Alpaslan Birdane

Initiation of Monomorphic Ventricular Tachycardia: Electrophysiological, Clinical Features, and Drug Therapy in Patients With Implantable Defibrillators

At least 2 distinct patterns of sustained monomorphic ventricular tachycardia (MVT) have been ascribed during analysis of stored intracardiac electrograms retrieved from implantable cardioverter defibrillators and Holter recordings in patients with ventricular arrhythmia. We aimed to investigate the electrophysiological features of MVT with different initiation patterns in patients with implantable cardioverter defibrillators and to assess whether there is a relationship of the initiation patterns of sustained MVT with clinical characteristics and efficacy of antiarrhythmic therapy. Seventy-four stored intracardiac electrograms in 21 patients (mean age of 68.2 +/- 4.2 years) with MVT were evaluated. Cardiovascular diagnosis included coronary artery disease in 85.7% of the patients. All MVT episodes were classified as those initiating with ventricular premature beats (nonsudden onset MVT) and those without ventricular ectopy preceding tachycardia (sudden onset MVT). There was significant difference in left ventricular ejection fraction between MVTs with different initiation pattern, being the lower in those with nonsudden onset (33.6% +/- 38.4% vs. 38.4 +/- 7.0%, P <.04). Ventricular tachycardia cycle length was shorter in group of MVT with nonsudden onset as compared with sudden onset (338.5% +/- 48.1% vs. 376.8% +/- 57.0%, P <.02). Tachycardia with sudden onset was associated with shorter preceding RR interval than tachycardia with nonsudden onset (821.8 +/- 136.2% vs. 748.7 +/- 107.7%, P <.01). There were no significant differences in the type of antiarrhythmic drug therapy used between groups (P >.05). Monomorphic ventricular tachycardias with nonsudden onset occurred more frequently than with sudden onset, without precipitating RR cycles shortening, are faster in rate, associating with lower ejection fraction. Monomorphic ventricular tachycardias with sudden onset are characterized by preceding shortening of RR intervals, slower cycle length, and less worsening of ejection fraction.

Fractal scaling of laser Doppler flowmetry time series in patients with essential hypertension

The full diagnostic potential of the fractal complexity measure, α, of detrended fluctuation analysis (DFA) has not been realized yet. To reveal the impaired mechanisms in the blood flow regulation in patients with essential hypertension (EHT), we studied the laser Doppler flowmetry (LDF) time series by applying DFA. Forearm microvascular blood flow was measured by LDF during supine rest. After a 15 min baseline recording, microvascular response to thermal hyperemia was measured over 30 min. We found three distinct scaling regions; corresponding to the integration of local mechanisms, cardiac effect on local blood flow, and the coupling of extrinsic factors (cardiac and respiratory) to local blood flow by myogenic mechanism. In the control group, local scaling exponent, α(L)=0.96 ± 0.08, did not change but cardiac scaling exponent, α(C)=1.53 ± 0.05, for baseline signal was increased to α(CT)=1.73 ± 0.10 and cardio-respiratory scaling exponent, α(CR)=0.73 ± 0.19, was decreased to α(CRT)=0.24 ± 0.06 during vasodilatation in response to local heating. However, we found significantly different scaling exponents, α(LT)<1, α(CT) ≥ α(C)<1.5 and α(CR) ≈ α(CRT)>0.5 in patients with EHT. Our findings suggest that the local regulatory and the cushioning peripheral vascular functions are impaired in patients with EHT, and vascular/microvascular pathology can be evaluated by applying DFA to LDF signal.

P wave amplitude and duration may predict immediate recurrence of atrial fibrillation after internal cardioversion.

Background: Although internal cardioversion (IC) for atrial fibrillation (AF) is effective at restoring sinus rhythm, immediate recurrence (IR) of AF after IC is a major and largely unpredictable clinical problem. The purpose of the study was to determine the role of P wave duration and amplitude in prediction of IR of AF after IC. Forty‐five consecutive patients undergoing IC for chronic AF were evaluated.

Clinical importance of the initiation pattern of monomorphic ventricular tachycardia

We investigated the clinical and electrophysiological features of monomorphic ventricular tachycardia (MVT) with different initiation patterns in patients with implantable cardioverter defibrillator to assess whether there is a relationship between the initiation patterns of sustained MVT and clinical characteristics, and the efficacy of antiarrhythmic and electrical therapy. Fifty-five stored IECGs in twenty-two patients with MVT were evaluated. All MVT episodes were classified as initiating with ventricular premature beats (non-sudden onset MVT) or without ventricular ectopy preceding tachycardia (sudden onset MVT). Non-sudden onset MVT was characterized by shorter tachycardia cycle length (CL) and required higher shock energy for termination. Sudden onset MVT was precipitated by shortening of the sinus CL before tachycardia and was more common with relatively better preserved systolic function.

Cold Exposure and Left Ventricular Diastolic Performance In Coronary Artery Disease

It is known that cold exposure is accompanied by coronary artery vasoconstriction and ischemia in patients with coronary artery disease (CAD). The aim of the present study was to evaluate the response of left ventricular (LV) diastolic and systolic functions, estimated by means of Doppler echocardiography, to cold pressor test (CPT) in patients with CAD. Twenty- five male patients (mean age 50.8 ±8.1 years) with documented CAD underwent CPT with Doppler echocardiographic assessment of LV diastolic and systolic functions. According to the development of ischemic response to CPT, all patients were divided into 2 groups: group 1,10 patients with ischemia and group 2, 15 patients without ischemia during CPT. Cold exposure caused significant increase in blood pressure with no changes in heart rate in all CAD patients. Patients with signs of ischemia during cold exposure had lower transmitral flow velocity during early filling (p < 0.001), prolonged isovolumic relaxation time (p < 0.04), shortened deceleration time of early transmitral flow velocity (p < 0.001), and higher values of Doppler-derived index of myocardial performance (p< 0.0001) than those without ischemic response to CPT. Cold exposure in CAD patients through stimulating of vasoconstriction and ischemia was associated with derangements in LV myocardial performance, manifested by delayed relaxation, impaired stiffness, and reduced contractility.

Value of combination of QT variability and late potentials in identification of patients with ventricular tachycardia after myocardial infarction

and estimation of likelihood ratio (LR) for com- A total of 47 patients with old MI, without signs of parison of dichotomized variables and unpaired stu- bundle branch block and atrial fibrillation, underwent dents t-test for assessment of differences in quantita- arrhythmia evaluation in our clinic and entered the tive variables. study. High-resolution ECG recordings using Kar- Sustained arrhythmia (VT / VF) (Table 2) was diosis ard-LP PC based system, with further analysis found in 68.2% of 22 patients with LP (P,0.003), in of signal-averaged ECG and QT variability were 76.9% of 13 patients with increased QTVI (P,0.009) performed in all patients. The LP were accepted as and in 84.6% of 13 patients with reduced EF (P, positive when the root mean square voltage of the 0.001). Sustained arrhythmia was established in all terminal (40 ms) portion of the filtered QRS complex seven patients having both LP and increased QTVI (RMS40) was ,20 mV and duration of the low- (P,0.002) and in all seven patients with reduced amplitude signal in the terminal filtered QRS com- LVEF and LP (,0.002). When we combined each plex (LAS40) was .38 ms (2). QT variability index arrhythmia marker with LVEF, the LR increased for was calculated due to formula of Atiga et al. (3). LP to 12.8, P,0.0001 and for QTVI to 9.5, P, Patients with clinically documented spontaneous 0.002. Combination of increased QTVI and LP sustained VT / VF (monomorphic VT in 15 and poly- resulted in the rise of LR to 12.8, P,0.0001. morphic VT / VF in six patients) were assigned to Our findings support the opinion that combination of both impaired depolarization and repolarization,

Cardiac biomarkers after internal cardioversion for atrial fibrillation: detection of myocardial injury

Internal electrical cardioversion (IC) of atrial fibrilForty-four patients (mean age was 5967 years, 30 lation (AF) is the most effective method of the sinus females) with chronic AF of various etiology successrhythm (SR) restoration in cases of external defully converted to SR by IC entered the study. fibrillation failure [1]. Despite these, the relatively Internal cardioversion was performed using elecuncertain problem is whether electrical cardioversion trode catheters inserted through the femoral vein. One causes myocardial injury. The problem raised seems of these was positioned in the lower right atrium. A to have practical significance in nowadays when second defibrillation electrode was placed in coronary implantable defibrillators, including atrial one have sinus and an additional catheter was positioned in the gained growing interest and use. right ventricular apex in order to obtain satisfactory R Several studies on external cardioversion of AF wave synchronization and to provide post-shock have established no or small rise in cardiac bioventricular pacing. The shocks were delivered by markers after delivery of shock [2–4]. This was external defibrillator. Starting with a test shock of 1 J attributed to skeletal muscle fractions washout during intensity, the energy was increased in steps until transthoracic shock delivery [2–4]. Recently more cardioversion was achieved (to max. 15 J). specific biomarkers of cardiac injury as troponin T Blood samples for serum levels of cTnT and cTnI, (cTnT) and I (cTnI) have been introduced in clinical CK-MB and myoglobin were drawn before and 2, 4, practice and were found as more sensitive markers of 8 and 24 h after IC. Cardiac troponin T and myoglomyocardial injury during radiofrequency ablation bin levels were measured using radioimmunoassay procedures [5,6]. method and upper laboratory value for cTnT was 0.1 However, whether an IC of AF is accompanied by ng/ml and 76 ng/ml for myoglobin. Cardiac TnI cardiac injury and elevation of biomarkers has not levels were measured using electrochemiluminescent been yet elucidated enough and studies concerning assay (upper laboratory limit 1 ng/ml and cut-off are scanty and controversial. The goal of this study value for myocardial injury was .1.5 ng/ml.). The was assessment of cardiac biomarkers levels as analysis of CK-MB fraction was accomplished using creatin kinase MB (CK-MB), myoglobin and cTnT standard reagents and 24 U/ l were accepted as upper and cTnI after IC for AF. laboratory limit. In 40 of 44 patients IC was successful at mean cumulative cardioversion threshold of 7.663.3 J *Corresponding author. Tel.: 190-222-239-2476; fax: 190-222-225(range 1.0–15) and mean number of shocks 8171. E-mail address: bgorenek@hotmail.com (B. Gorenek). 22.861.8 (range 1–6). Ejection fraction did not

Internal cardioversion of atrial fibrillation under transesophageal echocardiography guidance without fluoroscopy using single-lead catheter technique

disease. A recent report from the Coronary Artery Risk in Young Adults (CARDIA) population indicated that 18% of young black men aged 18 to 30 years had detectable calcium. Among our study participants (all black adults) who were aged 30 years with no history of cocaine use, 36.4% had detectable coronary calcium. Thus, the proportion of young black adults having detectable coronary calcium is much higher in our study than in the CARDIA report. This suggests that some other unmeasured factors merit investigation.

Predictors of immediate recurrence of atrial fibrillation after external cardioversion

Electrocardiographic changes may be helpful in nisms responsible for IRAF following the use of predicting the occurrence of some atrial arrhythmias either of these techniques [5–7]. Immediate reinitia[1]. Despite the large number of studies generated by tion of AF may be one of the factors determining an the interest in understanding the mechanisms underlyunsuccessful electrical cardioversion. However, ining atrial fibrillation (AF), much remains to be formation on clinical and electrocardiographic predicelucidated [2]. Several studies have been undertaken tors of IRAF is very limited. In our hospital, we to assess the clinical and electrophysiological risk investigated the possible predictors of IRAF after factors for AF. For example, in a clinical study that external cardioversion (EC). examined the risk factors for recurrent AF [3], both Ninety-two patients (42 male, mean age 59610 maximum P wave duration and P wave dispersion, in years, 76 with underlying heart disease) undergoing addition to age and a history of cardiac disease, were EC for chronic AF (mean 27618 months) were found to be significant univariate predictors of reevaluated. Twelve lead surface ECGs were recorded current AF. In multivariate analysis, only maximum P continuously before and after EC. The maximum P wave duration and age remained as independent wave duration (P ), the minimum P wave duration max predictors [3]. However, the underlying mechanisms (P ), and the P wave dispersion (P 2P ) were min max min and the clinical risk factors for AF are still not clearly calculated from surface ECG recordings obtained established. during the first minute of successful EC. Electrical cardioversion is an effective way of Eighty patients had successful EC. Twenty patients treating patients with AF. External and intra-atrial (25%) experienced IRAF during the first minute of shocks are given in an attempt to convert AF to sinus SR restoration. In 15 of 20 patients (75%), IRAF was rhythm (SR) with a higher acute success rate of initiated by a short–long–short sequence (SLS) due intra-atrial shocks, but similar long-term recurrence to atrial ectopic beats (AEBs). In these 15 patients, rates of AF [4]. Despite successful conversion of AF the mean coupling interval was 340 ms. Left atrial to SR, the immediate recurrence of AF (IRAF) after dimension (LAD) greater than 60 mm was a strong cardioversion is a major and largely unpredictable predictor of IRAF (P,0.001), with a 4.7-fold greater clinical problem and little is known about the mechalikelihood of recurrence compared to LAD up to 60 mm. Age greater than 65 years was the other strong predictor of IRAF (P,0.01), with a 4.2-fold greater *Corresponding author. Tel.: 190-222-239-2476; fax: 190-222-239likelihood of developing AF recurrence compared to 5370. E-mail address: bgorenek@hotmail.com (B. Gorenek). age less than 65 years. Gender was not an indepen-