Geert-Jan Kimman

Biphasic response to dobutamine predicts improvement of global left ventricular function after surgical revascularization in patients with stable coronary artery disease: Implications of time course of recovery on diagnostic accuracy

OBJECTIVES This study sought to evaluate the time course of improvement of left ventricular (LV) dysfunction in stable patients and its implications on the accuracy of dobutamine echocardiography for predicting improvement after surgical revascularization. BACKGROUND Little is known about the optimal timing for evaluation of postrevascularization recovery of the contractile function of viable myocardium. METHODS Sixty-one patients with chronic ischemic LV dysfunction scheduled for elective surgical revascularization were prospectively selected. They underwent dobutamine echocardiography (5 to 40 microg/kg body weight per min) and radionuclide ventriculography both preoperatively and at 3-month follow-up. At 14 months, another evaluation of LV function was obtained. To analyze echocardiograms, a 16-segment model and a five-point scoring system were used. Dyssynergic segments were considered likely to recover in the presence of a biphasic contractile response to dobutamine. Improvement of global function was defined as a > or =5% increase in LV ejection fraction (LVEF). RESULTS Of the 61 patients, LVEF improved in 12 at 3 months and in 19 at late follow-up (from 32+/-8% to 42+/-9%, p < 0.0001). The frequency and time course of improvement of LVEF were similar in patients with mild and severe LV dysfunction. A biphasic response, identified in 186 of the 537 dyssynergic segments, was predictive of recovery in 63% at 3 months and in 75% at late follow-up. The positive predictive value was best in the most severe dyssynergic segments (90% vs. 67%). Other responses were highly predictive for nonrecovery (92%). The sensitivity and specificity for improvement of global function on a patient basis (> or =4 biphasic segments) were 89% and 81%, respectively, at late follow-up. CONCLUSIONS Serial postoperative follow-up studies demonstrate incomplete recovery of contractile function at 3 months. The diagnostic accuracy of dobutamine echocardiography for predicting recovery is dependent on three factors: the combining of low and high dobutamine dosages, the severity of regional dyssynergy and the timing of evaluation.

Transseptal left heart catheterisation guided by intracardiac echocardiography

OBJECTIVE To develop a novel approach of transseptal puncture guided by intracardiac echocardiography and to assess its efficacy. METHODS Transcatheter intracardiac echocardiography with a 9 MHz rotating transducer was performed to guide transseptal puncture in 12 patients (mean age 43.1 years, range 31–68) who underwent radiofrequency catheter ablation of left sided accessory pathways. Initially, the echocardiography and transseptal catheters were placed adjacent to each other in the superior vena cava and were withdrawn to the level of the fossa ovalis. RESULTS The successful puncture site was associated with visualisation of the fossa ovalis (12 patients, 100%) and the aorta (12 patients, 100%), tenting of the fossa (six patients, 50%), penetration of the needle visualised by the ultrasound catheter (12 patients, 100 %), and echocardiographic contrast material applied in the left atrium (12 patients, 100%). The characteristic jump of the needle onto the fossa ovalis was observed simultaneously with fluoroscopy and intracardiac ultrasound (12 patients, 100%). All procedures were successful. There were no complications associated with the transseptal procedure. CONCLUSIONS Intracardiac echocardiography is feasible to guide transseptal puncture. The optimal puncture site can be assessed by simultaneous detection of the characteristic downward jump of the transseptal needle onto the fossa ovalis by intracardiac ultrasound and fluoroscopy.

Comparison of radiofrequency versus cryothermy catheter ablation of septal accessory pathways

Approximately 30% of all accessory pathways are located in the “septal” area. As these pathways are close to the atrioventricular node, there is an increased risk of right bundle branch block or inadvertent complete atrioventricular block during catheter ablation.1 Lesions created by radiofrequency (RF) energy inevitably involve some degree of tissue disruption and are irreversible. As cryothermy energy has the ability to reversibly show loss of function of tissue with cooling (“ice mapping”) at less negative temperatures, and progressive ice formation at the catheter tip causes adherence to the adjacent tissue, this ablation method potentially has advantages over RF for safe ablation of septal accessory pathways.2–4 In this retrospective study we compare transvenous RF with cryoablation in patients with septal accessory pathways. Between January 2000 and October 2001, 15 patients were treated with RF and the next consecutive nine patients with cryoablation for septally located accessory pathways. The final classification of the accessory pathways was made according to the successful ablation site on fluoroscopy. A standard electrophysiological study was performed and, after confirmation of the presence of an accessory pathway, transvenous RF or cryoablation was carried out. Mapping was performed beginning at the anteroseptal region at the His deflection down to the coronary os and further to the right posterior region. For both energy forms standard techniques were used to identify prospective ablation sites. For cryoenergy procedures, initially ice mapping was done by cooling to −30°C for a maximum of 80 seconds with the use of a 7 French cryocatheter (Freezor, curve 3, CryoCath Technologies Inc, Montreal, Quebec, Canada). …

Ten Year Follow‐Up After Radiofrequency Catheter Ablation for Atrioventricular Nodal Reentrant Tachycardia in the Early Days Forever Cured, or a Source for New Arrhythmias?

Background: Radiofrequency (RF) catheter ablation is highly effective with a low complication rate. However, lesions created by RF energy are irreversible, inhomogeneous, and therefore potentially proarrhythmic.

Transvenous cryothermal catheter ablation of a right anteroseptal accessory pathway

Transvenous Cryothermal Catheter Ablation. In patients with Wolff‐Parkinson‐White syndrome, right anteroseptal accessory pathways are uncommon and run from the atrium to the ventricle in close anatomic proximity to the normal AV conduction system. Radiofrequency catheter ablation is the first‐line therapy for elimination of these accessory pathways. Although the initial success rate is high, there is a potential risk of inadvertent development of complete heart block, and the recurrence rate is relatively high. The capability of cryothermal energy to create reversible lesions (ice mapping) at less severe temperatures provides a potential benefit in ablation of pathways located in a complex anatomic area, such as the mid‐septum and anteroseptum.

Transthoracic defibrillation of short-lasting ventricular fibrillation: a randomised trial for comparison of the efficacy of low-energy biphasic rectilinear and monophasic damped sine shocks.

Background — Biphasic rectilinear shocks are more effective than monophasic shocks for transthoracic atrial defibrillation and for ventricular arrhythmias during electrophysiological testing.We undertook the present study to compare the efficacy of 100 J rectilinear biphasic waveform shocks with 150 J monophasic damped sine waveform shocks for transthoracic defibrillation of true ventricular fibrillation during defibrillation threshold testing (DFT).The second aim of the study was to analyse the influence of patch positions on the efficacy of defibrillation. Methods — 50 episodes of 14 patients (age ranging from 37 to 82 years) who underwent DFT testing were randomised for back-up shocks with either a sequence of 100 and 200 J biphasic waveform, or a sequence of 150 and 360 J conventional monophasic shocks. A binary search protocol was used at implantation and before hospital discharge. Patients were also randomised to an anteroposterior position versus a right-anterior-apical position. A crossover was performed between implantation and pre-hospital discharge for biphasic versus monophasic sequence as well as for the 2 different positions. Results — After failed internal shocks, 27 episodes were treated with biphasic, and 23 with monophasic shocks. The first attempt by the external device did not terminate 11 episodes (2 biphasic, 9 monophasic).The first shock efficacy was significantly greater with biphasic than with monophasic shocks (p > 0.02). The overall success rate was 93% with biphasic shocks and 64% with monophasic shocks. In multivariate regression analysis including patch position, arrhythmia duration, type of waveform, testing order and session, only waveform was associated with successful defibrillation (p>0.02). Conclusion — For transthoracic defibrillation of ventricular fibrillation, low-energy rectilinear biphasic shocks are more effective than monophasic shocks.The position of the defibrillation shock pads has no influence on the biphasic shock efficacy, but anteroposterior pad position is more effective using monophasic shocks.

Effects of Septal Pacing on P Wave Characteristics: The Value of Three‐Dimensional Echocardiography

SZILI‐TOROK, T., et al.: Effects of Septal Pacing on P Wave Characteristics: The Value of Three‐Dimensional Echocardiography. Interatrial septum (IAS) pacing has been proposed for the prevention of paroxysmal atrial fibrillation. IAS pacing is usually guided by fluoroscopy and P wave analysis. The authors have developed a new approach for IAS pacing using intracardiac echocardiography (ICE), and examined its effects on P wave characteristics. Cross‐sectional images are acquired during pullback of the ICE transducer from the superior vena cava into the inferior vena cava by an electrocardiogram‐ and respiration‐gated technique. The right atrium and IAS are then three‐dimensionally reconstructed, and the desired pacing site is selected. After lead placement and electrical testing, another three‐dimensional reconstruction is performed to verify the final lead position. The study included 14 patients. IAS pacing was achieved at seven suprafossal (SF) and seven infrafossal (IF) lead locations, all confirmed by three‐dimensional imaging. IAS pacing resulted in a significant reduction of P wave duration as compared to sinus rhythm ( 99.7 ± 18.7 vs 140.4 ± 8.8  ms; P < 0.01 ). SF pacing was associated with a greater reduction of P wave duration than IF pacing ( 56.1 ± 9.9 vs 30.2 ± 13.6  ms; P < 0.01 ). P wave dispersion remained unchanged during septal pacing as compared to sinus rhythm ( 21.4 ± 16.1 vs 13.5 ± 13.9  ms; NS ). Three‐dimensional intracardiac echocardiography can be used to guide IAS pacing. SF pacing was associated with a greater decrease in P wave duration, suggesting that it is a preferable location to decrease interatrial conduction delay. (PACE 2003; 26[Pt. II]:253–256)

Ablation lesions in Koch's triangle assessed by three-dimensional myocardial contrast echocardiography.

BackgroundMyocardial contrast echocardiography (MCE) allows visualization of radiofrequency (RF) ablation lesions in the left ventricle in an animal model. Aim: To test whether MCE allows visualization of RF and cryo ablation lesions in the human right atrium using three-dimensional echocardiography.Methods18 patients underwent catheter ablation of a supraventricular tachycardia and were included in this prospective single-blind study. Twelve patients were ablated inside Kochs triangle and 6, who served as controls, outside this area. Three-dimensional echocardiography of Kochs triangle was performed before and after the ablation procedure in all patients, using respiration and ECG gated pullback of a 9 MHz ICE transducer, with and without continuous intravenous echocontrast infusion (SonoVue, Bracco). Two independent observers analyzed the data off-line.ResultsMCE identified ablation lesions as a low contrast area within the normal atrial myocardial tissue. Craters on the endocardial surface were seen in 10 (83%) patients after ablation. Lesions were identified in 11 out of 12 patients (92%). None of the control patients were recognized as having been ablated. The confidence score of the independent echo reviewer tended to be higher when the number of applications increased.Conclusions1. MCE allows direct visualization of ablation lesions in the human atrial myocardium. 2. Both RF and cryo energy lesions can be identified using MCE.

An “Atypical” Case of “Typical” AVNRT?

A 62-year-old man developed syncope during bicycle training. At arrival of the ambulance his rhythm was ventricular fibrillation which was terminated by 360-J direct current (DC) shocks. He had no history of any significant cardiac or noncardiac disease and did not take any medication. Echocardiography showed a slightly diminished left ventricular function with an estimated left ventricular ejection fraction of 0.45. During exercise testing sustained fast monomorphic ventricular tachycardia (VT) started and terminated spontaneously. During electrophysiological testing a fast monomorphic VT, cycle length (CL) 202 ms, was easily and reproducibly induced with programmed ventricular stimulation. Its morphology was identical to the one observed during exercise testing. Besides the VT, a regular narrow complex tachycardia was easily and repeatedly induced with ventricular programmed stimulation during electrophysiological testing (Fig. 1). The patient recognized this tachycardia as the source of palpitations during exercise training for at least two decades. Programmed atrial stimulation revealed more than one sudden AH “jump” (>50 ms) with echo cycles. Intravenous administration of 12 mg adenosine resulted in ventriculoatrial (VA) dissociation during ventricular pacing at a 500-ms CL. Retrograde conduction was midline and decremental during programmed ventricular stimulation. The above mentioned findings supported the diagnosis of atrioventricular nodal reentrant tachycardia (AVNRT). Several additional findings were noted. Without obvious alteration of the CL, there was a significant change in the retrograde and in the anterograde activation times. The earliest retrograde activation was observed in the posteroseptal region. This phenomenon was associated with a noticeable alteration on the surface electrocardiograph (ECG). When the retrograde activation was faster, there was no observable retrograde P wave on the surface ECG. The longer retrograde activation time was associated with a negative deflection at the end of the QRS in leads