Exercise performance after septal myotomy and myectomy in patients with obstructive hypertrophic cardiomyopathy

The effect of left ventriculomyotomy and myectomy on exercise capacity and cardiac function in patients with obstructive hypertrophic cardiomyopathy has not previously been determined. In this study, 29 patients were evaluated during graded treadmill exercise before and after operation. Postoperatively, 27 of 29 patients reported symptomatic improvement and had greatly reduced left ventricular outflow gradient. Twenty-five of 28 patients (89 percent) attained higher exercise levels after operation, and this was accompanied by an increase in total body oxygen consumption from 16 to 21 ml/min per kg (P less than 0.005). A significant increase in cardiac index during maximal exercise also accompanied this improved exercise performance (5.0 to 5.7 liters/min per m2, P less than 0.05). The increase in maximal cardiac index was associated with greater desaturation of mixed venous blood (34 to 24 percent, P less than 0.02) in patients with preoperative angina. At a given level of mixed venous oxygen saturation (30 percent), overall mean cardiac index was higher postoperatively (4.6 to 5.2 liters/min per m2, P less than 0.05). These results suggest that, although several mechanisms probably contribute to symptomatic improvement after myotomy and myectomy, enhanced cardiac performance plays an important role in the majority of patients.     

Effect of biventricular pacing on symptoms and cardiac remodelling in patients with end-stage hypertrophic cardiomyopathy

BACKGROUND: Biventricular (BiV) pacing is an established therapy for heart failure in ischaemic and dilated cardiomyopathy. Its effects in end-stage hypertrophic cardiomyopathy (HCM) are unknown. AIMS: To assess the potential benefits of BiV pacing in patients with symptomatic end-stage HCM. METHODS: Twenty patients with non-obstructive HCM (12 male, mean age 57+/-13 years), left bundle branch block and symptoms of heart failure refractory to medical therapy underwent implantation of a BiV device. NYHA class, echocardiographic parameters and exercise capacity were assessed before and after implantation. RESULTS: At a mean follow-up of 13+/-6 months, an improvement of at least one NYHA class was reported in 8 (40%) patients. A clinical response was associated with an increase in ejection fraction (from 41+/-14% to 50+/-12%, p=0.009), and reductions in left ventricular end-diastolic diameter (from 57+/-6 mm to 52+/-7 mm, p=0.031) and left atrial diameter (from 65+/-8 mm to 57+/-6 mm, p=0.005). Percentage predicted peak oxygen consumption was unchanged in responders but significantly declined in non-responders (p=0.029). CONCLUSIONS: BiV pacing improved heart failure symptoms in a significant proportion of patients with end-stage HCM. Symptomatic improvement was associated with reverse remodelling of the left atrium and ventricle.     

Effect of steroid therapy on exercise performance in patients with irreversible chronic obstructive pulmonary disease

Many patients with irreversible chronic obstructive pulmonary disease (COPD) claim symptomatic improvement with steroid therapy, despite a lack of objective improvement in their spirometric data. To determine if steroids actually increase the exercise capacity of these individuals, 13 clinically stable patients (mean age, 63 +/- 4 years; 12 male patients) were given methylprednisolone (32 mg once daily) or placebo in a randomized double-blind crossover fashion. Spirometric data and minute ventilation, oxygen consumption (VO2), carbon dioxide production, and heart rate during incremental exercise were measured at each visit. Methylprednisolone did not produce a significant change in any of the measured parameters. Three patients had an increase in maximal VO2 of greater than 2 ml/kg/min during therapy with methylprednisolone, while two experienced a decline in maximal VO2 of similar magnitude. The change in exercise capacity was unrelated to the change in the forced expiratory volume in one second in individual patients (r = 0.08). We conclude that in the absence of any improvement in the usual tests of airway mechanics, steroid therapy does not improve exercise performance in patients with COPD.     

Atrial septostomy as a bridge to lung transplantation in patients with severe pulmonary hypertension.

Long waiting times for lung transplantation have limited the survival of patients with advanced pulmonary hypertension. Atrial septostomy has been used in this group of patients in an attempt to prolong survival. We evaluated the results of atrial septostomy in 12 patients using the static graded balloon dilation technique. Between December 1990 and May 1998, 10 women and 2 men (ages 13 to 56 years, mean 37 years) underwent atrial septostomy. Nine patients had primary and 3 patents had secondary pulmonary hypertension. Five patients deteriorated despite long-term intravenous prostacyclin infusions. The atrial septum was crossed with a Brockenbrough needle, followed by an 0.035-J exchange wire and progressively larger catheter balloons for atrial septal dilation, until systemic oxygen saturation decreased 5% to 10%. An atrial septal defect was successfully created in each patient. The mean right atrial pressure decreased from 23 to 18 mm Hg and the mean systemic oxygen saturation decreased from 93% to 85%. The mean cardiac index increased from 1.7 to 2.1 L/min/m2 and the mean systemic oxygen transport increased from 268 to 317 ml/min/m2. Complications occurred in 3 patients: transient hypotension during transesophageal echocardiography, a femoral pseudoaneurysm, and a femoral arteriovenous fistula. After septostomy, 6 patients had clinical improvement (resolution of ascites, edema, and no further episodes of syncope); 5 of these 6 patients underwent lung transplantation a mean of 6.1 months after septostomy. Six patients did not have clinical improvement after septostomy. Atrial septostomy improves the hemodynamic status and may be useful as a bridge to lung transplantation in selected patients with pulmonary hypertension.     

Recommendations for weaning off cardiopulmonary support in children with fulminant myocarditis.

BACKGROUND: The purpose of this study was to determine the appropriate recommendations for weaning off cardiopulmonary support (CPS) in children with fulminant myocarditis. METHODS AND RESULTS: Four consecutive patients diagnosed with fulminant myocarditis who were treated with CPS were enrolled (mean age: 9 years). The relationships between timing of weaning from CPS and various factors, including bleeding episodes, platelet count, serum concentration of the MB isoform of creatine kinase (CK-MB), echocardiographic findings, and the mixed venous blood oxygen saturation (SvO2), were retrospectively analyzed. All patients had CPS performed safely for a mean duration of 53.1 h without exchange of the circuit. Three of the 4 patients had a bleeding episode before discontinuation. The minimum platelet count occurred during weaning in all 4 patients. The peak serum CK-MB concentration when initiating CPS was higher than the peak value on the day of weaning. Echocardiographic findings before stopping CPS were similar to those after weaning. The SvO2 was 62.5% when initiating CPS and 71.3% before weaning. CONCLUSIONS: In children with fulminant myocarditis CPS can be used without exchanging the circuit and can be discontinued before bleeding episodes become symptomatic, with improvement in the biomarkers and SvO2 on weaning off CPS.     

Toxicity of mycophenolate mofetil in patients with inflammatory bowel disease

Trials of mycophenolate mofetil (MMF) in inflammatory bowel disease (IBD) suggest that it may be useful in patients intolerant of azathioprine. We examined the safety and efficacy of MMF in IBD patients intolerant of or unresponsive to azathioprine. Twelve patients [seven with Crohn's disease (CD); seven women; mean age 40 years, range 14-76 years] were treated with MMF 500 mg b.i.d. for a mean of 12.5 weeks. Intolerance was defined as the development of side effects that resolved on discontinuing MMF. Improvement was described as symptomatic improvement, decreased steroid use, or disease entering endoscopic remission. Four patients responded with symptomatic improvement and reduced steroids or mesalazine requirement. Three patients developed headache, nausea, or arthralgia. Three patients developed profuse bloody diarrhea, and in two cases with previously quiescent ulcerative colitis (UC), the source was shown to be ulcers in a drug-induced colitis with histologic features similar to those previously reported in four renal transplant patients on MMF. There is no clear evidence of efficacy of MMF in the treatment of IBD, and its use in this condition should be confined to a randomized controlled trial. Moreover, as patients with UC may be unduly prone to colonic injury, MMF may not be a suitable drug for its treatment.     

Percutaneous Interventions in Adults with Complex Cyanotic Congenital Heart Disease

Background. Adult patients with complex cyanotic heart disease present unique anatomic and physiological challenges. Changes in pulmonary blood flow over time may cause progressive cyanosis and exercise intolerance. The utility of percutaneous intervention in palliating adults with complex anatomy is unknown. Methods. This is a single‐center case series of percutaneous interventions in adults with complex cyanotic heart disease. Six patients (5 males, 1 female) underwent a total of 9 percutaneous interventions. Three patients required a second intervention 2, 10, and 13 months after the first intervention. Patients were followed a mean of 35 months after the first intervention. Results. Eight interventions were performed for diminished pulmonary blood flow and 1 intervention was performed for excessive pulmonary blood flow. Age at first intervention ranged from 28 to 48 years. Procedural success rate was 100%. There were no procedure‐related complications. Mean oxygen saturation increased from 77% prior to the procedure to 86% after the intervention. All patients experienced symptomatic improvement. There was 1 late sudden death 17 months post procedure. Conclusions. Percutaneous intervention can be performed safely and improves symptoms and oxygenation in adults with complex cyanotic heart disease.     

Percutaneous double balloon tricuspid valvotomy for severe tricuspid stenosis: 3-year follow-up study

We performed percutaneous double balloon tricuspid valvotomy in four patients (36 +/- 12 years of age), with severe symptomatic rheumatic tricuspid stenosis and mild mitral valve disease. Two 9F Meditech balloon catheters, 15-20 mm diameter, were positioned simultaneously across the tricuspid valve and inflated up to five atmospheres pressure achieving valvotomy. After balloon valvotomy there was symptomatic improvement, and the Doppler tricuspid valve area was increased from a mean of 1 +/- 0.2 to 2.2 +/- 0.2 cm2 (P less than 0.001). At 3-year follow-up the symptomatic improvement persisted and the mean tricuspid valve area was maintained at 2.2 +/- 0.1 cm2. During the follow-up period there was no increase in degree of tricuspid regurgitation assessed by colour Doppler. We conclude that 3 years after balloon valvotomy of the tricuspid valve, the 120% increase in valve area persists, with no objective evidence of restenosis.     

Changes in gastric emptying in recipients of successful combined pancreas-kidney transplants.

Gastroparesis causes gastric emptying disorders in patients with chronic diabetes mellitus and it results from reduced smooth muscle contractility secondary to autonomic dysfunction. Today there has been little objective evidence of improvement in gastric emptying following correction of both uremia and diabetes by combined kidney-pancreas transplantation. We used gastrointestinal symptom scores, solid gastric emptying tests and electrogastrography to evaluate the effect of combined kidney-pancreas transplantation on gastric emptying in 8 uremic diabetic patients. The mean age of the patients was 40 years (range: 30-51 years) and the mean duration of diabetes was 24 years (range: 16-30 years). The patients had been on dialysis up to 24 months. The pretransplant A1 mean was 6.5 before improving to 4.3 after transplantation. All patients were receiving exogenous insulin. Our study data indicate that uremic diabetics have a high prevalence of symptomatic gastrointestinal dysfunction including abnormalities of gastric emptying and gastric electrical activity. Following transplantation, the gastrointestinal symptomatology improved significantly. Significant improvement in the rate of gastric emptying also correlated with improvement in the symptom complex. Gastric electrical activity also improved during the follow-up period.     

Long-term outcome of patients undergoing balloon mitral valvotomy in pregnancy

The outcome of 36 patients (mean age 25.8 +/- 4.3 years) who underwent balloon mitral valvuloplasty during pregnancy is described in this report. The procedure was successful in 35 patients (97.2%), with no maternal mortality, and all patients subsequently had symptomatic improvement and uneventful deliveries. The children had normal growth and development at a follow up of 2.8 +/- 3.3 years. Thus, in patients with symptomatic severe mitral stenosis, balloon mitral valvuloplasty is feasible, safe, and effective with good long-term outcomes for both the mother and the fetus.     

Long-term effect of bosentan in pulmonary hypertension associated with complex congenital heart disease

BackgroundBosentan is recommended for symptomatic patients with Eisenmenger syndrome due to simple congenital lesions such as atrial and ventricular septal defects (VSD). However, its long-term efficacy and safety in patients with pulmonary arterial hypertension (PAH) associated with complex congenital heart disease (CHD) is unknown.ObjectivesWe examined the short- and long-term effects and safety profile of bosentan in patients with PAH and complex CHD.MethodsWe followed 14 patients with PAH and complex CHD for a mean of four years. Demographic parameters, exercise capacity assessed by the six-minute walking test (6MWT) and oxygen saturation were assessed at baseline, six months and at follow-up.ResultsMean age was 37.1±11.7 years; 90% were in WHO class III or IV. The most common diagnosis was pulmonary atresia with VSD (35.7%), followed by truncus arteriosus (28.6%), patent ductus arteriosus (21.4%) and transposition of the great arteries (14.3%). After six months of treatment, six-minute walking distance (6MWD) increased from 371.9 to 428.4 m (p=0.005) and functional class was improved (p=0.005). After four years, one patient discontinued bosentan due to side effects and four patients were started on sildenafil, after a mean 38 months of bosentan treatment. Mean 6MWD for patients on bosentan monotherapy (n=8) was 440.1±103.8 m, whereas for patients on bosentan-sildenafil combination therapy (n=4) it was 428.8±96.9 m, after four years of therapy. Two patients died during follow-up.ConclusionsBosentan was safe and was associated with improved exercise capacity in patients with PAH and complex CHD. This improvement was sustained for up to four years and the safety profile was similar to simple CHD patients.     

Mitral balloon valvuloplasty for patients aged over 70 years: an alternative to surgical treatment

We report the results and one-year follow-up of 20 elderly patients (age range 70-82 years) with severe rheumatic mitral stenosis treated by mitral balloon valvuloplasty (MBV). All 20 were breathless at rest despite treatment with diuretics and digoxin. At cardiac catheterization, successful dilatation was achieved in 17 patients: mean transvalvular mitral gradient fell by 45%, mean cardiac output rose by 24% and mean valve area increased by 76%. There was no procedure-related mortality. At one month, 15 patients had experienced an improvement in symptoms of at least one New York Heart Association class and, at one year, ten had maintained this improvement. Three patients proceeded to mitral valve replacement because of a suboptimal symptomatic result. Mitral balloon valvuloplasty can be successfully performed with significant symptomatic benefit in frail elderly patients unfit for surgery and may also be offered to other selected elderly patients as an alternative to surgical treatment.     

Lung function 4 years after lung volume reduction surgery for emphysema

STUDY OBJECTIVES: Current data for patients > 2 years after lung volume reduction surgery (LVRS) for emphysema is limited. This prospective study evaluates pre-LVRS baseline data and provides long-term results in 26 patients. INTERVENTION: Bilateral targeted upper lobe stapled LVRS using video thoracoscopy was performed in 26 symptomatic patients (18 men) aged 67 +/- 6 years (mean +/- SD) with severe and heterogenous distribution of emphysema on lung CT. Lung function studies were measured before and up to 4 years after LVRS unless death intervened. RESULTS: No patients were lost to follow-up. Baseline FEV(1) was 0.7 +/- 0.2 L, 29 +/- 10% predicted; FVC, 2.1 +/- 0.6 L, 58 +/- 14% predicted (mean +/- SD); maximum oxygen consumption, 5.7 +/- 3.8 mL/min/kg (normal, > 18 mL/min/kg); dyspneic class > or = 3 (able to walk < or = 100 yards) and oxygen dependence part- or full-time in 18 patients. Following LVRS, mortality due to respiratory failure at 1, 2, 3, and 4 years was 4%, 19%, 31%, and 46%, respectively. At 1, 2, 3, and 4 years after LVRS, an increase above baseline for FEV(1) > 200 mL and/or FVC > 400 mL was noted in 73%, 46%, 35%, and 27% of patients, respectively; a decrease in dyspnea grade > or = 1 in 88%, 69%, 46%, and 27% of patients, respectively; and elimination of oxygen dependence in 78%, 50%, 33%, and 22% of patients, respectively. The mechanism for expiratory airflow improvement was accounted for by the increase in both lung elastic recoil and small airway intraluminal caliber and reduction in hyperinflation. Only FVC and vital capacity (VC) of all preoperative lung function studies could identify the 9 patients with significant physiologic improvement at > 3 years after LVRS, respectively, from 10 patients who responded < or = 2 years and died within 4 years (p < 0.01). CONCLUSIONS: Bilateral LVRS provides clinical and physiologic improvement for > 3 years in 9 of 26 patients with emphysema primarily due to both increased lung elastic recoil and small airway caliber and decreased hyperinflation. The 9 patients had VC and FVC greater at baseline (p < 0.01) when compared to 10 short-term responders who died < 4 years after LVRS.     

Preliminary experience with endoscopic stent placement in benign pancreatic diseases

We treated 35 patients with endoscopic stent placement across the major or minor papilla in an attempt to relieve suspected partial obstruction to pancreatic duct drainage in patients with pancreatitis. The patients subsequently have been followed for periods ranging from 6 months to 3 years (mean, 14 months). Endoscopic stents were successfully placed across the minor papilla in 19 of 22 patients with pancreas divisum associated with acute recurrent pancreatitis (19) and severe abdominal pain (3). 17 patients had symptomatic improvement manifested by a decrease in frequency of attacks of pain and emergency admission. Stents were placed through the major papilla in 14 of 15 patients with recurrent pancreatitis related to a variety of causes. 8 of the 14 patients improved during the follow-up period, including 4 of 5 patients with alcoholic pancreatitis complicated by a segmental stricture.     

Efficacy and safety of bosentan for pulmonary arterial hypertension in adults with congenital heart disease

The dual endothelin receptor antagonist, bosentan, has been shown to be well tolerated and effective in improving pulmonary arterial hypertension (PAH) symptoms in patients with Eisenmenger syndrome but data from longer-term studies are lacking. The aim of this study was to retrospectively analyze the long-term efficacy and safety of bosentan in adults with PAH secondary to congenital heart disease (PAH-CHD). Prospectively collected data from adult patients with PAH-CHD (with and without Down syndrome) initiated on bosentan from October 2007 through June 2010 were analyzed. Parameters measured before bosentan initiation (62.5 mg 2 times/day for 4 weeks titrated to 125 mg 2 times/day) and at each follow-up (1 month and 3, 6, 9, 12, 18, and 24 months) included exercise capacity (6-minute walk distance [6MWD]), pretest oxygen saturation, liver enzymes, and hemoglobin. Data were analyzed from 39 patients with PAH-CHD (10 with Down syndrome) who had received ≥ 1 dose of bosentan (mean duration of therapy 2.1 ± 1.5 years). A significant (p < 0.0001) average improvement in 6MWD of 54 m over a 2-year period in patients with PAH-CHD without Down syndrome was observed. Men patients had a 6MWD of 33 m greater than women (p < 0.01). In all patients, oxygen saturation, liver enzymes, and hemoglobin levels remained stable. There were no discontinuations from bosentan owing to adverse events. In conclusion, patients with PAH-CHD without Down syndrome gain long-term symptomatic benefits in exercise capacity after bosentan treatment. Men seem to benefit more on bosentan treatment. Bosentan appears to be well tolerated in patients with PAH-CHD with or without Down syndrome.     

The use of nifedipine in patients with Eisenmenger's syndrome complicating patency of the arterial duct

Nifedipine has a vasodilatory effect on both the systemic and the pulmonary circulation. Its preferential effect on reducing the pulmonary vascular resistance has been studied in patients with primary pulmonary hypertension. In 4 patients with the Eisenmenger's syndrome complicating patency of the arterial duct (ductus arteriosus), we have studied the possibility of this selective pulmonary vasodilatory effect of nifedipine in reducing the right-to-left shunting. The degree of differential cyanosis was taken to reflect the right-to-left shunting. This was assessed continuously by 2 pulse oximeters applied to the right arm and leg. After sublingual nifedipine, the oxygen saturation of the right leg increased from pretreatment value of 79 +/- 5% (mean +/- SEM) to a maximum of 84 +/- 3% (P less than 0.01). Such a beneficial effect was maximal in the first 2 hours. On maintenance therapy, symptom-limited cycle ergometry showed increased exercise duration with comparable degrees of arterial desaturation and there was symptomatic improvement. This improvement disappeared on changing to placebo. It was concluded that nifedipine reduced right-to-left shunting and improved symptomatology.     

Determinants of delayed improvement in exercise capacity after percutaneous transvenous mitral commissurotomy

BACKGROUND: Percutaneous transvenous mitral commissurotomy (PTMC) results in short-term hemodynamic and symptomatic improvements. We have previously shown that the immediate symptomatic relief is related to the improvement in excessive exercise ventilation. The exercise capacity, however, does not improve in the short term but does improve gradually over several months. The pathophysiologic basis for the delayed improvement in exercise capacity has not been fully evaluated. METHODS: To elucidate the determinants of improvement in exercise capacity late after PTMC, maximal ergometer exercise with respiratory gas analysis and exercise hemodynamic measurements were performed in 22 patients with symptomatic mitral stenosis before, immediately after, and 7 months after PTMC. RESULTS: Mitral valve area increased from 0.9 +/- 0.2 cm(2) to 1.7 +/- 0.4 cm(2) after PTMC (P <.01). Significant improvements were observed in symptoms, cardiac output at peak exercise (6.6 +/- 1.5 L/min vs 8.6 +/- 1.9 L/min, P <.01), and mean pulmonary artery pressure at peak exercise (54.1 +/- 15.6 mm Hg vs 42.3 +/- 9.5 mm Hg, P <.01) immediately after PTMC. Excessive exercise ventilation, as assessed by the slope of the regression line between expired minute ventilation and carbon dioxide output (VE-VCo(2)), decreased significantly from 38.2 +/- 8.2 to 33.3 +/- 4.9 (P <.01). There were no significant changes in peak oxygen uptake (from 17.5 +/- 3.2 mL/kg per minute to 17.9 +/- 3.6 mL/kg per minute) immediately after PTMC. At 7 months, improved mitral valve area, symptoms, cardiac output at peak exercise, mean pulmonary artery pressure at peak exercise, and VE-VCo(2) were unchanged compared with values immediate after PTMC. Significant improvement was observed in peak oxygen uptake (19.7 +/- 3.0 mL/kg per minute [P <.01 compared with pre-PTMC or immediate post-PTMC values]). The increase in exercise cardiac output or the decrease in pulmonary artery pressure was not correlated with the late improvement in peak oxygen uptake. The short- or long-term improvements in VE-VCo(2), however, were significantly correlated with the late improvement in peak oxygen uptake. CONCLUSIONS: Our results suggest that ventilatory improvement, not increased exercise cardiac output, contributed at least in part to the late improvement in exercise capacity after PTMC.     

Long-term results of the "palliative" Mustard operation

A long-term follow-up study after 41 palliative Mustard operations for transposition of the great arteries and pulmonary vascular obstructive disease is presented. The operations were performed from 1973 to 1980. Mean pulmonary arteriolar resistance was 13.96 +/- 6.7 Um2. A ventricular septal defect was not closed in 34 patients; in 7 it was created at operation. There were three hospital and two late deaths. Survivors were followed up for 3 to 10 years (mean 76.7 +/- 22.8 months). Before operation 4 children were in New York Heart Association functional class IV and 33 were in class III. Mean hemoglobin concentration was 19.43 +/- 3.14 g/dl and arterial oxygen saturation was 63.44 +/- 11.29%. After operation 18 patients were in functional class I, 17 in class II and only 1 in class III. Hemoglobin level decreased to 14.19 +/- 2.3 g/dl and arterial oxygen saturation improved to 89.12 +/- 7.25%. Cardiac catheterization in 21 survivors confirmed no change in pulmonary artery pressure and resistance. Effective pulmonary blood flow improved from 1.39 +/- 0.39 before to 2.6 +/- 0.78 liters/min per m2 after operation. The palliative Mustard operation carries a low risk and provides excellent symptomatic improvement up to 10 years in patients with transposition of the great arteries and pulmonary vascular disease.     

Growth and tissue abnormalities in young people with cyanotic congenital heart disease receiving systemic-pulmonary artery shunts

The effects of systemic-pulmonary artery shunts on growth, body composition, and adipose tissue were studied in 29 children, aged 2 to 16 years, with cyanotic congenital heart disease. Of these, 16 received surgical shunts and 13 were unoperated. Postoperatively, all patients who received shunts were better oxygenated (systemic oxygen saturation 69 ±11% preoperatively and 84 ± 4% postoperatively; mean ± standard error of the mean) and were symptomatically improved. However, the groups were not significantly different in height, weight, lean body mass, total body fat, $\text{lean}\text{fat}$ ratio, cellular lipid content, or total number of lipid-con-taining fat cells. Age at operation did not seem to influence the effects of surgery. These observations suggest that growth and certain measurements of tissue development were unaffected by surgical systemic-pulmonary artery shunts despite increased oxygenation and symptomatic improvement after operation.     

Hydroxyurea therapy for management of secondary erythrocytosis in cyanotic congenital heart disease

Secondary erythrocytosis in cyanotic congenital heart disease (CCHD) causes substantial morbidity because of complications of hyperviscosity, including stroke and chronic end organ damage. Phlebotomy provides temporary improvement but leads to iron deficiency and can actually increase blood viscosity. We describe the successful use of hydroxyurea (hydroxycarbamide) in four patients with uncorrected CCHD and symptomatic secondary erythrocytosis. In all patients, hydroxyurea improved symptoms of hyperviscosity. Substantial decreases in the red blood cell (RBC) count were observed, along with increases in the mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH), leading to only modest declines in the circulating hemoglobin concentration. Two patients experienced transient mild myelosuppression, which promptly resolved with dose reduction of hydroxyurea. Hydroyxurea provides a novel and useful therapeutic approach to reduce hyperviscosity from secondary erythrocytosis in patients with CCHD, while preserving oxygen carrying capacity and avoiding iron depletion by phlebotomy.