Transcatheter patent ductus arteriosus occlusion: evolution of techniques and results from the 1990s

OBJECTIVE

To review the evolution of transcatheter patent ductus arteriosus (PDA) occlusion techniques and results.

METHODS

A single institution, retrospective review including all patients with intention to close a PDA from 1991 to 1998, with no exclusions.

RESULTS

Rashkind occluder (n = 65), sideris double-button (n = 6), Cook detachable coil (n = 28) and Amplatzer ductal occluder (n = 4) were used. Successful implantation occurred in 99 of 103 patients. There was a need for a second transcatheter procedure to close residual ductal shunting in 12% of patients: Rashkind umbrellas (n = 8), double-button (n = 1), coils (n = 3). Eight patients (8%) required surgery, including 4 of 6 patients with the double-button occluder.

CONCLUSIONS

The Rashkind occluder and the Sideris double-button device both had an unacceptably high rate of residual shunts requiring a second transcatheter procedure or surgical closure. Detachable coils and the Amplatzer ductal occluder have become the current technology of choice for transcatheter PDA closure with high success rates.

Cardiac output measurements in congenital heart disease: validation of a simple, portable Doppler method

Noninvasive Doppler cardiac output measurements are clinical standards in adults and children. Presently, these standard Doppler methods generally require relatively expensive and large imaging equipment with complex signal-processing techniques. Thus, universal access to these important measurements has been limited. Simple, portable Doppler methods have been validated previously and applied to infants and children without cardiac disease. Nevertheless, these specific, inexpensive techniques have not been validated in children with complex congenital heart disease. Accordingly, we compared a noninvasive, suprasternal, non-image-guided, pulsed Doppler cardiac output with standard invasive Fick cardiac outputs in 20 patients (age range, 1 month to 15 years) with congenital heart disease. Doppler cardiac output was displayed by multiplying the mean velocity with an operator-selected angiographic or echographic estimate of the aortic diameter. The values from linear regression analysis were r = 0.96; Doppler cardiac output = 0.98 x Fick cardiac output - 0.08 L/min (range, 0.55-3.10 L/min). The 95% confidence limits were less than 35% of the mean of Doppler and Fick cardiac outputs across the range of measurements. We conclude that relatively linear and accurate measurements of cardiac output can be made by this simple, inexpensive, portable method in selected infants and children with various forms of congenital heart disease.

Intravenous immunoglobulin in acute rheumatic fever: a randomized controlled trial

BACKGROUND

Acute rheumatic fever (ARF) remains the leading cause of acquired heart disease in children worldwide. No therapeutic agent has been shown to alter the clinical outcome of the acute illness. Immunological mechanisms appear to be involved in the pathogenesis of ARF. Intravenous immunoglobulin (IVIG), a proven immunomodulator, may benefit cardiac conditions of an autoimmune nature. We investigated whether IVIG modified the natural history of ARF by reducing the extent and severity of carditis.

METHODS AND RESULTS

This prospective, double-blind, randomized, placebo-controlled trial evaluated IVIG in patients with a first episode of rheumatic fever, stratifying patients by the presence and severity of carditis before randomization. Patients were randomly allocated to receive 1 g/kg IVIG on days 1 and 2 and 0.4 g/kg on days 14 and 28, or they received a placebo infusion. Clinical, laboratory, and echocardiographic evaluation was performed at 0, 2, 4, 6, 26, and 52 weeks. Fifty-nine patients were treated, of whom 39 had carditis (including 4 subclinical) and/or migratory polyarthritis (n=39). There was no difference between groups in the rate of normalization of the erythrocyte sedimentation rate or acute-phase proteins at the 6-week follow-up. On echocardiography, 59% in the IVIG group and 69% in the placebo group had carditis at baseline. There was no significant difference in the cardiac outcome, including the proportion of valves involved, or in the severity of valvar regurgitation at 1 year. At 1 year, 41% of the IVIG and 50% of the placebo group had carditis.

CONCLUSIONS

IVIG did not alter the natural history of ARF, with no detectable difference in the clinical, laboratory, or echocardiographic parameters of the disease process during the subsequent 12 months.

Left ventricular mechanics during and after acute rheumatic fever: contractile dysfunction is closely related to valve regurgitation

OBJECTIVES

The purpose of this study was to characterize left ventricular (LV) mechanics during acute rheumatic fever (ARF) and to define factors influencing remodeling after the acute event.

BACKGROUND

Acute rheumatic fever is associated with varying degrees of valvulitis and myocarditis, but the impact of these factors on LV mechanics is poorly defined.

METHODS

Echocardiograms and clinical data were reviewed in 55 patients aged 11.2 +/- 2.6 years during ARF. Valve regurgitation was absent or mild in 33 (group I) and moderate or severe in 22 (group II). Forty-two children (75%) underwent a further examination after ARF.

RESULTS

Group I patients demonstrated a mildly elevated LV size during ARF and had normal indexes at follow-up. Group II patients demonstrated a markedly elevated LV size (end-diastolic dimension z-score 3.6 +/- 1.8, p < 0.01 compared with the normal population) and decreased shortening fraction (z-score -0.8 +/- 1.4, p < 0.05). The stress-velocity index, a z-score describing the velocity of shortening-afterload relationship, was normal in group II patients with mitral regurgitation (-0.2 +/- 1.2, p = NS) but was depressed in those with aortic regurgitation or both (- 1.4 +/- 1.4, p < 0.01). At follow-up the stress-velocity index remained depressed (-1.2 +/- 1.0, p < 0.01) and had deteriorated in those treated nonsurgically compared with those treated surgically (interval change nonsurgical -0.7 +/- 1.2 vs. surgical 1.3 +/- 1.3, p = 0.005).

CONCLUSIONS

The evolution of contractile dysfunction during and after ARF is dependent on the degree and type of valve regurgitation and may be influenced by surgical intervention. These findings suggest that mechanical factors are the most important contributors to myocardial damage during and after ARF.

Subclinical aortic perforation with the infant double-button patent ductus arteriosus occluder

Modification of the double-button (Sideris) patent ductus arteriosus (PDA) occluder has resulted in a single-strut aortic component rather than the conventional cross-strut design. We report the use of this infant PDA occluder for transcatheter closure in three patients with PDA measuring 2 mm, 3.7 mm, and 4 mm. Subclinical aortic perforation with a small aortic aneurysm developed in two patients 1 year after occluder implantation. The third patient had developed a small aortic aneurysm without perforation at 3-month follow-up. All three patients had a residual shunt and underwent successful PDA surgical closure with aortic aneurysmal repair. Single-strut umbrella designs are not recommended for PDA transcatheter closure.

Prevention of infective endocarditis associated with dental treatment and other medical interventions. National Heart Foundation

The prevention of infective endocarditis is extremely important for people with valvular heart disease and other high-risk cardiac conditions. The following is the National Heart Foundation's updated recommendations for the prophylaxis of infective endocarditis. The recommended antibiotic regimens have changed considerably from the previous guidelines. In response to these guidelines, Pharmac has instituted a number of changes to the Schedule to reduce the barriers to prescribing the recommended drugs for this indication. Pharmac expects that the last of these drugs to be listed on the Schedule (cefuroxime axetil) will be in place by 1 October 1999. Prescriptions will need to be endorsed "prophylaxis for endocarditis". Therefore, any prescriber (doctor or dentist) will be able to prescribe the recommended drugs on an endorsed prescription but, until 1 October 1999, some of the drugs may not be fully subsidised. Pharmac will be informing prescribers of the details of these changes in the near future. The Ministry of Health has recently alerted practitioners to the possible risk of heart valve damage following the long-term use of weight-loss drugs fenfluramine (Ponderax) and dexfenfluramine (Adifax). All patients who have taken these drugs for longer than 3 months should have a clinical check and, if any abnormality is detected, should be referred to a cardiologist. If mild or greater aortic or mitral regurgitation is present, antibiotic prophylaxis against endocarditis is recommended.--Boyd A Swinburn, Medical Director, National Heart Foundation.

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.

Failure of implementation of the National Heart Foundation of New Zealand guidelines for the management of dyslipidaemia

AIMS

We examined the outcome of patients at high absolute risk of coronary events who had been discharged from the Green Lane Hospital risk factor clinic before publication of the 1993 National Heart Foundation of New Zealand (NHF) guidelines for management of dyslipidaemia.

METHODS

Consecutive patients who had been discharged >12 months previously were followed up by general practitioner and patient questionnaires. Patients were categorised according to risk of a coronary event over 10 years. Ideal lipid levels (cholesterol <5.2 mmol/L, high-density lipoprotein (HDL) cholesterol >1 mmol/L, total:HDL cholesterol ratio <5) and 'acceptable' lipid levels (cholesterol <6.5 mmol/L for high risk, <7.5 for moderate risk, <8 in men and <8.5 in women at mild or low risk) were defined according to the NHF guidelines.

RESULTS

Of the 270 patients, 55.6% were at very high risk, 25.5% at high risk, 10.4% at moderate risk, 3.8% at mild risk and 0.7% at low risk. Twenty-four percent of patients were managed on diet alone at clinic discharge and 18% at follow up of 32+/-12 months. Total cholesterol (6.39 mmol/L), HDL cholesterol (1.22 mmol/L) and the total:HDL cholesterol ratio (5.71) were unchanged from discharge. In the very high risk group ideal lipid levels were achieved in only 12% at discharge and 7% at follow up. The corresponding figures for achievement of acceptable lipids at discharge compared with follow up were 48% and 39% for the high risk group, 88% and 79% for the moderate risk group and 93% and 93% for the mild risk group. The corresponding figures for achievement of ideal lipids were 4% and 8% for the high risk group, 0% and 5% for the moderate risk group and 7% and 7% for the mild risk group.

CONCLUSIONS

Lipid levels achieved during clinic visits were maintained long term, but there were no improvements following publication of the NHF guidelines. Continued efforts are needed to increase awareness and implementation of the guidelines, particularly in patients at high risk. Removal of the restrictions on prescription of lipid modifying agents by general practitioners and improved interchange between general practitioners and specialists should greatly improve these outcomes.

Transthoracic echocardiography for right ventricular function late after the Mustard operation

The aim of the study was to assess echocardiographic measurements of right ventricular function in 24 patients aged 10.7 to 28.9 years (mean 18.9 years) receiving the Mustard baffle repair for transposition of the great arteries. Right ventricular ejection fraction (RVEF) from single-plane areas and area length volumes, pulsed Doppler mean aortic acceleration, and tricuspid annular plane systolic excursion were correlated with first-pass radionuclide RVEF. The mean radionuclide RVEF was 39%, the mean echocardiographic apical four-chamber RVEF was 41%, and the mean short-axis RVEF was 37%. Echocardiographic apical four-chamber right ventricular end-diastolic volumes were 102 +/- 24 ml/m2, and RVEF interobserver and intraobserver correlation coefficients were 0.73 and 0.81, respectively. Radionuclide and echocardiographic RVEF correlation coefficients were short axis, 0.40; apical four-chamber, 0.24; average four-chamber and short axis, 0.38; mean aortic acceleration, 0.26; and tricuspid annular plane systolic excursion, 0.06. The range of echocardiographic right ventricular volumes for young adults receiving the Mustard repair is established allowing serial observation of dilatation. However, simple and reliable echocardiographic prediction of RVEF remains elusive in this age group.

Echocardiographic diagnosis of subclinical carditis in acute rheumatic fever

The diagnosis of carditis in acute rheumatic fever traditionally depends on characteristic auscultatory findings. The advent of pulsed and colour Doppler echocardiography provides a method of detecting minor degrees of pathological regurgitation without characteristic clinical signs. Using strict criteria, pathological left heart regurgitation can be differentiated from physiological regurgitation: colour Doppler must show a substantial colour jet in two planes extending well beyond the valve leaflets; pulsed Doppler must confirm a high velocity signal, holosystolic for mitral regurgitation, or holodiastolic for aortic regurgitation. Several centres have observed subclinical carditis in children with acute rheumatic fever. We are confident that we are not overdiagnosing valvulitis, having tested this in a blinded fashion. Subclinical valvulitis should be accepted as evidence of carditis, a major diagnostic criterion for acute rheumatic fever.

Outcome of pregnancy after the Mustard operation for transposition of the great arteries with intact ventricular septum

OBJECTIVES

This study examined the outcome of pregnancy in patients with transposition of the great arteries and an intact ventricular septum after a Mustard operation.

BACKGROUND

Before the introduction of surgical treatment, most children with transposition of the great arteries died in early infancy. A number of these patients have now reached their reproductive years. There is little information about the effect of pregnancy on cardiovascular status, particularly the ability of the right ventricle to adjust to the hemodynamic changes of pregnancy. The outcome for the offspring and their risk of congenital heart disease are also unknown.

METHODS

Twenty-three female late survivors after the Mustard operation > 15 years of age were reviewed in relation to the occurrence of pregnancy and its outcome. Serial echocardiographic estimates of right ventricular volume during pregnancy were made in three local patients.

RESULTS

Nine women had 15 pregnancies. They were asymptomatic before pregnancy and remained free from cardiac symptoms during each pregnancy. Right ventricular volume in the three patients studied increased during pregnancy but returned to normal at 8 to 11 weeks postpartum. There were 12 live births, 2 spontaneous abortions and 1 intrauterine death. None of the liveborn infants had evidence of congenital heart disease.

CONCLUSIONS

In this small group of women with good quality late survival after a Mustard operation, pregnancy was well tolerated. We suspect that the incidence of congenital heart disease in infants of mothers with transposition of the great arteries will be at the lower end of the range for mothers with different types of congenital heart disease, but further data will be needed to confirm this.

Waiting lists for coronary artery surgery: can they be better organised?

AIM

To determine whether a numerical ranking system can provide an equitable basis for prioritising patients awaiting coronary artery bypass grafting.

METHODS

A review of the current coronary surgery waiting list was undertaken using a newly developed scoring system. The factors included in the score were age, symptoms, results of exercise testing, coronary anatomy, employment status and perceived surgical risk. This score was compared with a Canadian consensus system. Rankings were then compared with the clinical priorities given by clinicians when the patients were placed on the waiting list.

RESULTS

There was excellent correlation between the two priority ranking systems using only those items included in the Canadian system (r = 0.9179). However, correlation between the Canadian system and the full Green Lane Hospital (GLH) scoring system was weaker (r = 0.6869). The Canadian system assigned higher surgical priorities than Auckland clinicians. Comparison between the GLH system and clinical priority gradings (O, urgent out of hospital), (A) and (B) showed considerable scatter. Waiting times for these three categories considered acceptable by the Canadian consensus group were two to six weeks for priority (O), six weeks to three months for priority (A) and three to six months for priority (B). The mean times on the waiting list for the 260 patients still awaiting surgery at GLH were two months for (O), 11 months for (A) and 22 months for (B).

CONCLUSIONS

The Canadian and expanded GLH ranking systems are no more than aids to establishing priorities. They cannot replace clinical judgement because the importance of individual scoring items is heavily influenced by the ranking of other items. Waiting times for surgery are now grossly excessive despite the use of criteria for entry to the waiting list which are very conservative by international standards. There is no equitable or clinically acceptable way to modify priorities to reduce waiting times, and institution of a booking system is impractical.

Efficacy and dosage of enalapril in congenital and acquired heart disease

In a tertiary referral centre 63 patients underwent 67 treatment periods with enalapril. The median age was 5.4 months. All children had signs of heart failure: congestive cardiac failure with breathlessness at rest was present in 88%. Haemodynamic groups were left-to-right shunt (n = 15), impaired ventricular function (n = 14), after cardiac surgery (n = 23), valvar regurgitation (n = 12), and hypertension (n = 3). Serial clinical, radiological, and laboratory data were used to judge outcome. The mean (SD) maximal dose was 0.30 (0.21) mg/kg/day. Thirty nine (58%) patients improved, 20 (30%) showed no improvement, and eight (12%) had side effects requiring discontinuation of enalapril. Renal failure in eight patients was related to young age, low weight, and left-to-right shunt group. Three patients died in congestive heart failure with renal failure. Enalapril was clinically safe and effective for children with cardiac failure secondary to ventricular impairment, valvar regurgitation, or after cardiac surgery. Renal failure was a problem in young infants with left-to-right shunts.

Adult congenital heart disease: principles and management guidelines: Part II

The treatment of congenital heart disease may be palliative because many residua and sequelae persist into adulthood. Except for trivial lesions and anomalies such as PDA or secundum ASD where surgical cure is possible, continued supervision is mandatory. These patients deserve expert medical assessment from adult cardiologists and from other specialists when appropriate. The prevalence of postoperative adult congenital heart disease is increasing: by the year 2000 it is estimated that over 2000 in each million of the adult population will have congenital heart disease, one third of these having undergone cardiac surgery. It is important that some adult cardiologists in each major centre develop skills in adult congenital heart disease for this new patient population.

Transcatheter closure of patent ductus arteriosus in children and adults

AIM

To describe the initial New Zealand experience of transcatheter patent ductus arteriosus closure in adults and children.

METHODS

Twenty-three children beyond infancy and four adults with isolated patent ductus arteriosus were selected for transcatheter umbrella closure. Rashkind umbrellas were placed across the patent ductus arteriosus through a percutaneously inserted long venous sheath using the Mullins technique.

RESULTS

In 25 of the 27 patients a Rashkind umbrella was placed accurately. In two patients the umbrella could not be placed accurately: in one the procedure was abandoned uneventfully and in one the umbrella embolised to the right pulmonary artery necessitating surgical removal of the device and patent ductus arteriosus closure. There were no other significant complications. A second umbrella insertion is planned in two children for a significant residual leak at 1-year follow up.

CONCLUSIONS

Transcatheter patent ductus arteriosus closure is a low risk and usually effective alternative to surgical closure for the majority of patients beyond infancy.

Percutaneous balloon angioplasty for early postoperative modified Blalock-Taussig shunt failure

Percutaneous balloon angioplasty was successful initial treatment for 2 infants who, early after operation, developed obstruction at the proximal anastomotic site of a modified Blalock-Taussig shunt. Two years later the first child had not required reoperation and the dilatation site was patent angiographically. The other baby progressed well after angioplasty but because of surgical concern about the long-term success of angioplasty, shunt surgery was repeated, the baby dying after reoperation. Angioplasty of proximal obstruction in these shunts is feasible and satisfactory long-term palliation can be achieved avoiding repeat shunt surgery before the more definitive Fontan-type procedure.

The role of dipyridamole in addition to low dose aspirin in the prevention of occlusion of coronary artery bypass grafts

One hundred and one subjects were randomised to receive either aspirin 100 mg or aspirin 100 mg + dipyridamole 300 mg daily before undergoing coronary bypass surgery. The drugs were commenced at least 36 hours before operation and patients were followed for one year. There were three perioperative deaths and 37 withdrawals, of which 14 were drug related (aspirin four, aspirin + dipyridamole ten). Cineangiocardiograms at nine weeks and one year showed vein graft patency rates of 93% and 87% for subjects treated with aspirin alone; and 90% and 89% in those who received aspirin+dipyridamole. During the follow-up period 14% of 232 coronary lesions in the aspirin treated group advanced by more than two grades compared with 15% of 315 lesions in the aspirin+dipyridamole group. The study did not establish superiority of one regimen over another in terms of graft patency or progress of lesions in native vessels. However, low dose aspirin was better tolerated than combination therapy.

The addition of oatbran to a low fat diet has no effect on lipid values in hypercholesterolaemic subjects

AIMS

to assess the hypocholesterolaemic effect of adding 50 g of oatbran to the diet of hypercholesterolaemic subjects already prescribed a diet with less than 30% of energy from fat.

METHODS

twenty-nine volunteers aged 21-67 years with total serum cholesterol levels 5.59-8.5 mmol/L prescribed a diet containing less than 30% of energy intake as fat, and with a body mass index between 19.8 and 29.3, were enrolled in a crossover study to assess the effect of the addition to the diet of 50 g daily of oatbran. After six weeks of an oat-free control diet, subjects were randomised to eat 50 g daily of oatbran or to continue on the oat-free diet. Six weeks later the subjects crossed to the alternative diet for a further six week period. Lipid levels were assessed in weeks five and six of each study period.

RESULTS

twenty-four subjects completed the study consuming 51.7 (SD 15.5) g of oatbran daily during the treatment phase. No significant difference was seen between the oatbran and control diet periods in body mass index, energy or fat intake, or in total cholesterol, LDL and HDL fractions, apolipoprotein A1 and B levels, or triglyceride levels. Considerable variation was observed between the paired lipid results.

CONCLUSIONS

ingestion of 50 g of oatbran daily by hypercholesterolaemic subjects on a low fat diet showed no influence on serum lipid levels. The importance of using at least duplicate samples in assessing changes in lipid values is emphasised.

Acute hemodynamic effects of converting enzyme inhibition in children with intracardiac shunts

The short-term hemodynamic effects of intravenous enalaprilat were assessed in 26 infants and children, aged 6 months to 15 years, with intracardiac shunts undergoing cardiac catheterization. Pulmonary and systemic pressure, flow, and resistance indices were measured by the direct Fick method before and 30 min after enalaprilat at 0.06 mg/kg. Aortic and pulmonary artery pressure decreased 15 and 20%, respectively, by 10 min, with little further change at 30 min. The heart rate did not change significantly and there was no reduction in systemic flow. In those with a large ventricular septal defect and normal or near-normal pulmonary resistance (less than 3.5 u.m2, n = 8), the mean pulmonary-systemic flow ratio decreased from 2.9 +/- 0.3 to 2.4 +/- 0.3 (p less than 0.05) and the mean left-to-right shunt from 7.4 +/- 0.8 to 5.9 +/- 0.7 L/min/m2 (p less than 0.02). Those with an elevated pulmonary vascular resistance (greater than 5 u.m2, n = 8) showed a varied response. Two children, both with Down's syndrome, an atrioventricular canal defect, and reversible pulmonary hypertension (as assessed by an infusion of isoproterenol), had no decrease in pulmonary vascular resistance with enalaprilat. There were no adverse effects. Converting enzyme inhibitors may benefit "heart failure" associated with large ventricular septal defects and normal or mildly elevated pulmonary resistance.

Stenosis of pulmonary veins in Down syndrome

Two patients with Down syndrome, intracardiac communications and elevated pulmonary arteriolar resistance presented early in life. Both patients had significant stenosis of pulmonary veins. The progressive nature of the stenosis is illustrated in one patient. Pulmonary venous stenosis in Down syndrome has been recorded only twice before in the literature, and may play a part in the early onset of pulmonary vascular occlusive disease in some patients.

Predictors of long-term survival with Ebstein's anomaly of the tricuspid valve

In patients with Ebstein's anomaly of the tricuspid valve, predictors of death and indications for surgery are poorly defined. We retrospectively reviewed 48 patients with Ebstein's anomaly, 17 (35%) of whom presented in the first week of life. Duration of follow-up extended to 32 years (greater than 10 years in 35%). Twenty of the 48 patients (42%) died, 6 in the first week of life and 1 at age 5 months. Thirteen of the 41 patients surviving to age 6 months subsequently died, 50% probability of survival being reached at 47 years. Significant (p less than or equal to 0.05) predictors of death in this group were: male sex, cardiothoracic ratio greater than or equal to 0.65, New York Heart Association class III or IV, breathlessness and the absence of Wolff-Parkinson-White syndrome. Eight patients died suddenly. A cardiothoracic ratio greater than or equal to 0.65 was a better predictor of sudden death than functional status. All who developed atrial fibrillation died within 5 years. Other atrial arrhythmias were not helpful in predicting sudden death. In view of these findings, tricuspid valve surgery is recommended before the cardiothoracic ratio reaches 0.65, regardless of the symptomatic state.

Effects of prostaglandin E1 given in low doses on the histopathology of the arterial duct

The histopathology of the arterial duct was studied in relation to the maximal infusion rate of prostaglandin E1 administered in 35 infants with congenital heart disease. Two groups were distinguished based on the maximal infusion rate. The group receiving prostaglandin at low dose received 0.01 to 0.05 micrograms/kg/min (16 cases), the group having a high dose received greater than 0.05 to 0.7 micrograms/kg/min (19 cases). The histopathology was compared between the groups. Ductal damage was less common in the cases receiving a low rate of infusion than in those having a high rate of infusion. Multivariate analysis showed no relation between ductal pathology and the age of onset or duration of treatment, nor on the total dose of prostaglandin E1. Histological abnormalities were more common in patients with a gestational age equal to or greater than 40 weeks. Ductal damage was less common in patients with pulmonary atresia or stenosis compared with other anatomic diagnoses. Low dose infusions are recommended for treatment with prostaglandin E1 in infants with congenital heart disease.

Progress of patients with pulmonary atresia after systemic to pulmonary arterial shunts

Between February 1980 and June 1987, 42 shunts were placed in 39 infants with pulmonary atresia: 33 were modified Blalock-Taussig shunts with polytetrafluoroethylene (PTFE) and 9 were classic Blalock-Taussig shunts. There were four hospital deaths not related to the shunts. The remaining 35 patients were followed up for 1.6 months to 6.3 years (mean, 24.7 +/- 18 months). Repeat cineangiocardiographic studies revealed stenosis or distortion of the pulmonary arteries related to the site of the shunt in 11/22 patients (50%) with PTFE shunts and in 1/6 (17%) with classic Blalock-Taussig shunts; the stenosis was severe in only 1 patient. Mean increase in the pulmonary arterial index in the group with classic Blalock-Taussig shunts was 117 +/- 52 mm2/m2 (not significant) and in the group with PTFE shunts, 158 +/- 21 mm2/m2 (p less than 0.001). Late shunt occlusion occurred in 1 patient 23 months postoperatively. Thereafter, shunt patency rate remained at 94% +/- 6%. At the end of 1 year 81% +/- 7% of patients were judged to have adequate palliation, but between 2 and 3 years, only 60% +/- 10%. Univariate analysis showed that after 2 years the ranking order for successful palliation was classic Blalock-Taussig, 5-mm PTFE, and 4-mm PTFE shunts, but differences did not achieve statistical significance.

Kawasaki disease in Auckland, 1979-1988

Records of 34 children diagnosed as having Kawasaki disease in the Auckland region from 1979 to 1988 inclusive were reviewed. Diagnostic and associated features were similar to those reported from North America and Japan. The incidence (average 5.1 per year per 100,000 less than 5 years of age) was similar to that reported in Europe and North America amongst nonorientals and was similar in Polynesians and nonPolynesians. Coronary artery abnormalities were found in five cases (15%), and two cases, both of whom presented before five months of age, died. Those with abnormal coronary arteries had fever for a significantly longer period than those with normal coronary arteries.

Rest and exercise hemodynamics of 20 to 23 mm allograft, Medtronic Intact (porcine), and St. Jude Medical valves in the aortic position

Doppler echocardiography was used to measure gradients and valve areas at rest and after supine bicycle exercise in 35 patients with valve replacements 20 to 23 mm in size. Thirteen patients with a St. Jude Medical valve (St. Jude Medical, Inc., St. Paul, Minn.) were matched to 13 patients with an allograft valve, and seven patients with a Medtronic Intact (porcine) valve (Medtronic, Inc., Minneapolis, Minn.) to seven patients with an allograft valve. Patients were matched for age, sex, valve size, body surface area, and left ventricular systolic function. There was no statistically significant difference between the matched groups for body surface areas, resting cardiac output, exercise heart rate, or workload achieved. Mean pressure gradient was higher for St. Jude Medical than for allograft groups, both at rest (11.8 +/- 6.67 mm Hg for St. Jude Medical versus 6.67 +/- 2.98 mm Hg for allografts) and after exercise (16.4 +/- 8.47 mm Hg versus 9.7 +/- 3.94 mm Hg), but the differences were of borderline significance (p = 0.016 and 0.027, respectively). Valve area at rest was similar for both devices (1.4 +/- 0.45 cm2 for St. Jude Medical versus 1.8 +/- 0.56 cm2 for allograft; p greater than 0.1). There were highly significant differences between patients with Intact and those with allograft valves for resting mean pressure gradient (19.3 +/- 4.23 mm Hg for Intact versus 5.9 +/- 3.68 mm Hg for allograft; p less than 0.001) and for exercise mean pressure gradient (27.8 +/- 8.63 mm Hg versus 8.1 +/- 8.43 mm Hg; p less than 0.001). The differences between the valve areas at rest also were significant (1.1 +/- 0.12 cm2 versus 2.2 +/- 0.62 cm2; p less than 0.01). It is concluded that when a tissue valve is indicated in patients with a small aortic root, the freehand allograft aortic valve is an ideal device from the hemodynamic perspective and is superior to the Intact valve. It is also probably superior in this respect to the St. Jude Medical valve, although the analysis may be biased slightly in favor of the allograft valve.

Early follow-up of patients with the Medtronic Intact porcine valve. A new cardiac bioprosthesis

A new-generation porcine valve fixed in glutaraldehyde at zero pressure and mounted on an acetal copolymer flexible stent was inserted in 97 patients between August 1983 and October 1986. The mean age of the patients was 51 years (range 10 to 76) and eight were under the age of 20 years. There were 57 mitral, 33 aortic, and 10 tricuspid valve replacements. Concomitant coronary artery bypass grafting was performed in 9% of patients, 40% underwent multiple valve operations, and in 40% the procedure was a reoperation. Mean follow-up was 26 months (range 12 to 49) and was 99% complete. There were no examples of primary tissue failure, and only to reoperations have been undertaken for infective endocarditis alone. The early mortality rate was 8.2% and the late mortality rate, 12.1%. Four late deaths were valve related (two caused by infective endocarditis and two by embolism). The actuarial 3-year survival rate was 70%, freedom from infective endocarditis 879%, freedom from embolism 87%, freedom from reoperation 90%, and freedom from valve-related complications 77%. All but three surviving patients were in New York Heart Association class I or II. Doppler echocardiography, performed in 62 of 76 survivors, showed thin and mobile leaflets in all patients and trivial or mild regurgitation in four (6%). The mean gradient across the Medtronic Intact valves (Medtronic Blood Systems Inc., Minneapolis, Minn.) in the aortic position was 17 +/- 5.2 mm Hg, in the mitral position 3.8 +/- 1.33 mm Hg, and in the tricuspid position 4.1 +/- 1.14 mm Hg. We conclude that early results with the Intact valve are encouraging.

Assessment and follow-up of patients with ventricular septal defect and elevated pulmonary vascular resistance

Cardiac catheterization was undertaken in 87 patients (for a total of 89 studies) with ventricular septal defects, including 58 patients with moderate or severe elevation of pulmonary arteriolar resistance. When resting resistance was less than or equal to 7.9 U . m2, it always decreased with isoproterenol and no postoperative problems were experienced with pulmonary vascular obstructive disease. In 36 patients resting resistance measured greater than or equal to 8 U . m2. In 17 of these patients it decreased to less than 7 U . m2 with isoproterenol. Fifteen patients were operated on and postoperative problems with pulmonary vascular disease were experienced only in the single patient whose repair broke down. Surgery was undertaken in 4 of 19 patients in whom resistance did not decrease to less than 7 U . m2 with isoproterenol and advanced pulmonary vascular disease was evident in the 3 patients with follow-up observation. Correlation between measured resistance and other hemodynamic parameters was only fair. A pulmonary to systemic resistance ratio greater than or equal to 0.75 always indicated high absolute resistance but resistance ratios less than 0.75 were found quite frequently in the group with limited response to isoproterenol. These data argue that a reliable estimate of resistance, less than 7 U . m2, with a vasodilator predicts a good postoperative response regardless of measurements at rest or other hemodynamic parameters. Although observations on postoperative progress of patients with resistance greater than 7 U . m2 with a vasodilator are limited, a good postoperative course is unlikely unless resistance can be lowered to a level close to 7 U . m2.

Inheritance of hypertrophic cardiomyopathy: a cross sectional and M mode echocardiographic study of 50 families

To determine the mode of inheritance of hypertrophic cardiomyopathy 193 first degree relatives (parents, siblings, and offspring) of 50 patients with hypertrophic cardiomyopathy were assessed by clinical examination, electrocardiography, M mode and cross sectional echocardiography, and necropsy when available. Thirty nine (20%) first degree relatives had hypertrophic cardiomyopathy--37% of parents, 25% of siblings, and 8% of offspring. Eight (23%) of 35 affected relatives diagnosed by echocardiography had normal clinical and electrocardiographic findings. In the total study group 43% of the male population and 30% of the female population were affected. This difference is statistically significant. In 28/50 families there was familial occurrence of hypertrophic cardiomyopathy. Familial occurrence was demonstrated in 17 of 18 families in which five or more family members were assessed. In 15 families the pattern of inheritance was consistent with an autosomal dominant trait; in the other 13 the affected members were identified in a single generation and the pattern of inheritance could not be determined.

What contribution has cardiac surgery made to the decline in mortality from coronary heart disease?

The number of deaths from coronary artery disease is declining in New Zealand as in some other Western countries. It has been estimated that in 1981 in the Auckland metropolitan area there were 126 fewer deaths than would have been expected from the data in 1974. The contribution made by cardiac surgery to this decline was assessed from the known numbers of patients who were operated on, from their survival rate, and from the predicted mortality of the surgical cohort had they not undergone operation. Such mortality was predicted from past studies of patients with similar symptoms, exercise data, studies of unstable angina, and the coronary artery surgical study registry. From this method it was estimated that coronary surgery accounted for 26% to 42% of the reduction in coronary deaths. Two previous studies estimated, from calculations based on the European study of patients with modest symptoms, that the contribution of cardiac surgery was much lower. Extrapolating data from one subset of patients to a second subset with quite different characteristics is a conceptual fallacy.

A familial syndrome of cardiac myxomas, myxoid neurofibromata, cutaneous pigmented lesions, and endocrine abnormalities

A family syndrome of cardiac myxomas, myxoid neurofibromata, cutaneous pigmented lesions, and endocrine abnormalities is described. Three cases from a family of four are presented. All had cutaneous pigmented lesions. The mother had left and right atrial myxomata, her daughter a left ventricular myxoma, subcutaneous myxoid neurofibromata, and mammary fibroadenosis, and her son has no evidence of cardiac myxoma. Elevated circulating levels of insulin-like growth factors in the one family member tested raises the possibility of abnormal stimulation of somatic growth and may be linked to development of soft tissue neoplasms in these patients.