Cuff Pressures and Doppler Gradients after Coarctectomy A Long-term Follow-up

ABSTRACT. Fourty-six adult patients operated on as chidren with resection and end to end anastomosis because of coarctation of the aorta were studied. The age at operation was 7 to 13 years (mean age 10 years) and at follow-up 18 to 28 years (mean age 21 years). Arm and thigh cuff pressure was measured at rest, during and immediately after submaximal exercise. The systolic gradients were also estimated using continuous wave Doppler. Systolic blood pressure at rest was 150 mmHg or more in 12 patients (26%). The cuff pressure at rest correlated well with arm-leg gradients at rest and at work, and also with the Doppler gradients at rest. Doppler gradients slightly underestimated invasively measured gradients. The results imply that postoperative hypertension was explained by residual mechanical obstruction.     

Echocardiographic Evaluation of Systolic and Diastolic Function in Postoperative Coarctation Patients

Postoperative coarctation (CoA) patients are often found to have signs of persistent myocardial dysfunction. M-mode echocardiography was performed to study left ventricular (LV) size, mass, and systolic function and Doppler ultrasonography to study LV filling and flow velocity in the LV outflow tract and aorta in 28 ``healthy' postoperative CoA patients (5–21 years) and 28 age- and sex-matched controls. The early (E) and late (A) diastolic transmitral velocities were significantly higher in the patient group than in the controls (p < 0.05). Other diastolic parameters (isovolumic relaxation time, E/A ratio, and deceleration time of the early diastolic velocity) were similar in the two groups (p= NS). The left atrial diameter, LV wall average, end-diastolic diameter of the LV and LV mass were higher in the patients than controls (p < 0.05). The patients also had a higher stroke volume, cardiac output, and cardiac index than the controls (p < 0.01). The fractional shortening was similar in the two groups (p= NS). Blood flow velocities in both the LV outflow tract and aorta were higher in the patients than the controls (p < 0.0002). We found LV hypertrophy with signs of a hyperdynamic circulation (increased cardiac index and stroke volume) in our patients. An increase in A is associated with LV hypertrophy and seems to be a sensitive marker of diastolic abnormality. The rise in E is paradoxical but has been seen in other studies. The increased blood flow velocity in the LV outflow tract suggests obstruction to LV outflow and increased flow in the descending aorta is due to residual coarctation.     

Noninvasive evaluation of systolic pressures of pulmonary artery and right ventricle using contrast-enhanced doppler echocardiography: Comparative study using sonicated albumin or glucose solution

Evaluation of pulmonary arterial pressure is essential for the diagnosis and management of patients with congenital heart disease; it is usually done by cardiac catheterization. An alternative, noninvasive method may be clinically more useful. The purpose of this study was to assess the usefulness of the noninvasive determination of systolic pressure of the pulmonary artery and right ventricle by contrast-enhanced Doppler echocardiography. We selected 30 pediatric patients (28 with trivial or nonsignificant tricuspid regurgitant Doppler signals and 2 with significant tricuspid regurgitant Doppler signals) aged 2 months to 21 years. The flow velocity of tricuspid regurgitation was measured with continuous-wave Doppler of the right ventricular inflow view or left parasternal or apical four-chamber view before and after injection of two types of contrast medium (hand-agitated 5% glucose or sonicated albumin). The systolic pressure of the pulmonary artery was assessed as the estimated right ventricular systolic pressure (albumin method) minus the peak pressure gradient across the pulmonary valve (nonenhanced Doppler method). After injection of hand-agitated 5% glucose and sonicated albumin, trivial tricuspid regurgitation signals were enhanced in 25 of 28 patients (89%). In two patients, spectral envelopes were well defined enough to obtain the peak systolic velocity of the tricuspid regurgitation jet without contrast medium injection. Peak velocity was not altered by injection of contrast medium in these patients. There was significant correlation between the estimation by contrast-enhanced Doppler using hand-agitated 5% glucose and the cardiac catheterization measurement of the transtricuspid pressure gradient (r= 0.88). The transtricuspid pressure gradients obtained by continuous-wave Doppler during sonicated albumin enhancement corresponded closely to those measured by cardiac catheterization (r = 0.95). Pulmonary arterial and right ventricular systolic pressures measured by Doppler using sonicated albumin and those obtained by cardiac catheterization were highly correlated (right ventricle, r = 0.96; pulmonary artery, r = 0.95). In conclusion, this technique may be a valuable noninvasive method for determining accurate right ventricular and pulmonary arterial systolic pressures.     

Exercise-Induced Hypertension After Corrective Surgery for Coarctation of the Aorta

The purpose of this investigation was to study exercise-induced hypertension after surgical repair of coarctation of the aorta (CoA). Groups of 27 patients with CoA and 27 healthy control subjects, 6–21 years old, were exercised to exhaustion using the Bruce protocol. Fourteen patients had undergone surgery during the first year of life (group A), and 13 patients had been operated on later (group B). The pulse rate and systolic blood pressures (BP) in the arm and leg were measured before, during, and after exercise to evaluate changes in the BP and the arm/leg BP gradient with exercise. The systolic BP was significantly higher in the patients than in the controls at all stages of the exercise test (p < 0.01), as was the arm/leg BP gradient both before and after exercise (p < 0.01); the latter increased significantly with exercise in the patient group (p < 0.05). We found hypertension to be a more common and severe problem in group B patients, who had higher blood pressures than their controls at rest and during exercise (p < 0.05). Exercise-induced hypertension was also more common in group B (23%) than in group A (7%). We conclude that exercise-induced hypertension and recoarctation are problems in postoperative CoA patients. Moreover, exercise-induced hypertension is more common in patients with CoA operated on after the first year of life.     

Ambulatory blood pressure in patients with occult recurrent coarctation of the aorta

The hypothesis that mild recurrent aortic obstruction produces subtle changes in ambulatory blood pressure was investigated by performing 24-hour monitoring on 11 postoperative coarctation patients. Patients (age 16.1±2.7 years) were compared with normal controls (age 15.7±2.5 years,n=15). Surgery (end-to-end anastomosis) was performed at 6.0±1.0 years of age. There were no significant differences between patients and controls in terms of baseline blood pressure (right arm 123/78±4/3 mmHg versus 120/75±3/2 mmHg) or right leg systolic pressure (125±6 mmHg versus 123±4 mmHg). Of the 11 patients 8 had recoarctation by Doppler study (mean gradient 25.3±2.1 mmHg), 5 of 11 had a postexercise arm-leg pressure difference of>30 mmHg, and 6 patients had aortic diameters at the site of surgery <70% of the descending aortic diameter (by magnetic resonance imaging). There were no significant differences between the coarctation and control groups in terms of mean ambulatory systolic (125±3 mmHg versus 119±2 mmHg) or diastolic (69±2 mmHg versus 72±2 mmHg) pressures throughout the day. However, coarctation patients had a larger number of systolic pressures that exceeded the 95th percentile (18.2±5.6% versus 6.8±1.2%). These labile increases in systolic pressure correlated with residual coarctation (r=0.642,p=0.003). Ambulatory monitoring is a useful tool for detecting and monitoring subtle abnormalities of blood pressure control after coarctation repair.     

Exercise Capacity in Young Patients After Total Repair of Tetralogy of Fallot

Tetralogy of Fallot is the most common form of cyanotic congenital heart disease. Measurement of physical activity is usually performed as a routine part of the patient's cardiac evaluation. The aim of this study was to examine the exercise performance of young patients operated on for tetralogy of Fallot, assessing the possible influence of known negative prognostic factors related to the surgical repair. The study group comprised 41 consecutive patients (29 male and 12 female, ages 11.2 ± 3.9 years, range 6–16 years) operated on for tetralogy of Fallot. Patients in the study group were divided in subgroups in relation to the age of surgical intervention (before or after 2 years of life), the surgical approach (combined transatrial/transpulmonary approach or right ventriculotomy), and the presence of aortopulmonary shunts prior to performing total correction. Their data were compared with those of 33 aged-matched asymptomatic control subjects (19 male and 14 female, ages 11.9 ± 1.3 years, range 11–16 years). Blood pressure and heart rate measured at rest were similar between control and Fallot groups. A normal increase in systolic blood pressure was observed in response to exercise intensity for all subgroups. No significant difference between control and Fallot groups was found under conditions of mild or moderate exercise or for diastolic blood pressure at rest and in response to exercise. Lower maximal heart rate and systolic blood pressure values were recorded in all patients when compared with the control subjects. Significant differences in peak workload were detected between control and Fallot groups and between the control and each subgroup; however, no difference was found between subgroups. In conclusion, despite their very satisfactory clinical status, all patients showed a reduced peak workload, irrespective of the surgical approach, age at surgery, and aortopulmonary shunts prior to performing total correction.     

Isoproterenol stress test during catheterization of patients with coarctation of the aorta

Background: The exercise test is considered useful in selecting high‐risk patients with repaired coarctation of the aorta (CoA), but it is difficult to obtain the cooperation of pediatric patients. The present study determines the feasibility of the isoproterenol stress test (IST) among pediatric patients with CoA. Methods: Thirteen patients with repaired or mild preoperative CoA aged 1–207 (median 13) months underwent 16 IST during cardiac catheterization. Peak‐to‐peak pressure gradients (PG) over the coarctation site were measured at baseline and at IST. Balloon angioplasty (BAP) was applied to patients with significant stenosis on angiography. Results: The PG between the ascending and the descending aorta was significantly higher at IST than at baseline (20.5 ± 11.5 vs 5.6 ± 3.9 mmHg, P < 0.0001). Heart rate, the systolic blood pressure measured at the ascending aorta, and pulse pressure were all significantly higher at IST than at baseline. The PG at IST decreased >10 mmHg in three of six patients after BAP. Conclusions: Significant pressure gradients over the coarctation site develop at IST in pediatric patients with repaired CoA or in preoperative patients with mild coarctation.     

Balloon Angioplasty of Native Coarctation of the Aorta in Infants and Neonates: Is It Worth the Hassle?

Balloon angioplasty (BA) for native coarctation of the aorta (CA) in infants and neonates remains controversial with a high incidence of restenosis. The purpose of this study is to analyze our acute and midterm results for BA of native CA in infants and neonates and try to identify factors that may be predictive of outcome. Between September 1991 and June 1999, 17 patients with CA underwent BA at a median age of 3 months (range 2 weeks–9 months) and median weight of 4.8 kg (range 2.8–7 kg). Fourteen patients had discrete CA and 3 had tubular hypoplasia. All patients were hemodynamically stable prior to BA and no patients had critical coarctation requiring prostaglandin E₁ infusion to maintain ductus arteriosus patency. Seven patients had other associated cardiac defects. All patients had significant initial improvement. The mean peak systolic gradient across the CA improved from 43 ± 15 mmHg to 10 ± 8 mmHg (p < 0.001), and the mean minimum diameter of the aortic lumen increased from 2.4 ± 0.9 mm to 5.2 ± 1.0 mm (p < 0.001). There was no mortality or major complication. At median follow-up interval of 2.7 years (0.15–7.75 years), 10 (59%) of 17 patients are clinically well and have an upper to lower limb systolic blood pressure difference of <20 mmHg. Seven (41%) of 17 patients developed significant restenosis (5 of these patients underwent repeat BA, which was successful in 3 patients). Four (24%) patients underwent surgical repair at a median age of 4.5 months (3–6.9 months) and a median time interval of 4 months (2–6.5 months) from the initial BA. All 3 patients with tubular hypoplasia type of CA underwent surgical repair. No patients developed aortic aneurysm following initial or repeat BA. All patients who underwent surgical repair were 1 month or less in age at the time of their initial BA. We conclude that BA of native CA in infants and neonates can be performed safely with low mortality and morbidity. It appears to offer the best results in patients who are older than 1 month with discrete CA and a well-developed aortic arch. Further restenosis of the discrete CA can be managed successfully by repeat BA.     

X-Chromosomal (p21) Muscular Dystrophy and Left Ventricular Diastolic and Systolic Function

In order to screen for cardiac abnormalities, we prospectively studied 15 patients (age 8–25 years, mean 15.5 years) with Duchenne's (DMD) (n= 9) and Becker's (BMD) (n= 6) muscular dystrophy using the echocardiogram. Data were compared to a control group of 92 healthy individuals (age 7.9–25 years, mean 14.3 years). Left ventricular filling in diastole showed a different pattern when comparing echocardiographic Doppler results in patients and controls: Patients had lower peak velocity of early left ventricular diastolic filling (E-vmax)(P < 0.0001) and smaller time velocity integral of the E-wave (E-tvi)(P < 0.0001). In contrast, the atrial component (A-vmax, A-tvi) of diastolic filling in DMD/BMD showed no significant difference to controls. The mean area of the mitral valve orifice was significantly larger in patients (P < 0.0001) without presence of mitral regurgitation. Systolic left ventricular function was significantly impaired in the DMD/BMD group; we found lower heart rate corrected fiber shortening velocity VCFc (P < 0.001) and higher peak systolic wall stress (P < 0.001) in DMD/BMD. In 8 of 15 patients, peak systolic wall stress was above 95th percentile of controls. In 6 of 15 patients, VCFc was lower than the 5th percentile of controls. Systolic and diastolic myocardial impairment was found even in young patients and at low stages of disability—equally among patients with DMD or BMD. Diastolic left ventricular impairment predominantly affected the early diastolic filling, but atrial compensation was poor. Peak systolic wall stress measurements were particularly useful in patients with CMP, reflecting the left ventricular afterload.     

Exercise testing after surgical repair of coarctation of the aorta

Summary After repair of coarctation, exercise testing was performed in 20 patients with an isolated coarctation (group I) and in 26 with additional congenital cardiac malformations (group II). Ages at time of operation were significantly different in both groups (7.9±6.0 years in group I; 4.6±3.8 years in group II;p≤0.01). Simultaneous blood pressures were obtained from upper and lower limbs at rest and after exercise. There was no significant difference regarding the systolic blood pressures at rest (122.5±15.6 mmHg in group I versus 119±15.8 mmHg in group II). Seven (14%) of the patients were hypertensive; five of them had blood pressure gradients between arms and legs of 15–45 mmHg. But the gradients at rest were found to be significantly different in both groups (9.0±10.5 mmHg in group I; 18.5±16.1 mmHg in group II;p≤0.05). Six patients, all in group II, had gradients ≥30 mmHg at rest. After exercise there were no significant differences in systolic blood pressure and gradients in both groups. Values for blood pressures and gradients at rest and after exercise showed a positive correlation (blood pressurer=0.76,p≤0.001; gradientr=0.44,p≤0.01). Thus exercise testing can provide valuable information about blood pressure and gradient changes during physical activity, but angiography is required to reveal restenosis or residual stenosis.     

Left Ventricular Diastolic Functions in Juvenile Rheumatoid Arthritis

Cardiac involvement as pericarditis, myocarditis, and endocarditis is common in juvenile rheumatoid arthritis (JRA). Though there are many reports concerning systolic and diastolic functions of adults with rheumatoid arthritis, there are no studies on children with JRA. Thirty patients with JRA without any cardiac symptoms and 30 sex- and age-matched controls were included in the study. M-mode and pulsed-wave Doppler echocardiography were performed on each participant to assess the systolic and diastolic functions of the left ventricle. Left ventricular end-systolic diameter and volume were larger and ejection fraction and fractional shortening were decreased in the JRA group. Among the diastolic parameters, increased late flow velocity, decreased early flow velocity, and prolonged isovolumic relaxation time reflected an abnormal relaxation form of diastolic dysfunction. Mortality rate is increased in adults with rheumatoid arthritis, and ischemic heart disease is the leading cause of cardiovascular mortality. The abnormal relaxation form of diastolic dysfunction found in children with JRA is seen in ischemic heart disease. These children can therefore be candidates for ischemic heart disease in the future even though they are fully asymptomatic at present. In conclusion, children with JRA should be assessed for systolic and diastolic functions with serial echocardiography. In this way it may be possible to reduce the mortality and morbidity of the disease from cardiac causes.     

Effects of low-dose dobutamine on left ventricular diastolic filling in children

To investigate the effects of dobutamine on the Doppler transmitral flow pattern in children with normal left ventricular function, Doppler echocardiography was used to measure the transmitral flow in 14 healthy children before and during infusion of dobutamine (5 μg/kg per minute). Cardiac output was measured by the thermodilution method, and stroke volume was calculated as the cardiac output divided by the heart rate. Dobutamine increased the peak velocity and flow velocity–time integral of early diastolic filling without changing those of atrial contraction and normalized peak velocity of early diastolic filling, suggesting an increase in left ventricular relaxation. Dobutamine increased the stroke volume and rate-corrected mean velocity of fiber shortening with reduced end-systolic wall stress, indicating an increase in left ventricular contractility. The percentage of increase in the flow velocity–time integral of early diastolic filling during dobutamine infusion tended to correlate with the increase in stroke volume (r= 0.67, p < 0.05) and with the decrease in end-systolic wall stress (r=−0.61, p < 0.05). Our results suggest that low-dose dobutamine increases left ventricular relaxation with enhanced systolic function. The observed decreased end-systolic wall stress might have caused enhanced relaxation characteristics with dobutamine.     

Exercise Tolerance and Blood Pressure Response to Exercise Testing in Children and Adolescents After Renal Transplantation

The aim of the study was to assess exercise tolerance and blood pressure (BP) response to treadmill exercise in children after renal transplantation. Forty-five children were selected (29 males and 16 females) whose mean age was 14.3 ± 4.2 years. All children had Hb ≥ 10 g/dl and creatinine clearance ≥40 ml/min/1.73 m². They were at least 6 months posttransplantation and were on triple immunosuppressive therapy. Twenty-seven were also on various antihypertensive medications. Each underwent clinical examination and measurement of BP, both at rest and during exercise testing on treadmill. The test was stopped on muscular fatigue or exhaustion. The patients were divided into two groups: those off (A) or on (B) antihypertensive therapy. When compared to a population of healthy children the patients had reduced exercise tolerance (10.1 ± 2.1 vs 15.1 ± 1.7 min, p < 0.001) (67 ± 16%), increased heart rate (174 ± 19 vs 161 ± 19 beats/min, p < 0.001) (109 ± 15%), and increased maximum systolic BP (150 ± 26 vs 134 ± 13 mmHg, p < 0.001) (113 ± 19%) at comparable workloads. Within the two patient groups, significant differences were observed during exercise testing for maximum heart rate, which was lower in group B (p= 0.03), and maximum systolic BP, which was higher in group A (p= 0.04). Our study confirms that children and adolescents on immunosuppressive therapy after renal transplantation have a hypertensive response during exercise, probably related to medication-induced peripheral vascular tone.     

Magnetic resonance imaging demonstration of “Remodeling” of the aorta following balloon angioplasty of discrete native coarctation

Assessment of the hemodynamic and anatomic results following balloon angioplasty of discrete native coarctation of the aorta, with particular attention to ``remodeling,' has required repeat cardiac catheterization and angiography, which is invasive and has limited resolution. Eight patients with hypertension and discrete native coarctation with an otherwise normally developed aortic arch underwent angioplasty at 5.0 ± 6.8 years of age. Angiographic cross-sectional areas of the aorta indexed to body surface area at the isthmus (I), coarctation site (C), and 1 cm distal to the coarctation site (Cd) pre- and postangioplasty were compared with MRI-indexed cross-sectional areas 18 ± 10 months (MRI-1) and 35 ± 11 months (MRI-2) postangioplasty. From preangioplasty to MRI-2, the isthmus was smaller (149 ± 22 versus 127 ± 27 mm<sup>2</sup>/m<sup>2</sup>; p < 0.05). The coarctation site was larger postangioplasty (25 ± 9 versus 116 ± 40 mm<sup>2</sup>/m<sup>2</sup>; p < 0.001) with continued growth at latest follow-up (116 ± 40 versus 164 ± 36 mm<sup>2</sup>/m<sup>2</sup>; p < 0.01). The segment 1 cm distal to the coarctation site continued to decrease in area at latest follow-up (267 ± 78 versus 163 ± 38 mm<sup>2</sup>/m<sup>2</sup>; p < 0.001). I versus C versus Cd at MRI-2 were similar, whereas postangioplasty and MRI-1 cross-sectional area measurements were significantly different. Following angioplasty of discrete native coarctation, the aorta becomes more uniform or undergoes ``remodeling.' Noninvasive MRI is an effective means of evaluating the anatomic result following balloon angioplasty, obviating the need for repeated invasive cardiac catheterizations.     

Doppler Flow Pattern and Arterial Stiffness in Patients with Aortic Coarctation

Patients with aortic coarctation (CoAo) often have a diastolic flow in the descending aorta. The effect of arterial stiffness on CoAo flow pattern was described in vitro and with computer models. Study of Doppler flow patterns and arterial stiffness may provide helpful data to support the decision of CoAo treatment. Fifty studies were obtained in 31 patients (14 women, 21.5 ± 15.5 years). In 19 patients, studies were performed before and after percutaneous intervention. Systolic invasive gradients were measured (Sgrad). Doppler parameters included Doppler corrected gradient (Dgrad), diastolic velocity at end of T wave (DVT), end diastolic velocity (DVQ), systolic and diastolic half pressure times (SHPTc and DHPTc) and velocity runoff (VRc). In 19 patients, before intervention, arterial stiffness was assessed by measuring pulsed wave velocity (PWV) between right carotid and radial arteries. Sgrad showed correlation with Dgrad, DVT, DVQ, SHPTc, DHPTc and VRc (p < 0.01). Using multiple regression models, Sgrad variability was best explained by combining the variables Dgrad and DHPTc (R ² = 0.766). A variable named DTail was obtained with DTail = 1 if DHPTc > 0. In the group with Sgrad below 30 mmHg, a negative correlation was found between DTail and PWV (p = 0.024), suggesting that low aortic stiffness contributes to persistent diastolic flow in the descending aorta. Doppler systolic and diastolic parameters correlated well with severity of CoAo. In mild to moderate CoAo, Doppler diastolic flow in the descending aorta was more likely in patients with lower arterial stiffness.     

Left Ventricular Diastolic Filling Patterns Associated with Progressive Anthracycline-Induced Myocardial Damage: A Prospective Study

The objective of this study was to examine changes in diastolic function associated with progressive myocardial damage and their implications. We used prospective sequential Doppler echocardiographic studies of left ventricular (LV) function. The study included 125 consecutive children (median age 6.3 years) receiving anthracyclines to cumulative doses between 45 and 1150 mg/m² (median 270 mg/m²). We measured peak early (E) and atrial (A) phase filling velocities, EA ratio, deceleration and isovolumic relaxation times (EDecT and IVRT), heart rate, and fractional shortening (SF). Results were compared serially and with individually paired control data matched for body surface area. Progressive myocardial damage was evidenced by a mean SF decrease of 1 absolute %/100 mg/m² of anthracycline. Six patients developed cardiac failure. After 1–100 mg/m² of anthracyclines, the EA ratio decreased (mean 1.54–1.40, p= 0.02) and IVRT became prolonged (54 vs 52 msec in controls, p= 0.03). EA ratio increased again with the next dose, usually normalizing thereafter. Twelve patients ended treatment with an EA ratio <1 (1 cardiac death) and 17 with EA ratio >2 (2 cardiac deaths). Diastolic abnormalities were not strongly predictive of reduced SF. Modest changes in left ventricular diastolic filling patterns occur during anthracycline treatment of childhood malignancies. Although 20% of patients have significant abnormalities of diastolic filling by the end of treatment, considerable individual variability renders the pathophysiological and clinical implications of the early changes uncertain.     

Factors Affecting the Exercise Capacity of Pediatric Patients with Aortic Regurgitation

Although exercise testing is commonly employed to identify adult aortic regurgitation (AR) patients with early left ventricular (LV) dysfunction, the role and value of exercise testing in the management of pediatric AR patients have not been established. The purposes of this study were to evaluate the cardiorespiratory response to exercise of pediatric patients with chronic AR, examine the relation between exercise function and baseline echocardiographic measurements, and identify factors related to diminished exercise capacity (EC). The study group consisted of 26 patients aged 8 to 21 years (mean 14.4 ± 3.7) with moderate or severe AR referred for exercise physiology testing. All patients underwent a baseline echocardiographic study and a symptom-limited, progressive cycle ergometer exercise test. LV diastolic dimension averaged 120 ± 12% predicted, systolic dimension 112 ± 20% predicted, shortening fraction 0.41 ± 0.07, end-systolic wall stress 65 ± 23 g/cm², and regurgitant fraction 38 ± 16%. The average EC was 88 ± 28% (56–143) predicted. No statistically significant correlation was found between EC and any of the echocardiographic parameters studied. Nine patients had EC < 75% predicted. These individuals did not differ from patients with higher EC with regard to any of the echocardiographic parameters or with regard to peak heart rate, blood pressure, respiratory exchange ratio, and incidence of ectopy or ST depression. However, the oxygen pulse at peak exercise (an index proportional to forward stroke volume at peak exercise) was significantly depressed among patients with EC < 75% predicted (77 ± 6 vs. 106 ± 16% predicted, p < .0001). In conclusion, most pediatric patients with moderate or severe AR compensate well for their valve disease, maintain normal forward stroke volume during exercise, and have normal EC. However, a subset of AR patients have diminished EC secondary to an inability to augment forward stroke volume appropriately. These patients cannot be identified on the basis of resting echocardiographic studies. Timely identification of these patients, through formal exercise physiology testing, may have important clinical implications.     

Evaluation of Magnetic Resonance Imaging in Coarctation of the Aorta: The Importance of Multiple Imaging Planes

Coarctation of the aorta can be evaluated reliably and noninvasively by magnetic resonance imaging. However, the value of different imaging planes in the evaluation of restenosis or aneurysm has not previously been studied. Our purpose was to study the relative sensitivity for oblique coronal and oblique parasagittal magnetic resonance imaging to detect restenosis or aneurysm formation in children following surgical repair or balloon angioplasty of coarctation of the aorta. The study included magnetic resonance imaging studies in 27 children. Each exam included ECG gated, spin-echo imaging in oblique coronal and oblique parasagittal planes. Recoarctation was defined as a greater than 50% narrowing of the aorta. Aneurysms were defined as focal dilatation of the aorta in the region of coarctation 20% or greater than the adjacent aortic diameter. Recoarctation was detected in 11 children, but in both views in only five children. Aneurysms were detected in 15 children, but in both views in only three children. Recoarctation and aneurysm detection were both statistically more likely to be detected if oblique coronal and oblique parasagittal views were obtained, indicating that multiple imaging planes are necessary to completely evaluate magnetic resonance imaging of coarctation.     

Plasma Concentrations of Atrial and Brain Natriuretic Peptides and Cyclic Guanosine Monophosphate in Response to Dobutamine Infusion in Patients with Surgically Repaired Tetralogy of Fallot

We examined the plasma concentrations of atrial and brain natriuretic peptides (ANP and BNP) and cyclic guanosine monophosphate (cGMP) during dobutamine infusion and their relationship with hemodynamic parameters in 14 patients with surgically repaired tetralogy of Fallot (TOF). Dobutamine was infused at an initial dose of 5 μg/kg/min and increased by 5 μg/kg/min up to 20 μg/kg/min. The plasma ANP, BNP, and cGMP concentrations were determined before infusion, at the end of each stage, and 15 minutes after discontinuing dobutamine infusion. The plasma concentrations of ANP, BNP, and cGMP were elevated in all patients before dobutamine infusion. The ANP, BNP, and cGMP concentrations decreased in 11 of the 14 patients during dobutamine infusion. In contrast, the plasma ANP and BNP concentrations increased in the remaining 3 patients without a change in the cGMP concentration. The right ventricular pressure and volume were significantly elevated in these patients. The plasma cGMP concentration correlated with the ANP concentration (r= 0.62, p < 0.01) but not the BNP concentration. The plasma ANP concentration during dobutamine infusion correlated with right ventricular systolic pressure (r= 0.71, p < 0.05), mean right atrial pressure (r= 0.29, p < 0.05), and mean pulmonary capillary wedge pressure (r= 0.32, p < 0.05). The BNP concentration correlated with right ventricular volume (r= 0.61, p < 0.05) and systolic pressure (r= 0.46, p < 0.05). In conclusion, rapid changes in ANP, BNP, and cGMP concentrations during dobutamine infusion reflect the changes in atrial and ventricle pressure and volume overload. In surgically repaired TOF, the ANP concentration is affected by right ventricular systolic pressure, right atrial pressure, and pulmonary capillary pressure. Furthermore, the BNP concentration reflects right ventricular pressure and volume overload.     

Acute loads applied to the right ventricle: Effect on left ventricular filling dynamics in the presence of an open pericardium

To determine whether diastolic ventricular interdependence mechanisms would act in the presence of an open pericardial sac, as during cardiac surgery, moderate acute right ventricle afterload increases were applied to eight dogs with the chest and pericardium open while left ventricular filling dynamics were being assessed by Doppler echocardiography. Dogs were studied under basal conditions and after acute banding of the main pulmonary artery tightened to produce a 100% increase in right ventricular systolic pressure. With banding, the left ventricular filling velocity ratio (E/A), as assessed by Doppler echocardiography of mitral inflow, changed from a baseline value of 1.32 ± 0.05 to 1.16 ± 0.03 (p < 0.02), suggesting a restrictive pattern to early left ventricular filling, which is differed to that during the second half of diastole. Isovolumic relaxation time, measured as the time interval between aortic valve closure and mitral valve opening, assessed by M-mode echocardiography of both valves, was prolonged, though not significantly, from 63.3 ± 2.5 ms to 69.4 ± 2.9 ms, by banding of the pulmonary artery. E wave deceleration time, a filling variable influenced by chamber pressure/volume relations, was shortened by pulmonary artery banding, changing from 75.1 ± 1.7 ms to 68.0 ± 1.8 ms (p < 0.01). It was concluded that pressure loads applied to the right ventricle restricted early left ventricular filling. Prolonged relaxation and altered pressure–volume chamber relations were the diastolic interdependence mechanisms involved that proved to be acting even under open pericardium conditions.