Pedro Iturralde

Long-term efficacy of low doses of quinidine on malignant arrhythmias in Brugada syndrome with an implantable cardioverter-defibrillator: A case series and literature review

BACKGROUND To prevent the recurrence of ventricular arrhythmias (VA) in Brugada syndrome (BrS), only quinidine has been consistently reported to have a beneficial effect. Recommended doses are ≥ 1 g/d. The efficacy of lower doses of quinidine has been suggested on the basis of a few isolated experiences. OBJECTIVES To describe the efficacy and safety of doses ≤ 600 mg/d of quinidine after cardioverter-defibrillator implantation in BrS at 2 referral centers and to compare those results with a comprehensive review of the literature. METHODS In a retrospective analysis of medical records from the 2 centers, 6 men with BrS who received ≤ 600 mg/d of quinidine sulfate or hydroquinidine after cardioverter-defibrillator implantation were identified. Quinidine was initiated after arrhythmic syncope or appropriate shocks, including arrhythmic storm in 4. A literature search was performed to find previous cases with symptomatic BrS reported as having received ≤ 600 mg/d of quinidine. RESULTS Quinidine prevented recurrence of VA in all patients from our series without side effects during a median follow-up of 4 years (from 2 to 8 years). In the literature review, 14 additional adults were found. With the exception of 3, quinidine effectively suppressed arrhythmic events in all of them. Four subjects who discontinued the medication experienced VA recurrence, successfully treated by restarting quinidine. CONCLUSIONS Low doses of quinidine were well tolerated and effective to prevent the recurrence of VA, including arrhythmic storm, in subjects with BrS with an implantable cardioverter-defibrillator. Effectiveness of quinidine or hydroquinidine in doses ≤ 600 mg/d is 85%.

Influence of infarct-related artery patency on the indexes of parasympathetic activity and prevalence of late potentials in survivors of acute myocardial infarction

OBJECTIVES The purpose of this study was to determine whether infarct-related coronary artery patency influences myocardial electrical stability as measured by the prevalence of late potentials or heart rate variability. BACKGROUND Several studies have suggested that loss of vagal activity is associated with an increased incidence of arrhythmic death after myocardial infarction. METHODS A short-duration, high resolution electrocardiogram (ECG) was performed before hospital discharge in 175 patients with a first myocardial infarction. Seventy-three patients received thrombolytic therapy. All patients underwent coronary angiography. Coronary occlusion was defined as minimal or no anterograde flow. Eighty-eight patients (50.3%) had an occluded infarct-related artery. Sixty-two healthy subjects served as control subjects to determine the normal range of heart rate variability. RESULTS Comparison between the control group and patients without patency of the infarct-related artery in the time domain and spectral analyses revealed in the latter patients a reduced heart rate variability (p < 0.0001) and a lower power spectrum density in both the 0.05- to 0.15-Hz band (p < 0.0001) and the 0.15- to 0.35-Hz band (p < 0.0001). The heart rate variability in patients with late potentials was lower than in those with a normal signal-averaged ECG. Those patients with spontaneous or thrombolysis-induced reperfusion have less occurrence of late potentials and higher parasympathetic activity than do patients with a closed artery. CONCLUSIONS This study suggests that the patency of the infarct-related artery determines both the absence of late potentials and the preservation of vagal tone and may explain the reduction in mortality induced by thrombolytic therapy in myocardial infarction.

Successful Radiofrequency Ablation of an Accessory Pathway During Pregnancy

The preexcitation syndrome is a rare entity during pregnancy. We present a 20‐week pregnant patient with Wolff‐Parkinson‐White syndrome and recurrent episodes of tachycardia with hemodynamic compromise refractory to medical treatment that required electrical cardioversion several times. Due to the poor evolution we performed a successful radiofrequency ablation of a right posteroseptal accessory pathway using 70 seconds of total fluoroscopy time without complications. We consider this is an alternative and safer treatment in those cases in which the tachyarrhythmias compromise the hemodynamic state during pregnancy.

A new ECG algorithm for the localization of accessory pathways using only the polarity of the QRS complex

A new algorithm is proposed for localization of accessory atrioventricular pathways by use of a 12-lead electrocardiogram (ECG). The polarity of the QRS complex in leads III, V1, and V2 from 102 patients with Wolff-Parkinson-White syndrome with manifested preexcitation who underwent successful radiofrequency catheter ablation was analyzed. Accessory pathways on the right side of the heart were localized to three regions around the tricuspid annulus, and left-sided pathways were localized to two regions around the mitral valve annulus. In 42 of 46 patients (91%) with left posterolateral accessory pathways, a common characteristic of the ECG was a positive QRS complex in leads III and V1 (sensitivity 91%, specificity 95%). Of 19 patients with left inferior paraseptal or inferior accessory pathways, 16 (84%) had a negative QRS complex in lead III and a positive QRS complex in lead V1 (sensitivity 84%, specificity 98%). All six patients with right anterosuperior paraseptal accessory pathways had a positive QRS complex in lead III but a negative QRS complex in lead V1 (sensitivity 100%, specificity 97%). The 25 patients with right inferior paraseptal or inferior accessory pathways had a negative or isodiphasic QRS complex in leads III and V1, but the QRS complex was positive in lead V2 in 21 (84%) of these patients (sensitivity 84%, specificity 100%). Finally, five of the six patients (83%) with right anterior accessory pathways had a negative QRS complex in leads III, V1, and V2 (sensitivity 83%, specificity 96%). With the algorithm, the localization of accessory pathways was thus identified in 90 of the 102 patients (88%).

Arrhythmic storm responsive to quinidine in a patient with Brugada syndrome and vasovagal syncope

A 37‐year‐old man with Brugada syndrome (BrS) and arrhythmic storm is described. One month after implantation of a cardioverter‐defibrillator he presented with recurrent appropriate shocks for spontaneous ventricular fibrillation (VF). Because of this arrhythmic storm, quinidine therapy was initiated with total suppression of all spontaneous arrhythmias. He had remained free of arrhythmias for 22 months since quinidine initiation. Two episodes of VF occurred after the patient stopped taking the medication. The patient resumed quinidine and has been free of VF for the last 3 months. This response to quinidine in a patient with symptomatic BrS supports its role in the prophylaxis of arrhythmic events in BrS.

Reuse of Pacemakers Comparison of Short and Long-term Performance

Background— In developing economies, there are patients in whom pacemaker implantation is delayed because they cannot afford one. Reused devices have been a solution. To address concerns about safety, a cohort of consecutive patients implanted with a reused pacemaker was compared with a control group. Methods and Results— A cohort of 603 consecutive patients from 2000 to 2010 was studied in an ambispective noninferiority study. The study group patients (n=307) received resterilized pacemakers, and the control group patients (n=296) received a new pacemaker. A combined end point of 3 major outcomes–unexpected battery depletion, infection, and device dysfunction–was analyzed. A total of 85 pacemakers had to be explanted, 31 in the control group (10.5%) and 54 in the study group (17.6%; relative risk, 1.68; 95% confidence interval, 1.1–2.5; P =0.02). Forty-three reached the primary end point, 16 in the control group (5.5%) and 27 in the study group (7.2%; relative risk, 1.3; 95% confidence interval, 0.70–2.45; P =0.794). In terms of individual outcomes, 5 new pacemakers (1.7%) and 11 resterilized pacemakers (3.6%) had unexpected battery depletion (relative risk, 2.12; 95% confidence interval, 0.75–6; P =0.116); 3.7% new pacemakers and 3.2% reused pacemakers had a procedure-related infection (relative risk, 0.87; 95% confidence interval, 0.38–2.03; P =0.46); and 1 pacemaker in the study group malfunctioned. Conclusions— Pacemaker reuse is feasible and safe and is a viable option for patient with bradyarrhythmias. Other than the expected shorter battery life, reuse of pacemaker generators is not inferior to the use of new devices. # Clinical Perspective {#article-title-25}Background— In developing economies, there are patients in whom pacemaker implantation is delayed because they cannot afford one. Reused devices have been a solution. To address concerns about safety, a cohort of consecutive patients implanted with a reused pacemaker was compared with a control group. Methods and Results— A cohort of 603 consecutive patients from 2000 to 2010 was studied in an ambispective noninferiority study. The study group patients (n=307) received resterilized pacemakers, and the control group patients (n=296) received a new pacemaker. A combined end point of 3 major outcomes–unexpected battery depletion, infection, and device dysfunction–was analyzed. A total of 85 pacemakers had to be explanted, 31 in the control group (10.5%) and 54 in the study group (17.6%; relative risk, 1.68; 95% confidence interval, 1.1–2.5; P=0.02). Forty-three reached the primary end point, 16 in the control group (5.5%) and 27 in the study group (7.2%; relative risk, 1.3; 95% confidence interval, 0.70–2.45; P=0.794). In terms of individual outcomes, 5 new pacemakers (1.7%) and 11 resterilized pacemakers (3.6%) had unexpected battery depletion (relative risk, 2.12; 95% confidence interval, 0.75–6; P=0.116); 3.7% new pacemakers and 3.2% reused pacemakers had a procedure-related infection (relative risk, 0.87; 95% confidence interval, 0.38–2.03; P=0.46); and 1 pacemaker in the study group malfunctioned. Conclusions— Pacemaker reuse is feasible and safe and is a viable option for patient with bradyarrhythmias. Other than the expected shorter battery life, reuse of pacemaker generators is not inferior to the use of new devices.

Radiofrequency catheter ablation for the treatment of supraventricular tachycardias in children and adolescents

We report our experience in radiofrequency catheter ablation between April, 1992 and December, 1998, in which we treated 287 patients less than 18 years of age (mean 14.3 +/- 3.1 years) with supraventricular tachycardia. Accessory, pathways were the arrhythmic substrate in 252 of the patients (87.8%), the patients having a total of 265 accessory pathways. Atrioventricular nodal re-entry was the cause of tachycardia in 26 patients (9.0%), while atrial flutter was detected in the remaining 9 patients (3.1%). We were able successfully to eliminate the accessory pathway in 236 patients (89%), but 25 patients had recurrent arrhythmias. Ablation proved successful in all cases of atrioventricular node re-entry tachycardia, the slow pathway being ablated in 25 patients, and the fast pathway in only one case. Recurrence of the arrhythmia occurred in three patients (11.5%). We performed a second ablation in these children, all then proving successful. The ablation was successful in all cases of atrial flutter, with one recurrence (11.1%). Overall, therefore, ablation was immediately successful in 271 patients (94.4%), with a recurrence of the arrhythmia in 29 cases (10.7%). The incidence of serious complications was 2.09%. There was one late death due to infective endocarditis, 3 patients suffered complete heart block, 1 had mild mitral regurgitation, and 1 patient developed an haematoma in the groin. We conclude that radiofrequency catheter ablation can now be considered a standard option for the management of paroxysmal supraventricular tachycardias in children and young adults.

Device-detected subclinical atrial tachyarrhythmias: definition, implications and management—an European Heart Rhythm Association (EHRA) consensus document, endorsed by Heart Rhythm Society (HRS), Asia Pacific Heart Rhythm Society (APHRS) and Sociedad Latinoamericana de Estimulación Cardíaca y Electrofisiología (SOLEACE)

Among atrial tachyarrhythmias (AT), atrial fibrillation (AF) is the most common sustained arrhythmia. Many patients with AT have no symptoms during brief or even extended periods of the arrhythmia, making detection in patients at risk for stroke challenging. Subclinical atrial tachyarrhythmia and asymptomatic or silent atrial tachyarrhythmia often precede the development of clinical AF. Clinical AF and subclinical atrial fibrillation (SCAF) are associated with an increased risk of thromboembolism. Indeed, in many cases, SCAF is discovered only after complications such as ischaemic stroke or congestive heart failure have occurred

Peripheral Heart Blocks Associated with Myocardial Infarcts: Clinical Diagnosis Based on Experimental Findings

Septal necrosis + peripheral left blocks. Because of an extensive septal necrosis, the manifestation of the initial ventricular activation forces decreases in the precordial leads. With left bifascicular block (LASB + LPSB), the first ventricular activation forces become more evident and the electrical signs of septal necrosis can be concealed. In the presence of a trifascicular block, manifestation of the first ventricular electromotive forces diminishes again and the electrical signs of septal necrosis become evident once more. Small Q waves are present in leads V1 to V4. Extensive anterior necrosis + peripheral blocks. This necrosis is manifested by QS complexes from V2 to V6. An associated left bifascicular block reduces the electrical manifestation of dead tissue: QS complexes persist only in V3 and V4. In turn, a coexisting trifascicular block causes the presence of QS complexes from V2 to V5. Posteroinferior necrosis + peripheral blocks. Electromotive forces of the ventricular activation shift upward, due to a posteroinferior necrosis and QS or QR complexes are recorded in leads aVF, II and III. An associated left bifascicular block displaces the main electromotive forces downward, posteriorly and to the left, due to a delay of the posteroinferior activation fronts. The ventricular complexes become positive and wider in all leads, reflecting the potential variations of the inferior portions of the left ventricle: aVF, II, III, sometimes V5 and V6. Consequently, the electrical signs of necrosis are reduced or abolished. Due to a trifascicular block, wide and slurred QS complexes are recorded in aVF, II, III and sometimes in V5 and V6.

Cardiac Involvement in Kearns-Sayre Syndrome

The mitochondrial cytopathies or oxidative-phosphorylation diseases are a diverse group of disorders that result from the structural, biochemical, or genetic derangement of mitochondria. Because mitochondrial dysfunction can affect the most highly energy-dependent organs, cardiac involvement is frequent in these diseases. To identify the clinical features of Kearns-Sayre syndrome, an entity associated with this group of diseases, we evaluated cardiac structure and function in 5 patients with Kearns-Sayre syndrome and followed the clinical course of these patients for 5 years.