Recurrence of conduction in accessory atrioventricular connections after initially successful radiofrequency catheter ablation

The purpose of this study was to characterize the incidence and clinical features of accessory pathway recurrence after initially successful radiofrequency catheter ablation and to identify variables correlated with recurrence. Radiofrequency ablation was performed with a 7F deflectable tip catheter with a large (4 mm in length) distal electrode. Left-sided accessory pathways were approached through the left ventricle and right-sided pathways by way of the right atrium. Patients were included in the study if 1) they had an initially successful procedure, defined as the absence of accessory pathway conduction immediately after ablation, and 2) had undergone a 3-month follow-up electrophysiologic test or had documented recurrence of accessory pathway conduction. Accessory pathway conduction recurred after initially successful ablation in 16 (12%) of 130 patients. Almost half (7 of 16) of these recurrences were in the 1st 12 h after ablation, and the last occurred after 106 days. Return of delta waves on the electrocardiogram (ECG) or spontaneous paroxysmal supraventricular tachycardia was the initial indication of recurrence in 15 of the 16 patients. Two patients with manifest accessory pathways exhibited recurrence with exclusively concealed accessory pathway conduction. Accessory pathways ablated from the tricuspid anulus (right free wall or septal accessory pathways) had a much higher recurrence rate (24%) than did those on the mitral anulus (6%). Fourteen of 15 patients have had successful repeat accessory pathway ablation after the initial recurrence. After a mean follow-up period of 4 +/- 3 months, there have been no repeat recurrences of any of these accessory pathways. It is concluded that accessory pathway recurrence is infrequent after successful radiofrequency catheter ablation.(ABSTRACT TRUNCATED AT 250 WORDS)

Curative percutaneous catheter ablation using radiofrequency energy for accessory pathways in all locations: results in 100 consecutive patients

Patients with accessory pathway-mediated supraventricular tachycardia have typically been treated with drugs or surgery. Although catheter ablation using high voltage direct current shocks has been used to treat patients with drug-refractory supraventricular tachycardia, there are associated disadvantages, including damage due to barotrauma as well as the need for general anesthesia. Recently, transcatheter radiofrequency energy has evolved as an alternative to direct current shock or surgery to ablate accessory pathways. Percutaneous catheter ablation of 109 accessory pathways with use of radiofrequency energy was attempted in 100 consecutive patients. Patient age ranged from 3 to 67 years. The patients had been treated for recurrent tachycardia with a mean of 2.7 +/- 0.2 antiarrhythmic agents that either proved ineffective or caused unacceptable side effects. In seven patients previous attempts at accessory pathway ablation with use of direct current shock had been unsuccessful. Forty-five (41%) of the pathways were left free wall, 43 (40%) were septal and 21 (19%) were right free wall. Eighty-nine (89%) of the 100 patients had successful radiofrequency ablation at the time of hospital discharge. In all but 12 patients the ablation was accomplished in a single session. Complications attributable to the procedure, but not to the ablation itself, occurred in four patients (4%). No patient developed atrioventricular block or other cardiac arrhythmias. Over a mean follow-up period of 10 months, nine patients had some return of accessory pathway conduction; a repeat ablation procedure was successful in all five patients in whom it was attempted. It is concluded that a catheter ablation procedure using radiofrequency energy can be performed on accessory pathways in all locations. The procedure is effective and safer, less costly and more convenient than cardiac surgery and can be considered as an alternative to lifelong medical therapy in any patient with symptomatic accessory pathway-mediated tachycardia.

Radiofrequency current for catheter ablation of accessory atrioventricular connections in children and adolescents. Emphasis on the single-catheter technique

Catheter ablation of an accessory atrioventricular connection using 500-kHz radiofrequency current was attempted in 10 children and adolescents aged between 6 and 15 years (mean 10.5 years). Six children had the Wolff-Parkinson-White syndrome and four had tachyarrhythmias related to a retrograde-only conducting ("concealed") accessory connection. No child had associated structural heart disease. Symptoms ranged from disabling palpitations to episodes of syncope (three patients) and cardiac arrest (one patient). Ablation was attempted from the left ventricle in all children; in one child, ablation of a second, right-sided pathway was attempted via a right atrial approach. Ten of the 11 accessory connections were interrupted successfully. A single complication was encountered in a 10-year-old girl in whom the procedure had to be terminated because a thrombotic occlusion of the right internal iliac artery had evolved. A simplification of the ablation procedure associated with reduced procedure duration and radiation exposure time was achieved in three children with the Wolff-Parkinson-White syndrome and a left free-wall accessory pathway when a single catheter placed in the left ventricle was used for pathway localization as well as ablation. It is concluded that catheter ablation using radiofrequency current is effective and safe and may supersede surgery as the curative treatment for children with serious symptoms mediated by an accessory atrioventricular connection.

Cardiac arrhythmias and myocardial ischemia after thoracotomy for lung cancer

The records of 598 patients undergoing a thoracic surgical procedure for lung cancer from 1975 through 1989 were reviewed for occurrence of cardiac arrhythmias and myocardial ischemic events. Atrial tachycardias occurred in 16% (94/598); atrial fibrillation was preponderant (87%), followed by supraventricular tachycardia and atrial flutter. Patients with recurrent episodes of dysrhythmias had a significantly higher mortality rate than those without episodes or with a single episode only (17% versus 2.4%; p less than 0.01). Transient ischemic electrocardiographic changes were documented in 23 patients (3.8%) and myocardial infarction in 7 (1.2%). An abnormal preoperative exercise test result and intraoperative hypotension were strongly associated with both dysrhythmia and ischemia (p less than 0.01). Pneumonectomy, ischemic changes on the electrocardiogram, and cardiac enlargement were also associated with arrhythmias (p less than 0.01). A weaker association (p less than 0.05) was found between postoperative arrhythmias and old myocardial infarction (greater than 6 months), arterial hypertension, and heart failure. Pulmonary function had no predictive value in this respect. A history of angina or old myocardial infarction was predictive of transient postoperative myocardial ischemia but not myocardial infarction. Despite improved anesthetic and monitoring techniques and more frequent use of the intensive care unit postoperatively in the last decade, the incidence of arrhythmias after thoracotomy has not decreased. More effective prevention is needed, particularly for patients with defined preoperative and perioperative risk factors.

Early atrial arrhythmias in acute myocardial infarction. Role of the sinus node artery

We studied atrial arrhythmias during the first 12 h of admission to the hospital in 266 consecutive patients with acute myocardial infarction who subsequently underwent coronary angiography. Ten patients developed atrial fibrillation, one atrial flutter, and one supraventricular tachycardia. Another five developed sinus dysrhythmias. All of the above patients had an acute inferior myocardial infarction, and in 10 of the 12 patients with supraventricular arrhythmias and in four of five with sinus dysrhythmias, the origin of the sinus node artery started just after an occluded right coronary or left circumflex artery or was involved in the occlusion. Thus, ischemia of the sinus node due to coronary occlusion proximal to the origin of the sinus node artery was a likely cause of these arrhythmias.

Clinical manifestations and prevalence of different types of supraventricular tachycardia among Chinese

Sixty-nine cases of paroxysmal supraventricular tachycardia (PSVT) were submitted to electrophysiological studies. The prevalence of different types of PSVT is as follows: 49% of the cases had atrioventricular reentry tachycardia (AV-RT), 14.5% atrioventricular nodal reentry tachycardia (AVN-RT), 28% AV + AVN - RT, and 8.5% other types. Altogether 77% in this group had atrioventricular accessory pathway, of which half are concealed pathway. Electrocardiographic characteristics during tachycardia give hints to diagnosis: (1) AV - RT has the fastest heart rate, with 62% 200 BPM or more, and 82% more than 188 BPM; (2) retrograde P waves can be detected in 64% of cases with AV bypass; (3) 50% of AV - RT shows QRS of bundle branch block pattern. Since accessory pathways are present in the majority of PSVT patients in China, the importance of treatment is stressed.

Effect on Ventricular Performance of Direct Current Electrical Shock for Catheter Ablation of the Atrioventricular Junction

In ten patients undergoing catheter ablation of the atrioventricular junction (CAVJ) because of therapy refractoriness of supraventricular arrhythmias, the effect of repeated high energy direct current (DC) shock on left ventricular function has been investigated. End-systolic pressure-volume relation (ESPVR) and the positive first derivative of ventricular pressure (dP/dt) have been used as indices of left ventricular systolic function, while the time constant of isovolumic pressure decay, the diastolic stiffness, and the negative dP/dt represented the diastolic function parameters, respectively. Each patient received at least two and no more than three DC shocks for successful CAVJ, with an energy of 360 joules. Significant acute reduction of both systolic and diastolic function was noted after each DC shock, with a slow partial recovery of both phases. The recovery process involved the systolic phase earlier and more completely than the diastolic one. The alterations observed could not be predicted from preablation values, but were significantly related to cumulative energy dose index for body weight. In conclusion, repeated high energy DC shocks acutely, but reversibly, impair left ventricular function; in addition, the ventricular function reduction is primarily related to the total ablation energy indexed for body weight.

[Different course of myocardial infarction in old age]

For the assessment of the peculiarities of acute myocardial infarction in patients aged over 60 years 100 patients with this disease treated at the Department of Internal and Occupational Diseases, Silesian Medical Academy were compared with 100 patients aged below 60 years. The location of myocardial infarction was similar in both groups. In the younger group premature ventricular beats were more frequent while in the older group supraventricular or ventricular tachycardia and left bundle branch block were more frequent. The death rate was much higher in the older group.

The relationship between ECG signs of atrial infarction and the development of supraventricular arrhythmias in patients with acute myocardial infarction

ECGs obtained on arrival at the hospital from 277 patients with acute myocardial infarction were analyzed retrospectively for PR displacements, which were classified as major or minor criteria for atrial infarction and related to the later occurrence of supraventricular arrhythmia in the hospital. Major criteria were (1) PR segment elevation greater than 0.5 mm in leads V5 and V6 with reciprocal PR segment depression in leads V1 and V2, (2) PR segment elevation greater than 0.5 mm in lead I with reciprocal PR segment depression in leads II and III, and (3) PR segment depression greater than 1.5 mm in precordial leads and greater than 1.2 mm in leads I, II, and III. Abnormal P waves were classified as minor criteria. Major and minor criteria were found in 15 (5.4%) and 19 (6.9%) patients, respectively. Eight (53.3%) patients with major and six (31.6%) with minor criteria had supraventricular arrhythmias, giving odds ratios of 9.9 and 3.7, respectively. Enzyme-estimated infarct size, the occurrence of heart failure, and mortality rates did not differ in patients with or without major criteria for atrial infarction. We conclude that the occurrence of PR segment displacements on the admission ECG may predict the risk of developing supraventricular arrhythmias during hospitalization for myocardial infarction.

[The prospective evolution of the efficacy of antiarrhythmia therapy in paroxysmal supraventricular tachycardia in patients with the ventricular pre-excitation syndrome]

Evolution of the effectiveness of antiarrhythmic drugs used in 240 patients with preexcitation syndrome to arrest episodes of paroxysmal supraventricular tachycardia was analysed prospectively. The first intravenous administration was effective in 97, 93.3, 80.9, 75, 70.3, 60, 48% of cases for novocainamid, verapamil, cordarone, disopyramide, ajmaline, ethacizine, mexitil and inderal, respectively. When observed in prospective evolution for 10-14 years, overall group efficacy dropped from 81.3% at first administration to 21.4%.

Patients with supraventricular tachycardia presenting with aborted sudden death: incidence, mechanism and long-term follow-up

A total of 13 (4.5%) of 290 patients with aborted sudden death had either documented (7; 54%) or strong presumptive evidence of supraventricular tachycardia that deteriorated into ventricular fibrillation. Six (46%) of the 13 had an accessory conduction pathway and either atrial fibrillation (5 patients) or paroxysmal atrioventricular (AV) reentrant tachycardia (1 patient) that deteriorated into ventricular fibrillation. Three patients with AV node reentrant tachycardia and four with atrial fibrillation and enhanced AV node conduction presented with supraventricular arrhythmias that deteriorated into ventricular fibrillation. Patients were treated with medical, surgical or catheter ablative procedures designed to prevent recurrences of supraventricular arrhythmias. Four patients received an implanted automatic defibrillator, but none had an appropriate device discharge. Over a follow-up period of 41.6 +/- 33.6 months, 12 patients are alive without symptomatic arrhythmias. One patient died because of severe chronic lung disease and heart failure. Supraventricular tachycardia was the cause of aborted sudden death in approximately 5% of patients referred for evaluation of sudden cardiac death. Treatment directed at prevention of supraventricular tachycardia was associated with an excellent prognosis. Current treatment techniques appear to obviate the need for automatic defibrillator therapy in these patients.

Sustained supraventricular tachyarrhythmias following coronary artery bypass surgery comparing mammary versus saphenous vein grafts

This retrospective study was designed to determine the incidence of sustained supraventricular tachyarrhythmias (SVTs) in patients undergoing coronary artery bypass grafting (CABG) with internal mammary artery (IMA) grafts, Group A, compared with those with saphenous vein grafts (SVG), Group B. Among 569 consecutive patients who underwent CABG surgery in the same institution, a total of 80 cases from Group A and 80 cases from Group B were selected for this study after application of exclusion criteria. Excluded from this study were the following: patients with preexisting or prior history of SVTs, significant left ventricular dysfunction (ejection fraction less than 40%), postoperative myocardial infarction, drug toxicity or electrolyte imbalance, and advanced chronic obstructive lung disease. Group A consisted of 63 men and 17 women and Group B consisted of 52 men and 28 women. All patients were monitored either in ICU or by telemetry for a period of three to six days after surgery and all had a predischarge 12-lead electrocardiogram. Both groups were fairly comparable in most of their clinical profile and number of grafts. The incidence of SVTs in Group A was 31% (25 of 80 patients) and in Group B was 24% (19 of 80 patients). Furthermore, the incidence of postoperative pericarditis was noted in 35% (28 of 80 patients) of Group A and in 19% (15 of 80 patients) in Group B. The authors conclude that male tobacco smokers of Group A tended to have a significantly higher incidence of postoperative pericarditis with a higher trend for postoperative SVTs than patients from Group B.

Incidence and significance of inducible supraventricular tachyarrhythmias in patients with chronic myocardial infarction

In order to evaluate the incidence and significance of inducible supra-ventricular (SVTA) in patients with chronic myocardial infarction (MI), the results of systematic programmed atrial stimulation were compared in two groups of patients: 150 patients (group I) without MI or underlying heart disease, studied for syncope or conduction disturbances, 296 patients (group II) studied after an acute Mi (greater than 1 month). None of them had spontaneous SVTA, and 24-h Holter monitoring showed no SVTA. The atrial stimulation programme used one and two extra stimuli delivered during sinus rhythm and atrial pacing (600 ms and 10% less than the sinus cycle length). A sustained (S) (greater than 30 s) supraventricular tachycardia (SVT) (atrial flutter, fibrillation, tachycardia) was induced in 17 patients in group I (11%) and in 120 patients in group II (40.5%). In group II inducible SVTA could not be correlated with the occurrence of a SVT during acute MI, the location of MI, the value of LV ejection fraction (EF), the incidence of inducible sustained ventricular tachycardia (VT), or fibrillation (VF). However, inducible SVTA could be correlated with a significantly shorter effective atrial refractory period (197 +/- 23 ms vs 220 +/- 35 ms, P less than 0.001) and a shorter retrograde block cycle length (518 +/- 215 vs 585 +/- 215 ms, P less than 0.03). The patients in group II were followed-up for at least 6 months; 12 of them developed sustained episodes of supraventricular tachycardia; 11 of them had inducible SVTA (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

[Supraventricular tachyarrhythmias during acute myocardial infarction: short- and mid-term clinical significance, therapy and prevention of relapse]

Clinical significance, short and long-term prognostic value, and treatment of supraventricular tachyarrhythmias were evaluated in 208 patients with definite acute myocardial infarction (AMI). No patient received thrombolytic therapy. In Coronary Care Unit supraventricular tachyarrhythmias were detected by continuous electrocardiographic monitoring in 30 (14%) patients: 18 had atrial fibrillation, 1 atrial flutter, 9 paroxysmal atrial tachycardia and 2 non-paroxysmal junctional tachycardia. These episodes began within the first 48 hours of AMI in 93% of patients, and generally they were preceded by frequent or repetitive atrial premature beats. Supraventricular tachyarrhythmias were significantly associated with older age, higher incidence of overt left ventricular dysfunction (both p less than 0.05) and higher Peel Index (p less than 0.02). They caused severe hemodynamic consequences in 20% of patients. In 8 patients they were selflimiting, in 20 they were suppressed by means of medical therapy and in one by DC countershock. During hospitalization supraventricular tachyarrhythmias recurred in one patient; moreover, in this period cardiac death occurred in 26% of patients with supraventricular tachyarrhythmias and in 13% of the remaining (p: ns). Multivariate analysis showed that supraventricular tachyarrhythmias are not important factors in identifying patients at risk of cardiac death. At hospital discharge, patients with supraventricular tachyarrhythmias showed significantly higher values of left ventricular end-diastolic and end-systolic dimensions (both less than 0.05), and a greater use of digitalis-diuretics and/or vasodilators (p less than 0.03). By contrast, in patients with and without supraventricular tachyarrhythmias no significant difference was present with regard to the frequency of New York Heart Association functional classes III-IV for congestive heart failure, frequency of significant tachyarrhythmic events during 24-hour continuous electrocardiographic recording, X-ray cardiac size and left ventricular ejection fraction at rest. In the 2 years following AMI, survival curves showed no significant difference in the risk of cardiac death among patients with or without supraventricular tachyarrhythmias; in particular, in the first group only 2 patients had severe hemodynamic events and no patient showed recurrences of tachyarrhythmia. Our findings suggest that although supraventricular tachyarrhythmias complicating AMI frequently occur in patients with severe cardiac disease they are not related to a higher risk of cardiac death either during in-hospital period or in the 2 years following AMI; medical therapy is effective and safe to suppress these arrhythmias; a systematic use of specific antiarrhythmic drugs to prevent their recurrences is not necessary.

Effect of activity on supraventricular tachyarrhythmias after coronary artery bypass surgery

The purpose of this study was to evaluate patient activities, professional staff activities, backrest position, and diurnal variations as factors that may contribute to the onset of supraventricular tachyarrhythmias (SVT) after coronary artery bypass surgery (CABG). The activities surrounding the recognition of first-onset SVT, as well as preoperative and postoperative data and patient characteristics were examined in 249 patients having CABG. One hundred seventy-three patients qualified for the study; 28% of these patients (n = 49) had SVT. No statistical difference was found between the subjects with SVT and those without SVT when sex, cross-clamp time, creatine kinase peak, hemoglobin and hematocrit levels, and number of bypasses were examined. Patients who had SVT were older than those who did not: 64.8 years for the SVT group versus 60.7 years for the non-SVT group (p less than 0.01). SVT was rare in the first 24 hours after surgery, whereas 60% of the cases occurred during the next 48 hours, without significant diurnal variation: mean time of onset was 11:50 AM. No particular activity of the patient or nurse influenced the onset of SVT during the postoperative period in this group.

Ventricular arrhythmias after correction of ventricular septal defects: importance of surgical approach

To compare the prevalence of conduction disturbances and ventricular arrhythmias in cases of postoperative ventricular septal defect, 100 patients (50 with repair by right atriotomy, group 1; and 50 with repair by right ventriculotomy, group 2) underwent complete evaluation including an electrocardiogram (ECG) and 24 h ambulatory ECG monitoring. The two groups were comparable except for a shorter follow-up duration (7 +/- 3 versus 12.4 +/- 7 years) and a younger age at evaluation (12.4 +/- 5 versus 16.9 +/- 7 years) in group 1. Complete right bundle branch block was less frequent in group 1 than in group 2 (20% versus 50%, p less than 0.05) but three of the four patients with complete atrioventricular (AV) block detected on ambulatory monitoring were in group 1. Six patients had significant supraventricular arrhythmias, all well tolerated. Ambulatory monitoring revealed significant ventricular arrhythmias (modified Lown grade 2 or higher) in 39 patients, with a lower prevalence in group 1 (30% versus 48%, p = 0.05). No correlation was found between prevalence of ventricular arrhythmias and right ventricular systolic pressure, cardiopulmonary bypass duration, presence of a synthetic patch, previous pulmonary artery banding, presence of complete right bundle branch block and cardiomegaly on chest X-ray film. Prevalence of ventricular arrhythmias increased with follow-up duration, age at evaluation and age at surgery. These were always well tolerated and did not warrant treatment. Thus, right atriotomy reduces the prevalence of right bundle branch block but does not prevent late AV block. Ventricular arrhythmias are frequent after surgical closure of ventricular septal defect whatever the surgical approach and their prevalence is not statistically different from that in postoperative tetralogy of Fallot.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac rhythm disturbances early after orthotopic heart transplantation: prevalence and clinical importance of the observed abnormalities

To precisely define the incidence, type and consequences of cardiac arrhythmias early after heart transplantation, 25 cardiac transplant recipients were monitored continuously for 728 days from the day of surgery to discharge or death. A subset of 15 patients had sinus node function studies with overdrive suppression performed weekly at the time of endomyocardial biopsy. Results revealed sinus bradycardia in 10 patients (40%) and junctional bradycardia in 6 (24%). Supraventricular tachycardia in the form of atrial tachycardia, atrial fibrillation and atrial flutter occurred in 11 patients (44%). Ventricular tachycardia occurred in 15 patients (60%) and was nonsustained in all. Cardiac pacing for 1,403 h was used in nine patients with a pulse rate less than 50 beats/min; seven recovered and permanent pacing was instituted in two. In the subgroup that had sinus node function studies, seven patients were identified with clinical bradyarrhythmia; each had abnormal sinus node recovery time (greater than 1,400 ms) and abnormal corrected sinus node recovery time (greater than 525 ms) in at least one study. These seven patients also had a significantly prolonged ischemic time (236 +/- 26 versus 159 +/- 68 min, p less than 0.01). In conclusion, cardiac arrhythmias, particularly ventricular tachycardia and bradyarrhythmia, occur more commonly early after orthotopic heart transplantation than has previously been reported. Sinus node dysfunction due to prolonged organ ischemic time, antiarrhythmic drug use or surgical trauma, alone or in combination, may contribute to these arrhythmias.

[Chronic nonparoxysmal supraventricular tachycardia in children and adolescents]

An examination was performed in 111 children and adolescents with recurrent and sustained chronic nonparoxysmal tachycardias (CNPT). ECG and electrophysiological studies showed that ante- and retrograde conduction along the accessory atrioventricular junction was the most common mechanisms of arrhythmia. Holter monitoring revealed a high rigidity of cardiac rhythm in patients with sustained CNPT. Criteria for the development of arrhythmogenic cardiac dilatation were developed. In recurrent CNPT, there was a correlation between the paroxysms of ECG slow-wave activity and the "salvos" of tachycardia and a predominance of vagal effects on the heart. A new approach to the treatment of children with CNPT was proposed, which involved the correction of pathogenetic mechanisms. Indications for the usage of antiarrhythmic agents such as cordarone and a cardiac surgeon's advice were formulated. The efficiency of the therapy was achieved in 82% of the children as shown by a follow-up.

Atrial pacing: who do we pace and what do we expect? Experiences with 100 atrial pacemakers

The records of 100 patients with permanent atrial pacemakers implanted over a 7-year period were reviewed to assess the role and results of this mode of pacing. Indications for pacing were sick sinus syndrome in 91, carotid sinus hypersensitivity in 3, and use of an antitachycardia device in 6 patients. The mean follow-up period was 32.9 months. Symptomatic relief was good. Lead dislodgment occurred in 11 patients (usually in the first week). Threshold rises not amenable to reprogramming occurred in three patients and loss of sensing occurred in seven patients but only one required intervention. Overall, 21 patients required reoperation. The type of lead did not influence the need for reoperation that appeared to be related to the experience of the operator. Complete atrioventricular block occurred in three patients, two of whom had carotid sinus hypersensitivity and one had sick sinus syndrome. Chronic atrial fibrillation occurred in five patients, none of whom required revision of the pacemaker system. Atrial pacing is a satisfactory pacing mode in patients with sick sinus syndrome. Provided satisfactory atrioventricular conduction has been shown by incremental atrial pacing to at least 120 beats/min and carotid hypersensitivity is absent, progression to complete atrioventricular block is uncommon. Greater implanting skills are required for good results.

Frequency, characteristics and significance of supraventricular tachyarrhythmias detected by 24-hour electrocardiographic recording in the late hospital phase of acute myocardial infarction

The incidence, characteristics and clinical significance of supraventricular tachyarrhythmias occurring in the late hospital phase of acute myocardial infarction (AMI) were assessed in 209 consecutive patients. Arrhythmias were quantified by 24-hour electrocardiographic recording 16 +/- 3 days after AMI, and were classified according to the degree of complexity in 5 classes. Class 0 = less than 5 premature beats/hr; class 1 = between 5 and 100/hr; class 2 = greater than 100/hr or repetitive premature beats; class 3 = atrial-junctional tachycardia; class 4 = atrial flutter-fibrillation. Supraventricular tachyarrhythmias classes 1 to 2 always occurred in the absence of symptoms in 86 patients (41%); supraventricular tachyarrhythmias classes 3 to 4 (paroxysmal, self-limiting, brief) occurred in 27 patients (13%), symptomatically in 6. The presence of supraventricular tachyarrhythmias classes 2 to 3 was related to age over 55 years and complex ventricular tachyarrhythmias (greater than 20 premature beats/hr, ventricular tachycardia) (both p less than 0.05). Increasing complexity of supraventricular tachyarrhythmias was significantly associated with presence and entity of cardiac enlargement and left ventricular dysfunction (both p less than 0.01). Patients with class 4 showed the most severe cardiac deterioration. During the 2 years after AMI, patients with classes 2, 3 and 4 had a higher incidence of acute pulmonary edema, New York Heart Association functional classes III to IV for congestive heart failure (both p less than 0.005) and a greater need of digitalis and diuretics (p = 0.003).(ABSTRACT TRUNCATED AT 250 WORDS)

[Cardiac arrhythmias in childhood]

The knowledge of various dysrhythmias and their prognostic value permits the selection of appropriate diagnostic and management strategies. The most frequent pediatric dysrhythmias are described: premature atrial and ventricular contractions, supraventricular tachycardias, preexcitation syndrome, long Q-T syndrome, sick sinus syndrome, A-V blocks congenital and acquired. These arrhythmias may be related to structural abnormalities of the conduction system or may reflect temporary cardiac immaturity, as in the newborn, or may occur after surgical repair of a congenital cardiac lesion. It is important decide if the arrhythmias is benign and likely to resolve spontaneously or if it is potentially dangerous. Sometimes an arrhythmias indicates underlying extracardiac disease such as central nervous system disease, sepsis, hypoglycemia, drug toxicity, severe tissue hypoxia, electrolyte abnormalities. In these instances the treatment of the underlying cause will correct the rhythm abnormalities.