Three decades of follow-up of aortic and pulmonary vascular lesions in the Williams-Beuren syndrome

The diagnostic criteria of the Williams-Beuren syndrome (WBS) were established almost 3 decades ago. Until now there has been little knowledge about the natural and post-surgical history of vascular lesions in this syndrome. In order to evaluate the long term follow-up of aortic and pulmonary vascular lesions, we have analysed the catheterization data, angiocardiograms, and Doppler-echo measurements in 59 patients who were seen at least twice in our institution between 1961 and 1993. Their follow-up periods ranged from 2.1 to 28.2 years. Of 45 patients with supravalvular aortic stenosis (SVAS) with a mean follow-up period of 12.9 years, it became evident that pressure gradients of less than 20 mm Hg in infancy generally remained unchanged during the first two decades of life. Pressure gradients exceeding 20 mm Hg increased from an average of 35.5 mm Hg to 52.7 mm Hg in 13 patients. Of these, 8 required surgical relief of the narrowing. In 7 patients aortic hypoplasia was documented. In 5 of them the caliber of the aorta showed a tendency towards normalisation within a period of 11.9 to 23.9 years. Of 6 individuals with aortic hypoplasia and surgical relief of SVAS, 4 patients developed restenosis at the distal end of the aortoplasty patch. In contrast, 9 patients with operated SVAS-but without aortic hypoplasia-remained free of restenosis over a period of 11 years (mean). Coarctation occurred in 4/59 patients; restenosis was seen in 2 after 5 and 16 years. Peripheral pulmonary stenosis was followed in 23 patients over 14.4 years (mean).(ABSTRACT TRUNCATED AT 250 WORDS)

Quantification of collateral blood flow in coarctation of the aorta by velocity encoded cine magnetic resonance imaging

BACKGROUND

Knowledge about the volume of collateral flow provides insight into the severity of coarctation of the aorta and may be critical in planning the operative approach. There is currently no method for the quantification of collateral flow in coarctation of the aorta. In this study, we applied velocity encoded cine magnetic resonance imaging (VENC-MR) to establish the flow pattern and volume of collateral flow in the descending thoracic aorta in normal subjects and patients with coarctation, introducing a new possibility to quantify the severity of the coarctation by determining the amount of collateral flow.

METHODS AND RESULTS

VENC-MR was used to measure flow in the proximal and distal descending thoracic aorta in 10 normal subjects. In 23 patients with coarctation, flow was measured near the coarctation site and above the diaphragm. Patients were divided into a group with moderate to severe coarctation and a group with mild coarctation on the basis of clinical gradient between upper and lower extremities and the estimation of the gradient across the coarctation by Doppler echocardiography. The gradient across the coarctation and the degree of anatomic narrowing were also assessed by MR imaging. In normal volunteers, VENC-MR showed a 7 +/- 6% decrease in total flow, from proximal to distal aorta. The interobserver reproducibility was 3.9% to 4.9% (mean, 4.4%). In patients with moderate to severe coarctation, VENC-MR demonstrated an 83 +/- 50% increase in total flow from proximal to distal aorta, yielding a significant change compared with normal subjects (P < .01). Patients with mild coarctation showed a normal flow pattern and no significant change in total flow. There was a significant relation between the amount of flow increase in the distal aorta and the reduction in luminal diameter at the coarctation site (r = .94) as well as the clinical gradient (r = .84).

CONCLUSIONS

This study shows the normal flow pattern in the descending thoracic aorta and its reversal in coarctation due to collateral flow. Thus, VENC-MR can measure collateral flow in coarctation and serves as a unique method for providing this important measurement of the severity of coarctation of the aorta.

Importance of collateral vessels in aortic coarctation: computer simulation at rest and exercise using transmission line elements

Coarctation of the aorta causes arterial hypertension in the upper body and a low blood pressure downstream. Collateral blood vessels compensate by reducing the downstream pressure drop. To study the effect of various coarctation and collateral properties, we designed a computer model of the arterial circulation. The model contains a flow source and a library of subroutines for the lines and connectors. Distributed friction and wall viscoelasticity effects are included. Computer simulation was performed, using published values for vessel dimensions, in an arterial model with a coarctation and one lumped collateral. Rest and two levels of exercise (by increased heart rate) were studied. Without a collateral, we found the downstream pressure of the model was extremely dependent on the size of the coarctation. A collateral vessel reduced the pressure difference between the up- and downstream circulations. For a severe coarctation, the length and the diameter of the collateral were the main factors determining the downstream pressure and flow, whereas wall stiffness of the collateral had little influence. The relationship between mean pressure drop and cardiac output in coarctation was also dependent on the peripheral resistance in different flow beds, especially during exercise.

[Dynamics of the interrelationships of functional and morphologic parameters of the left and right ventricle in coarctation and decoarctation of the ascending aorta]

The contractile and ultrastructural parameters of the left and right ventricles were studied in rabbits 3 weeks after ascending aortic coarctation by a third of the baseline diameter. In other rabbits, the same parameters were studied 1, 2, 3, and 4 weeks after recovery of the normal aortic lumen following three weeks of its narrowing. It was found that a rapid recovery of the parameters under study did not occur after decoarctation despite the fact that left ventricular overload was abolished. A fortnight after decoarctation there was a profound increase in the contractility of the two ventricles and three weeks there was a significant enhancement of cardiomyocytic mitochondrial function.

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.

The influence of coarctation hypertension on the pharmacodynamic behaviour of rat isolated conduit vessels

We have studied the effects of coarctation hypertension on the reactivity of the aorta with respect to alpha 1-adrenoceptor mediated vasoconstriction and methacholine-induced endothelium-dependent vasodilation. The experiments were performed in aortic rings taken from rats that had been subjected to banding of the abdominal aorta, aortic stenosis rats (ASR), and from SHAM operated control rats. As expected, the thoracic aorta was subjected to elevated blood pressure, whereas the pressure in the abdominal aorta region was much lower. Concomitantly, the thoracic and abdominal aorta regions were studied separately as isolated vessels. Both the thoracic and abdominal aortic rings taken from ASR were more sensitive to phenylephrine than those obtained from control rats. The increase in sensitivity cannot be explained by elevated pressure alone and neurohormonal factors are likely to play a role. The maximal relaxation induced by methacholine in thoracic aortic rings obtained from ASR was significantly less when compared with that in preparation taken from SHAM rats. No changes in maximal relaxation were observed in the abdominal aortic rings. It is concluded that i) the enhanced responsiveness of the rat aorta to alpha 1-adrenoceptor stimulation cannot be explained by elevated blood pressure alone and ii) coarctation hypertension impairs the endothelium-dependent relaxation of the aortic region exposed to high blood pressure.

Visualization of flow by vector analysis of multidirectional cine MR velocity mapping

OBJECTIVE

We describe a noninvasive method for visualization of flow and demonstrate its application in a flow phantom and in the great vessels of healthy volunteers and patients with aortic and pulmonary arterial disease. The technique uses multidirectional MR velocity mapping acquired in selected planes. Maps of orthogonal velocity components were then processed into a graphic form immediately recognizable as flow.

MATERIALS AND METHODS

Cine MR velocity maps of orthogonal velocity components in selected planes were acquired in a flow phantom, 10 healthy volunteers, and 13 patients with dilated great vessels. Velocities were presented by multiple computer-generated streaks whose orientation, length, and movement corresponded to velocity vectors in the chosen plane.

RESULTS

The velocity vector maps allowed visualization of complex patterns of primary and secondary flow in the thoracic aorta and pulmonary arteries. The technique revealed coherent, helical forward blood movements in the normal thoracic aorta during midsystole and a reverse flow during early diastole. Abnormal flow patterns with secondary vortices were seen in patients with dilated arteries.

CONCLUSION

The potential of MR velocity vector mapping for in vitro and in vivo visualization of flow patterns is demonstrated. Although this study was limited to two-directional flow in a single anatomical plane, the method provides information that might advance our understanding of the human vascular system in health and disease. Further developments to reduce the acquisition time and the handling and presenting of three-directional velocity data are required to enhance the capability of this method.

[Aortic coarctation and pregnancy. Apropos of 3 cases followed-up during a period of 10 years]

Classically, coarctation of the aorta is poorly tolerated during pregnancy or at least is associated with a risk of rupture of the aorta, rupture of a cerebral aneurysm or, more rarely, cardiac failure or bacterial infection. The authors turned their attention to this association of coarctation of the aorta and pregnancy in the light of 3 cases of pregnancy brought to term in the Department of Cardiology of the Ibn Rochd Teaching Hospital Group, Casablanca, Morocco. During a 10 year period, 20 patients were hospitalised in the department with coarctation of the aorta. There were 10 women, 3 of them pregnant. The mean age of these women was 26, with a range of 24 to 30. All patients had a normal pregnancy, delivery and post-partum, with neither cardiovascular, renal nor cerebral complications. There were no maternal deaths, ruptures of the aorta, cerebrovascular accidents, bacterial infections nor myocardial failure. All the pregnancies were brought to term. One patient was delivered vaginally with the use of forceps after full dilatation facilitating expulsion. One cesarean section with extraction of a live infant was induced at 38 weeks. One patient was lost to follow-up at 7 months and was seen again only after delivery at home, i.e. without supervision but equally without complications. The 3 newborn infants had an Apgar of 10/10 and a birth weight of 3.2-3.5 kilos. There were no spontaneous abortions and no premature deliveries.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Mitral valve hypoplasia in children with isolated coarctation of the aorta

OBJECTIVE

To test the hypothesis that isolated coarctation of the aorta is associated with relative hypoplasia of the mitral valve, even when the valve is morphologically normal.

DESIGN

Cross sectional and Doppler echocardiography were used in a prospective, paired, case control study to compare mitral valve dimensions and diastolic transmitral flow characteristics as indices of left heart development. 40 children with isolated coarctation and 40 size matched controls were examined. Within the coarctation group 14 children with apical diastolic murmurs were compared with 14 size matched patients without murmurs.

SETTING

A supraregional tertiary referral centre for paediatric cardiology.

OUTCOME MEASURES

Mitral valve diameters, measured from the parasternal long axis, short axis, and apical four chamber views; mitral valve cross sectional area measured from the parasternal short axis view; peak early (E) and peak atrial (A) phase diastolic transmitral flow velocities measured by pulsed wave Doppler from the apical four chamber view; derived E/A ratio and pressure half time of decay from peak E.

RESULTS

Mitral valve dimensions were significantly smaller in children with coarctation than in controls for long axis diameter (median 1.74 v 1.90cm, p = 0.0001), short axis diameter (2.21 v 2.28 cm, p = 0.027), and cross sectional area (2.37 v 3.15 cm2, p = 0.001). Peak E and A velocities were significantly higher in patients than in controls (0.9 v 0.82 ms-1, p = 0.013 and 0.61 v 0.51 ms-1, p = 0.007). The only difference between children with coarctation plus murmurs and those without murmurs was a marginally longer pressure half time.

CONCLUSIONS

Smaller mitral valve dimensions and increased diastolic transmitral flow velocities in children with isolated coarctation compared with normal children suggests that coarctation may be part of a generalised hypoplasia of left heart structures.

Arterial reactivity is significantly impaired in normotensive young adults after successful repair of aortic coarctation in childhood

BACKGROUND

Despite successful repair of coarctation of the aorta in childhood, adult survivors often have hypertension at rest or on exercise, and their life expectancy is shorter than normal because of premature coronary and cerebrovascular disease. This may be related to persistent structural and functional arterial abnormalities after surgery.

METHODS AND RESULTS

Using high-resolution ultrasound, we studied the right brachial arteries of 25 normotensive young adults who had undergone successful repair of coarctation in childhood (mean age at repair, 62 months; range, 0 to 167 months, including 8 patients operated on in infancy; mean age at study, 19 years; range, 14 to 27 years) and 50 age- and sex-matched control subjects. We assessed the degree of reactive hyperemia (RH) produced after distal cuff occlusion and release and the changes in arterial diameter in response to RH (with increased flow causing endothelium-dependent dilation) and to glyceryltrinitrate (GTN, an endothelium-independent dilator). The response of the right femoral artery to GTN was also measured in 12 coarctation subjects and 12 control subjects. Studies were performed 13.7 years (range, 7 to 21 years) after surgery. RH was significantly lower in coarctation subjects (343 +/- 130% versus 482 +/- 147%), as were endothelium-dependent dilation (3.8 +/- 3.3% versus 8.8 +/- 3.6%) and GTN response (13.3 +/- 6.0% versus 20.5 +/- 6.1%) (P < .001 for each), reflecting abnormal dilatory capacity in both the resistance and conduit arteries. In contrast, GTN-induced dilation in the femoral arteries was similar to that in control subjects (9.5 +/- 2.6% versus 10.1 +/- 4.1%, P = .70). On multivariate analysis, GTN response and systolic blood pressure at peak exercise were inversely correlated (r = -.52, P = .04). Vascular responses were not related to the age at repair.

CONCLUSIONS

Despite successful repair of coarctation in childhood, arterial dilation is significantly impaired in the precoarctation vascular bed of healthy young adults. This may be an important contributor to exercise-related hypertension and late morbidity or mortality.

More than thirty-five years of coarctation repair. An unexpected high relapse rate

Between 1953 and 1985, 109 consecutive patients (17% with isolated coarctation) younger than 3 years of age underwent resection of aortic coarctation. These patients had nonelective operations because of congestive heart failure or severe systemic hypertension not responding to medical therapy. Special surgical techniques were used to lower the prevalence of restenosis. Hospital mortality was 32% (35 patients). Logistic regression analysis proved that age at operation, pulmonary artery banding, and type of repair were independent predictors of hospital death. Late mortality occurred in 9 patients. Associated cardiac anomalies were an independent prognostic factor for late mortality. The operation rate for recoarctation was low (5.8%). However, the follow-up study revealed that 30 patients (41%) had recoarctation. The Kaplan-Meier estimate of recoarctation is 86% after 30 years' follow-up in patients undergoing classic end-to-end anastomosis with silk sutures (n = 48). None in the group with an "extended" anastomosis and polypropylene sutures (n = 26) had recoarctation. The Cox analysis revealed age at operation under 6 months to be prognostic for recoarctation. Because of the shorter period of follow-up, the extended anastomosis with polypropylene sutures proved not to be a significant prognostic factor for recoarctation. In the late postoperative period (mean follow-up 16.7 years), blood pressure was elevated in 49% of the patients. At last follow-up 27 (36%) of the 74 survivors had aortic valve disease. Patients operated on for coarctation of the aorta under the age of 3 years need lifelong follow-up for detection of restenosis, hypertension, and valvular disease. Reoperation-free rate is not a good criterion to judge the outcome of operation for coarctation. Longer follow-up will be needed to investigate whether or not the use of the extended anastomosis technique with polypropylene sutures lowers the prevalence of recoarctation.

Physiopathogenesis of acute aortic coarctation hypertension in conscious rats

We investigated the role of vasopressin, angiotensin II, and catecholamines in the onset of acute (45-minute) aortic coarctation hypertension in conscious rats. Partial aortic constriction was performed by means of a pneumatic cuff placed around the abdominal aorta above the renal arteries for 15 or 45 minutes. A sham-operated group was used as control. Mean carotid pressure before aortic constriction did not differ between rat groups. Aortic constriction produced a similar increase of mean carotid pressure during 15 minutes (36 +/- 3 to 37 +/- 3 mm Hg above basal levels) and 45 minutes (37 +/- 2 to 39 +/- 3 mm Hg). Plasma vasopressin concentration after 15 minutes of coarctation (4.4 +/- 0.5 pg/mL) did not differ from that observed in control rats (3.0 +/- 0.8 pg/mL), whereas after 45 minutes, it was significantly higher (14.3 +/- 3.3 pg/mL). Plasma renin activity increased significantly after coarctation (21.7 +/- 4.1 and 29.9 +/- 2.9 ng angiotensin I/mL per hour, at 15 and 45 minutes, respectively) when compared with control rats (3.9 +/- 0.5 ng angiotensin I/mL per hour). After coarctation, plasma norepinephrine concentration was consistently reduced, whereas plasma epinephrine concentration did not differ from control rats. In conclusion, these data provide evidence for an effective vasopressor role for vasopressin in the genesis of acute (45-minute) aortic coarctation hypertension in conscious rats. In addition, although the results confirm that the renin-angiotensin system participates earlier in the onset of coarctation hypertension, they rule out a significant vasopressor role for catecholamines in the early development of hypertension.

Coarctation induces alterations in basement membranes in the cardiovascular system

A coarctation hypertensive rat model was used to examine the effects of elevated blood pressure on basement membrane component synthesis by cardiac myocytes and aorta using immunohistochemistry and Northern blot analysis. Carotid arterial pressure increased immediately on coarctation, and left ventricular hypertrophy was maximal within 5 days. In immunohistochemical studies, fibronectin and laminin were increased and the basement membrane chondroitin sulfate proteoglycan decreased in both the subendothelial space and smooth muscle cell basement membranes of the aorta above the clip compared with controls, whereas only fibronectin was elevated in the aorta below the clip. No change in basement membrane staining intensity for the cardiac myocytes was observed. Alterations in steady-state mRNA levels for fibronectin and laminin in the aorta paralleled those observed by immunohistochemical analysis with regard to protein and tissue type affected as well as intensity of the changes. However, changes in mRNA levels (but not protein deposition) for perlecan and type IV collagen were also observed in aortas from hypertensive rats compared with controls. Increases in steady-state mRNA levels for all basement membrane components in the heart and vasculature peaked before maximal cardiac hypertrophy (5 days). These studies indicate that alterations in basement membrane component deposition in the hypertrophied vasculature occur at both transcriptional and translational levels and suggest that the cell attachment glycoproteins fibronectin and laminin may be important factors in the vascular response to elevated transmural pressure.

Magnetic resonance volume flow and jet velocity mapping in aortic coarctation

OBJECTIVES

Nuclear magnetic resonance (MRI) velocity mapping was used to characterize flow waveforms and to measure volume flow in the ascending and descending thoracic aorta in patients with aortic coarctation and in healthy volunteers. We present the method and discuss the relation between these measurements and aortic narrowing assessed by MRI. Finally, we compare coarctation jet velocity measured by MRI velocity mapping with that obtained from continuous wave Doppler echocardiography.

BACKGROUND

The development of a noninvasive imaging method for morphologic visualization of aortic coarctation and for measurement of its impact on blood flow is highly desirable in the preoperative and postoperative management of patients.

METHODS

Magnetic resonance imaging phase-shift velocity mapping was used to measure ascending and descending aortic volume flow in 39 patients with aortic coarctation and in 12 healthy volunteers. Magnetic resonance imaging was also used for anatomic and peak jet velocity measurements. The latter were compared with those available from continuous wave Doppler study in 40% of the patients.

RESULTS

Whereas ascending aortic volume flow measurement did not show significant differences between the patient and healthy control groups, volume flow curves in the descending aorta did show significant differences between the two groups. Peak volume flow (mean +/- SD) was 10.6 +/- 5.3 liters/min in patients and 19.6 +/- 4.7 liters/min in control subjects (p < 0.001). Time-averaged flow was 2.5 +/- 0.9 liters/min in patients and 3.9 +/- 1.1 liters/min in control subjects (p < 0.05). The descending/ascending aorta flow ratio was 0.47 +/- 0.19 in patients and 0.64 +/- 0.08 in control subjects (p < 0.05). These variables correlate well with the degree of aortic narrowing. Peak coarctation jet velocity measured by MRI velocity mapping is comparable to that obtained from continuous wave Doppler study (r = 0.95).

CONCLUSIONS

We established normal ranges for volume flow in the descending aorta and demonstrated abnormalities in patients with aortic coarctation. These abnormalities are likely to be related to resistance to flow imposed by the coarctation and could represent an additional index for monitoring patients before and after intervention.

Coarctation of the aorta in the adolescent and adult: echocardiographic evaluation prior to and following surgical repair

The combination of two-dimensional and continuous-wave (CW) Doppler echocardiographic imaging forms the cornerstone of diagnostic imaging in pre- or postoperative coarctation of the aorta. Because of the frequent association of other congenital heart defects, e.g., bicuspid aortic valve, a segmental imaging approach with multiple image planes should be used. CW Doppler examination from the suprasternal notch should be utilized to assess the degree of obstruction at the coarctation site in all patients. This enhances diagnostic sensitivity. CW Doppler examination can also be applied throughout exercise. Such application allows detection of relative degrees of aortic obstruction following surgical repair of coarctation that may only manifest at elevated levels of cardiac output, e.g., exercise. It aids in the identification of individuals with exercise related systolic hypertension following "successful" coarctectomy and provides a rationale for treatment with beta blockade. The methodology for applying this relatively new technique is discussed.

Balloon angioplasty for aortic recoarctation in children: initial and follow up results and midterm effect on blood pressure

OBJECTIVE

To assess the direct and follow up results of balloon angioplasty for aortic recoarctation with respect to the type of initial operation and to determine the midterm effect on systolic blood pressure.

DESIGN

Prospective study of invasive haemodynamic and angiographic data and non-invasive data on upper body blood pressure.

SETTING

Tertiary referral centre for paediatric cardiology.

SUBJECTS

24 infants and children (age 0.3-16.2 years, mean 5.9 years) who had had surgical correction for coarctation (end to end anastomosis (14 patients) subclavian flap angioplasty (nine), patch angioplasty (one)).

MAIN OUTCOME MEASURES

Peak systolic gradient over the recoarctation and aortic diameters before and directly after angioplasty and at follow up. Upper body blood pressure before and after angioplasty and at latest follow up.

RESULTS

Mean peak systolic gradient initially decreased from 35 (15) to 12 (9) mm Hg (p < 0.001) and was 9 (10) mm Hg at follow up after 1.4 (0.5) years. Patients with a subclavian flap repair showed a slight further decrease in the residual gradient at follow up (p < 0.05). The coarctation diameter increased from 5.3 (2.6) to 7.7 (2.5) mm (p < 0.001), and a further increase to 9.3 (2.9) mm (p < 0.01) was present at follow up after 1.4 (0.5) years without significant changes in other aortic diameters. Upper body systolic blood pressure decreased from 138 (24) to 115 (17) mm Hg after balloon angioplasty, and the effect on blood pressure persisted at a mean follow up of 3.7 years. One patient died of ventricular failure. Femoral artery thrombosis occurred in three patients. In one patient a small aneurysm occurred that had not increased at follow up. In one patient restenosis after angioplasty was redilated successfully. In one patient dilatation of a residual stenosis after angioplasty failed.

CONCLUSION

Balloon angioplasty for recoarctation is effective and is associated with accelerated growth of the dilated segment at follow up in many patients. The complication rate is acceptable. Midterm follow up shows persistent relief of upper body hypertension in most patients.

[Long-term follow-up in patients operated on for aortic coarctation. The echo-Doppler and MRI assessment of left ventricular function and the transisthmic gradient]

BACKGROUND

Hyperdynamic left ventricular function and increased left ventricular mass has been recently reported in the long-term follow-up of patients after successful repair of aortic coarctation (AoCo).

METHODS

We studied 35 patients, mean age 22.7 years (range 1-47), following repair of AoCo in order to evaluate: 1) left ventricular mass and systolic function by M-mode echocardiography in comparison with 20 healthy control subjects; 2) the prevalence of systemic hypertension; 3) systolic blood pressure and the trans-isthmic gradient by CW Doppler at rest and after exercise; 4) subjects with a hypertensive response and/or with a significant trans-isthmic gradient during exercise, correlating such parameters with indexes of left ventricular function and the ratio of aortic isthmus/aortic diaphragmatic diameters (AOI/AOD) by means of Magnetic Resonance (MR). At the time of operation, mean age was 12.4 years (range 1 mo-40 yrs) and the follow-up period was 10.1 years (range 6 mo-26 yrs).

RESULTS

Left ventricular mass index (Mi) was significantly greater in comparison with that of the controls (96.5 +/- 25 vs 71.5 +/- 16.6 g/m2; p < 0.001); the mean velocity of circumferential shortening (mVCFc) was increased (1.4 +/- 0.25 vs 1.2 +/- 0.16 circ/s; p < 0.005); the end systolic meridional stress (ESS) was decreased (37.3 +/- 11.1 vs 47.9 +/- 13.1 g/cm2; p < 0.005) while the peak systolic meridional stress (PSS) was not significantly different in the two groups. Fourteen out of 35 patients (40%) showed an exaggerated mVCFc for the level of ESS, which indicates an increased inotropic state. Hypertension at rest was present in 10 patients (28%). Mean age at the time of operation of the hypertensive group was higher than that of the normotensive one (21.4 +/- 10 vs 8.9 +/- 8.6 yrs; p < 0.001). All patients showed a small systolic gradient across the side of coarctation repair at rest (mean 13.1 mmHg; range 0-30). The exercise test was stopped in 5 patients because of hypertension (> 250 mmHg); 24 patients (80%) showed an exercise-induced hypertension. The mean gradient at maximal exercise was 25.9 mmHg (range 0-52); 6 patients (20%) developed a diastolic gradient. With MR it was possible to evaluate the anatomy of the aortic arch and the descending aorta in all cases. The mean ratio AOI/AOD was 0.81 (range 0.63-1). The age at the time of operation showed a positive correlation with the systolic blood pressure (r = 0.63; p < 0.001) and with Mi (r = 0.45; p < 0.005). The systolic blood pressure and the gradient at maximal exercise also showed a positive correlation (r = 0.40; p < 0.01).

CONCLUSIONS

In the long-term follow-up of patients after successful coarctation repair there are persistent alterations of left ventricular function with hypertrophy, hyperkinesia and increased inotropic state. Hypertension at rest and after exercise could persist despite good surgical results.

Effect of coarctation on matrix content of experimental aortic atherosclerosis: relation to location, plaque size and blood pressure

Cynomolgus monkeys were fed an atherogenic diet for 6 months following surgically produced high-grade (n = 10) or mild (n = 16) mid-thoracic aortic coarctation. A diet-control (DC) group (n = 13) was fed the diet without coarctation. High-grade coarctation (HGC) resulted in 74.1% +/- 8.3% stenosis by aortography prior to sacrifice and was associated with systolic brachial blood pressures of 143.3 +/- 26.0 mmHg and gradients across the stenoses of 36.8 +/- 23.6 mmHg. Mild coarctation (MC) resulted in stenoses of 50.9% +/- 12.9%, brachial systolic pressures of 119.4 +/- 25.7 and gradients of 12.5 +/- 15.2 mm Hg (P < 0.01, P = 0.03 and P < 0.005, respectively, compared with HGC). When total plaque cross-sectional area exceeded 0.8 mm2, the entire arterial circumference was usually involved. HGC resulted in complete sparing or minimal plaque formation in sections distal to the stenoses compared with proximal sections (P < 0.001). There were no significant differences between MC and DC animals in plaque location or size. Matrix content increased with plaque area regardless of degree of stenosis or sampling level (P < 0.01), but lesions with more than 75% matrix content were more numerous in distal than in proximal sections despite their smaller size. The number of plaques with greater than 75% matrix content was increased proximal to HGC (P < 0.04). Thus, distal location and plaque size were independent determinants of plaque matrix content and matrix content was increased proximal to HGC regardless of plaque size. Attempts to evaluate effects of various regimens and interventions on plaque composition need to take location and plaque size, as well as blood pressure differences, into account.

Spectral Doppler flow profiles in neonates with obstructive lesions of the aortic arch

The aim was to assess the value of continuous and pulsed wave Doppler ultrasound in the detection and differentiation of obstructive lesions of the aortic arch in neonates. In 31 neonates with proven arch obstruction (pre- or juxtaductal coarctation in 19 patients; postductal coarctation in five patients; interrupted aortic arch in four patients; aortic arch atresia in three patients), continuous wave Doppler interrogation of the descending aorta from the suprasternal notch revealed a high velocity jet (greater than 2.2 m/s) directed away from the transducer in 12 patients. Of these, four neonates had preductal coarctation, and five postductal coarctation. The remaining three patients had arch interruption or atresia. Image guided pulsed Doppler ultrasound recordings were obtained from the arch upstream from the obstruction, the descending aorta distal to the obstruction, and from the arterial duct. Patients with coarctation had a prominent diastolic flow directed away from the transducer in the arch upstream from the obstruction, representing a diastolic coarctation gradient, or diastolic steal either by the patent arterial duct or by collateral vessels. In contrast, patients with arch interruption or atresia had only a systolic flow signal in the proximal arch. Ductal flow was either bidirectional (preductal coarctation, arch interruption, arch atresia), continuous right to left flow from pulmonary artery to aorta (one case each of juxtaductal coarctation and arch atresia), or continuous left to right flow from aorta to pulmonary artery (postductal coarctation). In neonates wide patency of the duct often precludes the development of a large pressure drop across a coarctation. Conversely, a high velocity signal may be recorded from a patent but restrictive duct. In conjunction with imaging, pulsed Doppler velocity profiles from the arch and patent duct permit a meaningful interpretation of the haemodynamics of arch obstruction.

Fetomaternal blood flow measurements and management of combined coarctation and aneurysm of the thoracic aorta in pregnancy

A pregnant patient presented at 21 weeks of gestation with severe coarctation of the aorta and a large aneurysm (5.4 cm) of the ascending aorta. The patient developed hypertension at gestation week 17. Continuous Doppler wave velocimetry showed a low systolic/diastolic (S/D) ratio in the uterine arteries indicating reduced blood flow to the placenta. The presence of a severe coarctation, aneurysm of the ascending aorta, and hypertension associated with the hemodynamic changes of pregnancy, increases maternal and fetal risk. The literature reviewed disclosed that aneurysm expansion and dissection or rupture on the one hand, and fetal demise on the other, are the greatest risks. The challenge of treating both the patient and the fetus was managed successfully by correction of the coarctation at week 22. Blood pressure normalized a few weeks after the operation, and no expansion in aneurysm diameter was noticed. A normal S/D ratio in the uterine arteries indicated increased blood flow in the uterine arteries. A healthy female was born. Pregnant patients with coarctation of the aorta should have surgical correction preferably in the first or second trimesters.

Effect of bilateral nephrectomy on hypertension produced by acute aortic coarctation

1. The hemodynamic responses to acute (45 min) aortic coarctation were studied in conscious intact (N = 7) or bilaterally nephrectomized (N = 7) Wistar rats (250-320 g). The degree of constriction of the aorta was monitored by reducing aortic flow (measured with a pulsed Doppler flowmeter) to 40% of the basal level. 2. The nephrectomized rats presented a smaller (P < 0.05) increase in carotid pressure (14-17%) than the intact rats (25-36%). Although the aortic constriction reduced significantly the aortic flow to 40% of the basal level in both groups of rats, the calculated change in aortic resistance imposed by coarctation in the intact group was significantly (P < 0.05) higher (167-292%) than that observed (173-183%) in the nephrectomized group, except 5 min after coarctation. 3. The hemodynamic data obtained in the present study confirm our findings that nephrectomized rats display a blunted hypertensive response to acute aortic coarctation which is attributed mainly to the mechanical effect of constriction. In addition, the present data indicate that the release of vasopressor substances triggered by the kidneys in intact subjects are responsible for the gradual increase in aortic resistance during coarctation.