The role of chronotropic impairment during exercise after the Mustard operation.

To better understand the role of chronotropic impairment on exercise performance after the atrial switch (Mustard) operation, 20 patients who had undergone this operation for uncomplicated d-transposition of the great arteries exercised to maximal volition using a 1 min incremental treadmill protocol. Heart rate, oxygen consumption, carbon dioxide production and minute ventilation were monitored continuously. Two-dimensional echocardiograms were obtained before testing to calculate the right ventricular inflow volume indexed to body surface area. All patients achieved maximal aerobic capacity based on their ventilatory patterns and respiratory exchange ratio. Maximal heart rate was reduced (175 beats/min; 87% of predicted for age) and maximal oxygen consumption was decreased (31 ml/kg per min; 75% of predicted for age and gender). There was no correlation between maximal oxygen consumption and maximal heart rate. Right ventricular volume index, however, had a significant inverse correlation with maximal heart rate (r = -0.62, p less than 0.005). There was no correlation between right ventricular volume index and heart rate at rest. These results suggest that decreased maximal oxygen consumption in patients after the Mustard procedure is not a result of chronotropic impairment. Right ventricular dilation may be a compensatory response to chronotropic impairment.

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

OBJECTIVES: The purpose of this study was to assess myocardial blood flow (MBF) and flow reserve in systemic right ventricles (RV) in long-term survivors of the Mustard operation. BACKGROUND: There is a high prevalence of systemic RV dysfunction and impaired exercise performance in long-term survivors of the Mustard operation. A mismatch between myocardial blood supply and systemic ventricular work demand has been proposed as a potential mechanism. METHODS: We assessed MBF at rest and during intravenous adenosine hyperemia in 11 long-term survivors of a Mustard repair (age 18+/-5 years, median age at repair 0.7 years, follow-up after repair 17+/-5 years) and 13 healthy control subjects (age 23+/-7 years), using N-13 ammonia and positron emission tomography imaging. RESULTS: There was no difference in basal MBF between the systemic RV of survivors of the Mustard operation and the systemic left ventricle (LV) of healthy control subjects (0.80+/-0.19 vs. 0.74+/-0.15 ml/g/min, respectively, p = NS). However, the hyperemic flows were significantly lower in systemic RVs than they were in systemic LVs (2.34+/-0.0.69 vs. 3.44+/-0.62 ml/g/min respectively, p < 0.01). As a result, myocardial flow reserve was lower in systemic RVs than it was in systemic LVs (2.93+/-0.63 vs. 4.74+/-1.09, respectively, p < 0.01). CONCLUSIONS: Myocardial flow reserve is impaired in systemic RVs in survivors of the Mustard operation. This may contribute to systemic ventricular dysfunction in these patients.

The modified Fontan operation for children less than 4 years old.

Of 500 patients who had a modified Fontan operation at this institution between 1973 and 1987, 54 (33 boys and 21 girls) were less than 4 years old. This retrospective study related preoperative clinical and hemodynamic data to subsequent survival. Twenty patients less than 4 years old had tricuspid atresia, 13 had double inlet ventricle and 21 had other complex heart defects. There were 14 early deaths (less than 30 days after operation) and 6 late deaths. Multivariate analysis of survival for the entire group of 500 patients revealed the following factors to be significantly associated with poorer survival: absence of tricuspid atresia (p = 0.011), asplenia (p less than 0.001), age less than 4 years at operation (p = 0.042), atrioventricular valve dysfunction (p = 0.017), early calendar year of operation (p less than 0.001) and the presence of either one or more of the following: left ventricular ejection fraction less than 60%, mean pulmonary artery pressure greater than 15 mm Hg and pulmonary arteriolar resistance greater than 4 U.m2 (p less than 0.001). On the basis of this study of 500 patients, age less than 4 years at operation appears to be an independent risk factor for poorer survival after the modified Fontan operation.

Results of the modified Fontan operation in adults.

The results of the modified Fontan procedure were examined in 77 patients 18 years of age and older who underwent operation at this institution between October 1973 and December 1986. This series represents 16% of the patients undergoing the modified Fontan operation during that period. Of the 77 patients (46 men and 31 women), 29 had tricuspid atresia, 30 had double-inlet ventricle and 18 had other complex lesions. There were 5 (6%) hospital deaths, compared with 67 (17%) for patients of all ages undergoing the Fontan operation during the same period. Patient age 18 years and older was not a significant risk factor. There were 8 late deaths. Detailed follow-up data were available on 61 (95%) survivors from 5 months to 12 years (mean 4 years) postoperatively. Fifty-seven (93%) of the patients were in New York Heart Association class I or II, 20 (33%) were taking no medication and 11 (18%) were taking digoxin alone. Seventeen (28%) patients complained of persistent ascites or edema. The study indicated that (1) the modified Fontan operation can be performed with low mortality in adults, (2) the long-term outcome is favorable and (3) persistent ascites or edema may be a problem in some patients.

Aortic root dilation after the Ross procedure.

This study evaluated changes in neoaortic root geometry in patients who underwent the Ross procedure. Serial postoperative echocardiographic measurements of the neoaortic root indexed to the square root of body surface area (centimeters divided by meters) were obtained from 30 patients (age range 3.1 to 31.4 years) and compared with paired preoperative and immediate postoperative values. Normal aortic root diameter Z scores were derived from root dimensions obtained from 217 healthy controls. Compared with preoperative values, an immediate stretch of the neoaortic versus pulmonary root (annulus and sinuses of valsalva) was observed at a mean follow-up period of 1 week. Additional aortic annular dilation from baseline prehospital discharge values was observed at 2 to 12 months (baseline vs follow-up annulus Z score: 1.4 vs 2.6, p <0.01, n = 16) and at 16 to 33 months follow-up (0.8 vs 2.0, p <0.05, n = 12). In a similar fashion, there was additional enlargement of the aortic sinus from its stretched state at hospital discharge at 2 to 12 months (baseline vs follow-up sinus Z score: 2.0 vs 3.3, p <0.01, n = 17) and at 16 to 33 months (1.7 vs 3.0, p <0.01, n = 13). There were no differences in root size between 2 to 12 and 16 to 33 months after surgery. There was a decrease in left ventricular size with no alteration in blood pressure or degree of aortic valve regurgitation. Thus, aortic root dilation occurs up to the first year after the Ross procedure but does not appear to progress beyond this time.

Utility of temporary atrial epicardial electrodes in postoperative pediatric cardiac patients.

The utility of atrial electrograms recorded from temporary bipolar atrial epicardial electrodes in postoperative pediatric cardiac patients was assessed by (1) examining the accuracy of the surface electrocardiographic tracings and (2) analyzing the treatment modalities used for the arrhythmias diagnosed on the basis of the atrial electrograms. Atrial electrograms were obtained simultaneously with single-lead surface electrocardiographic recordings from 20 pediatric patients (ages 7 months to 11 years) after intracardiac repair of congenital heart defects. Interpretations of 25 surface recordings by five pediatric cardiologists were compared with analyses of the electrograms. Sinus rhythm was interpreted correctly by most reviewers 100% of the time, whereas atrioventricular conduction disturbances and narrow QRS tachycardias were identified correctly 77% and 14% of the time, respectively. Of those rhythms incorrectly interpreted, 89% had some type of active therapeutic intervention. Single-lead surface electrocardiographic recordings are imprecise for evaluating postoperative rhythms in pediatric cardiac patients, and our experience suggests that rhythms for which active intervention is necessary may be more difficult to interpret correctly by surface monitoring alone.

Aortico-left ventricular tunnel: diagnosis based on two-dimensional echocardiography, color flow Doppler imaging, and magnetic resonance imaging.

Aortico-left ventricular tunnel is a rare congenital cardiac lesion that often results in severe aortic insufficiency in infancy. In previously reported cases, the diagnosis has often been missed initially despite use of cardiac catheterization and angiography. We describe a patient who underwent successful surgical correction of this malformation at 10 months of age after the diagnosis had been established by use of two-dimensional echocardiography, color flow Doppler imaging, and magnetic resonance imaging. Aortico-left ventricular tunnel can be diagnosed by use of these noninvasive means without cardiac catheterization.

Palliative transposition of venous return. Long-term follow-up.

A palliative operation to create intraatrial transposition of venous return without concomitant closure of an associated ventricular septal defect (palliative Mustard or Senning operation) has been used primarily for patients with a combination of transposition of the great arteries, ventricular septal defect, and pulmonary vascular obstructive disease. We evaluated the results in all 15 patients (median age 13 years) who had this procedure at the Mayo Clinic between 1973 and 1979. There were two (13%) operative deaths. One patient was lost to long-term follow-up. Of the 12 operative survivors for whom follow-up data were available, 11 reported subjective improvement in exercise tolerance and activity level. There were seven late deaths: six from cardiovascular problems and one from an accident. There are five survivors currently alive (average 10.8 years after operation). Patients who survived the operation for more than 5 years had a significantly (p less than 0.05) lower pulmonary resistance preoperatively than those who survived less than 5 years. The hemoglobin level decreased from 21.1 gm/dl before operation to 18.4 gm/dl, and arterial saturation was increased from 64% to 85% at an average of 9 years after operation. We conclude that this operation produces subjective improvement and lessens hypoxemia and polycythemia. In some patients, palliation may be achieved for 10 years or longer.

Tetralogy of Fallot with anomalous origin of left anterior descending coronary artery. Surgical options.

Anomalous origin of the left anterior descending coronary artery from the right coronary artery can interfere with the location of the usual ventriculotomy during repair of tetralogy of Fallot. The purpose of this study was to compare the results of two operative techniques: (1) a "tailored" right ventricular incision and outflow patch reconstruction and (2) placement of a conduit from the right ventricle to the main pulmonary artery. We reviewed the records of 416 patients who had complete repair of tetralogy of Fallot at the Mayo Clinic from 1973 through 1984. Twenty (5%) (median age 6.5 years) had anomalous origin of the left anterior descending coronary artery from the right coronary artery. Twelve of these patients had right ventricular outflow patch reconstruction, and eight had placement of a conduit from the right ventricle to the pulmonary artery. Three deaths occurred, all during hospitalization, two in the patch reconstruction group and one in the conduit group. The average reduction in right ventricular pressure postoperatively was slightly but not significantly greater for the conduit group. These data indicate that correction of tetralogy of Fallot with anomalous origin of the left anterior descending coronary artery can be done with either patch reconstruction or conduit placement. Selection of the more appropriate procedure depends on the exact location and degree of tortuosity of the anomalous artery and the level and severity of right ventricular outflow obstruction.

Glenn shunt: effect on pleural drainage after modified Fontan operation.

After the Fontan operation, patients who had a prior Glenn anastomosis should have less pleural drainage than patients without a prior Glenn anastomosis because innominate and pleural vein and thoracic duct pressures are unaltered in the former group. To test this hypothesis, we studied 92 patients who had had a Fontan operation between 1973 and 1986--46 with a prior Glenn anastomosis and 46 without a prior Glenn anastomosis (controls)--who were matched for age, gender, diagnosis, and number of prior shunt operations. The volume of pleural drainage was significantly less (p less than 0.05) in the patients with a prior Glenn anastomosis (median 1,959 ml or 48.2 ml/kg) than in the control patients (median, 3,220 ml or 83.4 ml/kg). Similar results were obtained among the patients matched for prior right thoracotomy (n = 28; 1,270 ml and 2,942 ml; p = 0.028). There was no significant difference between the two groups with respect to ventricular end-diastolic pressure, mean right atrial pressure, mean pulmonary artery pressure, duration of total or differential (right side versus left side) effusion, duration of hospital stay, or hospital or late death.

The modified Fontan operation for asplenia and polysplenia syndromes.

From 1975 through 1986, 49 patients with asplenia (23 patients) or polysplenia (26 patients) syndromes underwent a modified Fontan operation. All patients had anomalous systemic venous return, and 43 (88%) had anomalous pulmonary venous return. The atrioventricular valve anatomy varied: 36 patients had a common atrial chamber and common atrioventricular valve, eight had mitral valve atresia, and five had severe mitral valve hypoplasia. Redirection of systemic venous return was accomplished by (1) atrial baffle (29 patients), (2) intraatrial conduit (19 patients), and (3) extraatrial conduit (one patient). There were 21 (43%) hospital deaths overall. However, since 1985, six of 22 patients (27%) have died. Increased mortality was seen in patients requiring atrioventricular valve repair or replacement (8/11, 73%) and in patients with asplenia (65%). Lower mortality was seen in patients with polysplenia (24%) and those receiving an intraatrial conduit (26%), although this decrease also represents the more recent experience. We conclude: (1) The Fontan operation for patients with asplenia or polysplenia syndromes has resulted in a significant (although recently declining) mortality; (2) mortality is higher in patients with asplenia; (3) patients with atrioventricular valve insufficiency requiring repair or replacement are at higher risk; and (4) intraatrial conduits seem to offer promise for successfully accomplishing this repair.

The role of transthoracic echocardiography in the diagnosis of infective endocarditis in children.

BACKGROUND: Infective endocarditis (IE) is frequently suspected but infrequently diagnosed in children. Clinicians often order echocardiograms to "rule out" IE. In an era of cost constraint, clinically efficient strategies must be developed to eliminate unnecessary tests. We hypothesized that transthoracic echocardiography (TTE) is only useful in children in whom there is a high clinical suspicion of IE based on history, physical examination, and persistently positive blood cultures. OBJECTIVE: To determine the role of TTE as a screening test for suspected IE in children. METHODS: Echocardiographic reports and medical records were reviewed retrospectively for 173 consecutive patients who underwent TTE to rule out IE from January 1993 to August 1996. RESULTS: Persistent fever was the predominant symptom leading to a suspicion of IE (120 patients [69.4%]). Fifty-seven (32.9%) of the 173 patients had congenital heart disease and 95 patients (54.9%) had indwelling venous catheters. Twenty-six patients (15.0%) were diagnosed and treated for IE. Twelve (46.2%) of these 26 patients had vegetations seen on TTE. The conditions of the remaining 14 patients were diagnosed clinically and these patients had persistently positive blood cultures. By univariate analysis, the risk factors associated with the diagnosis of IE were malaise, congestive heart failure, new or changing heart murmur, leukocytosis, hematuria, and the presence of 2 or more positive blood cultures for the same organism. The risk factors associated with positive TTE were malaise, congestive heart failure, new or changing heart murmur, leukocytosis, hematuria, and 2 or more positive blood cultures. The presence of an indwelling catheter or immunocompromised status were not predictive of vegetation or IE. CONCLUSIONS: Transthoracic echocardiography has poor sensitivity as a screening test for IE in patients with low clinical probability of the disease. A diagnostic algorithm for IE is suggested based on these data.

Melanosis and hydrocephalus. Report of four cases.

Four cases are presented in which hydrocephalus and extensive pigmented lesions of the body coexisted. A related developmental defect is suggested.

Cardiac tamponade caused by serous pericardial effusion in patients on extracorporeal membrane oxygenation.

PURPOSE: Extracorporeal membrane oxygenation (ECMO) has been successful in the treatment of critically ill children; however, its use has been accompanied by a broad range of complications. The authors describe the presentation, clinical course, treatment, and outcome of 4 patients on ECMO in whom pericardial tamponade developed caused by a serous effusion. METHODS: A retrospective review of patients placed on ECMO at our institution from 1993 to 1997 was performed. The case histories of 4 patients in whom pericardial tamponade developed caused by a serous effusion were reviewed in detail. RESULTS: The first patient presented with hypotension while on venovenous (VV) ECMO. The hypotension improved with fluid resuscitation. The patient was converted from (VV) to venoarterial (VA) ECMO when hypotension recurred. After a third episode of hypotension, a narrow pulse pressure was noted, and echocardiography results confirmed a pericardial effusion. The diagnosis was recognized earlier in the course of the subsequent 3 patients. All 4 patients were treated with aspiration of serous fluid from the pericardium with an over-the-needle plastic catheter that was left in place. More than 1 aspiration was required in all cases. All 4 patients survived. CONCLUSIONS: The authors have identified a group of ECMO patients with pericardial tamponade caused by serous effusion with good response to treatment. A high index of suspicion and early echocardiography is warranted to confirm the diagnosis in a patient with hypotension on ECMO.

Pressure recovery in pediatric aortic valve stenosis.

This study was designed to evaluate the phenomenon of pressure recovery in pediatric patients with aortic stenosis and also to evaluate how observed differences between catheter and Doppler gradients can be predicted by Doppler echocardiography. Doppler measurements of aortic valve stenosis gradients are known to overestimate observed gradients in the catheterization laboratory. Pressure recovery has been shown to be a contributing factor to this discrepancy. However, the clinical relevance of correcting Doppler gradients using the pressure recovery equation has not been evaluated in the pediatric population. Simultaneously obtained catheter and Doppler gradients were studied in 14 patients (range, 0.03-18 years; mean, 4.1 years) with aortic valve stenosis. A total of 23 data points were measured because 9 patients underwent balloon valvuloplasty and had both a pre- and a post-balloon valvuloplasty data point in the study. The catheter gradients were then compared to peak, mean, and pressure recovery corrected Doppler gradients. Pressure recovery was calculated using a previously validated equation. As expected, measured echocardiographic continuous-wave peak Doppler gradients overestimated the observed catheter gradients (range, 16-93 mmHg; mean, 43 mmHg). The continuous-wave peak Doppler gradients, mean, and pressure recovery adjusted gradients were equally as good in correlating the observed catheter gradients to those obtained by Doppler echocardiography (r = 0.92). However, pressure recovery corrected Doppler gradients were in better agreement with catheter gradients than echocardiographic mean or peak Doppler gradients (95% limit of agreement: -9 to 19 mmHg for pressure recovery corrected gradients, -30 to 11 mmHg for mean Doppler gradients, and 2-83 mmHg for peak Doppler gradients). Measured continuous-wave peak Doppler gradients consistently overestimated catheter gradients. The noted differences may be predicted using the pressure recovery equation. Pressure recovery is a significant factor in children with aortic valve stenosis.

The genetic implication for preceding generations of the prenatal diagnosis of interrupted aortic arch in association with unsuspected DiGeorge anomaly.

We present a case of prenatally diagnosed interrupted aortic arch with a ventricular septal defect in the presence of maternal congenital heart disease, which led to the detection of segmental monosomy of chromosome 22q11.2 in both patients. The implications of detecting a microdeletion and the importance of a multidisciplinary approach to prenatal diagnosis and counseling are discussed.

Common cardiovascular problems in the young: Part I. Murmurs, chest pain, syncope and irregular rhythms.

Cardiovascular signs and symptoms in young people are common and usually represent variants of normal physiology. However, these signs and symptoms can also indicate the presence of important cardiovascular disorders. Innocent heart murmurs can be distinguished from pathologic murmurs by the lack of associated symptoms, as well as their loudness, timing and location. Although most chest pain in this age group is of musculoskeletal or psychogenic origin, cardiac causes can include pericarditis, aortic stenosis and coronary anomalies. Syncope is usually vasovagal in origin and has a benign prognosis. Sinus arrhythmia and isolated extrasystoles are the most common causes of irregular cardiac rhythms in the young. Multiform premature ventricular contractions, couplets and ventricular tachycardia may indicate underlying cardiac disease.