Pacing threshold spikes months and years after implant.

To determine patterns of variation in chronic pacing thresholds, we made 4,942 threshold measurements in 257 patients with 312 leads, at times from implant to 295 months (median 17 months) including 1,053 determinations in 46 children less than 12 years old. Motivation was late sudden death in two single-ventricle pacemaker-dependent children with multiple possible death causes. At stimulus duration 0.5 +/- 0.04 msec, mean of the thresholds, measured 1 month or more after implant, was 1.3 +/- 0.66 volts (V) for endocardial electrodes and 2.8 +/- 1.39 V for epicardially applied electrodes. Highest mean thresholds were in the 6 to 12-year-old age group. In 34 leads studied at implant, again within a month and for at least three years thereafter, time of maximum threshold occurred after one month in 59%, independent of lead type or patient age. Of 107 leads with five or more measurements after 3 months use, gradual increase in threshold continued after 3 months in 24%. An additional 21% had at least one threshold that exceeded the post-three-months individual patient lead mean by three standard deviations. Most striking was the occurrence of transient several-volt increases and decreases in threshold as late as 8 years after lead implantation in at least three children. These temporary changes were detected initially transtelephonically by the vario method of threshold measurement. They occurred during minor illnesses such as summer colds, yet similar illnesses also occurred without threshold elevation. We suggest further study of pacing threshold variations in highly pacemaker-dependent children whose cardiac anatomy makes use of epicardial electrodes necessary.

Complete transposition of the great arteries: treatment in the current era.

Transposition of the great arteries usually can be diagnosed by fetal echocardiography, which is important because the arterial switch operation, currently the treatment of choice, must be performed very early in life. The results of the arterial switch operation have been good to date. The dilemma remains, however, whether a fetus in whom a diagnosis of transposition is made should be aborted or treated surgically soon after delivery.

Corrective repair of complete atrioventricular canal defects and major associated cardiac anomalies.

Twenty-nine patients with balanced forms of complete atrioventricular (AV) canal defects and tetralogy of Fallot in 12, double-outlet right ventricle (DORV) in 10, and additional anomalies associated with atrial isomerism in 7 underwent corrective repair. Age ranged from 39 days to 24 years (median, 3.7 years). Repair included reconstruction of the common AV valve in 25 patients and prosthetic valve replacement in 4. Construction of an intraventricular tunnel connecting the left ventricle with the aorta was accomplished in 23 of 25 patients with ventriculoarterial concordant or double-outlet connections. In 2 patients with situs inversus and associated DORV and in 4 patients in the isomerism group who had ventriculoarterial discordant connections, repair included intraatrial venous diversion by a modified Senning procedure in 2, a modified Mustard venous switch in 1, and a tailored atrial baffle in 3. A valved extracardiac conduit was required for repair in 4 patients. Partial anomalous systemic venous connection was repaired in 7 patients and total anomalous pulmonary venous connection, in 5. There was 1 hospital death (3%) and 3 late deaths (11%). There was 1 (3.6%) reoperation to replace an incompetent right (systemic) AV valve 17 months postoperatively, and each of the 25 surviving patients was in New York Heart Association Functional Class I (80%) or II (20%) at follow-up.

Prediction of severe obstruction to right ventricular outflow after repair of tetralogy of Fallot and pulmonary atresia.

Cineangiograms were available for a quantitative retrospective study along with complete clinical information in 96 patients who underwent intracardiac repair of tetralogy of Fallot with pulmonary atresia. Multivariate analysis determined that the risk factors for too high a ratio (greater than or equal to 1) between the peak pressure in the right ventricle and that in the left, in the operating room about 30 minutes after repair, were as follows: size of the patient, small size of the right and left pulmonary arteries, and a larger number of large aortopulmonary collateral arteries. When, according to the multivariate equation, the predicted probability of this ratio being equal to or greater than 1 is 50% or more, consideration may be given to preliminary operations before repair; when the predicted probability is 70% or more, complete repair at that stage may be unwise.

Survival, functional status, and reoperations after repair of tetralogy of Fallot with pulmonary atresia.

DATA: Among 139 patients who underwent repair of tetralogy with pulmonary atresia, survival rates at 1 month and at 1, 5, 10, and 20 years were 85%, 82%, 76%, 69%, and 58%, respectively. The hazard function (instantaneous risk of dying) was greatest immediately after operation and declined thereafter, but a low constant hazard persisted for as long as the patients were followed up. Multivariately, the postrepair ratio between peak right ventricular and left ventricular pressures measured in the operating room provided the most information relative to the probability of death after repair, and cardiopulmonary bypass time the next. When morphologic abnormalities of the pulmonary circulation were considered in the multivariate analysis for risk factors for death, the size of the pulmonary arteries provided the most information, followed by the number of large aortopulmonary collateral arteries. The postrepair peak right ventricular/left ventricular pressure ratio was lower the day after operation than in the operating room in 65% of the patients in whom the measurements were made. Recurrent or residual ventricular septal defects necessitating rerepair occurred in four patients (3% of hospital survivors). Most surviving patients were in New York Heart Association class I at the time of follow-up. INFERENCES: Early, intermediate, and long-term survival is less good after repair of tetralogy with pulmonary atresia than after repair of tetralogy with pulmonary stenosis. This is related primarily to the greater prevalence of high peak right ventricular/left ventricular pressure ratio measured in the operating room in the former group. Both the postrepair peak right ventricular/left ventricular pressure ratio in the operating room and the probability of death are inversely related to the size of the pulmonary arteries and directly to the number of large aortopulmonary collateral arteries. This and inferences from other risk factors may be helpful in achieving better results in the future.

The structure of the pulmonary circulation in tetralogy of Fallot with pulmonary atresia. A quantitative cineangiographic study.

UNLABELLED: Cineangiograms of 172 patients with tetralogy of Fallot and pulmonary atresia were qualitatively and quantitatively analyzed retrospectively. FINDINGS: Twenty-eight (16%) patients had congenital absence of the central and unbranched hilar portions of the left or right pulmonary artery or both, and thus had congenitally nonconfluent pulmonary arteries. Five additional patients (3%) with originally confluent pulmonary arteries had nonconfluent ones because of an end-to-end surgical shunt, as did seven others (4%) because of thrombosis of one pulmonary artery. Among the 132 patients with confluent right and left pulmonary arteries, 70 (53% of 132) had incomplete arborization (distribution) of one or both, as did 23 (82% of 28) of those with congenitally nonconfluent pulmonary arteries (P for difference = 0.005). Ten (36% of 28) of the latter group had fewer than 10 pulmonary vascular segments (normal is 20) in continuity with central pulmonary arteries, compared with four (3%) of the former group. The proximal left and right pulmonary arteries were small but variable in size in all groups (median value 1.05 McGoon ratio), but were largest in the patients with confluent pulmonary arteries. Seventy-nine (60% of 132) patients with confluent left and right pulmonary arteries had large aortopulmonary collateral arteries, as did 100% of those with congenitally nonconfluent pulmonary arteries (P less than 0.001). The number of large aortopulmonary collateral arteries correlated inversely with the completeness of arborization of the left and right pulmonary arteries (P less than 0.0001). Inferences: Most patients with tetralogy and pulmonary atresia have gross morphologic abnormalities in the pulmonary vasculature and differ quantitatively in this regard from those with tetralogy and pulmonary stenosis. The prevalences of the various types of these abnormalities are considerably interrelated.

Subaortic stenosis and sudden death.

An obese white boy, 16 years old, collapsed and suddenly died while walking with friends. Since early childhood he had been known to have mild subaortic stenosis. At age 6 he exhibited first-degree heart block during an electrocardiographic exercise test. Neither then nor thereafter was he known to have any unusual symptoms until his death. Postmortem examination revealed marked cardiac enlargement without asymmetry or much dilatation. There was mild subaortic stenosis, but the heart was otherwise grossly normal. Special studies of his cardiac conduction system demonstrated fibrotic obliteration of the His bundle and proximal portions of both bundle branches. The same region had a much thickened central fibrous body from which the subaortic stenosis ridge protruded. Small arteries in the vicinity of the atrioventricular node were markedly narrowed. Because those vessels provide some of the blood supply to the His bundle region, their narrowing may have contributed to the fibrotic abnormalities observed. The extent of destruction of the His bundle makes a lethal failure of atrioventricular conduction the most likely terminal event.

Transatrial-transpulmonary repair of tetralogy of Fallot.

Classical tetralogy of Fallot was repaired by a transatrial-transpulmonary approach in 61 of 70 patients treated surgically on one surgical service between July 1981 and December 1985. Their ages ranged from 2.5 months to 57 years (mean 52.9 +/- 104.2 months). The ventricular septal defect was closed through the right atrium and tricuspid valve in 60 patients and via the pulmonary artery in one patient with a subpulmonary defect. A pulmonary arteriotomy was made in 38 patients to expose the stenotic pulmonary valve for valvotomy and to begin the infundibular mobilization and resection. It was extended through a small pulmonary anulus primarily in 15 patients and secondarily in one, a minimal distance upon the right ventricular infundibulum to enlarge the outflow tract to 2 standard deviations larger than the mean normal pulmonary valve anulus diameter. There were no hospital or late deaths or reoperations among the entire group. The mean postrepair peak right ventricular/left ventricular pressure measured in the operating room was 0.52 +/- 0.165 for the entire group of 61 patients which indicates similar relief of pulmonary stenosis to that obtained by the classical transventricular repair. At follow-up between 2.3 and 53.8 months (mean 22.6) each patient was in New York Heart Association Class I and without cardiac medication. Postoperative cardiac catheterization studies performed in nine patients between 4 and 28 months after operation showed no residual ventricular septal defects and a mean peak right/left ventricular pressure of 0.42 +/- 0.13. This series indicates that successful repair of tetralogy of Fallot can be accomplished in most patients by a transatrial-transpulmonary approach, which may provide improved right ventricular function over the long term.

Pericardial cyst diagnosed by two-dimensional echocardiography and computed tomography in a newborn.

A one-day-old full-term female infant with massive "cardiomegaly" developed marked respiratory distress soon after birth. The two-dimensional (2D) echocardiogram demonstrated a 4 X 5-cm cystic mass adjacent to the left ventricular free wall. Computed tomography (CT) confirmed the presence and dimension of the cyst and CT number indicated the fluid within the cyst to be serous. A pericardial cyst was successfully removed at thoracotomy. Two-dimensional echocardiography and CT, both noninvasive procedures, are fully adequate tools in the diagnosis of pericardial cysts in the neonate, so that invasive investigations may be avoided.

The Fontan operation. Ventricular hypertrophy, age, and date of operation as risk factors.

One hundred two patients, aged 0.7 to 38 years, with a wide variety of cardiac malformations underwent the Fontan operation (1975 to April, 1985). Several different techniques were used. All but 17 had previously undergone one or more palliative operations. Follow-up information was obtained in all patients. Overall actuarial survival rate, with time zero being the time of the operation, was 63% at 6 years with no deaths after that in patients followed as long as out to 9.4 years; that for patients with tricuspid atresia was 81%. The hazard function (instantaneous risk) for death was highest immediately after operation and merged after about 6 months with a constant hazard extending as long as the patients were followed. Elevated post-repair right atrial pressure was correlated (p = 0.002) with the probability of death in the early phase, with the risk rising rapidly with pressures above 14 mm Hg. Hypertrophy of the ventricular main chamber was a risk factor for death in both the early (p = 0.007) and late (p = 0.008) phases of hazard, which explained in part the lesser risk of the Fontan operation in patients with tricuspid atresia. Younger age, but not older age, was a risk factor for early postoperative death, but this risk was neutralized by recent date of operation. Thus currently there is not a predicted increased risk associated with younger age at operation. In general, the Fontan operation should be done at a young age (2 to 4 years) to avoid increasing ventricular hypertrophy, but older age per se is not a contraindication to the operation.

The repair of atrioventricular septal defects in infancy.

Two (3%) of 72 patients undergoing repair of atrioventricular septal defects, 1984-September 1985, died in hospital, and among the 58 patients with isolated atrioventricular septal defect, one (2%) died in hospital. One (3%) of the 30 patients with isolated atrioventricular septal defects undergoing repair in the first year of life died. The absence of an incremental risk of young age is a continuation of the trend demonstrated in a parametric analysis of the earlier 1967-1982 experience (n = 310). The hospital mortalities were similar in 1984-September 1985 after repair of partial and complete atrioventricular septal defects, again a continuation of the earlier trend as is the lessened hospital mortality (7%) in the current era among patients with major associated cardiac anomalies. The continuity of results in the two eras, and the predictability of the results in the current era from equations developed from the earlier one, give a high degree of confidence in the inference that primary repair in the first year of life is advisable for most patients with atrioventricular septal defects. Ten-year survival of such patients operated upon currently is predicted to be 99 and 95% for partial and complete atrioventricular septal defects, respectively.

Current risks and protocols for operations for double-outlet right ventricle. Derivation from an 18 year experience.

Recent follow-up of 127 patients having repair of double-outlet right ventricle during an 18 year experience (1967 to July, 1984) indicated an overall actuarial survival rate at 12 years of 38%. However, multivariate analysis supported by contingency tables indicated that currently the early (2 week) survival rate after the intraventricular tunnel repair for double-outlet right ventricle with subaortic ventricular septal defect in 6-month-old infants is 99% and the 10 year survival rate 97%. Reoperation of the tunnel repair was rarely required (one of 56 patients), and the functional results were excellent. Results were similar in patients with doubly committed ventricular septal defect, except that two of 10 patients developed typical discrete localized subaortic stenosis late postoperatively. Early and late results in patients with double-outlet right ventricle and subpulmonary ventricular septal defect were poor when an atrial switch operation was part of the repair; when an intraventricular tunnel repair between the left ventricle and aorta was combined with a right ventricular-pulmonary arterial conduit, no early deaths occurred, but three patients died late postoperatively. Several techniques of repair of double-outlet right ventricle with noncommitted ventricular septal defect have provided only a 22% overall 10 year survival rate. These data are used to derive inferences as to optimal treatment protocols.

Intraventricular tunnel repair for Taussig-Bing heart and related cardiac anomalies.

Uncertainty currently exists as to the optimal definitive procedure for treatment of patients with the Taussig-Bing heart and related cardiac anomalies. Between December 1, 1981 and October 1, 1985, we have used a completely intraventricular tunnel repair, without the use of an extracardiac conduit, in nine patients between 1 and 33 months of age. There was one hospital death from low cardiac output in a 1-month-old infant and one late death 11 months after repair from preexisting and progressive right ventricular cardiomyopathy. Six patients had the Taussig-Bing heart and three had transposition of the great arteries with a ventricular septal defect (VSD). The specific type of tunnel used was determined by the intracardiac anatomy and VSD enlargement was necessary in six patients. Three reoperations were required, two for recurrent VSD between 1 and 3 months after repair and one for tricuspid valve replacement in the patient with right ventricular cardiomyopathy 6 months later. The remaining seven patients are in NYHA class I 1.3 to 47 months postoperatively. We conclude that continued and perhaps expanded use of this technique is appropriate.

Spectrum of hearts with one underdeveloped and one dominant ventricle.

Hearts with one underdeveloped and one dominant ventricle form a spectrum of anomalies extending from the heart with two clearly adequate chambers to those with a true single ventricle. An angiographic concept of grouping such hearts is presented. 129 patients with unequal ventricles underwent catheterization and cineangiography between 1974 and 1983. The age at first catheterization ranged from one day to 24 years (mean 3.9 years). Male-female ratio was 2:1. Five groups of hearts (with their relative frequencies in the spectrum) were established: dominant left ventricle (53%); dominant right ventricle (20%), each with normally related chambers; dominant left ventricle (20%); dominant right ventricle (3%), each with ventricular inversion; true single ventricle (5%). The incidence of atrial anatomy, venous return, intracardiac connections and associated lesions within each group was assessed. From the standpoint of deranged physiology as well as surgical implications there are more similarities than differences among these hearts. The fact that one ventricle will not generate an adequate stroke volume after repair is overwhelmingly more important than most other considerations. For the diagnostic and surgical approach, we believe that the system offers many advantages.

Overriding atrioventricular valves. An angiographic-anatomical correlate.

An analysis of 6 patients with overriding atrioventricular valve was performed in order to correlate the anatomic and angiographic features of this malformation. The atrial arrangement was usual (situs solitus) in each patient. The ventricular chambers were normally related in 4 and the mirror image of normal in 2. The atrioventricular connexion was concordant in parallel fashion in 4, discordant in 1 and double inlet left ventricle in 1 heart. In 2 of 4 hearts with concordant atrioventricular connexion, the right atrioventricular valve (tricuspid) overrode the septum and connected partially to the left ventricle. In 2, the left atrioventricular valve (mitral) overrode the septum and partially connected with the right ventricle. One heart with discordant atrioventricular connexion had its right atrioventricular valve (mitral) overriding the septum. The remaining heart with double inlet left ventricle had an overriding left atrioventricular valve. Each overriding atrioventricular valve had its "septal" leaflet (the one committed to the contralateral ventricle) divided into 2 segments by a large cleft. Ventricular septal defects at different locations were present in all cases. The ventriculoarterial connexion was double outlet right ventricle in 5 patients and was discordant in 1. Malalignment of the atrial and ventricular septa was present to some degree in all cases. This was well depicted on ventriculograms in four chamber view in those with an overriding tricuspid valve. It was not detected in those with an overriding mitral valve. The displaced leaflets of the overriding and/or stradding valve had a vertical motion on cineangiograms similar to those observed in atrioventricular septal defects. Abnormal morphology and motion of the septal leaflet of the overriding atrioventricular valve and malalignment of the atrial and ventricular septal structures were the most important angiographic findings in this series.

Death and other events after cardiac repair in discordant atrioventricular connection.

The 1 month, 1 year, and 10 year actuarial survival rates after operation among 99 consecutive patients with discordant atrioventricular connection who underwent intracardiac repair are 86%, 75%, and 68%, respectively. The hazard function of death declines rapidly after operation to reach a low level 6 months postoperatively, and it becomes indistinguishable from that of a matched general population by 4 years. Risk factors for premature death include double-outlet right ventricle, complete heart block preoperatively or developing perioperatively, very young or older (greater than 25 years) age, a high hematocrit value, and earlier date of operation. The last indicates improvement in results in recent years. Eleven (11%) of 99 patients had complete heart block preoperatively, and 23 (26% of 88) developed it perioperatively. Patients with discordant ventriculoarterial connection (i.e., corrected transposition) had a lesser probability of developing heart block after repair than did those with other ventriculoarterial connections. Seventeen (17%) patients required tricuspid (pulmonary venous) valve replacement or repair at the original intracardiac operation, and eight additional patients developed important incompetence after repair. Among the risk factors for incompetence was an Ebstein-like anomaly of the tricuspid valve. Reoperations (three) for conduit obstruction have been no more common than in patients with concordant atrioventricular connection. Fifty-seven (81%) of 70 surviving patients are in New York Heart Association Class I and 12 (17%) in Class II. This, and the single-phase hazard function, indicate that the overall results of cardiac repair in patients with atrioventricular discordant connection could become excellent if the early risks were overcome.