Prognostic significance of arrhythmia in tetralogy of Fallot after intracardiac repair

Postoperative ventricular tachycardia in patients with congenital heart disease: diagnosis and management

Ventricular tachycardia (VT) after palliative repair of congenital heart disease is relatively rare. Despite this rarity, VT is a known cause of early, intermediate and late morbidity and mortality in these patients. A number of factors have been linked to the development of VT in this unique patient population. The purpose of this article is to provide a concise overview regarding the etiology, diagnosis and treatment of VT in patients with congenital heart disease. In-depth information will be provided to aid diagnosis and the treatment of early postoperative VT. The use of additional diagnostic methods such as echocardiography, cardiac catheterization and electrophysiology studies to risk assess patients with postoperative VT will also be discussed. In addition, I examine the long-term management strategies for VT in these patients, from medical management and cardiovascular surgery to implantation of cardioverter-defibrillators.

Tetralogy of Fallot: Late outcome after repair and surgical implications

Cardiac surgery has transformed the outcome for patients with tetralogy of Fallot. Repair has conveyed excellent long-term results with most patients remaining well and leading normal lives. However, there are problems with late morbidity and mortality primarily due to right ventricular dysfunction, exercise intolerance, arrythmia, and sudden cardiac death. There has been a dynamic shift in our surgical approach to managing patients with tetralogy over the past 5 decades. This in part accounts for persisting difficulties in predicting late outcome for evry single patient with repaired tetralogy of Fallot. There are, however, several confounding variables, influencing long-term outcome for these patients, namely the underlying anatomical substrate, age at repair, surgical approach to repair, and residual hemodynamic abnormalities. It is gratifying to see that recent knowledge accumulated from long-term follow-up studies is influencing contemporary surgical practice. Individualized strategies aiming to minimize the potential for free pulmonary regurgitation, and the long-term detrimental effects associated with it, need to continue to develop. Preservation of right ventricular and pulmonary valve function combined with early restoration of normal pulmonary blood flow are likely to convey an even better long-term outlook for these patients. Further follow-up studies with assessment of bi-venticular function, however, are needed in both our older and contemporary cohorts with repaired tetralogy of Fallot. Copyright 2000 by W.B. Saunders Company

Arrhythmogenic substrate in young patients with repaired tetralogy of Fallot: role of an abnormal ventricular repolarization

Ventricular repolarization analysis has been shown to be effective in the identification of electrical myocardial instability leading to ventricular arrhythmias. The aim of the present study was to examine ventricular repolarization time indexes, in terms of both absolute measures and dispersion across the myocardium, in young patients with repaired tetralogy of Fallot (41 pts; 28M/13F, age 11.7+/-3.6 years), assessing, furthermore, the possible influence of known negative prognostic factors relative to the surgical operation and residual haemodynamic abnormalities. The data of the study group were compared with those of 33 aged-matched asymptomatic control subjects (22M/11F, age 11.7+/-2.3 years). Ventricular depolarisation, as expressed by QRS duration, resulted significantly longer in total Fallot group than in the Control group (P<0.0001). Particularly, patients operated through a right ventricular approach showed higher values of QRS interval (P<0.0001) than those operated through a combined transatrial-transpulmonary approach. All the patients operated on for tetralogy of Fallot exhibit, with respect to control subjects, an inhomogeneous prolongation of ventricular repolarization across the myocardium, as showed by the significant increase in the absolute indexes of ventricular repolarization, JTc (P<0.001), QT (P<0.0001) and QTc (P<0.0001) with a concomitant prolongation of the indexes of dispersion of ventricular recovery time, QTcD (P<0.0001), JTcD (P<0.0001), 'adjusted' QTcD (P<0.001) and Tp-Te interval (P<0.0001). A temporal and regional variation in the ventricular repolarization across the myocardium in patients with repaired tetralogy of Fallot, could create the pathophysiological substrate for an increased cardiac electrical instability. The presence of negative prognostic factors, relative to the surgical intervention or residual haemodynamic abnormalities, even if not influencing the arrhythmic substrate, invariably present, could determine 'trigger' conditions essential for the development of ventricular arrhythmias.

Significant intraoperative right ventricular outflow gradients after repair for tetralogy of Fallot: to revise or not to revise?

BACKGROUND

This study was performed to define alternative parameters for the management of intraoperative residual right ventricular outflow obstruction (RVOTO) after transatrial repair of tetralogy of Fallot (ToF) in order to differentiate those requiring immediate revision from those who do not.

METHODS

Since October 1995, 166 patients of ToF underwent transatrial repair. Postbypass residual RVOTO was assessed by surgeon's subjective impression, direct intracardiac pressure measurements, and intraoperative echocardiography (IOE). RVOTO was labeled "significant" whenever it exceeded a gradient of 40 mm Hg on IOE or right ventricular to left ventricular pressure ratio (pRV/LV) exceeded 0.85. Further, on IOE, significant RVOTO was defined "fixed", if there was no change in RVOT dimensions during the cardiac cycle, along with the presence of anatomic substrate for obstruction, and "dynamic" if RVOT dimensions increased appreciably in diastole. Postoperative course and follow-up echocardiograms of all patients were analyzed.

RESULTS

Significant RVOTO was detected in 58 (35%) patients (mean gradient 54 mm Hg). Seven (12%) of them with fixed obstruction (mean 46 mm Hg) underwent immediate surgical revision, while the remaining 51 patients with mean gradient of 78 mm Hg (including 10 patients with pRV/LV ratio of > or = 1.0) with dynamic obstruction did not undergo revision. There were six (3.6%) early deaths. Operative mortality and postoperative morbidity were not related to higher residual gradients, although the first 15 such patients had longer intensive care stay and inotropic support, in which this was done electively. On follow-up (mean 18.5 months), outflow gradients declined sharply (mean 16 mm Hg) irrespective of the severity of intraoperative gradients (p < 0.001). There were no reoperations or late deaths.

CONCLUSIONS

This study shows that: 1) existing parameters for immediate revision of residual RVOTO possibly need to be reviewed; 2) intraoperative echocardiography helps in differentiating "fixed" from "dynamic" obstruction and helps obviate needless revisions; and 3) dynamic RVOT gradients decline significantly irrespective of their severity after transatrial repair of ToF.

Reduced heart rate variability following repair of tetralogy of Fallot

OBJECTIVE

To examine autonomic function as assessed by heart rate variability in patients 10 or more years after repair of tetralogy of Fallot, and to relate this to cardiac structure, function, and electrocardiographic indices.

METHODS

Heart rate variability was measured by standard time domain techniques on a 24 hour Holter ECG in 28 patients, aged 12 to 34 years (mean 19.5), who had undergone repair of tetralogy of Fallot at least 10 years previously. Echocardiography was performed to assess left ventricular size and function, right ventricular size and pressure, and any proximal pulmonary arterial stenosis. Right ventricular function was evaluated by radionuclide scan. QRS duration, QT interval, and QT dispersion were measured on a standard 12 lead ECG. Measurements of heart rate variability were compared with values from 28 age matched healthy controls (mean age 19.9 years). Interrelations between variables were assessed using Pearson correlation coefficients and stepwise regression analysis.

RESULTS

Heart rate variability was reduced, compared with values for age matched normal controls, in 12 of the 28 patients. Reduced heart rate variability was associated with increased age, increased right ventricular size and pressure, and widening of the QRS complex.

CONCLUSIONS

Reduced heart rate variability is a feature following repair of tetralogy of Fallot. It is associated with increasing age, impaired right ventricular haemodynamics, and widening of the QRS complex. Under these circumstances, reduced heart rate variability may be a marker for deteriorating right ventricular function. Increased QRS duration has been identified as a risk factor for sudden death following repair of tetralogy of Fallot, and impaired cardiac autonomic control may be one of the mechanisms involved.

[Arrhythmias in patients with congenital heart disease and their impact on prognosis]

Patients with congenital heart disease have an increased chance to suffer from brady- as well as tachyarrhythmias. The impact of these on quality of life, morbidity and mortality is more often imperative as compared to heart-healthy individuals. The substrate for these may be either congenital or acquired. Improvements of the surgical management of these patients have led, on the one hand, to improved survival rates with prolonged life expectancy within the last 2 decades, which on the other hand provided the basis for a higher rate of acquired cardiac arrhythmias. Together, this not only challenges diagnostics and therapy but also the prognostic relevance of these arrhythmias. The therapeutic strategies and prognostic markers have until now mostly been based on retrospective studies limited by the low number of patients and inhomogeneous patient selection. Despite these limitations, an increased risk of sudden cardiac death has been substantiated for certain patient groups, e.g., those operated on by the Mustard- or Senning procedures in patients with transposition of the great arteries and patients operated on with correction of the tetralogy of Fallot. However, until now it has not been possible to identify reliable markers for establishing the risk on an individual basis within these patient cohorts. For achieving reliable data on the symptomatic and prognostic effects of present-day--as well as new-coming--therapeutic strategies, it is mandatory to perform prospectively based, randomized multicenter studies. Furthermore, the well-appreciated synergism of hemodynamically and primarily of arrhythmia-based effects on prognosis could potentially be divided into their relative weight to better guide appropriate, substrate-related therapy. In addition, this should help to get better estimates of the risk for sudden cardiac death in different, etiologically homogeneous, groups of patients with congenital heart disease.

Atrial arrhythmias in adults after repair of tetralogy of Fallot. Correlations with clinical, exercise, and echocardiographic findings

BACKGROUND

The long-term success of intracardiac repair of tetralogy of Fallot is hampered by the occurrence of arrhythmias. Numerous studies have stressed the potential role of ventricular arrhythmias. However, the importance of other arrhythmias in the morbidity of these patients appears to be underestimated. Furthermore, most follow-up studies have been limited to children or adolescents, whereas many patients have reached adulthood after earlier repair of tetralogy of Fallot. The aim of the present study was to determine the incidence of atrial fibrillation, atrial flutter, and other supraventricular arrhythmias in adult patients after intracardiac repair for tetralogy of Fallot and their correlation with surgical and clinical findings.

METHODS AND RESULTS

The study group consisted of 53 consecutive patients referred to the Thoraxcenter adult congenital heart disease clinic. They underwent repair at a mean age of 9.1 years (range, 0.7 to 55 years). The median age at the time of study was 23.2 years (range, 15 to 57 years; mean age, 26.6 years), and the mean duration of follow-up of 17.5 years (range, 1.4 to 32 years) after surgery. Records were reviewed extensively for evidence of arrhythmias. The follow-up study included routine 12-lead ECG, 24-hour continuous ambulatory monitoring, and echocardiography, and 46 patients underwent exercise testing. Sinus node dysfunction was recorded in 19 patients (36%), of whom 4 required a permanent pacemaker. Atrial fibrillation or flutter was found in 12 patients, and other supraventricular tachycardias were found in 6. The former were more frequently of older age at follow-up. Antiarrhythmic therapy and cardioversion were typically directed at control of atrial (and not ventricular) tachyarrhythmias. Ten patients (19%) showed nonsustained ventricular tachycardia; they were older at initial surgery and older at follow-up and had more intracardiac repairs and longer cardiopulmonary bypass times.

CONCLUSIONS

Despite an emphasis on ventricular ectopy in past series, the main sources of morbidity in adult patients after surgical correction of tetralogy of Fallot emanated from atrial arrhythmias, which were present in one third of the patients.

Role of late potentials in identifying patients at risk for ventricular tachycardia after surgical correction of congenital heart disease

This study evaluates the role of late potentials in identifying patients with sustained ventricular tachycardia (VT) after surgery for congenital heart defects using right ventriculotomy. Nine patients with early (1 to 12 months) or late VT (spontaneous in 7 [induced during electrophysiologic study in 6 of the 7] and induced in 2) and 104 patients without VT were studied. All patients had complete right bundle branch block. Late potentials were quantified by 3 time-domain parameters of the signal-averaged electrocardiogram: total filtered QRS duration, root-mean-square voltage in the last 40 ms, and low-amplitude signal duration of the terminal filtered QRS complex. Root-mean-square voltage filtered at 80 to 250 Hz was lower in patients with than without VT (9 +/- 6 vs 16 +/- 8 microV, p < 0.01). By multivariate analysis, more complex surgery (i.e., insertion of extracardiac conduits, Kawashima operation, etc.), lower root-mean-square voltage, and higher Lown grade (2 to 5) of ventricular arrhythmias on routine postoperative Holter recordings were the only independent predictors of VT (p < 0.001, < 0.05, and < 0.05, respectively). A combination of more complex surgery, root-mean-square voltage < 14 microV, and Lown grade 2 to 5 ventricular arrhythmias was highly predictive of VT (positive predictive value 75%). Conversely, patients without complex surgery and with root-mean-square voltage of > 13 microV were not likely to develop VT (negative predictive value 100%). Late potentials are an independent predictor of VT and may improve the identification of patients at low and high risk of VT after surgery for congenital heart defects using right ventriculotomy.

Prognostic significance of ventricular arrhythmia after repair of tetralogy of Fallot: a 12-year prospective study

OBJECTIVE

The aim of this study was to examine the prognostic significance of ventricular arrhythmia on the ambulatory electrocardiogram (ECG) after repair of tetralogy of Fallot.

BACKGROUND

Ventricular arrhythmia is common after repair of tetralogy of Fallot and has been proposed as the basis for late sudden death. The prognostic significance of ventricular arrhythmia on ambulatory ECG and the indications for therapy are uncertain.

METHODS

We performed a 48-h ambulatory ECG in 86 patients (3 to 45 years old [mean age 14 years]) after repair of tetralogy of Fallot. These patients were then followed up prospectively for 12 years.

RESULTS

At initial assessment in 1980, 47 patients (55%) had infrequent uniform ventricular extrasystoles (16 patients) or normal cardiac rhythm (31 patients) Group 1), and 39 patients (45%) had frequent uniform ventricular extrasystoles (> 30/h, 2 patients), complex extrasystole (30 patients) or nonsustained ventricular tachycardia (7 patients) (Group 2). There were no significant clinical or hemodynamic differences between the groups. In addition, nine patients had supraventricular tachyarrhythmia. Antiarrhythmic therapy was prescribed only for the 10 patients who had symptoms attributable to arrhythmia. There were two sudden deaths in Group 1 (4%) and one nonsudden death in Group 2 (2.5%). The absolute difference in mortality between groups was therefore 1.5% (95% confidence limits -6% to +9%), excluding a clinically significant difference in outcome. All but 1 of the 39 patients with complex ventricular arrhythmia are alive and well, including those with elevated (> or = 60 mm Hg) right ventricular pressure.

CONCLUSIONS

Nonsustained ventricular arrhythmia on ambulatory ECG does not identify patients at high risk for sudden death after repair of tetralogy of Fallot. There does not appear to be any advantage in potentially dangerous long-term antiarrhythmic therapy for asymptomatic postoperative patients.

Late ventricular arrhythmia is rare after early repair of tetralogy of Fallot

OBJECTIVES

This study was conducted to describe the incidence of ventricular arrhythmia during prospective long-term follow-up in a group of patients who had repair of tetralogy of Fallot during early childhood.

BACKGROUND

Ventricular arrhythmia has been a common finding in patients who have undergone repair of tetralogy of Fallot in late childhood or as adults. Whether earlier repair lowers the incidence of late ventricular arrhythmia or late sudden death is unknown.

METHODS

Twenty-nine asymptomatic patients who underwent repair at age 1.2 to 7.7 years (mean [+/- SD] age 4 +/- 1.4 years) between 1979 and 1984 were studied. Twenty-one patients had simple repair (Group A), and eight had complex or multiple operations (Group B). All had ambulatory electrocardiographic monitoring preoperatively, postoperatively, at early follow-up (after 4.2 +/- 1.3 years) and again at late follow-up (after 11.8 +/- 1.3 years). At late follow-up, 28 subjects also underwent echocardiography, and 26 had an exercise test.

RESULTS

No patient had significant ventricular arrhythmia (> or = modified Lown grade 2) before or immediately after repair. There was no significant increase in the incidence of arrhythmia at early and late follow-up (14% to 28%), but at each of these periods the incidence of ventricular arrhythmia was higher in Group B patients (3 [43%] of 7 vs. 1 [5%] of 22 with early repair, p = 0.03; 6 [75%] of 8 vs. 2 [10%] of 21 with late repair, p = 0.001). No patient had symptoms of arrhythmia, and there were no sudden deaths. Late ventricular arrhythmia did not correlate with estimated right ventricular systolic pressure, outflow tract gradient or degree of pulmonary incompetence or right ventricular dilation. On exercise, 5 (19%) of 26 patients had ventricular premature complexes at low levels of exercise that were suppressed at maximal exercise in all patients.

CONCLUSIONS

Late ventricular arrhythmia is rare in patients with successful early correction of tetralogy of Fallot, unless complex or multiple operations are performed.

Rapid ventricular pacing in dogs with right ventricular outflow tract obstruction: insights into a mechanism of sudden death in postoperative tetralogy of Fallot

OBJECTIVES

We explored the hypothesis that residual outflow tract obstruction and ventricular hypertrophy associated with rapid ventricular rhythm contribute to sudden death, in part because they result in humoral or hemodynamic changes that predispose to ventricular fibrillation, such as increased catecholamine release or decreased coronary flow, or both.

BACKGROUND

Ventricular arrhythmia after surgical repair of tetralogy of Fallot has been associated with sudden death, particularly in patients with residual right ventricular hypertension. However, the mechanisms by which sudden death occurs remain unclear.

METHODS

Seven awake, unanesthetized mature beagles with chronically elevated right ventricular pressure (high pressure group: right ventricular/left ventricular systolic pressure ratio > 0.5) were compared with six beagles with low right ventricular pressure at rest and at the end of 5 min of ventricular pacing at 240 beats/min (low pressure group).

RESULTS

In the high pressure group, cardiac output decreased during ventricular pacing (compared with sinus rhythm) from 304 +/- 21 to 218 +/- 21 ml/min per kg (p < 0.01) and plasma norepinephrine increased substantially from 673 +/- 64 to 1,047 +/- 92 pg/ml (p < 0.01). Comparable changes were not observed in the low pressure group. Plasma epinephrine levels were similar in both groups at rest and did not change with pacing. Postpacing norepinephrine levels from both groups correlated positively with both right ventricular systolic and diastolic pressure at rest and correlated negatively with the change in cardiac output from rest to pacing. Regional right ventricular myocardial blood flow increased with pacing in the low pressure group, whereas in the high pressure group it was increased at rest and did not increase further with pacing.

CONCLUSION

During ventricular pacing, dogs with right ventricular outflow tract obstruction and high right ventricular pressure had a decrease in cardiac output and an increase in plasma norepinephrine, coupled with a loss of right ventricular myocardial blood flow reserve. Similar changes may occur in postoperative patients with similar hemodynamics and tachyarrhythmia and could contribute to the occurrence of ventricular fibrillation and sudden death.

Frequency and prognosis of arrhythmias after operative "correction" of tetralogy of Fallot

Two hundred twenty-four consecutive patients operated on for tetralogy of Fallot were followed from 1 to 28 years (mean 11). Mean age at surgery was 5.3 years (range 1 to 14). Postoperative right ventricular systolic pressure was 60 mm Hg in 19 of 213 patients (9%). Fourteen patients (6%) had ventricular premature complexes on surface electrocardiograms. Seventy-nine patients underwent treadmill exercise tests, and ventricular premature complexes were induced in 17 (22%). Twenty-four-hour ambulatory monitoring in 92 patients demonstrated significant ventricular arrhythmias (greater than or equal to grade 2 of the Lown classification) in 41 (45%). The frequency of ventricular arrhythmias correlated with length of follow-up and duration of cardiopulmonary bypass. No correlation was found with age at surgery, postoperative right ventricular systolic pressure and importance of conduction defects on electrocardiogram. There were no sudden or unexpected deaths during follow-up.

Ventricular arrhythmias in postoperative tetralogy of Fallot

Ventricular arrhythmias in patients after total surgical repair of tetralogy of Fallot have been associated with late sudden death. In this large multicenter retrospective study of 359 patients with postoperative tetralogy of Fallot, spontaneous ventricular premature complexes (VPCs) on 24-hour ambulatory electrocardiographic monitoring and laboratory-induced ventricular tachycardia (VT) by electrophysiologic stimulation were analyzed. The mean age at surgical repair was 5 years and the mean follow-up duration after repair was 7 years. Spontaneous VPCs on ambulatory monitoring were found in 48% and induced VT on electrophysiologic stimulation was found in 17% of patients. Both spontaneous VPCs and induced VT were significantly related to delayed age at repair, longer follow-up interval, symptoms of syncope or presyncope and right ventricular systolic hypertension (greater than 60 mm Hg) (p less than 0.05), but not to right ventricular diastolic pressure greater than 8 mm Hg. The VPCs on ambulatory monitoring were more complex with increasing age at repair and follow-up duration. Induction of VT on electrophysiologic stimulation correlated with spontaneous VPCs including VT on 24-hour ambulatory electrocardiographic monitoring. The electrophysiologic stimulation protocol varied and the induction of VT increased with a more aggressive stimulation protocol. While induced sustained monomorphic VT was related to all forms of spontaneous VPCs, induced nonsustained polymorphic VT was related to more complex forms of VPCs on ambulatory monitoring. VT was not induced in asymptomatic patients who had normal 24-hour ambulatory electrocardiographic monitoring and normal right ventricular systolic pressure. (ABSTRACT TRUNCATED AT 250 WORDS)

Exercise-induced ventricular arrhythmia after repair of tetralogy of Fallot

Treadmill exercise electrocardiography (TE) was recorded in 50 patients to evaluate the incidence of exercise-induced ventricular arrhythmias (VAs) in a group of patients who underwent corrective surgery of tetralogy of Fallot (TF) more than four years previously. The results of rhythm evaluation were correlated with cardiac catheterization data as well as clinical information such as the age at surgery and the interval from surgery. Of the 50 patients tested, ventricular premature contraction (VPC) was confirmed in 12 patients (24%) on TE, while five patients (10%) demonstrated VPC on the standard ECG. The interval from surgery was significantly longer in those patients with VA (Group 1) than those without VA (Group II) on TE (p less than 0.05). There was no significant difference of the age at corrective surgery between the two groups. In group I, the preoperative hemoglobin level was higher (p less than 0.05) and the right ventricular ejection fraction was lower (p less than 0.01). Exercise-induced VAs are closely related to the length of period after surgery and the depressed right ventricular function.

Late results in patients with tetralogy of Fallot repaired during infancy

Between 1973 and 1985, 220 infants (age 1 day to 18 months, mean = 7 months) underwent repair of tetralogy of Fallot (TOF) or TOF/pulmonary atresia with 17 early deaths. Follow-up status was ascertained for 184 of 203 survivors (91%) at a postoperative interval of 2 to 185 months (mean = 60 months). Significant residual hemodynamic lesions included ventricular septal defect in three, and right ventricular outflow gradient in excess of 40 mm Hg in 24. Reoperation or interventional catheter procedures were performed in 31 of 184 (17%) patients. All postoperative electrocardiograms were reviewed; only two of 184 patients had ventricular ectopy on any tracing. Holter data from 41 patients revealed one with sinus node dysfunction, 12 with Lown grade 1 ectopy, and one with Lown grade 2 or greater. Conduction defects, evaluated by electrocardiographic and electrophysiologic measurements, were not different from those reported for TOF patients undergoing repair at later ages. No study patient received antiarrhythmic medication, although one required a pacemaker for sinus node dysfunction. There were three late deaths, all unrelated to arrhythmia. TOF repair in infancy appears to be associated with an acceptable hemodynamic outcome, and a low incidence of ventricular ectopy and sudden death at 5 year follow-up.

Electrophysiologic drug testing in symptomatic ventricular arrhythmias after repair of tetralogy of Fallot

Nine patients with symptomatic ventricular arrhythmias were evaluated a mean interval of 16 years after surgical repair of tetralogy of Fallot. The clinical arrhythmia was sustained ventricular tachycardia (VT) in 4 patients (group I) and premature ventricular contractions in 5 (group II). All patients underwent cardiac catheterization and electrophysiologic studies. Ventricular tachycardia was induced at electrophysiologic study in all patients in group I and in 3 patients in group II. Six patients with inducible sustained monomorphic VT underwent chronic drug testing based on electrophysiologic study. A mean of 3.3 drugs per patient was tested. Patients with right ventricular systolic hypertension did not respond to any drug tested, and underwent surgery. Five patients received drug treatment based on the results of electrophysiologic study. During a mean follow-up period of 2.2 years, no patient in either group had recurrent episodes of VT or syncope. In the postoperative patient with tetralogy of Fallot with symptomatic ventricular arrhythmias, it is concluded that electrophysiologic study is useful in reproducing clinical episodes of VT and in selecting effective antiarrhythmic medication; a small number of patients with ventricular premature complexes alone will have inducible sustained VT during electrophysiologic study; prognosis of these patients may be improved by treatment that results in prevention of VT induction; and in patients with right ventricular hypertension, VT is likely to be refractory to drug treatment.

EEG monitoring during paroxysmal hyperpnea of tetralogy of Fallot: an epileptic or hypoxic phenomenon?

We describe a neurologically compromised infant with tetralogy of Fallot who was having multiple paroxysmal episodes of hypotonia, eye rolling, stiffening, and loss of consciousness. Simultaneous electroencephalography with video monitoring was used to determine if these episodes were a primary epileptic phenomenon or the result of hypoxic central nervous system involvement from paroxysms of hyperpnea and cyanosis. The findings would suggest that the paroxysmal episodes were not primarily epileptic. The electroencephalographic findings during the spell were similar to those found with hypoxia due to other causes. This may have physiological and therapeutic significance and be useful in following other infants with congenital heart disease who have similar episodes, especially when the infants have significant risk factors for seizures.

Frequency of ventricular late potentials and fractionated right ventricular electrograms after operative repair of tetralogy of Fallot

This study was conducted to assess the incidence of abnormalities of ventricular depolarization in sinus rhythm after repair of tetralogy of Fallot and their relation to spontaneous ventricular arrhythmias. Forty-four patients were studied, 10 before surgery (mean age 6.9 years) and 34 after repair (mean age 8.1 years, mean age at surgery 6.5 years, mean interval between surgery and evaluation 11 months). Evaluation was performed by means of body surface and intracavitary signal-averaging techniques, by recording local right ventricular (RV) electrograms at several sites and by 24-hour Holter monitoring (n = 28). No electrophysiologic abnormality was observed in children before surgery. Ventricular late potentials were detected in 18 patients (53%) after repair. Body surface detection of ventricular late potentials was frequently masked by the postoperative right bundle branch block pattern. Local RV electrograms were fractionated in 11 cases (32%) (mean duration 103 +/- 33 ms), most often in the RV outflow tract (n = 9), but no relation was found between fragmentation of RV electrograms and the presence of ventricular late potentials. Spontaneous ventricular arrhythmias occurred in 12 children after repair (43%), but were complex in only 4 patients (14%). There was no correlation between spontaneous ventricular arrhythmias and the presence of ventricular late potentials, presence of fractionated RV electrograms, presence of a proximal right bundle branch block or postoperative hemodynamic status.(ABSTRACT TRUNCATED AT 250 WORDS)

Ambulatory electrocardiographic study of the frequency and cause of ventricular arrhythmia after correction of tetralogy of Fallot

Ambulatory 24-hour electrocardiographic monitoring with a Holter recording system was performed in 100 patients after repair of tetralogy of Fallot. The incidence and severity of ventricular arrhythmia (VA) were studied relative to operative age, follow-up period after corrective surgery, hemodynamic data, ventricular function and operative method. Significant VA (Lown grade 2 to 4) was detected in 41 patients. Patients with significant VA (group I) were older (11.7 +/- 10.0 years old) at operation than those without VA (group II) (5.5 +/- 5.8 years, p less than 0.001). The follow-up period after operation in group I (9.5 +/- 4.8 years) was significantly (p less than 0.001) longer than that in group II (5.5 +/- 4.3 years). The incidence of elevated right ventricular (RV) systolic pressure was significantly (p less than 0.005) higher in group I (43%) than in group II (7%). RV ejection fraction in group I (48 +/- 6%) was significantly (p less than 0.001) lower than that in group II (56 +/- 5%). The new operative method for tetralogy of Fallot without or with minimal right ventriculotomy was more frequently performed in group II (49%) than in group I (15%, p less than 0.005). Pulmonary regurgitation, RV and left ventricular size, and left ventricular ejection fraction were not related to severity of VA. Thus, serious VA was related to higher age at operation, longer interval after surgery, elevated RV systolic pressure, depressed RV ejection fraction and RV scar.

Analysis of adults with and without complex ventricular arrhythmias after repair of tetralogy of Fallot

Forty-four adult patients with tetralogy of Fallot were studied while clinically well at a mean of 14 years (range 5 to 27) after intracardiac repair to examine the association of postoperative ventricular arrhythmias with historical and postoperative hemodynamic data. Twenty-two patients who demonstrated during 24 hour ambulatory monitoring or maximal graded treadmill exercise testing, or both, ventricular premature beats that were multiform, repetitive or increased in frequency during exercise or recovery after exercise were found to differ from patients without such ventricular premature beats in four respects. The patients with complex or exercise-induced ventricular premature beats had a higher right ventricular systolic blood pressure, a higher incidence of residual left to right intracardiac shunt, lower cardiac index and more frequently abnormal left ventricular ejection fraction measured by rest and exercise-gated radionuclide ventriculography. Adults with complex or exercise-induced ventricular premature beats after intracardiac repair of tetralogy of Fallot are characterized by suboptimal hemodynamic repair and preclinical left ventricular dysfunction.

Life threatening ventricular tachycardias in late survivors of surgically corrected tetralogy of Fallot

Electrophysiological tests were performed in three patients with surgically corrected tetralogy of Fallot (mean age at evaluation 25 years, mean age at surgical correction 4 years) who had had either a cardiac arrest or transient neurological disturbances (presyncope, syncope) associated with ventricular arrhythmias. All three patients had an excellent haemodynamic result from surgery as judged by echocardiography and cardiac catheterisation. Ambulatory electrocardiographic monitoring and stress exercise testing were normal in two patients and showed complex ventricular ectopy in one. During invasive electrophysiological evaluation all three patients had inducible ventricular tachycardia (monomorphic QRS in two patients, cycle lengths 230 and 240 ms; polymorphic QRS in one patient, mean cycle length 200 ms) with adverse haemodynamic effects in all three patients. These findings suggest that rapid ventricular tachycardia with detrimental haemodynamic consequences, similar to that induced during laboratory study, was the basis for the presenting symptoms in each patient. This possibility was confirmed in one patient who had identical QRS morphology during both spontaneous ventricular tachycardia and that induced during the laboratory study. Thus sudden death or symptoms of syncope postoperatively in patients with surgically corrected tetralogy of Fallot appear to be due to rapid ventricular tachycardia, which may occur despite an apparently excellent surgical result.

Sustained ventricular tachycardia after repair of tetralogy of Fallot: new electrophysiologic findings

Ventricular arrhythmia originating from the outflow tract of the right ventricle is a presumed cause of late sudden death in patients after repair of tetralogy of Fallot. Exercise testing has been shown to enhance detection, and phenytoin has been shown to control ventricular arrhythmias in these patients. This study reports new findings in 3 patients who underwent electrophysiologic studies at postoperative cardiac catheterization; in each, sustained ventricular tachycardia was induced and found to originate from the inflow-septal area of the right ventricle. Using serial studies, the same sustained ventricular tachycardia was induced during therapeutic serum concentrations of phenytoin but not after propranolol. No patient had ventricular arrhythmia during a 24-hour electrocardiogram or during exercise. Although no patient had normal hemodynamic function, only 1 patient had right ventricular pressure greater than two-thirds systemic pressure. Each patient had undergone initial intracardiac repair at a relatively late age (3, 9, and 9 years).

Hemodynamics and intracardiac conduction after operative repair of tetralogy of Fallot

Electrophysiologic studies were performed in 47 children aged 3 to 18 years, 15 of whom had cardiac arrhythmias 1 to 15 years after repair of tetralogy of Fallot. Six exhibited sinus or atrioventricular nodal dysfunction, 8 had ventricular extrasystoles, and 1 had supraventricular tachycardia. Hemodynamic and electrophysiologic data were obtained at postoperative catheterization. Although electrophysiologic responses were abnormal in a proportion of both the children with and those without arrhythmia, hemodynamic values were similar. Three of 6 children with impaired sinus impulse generation or atrioventricular nodal conduction had a prolonged A-H interval, and in 3 Wenckebach heart block developed at low pacing rates. Ventricular ectopic rhythm was not associated with any particular abnormality of basic intracardiac conduction intervals. Thus, arrhythmias and conduction abnormalities are not consistently related to residual right ventricular hypertension. Abnormalities in electrophysiologic function are common after repair of tetralogy of Fallot in patients with sinus rhythm and may have prognostic implications for these patients.

Hemodynamic abnormalities in response to supine exercise in patients after operative correction of tetrad of Fallot after early childhood

The exercise hemodynamic values in two groups of patients with repaired tetrad of Fallot (eight patients with some residual pulmonary insufficiency and seven patients without insufficiency) were compared with values in seven patients with trivial pulmonary stenosis who had not been operated on. The patients with tetrad of Fallot underwent surgery after age 8 years and all had a good hemodynamic repair (no shunts and a right ventricular systolic pressure at rest of less than 60 mm Hg). Exercise increased the right ventricular outflow tract gradient by the same magnitude in all three groups of patients. However, both surgically treated groups experienced impaired cardiac pump function on supine exercise (that is, a lower than anticipated cardiac index for the amount of oxygen consumed and a significant decrease in stroke index). Exercise also caused both groups with repair to have a decrease in stroke index and a concomitant increase in right ventricular end-diastolic and pulmonary wedge pressures; in contrast, the patients with pulmonary arterial stenosis had an increase in stroke index and a concomitant decrease in right ventricular end-diastolic and pulmonary wedge pressures. These findings indicate that an impaired cardiac response to supine exercise can occur in patients in whom intracardiac repair of tetrad of Fallot was performed after early childhood, even though they have had a good hemodynamic repair. In addition, the impaired cardiac response to supine exercise in these patients was probably due largely to an altered myocardial compliance rather than to either residual pulmonary stenosis or pulmonary insufficiency.