Non-invasive evaluation of left ventricular systolic function late after coarctation repair: influence of early vs late surgery

The study was designed to assess non-invasively the long-term effect of coarctation repair on systemic blood pressure, left ventricular (LV) muscle mass (LMM) and LV systolic function. Blood pressure and pressure gradients across the coarctation site were measured at rest and during exercise. LV systolic function and LMM were assessed by echocardiography. Twenty-eight patients late after successful coarctation repair were divided according to their age at surgery into two groups: group 1: < 1 year (10 days-12 months, mean 0.2 years) and group 2: > 1 year (1-19 years, mean 9.7 years). A group of age- and sex-matched patients with normal LV function served as controls. LMM was increased late postoperatively in both groups irrespective of the age at surgery and was correlated significantly with the elevated systolic blood pressure and the residual pressure gradient at exercise. End-systolic wall stress was normal at rest and the stress/velocity relationship revealed normal contractility in all patients. Despite successful operation of aortic coarctation, residual LV hypertrophy persists 2 to 19 years after surgery irrespective of the age at surgery. LV systolic function is normal. Hypertrophy can be explained by the residual arm-leg pressure gradient during exercise which persists even after successful repair.

Contractile responses to Bay K 8644 in rats with coarctation-induced hypertension

This study examines potential-operated calcium channel function in rats made hypertensive by aortic coarctation. The hypothesis that channel function is influenced by elevated arterial pressure was tested by comparing contractile responses to elevated K+ and to the potential-operated calcium channel agonist, Bay K 8644, in aortic segments above (thoracic) and below (abdominal) the coarctation that are exposed to hypertensive and normotensive pressures, respectively. To control for vessel differences, the effects of Bay K 8644 were also examined in abdominal aortae from two-kidney, one-clip hypertensive rats. Sensitivity to K+ (EC15) was significantly greater in both thoracic and abdominal aortae from coarctation-hypertensive rats than in those from normotensive sham rats. In the thoracic aorta, maximal contractile response to Bay K 8644 (normalized to contraction produced by 100 mM K+) was significantly greater in coarctation-hypertensive rats (124 +/- 9%) than in sham rats (12 +/- 6%). However, Bay K 8644 did not elicit contraction in abdominal aortae from either group. When [K+]o was increased (19.2 mM), thoracic aortae from coarctation-hypertensive rats were more sensitive to Bay K 8644, but there were no differences in maximal responses among thoracic and abdominal aortae. Bay K 8644 evoked dose-dependent contraction in all abdominal aortic strips from two-kidney, one-clip hypertensive rats (maximum = 68 +/- 11%). In summary, vascular responsiveness to Bay K 8644 is increased in the thoracic but not abdominal aorta from coarctation-hypertensive rats, whereas sensitivity to elevated K+ is increased in both vessels. Enhanced K+ sensitivity in the abdominal aorta may be related to general effects of the cation on membrane potential. However, augmented responsiveness to Bay K 8644 suggests a specific alteration in the function of potential-operated calcium channels that is dependent upon elevated blood pressure and is not due to differences in responsiveness between the thoracic and abdominal aortae.

The neurologic complications of congenital heart disease

In recent years, an aggressive approach to the medical and surgical management of patients with complex cardiac malformations has led to an increased survival rate in this group of patients. Some of these patients often have significant residual cardiac defects and, at times, an unstable hemodynamic status. The cumulative risk for neurologic complications in this group of patients is expected to be substantial. Because the overall population of patients with congenital heart disease encompasses an increasing proportion of these high-risk patients, careful surveillance for potential neurologic complications is indicated.

Noninvasive long-term follow-up after coarctation repair

Thirty patients operated on for aortic coarctation while less than 3 years of age underwent magnetic resonance imaging, digital subtraction angiography, and bicycle exercise testing 14 to 33 years (mean, 22 years) after operation. Diameters of the aorta at the site of the anastomosis, of the distal arch, and of the aorta at the level of the diaphragm were measured in the images. Blood pressures were obtained from the right arm and leg before and after exercise. Patients were divided into three groups according to blood pressure data: group I, resting gradient less than 30 mm Hg and exercise gradient less than 50 mm Hg; group II, resting gradient less than 30 mm Hg and exercise gradient greater than 50 mm Hg; and group III, resting gradient 30 mm Hg or greater. A control group underwent the same test. The frequency of hypertensive patients was greater in groups II (58%) and III (100%) than in group I (20%). The anastomosis/descending aorta ratio seen in digital subtraction angiograms was smaller in group II and III patients. Exercise blood pressure gradient correlated significantly (r = -0.48; p = 0.009) with anastomosis/descending aorta ratio in digital subtraction angiograms but not in magnetic resonance images. Twenty of 30 patients (67%) had a significant anatomic narrowing at the site of the anastomosis. Blood pressure data correlated with diameters measured in digital subtraction angiograms but not with diameters measured in magnetic resonance images.

Aortic "recoarctation" at rest versus at exercise in children as evaluated by stress Doppler echocardiography after a "good" operative result

The mechanism for exercise systolic hypertension after a "good" operative repair of coarctation of the aorta remains speculative. Twenty-four children (mean age +/- SD 10.3 +/- 3.8 years) were studied with continuous-wave Doppler echocardiography while they performed continuous, graded, maximal treadmill exercise. Patients were free of "recoarctation" based on conventional resting echocardiography. Measurements of ascending and descending aortic peak instantaneous systolic velocity were obtained at rest, throughout exercise and during recovery. Results were compared with 24 age- and gender-matched control subjects. Fifteen patients were normotensive (group 1) (peak systolic blood pressure, 147 +/- 21 mm Hg) and 9 developed systolic hypertension during exercise (group 2) (196 +/- 32 mm Hg) (p < 0.05) (control subjects, 143 +/- 21 mm Hg). Descending aortic peak systolic velocity at rest ranged from 1.50 +/- 0.27 m/s in the control group to 2.57 +/- 0.57 m/s (group 1) and 2.93 +/- 0.43 m/s (group 2) (p < 0.05, group 2 vs control). Differences were amplified at peak exercise with systolic velocity increasing to 4.26 +/- 0.61 m/s in group 2 but only to 3.61 +/- 0.70 m/s in group 1 and 2.26 +/- 0.38 m/s in control subjects (p < 0.05, group 2 vs group 1 and control). Seven patients developed a descending aortic diastolic velocity during exercise. Stepwise linear regression analysis identified 2 variables to be significant determinants of peak exercise systolic blood pressure in the "total" patient group: (1) age at exercise testing, and (2) descending aortic peak systolic velocity at peak exercise (r2 = 0.88, p < 0.001) (group 2, alone - r2 = 0.98, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

[The usefulness of continuous Doppler in the diagnosis of aortic coarctation]

Were studied 32 patients with coarctation of the aorta by continuous wave Doppler ultrasound in order to assess the usefulness of this diagnostic method. Nineteen (59%) had native coarctation and 13 (41%) recoarctation. Seventeen (53%) were male and 15 (47%) female. The mean age when diagnosis was performed was 56 +/- 54 months. We found associated anomalies in 15 patients (46%). We studied 5 variables of the continuous Doppler curve at the descending aorta that were compared with those of a control group of 20 patients without cardiac anomalies. The variables were: peak systolic gradient (50.1 +/- 18 mmHg; VS 7.6 +/- 3 mmHg; p = 0.001); peak diastolic gradient 18.5 +/- 10 mmHg; VS 0.49 +/- 0.5 mmHg; p = 0.001; systolic velocity half time 151.5 +/- 40 msec; VS 102 +/- 17 msec; p = 0.01; diastolic velocity half time 132.2 +/- 82 msec; VS 7 +/- 14 msec; p = 0.001 corrected acceleration time (169 +/- 26 mmHg; VS 138 +/- 22 mmHg; p = 0.01). Systolic gradient was highly sensitive (100%) and specific (100%). Diastolic gradient and time to half peak diastolic velocity were very specific (100%) and less sensitive (93% and 62%). There were 6 false positive and 4 false negative when we used the time to half peak systolic velocity (sensitivity 81%, specificity 72%). We conclude that continuous Doppler is a useful method in the diagnosis of coarctation of the aorta. The most important variables of Doppler curve are systolic gradient, diastolic gradient and time to half peak diastolic velocity. All patients with coarctation of aorta had at least 2 variables altered.

Decreased perfusion pressure modulates renin and ANG II type 1 receptor gene expression in the rat kidney

To determine whether decreased perfusion pressure affects the abundance and distribution of renin and its mRNA and the expression of the angiotensin II type 1 (AT1) receptor gene within the kidney, adult male Sprague-Dawley rats were subjected to aortic coarctation proximal to the renal arteries (Coarc, n = 8) and compared with sham-operated rats (Sham, n = 6). Renal renin distribution was determined by immunocytochemistry using a specific polyclonal antibody against rat renin. Renin mRNA was assessed by in situ hybridization to a 35S-labeled oligonucleotide complementary to rat renin mRNA. Kidney AT1 mRNA levels were determined by Northern analysis using a 1,133-base pair rat AT1 cDNA. Femoral arterial blood pressure, measured 24 h after surgery, was lower in Coarc than in Sham rats (75 +/- 5.4 vs. 122 +/- 2.3 mmHg, P < 0.05). Aortic coarctation increased the percent of juxtaglomerular apparatuses (%JGA) containing renin and its mRNA (85 +/- 2.5 and 66 +/- 2.8 vs. 49 +/- 5.3 and 36 +/- 1.7%, Coarc vs. Sham, P < 0.05) and the intensity of hybridization signals (497 +/- 89 vs. 71 +/- 12 grains/JGA, Coarc vs. Sham, P < 0.05). In addition, recruitment of renin gene expressing cells was observed along afferent arterioles in Coarc rats, whereas renin and its mRNA were limited to the JGAs in Sham rats. Renal AT1 receptor gene expression was threefold lower in Coarc than in Sham rats. We conclude that reduction of perfusion pressure after abdominal aortic coarctation acutely enhances renin gene expression and downregulates AT1 receptor gene expression.(ABSTRACT TRUNCATED AT 250 WORDS)

Oscillometric blood pressures in the arm, thigh, and calf in healthy children and those with aortic coarctation

Comparing blood pressure (BP) obtained in the arm with that obtained in the thigh or calf is important in the diagnosis of aortic coarctation. However, normative mean and range of differences in BP between the arm and lower extremity sites are not available for normal children. It is also not known how accurately the differences in BP between the arm and the lower extremity sites predict the pulsed Doppler estimation of systolic pressure (SP) gradient across an aortic coarctation. To resolve these questions, the authors obtained two BP measurements by an oscillometric (Dinamap) method in the arm, thigh, and calf in 74 healthy children aged 4 to 16 years. Oscillometric BP was also obtained in 21 children aged 3 to 17 years with preoperative or postoperative aortic coarctation and BP gradients were compared with that estimated by the pulsed Doppler method. Overall, SP was higher in the thigh and calf than in the arm. The gradients in SP expressed as arm SP minus calf SP [S(A-C)] and arm SP minus thigh SP [S(A-T)] were significantly greater in children 4 through 8 years old than in those 9 to 16 years old. The S(A-C) was -9.3 (+/- 7.4 SD) mm Hg in the 4- through 8-year group and -5.0 (+/- 6.9 SD) mm Hg in the 9- to 16-year group. The S(A-T) was -7.1 (+/- 6.8 SD) mm Hg in the 4- through 8-year group and -2.4 (+/- 7.7 SD) mm Hg in the 9- to 16-year group.(ABSTRACT TRUNCATED AT 250 WORDS)

Follow-up using magnetic resonance imaging in adult patients after surgery for aortic coarctation

Functional impairment, aneurysma formation, and restenosis are well known complications after surgery for coarctation of the aorta. In order to assess long-term results, 25 adults were studied by physical examination, exercise tests, and magnetic resonance imaging after an interval ranging from 1 to 28 years since surgery for coarctation. Fifteen patients had arterial hypertension at rest, five additional patients showed hypertension on exertion only. Magnetic resonance imaging showed pathological changes of the aorta in all patients. An aneurysm of the ascending aorta was seen in four patients, a circumscript aneurysm in the descending aorta at the site of surgery was found in three patients. Restenosis of the descending aorta occurred in three patients. In eight patients the left subclavian artery was distally displaced and dilated in eleven patients. In order to initiate appropriate treatment of specific complications such as restenosis, aneurysm, and arterial hypertension, regular checks are necessary in patients with surgery for aortic coarctation. In addition to clinical examination and exercise tests, magnetic resonance imaging is an effective noninvasive imaging method for follow-up.

[The sports fitness of patients operated on for aortic coarctation: assessment by exercise Doppler echocardiography]

BACKGROUND

The aim of this study was to assess the utility of Doppler echocardiography both at rest and during isotonic exercise in evaluating competition eligibility of patients with repaired coarctation of the aorta (CoAo).

METHODS

Seventeen young patients (11 male, 6 female; mean age 17.1 +/- 7.9 years) with previous surgical repair of CoAo were examined. Mean follow-up after repair was 10.3 +/- 3.5 years. All patients underwent complete Echocardiographic examination (M-mode, 2D and Doppler) and an exercise test on an ergometric bicycle, with continuous wave Doppler monitoring of flow velocity in descending aorta, with a transducer positioned in the suprasternal notch. Peak and mean Doppler gradients in descending aorta were measured both at rest and during exercise, using the simplified Bernoulli equation. According to peak Doppler gradient at rest, patients were divided into two subgroups: Group IA = patients with peak gradient lower than 25 mmHg; Group IB = patients with peak gradient greater than 25 mmHg. Finally, 17 healthy subjects (Control Group), matched for age and body surface area, were examined.

RESULTS

Systolic and diastolic blood pressure both at rest and during exercise were not significantly different in the 3 groups. Patients of Group IB showed a significant increase of left ventricular mass (124.0 +/- 24.4 vs 85.8 +/- 24.1 g/m2, p < 0.01), and during exercise, a significant increase of peak gradient (68.3 +/- 27.2 vs 23.5 +/- 9.0 mmHg, p < 0.0001) and mean gradient (34.8 +/- 11.5 vs 11.9 +/- 5.0 mmHg, p < 0.0001) at the level of the descending aorta. In patients of Group IA, echocardiographic parameters were not different in comparison with the Control Group, whereas Doppler gradients during exercise were only slightly greater than those observed in the Control Group (peak gradient 36.9 +/- 13.0 vs 23.5 +/- 9.0 mmHg, p < 0.05; mean gradient 19.6 +/- 6.0 vs 11.9 +/- 5.0 mmHg, p < 0.05). However, 4 patients of Group IA showed a peak gradient during exercise greater than 40 mmHg (this value was equivalent to the mean value plus 2 Standard Deviations, observed in the Control Group) with the presence of diastolic flow, whereas exercise systolic blood pressure was lower than 200 mmHg.

CONCLUSIONS

Thus, as a result of this study aimed at evaluating competition eligibility in patients with repaired CoAo, two subgroups of patients have to be distinguished according to Doppler echocardiography results: a) patients with peak Doppler gradient at rest greater than 25 mmHg, for whom competition is forbidden; b) Patients with peak gradient lower than 25 mmHg who must be investigated with exercise Doppler echocardiography to exclude an abnormal increase of Doppler gradients, even if exercise blood pressure is within normal limits.

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.

[Echo-Doppler, exercise test, NMR in the follow-up of surgically treated aortic coarctation]

Persistent hypertension is one of the causes of sudden death which sometimes happens in patients operated on for coarctation of the aorta. Seven patients operated on for coarctation of the aorta were examined using exercise testing (Treadmill-Bruce), Echo-Doppler and NMR. Pressure gradients between the right upper and lower limbs were compared with those of normal young people and evaluated using NMR. The authors conclude that the patients operated on have resting blood pressure and pressure gradients, both resting and during exercise, greater than normal. Some patients operated on, with normal resting blood pressure and a slight gradient, can develop hypertension during exercise and a significant pressure gradient. Significant gradients during exercise are correlated to isthmic obstruction which is visible on the NMR. Follow-up after surgical repair of coarctation of the aorta cannot exclude measurement of exercise pressure gradients. This gives more physiological information compared with pressure gradients measured at rest.

Balloon angioplasty of adult aortic coarctation

OBJECTIVE

To examine the use of balloon angioplasty in the treatment of native adult aortic coarctation.

DESIGN

Haemodynamic and angiographic studies to establish the diagnosis of aortic coarctation were established before carrying out the procedure in all patients.

SETTING

All the studies and angiographic procedures were performed in a large district general hospital within the departments of cardiology and radiology. There was careful perioperative monitoring. The mean hospital stay was three days.

PATIENTS

15 adult patients (with clinical, haemodynamic, and angiographic evidence of native aortic coarctation) were considered for this treatment. 13 were offered balloon angioplasty. One was excluded, as there was no significant gradient across the lesion. One patient had complete atresia at the site of the coarctation.

INTERVENTIONS

Percutaneous transluminal balloon angioplasty was carried out with balloon catheters diameter 2 mm less than the diameter of the aorta immediately below the left subclavian artery to minimise the possibility of tearing the aortic wall.

MAIN OUTCOME MEASURES

Abolition or significant reduction of the preoperative gradient was achieved in all 13 patients treated. Reduction in blood pressure of the upper limb was also achieved in all of the patients. Only four patients required continued antihypertensive treatment. Two patients developed false aneurysms after the procedure and required surgery. No deaths occurred. These results compare favourably with conventional surgery and are much more economical.

CONCLUSIONS

Balloon angioplasty could become the first line treatment for all patients with native adult aortic coarctation, but longer term follow up is required to validate this.

Effects of duration of pressure overload on the reversibility of impaired coronary autoregulation in rats

The aim of this study was to determine the effects of duration of pressure overload on the reversibility of impaired coronary autoregulation in hypertropied hearts. The experiments were performed on 38 anesthetized male Wistar rats aged 6 to 8 weeks. The ascending aorta was banded for 4 or 10 weeks, then in some rats the bands were removed for 4 weeks. We estimated coronary hemodynamics in a model consisting of isolated non-working hearts perfused with Tyrode's solution containing bovine red blood cells and serum albumin. Myocardial mass increased significantly in 4 and 10-week banded groups compared to controls. Four weeks after debanding in 4- and 10-week banded groups, the value returned to that of controls. Autoregulation gain was significantly lower in banded groups than in controls in the range between 50 and 100 mmHg of coronary perfusion pressure. Although the gain normalized in the debanded group after 4 weeks of banding, the value in the debanded groups after 10 weeks of banding remained less than zero between 25 and 150 mmHg of perfusion pressure. In transient flow response to a stepwise increase of perfusion pressure within the autoregulatory range, promptly increased flow was followed by more rapid and greater decrease in controls than in banded groups. The flow response regressed in the debanded group after 4 weeks of banding, while it remained unchanged in the debanded group after 10 weeks of banding. Thus, duration of pressure overload alters the regression of impaired coronary autoregulation in cardiac hypertrophy.

Doppler evaluation of normalized peak filling rate in normal children and children with left ventricular outflow obstruction

To evaluate the early diastolic peak filling rate of the left ventricle, three groups of children (normal children, patients with aortic valvular stenosis, and patients with aortic coarctation) were examined with the peak filling rate normalized to stroke volume calculated from the mitral valve inflow Doppler recording as the peak E velocity divided by the velocity time integral. The normal value for this index in children was 6.78 +/- 0.99 SV/sec and did not vary with age, weight, body surface area, or heart rate. Compared with normal subjects, both patients with aortic stenosis and patients with coarctation had increased left ventricular mass, but patients with aortic stenosis had decreased normalized peak filling rates (5.3 +/- 0.84 SV/sec, p < 0.01), while patients with coarctation had normal rates (6.79 +/- 0.98 SV/sec, p = 0.97). Compared with patients with aortic coarctation, patients with aortic stenosis had higher Doppler gradients. Thus the Doppler index of peak filling rate normalized to stroke volume is particularly useful in children because it is independent of heart rate, age, weight, and body surface area. Patients with coarctation may have normal peak filling rates normalized to stroke volume despite increased left ventricular mass because of milder obstruction or better coronary artery perfusion compared with that of patients with aortic stenosis.

Coarctation of the aorta in infants: does the aortic arch grow after repair?

Infants with coarctation of the aorta frequently require a corrective operation during the first year of life. These patients frequently have a smaller than normal transverse aortic arch. Despite good repairs with different techniques, the proximal transverse aortic arch often remains smaller than normal. The hemodynamic molding theory predicts that growth of the aortic arch should occur when normal flow is established through the aortic arch. Preoperative and postoperative aortograms were reviewed in patients who underwent subclavian flap aortoplasty for the repair of coarctation. Patients were divided into two groups. Subclavian flap aortoplasty was performed at 1 month of age or earlier in group I, and at more than 1 month but less than 1 year of age in group II. Aortograms performed in patients without coarctation were used as age-matched controls (group III). The transverse aortic arch in groups I and II did grow and were compared with the control group. Group I patients achieved more growth than those in group II. No aortic arch gradients were present at postoperative follow-up.

Aortic wall stress profile after repair of coarctation of the aorta. It is related to subsequent true aneurysm formation?

True aneurysm formation at the site of coarctation repair has been increasingly recognized after synthetic patch aortoplasty. A mathematical model was developed to determine the aortic wall stress profile after coarctation repair with this technique.

METHODS

A two-dimensional nonlinear mathematical model and a three-dimensional finite element model were developed for different physiologic, geometric, and materials properties variables, which were incorporated into an idealized coarctation repair.

RESULTS

The models demonstrated that the major variable affecting stress levels in the aortic wall after coarctation repair was the patch geometry. If the patch was allowed to balloon out, the aortic wall stress increased out of proportion to the increase in aortic diameter because of nonlinear effects. The maximal aortic wall stress concentration occurred opposite the patch. Patch stiffness was also an important variable, with a lower stiffness (subclavian flap repair) leading to a higher aortic wall stress for the same patch geometry as a synthetic patch repair. Inferences: Development of true aneurysms after coarctation repair by synthetic patch aortoplasty is likely to result from excessive aortic wall stress due to patch geometry.

Balloon angioplasty for native coarctation of the aorta in children and adults: factors determining the outcome

Balloon angioplasty was performed in 46 patients (age 2-40 yr) with discrete native coarctation of aorta. Patients with associated patent ductus arteriosus, aberrant subclavian artery and aneurysms were excluded. The peak systolic gradient across the coarcted segment decreased from 52.1 +/- 18.5 mmHg to 18.6 +/- 14.8 mmHg (p less than 0.001), and the diameter of the coarcted segment increased from 3.6 +/- 1.7 mm/m2 to 9.1 +/- 3.2 mm/m2 (p less than 0.001). Follow-up haemodynamic and angiographic studies performed in 21 patients at 13.1 +/- 6.9 months after angioplasty, showed good results in 15 patients. Four patients undergoing haemodynamic study and 4 other patients undergoing noninvasive evaluation were graded as having bad results at follow-up. In 5 of these patients the poor results were due to primary failure of angioplasty in relieving the gradient, and three developed re-coarctation after initial fall in the trans-coarctation gradient. Four risk factors were identified on univariate analysis, which were associated with significantly larger residual gradients at follow-up: (1) size of isthmus/size of coarcted segment ratio less than 3.0; (2) size of post-coarctation descending aorta/size of isthmus ratio greater than 1.75; (3) size of coarcted segment after angioplasty/size of coarcted segment before angioplasty ratio less than 2.0; and (4) size of balloon/size of coarcted segment ratio less than 3.0. The presence of one or more risk factors was associated with bad late results. On multivariate analysis the ratio of balloon size/coarcted segment size was found to be the sole independent predictor of the late outcome (p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Continuous wave Doppler echocardiography after surgical repair of coarctation of the aorta

OBJECTIVE

To find how closely pressure gradients across the aortic arch derived from Doppler echocardiography reflect gradients measured by catheter after surgical repair of coarctation of the aorta.

DESIGN

Pressure drop across the aortic arch was measured simultaneously by continuous wave Doppler and double lumen catheter in 20 patients with repaired coarctation of the aorta.

RESULTS

The peak pressure drop estimated by Doppler was almost invariably higher than the peak to peak gradient measured by catheter, as might be expected. Wide variation was seen between the Doppler measured pressure drop and instantaneous peak gradient measured by catheter, ranging from +22 to -17 mm Hg. The reasons for these differences are unclear but are probably related to a combination of complex flow dynamics in the aortic arch, difficulty in closely aligning the Doppler beam with flow, and inability to measure flow velocity immediately proximal to the site of the surgical repair with continuous wave Doppler.

CONCLUSIONS

Continuous wave Doppler echocardiography may significantly overestimate or underestimate the pressure drop after repair of coarctation and it should be interpreted with caution in individual patients. Catheterisation with angiography remains the reference standard for assessment of surgical repair of the aortic arch.

Balloon angioplasty for native aortic coarctation

From May 1987 to August 1990, eighteen patients underwent balloon angioplasty for native aortic coarctation. The age of the patients ranged from four to fifty six years (mean age 17.5 years). The procedure was successful in all cases with a reduction in the peak gradient across the coarctation from 61 +/- 19 mm Hg to 11.7 +/- 8.1 mmHg (p < 0.05). The coarcted segment increased from 4.5 +/- 1.9 mm to 10.7 +/- 3.9 mm (p < 0.05). Peak gradient at six to twelve months follow up, obtained in ten patients, was 19.8 +/- 10.1 mmHg (p = NS). There were no life threatening complications, although seven patients had local vascular problems after the procedure. In two patients, there was persistence of hypertension necessitating drug therapy. On haemodynamic and angiographic restudy in 10 patients, one patient had restenosis and none had aneurysm formation. We conclude that balloon angioplasty is a safe, and less invasive alternative to surgery for native aortic coarctation with gratifying immediate and short term results.

Augmented norepinephrine and renin output in response to maximal exercise in hypertensive coarctectomy patients

To evaluate a possible neural or renal contribution to the hypertension that occurs in some patients following coarctation of aorta repair, 35 patients underwent graded bicycle exercise with serial measurements of plasma norepinephrine concentrations and plasma renin activity. Sixteen patients with coarctectomy who had systolic or diastolic hypertension at peak exercise were compared with 19 normotensive patients with coarctectomy. The average time interval between coarctation repair and study was significantly longer (p less than 0.05) in the hypertensive group than in the normotensive patients (12.8 +/- 4.8 versus 8.7 +/- 2.2 years). The heart rate response to exercise was similar for both patient groups. The systolic blood pressure in the hypertensive group was higher than in the normotensive group at rest in the supine and upright positions and at 5 minutes of recovery, in addition to peak exercise, and the diastolic blood pressure was increased at peak exercise. Plasma norepinephrine concentrations were significantly higher at peak exercise and during recovery in the hypertensive group than in the normotensive patients. Plasma renin activity was also significantly higher in the hypertensive group at peak exercise. These data suggest that patients with coarctectomy who have a hypertensive response to exercise have an augmented sympathetic nervous system output and increased plasma renin activity that may lead to peripheral vasoconstriction at peak exercise and that may contribute to the development of their hypertension.

[Late results of the subclavian flap repair for aortic coarctation-effects on the left upper limb]

Late results of the subclavian flap repair for the aortic coarctation and effects on the left upper limb were evaluated on 9 patients who were operated on and had been continuously followed up at Hyogo Kenritsu Amagasaki Hospital. Their mean age at operation was 2.3 years (range 9 days-5.7 years), and mean follow-up period 5.9 years (range 3.1 years-8.3 years). Reoperation for restenosis was necessary in one patient and it proved the initial aortotomy and patch angioplasty had not been extended sufficiently beyond the stenotic segment. In the remaining 8 patients, the mean values of arm-to-leg systolic pressure gradient and peak flow velocity at the descending aorta by Doppler echocardiogram were 2.5 mmHg and 1.9 m/sec respectively. Length and arm circumference of the left upper limb were all significantly shorter than those of the right side. The left systolic brachial pressure and core temperature of the hand were also significantly low comparing with those of the right side. No patients, however, complained the ischemic symptoms of the left upper limb. In conclusion, the subclavian flap repair is thought to be a safe and long effective procedure for the aortic coarctation.

[The endovascular correction of aortic coarctation]

The endovascular balloon dilatation of the aorta coarctation performed on indications and at the optimal terms is the radical correction of the defect with a pronounced positive effect in 90% of 43 patients. No aneurysms and restenoses were found. Retained collaterals allow avoidance of the abdominal syndrome and paradoxical hypertension. Contraindications for catheter angioplasty are thought to include agenesia or considerable hypoplasia of the aorta, the absence of the aorta lumen in the zone of coarctation, its considerable length and the presence of prestenotic aneurysms. A short and noncomplicated postoperative period makes the method sufficiently economical.