Clinical evaluation of no-carrier-added meta-[123I]iodobenzylguanidine for myocardial scintigraphy

In clinical and research studies, images obtained using carrier-added meta-[¹²³I]iodobenzylguanidine (c.a. [¹²³I]MIBG) have shown quite variable quality, with varying levels of uptake in lung, liver and mediastinum; this is a significant problem for quantification of the myocardial uptake by means of region ratios. First experimental and preliminary human data in respect of no-carrier-added (n.c.a.) [¹²³I]MIBG are indicative of improved imaging quality. The aim of the present study was to evaluate the clinical value of myocardial scintigraphy with n.c.a. [¹²³I]MIBG in patients with tachyarrhythmias. The study population comprised 24 patients with tachyarrhythmogenic diseases routinely studied by cardiac single-photon emission tomography (SPET) with [¹²³I]MIBG. Twelve of the 24 patients were studied with c.a. [¹²³I]MIBG (seven females and five males; mean age 42±13 years, range 20–60 years), whereas the other 12 were studied with n.c.a. [¹²³I]MIBG (ten females, two males; mean age 41±11 years, range 18–60 years, P=NS). For quantification of the specific uptake in the different organs, count ratios were calculated on SPET images acquired 4 h p.i. Visual analysis of all [¹²³I]MIBG scans showed improved image quality (improved contrast between heart and neighbouring organs) in n.c.a. studies as compared with c.a. studies. A significantly higher heart/left atrial blood ratio was found in the n.c.a. studies as compared with the c.a. studies (10.3±3.2 vs 5.3±1.3, P=0.0003); furthermore, significantly higher heart/lung and heart/liver ratios (2.5±0.6 vs 1.5±0.3, P=0.0002, and 0.8±0.2 vs 0.6±0.1, P=0.0006, respectively) were obtained in the c.a. studies, whereas lung/left atrial blood and liver/left atrial blood ratios showed no significant differences (4.2±1.3 vs 3.6±1.1, P=0.39, and 13.7±5.2 vs 9.6±2.2, P=0.21, respectively). In conclusion, the use of n.c.a. [¹²³I]MIBG yields a significantly higher myocardial uptake associated with improvement in contrast between the heart and neighbouring organs and is therefore superior to the commercially available c.a. [¹²³I]MIBG for use in clinical and research studies of the myocardial presynaptic sympathetic nervous system. Furthermore, our data indicate that for quantification the use of a left atrial blood reference region of interest, which is only available on SPET studies, is to be recommended. Received 22 September and in revised form 2 November 1999     

美托洛尔与胺碘酮联合治疗98例快速性心律失常的效果观察

目的观察美托洛尔联合胺碘酮治疗快速心律失常的临床疗效。方法选取快速心律失常患者196例,按照数字随机表法将其分为对照组和观察组。每组98例。对照组患者采用胺碘酮治疗,观察组患者在对照组治疗基础上再予以美托洛尔治疗。比较两组患者的临床疗效。结果观察组患者治疗总有效率明显高于对照组患者,组间比较差异具有显著性(P<0.05),两组患者不良反应发生率无明显差异(P>0.05)。结论美托洛尔联合胺碘酮治疗快速心律失常具有安全、疗效确切的优点,具有一定的临床价值。     

胺碘酮联合美托洛尔静脉注射治疗快速心律失常的临床观察

目的：对胺碘酮联合美托洛尔静脉注射应用于快速心律失常的效果加以分析。方法：随机选择本院2010年5月-2012年5月快速心律失常患者86例为研究对象,分成治疗组和对照组,治疗组53例患者给予胺碘酮联合美托洛尔医治;对照组33例患者给予美托洛尔药物医治。结果：经治疗,治疗组患者心电图显示早搏改善效果优于对照组,有效率高于对照组,但不良反应发生率低于对照组,两组比较差异均有统计学意义（P<0.05）。结论：胺碘酮联合美托洛尔静脉注射应用于快速心律失常,有效率较高。     

Systemic inflammatory changes after pulmonary vein radiofrequency ablation do not alter stem cell mobilization

Aims: Aim of this study was to investigate the number of circulatingprogenitor cells, systemic inflammatory mediators, and myocardialnecrosis in patients with paroxysmal atrial fibrillation (AF)undergoing pulmonary vein (PV) isolation by radiofrequency (RF)ablation. Radiofrequency ablation generates a localized myocardialnecrosis that might result in a release of inflammatory mediatorsenhancing progenitor cell mobilization and improving tissuerepair. Methods and results: Blood samples were collected in patients with paroxysmal AFbefore and after PV isolation. Interleukin (IL)-6, IL-1β,TNF-, IL-8, IL-10, and IL-12, and stromal derived factor (SDF)-1were measured by immunoassay. CD34+CD133+, CD117+, and endothelialprogenitor cells (EPCs) were analysed by flow cytometry andculture assay. After ablation procedure, a rise in creatinekinase and troponin T levels indicated myocardial necrosis.Leukocyte counts and C-reactive protein and IL-6 levels increasedsignificantly. Myocardial necrosis and inflammatory responsecorrelated with an increase in IL-6 (P = 0.007). In contrast,SDF-1 levels decreased after RF ablation (P = 0.004). Yet, nosignificant changes were observed in IL-1β, TNF-, IL-8,IL 10, and IL-12 plasma levels or in the number of circulatingCD34+CD133+ and CD117+ progenitor cells, whereas EPCs decreasedby trend. Conclusion: Although PV isolation by RF ablation in patients with paroxysmalAF induces a systemic inflammatory response associated withmyocardial necrosis, no alterations in circulating progenitorcells were observed. Thus, isolated myocardial necrosis maynot be sufficient to account for progenitor cell mobilization.     

Hypokalemia during the cooling phase of therapeutic hypothermia and its impact on arrhythmogenesis

Background

Mild to moderate therapeutic hypothermia (TH) has been shown to improve survival and neurological outcome in patients resuscitated from out-of-hospital cardiac arrest (OHCA) with ventricular fibrillation (VF) as the presenting rhythm. This approach entails the management of physiological variables which fall outside the realm of conventional critical cardiac care. Management of serum potassium fluxes remains pivotal in the avoidance of lethal ventricular arrhythmia.

Methods

We retrospectively analyzed potassium variability with TH and performed correlative analysis of QT intervals and the incidence of ventricular arrhythmia.

Results

We enrolled 94 sequential patients with OHCA, and serum potassium was followed intensively. The average initial potassium value was 3.9 ± 0.7 mmol l⁻¹ and decreased to a nadir of 3.2 ± 0.7 mmol l⁻¹ at 10 h after initiation of cooling (p < 0.001). Eleven patients developed sustained polymorphic ventricular tachycardia (PVT) with eight of these occurring during the cooling phase. The corrected QT interval prolonged in relation to the development of hypothermia (p < 0.001). Hypokalemia was significantly associated with the development of PVT (p = 0.002), with this arrhythmia being most likely to develop in patients with serum potassium values of less than 2.5 mmol l⁻¹ (p = 0.002). Rebound hyperkalemia did not reach concerning levels (maximum 4.26 ± 0.8 mmol l⁻¹ at 40 h) and was not associated with the occurrence of ventricular arrhythmia. Furthermore, repletion of serum potassium did not correlate with the development of ventricular arrhythmia.

Conclusions

Therapeutic hypothermia is associated with a significant decline in serum potassium during cooling. Hypothermic core temperatures do not appear to protect against ventricular arrhythmia in the context of severe hypokalemia and cautious supplementation to maintain potassium at 3.0 mmol l⁻¹ appears to be both safe and effective.     

Wearable cardioverter defibrillator: A life vest till the life boat (ICD) arrives

It is well established that implantable cardioverter defibrillator (ICD) is a life saving device ensuring protection against life threatening ventricular arrhythmias. But there are certain situations like a recent myocardial infarction where the standard guidelines do not recommend the implantation of an ICD while the patient can still be at a risk of demise due to a life threatening ventricular arrhythmia. There could also be a temporary indication for protection while explanting an infected ICD system. The wearable cardioverter defibrillator (WCD) is a device which comes to the rescue in such situations. In this brief review, we discuss the historical aspects of the development of a WCD, technical aspects as well as the clinical trial data and real world scenario of its use.     

Detection of T-wave alternans using an implantable cardioverter-defibrillator

BACKGROUND: Microvolt T-wave alternans (TWA) increases acutely prior to ventricular tachycardia (VT) or ventricular fibrillation (VF) in computer simulations and animal models, suggesting that TWA may provide a warning for VT/VF in patients with an implantable cardioverter-defibrillator (ICD). OBJECTIVES: The purposes of this study were to develop a method for analyzing TWA recorded from ICD electrograms (EGMs) and to evaluate the degree of concordance between EGM TWA and TWA recorded from the surface ECG. METHODS: We developed a software program to measure EGM TWA in the frequency domain and then used simulated EGMs to determine the effects of ICD signal processing, electrical noise, and variation in the EGM fiducial point on the recorded amplitude and K score (signal-to-noise ratio) of TWA. We then applied this method to analyze TWA simultaneously using both surface ECGs and ICD EGMs during incremental pacing in 25 ICD patients. Pacing modes and EGM sources were varied in repeated trials. EGMs with dynamic range adjusted to achieve a large T wave were telemetered to a digital Holter recorder and measured offline. ECG TWA was analyzed using a commercial system. A positive (+) ECG test had sustained alternans >or=1.9 microV with K score >or=3. Stored EGMs were reviewed for VT/VF during a 6-month follow-up period. RESULTS: Simulations demonstrated that the EGM method accurately identified TWA >or=10 microV. Overall, 10 (40%) patients had at least one ECG TWA+ test and 15 patients (60%) had no ECG TWA+ tests. The maximum value of TWA was greater in EGMs than in ECGs (median 64 microV vs 2.2 microV, P <.0001). EGM TWA was greater in ECG TWA+ tests than in ECG TWA- tests (169 +/- 175 microV vs 71 +/- 61 microV, P <.001). Using a sustained EGM TWA threshold of 30 microV, EGM TWA was concordant with ECG TWA in 63 (84%) of 75 analyzed tests (P <.0001) and predicted ECG TWA results with 85% sensitivity and 84% specificity. Both ECG and EGM TWA predicted VT/VF during follow-up (ECG: P = .006; EGM: P = .035). CONCLUSION: The amplitude of TWA is at least 10 times greater on ICD EGMs than on surface ECGs. EGM and ECG TWA have substantial concordance and comparable predictive value for spontaneous VT/VF. These observations support the hypothesis that ECG and EGM TWA detect the same electrical alternans phenomenon.     

胺碘酮在院前心肺复苏中的应用

目的探讨胺碘酮在心肺复苏过程中出现的快速性心律失常患者中的疗效。方法将158例心肺复苏过程中出现快速性心律失常患者随机分成3组,分别用利多卡因（53例）、胺碘酮（55例）、利多卡因联合胺碘酮（50例）治疗,比较其疗效。结果利多卡因组总有效率54．72％,胺碘酮组总有效率81．82％,利多卡因联合胺碘酮总有效率76％,胺碘酮组及利多卡因联合胺碘酮组与利多卡因组比较,差异有显著性意义。结论胺碘酮对心肺复苏过程中出现的快速性心律失常患者有比较好的疗效。