Intrathoracic and Ventricular Impedances are Associated with Changes in Ventricular Volume in Patients Receiving Defibrillators for CRT

Background: Some implantable cardioverter defibrillators (ICD) are able to monitor intrathoracic impedance to detect pulmonary fluid overload. This is achieved by measuring impedance between the ICD case and the right ventricular (RV) lead. We hypothesized that the measured impedance would rise with improvement in left ventricular (LV) volumes during cardiac resynchronization therapy (CRT), and that such impedance changes would be more apparent when measured with an alternative pacing vector.
Methods: We analyzed echocardiographic and impedance data from heart failure patients implanted with a CRT–ICD capable of intrathoracic impedance measurement for fluid accumulation diagnosis, and LV pacing impedance recording for lead integrity monitoring.
Results: In 127 out of 170 patients that received de novo CRT implantation, the LV end-systolic volume (LVESV) decreased at 6-month follow-up (LVESV at 6 month—LVESV at baseline <0: group A). For the remaining 43 patients (group B) the change was ≥0. Despite comparable values at baseline (P = 0.262), the impedances of groups A and B gradually diverged soon after the implant, resulting in significant difference between the two groups at the 6-month visit (P = 0.001). The changes in LV dimensions produced larger differences between groups in the impedance measured between the LV and the RV leads (P < 0.001). The regression analysis demonstrated an inverse correlation between paired changes of volume and intrathoracic impedance. Higher correlation coefficient was obtained using the LV-to-RV measurement vector (r =−0.635, P < 0.001).
Conclusions: The changes in ICD-measured impedance seem associated with the LV volume changes induced by CRT. Specifically, the LV-to-RV impedance estimations seem to better correlate with paired changes of ventricular volumes. (PACE 2010; 64–73)     

实时三维超声心动图评价左室重构心功能的初步探讨

目的探讨实时三维超声心动图(RT-3DE)评价重构左室收缩功能的方法及可行性. 方法对26例不同病因所致左室形态重构的患者,应用RT-3DE采集左室腔立体数据库,测量左室舒张末期容积(EDV)、收缩末期容积(ESV)和左室射血分数(LVEF).同时应用二维超声(2DE)双平面Simpson's法和M型(ME)Teichholz法分别测量左室EF值.在心尖四腔、三腔和两腔心切面上,用ME记录二尖瓣瓣环在后间隔、侧壁、后壁、前间隔、下壁、前壁六个位点上运动的平均距离.分别比较RT-3DE与2DE、ME测值的相关性. 结果 RT-3DE能显示完整左室腔的立体形态.RT-3DE测定的LVEF值与二尖瓣瓣环运动的平均距离之间有很好的相关性(r＝0.9045,P<0.001),与二维法及M型法测量值之间相关性较低(r＝0.7355,r＝0.7218,P<0.01). 结论 RT-3DE为定量分析左室容积和收缩功能提供了一种无创的,准确可信的新途径.     

Marked Improvement in Left Ventricular Function and Significant Reverse Left Ventricular Remodeling within 3 Months of Cardiac Resynchronization Therapy in Patients with Dilated Cardiomyopathy

We monitored reverse left ventricular (LV) remodeling and LV function during the first 6 months of cardiac resynchronization therapy (CRT) in 34 patients (mean age = 55.3 ± 13.6 years, 28 men) with dilated cardiomyopathy (DCM), left bundle branch block, in stable New York Heart Association class III, and on fixed drug regimen who underwent implantation of CRT systems with or without cardioverter defibrillator back-up. QRS-complex duration was reduced from 169.69 ± 19.6 ms (SD) to 144.1 ± 23.4 ms during CRT. Parasternal M-mode and apical 2D-echocardiography was performed before and 3 and 6 months after device implantation. LV enddiastolic (EDD) and endsystolic (ESD) diameters were measured, and biplane LV enddiastolic (EDV), and endsystolic (ESV) volumes and ejection fractions (EF) were calculated using a modified Simpson formula. Significant decreases in LVEDD (P = 0.0064 at 3 months and P = 0.021 at 6 months), LVESD (P = 0.023 at 3 months, and P = 0.003 at 6 months), and LVESV (P = 0.006 resp. P = 0.007), and increases in LVEF (P = 0.003 at 3 months and P < 0.001 at 6 months) were observed. Mean LVEF increased from 23% at baseline to 39% at 6 months. CRT induced prominent reverse LV remodeling and significantly increased LVEF within a few months in patients with DCM.     

Left Ventricular Mechanical Assist Devices and Cardiac Device Interactions: An Observational Case Series

Background: Nonpulsatile left ventricular assist devices (LVADs) are increasingly used for treatment of refractory heart failure. A majority of such patients have implanted cardiac devices, namely implantable cardioverter-defibrillators (ICDs) or cardiac resynchronization therapy-pacemaker (CRT-P) or cardiac resynchronization therapy-defibrillator (CRT-D) devices. However, potential interactions between LVADs and cardiac devices in this category of patients remain unknown.
Methods: We reviewed case records and device logs of 15 patients with ICDs or CRT-P or CRT-D devices who subsequently had implantation of a VentrAssist LVAD (Ventracor Ltd., Chatswood, Australia) as destination therapy or bridge to heart transplantation. Pacemaker and ICD lead parameters before and after LVAD implant were compared. In addition, ventricular tachyarrhythmia event logs and potential electromagnetic interference reports were evaluated.
Results: Right ventricular (RV) sensing decreased in the first 6 months post-LVAD. Mean R-wave amplitude preimplant was 10.9 ± 5.25 mV compared with 7.2 ± 3.4 mV during follow-up (P = 0.02). RV impedance also decreased from 642 ± 240 ohms at baseline to 580 ± 212 ohms at follow-up (P = 0.007). There was a significant increase in RV stimulation threshold following implantation of the LVAD from 0.8 ± 0.6 V at baseline to 1.4 ± 1.0 V in the first 6 months postimplant (P = 0.01). A marked increase in ventricular tachyarrhythmia burden was observed in three patients. One patient displayed electromagnetic interference between the LVAD and defibrillator, resulting in inappropriate defibrillation therapy.
Conclusions: LVADs have a definite impact on cardiac devices in respect with alteration of lead parameters, ventricular tachyarrhythmias, and electromagnetic interference.     

Cardiac Resynchronization Therapy in Patients with Right Ventricular Pacing-Induced Cardiomyopathy

Background: It is not known whether patients with normal baseline left ventricular (LV) function who develop right ventricular (RV) pacing-induced cardiomyopathy as a result of dual-chamber pacing can benefit from cardiac resynchronization therapy (CRT). We retrospectively assessed the effect of a CRT upgrade on RV pacing-induced cardiomyopathy.
Methods and Results: We reviewed the charts of patients who received a CRT device for RV pacing-induced cardiomyopathy. We assessed the effects of CRT on LV function, recovery, and other response parameters. From September 2005 through February 2009, 21 patients (13 men; aged 63 ± 9 years) underwent a treatment upgrade to a CRT system. Before the dual-chamber pacemaker was implanted, the LV ejection fraction (LVEF) was 53 ± 2.3%. After pacing, the LVEF was 31.2 ± 3.8%, the LV end-diastolic dimension (LVEDD) was 5.8 ± 0.5 cm, and B-type natriuretic peptide (BNP) levels were 426 ± 149 pg/mL. The duration of pacing before documentation of pacing-induced cardiomyopathy was 3.8 ± 1.5 months. All the patients had been on a stable medical regimen for at least 2 months. After the upgrade to CRT, the follow-up time was 4.9 ± 0.9 months. Sixteen patients (76%) reported a significant improvement in their symptoms. After the CRT upgrade, the LVEF increased to 37.4 ± 9.0% (P < 0.01 vs pre-CRT). The LVEDD decreased to 5.0 ± 1.0 cm (P = 0.03 vs pre-CRT), and BNP levels decreased to 139 ± 92 pg/mL (P = 0.08 vs pre-CRT).
Conclusion: A CRT upgrade is an effective treatment for RV pacing-induced cardiomyopathy and should be implemented as soon as the diagnosis is established. Unfortunately, about 24% of our patients did not respond to the upgrade. (PACE 2010; 37–40)     

Safety of Antitachycardia Pacing in Patients with Implantable Cardioverter Defibrillators and Severely Depressed Left Ventricular Function

The purpose of this study was to investigate the efficacy and safety of antitachycardia pacing (ATP) in third-generation implantable Cardioverter defibrillators (ICDs) for terminating spontaneously occurring ventricular tachycardias (VTs) in patients with severely depressed left ventricular (LV) function. Ninety-one patients with active ATP were followed for 16 ± 13 months. During this period, 775 VT episodes occurring in 36 patients were treated by ATP. The patients were divided into two groups according to their LV ejection fraction (LVEF): group A with LVEF ± 30% (n = 20), and group B with LVEF ± 30% (n = 16). There were no differences between both groups in age, gender, underlying heart disease, indication for ICD therapy, or drug therapy. The VT rates were comparable (group A: 183 ± 16 beats/min; group B: 180 ± 21 beats/min; P = NS). Eighty-three percent of all episodes (n = 332) in group A and 93% of the VTs (n = 443) in group B were ATP terminated (P ± 0.01). Ten percent of VTs in group A were accelerated by ATP into the ventricular fibrillation zone versus 2% in group B (P ± 0.01). The individual termination rate and acceleration rate per patient were comparable in both groups. All VT episodes unresponsive to ATP were converted by backup shocks. The efficacy of first-shock therapy was similar in both groups (group A: 89%; group B: 97%; P = NS). The proportion of patients who needed at least one backup shock for unsuccessful ATP was comparable in both groups (group A: 65%; group B: 56%; P= NS). We conclude that ATP is effective and safe in patients with recurrent VTs and severely depressed LV function, and it can be safely programmed in this group of patients to minimize the use of shock therapy.     

Ventricular Proarrhythmic Effects of Atrial Fibrillation are Modulated by Depolarization and Repolarization Anomalies in Patients with Left Ventricular Dysfunction

Background: Atrial fibrillation (AF) may have a ventricular proarrhythmic effect, particularly in the setting of heart failure. We assessed whether AF predicts appropriate implantable cardioverter-defibrillator (ICD) shocks in patients with left ventricular dysfunction and explored modulators of risk.
Methods and Results: A retrospective cohort study was conducted on 215 consecutive patients with ICDs for primary prevention having a left ventricular ejection fraction ≤ 35%. Mean age at ICD implantation was 61.0 ± 9.7 years and 17% were women. Overall, 22 patients (10.2%) experienced appropriate ICD shocks over a follow-up of 1.3 ± 0.7 years, corresponding to an actuarial event-rate of 5.8% per year. In univariate analysis, AF was associated with a 3.6-fold increased risk of appropriate shocks (P = 0.0037). Annual rates of appropriate ICD shocks in patients with and without AF were 12.9% and 3.5%, respectively (P = 0.0200). In multivariate stepwise Cox regression analyses controlling for baseline imbalances, demographic parameters, underlying heart disease, and therapy, history of AF independently predicted appropriate shocks (hazard ratio 2.7, P = 0.0278). Prolonged QRS duration (>130 ms) and QTc (>440 ms) modulated the effect of AF on appropriate shocks. Patients with both AF and QRS > 130 ms were more than five times more likely to receive an appropriate ICD shock (hazard ratio 5.4, P = 0.0396). Patients with AF and QTc > 440 ms experienced a greater than 12-fold increased risk of appropriate shocks (hazard ratio 12.7, P = 0.0177).
Conclusion: In prophylactic ICD recipients with left ventricular dysfunction, AF is associated with increased risk for ventricular tachyarrhythmias, particularly when combined with conduction and/or repolarization abnormalities.     

Device Use Patterns and Clinical Outcome of Implantable Cardioverter Defibrillator Patients with Moderate and Severe Impairment of Left Ventricular Function

The beneficial effects of implanted cardioverter defibrillator (ICD) therapy in patients with malignant ventricular tachyarrhythmias and variable degrees of left ventricular (LV) dysfunction are debated. ICD use and patient survival were examined in 128 patients with malignant ventricular arrhythmias and moderate or severe LV dys function. Group I included 64 patients with moderate LV dysfunction (LV ejection fraction of > 30%) and group H, 64 patients with severe LV dysfunction (LV ejection fracfion of ≤ 30%). Follow-up period ranged from 1 to 78 months. The two groups were similar in age, incidence of coronary artery disease and presenting arrhythmia. The mean LV ejection fraction in group I was 44%± 8% and group II was 22%± 5% (P < 0.0001). At 4 years of follow-up, 66% of patients from group I and 62% from group II (P = NS) had ICD activation for presumed ventricular tachyarrhythmia. Survival was calculated using actuarial analysis. Arrhythmic or sudden death mortality at 4 years of follow-up was 4% in group I and 7% in group II (P = NS). Cardiac mortality was for group I, 7% (P < 0.05), 12% (fP < 0,01), 15% (P < 0.01), and 15% (P < 0.01) for follow-up years 1, 2, 3, and 4, respectively. For group II, cardiac mortality was 27%, 36%, 41%, and 41% for follow-up years for 1, 2, 3, and 4, respectively. The majority of cardiac deaths in both groups was observed in the first 2 years of follow-up. However, in both groups, cardiac mortality was comparable in patients who did (users) and did not (nonusers) experience appropriate ICD shocks. Thus, the incidence of long-term ICD use is comparable in patients with moderate and severe LV dysfunction. Cardiac mortality is higher in patients with severe LV dysfunction in the first 4 years of follow-up irrespective of device use. The comparable long-term clinical outcome of ICD users and non users in patients with moderate or severe LV dysfunction can be related to elimination of arrhythmic mortality. Long-term patient survival in ICD recipients with severe LV dysfunction remains substantial even at 4 years of follow-up.     

Long-Term Performance of the Attain Model 4193 Left Ventricular Lead

Background: Cardiac resynchronization therapy (CRT) has proven to be a valuable therapy addition for patients with drug-refractory heart failure and a ventricular conduction delay. Delivery of CRT is dependent upon the successful implantation and chronic performance of a left ventricular (LV) pacing lead. This study assessed the long-term electrical performance and safety of a steroid-eluting, transvenous, over-the-wire, cardiac vein pacing lead.
Methods: The Attain Model 4193 LV lead (Medtronic, Inc, Minneapolis MN, USA) was successfully implanted in 1,070 patients with 286 patients completing 3 years of follow-up. Clinical data were collected at pre-implant, implant, and at 6-month intervals for 3 years.
Results: Over 3 years, the mean chronic pacing threshold ranged from 1.9 V to 2.1 V, the mean R-wave sensing amplitudes ranged between 13.6 mV and 15.0 mV, and the mean pacing impedance ranged between 562 ohms and 590 ohms. Additionally, the observed freedom from first post-implant LV-lead-related complications was 90.4%. Of 1,070 total patients, 82 experienced 89 LV-lead-related adverse events requiring invasive interventions or resulting in the termination of the CRT therapy. The LV lead was repositioned in 31 patients, replaced in 21 patients, and explanted/capped in four patients. There were no deaths related to the LV lead during implantation or during the follow-up period.
Conclusions: The data suggest that the 4193 LV lead is safe and effective over time. The LV lead electrical measurements remained stable through follow-up, demonstrating reliable long-term performance within the recommended value range at 36 months and had an acceptable complication rate.     

实时三维超声心动图定量评价心力衰竭患者左室收缩功能的研究

目的探讨实时三维超声心动图（RT-3DE）定量评价心力衰竭患者左室功能的可行性和准确性。方法36例心力衰竭患者（心衰组）和33例健康志愿者（正常组）均行M型超声（ME）、二维超声（2DE）和RT-3DE检查,并评价左室收缩功能。结果ME和2DE、RT-3D检测心衰组患者的LVEF值比较差异有统计学意义（P〈0.01）;心衰组LVEDV、LVESV值明显高于正常组,LVEF值明显低于正常组,差异有统计学意义（P〈0.01）。结论RT-3DE为临床上定量分析心力衰竭患者重构左室容积和收缩功能提供了一种无创、准确可信的新途径。     

Ventricular Arrhythmia Inducibility Predicts Subsequent ICD Activation in Nonischemic Cardiomyopathy Patients: A DEFINITE Substudy

Objectives: We evaluated whether electrophysiologic (EP) inducibility predicts the subsequent occurrence of spontaneous ventricular tachycardia (VT) or ventricular fibrillation (VF) in the Defibrillators in Nonischemic Cardiomyopathy Treatment Evaluation (DEFINITE) trial.
Background: Inducibility of ventricular arrhythmias has been widely used as a risk marker to select implantable cardioverter defibrillator (ICD) candidates, but is believed not to be predictive in nonischemic cardiomyopathy patients.
Methods: In DEFINITE, patients randomized to the ICD arm, but not the conventional arm, underwent noninvasive EP testing via the ICD shortly after ICD implantation using up to three extrastimuli at three cycle lengths plus burst pacing. Inducibility was defined as monomorphic or polymorphic VT or VF lasting 15 seconds. Patients were followed for a median of 29 ± 14 months (interquartile range = 2–41). An independent committee, blinded to inducibility status, characterized the rhythm triggering ICD shocks.
Results: Inducibility, found in 29 of 204 patients (VT in 13, VF in 16), was associated with diabetes (41.4% vs 20.6%, P = 0.014) and a slightly higher ejection fraction (23.2 ± 5.9 vs 20.5 ± 5.7, P = 0.021). In follow-up, 34.5% of the inducible group (10 of 29) experienced ICD therapy for VT or VF or arrhythmic death versus 12.0% (21 of 175) noninducible patients (hazard ratio = 2.60, P = 0.014).
Conclusions: In DEFINITE patients, inducibility of either VT or VF was associated with an increased likelihood of subsequent ICD therapy for VT or VF, and should be one factor considered in risk stratifying nonischemic cardiomyopathy patients.     

Long-term Stability of Endocardial Left Ventricular Pacing Leads Placed via the Coronary Sinus

Background: Left ventricular endocardial pacing leads placed via the coronary sinus (CS) are increasingly implanted to achieve cardiac resynchronization therapy (CRT); however, the long-term stability of these leads is unknown. We sought to determine the implant success and long-term stability of CS leads in our single center experience.
Methods: All consecutive patients who underwent CRT via implantation of the CS lead between January 1999 and December 2005 were included. Pacing thresholds at implant and during long-term follow-up were reviewed and the rate of acute (within 24 hours of implant) and chronic (>24 hours) lead failure was determined.
Results: A total of 512 patients (mean age 68 ± 12 years; 409 [80%] male) underwent CRT device implantation and were included. The CS lead implantation was successful on the initial implantation in 487 patients (95%) and subsequently successful in six patients (24%) in whom initial attempts were unsuccessful. Acute lead failure occurred in 25 patients (5.1%) and was most commonly due to persistent extra-cardiac stimulation. The rate of chronic lead failure was 4% in the first year and remained stable during long-term follow-up. The CS lead pacing thresholds remained stable with only minimal increase (1.42 ± 0.85 V/0.42 ± 0.25 ms vs 1.51 ± 1.05 V/0.47 ± 0.29 ms; P = 0.04).
Conclusions: Placement of a left ventricular pacing lead via the CS is feasible and safe in the vast majority of patients. Once placed, the CS leads remain stable with excellent pacing thresholds over the longer term.     

Feasibility Of Temporary Biventricular Pacing In Patients With Reduced Left Ventricular Function After Coronary Artery Bypass Grafting

Background and Methods: Biventricular pacing improves hemodynamics after weaning from cardiopulmonary bypass in patients with severely reduced left ventricular (LV) function undergoing coronary artery bypass grafting (CABG). We examined the feasibility of temporary biventricular pacing for 96 hours postoperatively. Unipolar epicardial wires were placed on the roof of the right atrium (RA), the right ventricular (RV) outflow tract, and the LV free lateral wall and connected to an external pacing device in 51 patients (mean LV ejection fraction 35 ± 4%). Pacing and sensing thresholds, lead survival and incidence of pacemaker dysfunction were determined.
Results: Atrial and RV pacing thresholds increased significantly by the 4th postoperative day, from 1.6 ± 0.2 to 2.5 ± 0.3 V at 0.5 ms (P = 0.03) at the RA, 1.4 ± 0.3 V to 2.7 ± 0.4 mV (P = 0.01) at the RV, and 1.9 ± 0.6 V to 2.9 ± 0.7 mV (P = 0.3) at the LV, while sensing thresholds decreased from 2.0 ± 0.2 to 1.7 ± 0.2 mV (P = 0.18) at the RA, 7.2 ± 0.8 to 5.1 ± 0.7 mV (P = 0.05) at the RV, and 9.4 ± 1.3 to 5.5 ± 1.1 mV (P = 0.02) at the LV. The cumulative overall incidence of lead failure was 24% by the 4th postoperative day, and was similar at the RV and LV. We observed no ventricular proarrhythmia due to pacing or temporary pacemaker malfunction.
Conclusions: Biventricular pacing after CABG using a standard external pacing system was feasible and safe.     

Evolution of Cardiac Autonomic Nervous Activity Indices in Patients Presenting with Transient Left Ventricular Apical Ballooning

Backround: Transient left ventricular (LV) apical ballooning (AB) is characterized by a rapidly reversible, acute LV systolic dysfunction, triggered by physical or emotional stress. Despite observations strongly suggesting catecholamine-mediated myocardial stunning due to enhanced sympathetic activity, the early time course of heart rate variability (HRV) has not been described.
Methods: We prospectively enrolled 39 consecutive patients (median age = 68 years, range 35–85 years, 38 women) with LV AB. Indices of HRV were extracted from 24-hour ambulatory electrocardiograms on the day of hospital admission, on days 2 and 3, and 3 months after the hospitalization.
Results: Within 48 hours after hospital admission, the indices of HRV were markedly depressed (standard deviation of normal-to-normal [NN] intervals [SDNN] 89.6 ± 19.9 ms; mean standard deviation of NN intervals for 5-minute segments [SDNNi] 37.8 ± 6.2 ms; root mean square of consecutive difference of normal-to-normal intervals [rMSSD] 23.0 ± 9 ms; standard deviation of the averages of NN intervals for all 5-minute segments [SDANN] 70.1 ± 18.0 ms; geometric triangular index [TI] 23.7 ± 5.9 ms), recovered in the subacute phase and had normalized at 3 months follow-up (SDNN 124.7 ± 24 ms; SDNNi 47.1 ± 5.7 ms; rMSSD 31.1 ± 10.5 ms; SDANN 118.5 ± 27 ms; TI 31.2 ± 8 ms; all P < 0.05). Mean RR-interval increased from 845 ± 121 ms on day 1, to 929 ± 84 ms at 3 months (P = 0.06).
Conclusions: A marked depression of cardiac parasympathetic activity was observed in the acute phase of LV AB, followed by recovery of autonomic modulation between the subacute and the chronic phases. The rapid return of parasympathetic function may partially explain the favorable outcomes of patients presenting with LV AB.     

Segmental Wall Motion Abnormality Analyzed by Equilibrium Radionuclide Angiography and Improvement in Ventricular Function by Cardiac Resynchronization Therapy

Introduction: The purpose of this study was to determine the impact of the left ventricular (LV) segmental wall motion abnormalities detected by equilibrium radionuclide angiography (ERNA) on the improvement in LV and right ventricular (RV) function during biventricular (BIV) stimulation .
Results: We studied 28 patients in NYHA functional classes III or IV and QRS duration >150 ms on resting electrocardiogram. ERNA was performed before and during BIV stimulation at a 6-month follow-up. A significant shortening of QRS duration was observed during BIV stimulation (165 ± 5 ms before vs 133 ± 6 ms during, P < 0.01). Wall motion abnormalities (WMA) were observed in 16 patients (10 with nonischemic cardiomyopathies). In this group, LV and RV ejection fractions (EF) did not increase during BIV stimulation (LVEF = 22 ± 2% vs 20 ± 1.6%, ns; RVEF = 34 ± 3% vs 37 ± 3.8%, ns). Significant increases in RVEF (23 ± 3.2 %→ 38 ± 2.9%, P = 0.001) and LVEF (20 ± 2.5 %→ 30 ± 3%, P = 0.01) were observed in the group of patients without segmental WMA and with global hypokinesia (GH). In this group, a significant decrease in the dispersion in the phase of RV contraction was observed (SD = 39 ± 5 vs 26 ± 2 ms; P < 0.01). WMA predicted an increase in LVEF, in contrast to a baseline 6-minute-walk test, maximal oxygen consumption and LVEF, or amount of QRS shortening.
Conclusions: BIV stimulation increased in LV and RV EF in patients with ventricular dyssynchrony in absence of segmental WMA. ERNA was reliable in the selection of candidates for CRT.     

门控心血池断层显像测定冠心病患者左室容积和功能的研究

对１０例正常人和２６例冠心病患者进行了门控心血池断层显像，测定其左室舒张末期容积（ＩＶＥＤＶ）、左室收缩末期容积（ＬＶＥＳＶ）、每搏射血量（ＳＶ）及左室射血分数（ＬＶＥＦ）。结果显示：冠心病组的ＬＶＥＤＶ、ＬＶＥＳＶ＞正常对照组，ＬＶＥＦ＜正常对照组，ＳＶ在二组之间无显著性差异。重复性试验表明左室容积测定结果稳定。认为门控心血池断层显像是一种直接、准确的无创伤性测定左室功能的显像方法，对冠心病左室功能评价有临床应用价值。     

256层螺旋 CT 与超声心动图评价左心室功能的相关性分析

【目的】探讨256层螺旋 CT(MSCT)与超声心动图评价左心室功能的相关性。【方法】前瞻性收集2012年8月至2013年12月就诊本院并于10日内均行 MSCT 冠状动脉血管造影(CTA)及经胸超声心动图检查者89例。所有患者按心功能(New York Heart Association ,NYHA)分成四个组。比较两种方法检测的左室舒张末期容积(EDV)、左室收缩末期容积(ESV)、左室每搏输出量(SV)和左室射血分数(EF)值,MSCT 评价心功能与临床分级的相关性。【结果】各心功能组 MSCT 与超声心动图所测得的左室功能参数 EDV、ESV、SV 和 EF 值比较差异无统计学意义(P >0.05);经相关性检验两种方法的测量值高度相关(P <0.05);NYHA 不同分级的 EDV、ESV 及 EF 值比较,差异有统计学意义(P <0.05),而 SV 值比较差异无统计学意义。【结论】MSCT 冠状动脉CTA 评价心功能较为准确、可靠;与超声心动图测量结果比较具有很好的相关性。     

Relationship Between Global Myocardial Index and Automatic Left Ventricular Border Detection Pattern to Identify Biventricular Pacing Candidates

Objective of the Study: to evaluate the relation between global myocardial index (GMI) and the pattern of left ventricular (LV) volume curves variation, using automatic border detection (ABD), and their role in assessing LV asynchrony.
Methods: We studied 52 patients (mean age = 55 ± 17 years) with dilated cardiomyopathy. QRS duration (QRSd) and GMI were measured. Currently accepted TDI and M-mode parameters were used to indicate LV dyssynchrony. On-line continuous LV volume changes were recorded using ABD. Ejection time (ET ABD) was measured from the ABD wave-forms as time interval between maximal and minimal volume variation during LV electromechanical systole. We derived the ejection time index (ETiABD) as the ratio between ET ABD and RR interval (ETiABD = ET/RR).
Results: 31 patients had a QRSd >120 ms and 21 patients had a QRSd <120 ms. Ventricular dyssynchrony was observed in 39 patients (29 patients had a QRSd > 120 ms). GMI was significantly higher in patients with, than in patients without ventricular dyssynchrony (1.06 ± 0.18 vs 0.73 ± 0.13, P = 0.0001), while ETABD was significantly smaller (233 ± 39 ms vs 321 ± 28 ms, P = 0.0001). The corresponding difference for ETiABD was 26.9 ± 6.8% vs 6.3 ± 4%, P < 0.0001. By simple regression analysis an inverse linear correlation was observed between GMI and ETiABD (r²=–0.51, P < 0.0001). The pattern of ABD waveforms showed increased isovolumic contraction and relaxation times in patients with LV asynchrony, similar to the GMI pattern.
Conclusions: Regional delays in ventricular activation cause uncoordinated and prolonged ventricular contractions, with lengthening of the isovolumic contraction and relaxation times and shortening of the time available for filling and ejection. GMI explores these parameters and together with ABD might be useful to identify patients with ventricular asynchrony.     

No Correlation Between Atrial Natriuretic Peptide Concentrations and Echocardiographic Measurements of Left Atrial Size or Left Ventricular Size and Function in Patients with Persistent Atrial Fibrillation

Atrial fibrillation (AF) may be associated with activation of atrial natriuretic peptide (ANP). The exact trigger for the release of ANP is still being debated. Atrial volume, pressure, and wall stretch are considered to be the main determinants of ANP activation. The aim of the study was to evaluate plasma ANP concentrations in patients with persistent AF and to analyze the echocardiographic determinants of ANP concentration in this group. The study population included 67 patients, 59 ± 7 years of age, with a median AF duration of 5.5 months (range 0.1–12). The relationship between plasma ANP concentrations and echocardiographic left atrial (LA) diameter and volume, and left ventricular (LV) diameter and ejection fraction (EF) was analyzed by logistic regression analysis. The median baseline plasma ANP concentration was 63 pg/mL (range 21–126) in the study group versus 34 pg/mL (range 16–73) in a control group. The mean left antero-posterior atrial dimension, LA volume, LV enddiastolic diameter, and LVEF were 48 mm, 104 mL, 52 mm, and 54%, respectively. A significant linear positive correlation was found between plasma ANP concentration and maximal LA volume (r = 0.62, P < 0.01). A negative correlation was found between LVEF and plasma ANP concentration (r =−0.42, P = 0.01). However, by multivariate regression analysis, no echocardiographic parameter was an independent predictor of plasma ANP concentration. Plasma ANP concentrations were independent of echocardiographic measurements of LA size or LV size and function in patients with persistent AF.     

A New Endocardial "Over-the-Wire" or Stylet-Driven Left Ventricular Lead:

Transvenous left ventricular (LV) leads are primarily inserted "over-the-wire" (OTW). However, a stylet-driven (SD) approach may be a helpful alternative. A new polyurethane-coated, unipolar LV lead can be placed either by a stylet or a guide wire, which can be inserted into the lead body from both ends. The multicenter OVID study evaluates the clinical performance of this new steroid- and nonsteroid eluting lead. The primary endpoint is the LV lead implant success rate after identification of the coronary sinus (CS). Secondary endpoints include complication rate, short- and long-term lead characteristics, overall procedure and LV lead placement duration, total fluoroscopy time, and lead handling characteristics ratings. To date, 96 patients with heart failure (68 ± 9 years old, 76% men) are enrolled. The CS was identified in 95 patients and, in 85 (88.5%), the LV lead was successfully implanted. The final lead positioning was lateral in 41%, posterolateral in 35%, anterolateral in 18%, and great cardiac vein in 6% of patients. In 70%, the 85 successful implantations, both stylet-driven and guide-wire techniques were used, a stylet only was used in 22%, and a guide wire only in 8%. Mean overall duration of 85 successful procedures was 112 ± 40 minutes, total fluoroscopy time 28 ± 15 minutes, and the duration of LV lead placement was 35 ± 29 minutes. During a 3-month follow-up, the loss of LV capture occurred in three and phrenic nerve stimulation in six patients. The mean long-term pacing threshold is 0.8 V/0.5 ms and pacing impedance is 550 Ω. The OVID data suggest that these new leads are safe and effective. The choice of both OTW and SD techniques during lead implantation offers greater procedural flexibility.