Persistent ventricular adaptations in postoperative coarctation of the aorta

Hemodynamic Changes During Physiological and Pharmacological Stress Testing in Healthy Subjects, Aortic Stenosis and Aortic Coarctation Patients-A Systematic Review and Meta-Analysis

Introduction: Exercise testing has become a diagnostic standard in the evaluation and management of heart disease. While different methods of exercise and pharmacological stress testing exist, only little is known about their comparability. We aimed to assess hemodynamic changes during dynamic exercise, isometric exercise, and dobutamine stress testing at different stress intensities in healthy subjects and patients with aortic stenosis (AS) and aortic coarctation (CoA).

Methods: A systematic literature search (PROSPERO 2017:CRD42017078608) in MEDLINE of interventional trials was conducted to identify eligible studies providing evidence of changes in hemodynamic parameters under different stress conditions acquired by MRI or echocardiography. A random effects model was used to estimate pooled mean changes in hemodynamics.

Results: One hundred and twenty-eight study arms with a total of 3,139 stress-examinations were included. In healthy subjects/(where available) in AS, pooled mean changes (95% CIs) during light dynamic stress were 31.78 (27.82–35.74) bpm in heart rate (HR) and 6.59 (2.58–10.61) ml in stroke volume (SV). Changes during light pharmacological stress were 13.71 (7.87–19.56)/14.0 (9.82–18.18) bpm in HR, and 5.47 (0.3–10.63)/8.0 (3.82–12.18) ml in SV. Changes during light isometric stress were 18.44 (10.74–26.14)/5.0 (−1.17–11.17) bpm in HR and −4.17 (−14.37–6.03)/−4.0 (−16.43–8.43) ml in SV. Changes during moderate dynamic stress were 49.57 (40.03–59.1)/46.45 (42.63–50.27) bpm in HR and 11.64 (5.87–17.42) ml in SV. During moderate pharmacological stress, changes in HR were 42.83 (36.94–48.72)/18.66 (2.38–34.93) bpm and in SV 6.29 (−2.0–14.58)/13.11 (7.99–18.23) ml. During high intensity dynamic stress changes in HR were 89.31 (81.46–97.17)/55.32 (47.31–63.33) bpm and in SV 21.31 (13.42–29.21)/−0.96 (−5.27–3.35) ml. During high pharmacological stress, changes in HR were 53.58 (36.53–70.64)/42.52 (32.77–52.28) bpm, and in SV 0.98 (−9.32–11.27)/14.06 (−1.62–29.74) ml. HR increase and age were inversely correlated at high stress intensities. In CoA, evidence was limited to single studies.

Conclusion: This systematic review and meta-analysis presents pooled hemodynamic changes under light, moderate and high intensity exercise and pharmacological stress, while considering the potential influence of age. Despite limited availability of comparative studies, the reference values presented in this review allow estimation of the expected individual range of a circulatory response in healthy individuals and patients with AS and may contribute to future study planning and patient-specific models even when stress testing is contraindicated.

Impact of Transcatheter Intervention on Myocardial Deformation in Patients with Coarctation of the Aorta

Myocardial deformation measured by speckle tracking echocardiography can detect subtle abnormalities of left ventricular function before an obvious abnormality in traditional echocardiographic parameters such as ejection fraction is seen. We hypothesized that patients with coarctation of the aorta (CoA) may have impaired myocardial deformation that may persist even after successful transcatheter intervention. This is a retrospective study to assess the myocardial deformation in patients undergoing transcatheter intervention of CoA. The data were compared with age-matched normal controls. Echocardiographic parameters were obtained before, immediately and at median 6 months (range 3-8 months) after transcatheter intervention. Myocardial deformation indices were obtained off-line using Tomtec 2D Cardiac Performance Analysis Software. Repeated measure ANOVA was used to compare the indices between three time points. Independent sample t test or Chi-square test was used to compare data between groups. Twenty-four patients (age 13.5 ± 7.7 years) underwent successful transcatheter CoA intervention (stent 19, balloon angioplasty five) improving CoA peak gradient in the catheterization laboratory from 27.1 ± 11.3 to 4.5 ± 3.0 mmHg (p < 0.001). To compare with normal controls (n = 25, age 14.5 ± 1.9 years), fraction shortening was significantly higher in pre-intervention CoA patients (40.4 ± 7.1 vs. 33.8 ± 2.4 %, p < 0.001). In contrast, CoA patients had significantly abnormal left ventricular longitudinal strain compared to normal controls (-14.9 ± 2.6 vs. -20.5 ± 1.8 %, p < 0.001). In CoA patients, left ventricular longitudinal strain improved immediately and 3-8 months after intervention (-18.0 ± 2.9 and -17.6 ± 2.9 %, p < 0.007) but continued to be abnormal compared to normal controls. Patients with CoA had impaired myocardial deformation compared to normal controls. Myocardial mechanics improved but did not normalize even after successful transcatheter intervention on CoA in the short term.

Left ventricular response to pressure afterload in children: aortic stenosis and coarctation: a systematic review of the current evidence

Congenital aortic stenosis (CAS) and Coarctation of Aorta (CoA) represent two forms of pressure afterload that affect the left ventricle (LV), hence require regular echocardiographic monitoring. Subclinical dysfunction of the LV exists even in asymptomatic patients with preserved left ventricular ejection fraction (EF), implying low sensitivity of EF in predicting optimum time for intervention. In this article we review patterns of LV myocardial deformation before and after correction of CAS and CoA in infants, children and adolescents, showing their important role in monitoring the course of LV dysfunction. A systematic search using PubMed was performed and suitable studies are presented on a narrative form. Normal EF and/or fractional shortening (FS), with subclinical myocardial dysfunction are reported in all studies before intervention. The short-term results, after intervention, were related to the type of procedure, with no improvement or further deterioration related to surgery but immediate improvement after balloon intervention. Long term follow-up showed further improvement but still subnormal function. Thus correction of CAS and CoA before irreversible LV dysfunction is vital, and requires longitudinal studies in order to identify the most accurate parameter for function prognostication. Until then, conventional echocardiographic parameters together with myocardial velocities and deformation parameters should continue to provide follow-up reproducible measures of ventricular function.

Regional left ventricular myocardial shortening in normotensive patients late after aortic coarctation repair - normal or impaired?

Despite successful repair of aortic coarctation (AoC), changes in the left ventricular (LV) regional myocardial function are reported. The aims of this study were (i) to determine LV regional longitudinal deformation in patients who underwent a repair of AoC, who were normotensive and who had normal LV global function; and (ii) to establish a potential correlation between the degree of residual narrowing in the descending aorta and the extent of LV regional deformation. We studied 22 normotensive patients aged 19-58 y (mean 32.6; SD+/-11.3). Maximal strain, epsilon (%), as well as peak systolic and early and late diastolic strain rates (SRs; s(-1)), were obtained on the basis of speckle tracking. The data were compared with those obtained from sex and age-matched controls. Regional SRs were significantly reduced for the LV anterior wall during systole and early diastole -1.1 vs. -1.39; 1.41 vs. 1.86 s(-1), respectively; p<0.05. Transaortic maximal and mean gradients across the coarctation site correlated with epsilon and systolic SR obtained from the midsegment of the LV anterior wall. Despite a successful repair, absence of systemic hypertension and normal global LV function, regional deformation properties of the anterior LV wall were impaired. The degree of longitudinal impairment in this anatomical region correlated with the extent of residual narrowing.

Abnormal regional myocardial deformation properties and increased aortic stiffness in normotensive patients with aortic coarctation despite successful correction: an ABPM, standard echocardiography and strain rate imaging study

The long-term follow-up data subsequent to a successful repair of AoC (aortic coarctation) show that life expectancy remains reduced. Previous standard echocardiographic studies have demonstrated normal or increased systolic cardiac function in patients following successful repair of AoC. SR (strain rate) imaging is a new technique able to detect subclinical myocardial abnormalities. In the present study we investigated whether young patients (without hypertension, as assessed using ambulatory blood pressure monitoring and an exercise test) following successful AoC repair already have abnormal myocardial deformation properties, and the relationship of the deformation properties with aortic stiffness. We studied 166 subjects, 83 AoC non-hypertensive patients (mean age 12+/-4 years) a number of years after successful repair of AoC and 83 age- and sex-matched subjects as controls. Peak systolic SR (1/s) for both regional longitudinal and radial function was assessed. The aortic stiffness index was calculated from the echocardiographically derived thoracic aortic diameters, and the measurement of blood pressure was obtained by cuff sphygmomanometry. The LV (left ventricular) ejection fraction was significantly increased in AoC patients, whereas regional longitudinal SRs were significantly reduced (-1.1+/-0.9 compared with -2+/-0.5, P<0.0001) in patients. The aortic stiffness index was significantly increased in AoC patients (12+/-9, P<0.0001). At multilinear regression analysis, age at repair (P=0.005; coefficient, -0.201; S.E.M., 0.027) and the aortic stiffness index (P=0.0029; coefficient, 0.334; S.E.M., 0.423) predicted longitudinal SR. Despite the presence of a successful repair for AoC, in the absence of hypertension, longitudinal deformation properties were significantly impaired. Moreover, the degree of longitudinal SR impairment was correlated with age at repair and aortic stiffness. Early repair can delay the onset of hypertension in postcoarctectomy patients, but cannot prevent the innate structural and functional abnormalities of the aorta and their deleterious effect on myocardial deformation properties.

Factors affecting left ventricular remodelling and mechanics in the long-term follow-up after successful repair of aortic coarctation

AIMS

To identify factors predisposing to abnormal left ventricular geometry and mechanics in 52 patients after successful repair of aortic coarctation.

METHODS AND RESULTS

We evaluated left ventricular remodelling, systolic midwall mechanics, and isthmic gradient by echo-Doppler, systemic blood pressure at rest/exercise and by ambulatory blood pressure monitoring, and the aortic arch by magnetic resonance imaging. Echocardiographic findings were compared with those of 142 controls. The patients with aortic coarctation showed an increased indexed left ventricular end-diastolic volume, increased mass index, increased ratio of mass to volume and systolic chamber function. The contractility, estimated at midwall level, was increased in 21 percent of the patients. In 26 (50 percent) of the patients, we found abnormal left ventricular geometry, with 9 percent showing concentric remodelling, 33 percent eccentric hypertrophy, and 8 percent concentric hypertrophy. These patients were found to be older, underwent a later surgical repair, and to have higher systolic blood pressures at rest and exercise as well as during ambulatory monitoring. The relative mural thickness and mass index of the left ventricle showed a significant correlation with different variables on uni- and multivariate analysis. Age and diastolic blood pressure at rest are the only factors associated with abnormal left ventricular remodelling.

CONCLUSIONS

Patients who have undergone a seemingly successful surgical repair of aortic coarctation may have persistently abnormal geometry with a hyperdynamic state of the left ventricle. This is more frequent in older patients, and in those with higher diastolic blood pressures.

Relation between exercise-induced hypertension and sustained hypertension in adult patients after successful repair of aortic coarctation

OBJECTIVES

To investigate whether exercise-induced hypertension in successfully repaired adult post-coarctectomy patients is associated with hypertension on 24-h blood pressure measurement and increased left ventricular mass.

METHODS

One hundred and forty-four consecutive post-coarctectomy patients (mean age 31.5 years, range 17-74 years; mean age at repair 7.9 years, range 0-45 years) from three tertiary referral centres were studied using ambulatory blood pressure monitoring, treadmill exercise testing and echocardiography.

RESULTS

Of the 144 patients, 27 (19%) were known to have sustained hypertension, based on their history, and all were on antihypertensive medication. However, 32 (27%) of the remaining 117 patients showed elevated mean daytime systolic blood pressure readings at 24-h ambulatory blood pressure monitoring (systolic blood pressure > or = 140 mmHg). Of the remaining 85 patients with normal mean daytime systolic blood pressure, 18 patients (21%) had exercise-induced hypertension (maximal exercise systolic blood pressure > 200 mmHg). Mean daytime systolic blood pressure was higher in the exercise-induced hypertensive patients compared to the normotensive patients with normal exercise blood pressure (134 +/- 5 versus 129 +/- 7 mmHg, P = 0.008). By multivariate analysis, both maximal exercise systolic blood pressure (P = 0.007) and resting systolic blood pressure (P < 0.0001) were independently associated with mean daytime systolic blood pressure. Maximal exercise systolic blood pressure had no independent predictive value for left ventricular mass (P = 0.132).

CONCLUSIONS

In adult post-coarctectomy patients, maximal exercise systolic blood pressure is independently associated with mean daytime systolic blood pressure at ambulatory blood pressure monitoring. In this study no independent predictive value of maximal exercise systolic blood pressure for left ventricular mass could be demonstrated.

Left ventricular remodeling and mechanics after successful repair of aortic coarctation

Forty normotensive patients (mean age 12.3 +/- 6.5 years) followed up after a successful repair of aortic coarctation (mean age at coarctectomy 5.1 +/- 4.8 yrs) were studied by echo-Doppler to (1) evaluate left ventricular (LV) remodeling and endocardial and midwall mechanics, and (2) identify factors that might predispose to persistent abnormalities. Sex- and age-specific cutoff levels for LV mass/height2.7 and relative wall thickness were defined to assess LV geometry. To adjust for age-and growth-related changes in ventricular mechanics, all echocardiographic variables were expressed as a Z-score relative to the normal distribution. In addition, the smallest diameter of the aorta was assessed by magnetic resonance imaging and calculated as percent narrowing compared with the diameter of the aorta at the diaphragmatic level. In the study group, 24 of 40 patients (60%) had normal LV geometry. Among the 16 patients (40%) with abnormal LV geometry, 5 (12.5%) had a pattern of concentric remodeling and 11 (27.5%) an eccentric hypertrophy. LV hypertrophy was marked (LV mass index >51 g/m2.7) in 5 of these patients. No patient had a pattern of concentric hypertrophy. LV contractility was increased (Z-score >95th percentile) in 28 patients (70%) as assessed using the endocardial stress-velocity index. In contrast, LV contractility assessed using midwall stress-velocity index remained elevated (Z-score >95th percentile) in 15 patients (37.5%). The stepwise multiple logistic regression analysis was not able to detect any significant independent predictor of abnormal LV remodeling, including sex, age at surgical repair, length of postoperative follow-up, heart rate, body mass index, systolic and diastolic blood pressure, and smallest diameter of the aorta, as well as indexes of LV geometry (shape, mass, volume, mass/ volume ratio) and function (preload, afterload, pump function, and myocardial contractility). Thus, normotensive patients after surgical repair of aortic coarctation may be in an LV hyperdynamic cardiovascular state (more frequent in those who have undergone late repair) and have multiple patterns of LV geometry.

Resetting of the cardiopulmonary baroreflex 10 years after surgical repair of coarctation of the aorta

OBJECTIVE

To characterise cardiopulmonary baroreflex responses and examine the effects of a 45 minute cycling bout late after successful repair of coarctation of the aorta.

SUBJECTS

10 young adults (mean (SEM) age 18.1 (2.6 years)) operated on for coarctation of the aorta 12.7 (3.5) years earlier, and 10 healthy controls.

DESIGN

Forearm blood flow (venous occlusion plethysmography) and vascular resistance, left ventricular internal diastolic diameter, and central venous pressure estimated from an antecubital vein were measured in the supine position at baseline and during five minute applications of lower body negative pressure (LBNP) at -15 mm Hg (LBNP(-15)) and -40 mm Hg (LBNP(-40)). Venous samples were obtained at baseline and during LBNP(-40) for noradrenaline (norepinephrine), adrenaline (epinephrine), renin activity, and aldosterone. The tests were repeated after 45 minutes of moderate exercise.

RESULTS

Baseline heart rate (78 (9) v 64 (6) beats/min), echocardiographic cardiac output (6.9 (1.1) v 5.0 (0.2) l/min), shortening fraction (41.7 (1.8)% v 33.3 (1.3)%), and forearm blood flow (3.4 (0.4) v 2.3 (0.3) ml/100 g/min) were higher in the coarctation group than in the controls (p < 0.05). Changes in forearm blood flow and forearm vascular resistance from baseline to LBNP(-40) were similar in both groups, but the relation between forearm vascular resistance and estimated central venous pressure or left ventricular internal diastolic diameter was shifted downward in the coarctation group. Plasma adrenaline was increased in the coarctation group (baseline: 3.2 (0.6) v 2.4 (0.3) pmol/l in controls; LBNP(-40): 687 (151) v 332 (42) pmol/l) (p < 0.05). Both groups showed a similar downward displacement of forearm vascular resistance (p < 0.05) after exercise.

CONCLUSIONS

There appears to be resetting of the cardiopulmonary baroreflex to a lower forearm vascular resistance in young adults operated on for coarctation of the aorta, associated with hyperdynamic left ventricular function. Raised circulating adrenaline could contribute to the lower forearm vascular resistance.

A population-based prospective evaluation of risk of sudden cardiac death after operation for common congenital heart defects

OBJECTIVES

This study sought to define 1) the risk of sudden death after operation for common congenital heart defects; and 2) factors associated with an increased risk of sudden death.

BACKGROUND

Although the prognosis for patients with congenital heart defects is improved by surgical treatment, they remain at a well recognized but poorly defined risk of late sudden death.

METHODS

This population-based study evaluated all patients < 19 years old undergoing surgical treatment of common forms of congenital heart disease in the state of Oregon between 1958 and 1996. Patients were identified retrospectively through 1958, with prospective biannual follow-up beginning in 1982. The incidence and cause of late sudden death were evaluated for 3,589 patients surviving operation for the following defects: atrial, ventricular and atrioventricular septal defects; patent ductus arteriosus; pulmonary stenosis; aortic stenosis; coarctation of the aorta; tetralogy of Fallot; and D-transposition of the great arteries.

RESULTS

There were 41 unexpected late sudden deaths during 45,857 patient-years of follow-up, an overall event rate of 1/1,118 patient-years. Thirty-seven of the 41 late sudden deaths occurred in patients with aortic stenosis, coarctation, transposition of the great arteries or tetralogy of Fallot, an event rate of 1/454 patients-years. In contrast, only four sudden deaths occurred among the other defects, an event rate of 1/7,154 patient-years (p < 0.01). The risk of late sudden death increased incrementally 20 years after operation for tetralogy of Fallot, aortic stenosis and coarctation. However, risk was not dependent on patient age at operation or surgical era. The causes of sudden death were arrhythmia in 30 patients, circulatory (embolic or aneurysm rupture) in 7 and acute heart failure in 4.

CONCLUSIONS

The risk of late sudden death for patients surviving operation for common congenital heart defects is 25 to 100 times greater than an age-matched control population. This increased risk is primarily represented by patients with cyanotic or left heart obstructive lesions. The risk of sudden death appears to be time dependent, increasing primarily after the second postoperative decade.

Total simultaneous repair of coarctation and intracardiac pathology in adult patients

BACKGROUND

Thoracic aortic coarctation accompanied by a second surgically reparable lesion is a rare combination in the adult patient. The simultaneous operative management of both lesions is desirable because of the higher morbidity and mortality that would occur with staged procedures.

METHODS

We describe the simultaneous operative management in three adult patients with coarctation and a second cardiac lesion. All 3 patients had intrapericardial ascending aorta-descending aorta bypass and concomitant repair of a cardiac lesion. The attendant repairs in the 3 patients, respectively, were aortic valve replacement, orthotopic heart transplantation, and coronary artery bypass grafting.

RESULTS

Double arterial cannulation, retrograde cardioplegia, large-bore aorto-aortic bypass grafts, and early use of alpha-agonists to stabilize systemic pressure were all key to ensuring safe conduct of the operation. Each patient had an essentially uneventful postoperative course.

CONCLUSIONS

Thoracic coarctation and concomitant cardiac pathology can be safely and readily managed with a single-stage approach involving cardiac repair and extraanatomic ascending aorta-descending aorta bypass grafting. A review of the English-language literature of patients managed similarly is included.

Peripheral blood flow responses to exercise after successful correction of coarctation of the aorta

OBJECTIVES

The purpose of this study was to characterize peripheral flow kinetics in response to progressive discontinuous maximal exercise in 10 patients who underwent repair of coarctation of the aorta and 11 age-matched healthy adolescents.

BACKGROUND

An impairment of leg blood flow has been suggested on the basis of exaggerated femoral muscle lactate accumulation in patients with successful repair of coarctation. Few data are available describing blood flow kinetics of the exercising leg in such patients.

METHODS

Duplex ultrasound provided transcutaneous measurements of peak systolic and end-diastolic flow velocities of the femoral, humeral and renal arteries at rest and immediately after mild, moderate and maximal exercise intensities for computation of mean velocity, resistance index and femoral blood flow.

RESULTS

Femoral mean velocity and femoral blood flow increased linearly with exercise intensity in both groups, but the slope of this increase was significantly lower in patients. Similarly, humeral mean velocity increased significantly less in patients than in control subjects. Femoral resistance index sharply decreased from that at rest (patients [mean +/- SE] 1.4 +/- 0.04; control subjects 1.4 +/- 0.03) to mild exercise intensity in both groups (patients 0.69 +/- 0.03; control subjects 0.72 +/- 0.03). A further decrease was observed at maximal exercise in patients (0.60 +/- 0.04, p = 0.08) but not in control subjects (0.69 +/- 0.02).

CONCLUSIONS

These observations suggest that despite a greater exercise-induced femoral vasodilation, patients with successful correction of coarctation of the aorta demonstrate an impaired lower limb blood flow in response to strenuous dynamic exercise. In the absence of stenosis at rest, this alteration could result from exaggerated flow turbulence in the descending aorta distal to the site of correction because of loss of elasticity at the site of the resection of the coarcted segment.

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.

Persistent hyperdynamic cardiovascular state at rest and during exercise in children after successful repair of coarctation of the aorta

OBJECTIVES

The purposes of this study were to evaluate left ventricular performance and contractility at rest and during exercise to determine mechanisms and correlates for alterations in performance and blood pressure in pediatric patients after successful repair of coarctation of the aorta.

BACKGROUND

Blood pressure and left ventricular function are elevated in children despite successful repair. The mechanisms for these changes are not understood.

METHODS

Thirty asymptomatic pediatric patients with successful coarctation repair (mean age [+/- SD] 12.5 +/- 4 years) underwent echocardiographic determination of left ventricular mass, performance (shortening fraction), preload (indexed diastolic dimension), afterload (end-systolic wall stress), contractility (velocity of circumferential fiber shortening/wall stress relation) and Doppler gradient at rest and during exercise. Data were compared with those of 24 control subjects (mean age 21.0 +- 4 years). Because of the age discrepancy between groups, age-dependent echocardiographic data were indexed by body surface area.

RESULTS

The mean age at operation was 5 +/- 4 years, and the average follow-up period was 7.5 +/- 3 years. The average blood pressure gradient between upper and lower limbs was 4 mm Hg. Left ventricular mass was higher in the postoperative group than in the control group (1.58 vs. 1.31 g/ht2.7, p = 0.04), as were values at rest for performance (44% vs. 31%, p = 0.0001), preload (3.9 vs. 3.7 cm/body surface area0.5), indexes systolic blood pressure (1.05 vs. 0.91, p = 0.0001) and contractility (0.23 vs. -0.05 circumferences/s, p= 0.001). Afterload was lower at rest (36 vs. 52 g/cm2, p = 0.0004). These differences between groups persisted during and after exercise. Contractility underwent an exaggerated increase after exercise in the postoperative group.

CONCLUSIONS

Left ventricular performance in children after coarctation repair is higher at rest and during exercise than in control subjects as a result of higher preload and contractility and lower afterload. These changes may be due to associated hypertrophy. Persistent postoperative hypertension may be due to a hyperdynamic, hypercontractile state caused by residual gradients manifested only during exertion.

Comparison of ventricular mass and function in early versus late repair of coarctation of the aorta

Left ventricular (LV) mass and function in 11 patients (group I) with coarctation of the aorta repaired at a mean age of 35 days were compared with that of 14 patients (group II) who underwent repair at a mean age of 8 years. Each group was compared to age- and sex-matched normal control subjects. All patients were normotensive and had resting arm-leg peak systolic blood pressure gradients < 20 mm Hg. Quantitative M-mode echocardiography was used to determine LV mass index and systolic performance. Magnetic resonance imaging was performed to assess residual narrowing of the descending aorta. LV mass index was increased in both groups when compared with control subjects (group I p = 0.01; group II p = 0.007). Whereas systolic performance in group I was similar to its control group, group II patients had enhanced LV systolic performance as measured by shortening fraction (p = 0.007). Multiple regression analysis of combined group I and II patients demonstrated a significant positive correlation of residual aortic narrowing with LV mass index (p = 0.01). Thus, LV mass remains increased in normotensive patients without major blood pressure gradients after repair of coarctation of the aorta in infancy or childhood. Small degrees of residual aortic narrowing were associated with increased postoperative LV mass regardless of the age at repair.

Left ventricular diastolic dysfunction late after coarctation repair in childhood: influence of left ventricular hypertrophy

OBJECTIVES

Left ventricular systolic and diastolic function were evaluated late after successful operation for aortic coarctation in childhood.

BACKGROUND

Persistent arterial hypertension and left ventricular hypertrophy after coarctation repair might impair left ventricular function.

METHODS

Biplane angiography and simultaneous high fidelity pressure measurements were performed in 12 patients 3 to 12 years postoperatively (residual pressure gradient 4 mm Hg). Eight patients were normotensive and four had borderline hypertension. Data at rest and after nitroprusside infusion (1.7 micrograms/kg per min) were evaluated and compared with data from 12 control subjects.

RESULTS

Systolic left ventricular function (ejection fraction-end-systolic wall stress relation) was normal in all patients. However, left ventricular muscle mass (113 vs. 86 g/m2), right atrial pressure (5.2 vs. 1.9 mm Hg) and left ventricular end-diastolic pressure (16 vs. 11 mm Hg) were significantly higher in patients than in control subjects. There was a linear relation between muscle mass and left ventricular end-diastolic (r = 0.66, p < 0.001) or right atrial (r = 0.60, p < 0.01) pressure. Left ventricular relaxation and myocardial stiffness were normal. However, there was an upward shift of the diastolic pressure-volume curve when compared with control values, but this shift was reversed by the administration of nitroprusside.

CONCLUSIONS

Systolic function is normal late after coarctation repair. However, diastolic function can be abnormal with an upward shift of the diastolic pressure-volume curve that is reversed by nitroprusside administration and is probably due to residual left ventricular hypertrophy.

ECG body surface potential mapping many years after successful surgery for coarctation of the aorta

Patients with coarctation of the aorta (CoA) who previously underwent successful surgery are often diagnosed on standard electrocardiograms as having partial right bundle branch block. After surgery 24 patients with CoA had body surface potential mapping (BSPM) with the Case Western Reserve University 180 electrode system; of these 7 had additional aortic stenosis and none had ever had intracardiac communication. The average age at the initial surgery for CoA was 4.0 +/- 3.3 years and at the time of the BSPM it was 12.7 +/- 5.9 years. For the 17 patients with CoA without aortic stenosis the average age at the initial surgery was 5.0 +/- 3.4 years and at the time of the BSPM it was 14.2 +/- 6.0 years. In 11 of the 24 patients, a cardiac catheterization was performed, and each patient demonstrated normal pulmonary artery and right ventricular systolic pressure except for one child with 40 mmHg systolic. In the others all indications were that right ventricular pressure was normal. In 11 of the 24 patients, congestive heart failure had been present in infancy. All 24 cases had evidence for epicardial right ventricular breakthrough on the BSPM, a finding believed to indicate right ventricular activation from endocardium to epicardium via the normal Purkinje system. There were no findings on the BSPM suggesting that right bundle branch block was present. Right ventricular hypertrophy with or without terminal right conduction delay was present on the BSPM in 19 of the 24 patients (9 with additional left ventricular hypertrophy--left ventricular hypertrophy alone in 5). Right ventricular hypertrophy could be considered in 6 of 19 patients in the electrocardiogram, and in 11 of 19 in the vectorcardiogram. The mechanism for the persistent electrocardiographic right ventricular hypertrophy is postulated to involve right ventricular hyperplasia in utero or in early neonatal life, which never disappears.

Ambulatory blood pressure monitoring and left ventricular mass and function after successful surgical repair of coarctation of the aorta

Late cardiovascular morbidity and mortality remain significant despite apparently successful surgical repair of aortic coarctation. Alterations in cardiac function have been reported in normotensive patients who have had successful repair, the reasons for which remain unclear. This study addresses the relation between ambulatory blood pressure measurements and alterations in left ventricular performance in 20 patients with normotension at rest after successful repair of aortic coarctation. Exercise testing, ambulatory blood pressure monitoring and two-dimensional echocardiographic studies in 13 boys and 7 girls (mean age 14.2 +/- 2.31 and 14.7 +/- 3 years, respectively) who had no evidence of recoarctation were compared with the findings in 20 matched control subjects. No difference was found in systolic blood pressure at rest or peak exercise between patients and control subjects. Male patients developed a significant arm/leg gradient at peak exercise. Systolic ambulatory blood pressure was higher throughout the day in the male group. In the female group, systolic blood pressure was higher only during sleep. No difference was found in diastolic blood pressure or heart rate. The transverse aortic arch was smaller and the left ventricular mass greater in all patients. The relation of wall stress to rate-corrected velocity of shortening was 2 SD above normal in 8 of the 20 patients, suggesting that some have enhanced contractility. The E/A ratio on the atrial echocardiogram was significantly reduced in the patient group. Successfully treated patients who are normotensive at rest after operation are still at risk for developing end organ damage, which is probably explained by incipient mild hypertension documented by ambulatory blood pressure monitoring.

Increased stiffness and persistent narrowing of the aorta after successful repair of coarctation of the aorta: relationship to left ventricular mass and blood pressure at rest and with exercise

Fifteen children and adolescents who had repair of coarctation of the aorta before age 15, who were not hypertensive at rest, and who had resting arm-leg blood pressure gradients of less than 20 mm Hg underwent noninvasive evaluation of left ventricular structure and function, aortic stiffness, and residual coarctation as well as bicycle exercise testing. These results were compared with those in 15 age- and sex-matched control subjects. The mean resting age-related systolic blood pressure percentiles (63% versus 46%), transverse aortic stiffness measured by the elastic modulus (Ep) (42.1 versus 23.2 kPa), stiffness index beta (beta) (3.66 versus 2.17), echocardiographic left ventricular fractional shortening (0.42 versus 0.36), left ventricular mass index (99.3 versus 81.0 gm/m2), maximum exercise right arm systolic blood pressure (173 versus 156 mm Hg), and exercise arm-leg blood pressure gradient (35 versus 6 mm Hg) were significantly increased in the coarctectomy patients compared with controls. Univariate correlations in the coarctectomy group showed significant relationships of residual aortic narrowing with left ventricular mass index (r = 0.68, p less than 0.01) and resting systolic blood pressure percentile for age (r = 0.55, p less than 0.05). Residual aortic narrowing did not significantly correlate with aortic stiffness, resting blood pressure gradient, or exercise blood pressure gradient. Neither left ventricular mass index nor resting systolic blood pressure percentile significantly correlated with age of repair or years after repair. These results demonstrate persistent abnormalities in aortic stiffness and left ventricular mass and function after successful repair of coarctation of the aorta in childhood and adolescence.(ABSTRACT TRUNCATED AT 250 WORDS)

Maximal voluntary exercise variables in children with postoperative coarctation of the aorta

Thirty-one children with postoperative coarctation of the aorta underwent maximal graded bicycle ergometry using an electronically braked ergometer and the James protocol; 18 also underwent expiratory gas measurement using a mass spectrometer. Twenty-two age- and gender-matched normal subjects were used as a control group. The mean age at operation was 41 months and the mean age at evaluation was 134 months (mean follow-up interval 93 months). The original surgical repair was subclavian flap repair in 8 patients, end to end anastomosis in 21, patch aortoplasty in 1 patient and tubular graft in 1. Patients exercised until exhaustion and maximal exercise variables were obtained. The maximal voluntary peak heart rate was 183 beats/min (94.6% of predicted value), indicating excellent effort. Mean power was 111% of predicted value and, when measured, maximal oxygen consumption was 89% of predicted value with an anaerobic threshold at 63 +/- 3.5% of exercise time. The observed work variables were not different from values in the control group and were not affected by the type of repair. The mean peak systolic blood pressure was 152 +/- 7.6 mm Hg versus 147 +/- 5.7 mm Hg in the control group (p = NS). Patients who had associated intracardiac lesions had significantly lower maximal oxygen consumption (85 +/- 3% vs. 98 +/- 4% of predicted value). The results suggest that adequate cardiopulmonary function, normal or above average work capacity and normal exercise systolic blood pressure can be obtained in children with satisfactory repair of coarctation of the aorta performed before school age.

Left ventricular function in dogs 1 year after coarctectomy

Juxtaductal aortic coarctation was surgically created in beagle puppies at the age of 2 months and resected at the age of 10 months, after the development of good collateral circulation. Control dogs undergoing sham operations on each occasion were studied in the same environment. Cardiac catheterization was performed 1 year after the coarctectomy to evaluate the recovery of the heart. Cardiac output, heart rate, end-diastolic pressure, and Vmax were similar in both groups of seven dogs, but the systolic pressure gradient (SPG) over the operated area during isoproterenol infusion was significantly higher in the coarctectomized group, with a mean of 8.9 +/- 6.3 (SD) vs. 0.1 +/- 0.3 mmHg (p less than 0.05). The preejection period [PEP, 58 +/- 8 vs. 47 +/- 5 ms (p less than 0.01)], electromechanical delay [EMD, 18 +/- 3 vs. 13 +/- 3 ms (p less than 0.05)], and isometric contraction time [ICT, 39 +/- 7 vs. 32 +/- 4 ms (p less than 0.05)], were all significantly longer in the coarctation group after isoproterenol infusion. The results demonstrate that, even though cardiac output increased adequately during loading and mechanical pumping efficiency was preserved, excitation-contraction coupling was still prolonged. Thus, an anatomical successful coarctectomy, even at the age of 10 months, does not fully restore left ventricular function in dogs after chronic experimental coarctation.

Altered systolic and diastolic function in children after "successful" repair of coarctation of the aorta

We investigated whether left ventricular (LV) structural or functional abnormalities persist in children on long-term follow-up after successful correction of coarctation of the aorta. Two-dimensional directed M-mode and Doppler echocardiographic examinations were performed in 11 such subjects and 22 age-matched control subjects. Digitized tracings were made from M-mode recordings of the LV and Doppler mitral valve inflow recordings to measure septal, posterior wall, and LV dimensions, LV mass, shortening fraction, peak shortening and lengthening velocities, diastolic filling time, peak E velocity, peak A velocity, and velocity time integrals. Despite group similarities in age, body size, and systolic blood pressure, greater fractional shortening (p = 0.0001), indexed peak shortening velocity (p less than 0.001), and greater LV mass index (p less than 0.05) were seen in the coarctation group in the face of lower LV wall stress (p = 0.0001). LV mass index correlated with the resting arm-leg gradient, which ranged from -4 to +10 mm Hg. The coarctation group had decreased early filling (p less than 0.006) with compensatory increased late diastolic filling (p less than 0.05). Diastolic filling abnormalities were prominent in the older coarctation subjects and were related to both systolic blood pressure (p less than 0.001) and LV mass index (p less than 0.01). Despite apparently successful repair of coarctation of the aorta, persistent alterations in both systolic and diastolic LV function and LV mass are present in children at long-term follow-up, which are related to the resting arm-leg gradient.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of proximal left anterior descending and circumflex coronary artery dimensions in aortic valve stenosis and hypertrophic cardiomyopathy

To examine the "adequacy" of basal coronary flow in ventricular hypertrophy, the relation between proximal coronary artery dimensions and regional ventricular mass in aortic valve stenosis (AS) and hypertrophic cardiomyopathy (HC) was evaluated. Coronary artery size was determined by quantitative coronary arteriography while global/regional ventricular mass was calculated using computer-processed biplane 2-dimensional echocardiography. In comparison to 18 "normal" subjects, left anterior descending coronary dimensions were significantly larger in those with hypertrophy (normal 3.32 +/- 0.54, AS 3.82 +/- 0.71, HC 4.72 +/- 0.81 mm, p less than 0.05), with progressive increases in left anterior descending/circumflex coronary diameter ratios (normal 1.04 +/- 0.14, AS 1.18 +/- 0.19, HC 1.25 +/- 0.31, p less than 0.01). Compared to the AS group, indexed anteroseptal mass was greater in the HC subjects (AS 40.9 +/- 8.9 vs HC 72.1 +/- 21 g/m2, p less than 0.001). Both septal width/left anterior descending coronary diameter ratios (AS 3.61 +/- 1.06 vs HC 4.85 +/- 1.17 mm/mm, p less than 0.05) and indexed anteroseptal mass/left anterior descending coronary diameter ratios (AS 11.2 +/- 3.0 vs HC 15.6 +/- 3.4 g/m2/mm, p less than 0.01) were greater in HC subjects. Increased coronary dimensions were observed in both AS and HC, with the greatest changes noted within the left anterior descending distribution in HC, but when analyzed with respect to regional ventricular mass, these subjects demonstrated relative "inadequate" enlargement in coronary artery diameters. Underdeveloped epicardial coronary arteries may contribute to anteroseptal myocardial ischemia, with resultant angina pectoris, increased ventricular ectopic activity and sudden death in HC.

Blood pressure and cardiac output during exercise: a longitudinal study of children undergoing repair of coarctation

Data were examined from 21 children who underwent graded exercise studies prior to and within 5 years after repair of coarctation. A control group of 10 normal children was also studied longitudinally on two occasions. The exercise was performed on an upright bicycle ergometer using a continuous graded exercise protocol. Parameters measured were heart rate, systolic and diastolic blood pressure at rest, and these pressures at the maximal voluntary exercise level. In addition, a subset of patients and controls had measurement of cardiac output by a modified acetylene rebreathing technique. Results indicate that coarctation patients had significant elevation of systolic and diastolic blood pressures at rest (p less than 0.001 for both) and with exercise (p less than 0.02 for both) prior to surgery. The group mean values for systolic and diastolic blood pressure did not differ from control values after surgery; however, some individuals continued to have hypertension at rest when compared to population-based norms. Heart rate, cardiac index, and stroke volume index did not differ from those of control subjects either at rest or during exercise before or after surgery. In conclusion, a group of coarctation patients studied longitudinally demonstrated marked improvement in both systolic and diastolic hypertension after surgery. The findings of normal cardiac output and stroke volume indices may have implications for the etiology of postoperative hypertension.