速度向量成像技术在心力衰竭患者同步化治疗中的应用

目的研究速度向量成像技术(VVI)在指导心脏再同步化治疗(CRT)患者的筛选、左室电极的植入及评价CRT疗效的临床应用价值。方法药物难治性心力衰竭患者17例,年龄60±13岁,NYHA心功能分级Ⅲ或Ⅳ级,术前均经VVI评价左室内十二节段任2个节段收缩达峰时间的最大差值及标准差,并分析左室内收缩最延迟部位。行CRT治疗,将左室电极植入左心收缩最延迟部位相关的冠状静脉窦分支血管内。分别在术后第1,3个月进行随访。观察CRT治疗后患者心功能分级、超声心动图测定心功能指标,以及VVI评价同步性参数的变化。结果随访3个月,患者心功能分级提高I～II级,6min步行距离由309.77±76.05m增至402.06±87.09m(P<0.05),左室射血分数由0.32±0.04增加至0.42±0.07(P<0.01),二尖瓣返流减少。VVI结果显示室内不同步较术前有明显改善。结论VVI技术可用于评价心脏的同步化状态、指导CRT的治疗及评价疗效。     

Erfahrungen mit einer neuen transvenösen Sonde zur linksventrikulären Stimulation

BACKGROUND: Left ventricular and biventricular pacing has recently been introduced as a new therapy for chronic heart failure in selected patients. We report our initial experience with a new electrode for transvenous left epicardial pacing via tributaries of the coronary sinus. PATIENTS AND METHOD: Inclusion criteria were: chronic heart failure NYHA > or = II, QRS-duration > 120 ms, left ventricular ejection fraction < 35%. Dual chamber pacemakers (CPI Contak TR) or defibrillators (CPI Contak CD) designed for atrial triggered biventricular stimulation were implanted in conjunction with the CPI Easytrak-lead for left ventricular pacing in a coronary vein. Lead placement was achieved via a subclavian vein access and a preformed guiding catheter for coronary sinus insertion. RESULTS: In 13 of 16 patients (81%) the left ventricular lead was implanted successfully in a mid to distal posterior or anterolateral vein. Lead insertion could not be achieved in 2 patients with significant cardiomegaly and right atrial enlargement (12.5%), while 1 patient with a history of myocardial infarction and small anterior ventricular aneurysm had inacceptable high left ventricular pacing thresholds intraoperatively. The implantation was well tolerated by all patients without complications. There was no case of lead dysfunction (mean follow-up time: 142 +/- 126 days). Intraoperative electrode measurements and chronic parameters (> or = 3 months, n = 8) are given in Table 1. CONCLUSION: In the past left ventricular pacing has mainly been achieved by epicardially placed electrodes after thoracotomy with conventional electrodes. This new approach for chronic left ventricular pacing uses the familiar transvenous over-the-wire technique in combination with a newly developed guiding catheter and electrode for pacing in left epicardial veins. Lead placement was shown to be safe and success rate was higher than in previous reports with standard electrodes. We conclude that left epicardial lead placement with the over-the-wire technique and a preformed guiding catheter for coronary sinus access presents as a safe and maybe more efficient method for left ventricular pacing.     

右房左室起搏治疗慢性心力衰竭伴室内传导阻滞患者的初步临床观察

观察右房 左室起搏治疗慢性心力衰竭 (简称心衰 )的临床效果。选择 1 6例充血性心衰患者 (NYHA分级Ⅲ Ⅳ级 ) ,男 1 0例、女 6例 ,年龄 6 8.4± 6岁 ;均为窦性心律 ,合并有Ⅰ度房室阻滞 ,完全性左束支阻滞。按安置起搏器的模式分为右房 左室起搏治疗组 (LV组 ,n =6 ) ,右房双室起搏治疗组 (BiV组 ,n =1 0 )。左室起搏电极分别放置于心大静脉左室侧后分支 9例 ,心大静脉左室后分支 7例。观察起搏治疗前后左室心功能参数、6min步行距离、左室壁运动的同步性及体表心电图的变化。结果 :BiV组左室射血分数 (LVEF)由术前的 0 .2 3提高至 0 .31 (P <0 .0 0 1 ) ;在LV组LVEF由术前的 0 .2 4提高至 0 .33(P <0 .0 0 1 ) ;左室舒张末期容积指数在二组分别由术前的 1 4 9± 5 1ml/m2 和 1 5 3±5 3ml/m2 下降至 1 1 6± 38ml/m2 和 1 2 1± 4 1ml/m2 (P均 <0 .0 0 1 ) ;室间隔与左室后壁运动的延迟时间在二组分别由术前的 1 95± 94ms和 1 97± 89ms下降至 1 7± 6 0ms及 1 6± 5 6ms(P均 <0 .0 0 1 )。 6min步行距离则分别由术前的4 0 3± 5 3m和 4 0 1± 5 9m提高至 4 4 1± 6 2m和 4 4 2± 6 7m(P均 <0 .0 5 )。结论 :初步临床观察提示右房 左室起搏治疗与右房双室起搏治疗相比 ,同样可有效地改善慢性心衰?     

心脏再同步化治疗左室电极导线的理想起搏部位及其个体化定位植入方法

左室电极导线的起搏部位是影响心脏再同步化治疗疗效的重要因素。多项临床研究表明左室电极导线的理想起搏部位是左室最延迟的机械收缩部位并且要避开心尖及疤痕区域。心脏再同步化治疗术前个体化确定最延迟机械收缩部位的方法有多种,但是存在心脏再同步化治疗术前确定的理想部位与心脏再同步化治疗术中经冠状静脉窦及分支造影确定的可植入左室电极导线血管分支不匹配的问题,因而对这部分患者失去了左室电极导线植入的指导意义。电生理标测冠状静脉窦分支最延迟电激动处靶向植入左室导线的心脏再同步化治疗可能是临床一种简便、实用、有效的方法。     

Terapêutica de ressincronização cardíaca e efeito pró‐arrítmico: um problema que deve ser lembrado

The demonstrated benefits of cardiac resynchronization therapy (CRT) in reducing mortality and hospitalizations for heart failure, improving NYHA functional class and inducing reverse remodeling have led to its increasing use in clinical practice. However, its potential contribution to complex ventricular arrhythmias is controversial.We present the case of a female patient with valvular heart failure and severe systolic dysfunction, in NYHA class III and under optimal medical therapy, without previous documented ventricular arrhythmias. After implantation of a CRT defibrillator, she suffered an arrhythmic storm with multiple episodes of monomorphic ventricular tachycardia (VT), requiring 12 shocks. Subsequently, a pattern of ventricular bigeminy was observed, as well as reproducible VT runs induced by biventricular pacing.Since no other vein of the coronary sinus system was accessible, it was decided to implant an epicardial lead to stimulate the left ventricle, positioned in the left ventricular mid‐lateral wall. No arrhythmias were detected in the following six months.This case highlights the possible proarrhythmic effect of biventricular pacing with a left ventricular lead positioned in the coronary sinus venous system.     

The use of a "side-wire" permanent transvenous pacing electrode for left ventricular pacing.

It has been reported that biventricular pacing can improve the symptomatic status of patients with heart failure. However, using currently available transvenous left ventricular pacemaker leads the implantation procedure is difficult and has a high failure rate. We report the successful use of a new type of left ventricular pacing lead, the 'side-wire' pacing lead. This lead is initially introduced through a specifically designed guiding sheath to aid coronary sinus cannulation and then over a pre-positioned guide wire to aid final positioning. The more widespread introduction of this type of left ventricular pacing lead may reduce the difficulty of left ventricular pacing via the coronary sinus and thus improve the overall success rate of this therapeutic approach.     

Persistent left‐sided superior vena cava – a pacing challenge

A left sided superior vena cava (LSVC) occurs in 0.3% of the population. LSVC normally drains into the right atrium through a dilated coronary sinus. We illustrate two cases of dual chamber permanent pacemaker implantation by using (1) left subclavian vein in a 35‐year‐old woman with symptomatic Mobitz type II atrioventricular block; and (2) right subclavian vein in a 64‐year‐old man who was hospitalized with bradycardia, complete heart block, and alternating bundle branch block.

After accessing the subclavian vein, the pacing leads were advanced into the LSVC, which was situated to the left of the vertebral column in the mediastinum. The leads followed the course of the LSVC medially before entering into the right atrium. Once inside the right atrium, the ventricular lead made a U‐turn towards the tricuspid valve and into the right ventricle by shaping the stylet, and it was helped by right atrial contraction. An active fixation atrial lead was used in both cases to secure a satisfactory location within the right atrium. A small volume of contrast can be injected into the pacing sheath to visualize the coronary sinus opening into the right atrium, and the right ventricle. Fluoroscopy in oblique views can be helpful in guiding the atrial lead into the anteriorly positioned atrial appendage.

In emergency transvenous ventricular temporary pacing where the subclavian or internal jugular vein is used, it is important to recognize the presence of a LSVC. The lead should first be directed into the right atrium and then looped back into the right ventricle. Excessive force must be avoided to prevent cardiac perforation and tamponade. If this is not successful, access through a femoral vein should be attempted.     

Clinical investigation of left ventricular pacing using coronary sinus in patients with mechanical prosthetic tricuspid valve replacement

Background

Although transvenous right ventricular (RV) endocardial lead placement is routine practice in clinical pacing, RV inaccessibility in certain clinical situations mandates the search for other sites.

Hypothesis

This study is aimed to verify whether left ventricular lead through coronary sinus is safe and efficient.

Methods

Based on a retrospective analysis of a single‐center series of 4 patients with inaccessibility for RV pacing, we report on the feasibility and reliability of coronary sinus (CS) pacing via left ventricular (LV) lead, which usually is used in cardiac resynchronization therapy. Four patients with valvular heart disease and bradycardias post–mechanical prosthetic tricuspid valve replacement were studied. The LV leads were implanted into the lateral vein or great cardiac vein of the CS, and all parameters were programmed postprocedure.

Results

In all cases procedures yielded favorable parameters, with 1 CS dissection. At long‐term follow‐up, there was no threshold increase or lead dislocation.

Conclusions

LV lead implantation through the CS appears safe and efficacious in patients with inaccessibility for RV pacing.

     

心脏再同步化治疗术中所遇问题及并发症的处理

目的介绍心脏再同步化治疗(CRT)手术中所遇的问题及并发症处理。方法回顾分析单中心CRT植入过程中所遇问题及并发症的发生与相应处理。结果共有4例患者出现问题或并发症,其中男3例、女1例。例1冠状静脉窦难以寻找,而改为右室双部位起搏;例2术中发生冠状静脉窦静脉夹层;例3术中突发急性左心衰竭,左室电极导线难以固定而留置经皮冠状动脉腔内成形术(PTCA)钢丝;例4左室电极导线置于心中静脉,在右房、右室电极植入时反复出现空气栓塞。结论 CRT术前应充分抗心力衰竭治疗,术中避免静脉夹层及空气栓塞,必要时右室双部位起搏,难以固定时留置PTCA钢丝于靶静脉内是可行的。     

2187导线在左心室起搏中的应用价值

目的寻找左心室电极导线的导入途经和技术要点及其在双心室起搏中的临床实用价值.方法 9例病人,男性8例,均为药物治疗无效合并CLBBB的顽固性心力衰竭.CS造影7例采用逆行法,2例采用顺行法显示CS.选择可剥脱CS导引导管和左室电极导线(Medtronic,2187),采用左锁骨下静脉穿刺法,经CS将电极导线置于CS左心室属支,起搏左心室.结果无论是逆行还是顺行冠状动脉造影,均清晰显示CS及其属支静脉.6例病人经导引导管将2187导线成功导入靶静脉,3例病人直接导入2187导线.电极导线尖端1例插进心大静脉远端,2例位于左室侧缘静脉,2例放在左室后静脉, 4例导入左室后侧静脉.导线到位后测量的各起搏参数均符合起搏要求,长期随访未见导线脱位和起搏功能的变化.结论 CS顺行和逆行造影均可清晰显示CS及其属支;直接或经导引导管皆可将2187电极导线导入靶静脉;应用2187型LV电极导线经CS左心室心外膜起搏技术可行、安全可靠,可广泛临床应用.     

Erfahrungen mit einer neuen transven?sen Sonde zur linksventrikul?ren Stimulation

Hintergrund: Die links- und biventrikuläre Stimulation stellt ein neues Verfahren zur Behandlung der chronischen Herzinsuffizienz dar. Wir berichten über unsere Erfahrungen mit der Implantation einer neuen Schrittmacherelektrode mit Hilfe der Over-the-Wire-Technik zur linksventrikulären Stimulation in einer epikardialen Herzvene. Patienten und Methode: Bei 16 Patienten mit therapierefraktärer Herzinsuffizienz (NYHA S II), eingeschränkter linksventrikulärer Funktion (Ejektionsfraktion < 35%) und QRS-Dauer > 120 ms wurde die Indikation für ein linksventrikuläres oder biventrikuläres Defibrillator- oder Schrittmachersystem gestellt (linksventrikulär: drei, biventrikulär: 13). Ergebnisse: Bei 13 Patienten (81%) gelang die Platzierung der linksventrikulären Elektrode in einer anterolateralen oder posterioren Vene. Bei zwei Patienten (12,5%) konnte der Koronarsinus nicht sondiert werden. Es fanden sich insgesamt gute intraoperative Elektrodenmesswerte (linksventrikuläre Reizschwelle 1,0 - 0,7 V [0,5 ms], Impedanz 639 - 267 Ohm, R-Amplitude 11,0 - 4,7 mV [MW - SA]). Bei einem Patienten mit umschriebenem Vorderwandaneurysma konnte intraoperativ keine akzeptable linksventrikuläre Reizschwelle erzielt werden. Die Operation wurde von allen Patienten gut toleriert. In einem Beobachtungszeitraum von 142 - 126 Tagen kam es zu keiner Sondendysfunktion. Von acht Patienten liegen chronische Elektrodenmesswerte vor (Beobachtungszeitraum S 3 Monate): Impedanz 524 - 191 Ohm, R-Amplitude 12,0 - 6,0 mV, linksventrikuläre Reizschwelle 1,4 - 1,2 V. Schlussfolgerung: Die Implantation einer Schrittmacherelektrode in das koronare Venensystem mittels der Over-the-Wire-Technik erscheint als sichere Methode zur vollständig transvenösen Stimulation des linken Ventrikels und könnte eine effiziente und komplikationsarme Alternative zu konventionellen Techniken darstellen. Background: Left ventricular and biventricular pacing has recently been introduced as a new therapy for chronic heart failure in selected patients. We report our initial experience with a new electrode for transvenous left epicardial pacing via tributaries of the coronary sinus. Patients and Method: Inclusion criteria were: chronic heart failure NYHA S II, QRS-duration > 120 ms, left ventricular ejection fraction < 35%. Dual chamber pacemakers (CPI Contak TR^®) or defibrillators (CPI Contak CD^®) designed for atrial triggered biventricular stimulation were implanted in conjunction with the CPI Easytrak^®-lead for left ventricular pacing in a coronary vein. Lead placement was achieved via a subclavian vein access and a preformed guiding catheter for coronary sinus insertion. Results: In 13 of 16 patients (81%) the left ventricular lead was implanted successfully in a mid to distal posterior or anterolateral vein. Lead insertion could not be achieved in 2 patients with significant cardiomegaly and right atrial enlargement (12.5%), while 1 patient with a history of myocardial infarction and small anterior ventricular aneurysm had inacceptable high left ventricular pacing thresholds intraoperatively. The implantation was well tolerated by all patients without complications. There was no case of lead dysfunction (mean follow-up time: 142 끆 days). Intraoperative electrode measurements and chronic parameters (S 3 months, n = 8) are given in Table 1. Conclusion: In the past left ventricular pacing has mainly been achieved by epicardially placed electrodes after thoracotomy with conventional electrodes. This new approach for chronic left ventricular pacing uses the familiar transvenous over-the-wire technique in combination with a newly developed guiding catheter and electrode for pacing in left epicardial veins. Lead placement was shown to be safe and success rate was higher than in previous reports with standard electrodes. We conclude that left epicardial lead placement with the over-the-wire technique and a preformed guiding catheter for coronary sinus access presents as a safe and maybe more efficient method for left ventricular pacing.     

Caudocranial transseptal approach for placement of endocardial left ventricular leads

Cardiac resynchronization therapy (CRT) is associated with improvement in the quality of life, hospitalization rates, and mortality in patients with left ventricular dysfunction and evidence of the right ventricle‐left ventricle (RV‐LV) desynchrony. Implant failure rates and patient outcomes have improved with the advent of quadripolar leads, yet alternatives to traditional coronary sinus (CS) LV lead placement is sought for in a subset of advanced heart failure patients with difficult CS anatomy, phrenic nerve stimulation or in nonresponders. Endocardial left ventricular pacing (EnLVP) in chronically anticoagulated patients has been reported as an alternative using different approaches, techniques, and tools with acceptable short and long term adverse events. We present a case of successful EnLVP achieved for CRT using standard techniques and commonly available tools in a patient on chronic direct oral anticoagulation with recurrent heart failure admissions who failed traditional epicardial LV pacing.     

Left ventricular pacing through coronary sinus tributaries: initial experience.

BACKGROUND: Left ventricular pacing is increasingly being used as a part of biventricular pacing in congestive heart failure but data on safety, feasibility, reliability and lead maturation are sparse. METHODS AND RESULTS: Seventeen patients (13 males and 4 females) with persistent symptomatic degenerative complete heart block underwent temporary left ventricular pacing by a left subclavian puncture through the coronary sinus to its tributaries using a unipolar permanent pacing lead connected to an external pulse generator. The left ventricular pacing was done for two weeks. Permanent right ventricular apical pacing was also done at the same time through a right cephalic vein cut-down or subclavian puncture and the pacing rate was kept below that of the initial left ventricular pacing rate. Pacing parameters of the left and right ventricles were assessed at the time of implantation and at two weeks. Out of 17 patients, left ventricular pacing was successful in 11 (67.7%) patients. The time taken for the total procedure was 56+/-18.1 min. Lead displacement was noted in one patient without loss of pacing. At the time of implant and after two weeks, left ventricular pacing threshold, impedance, R wave height and slew rate were not different as compared to right ventricular pacing. Holter recording for 24 hours revealed regular left ventricular pacing at the end of two weeks in all patients. CONCLUSIONS: The present study shows that left ventricular pacing through coronary sinus tributaries is feasible and reliable. Acute and subacute maturation of left ventricular pacing are similar to right ventricular apical pacing.     

Novel Steerable Telescoping Catheter System for Implantation of Left Ventricular Pacing Leads

Advances in left ventricular transvenous lead delivery systems for biventricular pacing are leading to more refined techniques, shorter procedure times and higher implant success rates. Despite these advances, the inability to successfully cannulate the coronary sinus and deliver a lead to a distal location are still major causes of prolonged procedures times and implant failures. The pathophysiologic process of heart failure results in dilatation of the right atrium as well as other morphological changes in cardiac anatomy. Additionally, cannulation can be further complicated by congenital anomalous cardiac anatomy. This report describes the implant of a biventricular pacing system using a novel, steerable 7 French catheter system developed to aid in the cannulation of the coronary sinus ostium and its venous branches. The steerable catheter is used in conjunction with a 9 French braided sheath and guide-wire to create a telescoping system. The use of new tools and methods as described provides insight into available options for left ventricular transvenous lead implantation and dealing with difficult anatomy.Additional Notes This case, in part, was presented at Cardiostim 2004 (June 16–19, 2004, Nice Acropolis, Nice).     

A new paradigm for physiologic ventricular pacing.

Clinical trials in patients with pacemakers for sinus node dysfunction or atrioventricular block (AVB) and implantable cardioverter-defibrillators provide increasing evidence showing that desynchronization of ventricular electrical activation and contraction, induced by conventional right ventricular apex (RVA) pacing, is a serious threat for long-term cardiac morbidity and mortality. The risk of heart failure is increased even in hearts with initially normal pump function and in case of part-time ventricular pacing. These epidemiologic data fit with knowledge from decades of pathophysiological research, indicating that right ventricular (RV) pacing creates abnormal contraction, reduced pump function, hypertrophy, and ultrastructural abnormalities. This paper presents a new paradigm that aims to tailor ventricular pacing to the individual patient to achieve a way of pacing that is as physiologic as possible. In patients without AVB and no intraventricular conduction abnormalities, ventricular pacing should be avoided as much as possible, using atrial-based pacing. In patients with AVB, alternate single-site RV or left ventricular pacing or biventricular pacing may be superior to RVA pacing. Efforts to optimize the pacing mode or site should be greater in patients with a longer expected duration of pacing, poorer cardiac function, and larger mechanical asynchrony. Awareness of the problem of desynchronization should also lead to more regular monitoring of cardiac pump function and mechanical asynchrony in any patient with ventricular pacing.     

A new paradigm for physiologic ventricular pacing

Clinical trials in patients with pacemakers for sinus node dysfunction or atrioventricular block (AVB) and implantable cardioverter-defibrillators provide increasing evidence showing that desynchronization of ventricular electrical activation and contraction, induced by conventional right ventricular apex (RVA) pacing, is a serious threat for long-term cardiac morbidity and mortality. The risk of heart failure is increased even in hearts with initially normal pump function and in case of part-time ventricular pacing. These epidemiologic data fit with knowledge from decades of pathophysiological research, indicating that right ventricular (RV) pacing creates abnormal contraction, reduced pump function, hypertrophy, and ultrastructural abnormalities. This paper presents a new paradigm that aims to tailor ventricular pacing to the individual patient to achieve a way of pacing that is as physiologic as possible. In patients without AVB and no intraventricular conduction abnormalities, ventricular pacing should be avoided as much as possible, using atrial-based pacing. In patients with AVB, alternate single-site RV or left ventricular pacing or biventricular pacing may be superior to RVA pacing. Efforts to optimize the pacing mode or site should be greater in patients with a longer expected duration of pacing, poorer cardiac function, and larger mechanical asynchrony. Awareness of the problem of desynchronization should also lead to more regular monitoring of cardiac pump function and mechanical asynchrony in any patient with ventricular pacing.     

Cardiac resynchronisation therapy

Left ventricular dysfunction is often associated with myocardial conduction slowing which is usually seen clinically as left bundle branch block on the surface ECG. Left bundle branch block causes asynchronous contraction of the left ventricle with the ventricular septum contracting early and the lateral left ventricular wall contracting late. This leads to a reduction in cardiac output and myocardial contraction efficiency and systolic mitral regurgitation worsens. Patients with this combination of findings may benefit from the implantation of a pacing system that aims to normalise conduction and "resynchronise" the ventricles. This mode of cardiac stimulation is referred to as "biventricular" pacing and relies on the implantation of an additional pacing lead on the epicardial surface of the left ventricle. This is achieved by selectively cannulating the coronary sinus and passing a pacing lead via a posterolateral coronary sinus tributary to an appropriate location. This lead, as well as the two conventional right atrial and right ventricular leads, is then attached to a specialised pacemaker. The procedure may be challenging and usually takes 1-2h depending on the operator's experience. The QRS complex shortens as the lateral wall of the left ventricle becomes "pre-excited" and contracts in concert with the ventricular septum. Improved haemodynamics result immediately and favourable reverse left ventricular remodelling occurs over subsequent weeks. Recently, these physiologic advantages have been translated into real clinical gains for patients with biventricular pacemakers where improvements in exercise tolerance and quality of life and reduced hospitalisations for recurrent heart failure have been conclusively demonstrated.     

心室再同步化起搏的心电图表现及随访

目的探讨不同心室起搏部位体表十二导联心电图的变化及在双心室再同步起搏(CRT)随访中的应用。方法22例资料完整的充血性心力衰竭患者进行双心室再同步起搏治疗,其中21例经静脉置入左室导线,1例因冠状静脉窦畸形经胸左室外膜导线置入;右室导线均放置在心尖部。22例分别记录无起搏、右室起搏、左室起搏及双心室同步起搏四种不同状态下的十二导联心电图。结果22例术前心电图显示完全性左束支传导阻滞(CLBBB)16例,完全性心室内传导阻滞6例,行右室心尖部起搏时胸前导联(V1)均呈CLBBB型,肢体导联额面电轴左偏,Ⅰ导联呈r、R型占100%,左室起搏时胸前导联(V1)均呈右束支传导阻滞(CRBBB)型,额面电轴右偏,Ⅰ导联呈q、Q、QS型20例,占91%;双心室同步起搏后胸前导联(V1)呈CLBBB型13例,呈CRBBB型9例,额面电轴均右偏,Ⅰ导联呈q、Q、QS型占86.5%。结论不同部位心室起搏具有不同的心电图表现,双心室同步起搏具有特征性的心电图形态,CRT随访时通过对心电图形态和时限的观察有助于判断是否实现真正有效的双心室再同步起搏。     

Assessment of regional wall motion using strain Doppler imaging during right ventricular bifocal pacing in a patient with severe congestive heart failure: a case report

A 79-year-old man presented with dilated cardiomyopathy and chronic atrial fibrillation. A DDD pacemaker was implanted due to sick sinus syndrome. His left ventricular ejection fraction was 23%. He was repeatedly admitted with congestive heart failure. Although cardiac resynchronization therapy was attempted, insertion of a pacing lead into the coronary sinus failed. Right ventricular bifocal pacing was done. The QRS width was shortened to 155 msec during bifocal pacing and 157 msec during right ventricular outflow pacing from 221 msec during right ventricular apical pacing. Heart failure was improved from New York Heart Association class III to II. Regional wall motion was assessed by strain of the myocardium. Bifocal pacing increased stroke volume due to improvement of longitudinal dyssynchrony of the septal and lateral walls. Bifocal pacing is effective for patients with severe congestive heart failure in whom biventricular pacing therapy has failed. Strain Doppler imaging is useful for the assessment of regional wall motion during cardiac pacing.     

The effects of ventricular asynchrony on myocardial perfusion

Asynchronous depolarization and contraction sequence, secondary to intraventricular conduction defects or to permanent right ventricular apical pacing, is associated with adverse effects that may be clinically evident in the failing heart. Experimental and clinical studies have suggested that asynchronous ventricular contraction deteriorates left ventricular performance and induces unfavourable left ventricular remodelling. Although such contraction does not appear to affect resting coronary artery blood flow, it increases endomyocardial pressure during diastole and decreases regional myocardial perfusion in the interventricular septum. The magnitude of these effects may correlate with the duration of the asynchrony. Despite these detrimental effects, there is no evidence that ventricular asynchrony reduces collateral myocardial blood flow, myocardial oxygen consumption or cardiac efficiency, neither in patients with normal coronary arteries, nor in patients with coronary artery disease. Furthermore, in patients with acute ischaemic syndromes, ventricular asynchrony exerts a neutral effect on the ischaemic myocardium. Cardiac resynchronization therapy improves left ventricular systolic and diastolic function without an increase in myocardial oxygen consumption or energy cost. This therapy may decrease the inhomogeneity in regional oxidative metabolism, myocardial perfusion and cardiac efficiency. Further experimental and clinical studies are needed on this area.