Functional status of patients with large ventricular septal defect and pulmonary vascular disease 6 to 16 years after surgical closure of their defect in childhood

Outcomes of infants and children undergoing surgical repair of ventricular septal defect: a review of the literature and implications for research with an emphasis on pulmonary artery hypertension

BACKGROUND

Pulmonary vascular disease resulting from CHDs may be the most preventable cause of pulmonary artery hypertension worldwide. Many children in developing countries still do not have access to early closure of clinically significant defects, and the long-term outcomes after corrective surgery remain unclear. Focused on long-term results after isolated ventricular septal defect repair, our review sought to determine the most effective medical therapy for the pre-operative management of elevated left-to-right shunts in patients with an isolated ventricular septal defect.

METHODS

We identified articles specific to the surgical repair of isolated ventricular septal defects. Specific parameters included the pathophysiology and pre-operative medical management of pulmonary over-circulation and outcomes.

RESULTS

Studies most commonly focused on histologic changes to the pulmonary vasculature and levels of thromboxanes, prostaglandins, nitric oxide, endothelin, and matrix metalloproteinases. Only 2/44 studies mentioned targeted pharmacologic management to any of these systems related to ventricular septal defect repair; no study offered evidence-based guidelines to manage pulmonary over-circulation with ventricular septal defects. Most studies with long-term data indicated a measurable frequency of pulmonary artery hypertension or diminished exercise capacity late after ventricular septal defect repair.

CONCLUSION

Long-term pulmonary vascular and respiratory changes can occur in children after ventricular septal defect repair. Research should be directed at providing an evidenced-based approach to the medical management of infants and children with ventricular septal defects (and naturally all CHDs) to minimise consequences of pulmonary artery hypertension, particularly as defect repair may occur late in underprivileged societies.

Hemodynamic Evaluation of Children with Persistent or Recurrent Pulmonary Arterial Hypertension Following Complete Repair of Congenital Heart Disease

Persistent or recurrent pulmonary arterial hypertension (PAH) following complete surgical repair of congenital heart disease (CHD) represents one of the largest group of PAH associated with CHD (PAH-CHD) in recent registry studies and seems to have a particularly poor prognosis. However, little is known about this fourth clinical subclass of PAH-CHD, especially in children. The purpose of this study was to assess specific characteristics of invasive hemodynamics of this disease in children, including acute vasodilator testing (AVT) and pulmonary endothelial function (PEF) and to compare to patients with idiopathic PAH (IPAH), who usually present with a similar fatal clinical course. Thirty-two children with PAH were included in the study, twelve of these patients had PAH-CHD subclass 4 (mean age 8.0 ± 3.4 years) and twenty children had IPAH (mean age 8.6 ± 4.4 years). Cardiac catheterization was performed in all children, including AVT and PEF. PEF was assessed by changes in pulmonary blood flow in response to acetylcholine (Ach) using Doppler flow measurements. Pulmonary flow reserve (PFR) was calculated as the ratio of pulmonary blood flow velocity in response to Ach relative to baseline values. At baseline, the ratio of mean PA pressure to mean systemic arterial pressure (mPAP/mSAP) was comparably high in both groups (0.78 ± 0.32 vs. 0.80 ± 0.22), while the indexed pulmonary vascular resistance (PVRI) was significantly lower in the PAH-CHD group (12.6 ± 6.8 WUxm²) compared to IPAH patients (19.9 ± 10.6 WUxm²) (p = 0.04). Cardiac index was significantly higher in the PAH-CHD group (4.19 ± 1.09 l/min/m² vs. 3.23 ± 0.76) (p = 0.017). However, AVT revealed a significantly larger maximum response (percentage of fall of PVR/SVR ratio during AVT) in the IPAH group (37 ± 22%) compared to the PAH-CHD group (13 ± 23%) (p = 0.017). PEF showed no significant difference between both patient groups (PFR 1.69 ± 0.71 vs. 1.73 ± 0.68) (p = 0.76). Our study demonstrates significant pulmonary vascular disease in children with persistent or recurrent PAH following complete surgical repair of CHD similar to IPAH patients. Although baseline measures appeared to be more favorable, pulmonary vasoreactivity was markedly impaired in PAH-CHD subclass 4, which may contribute to its negative impact on the long-term outcome of this patient group.

Long term results after operative treatment of isolated ventricular septal defect in adolescents and adults

A series of 125 consecutive patients with isolated ventricular septal defect (VSD) aged 10 or over, were followed until death or beyond the age of 30 (31-73) years. A prospective restudy was performed after a mean follow-up of 15 (3-21) years. Forty-one patients (group 1) were treated with surgical repair of VSD at a mean age of 23 (10-51) years, and early mortality was 10%, i.e. 3 with severe aortic insufficiency and one with systemic pulmonary artery pressure. Surgery was initially not regarded indicated in 70 patients with small defects (group 2). A further 14 patients were judged inoperable (group 3). Long-term mortality was 5% in group 1, 9% in group 2 and 71% in group 3. When restudied, group 2 patients had significantly higher (p less than 0.01) and group 1, lower (p less than 0.01) pulmonary artery pressures than initially. A moderate deterioration in NYHA-rating was noted in group 2 (p less than 0.05) vs. a slight improvement in group 1 (p less than 0.05). The non-operated patients had a higher incidence of valvular lesions (19% vs. 13%) and bacterial endocarditis (4.3% vs. 2.7%) than the operated but not to a statistically significant level. Spontaneous closure was 6% in group 2 whereas mostly small residual defects were found in 34% of the operated. Patients with uncomplicated VSDs (absence of valvular lesions or coronary heart disease) had subnormal exercise tolerance as judged from a standardized ergometer bicycle test. These patients also had impaired left ventricular function based upon haemodynamic studies during moderate supine exercise. No major differences were noted between groups 1 and 2, but operated patients with residual VSDs tended to have the poorest cardiac performance. Non-cardiac disease represented only a minor problem and no significant differences in psychosocial function were observed between groups 1 and 2. Only 50% in group 1 and 60% in group 2 attended a regular medical clinic. Antibiotic prophylaxis had only been practiced by 50% in both groups. Although small, but differences between groups 1 and 2 favour surgery. This must be regarded as a positive result of surgical treatment since those operated on had basically larger and thus more severe defects than the others. In view of the very low operative risk associated with modern surgical technique one should direct patients with significant shunts to operative treatment.

Vascular remodeling process in reversibility of pulmonary arterial hypertension secondary to congenital heart disease

Pulmonary vascular remodeling process was analyzed using morphometry in lung biopsy specimens taken from 26 children, aged 6 to 160 months, who had congenital heart disease and significant pulmonary arterial hypertension. Reparative surgery was performed in 22 patients and palliative surgery was performed in four patients. One patient expired postoperatively and four others after hospital discharge. Vascular remodeling examination revealed a characteristic pathological picture: pronounced medial thickening with increased collagen content (fibrosis), without significant arterial intimal proliferation. At a mean follow-up of 44 months, 72% of the survivors were asymptomatic with no medication. Diagnosed by echocardiogram, 22% of these patients were shown to have pulmonary arterial hypertension. The characteristic pathological features described above occurred in 38% of the patients who either expired or had pulmonary hypertension postoperatively. These findings were an aid to identifying a high risk group in which the outcome does not meet expectations for the classical grade I and II changes. We concluded that the presence of isolated medial thickening does not ensure either survival or a normal postoperative pulmonary arterial pressure at late follow-up and that the collagen content can be a better reference for good outcome. Early intracardiac repair is recommended before the development of significant medial fibrosis.

Pulmonary vascular resistance during exercise late after repair of large ventricular septal defects. Relation to age at the time of repair

Postoperative pulmonary artery pressure and resistance were assessed during exercise in 32 patients late after repair of large ventricular septal defect with pulmonary hypertension. Nineteen patients had a preoperative pulmonary-to-systemic resistance ratio of between 0.15 and 0.50 (group 1) and 13 had a ratio between 0.50 and 0.96 (group 2). Age at the time of operation was 0.9 to 13.0 years (4.6 +/- 3.6) in group 1 and 0.8 to 15.8 years (4.3 +/- 4.2) in group 2. Age at the time of restudy was 9 to 21 years (14.5 +/- 3.0) in group 1 and 9 to 22 years (13.5 +/- 4.1) in group 2. Pulmonary artery pressure was measured in the supine position at rest and during exercise, as were the measurements underlying the calculations of pulmonary vascular resistance. Mean pulmonary artery pressure was 13 to 21 mm Hg (17 +/- 2) and 10 to 26 mm Hg (20 +/- 5) in groups 1 and 2, respectively, at rest, and this increased to 17 to 27 mm Hg (22 +/- 3) and 14 to 39 mm Hg (27 +/- 7) in groups 1 and 2, respectively, during exercise (p < 0.05). Pulmonary vascular resistance was 0.51 to 3.40 U.m2 (1.93 +/- 0.63) and 0.79 to 3.31 U.m2 (2.05 +/- 0.65) in groups 1 and 2 at rest. It was 0.58 to 2.24 U.m2 (1.36 +/- 0.57) and 0.81 to 3.85 U.m2 (2.18 +/- 0.97) in groups 1 and 2 during exercise (p < 0.01). Postoperative pulmonary vascular resistance during exercise correlated well with age at the time of repair in both groups (r = 0.65, p < 0.05 in group 1; r = 0.86, p < 0.001 in group 2). These data suggest that 85% of patients with a preoperative pulmonary-to-systemic resistance ratio of between 0.15 and 0.50 would have normal pulmonary vascular resistance during exercise when operated on at younger than 3.8 years old and 85% of those with a preoperative pulmonary-to-systemic resistance ratio of more than 0.50 would have normal pulmonary vascular resistance during exercise when operated on at younger than 1.1 years.

Late results (30 to 35 years) after operative closure of isolated ventricular septal defect from 1954 to 1960

This study was designed to determine the clinical status, cause of death, and effects of pulmonary vascular disease and conduction abnormalities 30 to 35 years after surgery in 296 consecutive surviving patients of closure of ventricular septal defect. Of the 296 patients, current status was determined by contact with patient and physician in 290 cases, with 6 (2%) lost to follow-up (7,912 patient years are included). Cardiac catheterization after surgery in 168 patients showed complete closure of the defect in 80%. Death occurred in 59 patients (20%), with higher mortality rates in those operated on after the age of 5 years, those with pulmonary vascular resistance greater than 7 units (51%), and those with complete heart block (78%). Of 37 patients with transient heart block after surgery, 8 (22%) have died (3 pulmonary vascular disease, 2 sudden death, 2 unknown causes and 1 complete heart block). Twenty other patients had a dysarrhythmia after surgery, and none of these died. Nine episodes of endocarditis occurred (11.4/10,000 patient years). Nine of 296 (3%) offspring had cardiac malformation. Most patients are in New York Heart Association class I, 57% attended college and 15% received an advanced degree. The data show good results for this group of patients operated on during an early era (1954 to 1960) of open cardiac surgery. They support the current trend toward operation in patients with ventricular septal defects at an early age and with low pulmonary vascular resistance.

Comparison of cardiovascular adjustments to exercise in adolescents 8 to 15 years of age after correction of tetralogy of fallot, ventricular septal defect or atrial septal defect

Surgical correction of tetralogy of Fallot (TF) has generally been associated with a reduced maximal exercise tolerance, possibly related to the ventriculotomy inherent to the intracardiac repair procedure. This study documents the exercise hemodynamics of a group of patients operated on for TF who showed similar clinical and functional characteristics, and compares these responses to those of age-matched patients operated on for an isolated ventricular septal defect (VSD) or atrial septal defect (ASD) in an attempt to better understand the role of the ventriculotomy in the exercise limitation. Thirty patients, ages 12 to 19 years, operated on before 5 years of age for complete repair of TF (n = 13), VSD (n = 7) or ASD (n = 10) and 10 age-matched control subjects underwent a progressive maximal cycling test to determine the maximal oxygen uptake (VO2 max), and completed submaximal cycling at intensities of 33 and 66% VO2 max, respectively, to determine the cardiac output (CO2-rebreathing). No significant differences in VO2 max were observed (TF = 37.6 +/- 10; VDS = 34.0 +/- 9.2; ASD = 36.5 +/- 7; controls = 41.3 +/- 6.0 ml/kg/min). The maximal heart rate, however, remained lower in all patient groups in comparison with control subjects (p less than or equal to 0.05) (TF = 178 +/- 14; VSD = 172 +/- 17; ASD = 179 +/- 16; controls = 191 +/- 12 beats/min).(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise after surgical repair of congenital cardiac lesions

Congenital heart defects arise in approximately 1% of all live births, independent of ethnic and geographical considerations. With the development of new surgical procedures and current technologies a large number of these heart lesions can be surgically corrected in infancy. In the majority of cases patients evaluated some 10 to 20 years after surgery are asymptomatic and can lead a normal life. Despite their satisfactory clinical outcome patients may, nevertheless, show an abnormal pattern of physiological responses when submitted to dynamic exercise. This paper reviews the scientific literature concerning the exercise capabilities and the cardiorespiratory adjustments to exercise in patients surgically corrected for 4 of the most common congenital heart lesions: isolated atrial septal defect, isolated ventricular septal defects, pulmonary stenosis and tetralogy of Fallot. The maximal exercise tolerance of postoperative congenital heart defect patients may usually be related to: (a) the age of the patients at the time of surgery; (b) the severity of the lesions remaining after surgery; and (c) the age of the patients at the time of investigation. Although normal maximal exercise capabilities may be found in a good number of patients operated for either of the 4 lesions considered, this does not imply normal exercise haemodynamics. A general observation made in these 4 groups of patients is that of a subnormal exercise cardiac output which may or may not be fully compensated by an increase in peripheral oxygen extraction. The limitation in exercising cardiac output may, in turn, be attributed to either a subnormal stroke volume or a limitation in the chronotropic response to exercise or a combination of both factors. Residual pulmonary stenosis, increased pulmonary vascular resistance, increased myocardial stiffness are all factors that may contribute to the cardiac output limitation. A thorough explanation of underlying causes for the abnormal haemodynamic response to exercise, however, still remains to be provided.

Pulmonary vascular disease in ventricular septal defect: structural and functional correlations in lung biopsies from 85 patients, with outcome of intracardiac repair

Pulmonary vascular structure was analysed using morphometric techniques, and arterial wall abnormalities in lung biopsy specimens taken from 85 cases of ventricular septal defect, aged 3 weeks to 30 years were described. The defect was closed in 53 patients, 12 died at operation and 11 survivors were recatheterized. Structural examination revealed a characteristic pathological picture which appeared to precede classical grade IV pulmonary vascular disease. This predilatation phase was identified by finding pre-acinar obstructive intimal proliferation or fibrosis, associated with only a slight increase in intra-acinar arterial muscularity, in the absence of stigmata of grade IV disease in patients with a pulmonary resistance greater than 6 units m2. Predilatation features occurred in 62 per cent of patients who either died at repair or who had post-operative pulmonary hypertension. These findings help identify a high risk group in whom resistance is higher than expected in the absence of classical grade IV changes. In addition, a marked increase in muscularity without intimal obstruction can also be associated with a pre-operative resistance of more than 6 units m2. The presence of medial hypertrophy only does not ensure either survival or a normal post-operative pulmonary arterial pressure. Early intra-cardiac repair is recommended before obstructive intimal fibrosis develops during the second year.

Pulmonary arterial changes in patients with ventricular septal defects and severe pulmonary hypertension

In 25 patients, aged eight months to 31 years, with ventricular septal defect (VSD; isolated in 15, the others with atrial septal defect, PDA, coarctation or patent ductus arteriosus + coarctation), each with severe pulmonary artery hypertension (pulmonary artery systolic pressure [Ppa] at least 75% of systemic and an elevated pulmonary vascular resistance), we related morphologic and morphometric data from open-lung biopsy to hemodynamic measurements obtained at cardiac catheterization during the same hospital admission. Of the hemodynamic features measured, only the ratios of pulmonary-to-systemic flow and pulmonary-to-systemic resistance correlated significantly with structure. Neither pulmonary artery pressure (Ppa) nor pulmonary vascular resistance correlated significantly with any structural feature studied. The increased external diameter of respiratory bronchiolar arteries in those with the more advanced Heath-Edwards grades reflects dilatation and suggests that it is in the small arteries of the distal arterial bed that the changes of pulmonary hypertension are most significant. Neither age nor body weight correlated significantly with the degree of structural or hemodynamic abnormality. In the ten patients who underwent VSD closure, Ppa was measured postoperatively. The Heath-Edwards grade (no more than one grade-III lesion) and arterial density (at least one-half that normal for age) were the best correlates of the difference between preoperative Ppa and Ppa immediately after corrective surgery. The presurgical catheterization data, including pulmonary resistance and the resistance ratio, did not correlate significantly with change in Ppa following VSD closure.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamic findings at rest and during mild supine exercise in adults with isolated, uncomplicated ventricular septal defects

Fifty-two patients with isolated congenital ventricular septal defects (VSDs), studied for the first time at age 10 or older, were restudied an average of 16 years later (range 4 to 21). The study protocol included a symptom-limited bicycle ergometer test, M mode echocardiographic examination, and hemodynamic studies at rest and during mild supine exercise. Of the 52, 17 had been operated on an average of 19 years earlier (range 11 to 21) (group 1) and 35 with smaller defects were not operated on (group 2). Although more pronounced findings were made in group 1, a similar pattern was observed in group 2: In most subjects in both groups a subnormal working capacity was observed. A subnormal left ventricular fractional shortening and circumferential shortening velocity was noted in a high proportion at echocardiography. A number of hemodynamic aberrations were observed in a high proportion of patients during exercise but not at rest. Thus a subnormal increase in left and right ventricular cardiac output was found in addition to pathologic increase in right and left ventricular end-diastolic, pulmonary arterial, and pulmonary capillary wedge pressures. In group 1, elevated pulmonary arterial pressures before operation and/or small residual VSDs were associated with a poor hemodynamic outcome. In neither group could significant correlations be observed between hemodynamic aberrations, shunt size, and/or age. Among patients who underwent surgery, the earlier surgical trauma might have contributed to the functional aberrations, but in group 2 the only likely explanation for the findings seems to be the VSD itself. Possibly a long-standing VSD--found unnecessary to repair according to commonly accepted criteria--may lead to disturbed systolic function and increase in compliance of both ventricles via a chronic pressure and volume overload.

Vascular structure in lung tissue obtained at biopsy correlated with pulmonary hemodynamic findings after repair of congenital heart defects

At the time of surgical repair, a lung biopsy was performed on patients with congenital heart defects who either had pulmonary hypertension or in whom it would be likely to develop if the lesion were not corrected. Pulmonary vascular changes, assessed morphometrically and also according to the classification of Heath and Edwards (Circulation 18: 533, 1958), were correlated with the postoperative pulmonary hemodynamic findings: mean pulmonary arterial pressure the day after correction and mean pulmonary arterial pressure and pulmonary vascular resistance measured 1 year later. On the first postoperative day, increased mean pulmonary arterial pressure was uncommon in patients with morphometric grade A or B (mild) biopsy findings and Heath-Edwards grade N (normal), and if it was present it was of a mild degree. Mean pulmonary arterial pressure was commonly elevated in those with grade B (severe) or C (mild or severe) and Heath-Edwards grade I biopsy results and was more frequently elevated in those with grade II findings. Moderate-to-severe elevation of mean pulmonary arterial pressure was invariable in patients with Heath-Edwards grade III changes regardless of the morphometric grade. One year after repair, mean pulmonary arterial pressure and/or pulmonary vascular resistance were normal in all patients whose conditions were corrected surgically before 9 months of age regardless of the severity of the pulmonary vascular changes. Values were normal in patients whose conditions were repaired surgically at 9 months of age or later who had grade A or B (mild) morphometric findings with any Heath-Edwards grade or grade B (severe) morphometric findings with Heath-Edwards grade I but were increased in half of the patients with grade B (severe) morphometric findings and Heath-Edwards grade II or with grade C (mild or severe) and Heath-Edwards grade I or II changes. Pulmonary arterial pressure and pulmonary vascular resistance were increased in all patients whose conditions were repaired after 2 years of age with grade C morphometric findings and to a severe degree if associated with Heath-Edwards grade III. Thus, although the Heath-Edwards grade can usually be used to identify patients at risk for pulmonary hypertension in the early postoperative period, both the morphometric and the Heath-Edwards grades as well as the age of the patient at the time of repair can be used to determine whether pulmonary arterial pressure and resistance eventually return to normal or remain elevated.

Exercise induced pulmonary vasoconstriction

Pulmonary vascular resistance normally falls or remains unchanged during exercise. Seven children with pulmonary hypertension were exercised during cardiac catheterisation after operative correction of ventricular septal defect (6) and truncus arteriosus (1). Except for the presence of moderate pulmonary hypertension, resting haemodynamics in these seven children were similar to those of normal children of equal age, but during exercise the postoperative patients showed a rise rather than a fall (+2% vs -18%) in total pulmonary vascular resistance. Two of the seven children had a substantial increase in pulmonary arteriolar resistance during exercise (from 509 to 715 dyne s cm-5 in one patient and from 606 to 828 dyne s cm-5 in the other). These two patients did not differ from normal children in respect of arterial or mixed venous oxygen saturations or of pH with exercise, nor was left atrial pressure related to the rise in pulmonary resistance. These two patients, however, had only a small rise in cardiac output during exercise (6.8% and 43.1%) in spite of a substantial increase in oxygen consumption (121% and 373%). One of the patients with exercise-induced pulmonary vasoconstriction had an 82% increase in resting pulmonary vascular resistance over a five year period subsequent to her first exercise study. Analysis of these data, and those previously reported, suggests that exercise induced pulmonary vasoconstriction may occur in 10 to 25% of patients who survive correction of certain congenital cardiac defects. The vasoconstriction cannot be attributed to abnormal changes in blood gases or left atrial pressure, and may be an early sign of progressive pulmonary hypertension.

Results of surgical treatment of ventricular septal defects with pulmonary hypertension

Two hundred and twenty-five consecutive patients with interventricular septal defect and associated pulmonary hypertension have undergone corrective surgery at the Christian Medical College Hospital. The mean preoperative systolic pulmonary artery pressure was 70.5 (range 31-136) mm Hg and the calculated pulmonary vascular resistance ranged from 300 to 1680 dyn/s cm-5. A paracoronary right ventriculotomy was the approach of choice. Profound hypothermia and circulatory arrest were not used, even in 12 patients weighing under 10 kg. Among the older children and young adolescents there were 27 who had a calculated pulmonary vascular resistance of over 800 dyn/s cm-1 and their mortality was 22%, which is good when compared with that of other series. It is evident that both the early and the late death rate after surgery increase with the age of the patient, especially in those with associated pulmonary hypertension. In 69 patients studied after repair recatheterisation showed no residual defect by oximetry. The fall in the pulmonary artery pressures after surgery has been striking in most patients. The late death rate was 2.5%. The surviving patients are leading normal, active lives.

Rest and exercise ventricular function in adults with congenital ventricular septal defects

Rest and exercise right and left ventricular function were compared using equilibrium gated radionuclide angiography in 19 normal sedentary control subjects (mean age 28 years, range 22 to 34) and 34 patients with hemodynamically documented congenital ventricular septal defect (VSD) (mean age 27 years, range 20 to 40). The 34 patients with VSD were divided into 3 groups: those in Group 1 (17 patients) had pulmonary to systemic blood flow ratios of less than 2 to 1; those in Group 2 (12 patients) had prior surgical closure of VSD (mean interval from surgery 17 years, range 9 to 22), and those in Group 3 (5 patients) had Eisenmenger's complex. Gated radionuclide angiography was performed at rest and during each level of graded supine bicycle exercise to fatigue. Heart rate, blood pressure, maximal work load achieved, and right and left ventricular ejection fractions were assessed. The control subjects demonstrated an increase in both the left and right ventricular ejection fractions with exercise (0.70 +/- 0.07 to 0.79 +/- 0.05 and 0.46 +/- 0.06 to 0.57 +/- 0.04; p less than 0.001 for left and right ventricles, respectively). All study groups failed to demonstrate an increase in ejection fraction in either ventricle with exercise. Furthermore, resting left ventricular ejection fraction in Groups 2 and 3 was lower than that in the control subjects (0.59 +/- 0.09 and 0.54 +/- 0.06 versus 0.70 +/- 0.07; p less than 0.001) and resting right ventricular ejection fraction was lower in Group 3 versus control subjects (0.30 +/- 0.07 versus 0.46 +/- 0.06; p less than 0.001). Thus (1) left and right ventricular function on exercise were abnormal in patients with residual VSD as compared with control subjects; (2) rest and exercise left ventricular ejection fractions remained abnormal despite surgical closure of VSD in the remote past; (3) resting left and right ventricular function was abnormal in patients with Eisenmenger's complex; (4) lifelong volume overload may be detrimental to myocardial function.

Conduction defects, ventricular arrhythmias, and late death after surgical closure of ventricular septal defect

One hundred and eighty-seven patients who had surgical closure of a ventricular septal defect between 1958 and 1975 were followed for up to 21 years. there were 17 late sudden deaths of which eight occurred in completely fit patients while nine were already under medical care. In an attempt to elucidate possible risk factors and reoperative and serial postoperative electrocardiograms of all patients were studied. Fifty-one unselected healthy follow-up patients agreed to 24 hour ambulatory monitoring. Progressive exercise testing (Bruce protocol) was carried out on 31 of them and an additional seven patients. There was a significant correlation between recorded ventricular arrhythmias and conduction defects, particularly progressive conduction defects. Transient complete heart block carried a bad prognosis and grade 3-4b ventricular arrhythmias were a major risk factor and recorded in 10 of the 17 patients who died. Long-term postoperative electrocardiographic follow-up is recommended and 24 hour ambulatory monitoring and exercise testing complement the findings of the resting electrocardiogram. The long-term treatment of survivors found to have ventricular arrhythmias must be considered.

Pulmonary hypertension accompanying ventricular septal defect and patent ductus arteriosus. Management in infancy and early childhood

Forty-one infants and children with the combination of patent ductus arteriosus (PDA) and ventricular septal defect (VSD) were encountered over 20 years. Twenty-four presented in infancy with congestive cardiac failure. Pulmonary hypertension was present in 32, the cause in 19 being increased pulmonary blood flow. Increased pulmonary vascular resistance (PVR) was detected in 13 (indicated by a pulmonary to systemic resistance ratio (Rp : RS) greater than 0.24:1 and PVR greater than 4 units). Thus 22% had a pulmonary artery systolic pressure less than 30 mmHg and 68% had a pulmonary vascular resistance below four units, indicating an unusually mild form of the combined condition in these patients. Surgical management is discussed, and in particular the question of simultaneous closure of the defects during infancy. Cardiac failure, resistant to drug treatment, and increased PVR are indications of operation. The PDA should be closed and only if there is no substantial fall in pulmonary artery pressure is the VSD repaired.

Ventilatory function in the Eisenmenger syndrome

Ventilatory function and carbon monoxide transfer factor were studied in nine adult patients with post-tricuspid intracardiac defects and the Eisenmenger syndrome. A consistent mild defect of ventilatory function was found, with raised residual volume and closing capacity and reduction of other lung volumes and maximal expiratory flows. Maximal expiratory flow was particularly reduced at low lung volumes. One of the four subjects in whom pressure-volume studies were performed showed loss of normal elastic recoil at low lung volumes. A significant poorly ventilated space was excluded since the volume of distribution of helium during a 10 second breath-hold at full inspiration was close to plethysmographically measured total lung capacity. Carbon monoxide transfer factor, after correction for haemoglobin concentration, was 77% of predicted normal values. Sequential assessment of carbon monoxide transfer factor might be useful in the early diagnosis of pulmonary vascular disease in infants with large intracardiac defects, since it is likely to be raised early due to high pulmonary blood flow and will fall with the development of pulmonary vascular disease.