Assessment of cardiac function in patients with heart disease by quantitative gated myocardial perfusion SPECT

Objective We examined the cardiac function of patients who underwent Tc-99m sestamibi quantitative gated myocardial single photon emission computed tomography with 16-framing data acquisition between January 1, 2004 and March 31, 2006 for an evaluation of suspected or known heart disease in our hospital. Methods In 192 patients aged ≥40 years, the left ventricular (LV) systolic function [parameter: ejection fraction (EF)] and diastolic function [first third filling fraction (1/3FF), peak filling rate (PFR), and time-to-peak filling (TPF)] were estimated by volume curve analysis. In 51 (age ≥60 years) of 192 patients, brachial-ankle pulse wave velocity (baPWV) was also measured. Results The correlation between diastolic parameters PFR and 1/3FF was mild (r = 0.28, P < 0.001). On the basis of EF and PFR, 192 patients were divided into four groups: P (preserved LV function), Q (isolated systolic dysfunction, EF < 50%), R (isolated diastolic dysfunction, PFR < 1.8 EDV/s), and S (both dysfunctions). The numbers of patients in P, Q, R, and S groups were 94 (49.0%), 7 (3.6%), 31 (16.1%), and 60 (31.3%), respectively. The 1/3FF correlated weakly but significantly with age (r = −0.16, P < 0.05). The TPF also correlated weakly with age (r = 0.25, P < 0.01), but EF did not. The baPWV, an indicator of cardiovascular stiffness, correlated inversely with 1/3FF (r = −0.59, P < 0.001) or correlated positively with TPF (r = 0.45, P < 0.001), but not with EF. Conclusions Our study suggests that cardiovascular stiffness associated with increased baPWV may contribute to the occurrence of diastolic dysfunction in elderly patients.     

Benefits of quantitative gated SPECT in evaluation of perioperative cardiac risk in noncardiac surgery

Objective Gated single-photon emission computed tomography (G-SPECT) was used to evaluate cardiac risk associated with noncardiac surgery and determine the benefits and indications of this technique for this type of surgery. Materials and methods Patients scheduled to undergo noncardiac surgery under the supervision of anesthesiologists and subjected to preoperative cardiac evaluation using G-SPECT during the 26-month period between June 2000 and August 2002 were followed for the presence/absence of cardiac events (i.e., cardiac death, myocardial infarction, unstable angina, congestive heart failure, or fatal arrhythmia) during surgery and the postoperative period until discharged. Relationships between the occurrence of cardiac events and preoperative G-SPECT findings were evaluated. Results A total of 39 patients underwent G-SPECT; 6 of the 39 exhibited abnormal ejection fraction (left ventricular ejection fraction, LVEF ≤ 50%) and end-systolic volume (ESV ≥ 50 ml). Surgery was suspended for three of these six patients and cardiac events developed in the remaining three patients. Both abnormal perfusion images (PI) and abnormal wall thickening (WT) were observed in all six patients. All six patients exhibited abnormal LVEF and/or ESV. Three patients had either abnormal PI or WT, and a cardiac event occurred in one of them. Of the five patients who experienced cardiac events during or after surgery, two exhibited a short run of ventricular tachycardia requiring a continuous administering of antiarrhythmic drugs, whereas the remaining three patients exhibited cardiac failure requiring inotropic support following surgery. Conclusions The results of this study indicate that the occurrence of perioperative cardiac events can be predicted by considering the severity of expected surgical stress and preoperative G-SPECT findings for LVEF, PI, and WT. We conclude that G-SPECT is quite useful for cardiac risk assessment in patients undergoing noncardiac surgery.     

负荷心肌灌注显像与超声心动图对CAD患者的诊断和风险分级

负荷心肌灌注显像和负荷超声心动图是两种非侵入性诊断技术,对冠心病的诊断和风险分级具有重要价值,但两种技术均存在优势与不足。对冠心病的诊断,负荷心肌灌注显像比负荷超声心动图敏感性更高,但后者的特异性略高。在冠心病患者的风险分级方面,负荷心肌灌注显像比负荷超声心动图更有价值,如果负荷心肌灌注显像结果为阴性,即使冠脉造影证实为冠心病的患者,也提示为一个风险非常低的冠心病患者。     

Relationship between left ventricular function and wall motion synchrony in heart failure assessed by ECG-gated myocardial perfusion SPECT

Objective  To confirm the relationship between left ventricular (LV) function and wall motion synchrony, and to identify the difference of synchrony between an ischemic heart disease (IHD) patient group and other heart disease (OHD) patient group among classified groups in heart failure, systolic, and diastolic parameters were compared using electrocardiograph-gated single-photon emission computed tomography. Methods and results  Twenty IHD and 30 OHD patient groups, comprised New York Heart Association functional class I–III (IHD1-3 and OHD1-3), and 15 controls were examined. The LV functions (ejection fraction, EF; peak-filling rate, PFR) and synchrony, which was estimated from the time lag between the earliest and latest regional systolic or diastolic temporal parameters (maximum difference of regional time to end-systole, MD-TES, or maximum difference of regional time to peak filling, MD-TPF), were compared. The LV function correlated with its synchrony in IHD and OHD (EF vs. MD-TES: r = −0.86, P = 1.3 × 10⁻⁶ in IHD and r = −0.69, P = 2.8 × 10⁻⁵ in OHD. PFR versus MD-TPF: r = −0.67, P < 0.002 in IHD and r = −0.63, P < 0.0002 in OHD). Dyssynchronous normal EF was observed in three IHD (15%) and six OHD (20%). Dyssynchronous normal PFR was observed in six IHD (30%) and six OHD (20%). MD-TES was significantly smaller in control group (CG) than in IHD3 and OHD3 (P < 0.005), and in IHD1 than in IHD3 and OHD3 (P < 0.05). MD-TPF was significantly smaller in CG than in IHD2, IHD3, and OHD3 (P < 0.05). However, there was no significant difference between LV synchrony in IHD and OHD, or among LV synchrony of the same functional classes between these two groups. Conclusions  This study confirms that LV function is correlated with wall motion synchrony. No statistically significant difference was confirmed in wall motion synchrony between IHD and OHD. However, dyssynchrony appears in the patients without apparent global LV dysfunction. This feature may facilitate identification of synchronous disorder in HF patients with preserved global LV function. It is expected that detection of such a disorder may lead to the initiation of appropriate treatments for early stage HF and prevent its progression.     

Assessment of perfusion, function, and myocardial metabolism after infarction with a combination of low-dose dobutamine tetrofosmin gated SPECT perfusion scintigraphy and BMIPP SPECT imaging

BACKGROUND: Tetrofosmin gated single photon emission computed tomography (SPECT) allows simultaneous assessment of regional myocardial perfusion, global and regional left ventricular function, and function at rest and during pharmacologic intervention. SPECT with fatty acid analogues, such as beta-methyl-iodophenyl-pentadecanoic acid (BMIPP), can be used to monitor metabolic changes induced by myocardial ischemia. In this work, the results of both studies obtained in patients with recent myocardial infarction are integrated. METHODS: Twenty patients underwent tetrofosmin and BMIPP scintigraphy with a 3-head camera. Two consecutive tetrofosmin gated SPECT acquisitions were performed 60 minutes after administration of technetium-99m tetrofosmin (925 MBq) at rest (3x20 stops of 9 s; matrix 64x64 over 360 degrees . One acquisition was made at rest, and the second was made during dobutamine infusion (10 microg/kg/min). Regional functional abnormalities were quantified and expressed as wall thickening severity (WTsev) in arbitrary units. Left ventricular ejection fraction and volumes were assessed with the Cedars Sinai algorithm. BMIPP imaging started 20 minutes after iodine 123-BMIPP (150 MBq) administration at rest (3x32 stops of 60 s; matrix 64x64 over 360 degrees; medium energy collimators). Tracer uptake was scored according to a 25-segment model. RESULTS: Sixteen of 18 patients had regional functional abnormalities at baseline (average WTsev 13.7 units). The WTsev score at baseline correlated well with the degree of residual perfusion. During dobutamine infusion, WTsev did not change (from 23.4 to 23.6 units) in 5 patients; it decreased (from 16.1 to 5.9 units) in 11 patients; and it increased (from 13.0 to 22.3 units) in 3 patients. An increase or decrease in WTsev during dobutamine infusion was associated with the presence of a considerable amount of BMIPP mismatched myocardium, whereas no change in WTsev was preferentially associated with a BMIPP matched pattern and perfusion defects with a higher severity score. CONCLUSION: Immediately after infarction, the severity of regional dysfunction at rest correlated well with the perfusion defect severity. Improvement in regional function during dobutamine administration is associated with less severe perfusion defects and a considerable amount of BMIPP mismatched myocardium, both suggesting viability.     

Comparison of dobutamine stress echocardiography, dobutamine SPECT, and adenosine SPECT myocardial perfusion imaging in patients with end-stage renal disease

Objectives  We sought to assess and compare the diagnostic accuracy and prognostic value of dobutamine stress echocardiography (DSE), dobutamine SPECT, and adenosine SPECT myocardial perfusion imaging (MPI) in patients with end-stage renal disease (ESRD). Background  The optimal stress imaging modality for patients with ESRD has not yet been determined. Methods  Forty-nine patients with ESRD underwent DSE, dobutamine SPECT MPI, and adenosine SPECT MPI. The primary endpoint of the trial was concordance between stress tests with respect to the presence or absence of ischemia. Results  Agreement on the presence or absence of ischemia between adenosine SPECT MPI and DSE was 69% (kappa = .25, P = NS). Agreement on the presence or absence of ischemia between adenosine and dobutamine SPECT MPI was 77% (kappa = .37, P = <.009). Summed stress scores for adenosine and dobutamine SPECT MPI studies were highly correlated (r = .9, P = <.0001). DSE and SPECT MPI results provided incremental prognostic information when added to clinical variables. Conclusions  There is moderate concordance between DSE and adenosine SPECT MPI in ESRD patients referred for stress testing. Interobserver agreement was higher for SPECT MPI compared to DSE. Based on these observations, the optimal approach for diagnosing severe coronary artery disease and assessing risk in patients with ESRD has yet to be determined, but appears to warrant further investigation. Supported by grants from Hennepin Faculty Associates, the Minneapolis Medical Research Foundation, and DuPont Pharmaceuticals.     

Prognostic study of risk stratification among Japanese patients with ischemic heart disease using gated myocardial perfusion SPECT: J-ACCESS study

Background Although the prognostic value of myocardial perfusion imaging using gated single photon emission computed tomography (SPECT) for predicting major cardiac events has been evaluated, little is known about the relevance of this procedure to the Japanese population. Methods A total of 4,031 consecutive Japanese patients with suspected or confirmed ischemic heart diseases were registered at 117 hospitals in the Japanese Assessment of Cardiac Events and Survival Study by Quantitative Gated SPECT investigation. Gated stress/rest myocardial perfusion SPECT was performed and the patients were followed up for 3 years. Segmental perfusion scores and quantitative gated SPECT results were calculated. Major cardiac events were defined as cardiac death, nonfatal myocardial infarction, and severe heart failure. Results During the 3-year follow-up, cardiac death (n = 57) and nonfatal myocardial infarction (n = 39) occurred in 96 patients (2.4%/3 years) when hard events were the endpoints. When severe heart failure was included as an endpoint, major cardiac events that developed in 175 patients (4.3%/3 years) comprised cardiac death (n = 45), nonfatal myocardial infarction (n = 37), and severe heart failure (n = 93). Normal and severely abnormal summed stress score values were associated with low (2.31%/3 years) and high (9.21%/3 years) rates of major cardiac events, respectively. Rates of major cardiac events were significantly higher in patients with ejection fraction (EF) <45% than in those with EF 45% or higher (16.55 vs 2.94%/3 years; P < 0.001). The incidence of major cardiac events within 3 years was also significantly higher among patients with high end-systolic volumes. The major event rates were similar among nondiabetic patients with and diabetic patients without prior myocardial infarction at 5.06% and 5.73%/3 years, respectively. Conclusion Cardiac event rates were significantly lower in the Japanese than in the USA and European populations. However, large myocardial perfusion defects and decreased cardiac function, as well as diabetes mellitus, could be predictors of high event rates and, thus, beneficial for risk stratification of Japanese patients with ischemic heart diseases. Financial support: Japan Cardiovascular Research Foundation     

Risk stratification in patients with remote prior myocardial infarction using rest-stress myocardial perfusion spect: prognostic value and impact on referral to early catheterization

BACKGROUND: Little is known about the prognostic value of myocardial perfusion single photon emission computed tomography (SPECT) in patients with remote prior myocardial infarction (MI). METHODS AND RESULTS: We identified 1413 consecutive patients with remote prior MI who underwent rest-stress myocardial perfusion SPECT. Semiquantitative visual analysis of 20 SPECT segments was used to define the summed stress, rest, and difference scores. The number of non-reversible segments was used as an index of infarct size. During follow-up (>or=1 year), 118 hard events occurred: 64 cardiac deaths (CDs) and 54 recurrent MIs. Annual CD and hard event rates increased significantly as a function of SPECT abnormality. For summed stress scores less than 4, 4 to 8, 9 to 13, and more than 13, the annual CD rates were 0.4%, 0.9%, 1.7%, and 3.5%, respectively (P =.002). Patients with small MI (<4 non-reversible segments) and no or mild ischemia (summed difference score or=4 non-reversible segments) had moderate to high annual CD rates (3.7%-6.6%) regardless of the extent of ischemia. Nuclear testing added incremental prognostic information to pre-scan information. Compared with a strategy in which all patients are referred to catheterization, a strategy that referred only those patients with a risk for CD of greater than 1% by myocardial perfusion SPECT resulted in a 41.6% cost savings. CONCLUSIONS: Myocardial perfusion SPECT adds incremental value to pre-scan information and is highly predictive and cost-efficient in the risk stratification of patients with remote prior MI. Patients with normal or mildly abnormal scan results or small MI in combination with absent or mild ischemia have a low risk for CD.     

Nitrate-enhanced gated SPECT in patients with primary angioplasty for acute myocardial infarction: evidence of a reversible and nitrate-sensitive impairment of myocardial perfusion

Purpose Reperfusion of myocardial infarction (MI) leads to a reversible dysfunction of coronary vessels. We hypothesised that vasodilating drugs such as nitrates might improve sestamibi uptake within viable areas of recently reperfused MI, thereby enhancing prediction of subsequent improvements in perfusion and contractility. This study was aimed at assessing nitrate-enhanced sestamibi gated SPECT after MI reperfusion. Methods Twenty-nine patients underwent rest followed by nitrate sestamibi gated SPECT at 9 ± 3 days after primary angioplasty for acute MI and at follow-up, 4–10 months later. Four MBq/kg of ^99mTc-sestamibi was injected at rest, and 12 MBq/kg after nitroglycerin spray. Results Follow-up improvements were documented for both perfusion (P+) and contractility (C+) in 18% of the 180 initially abnormal segments, in neither perfusion (P−) nor contractility (C−) in 44%, in contractility only (C+P−) in 16% and in perfusion only (C−P+) in 22%. Perfusion improvement was related to lower sestamibi uptake on baseline rest SPECT (P+: 42 ± 15% vs P−: 50 ± 15%, p = 0.001) and, moreover, to a higher increase between rest and nitrate uptake (P+: +9.5 ± 6.5% vs P−: +2.0 ± 5.9%, p < 0.001). Contractility improvement was related to sestamibi uptake on baseline nitrate SPECT (C+: 58 ± 15% vs C−: 38 ± 16%, p < 0.001), a variable enhancing the prediction provided by sestamibi uptake at rest (p < 0.05). Conclusion The improvement in perfusion which is documented in the months following MI reperfusion is predicted by initial nitrate enhancement of sestamibi uptake, suggesting a mechanism of reversible vascular injury. In this particular setting, sestamibi uptake is a better predictor of contractility recovery when determined after nitrate administration rather than under conventional resting conditions.     

门控心肌灌注断层显像评价扩张型心肌病患者左室同步性的价值

目的：本研究主要探讨门控心肌灌注显像诊断扩张型心肌病患者左心室收缩不同步的价值。方法选取在本院接受核素心肌灌注显像的扩心病患者共47例,根据心电图Q RS波时限分为Q RS波正常组（20例）和Q RS波增宽组（27例）;选取同时期35例正常受检者作为正常对照组。入选对象行99m Tc‐MIBI心肌灌注显像,观察门控数据,计算不同步指数（AI）以及左室射血分数（EF）、舒张末容积（EDV ）、收缩末容积（ESV ）等。运用方差分析比较各组间指标,运用秩和检验AI差异,以 P＜0．05作为差异具有统计学意义。结果三组EF之间均存在显著差异（ P＜0．001）;QRS增宽组13例为间隔‐侧壁收缩延迟,7例为前壁‐后壁收缩延迟,A I在2～5之间,Q RS波正常组中有2例存在间隔‐侧壁收缩延迟,AI分别为2、3,两组AI差异具有统计学意义（ P ＝0．03）。结论该方法能够直观了解左心室各壁运动的协调性,判断左室收缩延迟的具体部位和延迟程度,对左室不同步的诊断和治疗具有一定价值。     

门控断层显像在心肌灌注断层显像中的应用

使用门控心肌断层显像不但减低了心脏搏动产生的图像边缘模糊,提高了对心肌缺血诊断的灵敏度和特异性,而且通过傅立叶变换和图像边缘识别技术等图像处理技术,可以在一次采集的信息基础上同时获得心脏的心肌血流灌注、心肌活力、室壁运动、射血功能和收缩协调性等参数,提高了核素心脏检查的价值,为临床准确判断患者的心脏状况,选择治疗方案,预后及疗效评价提供了更可靠的数据。本文就其近年来的临床应用进行综述。     

慢性稳定型冠心病的核素心肌灌注显像临床应用进展

多项临床试验证明,核素心肌灌注显像在冠心病诊断、危险度分层、预后判断、病人处理方案等方面具有突出的作用和优越的价值。在ACC/AHA(美国心脏病学院/美国心脏学会)有关冠心病和核心脏病学指南中,心肌灌注显像的上述作用得到了充分肯定。合理应用该项技术可以提高对冠心病诊断、处理的整体水平,并使有限的医疗资源得到更合理利用,这在我国目前显得十分迫切和需要。     

99Tcm-NOET门控心肌灌注SPECT评价冠心病的价值

目的评价99Tcm--双（N-乙氧基,N-乙基-二硫代氨基甲酸酯）氮化锝（99Tcm-NOET）静息门控断层心肌灌注显像对冠心病患者的诊断价值。方法疑诊为冠心病的45例患者注射925MBq 99Tcm-NOET后1h用SPECT行静息门控心肌灌注显像,获得舒张未期容积（EDV）、收缩未期容积（ESV）、左室射血分数（LVEF）等心功能参数和舒张末期容积灌注、局部射血分数、局部室壁活动和室壁增厚度4个靶心图。所有患者在1周内行冠状动脉造影,将冠状动脉狭窄≥50％定为病变血管。根据冠状动脉造影结果将其分为心肌梗死组、心肌缺血组和对照组三组。结果99Tcm-NOET静息门控SPECT诊断冠心病的灵敏度和特异度分别为68．42％和83．33％。心肌梗死组的心功能参数[EDV=（129．32±9．14）ml,ESV=（80．97±9．49）ml,LVEF=（40．15±3．28）％】与对照组【EDV=（80．91±3．12）ml,ESV=（30．12±1．79）ml,LVEF=（63．51±1．04）％]相比,统计学差异有显著性（EDV：F=22．103,ESV：F=32．277,LVEF：F=42．60：4,均为P〈0．01）,心肌缺血组的心功能参数[（EDV=（70．83±3．46）ml,ESV=（25．13±2．85）ml,LVEF=（65．55±2．62）％1与对照组相比,统计学差异无显著性意义。心肌梗死组左室心肌共分为460个节段,其中209个节段局部灌注、局部射血分数、局部室壁活动和室壁增厚度4个靶心图均异常。局部灌注异常的节段共328个节段,伴有局部射血分数、局部室壁活动和室壁增厚度异常分别有250个、240个和276个节段。局部灌注异常的节段与局部射血分数、局部室壁活动和室壁增厚度异常的节段不完全匹配。结论99Tcm-NOET静息门控心肌灌注显像对冠心病的诊断有较大临床应用价值,所获得的整体心室功能参数在心肌梗死的评价中有优越性,但对心肌缺血的诊断价值不大。心肌梗死中存在有不少的局部灌注与心肌?     

Myocardial perfusion SPECT imaging in patients with myocardial bridging

BACKGROUND: Although myocardial perfusion single photon emission computed tomography (SPECT) imaging is widely used to assess myocardial ischemia in patients with known or suspected coronary artery disease, only a few patients with myocardial bridging have been evaluated with nuclear techniques. Furthermore, it has been suggested that dipyridamole stress images might underestimate perfusion defects compared with exercise stress images. This study was done to determine the concordance of exercise stress SPECT images with that obtained by dipyridamole stress SPECT images as a means of detecting ischemia in patients with myocardial bridging. METHODS AND RESULTS: Sixteen consecutive patients with angina and normal arteries but myocardial bridging of the left anterior descending artery underwent rest-exercise stress SPECT imaging. Within 2 weeks after angiograms were obtained, only dipyridamole stress images were repeated. The mean angiographic systolic occlusion within the myocardial bridges was 73% +/- 10%. Overall, the prevalence of an abnormal scan was no different in patients who underwent exercise stress myocardial perfusion imaging (MPI) as compared with patients who underwent dipyridamole stress MPI (14/16 [88%] vs 13/16 [81%], respectively; P = .953). Exercise stress MPI showed a higher stress score than dipyridamole stress MPI, but the difference did not reach statistical significance (7.5 +/- 3.3 vs 6 +/- 2.7, P = .147). The strength of agreement among exercise stress MPI and dipyridamole stress MPI studies was good (kappa = 0.765; 95% CI, 0.318 to 1.211; P < .05). CONCLUSIONS: Cardiac SPECT studies can be used effectively for assessing ischemia in patients with angina and myocardial bridging. The evaluation of myocardial perfusion with dipyridamole stress SPECT imaging showed a good agreement with exercise stress SPECT imaging for the detection of ischemia in this group of patients.     

Prognostic value of quantitative stress myocardial perfusion imaging in unstable angina patients with negative cardiac enzymes and no new ischemic ECG changes

Background. Limited data are available on the value of quantitative stress myocardial perfusion imaging (MPI) in patients with unstable angina. In this report we sought to study the long-term prognostic value of quantitative stress MPI in patients hospitalized with unstable angina with no new ischemic electrocardiographic changes and negative cardiac enzymes. Methods and Results. The study population consisted of 136 patients who were hospitalized at the Methodist Hospital, Houston, Tex, with unstable angina and subsequently underwent MPI before discharge. Cox proportional hazards (regression) analysis was performed to identify clinical and MPI predictors of hard cardiac events (death or nonfatal myocardial infarction). During a mean follow-up of 31 ± 17 months, 20 patients (15%) sustained either cardiac death (n = 12) or nonfatal myocardial infarction (n = 8). The significant multivariate predictors of cardiac events were the total perfusion defect size (P = .002), the presence of reversible perfusion defects (P = .01), and the presence of multiple perfusion defects (P = .03). The perfusion defect size was significantly larger in patients with events than in those without events (21% ±20% vs 12% ± 14%, P = .002). Kaplan-Meier analysis showed that cardiac events were much more likely to develop in patients with defects involving 15% or more of the left ventricle than in those with defects involving less than 15% of the left ventricle (P = .003). Conclusions. In patients hospitalized with unstable angina with no new ischemic electrocardiographic changes and negative cardiac enzymes, quantitative stress MPI provides powerful prognostic information that can be used in the risk stratification of these patients. (J Nucl Cardiol 2005;12:32-6.)     

Gated SPECT in patients with hypertrophic obstructive cardiomyopathy undergoing transcoronary ethanol septal ablation

BACKGROUND: Transcoronary ethanol septal ablation (TESA) is a novel treatment for obstructive hypertrophic cardiomyopathy (HOCM). Our objective was to evaluate the use of gated single photon emission computed tomography (SPECT) in patients with HOCM and the effects of TESA on myocardial perfusion. METHODS AND RESULTS: We performed gated SPECT and Doppler echocardiography before and 6 weeks after TESA in 30 patients with severe HOCM. The lung-to-heart and septal-to-lateral wall count-activity ratios were calculated. Before ablation, SPECT showed perfusion abnormalities in only 6 patients. Asymmetric septal hypertrophy was noted in 21 patients (70%). In patients with a lung-to-heart ratio greater than 0.50 before ablation, the ratio decreased from 0.56 +/- 0.04 to 0.45 +/- 0.08 after ablation (P <.01). The septal-to-lateral wall ratio also decreased significantly after ablation. Mean Doppler pressure gradient across the left ventricular outflow tract decreased from 52 +/- 39 mm Hg to 13 +/- 13 mm Hg (P <.01) immediately after ablation and to 10 +/- 21 mm Hg 6 weeks later (P <.01). There were no significant changes in left ventricular ejection fraction by gated SPECT after the procedure. SPECT studies done after ablation showed fixed septal defects in 29 of 30 patients (96.7%). The defects involved the basal and mid septum in 100% and 38% of patients, respectively, and ranged in size from 2% to 30% of the left ventricle (mean, 8.8% +/- 7.0%). CONCLUSIONS: TESA is an effective technique for relieving left ventricular outflow obstruction in patients with HOCM. Myocardial gated SPECT can identify the presence and location of infarction after TESA.     

门控心肌灌注显像时相分析在心脏再同步化治疗中的应用

门控心肌灌注显像(GMPI)的时相分析技术评价左室机械不同步性前景看好,该方法的优点在于自动控制处理、重复性良好,并能得到灌注和预后信息。该文综述时相分析技术及其GMPI在心脏再同步化治疗中的应用价值。     

Development of a method for measuring myocardial contractility with gated myocardial SPECT and arterial tonometry

BACKGROUND: Gated myocardial single photon emission computed tomography (SPECT) and radial artery applanation tonometry were used, respectively, to quantify the time-volume curve of the left ventricle and to estimate ventricular pressure wave. We developed ways of determining end-systolic elastance (Ees) with the normalized-single-beat method and tested the reproducibility of these measurements. METHODS AND RESULTS: In patients with coronary artery disease (male/female = 33:2, age 66 +/- 10 years, ejection fraction 22% to 77%), rest thallium-201 gated/poststress technetium-99m sestamibi gated SPECT/24-hour rest Tc-99m sestamibi gated SPECT and arterial tonometry were performed. Quantitative gated SPECT software yielded a systolic time-volume curve, and tonometrically measured radial artery pressure wave yielded central aortic pressure wave. With systolic half of pressure-volume curve, void volume (Vo) was estimated and Ees was calculated. Over 71 measurements Ees ranged from 1.7 to 5.3 and Vo from -4 to 200 mL. Ejection duration, other indexes of central pressure waveform, end-diastolic volume, end-systolic volume, and ejection fraction were reproducible. The reproducibility of Vo was excellent (r = 0.97). Ees at rest (n = 15) showed fair reproducibility between Tc-99m-sestamibi and TI-201 SPECT (r = 0.51). CONCLUSION: With gated myocardial SPECT, a noninvasive method of quantifying myocardial global contractility was developed. Reproducibility of this measurement was sufficient for use in clinical routine. Ees measured by this method warrants validation by invasively measured Ees.     

Risk stratification of patients with prior myocardial infarction and advanced left ventricular dysfunction by gated myocardial perfusion SPECT imaging

Background. The Multicenter Automatic Defibrillator Implantation Trial II (MADIT-II) has shown that the prophylactic implantable cardiac defibrillator improves the survival rate of patients with prior myocardial infarction and advanced left ventricular (LV) dysfunction. However, a more accurate noninvasive predictor should be found to identify subgroups at high risk, one that would allow implantable cardiac defibrillator therapy to be directed specifically to the patients who would benefit most. Methods and Results. To elucidate whether technetium 99m tetrofosmin electrocardiogram-gated single photon emission computed tomography (SPECT) imaging at rest can determine the risk of arrhythmic death, 106 patients who met the MADIT-II criteria (LV ejection fraction ≤0.3, myocardial infarction τ;1 month earlier, and no sustained ventricular tachyarrhythmia) were recruited from a pool of 4628 consecutive patients who had undergone resting Tc-99m tetrofosmin SPECT imaging. By use of the endpoints of lethal arrhythmic events, which included documentation of sustained ventricular tachycardia, ventricular fibrillation, or diagnosis of sudden cardiac death, we performed follow-up for a mean of 30 months. Lethal arrhythmic events occurred in 14 patients. Patients with lethal arrhythmic events had a lower LV ejection fraction, greater LV end-systolic and end-diastolic volume indices, and a greater perfusion defect volume than the remaining patients. By receiver operating characteristic curve analysis, myocardial defect volume was the strongest predictor for the development of lethal arrhythmic events. Conclusion. Our results confirm that perfusion defect volume by Tc-99m tetrofosmin scintigraphy is the most pivotal predictor of the future occurrence of lethal arrhythmic events and of sudden cardiac death. Tc-99m tetrofosmin SPECT images may assist in identifying subsets of patients with a greater likelihood of arrhythmic death among patients with LV dysfunction.     

SPECT myocardial perfusion imaging with prone-only acquisitions: correlation with coronary angiography

Background  Recent evidence suggests that combining supine and prone acquisitions during stress-gated SPECT myocardial perfusion imaging (MPS) improves detection of obstructive coronary artery disease (CAD), though the additional imaging time required may not be feasible in routine clinical practice. MPS with prone-only acquisitions is occasionally performed in many laboratories, though little is known about the ability of modern MPS with prone-only acquisitions to detect obstructive CAD. Our goal was to assess the ability of MPS with prone-only acquisitions to detect obstructive CAD as determined by coronary angiography. Methods and Results  We studied 386 patients referred for MPS with either recent coronary angiography or a low pretest likelihood of coronary artery disease. All rest and stress images were obtained exclusively in the prone position. The sensitivity of prone-only MPS was 88% for detecting ≥50% coronary artery stenosis and 92% for detecting ≥70% coronary artery stenosis as determined by coronary angiography. Normalcy rate for prone-only MPS in patients with low probability for CAD was 95%, and normalcy rates did not significantly differ among coronary artery distributions. Conclusions  The findings of this study suggest that MPS using prone-only acquisitions is a reasonable diagnostic option for the detection of ischemia due to obstructive coronary artery disease.