Prevention of sudden death after repair of tetralogy of Fallot: treatment of ventricular arrhythmias

The majority of sudden deaths after repair of tetralogy of Fallot have been presumed to be due to ventricular arrhythmia; however, it remains to be demonstrated that antiarrhythmic medication reduces the incidence of sudden death. Since 1978, ventricular arrhythmias have been treated aggressively; these include any ventricular arrhythmia on routine electrocardiogram and more than 10 uniform premature ventricular complexes per hour on 24 hour electrocardiogram. A review was undertaken of 488 patients followed up for more than 1 month after repair of tetralogy of Fallot (mean follow-up time 6.1 years); 13.5% had ventricular arrhythmia on routine electrocardiogram. Ventricular arrhythmia appeared from 2 months to 21 years postoperatively (mean 7.3 years). Ventricular arrhythmias were significantly (p less than 0.01) related to: longer follow-up duration, older age at follow-up, older age at operation and higher postoperative right ventricular systolic and end-diastolic pressures. Ventricular arrhythmia on routine electrocardiogram occurred in 100% of those who later died suddenly compared with 12% of those who did not die (p less than 0.01). Treatment for ventricular arrhythmia was given to 46 patients and considered "successful" if there were fewer than 10 uniform premature ventricular complexes per hour on 24 hour electrocardiogram. A successful drug was found in 44 of the 46: 30 of 34 given phenytoin, 6 of 9 given propranolol, 1 of 7 given quinidine, 1 of 2 given disopyramide, 8 of 9 given mexiletine and 4 of 5 given amiodarone.(ABSTRACT TRUNCATED AT 250 WORDS)     

Quantitative radionuclide angiocardiography: Detection and quantitation of left to right shunts

In 105 patients detection and quantitation of left to right shunts was performed using quantitative radionuclide angiocardiography. The radionuclide angiocardiograms were acquired and analyzed by a gamma camera interfaced to a digital computer system. Pulmonary to systemic flow ($\text{Qp}\text{Qs}$) ratios were calculated by analysis of pulmonary time-activity histograms using a gamma variate model. All patients were studied with cardiac catheterization, left ventricular angiocardiography and radionuclide angiocardiography. The radionuclide method allowed precise detection and quantitation of left to right shunts with a $\text{Qp}\text{Qs}$ ratio of 1.2 to 3.0. There was good agreement between the $\text{Qp}\text{Qs}$ ratio calculated by oximetry at cardiac catheterization and radionuclide angiocardiography (r = 0.94). The information gathered with this nontraumatic method appears sufficiently reliable to be used in the management of patients.     

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.     

Incidence and factors favouring ventricular arrhythmia after surgical repair of tetralogy of Fallot

The prevalence and factors favorising postoperative ventricular arrhythmias in 62 patients undergoing surgical repair of tetralogy of Fallot between 1971 and 1982 were analysed. Nineteen patients (31 %) had significant ventricular arrhythmias (Lown greater than or equal to 2) on Holter monitoring or exercise stress testing. The arrhythmia could only be recorded after stress testing in 5 patients. The patient's age at operation, the duration of follow-up and age at evaluation were significantly greater in the group with ventricular arrhythmias. However, age at operation was closely related to the other two parameters and a discriminating analysis showed that the age at operation was not a favorising factor for the occurrence of ventricular arrhythmias (p = 0.23), in contrast to the duration of follow-up (p = 0.0015) and age at evaluation (p = 0.0007). No relationship was found between ventricular arrhythmias and the following factors: previous anastomosis, outflow patch, necessity of a ventriculotomy or reoperation, presence of residual ventricular septal defect, postoperative systolic right ventricular pressure, severity of intraventricular conduction defects, and effort tolerance. These results suggest that after surgical repair of tetralogy of Fallot, the incidence of ventricular arrhythmias increases with time. The main problem is to identify patients with a high risk of sudden death, i.e. those with high degree ventricular arrhythmias and poor haemodynamic results of repair.     

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 (≥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.     

Lung function and pulmonary regurgitation limit exercise capacity in postoperative tetralogy of Fallot

Fifty-five patients with repair of tetralogy of Fallot were evaluated with treadmill exercise, pulmonary function testing and rest two-dimensional and Doppler echocardiography to determine the relation among cardiopulmonary function, exercise capacity and ventricular arrhythmias. The mean age at repair was 8.1 +/- 2.1 years; age at the time of study ranged from 15 to 37 years (mean follow-up time after repair 18 +/- 5 years). Exercise duration was 92 +/- 17% of predicted. Maximal heart rate was 94 +/- 7% of predicted. No exercise test was stopped because of an arrhythmia. Thirty patients had oxygen consumption and ventilation measured during their final minute of exercise. Peak oxygen consumption was 31 +/- 8 ml/kg per min (86 +/- 18% of predicted). Twenty-five patients (45%) had low vital capacity at rest (less than 80% of predicted). Pulmonary regurgitation was identified in 42 (75%) of the patients and judged to be moderate in 10 (18%). Mild tricuspid valve regurgitation was identified in 64%. Doppler estimated right ventricular outflow gradient was greater than 15 mm Hg in 15% of the patients (mean gradient 24 mm Hg [range 16 to 56]). Age at repair, duration of follow-up and type of repair did not correlate with echocardiographic variables, ventilatory data, exercise performance or arrhythmias. Moderate pulmonary regurgitation was associated with increased right ventricular diastolic area and both were inversely related to exercise duration and vital capacity. Decreased breathing reserve during maximal exercise was associated with moderate pulmonary regurgitation and decreased vital capacity. The results indicate that exercise capacity in these patients is in general good; however, right ventricular volume loading and ventilatory dysfunction may produce exercise limitation.     

Tachycardias of right ventricular origin.

Ventricular tachycardia arising from the right ventricle usually has a left bundle branch morphology and occurs in a variety of disorders. Uhl's anomaly and right ventricular dysplasia may represent a spectrum of one disorder and are a cause of right heart dilatation, failure, and premature sudden death due to ventricular arrhythmias. Familial forms of the disorder may account for focal clustering in some geographic areas. Management should involve aggressive stratification of arrhythmia risk and may include medical, surgical, or device therapy. In contrast, the syndrome of right ventricular outflow tract tachycardia, including nonischemic exercise-induced and repetitive monomorphic ventricular tachycardia, is a more benign entity. Management often involves beta- and calcium channel blocking drugs or type IC antiarrhythmic drugs. Catheter ablation of the arrhythmia focus in the right ventricular outflow tract has been used in selected patients. In this syndrome the right ventricle is normal, and noninvasive testing as well as electrophysiologic studies can be helpful in distinguishing it from the more malignant right ventricular dysplasia. Ventricular arrhythmias may also be seen after right ventricular incision, as in surgical repair of tetralogy of Fallot and ventricular septal defects. Significant ventricular ectopy associated with an abnormal right ventricle (enlarged or depressed systolic function) is associated with an increased risk for sustained arrhythmia and sudden cardiac death in this group. The optimal indicator(s) of highest risk in these patients remains under investigation but will likely include electrophysiologic testing. Bifascicular block occurs commonly after repair of tetralogy of Fallot, but is usually benign. Isolated right ventricular infarction is rare. Most right ventricular arrhythmias associated with ischemia occur in the setting of iatrogenic catheter manipulation for pacing or hemodynamic monitoring. In conclusion, right ventricular arrhythmias involve an unusual and interesting group of clinical entities and appear to span the spectrum of arrhythmias mechanisms. A macroreentrant activation ring around the ventriculotomy scar may account for the arrhythmias following repair of tetralogy of Fallot. Microreentry at sites of morphologic abnormalities results in the arrhythmias associated with right ventricular dysplasia and ischemia. Triggered activity related to DADs or, less likely, abnormal automaticity, produce repetitive monomorphic ventricular tachycardia and nonischemic exercise-induced ventricular tachycardia, both of which usually originate from the right ventricular outflow tract. Iatrogenic ventricular tachycardia associated with catheter manipulation is especially likely to occur in the presence of right ventricular ischemia and infarction. It is important to recognize these clinical entities because treatment is specific.(ABSTRACT TRUNCATED AT 400 WORDS)     

Postoperative haemodynamics in tetralogy of Fallot. A study of 132 children.

Our study was undertaken to determine the type, incidence, and functional significance of residual anomalies in patients who have undergone corrective repair for tetralogy of Fallot. We reviewed data from cardiac catheterisations performed on 132 survivors. A significant residual ventricular septal defect was present in only 12 patients. Resting right ventricular systolic pressure was less than 80 mmHg in 100 patients and ranged from 80 to 150 mmHg in the other 32 patients. Thirty-five patients were studied both at rest and during supine exercise. In most patients, the relation between oxygen consumption and cardiac output was normal during exercise. The stroke index and right ventricular end-diastolic pressure at rest and on exercise were compared in 34 patients. Seventeen showed a normal response to exercise. In the other 17 patients, right ventricular end-diastolic pressure rose on exercise; in 5 of these the stroke index fell during exercise, indicating abnormal myocardial response. Our studies indicate the frequent occurrence of residual abnormalities, even in patients who appear asymptomatic, after total correction of tetralogy of Fallot.     

Postoperative haemodynamics in tetralogy of Fallot. A study of 132 children.

Our study was undertaken to determine the type, incidence, and functional significance of residual anomalies in patients who have undergone corrective repair for tetralogy of Fallot. We reviewed data from cardiac catheterisations performed on 132 survivors. A significant residual ventricular septal defect was present in only 12 patients. Resting right ventricular systolic pressure was less than 80 mmHg in 100 patients and ranged from 80 to 150 mmHg in the other 32 patients. Thirty-five patients were studied both at rest and during supine exercise. In most patients, the relation between oxygen consumption and cardiac output was normal during exercise. The stroke index and right ventricular end-diastolic pressure at rest and on exercise were compared in 34 patients. Seventeen showed a normal response to exercise. In the other 17 patients, right ventricular end-diastolic pressure rose on exercise; in 5 of these the stroke index fell during exercise, indicating abnormal myocardial response. Our studies indicate the frequent occurrence of residual abnormalities, even in patients who appear asymptomatic, after total correction of tetralogy of Fallot.     

Cardiorespiratory response to exercise after repair of tetralogy of Fallot

We studied 24 patients who had a graded exercise test 1 to 16 years after correction of tetralogy of Fallot. Maximal oxygen consumption was subnormal in 19 of the patients. We found no relationship between age at repair, postoperative right ventricular pressure, right ventricular-to-pulmonary artery pressure gradient, or ratio of right ventricular and left ventricular pressure and degree of exercise intolerance. The stroke volume response to exercise was normal in only three of eight patients. Twenty-five percent of patients had arrhythmia just prior to, during, or after exercise. The arrhythmias were independent of the factors of age at repair, age at exercise, previous operation, presence of an outflow tract patch, or residual right ventricular outflow tract obstruction. The ventilatory responses to exercise were normal. Persistent exercise intolerance may be due, in part, to abnormal ventricular function.     

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.     

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).     

Ventricular arrhythmia and tetralogy of Fallot repair with transannular patch.

OBJECTIVE: Life-threatening arrhythmias and sudden death remain to be serious late complications after correction of tetralogy of Fallot. The aim of this study was to detect ventricular arrhythmia incidence and to find out the relationship between ventricular arrhythmia and the transannular and infundibular patch repair techniques to correct tetralogy of Fallot. That is still unpredictable exactly. METHODS: Thirty-nine patients with mean age of 12.1+/-3.1 years were studied prospectively for 7.1+/-2.1 years after operation. They were all investigated with electrocardiography, echocardiography, treadmill and Holter monitorization. Right ventricular functions, exercise capacity and arrhythmia patterns were assessed. Lown criteria were used for grading the arrhythmia patterns. QRS duration, QT dispersion and QT dispersion indexes were calculated. RESULTS: Follow up time was 5 to 13 years in both groups. All QT dispersion times and indexes were within normal ranges and there were no differences between two groups. Holter and treadmill studies did not reveal during any ventricular arrhythmia risk in the study and control groups. CONCLUSION: Seven years of follow-up after correction of tetralogy of Fallot revealed that transannular patch reconstruction is not a cause of tendency for ventricular arrhythmia according to Lown criteria, QT dispersion, QT dispersion indexes and QRS duration do support the results of previous studies.     

Ventricular premature contraction after repair of tetralogy of Fallot--the influence of postoperative factors, particularly the right ventricular regional wall motion

The presence and severity of ventricular premature contraction (VPC) in 35 patients with tetralogy of Fallot (TF) were studied, 5 to 10 years after intracardiac repair (ICR), using treadmill exercise testing and 24-hour ambulatory monitoring. VPCs were observed in 24 patients (68.6%). The patients were classified into two groups according to the types of VPCs: group A (23 patients) without VPCs or with VPCs of Lown's grade 1 and group B (12 patients) with VPCs of Lown's grade 2, 3 or 4. Group B patients were found to have significantly higher right to left ventricular peak-systolic pressure ratios and higher right ventricular peak systolic pressures than those of group A. But there were no significant differences between the two groups in operative age, the time lapse between ICR and evaluation, the duration of exercise and so on. Group B patients also showed significantly decreased right ventricular regional wall motions in the right ventricular outflow tracts (ROTs), indicating akinetic or paradoxical movements than group A patients. It is thought that postoperative right ventricular hypertension and the akinetic or paradoxical wall movement of the ROT may have some effect on the genesis of postoperative VPCs after repair of TF.     

Unexpected cardiac arrest in patients after surgical correction of tetralogy of Fallot.

Four of 220 patients without bifasicular block (complete right bundle branch block and left anterior hemiblock) or transient complete heart block immediately after surgery had an unexpected cardiac arrest one to 15 years after satisfactory surgical repair of tetralogy of Fallot. The postoperative electrocardiograms (ECG) revealed complete right bundle branch block in two patients and no intraventricle conduction abnormality in two patients. Each of the four patients had premature ventricular contractions on previous postoperative ECG. The cardiac arrest occurred during normal activity in three patients and mild exercise in one. Following the cardiac arrest, three patients died and one patient survived. Eighteen months before the cardiac arrest, the survivor had a stress test which revealed multifocal premature ventricular contractions with short bursts of ventricular tachycardia after exercise. This ventricular arrhythmia was suppressed with quinidine therapy. Although complete heart block cannot be excluded in these four patients, we reasoned that the cardiac arrests were probably preceded by ventricular tachyarrhythmia. Because of this experience, we believe that any patient who has had intraventricular surgery should be evaluated for ventricular arrhythmia. If frequent premature ventricular contractions or serious ventricular arrhythmias are documented, we seriously consider antiarrhythmic therapy in an attempt to prevent ventricular tachyarrhythmias and sudden death.     

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)     

Ventricular arrhythmias and biventricular dysfunction after repair of tetralogy of Fallot

To test the hypothesis that subclinical levels of ventricular dysfunction contribute to the development of ventricular arrhythmias after repair of tetralogy of Fallot, 38 postoperative patients were studied by radionuclide ventriculography and M-mode echocardiography. Eighteen patients (group I) had Lown grade 2 or greater ventricular arrhythmias on ambulatory electrocardiography or treadmill exercise, or both; 20 patients (group II) had no documented ventricular arrhythmias. Radionuclide ventriculograms were performed using technetium -99m-labeled red cells; ejection fractions were derived by computer from multigated images, with normal values being 45% for the right ventricle and 55% for the left ventricle. From M-mode echocardiography, right and left ventricular end-diastolic dimensions were expressed as a ratio, the highest normal value being 0.45. By radionuclide ventriculography, right ventricular ejection fraction was lower for group I (28 +/- 3%) than for group II (31 +/- 2%), but the difference was not significant (p less than 0.10). Left ventricular ejection fraction was significantly lower for group I than for group II (45 +/- 5% versus 55 +/- 3%, p less than 0.05). The echocardiographic right and left ventricular diastolic dimension ratio was elevated in all patients except two in group II; it was significantly greater in group I than in group II (0.84 +/- 0.06 versus 0.63 +/- 0.04, p less than 0.005). This study provides evidence for right ventricular dilation by M-mode echocardiography and for biventricular dysfunction by radionuclide ventriculography in patients who have undergone repair of tetralogy of Fallot.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prognostic significance of arrhythmia in tetralogy of fallot after intracardiac repair

The significance of arrhythmia and conduction defects was studied in 395 patients who underwent intracardiac repair of tetralogy of Fallot between 1958 and 1976. In 91 of these patients (group I), the median date of repair was 1964 and all underwent stress testing. In 107 patients (group II), the median date of repair was significantly later (1971), but all subjects were too young for stress testing. The remaining 197 patients (group III, median date of repair 1963) included all those who did not participate in stress testing or who had died; 42 of these patients were later excluded from analysis because of insufficient electrocardiographic records. The overall incidence of any form of arrhythmia (19 percent) was the same for each group. However, in group II (patients who underwent intracardiac repair more recently), no tachyarrhythmia was observed and there were fewer patients with 1° atrioventricular (A-V) block (p <0.001) and more patients with complete right bundle branch block (p <0.001) than in groups I and III. In two patients (both in group I), unexpected, late sudden death unrelated to strenuous physical activity occurred. Arrhythmia was least common in patients with primary intracardiac repair and more common in those with either palliation before intracardiac repair or multiple intracardiac repairs. In group I, 41 of 91 patients with arrhythmia of even minor degree at rest (n = 13) or exercise (n = 28) had a significantly larger heart, greater right ventricular pressure and lesser exercise performance than did those without arrhythmia, thus suggesting the presence of residual abnormality or dysfunction. No tachyarrhythmia was induced by exercise in this study. Patients with either arrhythmia or bifascicular block have generally had a benign course without strong evidence of progression of arrhythmia.     

Left ventricular dimensions and function during exercise in dogs with chronic right ventricular pressure overload

Left ventricular (LV) dimensions and shortening at rest and during treadmill exercise were examined before and after 4 weeks of pulmonary artery (PA) constriction in 6 conscious dogs. The dogs were preinstrumented with LV and right ventricular (RV) catheters, an LV micromanometer, a PA inflatable cuff occluder and ultrasonic crystals to measure an LV anteroposterior, a septal-lateral, an apex-base and a free wall segment chord. With PA constriction, RV pressures increased from $\text{49 ±}\text{4}\text{2}\text{± 1 mm}$ Hg (systolic/end-diastolic) to $\text{104 ±}\text{5}\text{2}\text{± 1}$ at rest and from $\text{71 ±}\text{9}\text{2}\text{± 1}\text{to}\text{133 ±}\text{8}\text{14}\text{± 2}$ at peak exercise (mean ± standard error of the mean). Heart rate, LV pressure and LV dP/dt were similar before and after RV pressure overload at rest and with exercise. During exercise at control, systolic shortening increased significantly in all chords. With chronic PA constriction at rest, shortening of all chords also remained normal despite decreases in end-diastolic dimensions, which were most marked in the septal-lateral chord (23% decrease, p <0.01). However, during exercise in the presence of RV pressure overload, septal-lateral shortening decreased 46% (p <0.01) despite increases in systolic shortening in the other chords similar to the control response. Therefore, although LV function at rest in chronic RV pressure overload is normal, exercise may induce regional abnormalities of LV contraction that appear to be mediated by a reduced contribution of the ventricular septum to LV ejection.     

Prognostic significance of ventricular arrhythmia after repair of tetralogy of fallot: A 12-year prospective study

Objectives. 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 (3 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 nossudden 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 (≥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.