the left ventricle, RVEDV and RVSV increased during inspiration by 13 +/- 11% and 22 +/- 18%, respectively. RVESV did not change significantly. RVEF increased from 48 +/- 6% during expiration to 52 +/- 5% during inspiration (p less than 0.05). These results indicate that inspiratory reduction of LVSV during spontaneous respiration is due to a decrease in LVEDV which may be derived from an increase in RVEDV during inspiration through the mechanism of ventricular interdependence.     

Significance of increased right ventricular uptake on 99mTc-sestamibi SPECT in patients with coronary artery disease.

The significance of increased right ventricular (RV) tracer uptake in patients with coronary artery disease (CAD) without pulmonary or valvular heart disease is unclear. METHODS: Forty consecutive patients with increased RV uptake on SPECT myocardial perfusion imaging and right heart catheterization within 4 wk were studied prospectively. Thirty-five individuals with very low likelihood of CAD served as controls. Rest and stress SPECT myocardial perfusion data were obtained using a standard 99mTc-sestamibi 1-d imaging protocol. A quick and simple RV-to-left ventricular (LV) myocardial uptake ratio was calculated from the maximum counts per pixel detected in the right and left ventricles using the reconstructed coronal slices. RV end-systolic pressure (RV-ESP), mean pulmonary artery pressure (PAP) and pulmonary capillary wedge pressure were obtained by standard techniques. RESULTS: The RV/LV uptake ratio in the controls was 0.31+/-0.05. Thirty-six of the 40 (90%) CAD patients with increased RV tracer uptake had increased RV-ESP, and 39 (97.5%) had increased PAP. Highly significant positive correlations between the RV/LV uptake ratio and RV-ESP and PAP were found (r = 0.45, P = 0.003; and r = 0.52, P < 0.001, respectively). CONCLUSION: Increased RV uptake, assessed from standard myocardial perfusion studies, can identify RV pressure overload among patients with CAD. In the absence of pulmonary or valvular heart disease, increased RV uptake (i.e., RV pressure overload) indicates significant backward failure, a variable with known significant negative prognostic implications.     

Assessment of left ventricular diastolic function: comparison of contrast ventriculography and equilibrium radionuclide angiography.

Twenty-two patients with coronary artery disease were studied first by radionuclide angiography (RNA) and then by contrast ventriculography. Cardiac medications were discontinued at least 72 hr before study. The patients were studied during atrial pacing at heart rates close to their spontaneous sinus rhythm. Contrast ventriculography was performed at 50 frames/sec in the 30 degrees right anterior oblique projection using 40 ml of a nonionic contrast medium (iopamidol) at a flow rate of 10-12 ml/sec. The contours of the left ventricular silhouette at contrast ventriculography were traced, frame by frame, on a graphic table with a digitizing penlight. Equilibrium 99mTc RNA was performed in the best septal 45 degrees left anterior oblique projection, acquiring 150,000 cts/frame, at 50 frames/sec and with a 5% gate tolerance. Time-activity curves from both end-diastolic and end-systolic ROIs were built and interpolated. Both RNA and contrast ventriculography volume curves were filtered with Fourier five harmonics. A close relationship was found between RNA and contrast ventriculography measurements of peak filling rate normalized to end-diastolic cps (r = 0.87, p less than 0.001) and stroke count (r = 0.87, p less than 0.001), ejection fraction (r = 0.94, p less than 0.001). Thus, in patients with coronary artery disease, LV filling can be accurately assessed using RNA.     

Operator-interactive method for simultaneous measurement of left and right ventricular volumes and ejection fraction by tomographic electrocardiography-gated blood pool radionuclide ventriculography

BACKGROUND: A method that uses single photon emission computed tomography (SPECT) equilibrium radionuclide angiocardiography (ERNA) to measure right ventricular (RV) and left ventricular (LV) volumes (in milliliters) and ejection fraction (EF) is described. METHODS AND RESULTS: We recorded 35 paired SPECT ERNA and electron beam computed tomography (EBCT) cardiac studies in 27 patients; for comparison with EBCT, a method for measurement of RV and LV volumes and EF with SPECT ERNA was developed in 18 paired studies and was validated and assessed for reproducibility in 17. Validation indicated that SPECT ERNA and EBCT were similar for measurement of RV volume (end-systolic and end-diastolic volumes in a combined analysis) and EF (180+/-74 mL vs 182+/-80 mL and 0.44+/-0.11 vs 0.43+/-0.11, respectively) and for measurement of LV volume and EF (88+/-36 mL vs 84+/-43 mL and 0.53+/-0.081 vs 0.59+/-0.07, respectively). The SPECT ERNA method was quite reproducible. CONCLUSIONS: RV and LV volumes and EF can be measured readily via SPECT ERNA.