Torsade de pointes associated with moxifloxacin: a rare but potentially fatal adverse event.

Torsade de pointes occuring due to a long QT interval is a rare but potentially fatal arrhythmia. Acquired long QT develops most commonly because of drugs that prolong ventricular repolarization. It has been reported that fluoroquinolone antimicrobials prolong the corrected QT interval but rarely cause torsade de pointes. A patient with torsade de pointes risk factors (female sex, advanced age, extreme bradycardia and renal failure) who developed the condition on the fourth day of 400 mg/day of oral moxifloxacin treatment is presented. After the moxifloxacin was stopped, the corrected QT interval normalized and a permanent cardiac pacemaker was implanted. During 11 months of follow-up, arrhythmia did not recur.

Heart rate variability in hypertrophic obstructive cardiomyopathy: association with functional classification and left ventricular outflow gradients.

BACKGROUND: The aim of this study was to investigate cardiac autonomic control in patients with hypertrophic obstructive cardiomyopathy (HOCM) and to assess the indexes of heart rate variability (HRV) in relation to the clinical and echocardiographic features. METHODS AND RESULTS: Twenty-three patients (17 male, six female: mean age 43+/-11) with HOCM and 18 healthy volunteers were included. M-mode and two-dimensional echocardiography, pulsed and continuous-wave Doppler studies were obtained. All patients and volunteers underwent continuous 24-h ambulatory ECG monitoring. Time domain variables considered in this study were standard deviation of mean R-R intervals (SDNN), root mean-squared successive difference (RMSSD) and percentage of cycles differing from the preceding one by more than 50 ms (PNN 50%). Patients were compared to detect associations between indices of heart rate variability, left ventricular outflow tract obstruction and clinical status. Heart rate variability parameters were also correlated with the echocardiographic and clinical characteristics of the patients. Both New York Heart Association (NYHA) functional class I-II patients (group I) and NYHA III-IV patients (group II) had lower values of SDNN, RMSSD and PNN 50% when compared with the control group (P<0.001, P<0.05 and P<0.01, respectively, for group I and P<0.001, P<0.001 and P<0.001, respectively, for group II). Time domain heart rate variability parameters were found to be significantly correlated with the subaortic dynamic obstruction. CONCLUSION: Heart rate variability is reduced in HOCM and well correlated with the degree of subaortic obstruction. Heart rate variability indices are also sensitive markers of the functional status.

Lengthening of intraatrial conduction time in atrial fibrillation and its relation with early recurrence of atrial fibrillation.

Intraatrial conduction delay in atrial fibrillation (AF) that is considered a component of atrial electrical remodeling has been demonstrated previously in experimental models and it is considered an important factor for the induction or stabilization of AF. However, it is not known if this phenomenon exists in human AF. The present study aimed to compare intraatrial conduction time (IACT) in patients with chronic atrial fibrillation who were converted to sinus rhythm and a matched control group, and to investigate its relation with early AF recurrence. Seventeen patients with chronic AF (mean duration of 20.71+/-16.35 months) were enrolled in the study (7 males, 10 females, 63+/-8 years). An age and sex matched control group (n=12) consisted of patients with sinus rhythm who underwent electrophysiological study (EPS). None of the patients were on any antiarrhythmic treatment during the procedures. Cardioversion was performed via external DC cardioversion. Eight patients in the control group were delivered a DC shock because of induced ventricular tachycardia during EPS. IACT was defined as the interval between the onset of P wave surface ECG and the beginning of A wave at high right atrium (IACT 1) and low right atrium (IACT 2). Additionally, the interval between A wave at high right atrium and low right atrium was measured (IACT 3). Patient characteristics such as age, sex and echocardiographic variables were not different between the AF group and the control group. Heart rate after cardioversion was found to be similar between the two groups. Total delivered energy was significantly higher in the AF group than in the control group (464.47+/-165.82 joules vs. 315.00+/-27.77 joules, p<0.001). IACT 1 (15.30+/-7.61 msec vs 8.50+/-5.29 msec, p<0.02 ), IACT 2 (45.25+/-836 msec vs 26.44+/-10.45 msec, p<0.001) and IACT 3 (26.9+/-8.26 msec vs. 18.67+/-10.05, p<0.05) significantly lengthened in the AF group after maintenance of sinus rhythm compared to the control group. There were 6 early AF recurrences during the 1 week follow-up period. Multivariate analysis, revealed IACT 2 and IACT 3 were significantly different between the control group, the patient with recurred AF and the patients with maintained sinus rhythm. Post-hoc analysis revealed that IACT 2 and IACT 3 significantly lengthened in the patients with recurred AF compared to both the control group and patients with maintained sinus rhythm. On the other hand, only IACT 2 patients with maintained sinus rhythm were found to be higher than those of the control group. The present study indicated that intraatrial conduction was disturbed in patients with AF, a finding which is consistent with those of previous experimental studies. Additionally, such a phenomenon may be a risk factor for the early recurrence of AF after cardioversion to sinus rhythm.

Atrial sensing performance of a single-lead VDD pacing system during physical activities.

This study was undertaken to evaluate the atrial sensing performance of a single-lead atrial synchronous-ventricular pacing system during various physical activities on late follow-up. Fourteen patients (mean age 55 +/- 17 years) with a third-degree or high-degree atrioventricular block and normal sinus node function were treated with the single-lead Thera VDD (Medtronic, Inc, Minneapolis, MN) pacemaker system. Mean P-wave amplitude at implantation was 3.2 +/- 1.3 mV. To assess the VDD system performance, P-wave amplitudes during various physical maneuvers (supine, sitting, deep breathing, standing, and exercise; respectively) were measured and atrial sensing was evaluated at a mean follow-up of 11 +/- 4 months. During deep breathing, minimum and maximum P-wave amplitudes (0.8 +/- 0.7, 1.2 +/- 1.0 mV, respectively) were found to be significantly lower than the standing position (minimum, 1.1 +/- 0.9, maximum, 1.4 +/- 1.1 mV P = .02 in both). No significant difference was found during other physical maneuvers. During the testing maneuvers, atrial undersensing was observed in 8 patients (57%) at the nominal atrial sensitivity of 0.5 mV. After increasing the atrial sensitivity (0.25 mV), no sensing failure was observed in these patients. It has been concluded that Medtronic Thera VDD system is a safe and reliable device with an easy implantation technique providing effective atrioventricular synchronization. The sensing problems, which may occur on late follow-up, can be corrected successfully by reprogramming. To achieve an optimal atrial sensing function in patients with a single-lead VDD pacing, we recommend that the atrial sensing capability should be examined in various physical maneuvers.

Left atrial appendage function in patients with different pacing modes.

Many studies suggest that patients who receive a ventricular pacemaker have a higher incidence of systemic thromboembolism compared to patients receiving a physiological pacemaker. However, the exact mechanism regarding the etiology of thromboembolism remains unclear. We evaluated the left atrial appendage (LAA) functions, using multiplane transesophageal echocardiography (TEE), in patients with different pacing modes. In order to evaluate the ejection fraction (EF), peak emptying (V(E)) and filling (V(F)) flow velocities of the LAA by TEE, we studied 31 patients (mean age 63+/-18.5 years) who had been paced for 5.0+/-2.9 years. Patients with atrial fibrillation, left ventricular dysfunction and mitral valve disease were excluded. The pacing indications were complete atrioventricular block (AVB) in 19 patients (9 VVI, 10 VDD or DDD) and sick sinus syndrome (SSS) in 12 patients (5 VVI, 7 DDD). Mean EF, V(E) and V(F) of the LAA were significantly lower in all patients with ventricular pacing (25.5+/-15.6%, 30.4+/-15.6 cm/s and 29. 1+/-19.2 cm/s, respectively) compared to those with physiologic pacing (48.5+/-16.9%, 59.6+/-16.3 cm/s, 57.9+/-18.5 cm/s, respectively) (P<0.01 in all). When patients were further classified with respect to underlying heart disease whether they had SSS or AVB, all measurements of the LAA (EF, V(E) and V(F)) in both subgroup of patients with SSS and AVB were found significantly lower in those with ventricular pacing than in those with physiologic pacing (Tables 3 and 4). This decrease, especially in LAA flow, was much greater in those with SSS (Mean V(E) and V(F) <20 cm/s). In a patient paced with VVI for SSS, a thrombus was detected within the LAA cavity. In conclusion, these results suggest that the pacing modality appeared to influence the LAA functions in paced patients. Patients with asynchronous ventricular pacing modes had a significantly higher incidence of depressed LAA functions than did patients with physiological pacing, especially more marked in patients with sick sinus syndrome. This may be a factor responsible for increased risk of thrombus formation and thromboembolic events in this patient population.

Value of ST-segment depression during paroxysmal supraventricular tachycardia in the diagnosis of coronary artery disease.

We evaluated 39 patients >45 years old with paroxysmal supraventricular tachycardia (SVT), 21 of whom had ST-segment depression during SVT. Treadmill exercise testing, including thallium stress scintigraphy, was performed in all patients and coronary angiography in 21 patients with ST-segment depression. Based on the presence of abnormal findings on exercise electrocardiogram and/or thallium in 7 of 21 patients (33%) with ST-segment depression, with additional corroboration by angiographic data, we conclude that myocardial ischemia and coronary artery disease is one, but not the only, mechanism involved in the genesis of ST-segment depression during paroxysmal SVT.

Congenital complete atrioventricular block in an infant with long QT syndrome.

A three months old patient with congenital complete atrioventricular block and prolonged QT interval syndrome is presented. Before admission she had had two syncopal attacks. During hospitalization she had an episode of torsade de pointes which was followed by ventricular fibrillation. After a successful cardiopulmonary resuscitation, a permanent epicardial ventricular pacemaker was implanted and she was discharged on propranolol therapy. She is now free of symptoms and doing well, 16 months after discharge.

Undersensing of the tiny QRS complexes that emerged after the isolation of the right ventricle in a patient with ventricular tachycardia.

This article describes a patient who underwent right ventricular disconnection for medically refractory ventricular tachycardia associated with arrhythmogenic right ventricular dysplasia. After the operation there was no ventricular tachycardia recurrence. Two years after the operation, he received a permanent VVI pacemaker for the symptomatic second-degree AV block. Sensing function of the pacemaker was normal for the normal QRS complexes, but the tiny QRS complexes that appeared after the arrhythmia surgery were not sensed by the pacemaker and therefore caused no problem.

Importance of notching and slurring of the resting QRS complex in the diagnosis of coronary artery disease.

Data on the correlation of coronary artery disease (CAD) and electrocardiographic findings are, except for Q waves, still controversial. The purpose of this study was to determine whether QRS complex notching and slurring (N&S) is of significant value as a diagnostic discriminator in the detection of CAD. This study comprised 500 consecutive patients aged between 24 and 81 years (mean, 53.4 years) who underwent coronary angiography because of chest pain. Patients were evaluated for CAD, angiographic evidence of myocardial infarction (MI), N&S, and abnormal Q waves. Of these 500 patients, 418 had CAD, and 370 of these had significant (> or = 70%) coronary artery obstruction. The remaining 82 patients had normal coronary arteries. The data revealed that the distribution of N&S in the patients with or without CAD was similar in both the inferior and limb leads (P > .05). But the percentage of N&S in more than two contiguous limb leads was higher in the patients with CAD than in the patients without CAD. Notching and slurring in at least one limb lead was found to be of no value in the diagnosis of MI, of wall motion abnormalities, and of significant obstruction. Notching and slurring in the anterior leads is more sensitive but less specific than abnormal Q waves in the same leads in the detection of significant obstruction, anterior MI, and anterior wall motion abnormalities. Notching and slurring in the anterior leads has as much importance as abnormal anterior Q waves in the detection of angiographic evidence of anterior infarct, of anterior wall motion abnormalities, and of significant coronary artery obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of a new rate adaptive ventricular pacemaker controlled by double sensors.

UNLABELLED: The LEGEND-PLUS, a new rate adaptive pacemaker that combines activity and minute ventilation sensing for automatic rate adaptation was implanted in the right ventricle (VVIR) in 11 patients (mean age 62 +/- 9 years). Initial programming was performed using the Programmer Exercise Protocol (a 3-minute walk). This programming was evaluated by treadmill tests, up-stairs and down-stairs walking, and Holter recordings. RESULTS: Following the final programming of LEGEND-PLUS, the mean upper activity rate was 102 +/- 7 beats/min (range 90-120 beats/min), while the mean upper minute ventilation rate was 125 +/- 16 beats/min (range 100-150 beats/min). The mean rate responses during the exercise protocol and the final programming in minute ventilation and activity sensing modes were 5.4 +/- 2.3 (range 1-9), versus 4 +/- 2.4 (range 1-8; P < 0.01) and 7.6 +/- 1.1 (range 5-9), versus 7.5 +/- 0.8 (range 6-9; P = 0.8), respectively. In the combined sensing mode, the acceleration rate was identical to the activity rate response and the deceleration rate mimicked the minute ventilation. CONCLUSION: Dual sensor VVIR pacemakers have the potential to improve rate adaptation to exercise. The rate response to exercise in patients fitted with activity and minute ventilation sensors, VVIR pacemakers closely mimics the physiological rate response.

Cardioinhibitory response to carotid sinus massage in patients with coronary artery disease.

The relationship between cardioinhibitory response to the carotid sinus massage and the severity of coronary artery lesions and left ventricular impairment was investigated in 86 patients who underwent coronary angiography. The study group (Group 1) comprised 63 patients who had coronary lesions and the control group (Group 2) comprised 23 patients who had normal coronary arteries. There was no significant relationship between the severity of coronary artery lesions and the cardioinhibitory response to the carotid sinus massage in the study group. However, there was a positive correlation (r = 0.478, P < 0.01) between total left ventricular segment scores and the maximal change in RR interval (%) during the right carotid sinus massage in the study group. During the right carotid sinus massage, maximal change of RR interval (%) was significantly higher in patients who had segmental wall motion abnormalities than in patients who did not (83.0 +/- 72.4% vs. 32.9 +/- 42.5%, P < 0.01, respectively). In the patients who could have echocardiographic measurements there was negative correlation between fractional shortening value and maximal change of RR interval (%) (right massage; r = -0.482, P < 0.01, left massage; r = -0.334, P < 0.05). In conclusion, we found a significant relationship between the cardioinhibitory response to carotid sinus massage and the presence and severity of the segmental wall motion abnormalities and left ventricular impairment in patients with coronary artery disease.

The role of arrhythmia and left ventricular dysfunction in patients with acute myocardial infarction and bundle branch block.

To determine the immediate and remote prognostic significance of bundle branch block (BBB) associated with acute myocardial infarction (AMI), 40 patients with AMI and BBB were studied. One hundred forty-four patients with AMI but without BBB were evaluated during the in-hospital phase and 45 of them were taken as a control group. These patients were followed for an average of 15 months (3-28 months). Arrhythmias and left ventricular function were investigated with 24-hr Holter monitoring and echocardiography, respectively. The hospital mortality was significantly greater in patients with BBB than in the control group (32.5% vs 10.4%, p < 0.001). The main cause of mortality was pump failure in the group with BBB (76.9%) and ventricular fibrillation in the control group (53.3%). The peak creatine kinase level was significantly higher in the group with BBB than in the control group (2094.8 +/- 288.4 IU/L vs 416.7 +/- 30.5 IU/L, p < 0.001). In patients with BBB prophylactic temporary pacemaker insertion was not found to improve the hospital mortality rate. In the hospital phase, although 32% of the patients with BBB had complicated arrhythmias (multiform, paired VPB, runs, R-on-T) the cause of death in 10 of the 13 patients who died was pump failure but not arrhythmia. In patients with BBB the wall motion index and the number of patients who had a left ventricular aneurysm were greater than in patients without BBB (9.5 +/- 0.9 vs 6.3 +/- 0.6, p < 0.01 and 52.0% vs 14.3%, p < 0.01, respectively). In patients with BBB follow-up mortality (12.0%) was lower than hospital mortality (32.5%). During the follow-up period there was no significant difference between patients with BBB and those without with regard to complicated arrhythmias (14.8% vs 15.6%). These results indicate that the main cause of poor prognosis during the hospital period in patients with AMI and BBB was not arrhythmia or conduction disturbance but severe pump failure due to extensive myocardial necrosis. Prophylactic temporary pacemaker insertion did not improve the hospital mortality rate of these patients, and patients with AMI and BBB who survive the in-hospital phase after infarction have a good prognosis during the following 15 months.

Is there an effect of amiodarone on the defibrillation threshold?

The interaction between amiodarone and the defibrillation threshold (DFT) is still controversial. We present a case with dilated cardiomyopathy and recurrent sustained monomorphic ventricular tachycardia who received an automatic implantable cardioverter defibrillator (AICD) while under long-term amiodarone treatment. AICD implantation was performed without thoracotomy. The transvenous lead was inserted via a left subclavian vein puncture and the patch was placed on the lateral chest wall, submuscularly. At the time of implantation a 35J shock was not successful in converting ventricular fibrillation to sinus rhythm, but a 40J rescue shock was successful. After discontinuation of amiodarone, DFT measurements were repeated. Sixteen days later DFT was still higher than 34J, but 71 days later it decreased to 20J.