Longitudinal study of ventricular function after the Mustard operation for transposition of the great arteries: a long term follow up

Pathogenesis and Surgical Treatment of Dextro-Transposition of the Great Arteries (D-TGA): Part II

Dextro-transposition of the great arteries (D-TGA) is the second most common cyanotic heart disease, accounting for 5-7% of all congenital heart defects (CHDs). It is characterized by ventriculoarterial (VA) connection discordance, atrioventricular (AV) concordance, and a parallel relationship with D-TGA. As a result, the pulmonary and systemic circulations are separated [the morphological right ventricle (RV) is connected to the aorta and the morphological left ventricle (LV) is connected to the pulmonary artery]. This anomaly is included in the group of developmental disorders of embryonic heart conotruncal irregularities, and their pathogenesis is multifactorial. The anomaly's development is influenced by genetic, epigenetic, and environmental factors. It can occur either as an isolated anomaly, or in association with other cardiac defects. The typical concomitant cardiac anomalies that may occur in patients with D-TGA include ventriculoseptal defects, patent ductus arteriosus, left ventricular outflow tract obstruction (LVOTO), mitral and tricuspid valve abnormalities, and coronary artery variations. Correction of the defect during infancy is the preferred treatment for D-TGA. Balloon atrial septostomy (BAS) is necessary prior to the operation. The recommended surgical correction methods include arterial switch operation (ASO) and atrial switch operation (AtrSR), as well as the Rastelli and Nikaidoh procedures. The most common postoperative complications include coronary artery stenosis, neoaortic root dilation, neoaortic insufficiency and neopulmonic stenosis, right ventricular (RV) outflow tract obstruction (RVOTO), left ventricular (LV) dysfunction, arrhythmias, and heart failure. Early diagnosis and treatment of D-TGA is paramount to the prognosis of the patient. Improved surgical techniques have made it possible for patients with D-TGA to survive into adulthood.

Limited Ventricular Preload is the Main Reason for Reduced Stress Reserve After Atrial Baffle Repair

The atrial baffle repair (ABR) significantly improved the fate of patients with transposition of the great arteries (TGA). However, these patients show impaired exercise tolerance and some present severe decline of systemic ventricular function. Intrinsic myocardial weakness, low heart rate response to exercise and diastolic filling impairment are discussed to be causative. Forty-nine long-term survivors with TGA (median age 23.7 year) after ABR were catheterized with measured oxygen consumption in four conditions (baseline, volume, atrial pacing, dobutamine) and the results were compared to 10 normal controls. Median cardiac output was significantly lower in the ABR group (2.2 vs. 2.6 l/min/m²; p = 0.015), and systemic resistance was significantly elevated (28.9 vs. 22.2 U m²; p = 0.04) in comparison with normals. While stroke volume rose by 27% in the control group, it dropped by 7% in patients after ABR at atrial pacing (80/min). Stroke volume increase after dobutamine was significantly lower after ABR in comparison with normal controls (34 vs. 106%; p = 0.001). Higher NYHA class (p = 0.043), degree of tricuspid regurgitation (p = 0.009) and ventricular function (p = 0.028) were associated with lower stroke volume increase. Limited exercise capability of patients after ABR for TGA is primarily due to limited diastolic filling of the ventricles due to stiff non-compliant atrial pathways. Elevated systemic resistance may lead to severe myocardial hypertrophy with possible ischemia and contribute to the multifactorial decline of ventricular function in some patients.

Total isovolumic time relates to exercise capacity in patients with transposition of the great arteries late after atrial switch procedures

BACKGROUND

Systemic right ventricular systolic dysfunction is common late after atrial switch surgery for transposition of the great arteries. Total isovolumic time is the time that the ventricle is neither ejecting nor filling and is calculated without relying on geometric assumptions. We assessed resting total isovolumic time in this population and its relationship to exercise capacity.

METHODS

A total of 40 adult patients with transposition of the great arteries after atrial switch - and 10 healthy controls - underwent transthoracic echocardiography and cardiopulmonary exercise testing from January, 2006 to January, 2009. Resting total isovolumic time was measured in seconds per minute: 60 minus total ejection time plus total filling time.

RESULTS

The mean age was 31.6 plus or minus 7.6 years, and 38.0% were men. There were 16 patients (40%) who had more than or equal to moderate systolic dysfunction of the right ventricle. Intra- and inter-observer agreement was good for total isovolumic time, which was significantly prolonged in patients compared with controls (12.0 plus or minus 3.9 seconds per minute versus 6.0 plus or minus 1.8 seconds per minute, p-value less than 0.001) and correlated significantly with peak oxygen consumption (r equals minus 0.63, p-value less than 0.001). The correlation strengthened (r equals minus 0.73, p-value less than 0.001) after excluding seven patients with exercise-induced cyanosis. No relationship was found between exercise capacity and right ventricular ejection fraction or long-axis amplitude.

CONCLUSION

Resting isovolumic time is prolonged after atrial switch for patients with transposition of the great arteries. It is highly reproducible and relates well to exercise capacity.

Cardiac Intensive Care of the Adult With Congenital Heart Disease: Basic Principles in the Management of Common Problems

Although there has been an intense interest in the care of the adult with congenital heart disease (ACHD), these guidelines are usually not focused on the concepts of immediate postoperative care. The 2 most common perioperative complications are heart failure and atrial dysrhythmias. The broad etiological categories for ACHD and heart failure include primary pump failure (systolic dysfunction) and hypertrophy (diastolic dysfunction) of the right, left, or single ventricle. Some conditions with a pressure-loaded systemic right ventricle as well as patients with a functionally single ventricle may be particularly prone to develop heart failure; in others, right heart failure may occur in patients with Ebstein anomaly or with tetralogy of Fallot after corrective repair but with varying degrees of pulmonary insufficiency, and left heart failure can be a result of mitral or aortic insufficiency. The management of postoperative atrial tachycardia in the ACHD patient actually begins prior to surgery. Assessment of arrhythmia history, complete determination of risk, inducibility and arrhythmia substrate, preoperative planning of pacing sites, and optimal pacing strategies all assist to bring about optimal postoperative outcomes. Ideal perioperative care of the ACHD involves a multidisciplinary team of pediatric and adult cardiologists, pediatric and adult intensivists, cardiac surgeons, and nursing staff along with a myriad of adult subspecialists such as pulmonology, nephrology, endocrinology, and others including psychiatry.

Detection of a coronary artery anomaly after a sudden cardiac arrest in a 17 Year-old with D-transposition of the great arteries status post arterial switch operation: a case report

Long-term follow-up and testing for patients who have undergone congenital heart surgery is an evolving field. We report the case of a 17-year-old patient who had an arterial switch operation as an infant for d-transposition of the great vessels and suffered sudden cardiac arrest while participating in a cross-country event. Previous evaluations, including a cardiac catheterization and stress testing, did not indicate any identifiable abnormalities. After the arrest, a computed tomography angiogram of his chest showed an abnormal takeoff of the reimplanted left coronary artery.

Evaluation of right ventricular performance long after the atrial switch operation for transposition of the great arteries using the Doppler Tei index

Right ventricular (RV) dysfunction may occur in patients after the atrial switch operation for d-transposition of the great arteries (d-TGA) and can be an important complication. Noninvasive assessment of RV function using echocardiography is necessary for following up these patients. We evaluated RV function using the Doppler Tei index (RV Tei index). The RV Tei index measures the ratio of total time intervals in isovolumetric contraction and relaxation to the ejection time. The subjects consisted of 33 patients who had undergone the atrial switch operation for d-TGA (the atrial switch group) (mean age, 21 +/- 4 years), 10 patients with pulmonary artery stenosis after the arterial switch operation for d-TGA (the arterial switch group) (mean age, 17 +/- 1 years), and 10 patients with a normally structured heart as a control group (mean age, 26 +/- 7 years). The RV Tei index (0.65 +/- 0.16) was significantly higher in the atrial switch group than in the arterial switch group (0.29 +/- 0.07) and the control group (0.29 +/- 0.01) (p < 0.05). The fractional area change of the RV obtained from the four-chamber view in the atrial switch group showed a significant negative correlation with the RV Tei index (r = -0.58, p < 0.01). The RV Tei index increased with increasing severity of the NYHA functional class. In the moderate/severe tricuspid regurgitation group, it was significantly higher than in patients with none/trivial tricuspid regurgitation. We conclude that the RV Tei index is useful for evaluating RV junction long after the atrial switch operation for d-TGA.

Late outcome of Senning and Mustard procedures for correction of transposition of the great arteries

OBJECTIVES

To evaluate late mortality and morbidity after an atrial switch procedure for correction of transposition of the great arteries (TGA) and to assess predictive factors for adverse outcome.

SETTING

Tertiary referral centre.

DESIGN AND PATIENTS

Retrospective follow up study of 137 patients surviving hospitalisation for TGA atrial switch procedure (Mustard or Senning) in a single institution and divided into two groups (simple and complex) depending on presurgical anatomy. Several surgical and follow up factors were evaluated during 16.7 (5.6) years' follow up.

RESULTS

Late mortality was 5.1% (95% confidence interval 1.37% to 8.84%) with sudden death as the most common cause. No significant difference was found between Mustard and Senning procedures and between the complex and simple groups in terms of mortality. Independent predictive factors for late mortality were a history of supraventricular tachyarrhythmias and advanced New York Heart Association (NYHA) functional class during follow up. A very common finding was development of sinus node dysfunction (47.6%), which had no influence on mortality. There was little need for reintervention (5.1%) and relatively few cases of right ventricular systolic dysfunction (14.6%). During follow up, most patients (96.2%) were in NYHA functional class I-II.

CONCLUSIONS

Overall long term outcomes of patients with atrial repair of TGA in the present era are encouraging in terms of late mortality and quality of life. Nevertheless, better outcomes may be offered through improved diagnostic methods for right ventricular function and better management of supraventricular tachyarrhythmias.

The relationship between blood pressure, pulse pressure and right ventricular function following an atrial switch procedure for complete transposition of the great arteries

BACKGROUND

The pressure overload may be responsible for the failure of the systemic ventricle. No study so far has evaluated the association between arterial blood pressure values and right ventricular function in adults with atrially corrected complete transposition.

METHODS

This was a retrospective analysis. The studied population consisted of 60 patients with complete transposition, 11.5+/-2.7 years after atrial switch procedure, divided into subgroups according to the severity of systemic ventricular dysfunction (right ventricular ejection fraction < or = 0.40 vs. > 0.40), and the severity of perfusion abnormalities in the radionuclide study (absent or mild vs. moderate-to-severe).

RESULTS

All patients had blood pressure values (systolic 109.1+/-11.7 mm Hg and diastolic 72.3+/-9.7 mm Hg) within the normal range. Systolic blood pressure values correlated inversely with right ventricular ejection fraction (r = -0.450; p < 0.001). Compared to patients with systolic blood pressure below median values, patients with "elevated" blood pressure had lower right ventricular ejection fraction (32.6+/-6.3 vs. 38.9.+/-7.2; p < or = 0.002) and more significant perfusion abnormalities (1.5+/-1.0 vs. 2.9+/-1.5; p < or = 0.001). In a multivariate backward logistic regression model age at surgery and at the time of the study, systolic blood pressure at rest predicted impaired right ventricular ejection fraction (p < 0.02). Greater pulse pressure at peak exercise female sex were associated with greater more severe perfusion abnormalities (p < 0.01).

CONCLUSIONS

There is a significant correlation between blood pressure values and indices of right ventricular dysfunction in patients who underwent an atrial switch procedure for complete transposition. Blood pressure values might be considered as a surrogate end point in these patients.

Cardiovascular response to physical exercise in adult patients after atrial correction for transposition of the great arteries assessed with magnetic resonance imaging

OBJECTIVE

To assess with magnetic resonance imaging (MRI) cardiovascular function in response to exercise in patients after atrial correction of transposition of the great arteries (TGA).

METHODS

Cardiac function at rest and during submaximal exercise was assessed with MRI in 27 patients with TGA (mean (SD) age 26 (5) years) late (23 (2) years) after atrial correction and in 14 control participants (25 (5) years old).

RESULTS

At rest, only right ventricular ejection fraction was significantly lower in patients than in controls (56 (7)% v 65 (7)%, p < 0.05). In response to exercise, increases in right ventricular end diastolic (155 (55) ml to 163 (57) ml, p < 0.05) and right ventricular end systolic volumes (70 (34) ml to 75 (36) ml, p < 0.05) were observed in patients. Furthermore, right and left ventricular stroke volumes and ejection fraction did not increase significantly in patients. Changes in right ventricular ejection fraction with exercise correlated with diminished exercise capacity (r = 0.43, p < 0.05).

CONCLUSIONS

In patients with atrially corrected TGA, MRI showed an abnormal response to exercise of both systemic right and left ventricles. Exercise MRI provides a tool for close monitoring of cardiovascular function in these patients, who are at risk for late death.

Systemic ventricular function in patients with transposition of the great arteries after atrial repair: a tissue Doppler and conductance catheter study

OBJECTIVES

The aim of this study was to assess the utility of tissue Doppler echocardiography in the setting of repaired transposition of the great arteries when the right ventricle (RV) functions as the systemic ventricle.

BACKGROUND

Myocardial acceleration during isovolumic contraction, "isovolumic myocardial acceleration" (IVA), has been validated as a sensitive non-invasive method of assessing RV contractility. Although traditional indexes may be less valid for the abnormal RV, the relative insensitivity of IVA to an abnormal load makes it a potentially powerful clinical tool for the assessment of RV disease.

METHODS

We examined 55 controls and 80 patients (mean age 22 years) with transposition, who had undergone atrial repair at age 8 (0.3 to 72) months. A subgroup of 12 underwent cardiac catheterization. The RV systolic function was derived by analysis of pressure-volume relationships and IVA both at rest and during dobutamine stress. In all 80, myocardial velocities were sampled in the RV free wall.

RESULTS

During dobutamine (10 microg/kg/min for 10 min), the increase of IVA mirrored the increase in end-systolic elastance (r = 0.69, p < 0.02). In the group as a whole, IVA was reduced compared with the subpulmonary RV and the systemic left ventricle of controls. There was abnormal wall motion in 44 patients, which was associated with reduced IVA. Diastolic myocardial velocities were also abnormal but unrelated to the presence of wall motion abnormalities.

CONCLUSIONS

The IVA can accurately assess changes in RV contractile function in patients with an RV as the systemic ventricle. Global long-axis RV function is reduced in patients with transposition, and this is associated with abnormal regional function.

Abnormalities of right ventricular long axis function after atrial repair of transposition of the great arteries

BACKGROUND

While volume derived global indices of right ventricle (RV) function are frequently abnormal after the Mustard procedure, the mechanism for these abnormalities is poorly understood. RV muscle fibres are predominantly arranged longitudinally and thus indices derived in the long axis may better describe RV function.

METHODS

20 survivors of the Mustard operation were studied (age 7.8–37.3 years, median 14.2 years). Long axis recordings from the apical four chamber view were obtained with the M mode cursor positioned through the lateral angle of the tricuspid valve annulus. M mode traces were recorded on paper and later digitised to derive total atrioventricular ring excursion, peak lengthening rate, and peak shortening rate. These data were averaged and compared with control data for the normal RV and left ventricle (LV).

RESULTS

RV total atrioventricular ring excursion was lower than that for the RV (p < 0.0001) or LV (p < 0.005) of controls. Peak lengthening rate was lower than the normal RV (p < 0.0001) and LV (p < 0.0001) rates. Furthermore, peak shortening rate was less than that of normal RV (p < 0.0001) and normal LV (p < 0.005) controls.

CONCLUSION

Systemic RV long axis function is notably reduced compared with that of either the normal subpulmonary RV or the systemic LV. This presumably reflects the response of the predominantly longitudinally arranged myocardial fibres to increased afterload. However, such measurements may provide a more sensitive marker for progressive changes in global function during long term follow up.

Abnormalities of right ventricular long axis function after atrial repair of transposition of the great arteries

BACKGROUND

While volume derived global indices of right ventricle (RV) function are frequently abnormal after the Mustard procedure, the mechanism for these abnormalities is poorly understood. RV muscle fibres are predominantly arranged longitudinally and thus indices derived in the long axis may better describe RV function.

METHODS

20 survivors of the Mustard operation were studied (age 7.8-37.3 years, median 14.2 years). Long axis recordings from the apical four chamber view were obtained with the M mode cursor positioned through the lateral angle of the tricuspid valve annulus. M mode traces were recorded on paper and later digitised to derive total atrioventricular ring excursion, peak lengthening rate, and peak shortening rate. These data were averaged and compared with control data for the normal RV and left ventricle (LV).

RESULTS

RV total atrioventricular ring excursion was lower than that for the RV (p < 0.0001) or LV (p < 0.005) of controls. Peak lengthening rate was lower than the normal RV (p < 0.0001) and LV (p < 0.0001) rates. Furthermore, peak shortening rate was less than that of normal RV (p < 0.0001) and normal LV (p < 0.005) controls.

CONCLUSION

Systemic RV long axis function is notably reduced compared with that of either the normal subpulmonary RV or the systemic LV. This presumably reflects the response of the predominantly longitudinally arranged myocardial fibres to increased afterload. However, such measurements may provide a more sensitive marker for progressive changes in global function during long term follow up.

Myocardial flow reserve in patients with a systemic right ventricle after atrial switch repair

OBJECTIVES

The purpose of this study was to assess myocardial blood flow (MBF) and flow reserve in systemic right ventricles (RV) in long-term survivors of the Mustard operation.

BACKGROUND

There is a high prevalence of systemic RV dysfunction and impaired exercise performance in long-term survivors of the Mustard operation. A mismatch between myocardial blood supply and systemic ventricular work demand has been proposed as a potential mechanism.

METHODS

We assessed MBF at rest and during intravenous adenosine hyperemia in 11 long-term survivors of a Mustard repair (age 18+/-5 years, median age at repair 0.7 years, follow-up after repair 17+/-5 years) and 13 healthy control subjects (age 23+/-7 years), using N-13 ammonia and positron emission tomography imaging.

RESULTS

There was no difference in basal MBF between the systemic RV of survivors of the Mustard operation and the systemic left ventricle (LV) of healthy control subjects (0.80+/-0.19 vs. 0.74+/-0.15 ml/g/min, respectively, p = NS). However, the hyperemic flows were significantly lower in systemic RVs than they were in systemic LVs (2.34+/-0.0.69 vs. 3.44+/-0.62 ml/g/min respectively, p < 0.01). As a result, myocardial flow reserve was lower in systemic RVs than it was in systemic LVs (2.93+/-0.63 vs. 4.74+/-1.09, respectively, p < 0.01).

CONCLUSIONS

Myocardial flow reserve is impaired in systemic RVs in survivors of the Mustard operation. This may contribute to systemic ventricular dysfunction in these patients.

Long-term assessment and serial evaluation of cardiorespiratory exercise performance and cardiac function in patients with atrial switch operation for complete transposition

BACKGROUND

At present, a considerable number of patients survive who underwent an atrial switch operation for correction of complete transposition. Our study aimed to assess their long-term exercise performance and the serial evolution of cardiac function.

METHODS

We studied 22 patients 5 to 17 years after an atrial switch operation, and followed them serially for 3.5 +/- 2 years after the first evaluation. Cardiorespiratory exercise function was assessed by analysis of gas exhange and by determination of the ventilatory anaerobic threshold. Echocardiography was performed on all evaluations.

RESULTS

All patients were in Class I of the classification of the New York Heart Association at all assessments. Ventilatory anaerobic threshold, however, was significantly lower than normal. It averaged 77.9% +/- 13.7 of the normal mean value at the initial evaluation, and remained stable when re-evaluated later (76.2 +/- 13.7%). At the initial study, the increase in oxygen uptake during graded exercise was below the 95% confidence limit in 6 of the patients, and was below this level in 10 patients at re-assessment. The subnormal values for oxygen uptake during submaximal exercise were associated with moderate to severe haemodynamic dysfunction. At echocardiography, 15 of 17 patients studied twice had mild to moderate right ventricular dilation and tricuspidregurgiation, which remained virtually the same at reasssesment. A stable sinus rhythm was initially present in 17 patients, and persisted in 15 patients during follow-up.

CONCLUSION

At medium term follow-up, cardiorespiratory exercise performance remains stable in patients after atrial switch repair. Serial exercise testing appears useful, because in individual patients in the present study, a decreasing exercise tolerance correlated with development of haemodynamic sequels.

Long-term outcome after the mustard repair for simple transposition of the great arteries. 28-year follow-up

OBJECTIVES

This study examines the late outcome in patients with simple transposition of the great arteries (TGA) after a Mustard operation.

BACKGROUND

Continuing medical follow-up for patients after the Mustard procedure, now extending to three decades, is required. The quality of life of adult survivors has not been well documented.

METHODS

Survival and quality of life among 113 hospital survivors of the Mustard operation performed for simple TGA between 1964 and 1982 were assessed by medical review and a lifestyle questionnaire. The incidence of right ventricular failure and echocardiographic right ventricular dysfunction (RVD) were determined. A measure of lifestyle, the ability index, was determined.

RESULTS

Actuarial survival was 90%, 80%, and 80% at 10, 20, and 28 years, respectively, with 76% of survivors being New York Heart Association class 1. Sudden death, with an incidence of 7% without identifiable risk factors, was the most common cause of late demise. RVD was identified in 18% of patients who had echocardiography, but there was right ventricular failure in only two patients. Seventy-five percent of current survivors lead a normal life, 20% have some symptoms or lifestyle modification, and 5% are unable to work.

CONCLUSIONS

The survival of patients to 28 years with the Mustard repair has been good. Late sudden death is the most worrisome feature. There is a 97% freedom from right ventricular failure to date. The quality of life of late survivors is good, most achieving a normal level of education and employment.

Long-term ventricular performance after intra-atrial correction of transposition: left ventricular filling is the major limitation

OBJECTIVE

To establish the incidence of systolic and diastolic dysfunction of the right and left ventricle in a large cohort of patients after Mustard or Senning operations and to assess changes in the incidence on long term follow up.

DESIGN

Postoperative case-control study using radionuclide ventriculography. Ejection fractions, peak filling rates, rapid filling periods and fractions, slow filling periods and fractions, and atrial contraction periods and fractions were studied.

SETTING

Tertiary care centre, ambulatory and hospital inpatient care.

PATIENTS

A convenience sample of 153 patients studied at median age of 6.9 years (median 4.4 years after surgery). In 99 cases another study was available at a median age of 15.3 years (median 13 years after surgery and 8.8 years after the first study).

RESULTS

Respective incidences of dysfunction in the first and the second study were as follows: ejection fraction-right ventricle 7.8% and 8.1%, left ventricle 7.2% and 10.1%: peak filling rate-right ventricle 0% and 4.2%, left ventricle 14.3% and 29.5% (p < 0.05); rapid filling period-right ventricle 18.3% and 11.6%, left ventricle 30.2% and 30.5%; slow filling period-right ventricle 4.8% and 3.2%; left ventricle 11.9% and 23.2%; atrial contraction period-right ventricle 0.8% and 4.2%, left ventricle 15.1% and 26.3%; rapid filling fraction-right ventricle both 0%, left ventricle 82.5% and 79.0%; slow filling fraction-right ventricle 0.8% and 4.2%, left ventricle 37.3% and 30.5%; atrial contraction fraction-right ventricle both 0%, left ventricle 79.4% and 71.6%.

CONCLUSIONS

The incidence of systolic ventricular dysfunction is 8% (right ventricle) and 10% (left ventricle) 13 years after surgery, without a significant increase over the eight year follow up. Diastolic filling is abnormal in up to 80% of patients and left ventricular peak filling rate deteriorates with time.

Cardiorespiratory response to exercise after venous switch operation for transposition of the great arteries

STUDY OBJECTIVES

This study reports on the cardiorespiratory response to graded exercise in patients after venous switch operation for transposition of the great arteries.

DESIGN

Several small studies have documented a diminished exercise tolerance after Mustard repair for transposition of the great arteries, little information exists, however, about long-term cardiorespiratory exercise performance in patients who have had the Senning procedure.

PATIENTS

This prospective study reports on the serial long-term (mean, 11 +/- 2.8 years) cardiopulmonary exercise performance of 43 patients (age, 12 +/- 3.1 years) who underwent a Senning procedure, with no significant postoperative abnormalities. Forty-three matched healthy children were also studied as a control group.

MEASUREMENTS AND RESULTS

All underwent exercise testing (Bruce protocol) with metabolic gas exchange to determine parameters at 3 min, anaerobic threshold, similar heart rate (150 beats/min), and peak exercise. Time of exercise was 10.5 +/- 1.9 min in patients and 13.4 +/- 2 min in control subjects (p = 0.0001). Overall, patients reached 73% of peak oxygen uptake achieved by control subjects (32.6 +/- 5.6 vs 44.7 +/- 6 mL/kg/min). Chronotropic response (188 +/- 15.7 vs 166.5 +/- 19.6 beats/min [p = 0.0001]) and oxygen pulse (7.4 +/- 2.9 vs 10.7 +/- 4.2 mL/beat [p = 0.0002]) were lower in patients at peak exercise. Patients had a greater respiratory response to exercise: both respiratory rate and ventilatory equivalent for carbon dioxide were significantly higher at all stages of exercise. Exercise capacity assessed by peak oxygen uptake was correlated with time elapsed since surgical repair (r = 0.48; p = 0.001).

CONCLUSIONS

It is concluded that even in asymptomatic patients, exercise endurance and respiratory response are generally altered as much as 11 +/- 2.8 years after venous switch operation, although early surgical repair is predictive of a better long-term functional result.

Long-term follow-up (10 to 17 years) after Mustard repair for transposition of the great arteries

BACKGROUND

The management strategies of patients who underwent Mustard repair for transposition (of the great arteries were changed in the 1970s: infants became eligible for direct surgical repair, so Blalock-Hanlon atrioseptostomy could be avoided, and cold cardioplegia was introduced for myocardial preservation. Data are lacking, however, regarding whether these changes have had positive effects on the long-term outcome. We therefore conducted a follow-up study on all 91 patients who underwent a Mustard repair for transposition of the great arteries in our institution between 1973 and 1980 to assess the incidence and clinical importance of sequelae as well as health-related quality of life for these patients.

METHODS

Patients who were alive and could be traced through local registrar's offices received an invitation to participate in the follow-up study, which consisted of an interview, physical examination, echocardiography, exercise testing, and standard 12-lead and 24-hour electrocardiography.

RESULTS

Patients operated on in the first 4 years had a significantly higher mortality rate and higher incidence of sinus node dysfunction than did patients operated on in the subsequent 4 years (25% vs 2% and 41% vs 3%, respectively). In contrast, the incidence of baffle obstruction necessitating reoperation was significantly higher in the second group. There were no significant differences in echocardiographic findings and exercise capacity between patients operated on in the first 4 years and in the subsequent 4 years. None of the patients had right ventricular failure; a mild degree of baffle leakage or obstruction was seen in 22% of the patients, and the mean exercise capacity was decreased to 84% +/- 16% of normal.

CONCLUSION

The changes introduced between 1973 and 1980 have resulted in a considerable reduction of mortality and incidence of sinus node dysfunction but have also resulted in a more frequent need for reoperation.

Right ventricular systolic function in adolescents and young adults after Mustard operation for transposition of the great arteries

This study evaluates long-term ( > 10 years since surgery) right ventricular (RV) systolic function in patients who had previously undergone intraatrial baffle surgery for transposition of the great arteries. Studies suggest these patients are clinically stable and lead satisfactory lifestyles, but long-term ventricular performance is not known. Radionuclide angiocardiography was used to estimate RV ejection fraction in 58 patients a mean of 14 years after the Mustard operation. Repeat studies were performed in 32 patients. The absolute RV ejection fraction of 0.53 +/- 0.10 in our patients did not differ from normal values. Nine patients had a value < 0.42, placing them > 2 SDs below normal. Repeat RV ejection fraction decreased from 0.54 +/- 0.11 to 0.51 +/- 0.11 (p < 0.1) in 32 patients, and > 0.10 in 6. Thus, RV ejection fraction was abnormal in 9 of 58 patients (16%) evaluated > 10 years after a Mustard operation. Repeat studies demonstrate worsening in at least 6 of 32 patients (19%). These postoperative Mustard patients require continued evaluation, even in the absence of overt symptomatology.

Right ventricular performance and mass by use of cine MRI late after atrial repair of transposition of the great arteries

BACKGROUND

The long-term adaptation of the right ventricle after atrial repair of transposition of the great arteries (TGA) remains a subject of major concern. Cine magnetic resonance imaging (MRI), with its tomographic capabilities, allows unique quantitative evaluation of both right and left ventricular function and mass. Our purpose was to use MRI and an age-matched normal population to examine the typical late adaptation of the right and left ventricles after atrial repair of TGA.

METHODS AND RESULTS

Cine MRI was used to study ventricular function and mass in 22 patients after atrial repair of TGA. Images were obtained in short-axis sections from base to apex to derive normalized right and left ventricular mass (RVM and LVM, g/m2), interventricular septal mass (IVSM, g/m2), RV and LV end-diastolic volumes (EDV, mL/m2), and ejection fractions (EF). Results 8 to 23 years after repair were compared with analysis of 24 age- and sex-matched normal volunteers and revealed markedly elevated RVM, decreased LVM and IVSM, normal RV size, and only mildly depressed RVEF. Only 1 of 22 patients had clinical RV dysfunction, and this patient had increased RVM.

CONCLUSIONS

Cine MRI allows quantitative evaluation of both RV and LV mass and function late after atrial repair of TGA. Longitudinal studies that include these measurements should prove useful in determining the mechanism of late RV failure in these patients. On the basis of these early data, inadequate hypertrophy does not appear to be the cause of late dysfunction in this patient group.

Quantification of right ventricular function with magnetic resonance imaging in children with normal hearts and with congenital heart disease

In clinical treatment of children with congenital heart disease (CHD) assessment of right ventricular (RV) function is important. Available imaging techniques have been of limited value because of technical factors and the complex geometry of the right ventricle. To validate magnetic resonance (MR) imaging measurements of RV function in children, gradient echo MR imaging of both ventricles and MR flow mapping of great vessel and tricuspid flow was performed in 20 children with CHD affecting the right ventricle and in 22 healthy children ranging in age from 5 to 16 years. Close correlation between RV versus LV stroke volumes (r = 0.96) and RV stroke volume versus great artery (r = 0.97) or tricuspid flow (r = 0.97) was observed with small interobserver and intraobserver variability. Results of healthy children were end-diastolic volume: 70 +/- 9 ml/m2, end-systolic volume: 21 +/- 5 ml/m2, and ejection fraction: 70% +/- 4%. In the patient groups clinically important differences were noted. We conclude that MR imaging provides accurate noninvasive measurements of RV function in healthy children and patients with (operated) CHD.

Right and left ventricular performance 10 years after Mustard repair of transposition of the great arteries

Twenty-two late survivors of Mustard repair of transposition of the great arteries underwent treadmill exercise testing to assess exercise endurance, and radionuclide cineangiography to measure rest and exercise right ventricular (RV) and left ventricular (LV) ejection fraction (EF). Mean age at Mustard repair was 1.8 +/- 2.4 years and at initial exercise study 14.1 +/- 4.5 years. All patients were asymptomatic at study entry. Treadmill endurance time (9 to 12 minutes) was within the normal range for age in 18 of 20 patients. LVEF and RVEF at rest were within normal limits (55 +/- 8% and 52 +/- 9%, respectively). All LVEFs and RVEFs during exercise were also within the normal range (64 +/- 8% and 57 +/- 9%, respectively). However, the magnitude of increase in EF (rest to exercise) was subnormal for the right ventricle in 7 patients and for the left ventricle in 2 patients. Exercise RVEF was higher in patients with simple transposition who underwent repair at < 1 year of age than in those who underwent operation at age > 1 year (62 +/- 10% vs 52 +/- 7%). Serial study in 6 patients revealed no change in average RVEF or LVEF after an average interval of 4.4 years. One patient with complex transposition subsequently developed refractory congestive heart failure requiring cardiac transplantation. It is concluded that exercise endurance and LVEF and RVEF at rest and exercise are generally well preserved up to 19 years after Mustard repair, particularly in cases of simple transposition of the great arteries repaired before 1 year of age.

Cardiorespiratory exercise performance after Senning operation for transposition of the great arteries

OBJECTIVE

To assess the cardiorespiratory response to graded exercise in patients after the Senning operation for transposition of the great arteries.

DESIGN

Cross sectional study. Exercise performance was assessed by determination of the ventilatory anaerobic threshold. This was defined as the exercise intensity at which the ventilatory equivalent for oxygen (VE/VO2) started to increase systematically without a concomitant increase in the ventilatory equivalent for carbon dioxide (VE/VCO2).

SETTING

Outpatient department.

PATIENTS

Sequential sample of 20 patients studied 5-10 years (mean 7.3 years) after the Senning operation. Age at exercise testing varied from 5 to 11 (mean 7.8) years.

RESULTS

The ventilatory threshold in the patients was significantly lower than normal (p < 0.005) and averaged 79.3% (SD 13%) and 80% (12%) of the predicted normal value for age and weight, respectively. Also, the ventilatory threshold was surpassed sooner (mean 3.2 (range 2-5) minutes) in the patients than in normal controls (3.9 (2.6-4.6) minutes). The lower ventilatory threshold was associated with a subnormal oxygen uptake (ml/min/kg) during submaximal exercise, a higher than normal ventilatory equivalent for oxygen ratio, and a lower end tidal carbon dioxide tension in the patients compared with normal controls. In half of the patients heart rate was lower during graded exercise. This relative bradycardia was not associated with a normal ventilatory threshold, as often seen in fit young people. No major disturbances in rhythm were observed during exercise.

CONCLUSION

Exercise performance, assessed by respiratory gas exchange, was slightly but significantly lower than normal in patients after the Senning operation. A subnormal ventilatory threshold, associated with a higher than normal ventilatory response during submaximal exercise, supports the hypothesis that oxygen delivery to tissues is slightly impaired in these patients.

Functional assessment of the heart after corrective surgery for complete transposition

SummaryThe justification for the introduction of the arterial switch procedure was based, primarily, on concern regarding the long-term ability of the right ventricle to perform as the systemic pumping chamber. In this article, the functional performance of both the systemic and pulmonary ventricles after atrial redirection procedures and the arterial switch operation will be discussed.

Right ventricular function 10 years after the Mustard operation for transposition of the great arteries: analysis of size, shape, and wall motion

Biplane right ventriculograms were obtained in 18 symptom free patients 109 (26) months (mean (SD)) after Mustard repair of transposition of the great arteries. Ventricular size, shape, and wall motion were measured from the digitised angiograms and compared with previously published data on left ventricular function after anatomical correction of transposition of the great arteries, with right ventricular function in controls, and with patients before repair of tetralogy of Fallot. Global indices of ventricular function were depressed after Mustard repair and wall motion abnormalities were common. The presence of wall motion abnormalities in this group was associated with a reduction in ejection fraction and ventricular filling rates. In four of five patients in whom an appropriate preoperative angiogram was available a similar pattern of wall motion was seen before the Mustard operation, suggesting that preoperative events may be important in determining eventual outcome.