Pre and postoperative ventricular function in infants and children with right ventricular volume overload

Serum Levels of Natriuretic Peptides in Children before and after Treatment for an Atrial Septal Defect, a Patent Ductus Arteriosus, and a Coarctation of the Aorta-A Prospective Study

Background and Objectives. We evaluated and compared the influence of treatment for atrial septal defect (ASD), patent ductus arteriosus (PDA), and coarctation of the aorta (CoA) on serum levels of N-terminal proatriopeptide and N-terminal probrain natriuretic peptide. Correlations between peptide levels and echocardiographic measurements were calculated. Patients and Methods. Peptide levels were measured and echocardiography performed before and 6-12 months after treatment in 21 children with ASD, 25 with PDA, 15 with CoA, and 76 control children. Results. ANPN levels were higher than in controls at baseline in all patient groups, and NT-proBNP in patients with ASD and PDA. Both peptide levels were elevated 6 months after treatment and decreased thereafter. Peptide levels were higher in patients with volume than pressure overload. They correlated with echocardiographic measurements. At the 6-month follow-up, dimensions of the originally overloaded ventricle had normalized only in patients with PDA. Conclusions. After intervention, peptide levels decrease but normalization takes over 6 months. The type of correlation between peptide levels and echocardiography varies according to the loading condition. Measurement of peptide levels can be used for monitoring the course of a patient's heart disease.

Congenital diaphragmatic hernia and associated cardiovascular malformations: type, frequency, and impact on management

The co-occurrence of congenital diaphragmatic hernia (CDH) and cardiovascular malformations (CVMs) has important clinical, genetic, and developmental implications. Previous examinations of this topic often included patients with genetic syndromes. To correct this potential bias, we undertook an extensive review of the literature and obtained new data. The frequency of CVMs associated with isolated CDH was 11-15%. A careful analysis of CVMs indicates that atrial and ventricular septal defects, conotruncal defects, and left ventricular outflow tract obstructive defects were the most common type of CVMs, but proportional to the frequency of occurrence in the general population. The combination of CVM and CDH results in a poorer prognosis than would be expected with either malformation alone. However, the impact on survival from patients with a genetic syndrome has not been consistently evaluated. We encourage researchers to re-analyze existing series and recommend that future studies distinguish isolated CDH from that which is associated with other malformations, especially as part of genetic syndromes. Therapies should be tailored to maximize cardiac output and systemic oxygen delivery rather than systemic oxygen saturation alone. Although there is speculation about the frequency with which isolated left ventricular "hypoplasia" occurs in patients with CDH, we suggest it results from compression of a pre-load deficient left ventricle by the hypertensive right ventricle, and unlike true hypoplasia, is reversible. Irrespective of the type of severity of CVMs in patients with CDH, the degree of pulmonary hypoplasia and pulmonary vascular disease predicts outcome.

Conditions with right ventricular pressure and volume overload, and a small left ventricle: "hypoplastic" left ventricle or simply a squashed ventricle?

OBJECTIVES

We modeled the utility of preoperative potential left ventricular (LV) volume in predicting postoperative volume in conditions causing LV compression.

BACKGROUND

With right ventricular (RV) overload lesions, LV "hypoplasia" may be primarily due to compression by reverse septal bowing. If so, preoperative potential LV volume should correspond 1:1 with postoperative volume. The potential volume for a given endocardial circumference can be calculated from the maximal potential cross-sectional area (where A = circumference(2)/4pi) and LV length.

METHODS

We studied echocardiographic variables from 22 patients with RV overload lesions perioperatively.

RESULTS

Preoperative LV volume was 15.0 +/- 7.1 ml/m2 (59% of patients had a volume <15 ml/m2); potential volume was 20.0 +/- 9.8 ml/m2. Postoperative volume increased to 28.2 +/- 8.6 ml/m2 (100% of patients had a volume >15 ml/m2). Preoperative potential volume correlated well with, but generally underestimated, postoperative volume (r = 0.75, p < 0.0001). Postoperative increases in both LV circumference and length contributed to this discrepancy.

CONCLUSIONS

In RV overload lesions, LV "hypoplasia" is primarily due not to compression; rather it is due to underfilling. Even "hypoplastic" ventricles can achieve an adequate cavity after operation normalizes loading conditions. Both true and potential preoperative volume can predict postoperative volume well. However, potential volume, which is less prone to underestimating ventricular adequacy, may better help to determine suitability for biventricular repair in lesions of RV overload associated with a "hypoplastic" LV.

Is vertical vein ligation necessary in repair of total anomalous pulmonary venous connection?

BACKGROUND

In the repair of total anomalous venous connection, vertical vein ligation is recommended to eliminate left-to-right shunting. However, the small left heart chambers may not always tolerate the immediate increase in blood flow after combined repair and vein ligation.

METHODS

A retrospective review of 23 infants and children undergoing correction of total anomalous pulmonary venous connection was undertaken to determine whether vertical vein ligation is a necessary component of successful surgical repair. In 14 patients this vein was ligated, whereas in 9 it was left patent. Six patients who underwent ligation and 5 who did not had pulmonary venous obstruction before operation.

RESULTS

The operative mortality rate was 36% (5 of 14 patients) for the ligated group compared with 0% (0 of 9 patients) for the nonligated group (p = 0.06). All deaths occurred in patients with preoperative obstruction and a low mean left atrial pressure, and four of the deaths were directly attributable to left heart failure. Follow-up echocardiography in patients in whom the vertical vein was not ligated revealed adequate cardiac function and no residual left-to-right flow through the previously patent venous conduit.

CONCLUSION

Vertical vein ligation during the repair of total anomalous pulmonary venous connection is not routinely necessary and actually may be undesirable in patients with preoperative obstruction, in whom the left heart chambers are particularly small.

Myocardial recovery through ECMO after repair of total anomalous pulmonary venous connection: the importance of left heart unloading

A 7-day-old boy who had been placed on extracorporeal membrane oxygenation on his second day of life developed biventricular failure after undergoing surgical repair of a supracardiac variant of total anomalous pulmonary venous connection. Extracorporeal membrane oxygenation was again necessary for postoperative cardiopulmonary support. However, severe left ventricular failure made it imperative to leave the vertical vein open during support in order to decrease pressure on the left ventricle. The patient was successfully weaned from extracorporeal membrane oxygenation on day 8 after surgery and discharged from the hospital on day 23.

Cross-sectional echocardiographic measurement of right atrial and right ventricular size in children with atrial septal defect before and after surgery

A total of 25 children operated on for atrial septal defect were studied by cross-sectional echocardiography before and after operation. Right atrial and right ventricular dimensions and areas were measured preoperatively and 1-4 years (median, 32 months) postoperatively. The length, width, and area of the right atrium (RA) and the right ventricle (RV) were measured in the apical and the subcostal four-chamber views. The dimension of the RV outflow tract (RVOT) was measured in the parasternal short-axis view. Preoperatively, all group mean values except the subcostal four-chamber length of the RV were significantly larger than normal. After surgery, there was a significant decrease in all of the parameters studied, except for RV length. The mean postoperative values of RA measurements in the apical four-chamber view and of RVOT were still significantly larger than normal. The RV four-chamber measurements except the apical four-chamber length were not significantly enlarged. The greatest decrease in RA and RV size occurred in the first postoperative year. Longer follow-up periods did not change the measurements significantly.

Radionuclide measurement of right ventricular function in atrial septal defect, ventricular septal defect and complete transposition of the great arteries

Right ventricular (RV) function was assessed in 80 patients with congenital heart disease by first-pass and gated equilibrium radionuclide angiography. In 30 patients with a ventricular septal defect (VSD) the mean RV ejection fraction (+/- standard deviation) was 64 +/- 7%. In 30 patients with a secundum atrial septal defect it was 61 +/- 9% and in 20 patients with surgically corrected complete transposition of the great arteries it was 49 +/- 13%. These values are in close agreement with values established with cineangiography for similar groups of patients. The mean ejection fraction in the group with transposition of the great arteries was significantly less than in the group with VSD (p less than 0.001). Phase analysis of the equilibrium studies showed that there was delayed RV contraction in many patients in the absence of conduction abnormalities. This delay was significantly greater in patients with atrial septal defect than in those with VSD (p less than 0.05). There was a strong correlation between size of left-to-right shunt and phase delay in patients with VSD (r = -0.72). Thus, first-pass gated radionuclide angiography provides a valid measurement of RV ejection fraction, and delayed RV contraction on phase analysis may be a sensitive index of early RV dysfunction.

Evaluation of left ventricular function in chronical pressure load and the immediate changes after operative relief

Cardiac function and changes following surgery was studied with computerized M-mode echocardiography in 10 patients with left ventricular pressure load, mainly valvular aortic stenosis. Six of the patients were below 15 years of age. In the adults an unfavourable reduction of shortening fraction and VCF was encountered, whereas no such reaction was seen in the pediatric group. Both groups had a significant (p less than 0.005) drop in LV ejection time. In general, however, the study demonstrated a different reaction to surgery in children and adults, the peak rate of decrease of diameter (RDD) increased in children, and remained more or less unchanged in adults, and the normalized RDD acted similarly. The time for NRDD after QRS onset was reduced in all patients, but more obvious in children. The peak rate of increase of diameter (RID) was unchanged in both groups, but demonstrated an insignificant fall on the first postoperative day in adults. The study demonstrates different ways of reacting to surgery in pressure loaded adult and childhood left ventricles. We think these differences can be explained by less damaged myocardium in the pediatric age group.

The value of early repair for total anomalous pulmonary venous drainage

A total of 20 children with total anomalous pulmonary venous drainage (TAPVD) underwent complete repair within the past six years. The drainage was supracardiac in 11, infracardiac in seven, and into the coronary sinus in two. At repair mean age was nine weeks, and weight was 3.7 km. Operative technique in extracardiac types included complete mobilization of the common vein with division of anomalous channel when possible. The incision in the confluent vein was extended into the lobar veins when necessary to permit extensive incorporation of this structure into the posterior wall of the left atrium and resulted in a nonobstructing stellate-type anastomosis. Operative mortality was 10% (2 of 20). Deaths occurred only in the group of infants in whom severe obstruction to pulmonary venous return required emergency operation, and one of these patients has persistent neurologic deficit. Late cardiac catheterization has been performed in 11 of 18 survivors. Nine had no or only minor abnormalities and two required reoperation. There have been no late deaths with follow-up of 2-8 years (mean = 4 years). Currently, all of the survivors are without cardiac symptoms and only one requires cardiac medication. Our experience identifies pulmonary venous obstruction with critical symptoms as the major operative risk factor in patients with TAPVD. With early operation prior to onset of critical symptoms, mortality is low and functional results are excellent.

Right ventricular contractile function in children with congenital heart disease

Indexes of right ventricular (RV) systolic function were evaluated in 41 patients undergoing cardiac catheterization. High-fidelity tracings were used to determine RV pressure, maximal RV dP/dt and the velocity of contractile element shortening at a developed pressure of 10 mm Hg (VCE10). In 14 children with an RV systolic pressure less than 35 mm Hg, normal RV volume, pulmonary vascular resistance (PVR) less than 3 units X m2 and no shunts (our normal group), mean (+/- standard deviation) RV dP/dt was 437 +/- 116 mm Hg X s-1 and VCE10 was 1.15 +/- 0.33 muscle length X s-1. In patients with RV systolic hypertension due to valvular pulmonary stenosis or isolated increases in PVR, mean values for RV dP/dt and VCE10 were significantly (p less than 0.05) greater than the normal values. In patients with a ventricular septal defect, RV hypertension and normal PVR, VCE10 was normal but RV dP/dt was significantly elevated. Children with chronic RV volume overload had normal RV contractile indexes. No patient in any group had values for RV dP/dt or VCE10 that were less than normal (mean normal - 2 standard deviations). This study establishes for the first time the indexes of RV isovolumic systole in children. It also shows that RV contractile function is preserved in young patients with chronic RV pressure or volume overload who do not have overt congestive heart failure.

Long-term follow-up study after closure of secundum atrial septal defect in children: an echocardiographic study

Serial echocardiography was performed in 51 children with isolated secundum atrial septal defect before and after surgery to measure the effects of chronic right ventricular overload on ventricular function. Right ventricular dilation increased dramatically with growth and with size of the left to right shunt only in the youngest children (body surface area less than 0.5 m2). A lesser effect of growth and no significant effect of shunt size were noted in older children. Although an initial decrease in right ventricular size occurred in the first 3 months after operation, persistent right ventricular dilation remained up to 5 years after closure of the interatrial defect in more than 80 percent of patients. Preoperatively, the ratio of the right ventricular preejection period to ejection time was significantly less than that of normal children. This ratio increased dramatically after operation, exceeding normal values early in the postoperative period in 18 of 48 children and persisting in 6 of 22 after 3 months. Left ventricular dimensions were normal early and late after operation. Left ventricular function was apparently normal, although an exceptionally high shortening fraction was noted in 22 (44 percent) of 51 children after operation. Aortic systolic time interval ratios decreased after operation from high normal to low normal values. It is hypothesized that the persistent enlargement of the right ventricle after operation may be due to the chronic preoperative dilation secondary to chronic interatrial shunting. The abnormally high shortening fraction after operation may result from an abnormal left ventricular geometric configuration or abnormality of filling. It is suggested that surgical closure of the atrial defect in the first 3 years of life may prevent these abnormalities.