Identified plasma proteins related to vascular structure are associated with coarctation of the aorta in children

BACKGROUND

Coarctation of the aorta (CoA), presenting with local stenosis of the aorta is involved in many cardiovascular processes. However, there has been little research on the mechanism of coarctation of the aorta.

METHODS

Altered proteins were identified by isobaric tag for relative and absolute quantitation (iTRAQ) technology in 8 participants, and further analysed by heatmap, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) and Search Tool for the Retrieval of Interacting Gene (STRING). Of these, two vascular structure-related proteins were further validated by using enzyme-linked immunosorbent assay (ELISA) in a new cohort of CoA patients.

RESULTS

39 differentially expressed plasma proteins were first identified in patients with coarctation of the aorta by iTRAQ. Of these, fibulin-1 (FBLN1) and insulin-like growth factor-binding protein complex acid labile subunit (ALS) were considered candidates and further validation also showed that the level of FBLN1 in the CoA group (8.92 ± 2.36 μg/ml) was significantly higher compared with control group (6.13 ± 1.94 μg/ml), and the level of ALS in CoA children (348.08 ± 216.74 ng/ml) was significantly lower than the level in normal children (619.46 ± 274.08 ng/ml).

CONCLUSIONS

The differentially expressed proteins identified in the plasma from CoA patients indicated that they may play critical roles in CoA and that they could potentially be utilized as biomarkers for diagnosis. Altered vascular related proteins were associated with COA. These results provide a foundation for further understanding and studying the aetiology and pathogenesis of coarctation of the aorta.

Impact of Treatment Modality on Vascular Function in Coarctation of the Aorta: The LOVE - COARCT Study

Background Optimally treated patients with coarctation of the aorta remain at risk for late vascular dysfunction. The effect of treatment modality on vascular function is unknown. The LOVE-COARCT (Long-term Outcomes and Vascular Evaluation After Successful Coarctation of the Aorta Treatment) study was done to compare vascular function in patients with coarctation of the aorta treated with surgery, balloon dilation (BD), or stent implantation. Methods and Results In treated coarctation of the aorta patients without residual coarctation, we prospectively compared aortic stiffness by applanation tonometry and cardiac magnetic resonance; endothelial function by endothelial pulse amplitude testing; blood pressure ( BP ) phenotype by office BP , ambulatory BP monitoring, and BP response to exercise; left ventricular mass by cardiac magnetic resonance; and blood biomarkers of endothelial function, inflammation, vascular wall function, and extracellular matrix. Participants included 75 patients treated with surgery (n=28), BD (n=23), or stent (n=24). Groups had similar age at enrollment, coarctation of the aorta severity, residual gradient, and metabolic profile, but differed by age at treatment. Prevalence of systemic hypertension, aortic stiffness, endothelial function, and left ventricular mass were similar among treatment groups. However, BD patients had more-distensible ascending aortas, lower peak systolic BP during exercise, less impairment in diurnal BP variation, and lower inflammatory biomarkers. Results were unchanged after adjustment for potential confounders, including age at treatment. Conclusions In our cohort of patients without residual coarctation, treatment modality was not associated with major vascular outcomes, even though there were some favorable vascular characteristics in the BD patients. Although this suggests that choice of treatment modality should continue to be driven by likelihood of achieving a good anatomical result, more long-term studies are required to assess the clinical significance of the more-optimal results of secondary markers of vascular function in BD patients. Clinical Trial Registration URL : http://www.clinicaltrials.gov . Unique identifier: NCT 03262753.

Soluble Endothelial Adhesion Molecule Concentration in Patients with Aortic Coarctation

Coarctation of aorta (CoA) is often associated with development of vascular abnormalities and hypertension despite successful correction. The aim of the study was to compare concentrations of adhesion molecules and interleukin-6 (IL-6), an inflammatory cytokine in following groups: children with CoA before operation, chidren with CoA after operation, and healthy control children. Seventeen children with CoA and 18 healthy children (control) were investigated. Blood samples were taken 1 day preoperatively and during followup (10.2+/-7.5 months). Serum concentrations of soluble E- and L-selectin, intercellular adhesion molecule-1 (sICAM-1), and IL-6 were measured by enzyme-linked immunosorbent assay (ELISA). On arms, systolic and diastolic blood pressures decreased after surgery. On legs, only systolic, but not diastolic, blood pressure increased significantly. There was no difference in the concentrations of IL-6, sE-, sL-selectin, or sICAM-1 before and after CoA repair. Postoperative ICAM-1 concentration in children with CoA was significantly higher compared to control (321.7+/-93.4 versus 248.8+/-84.3 ng/mL, P=.002). Only preoperative concentration of L-selectin was higher in children with CoA compared to control (1617.7+/-387.5 ng/mL versus 1271.1+/-266.6 ng/mL). The correction of CoA leads to normalization of leukocyte activity. The markers of endothelial damage and proinflammatory activity are not significantly changed by correction of CoA in young children.

Left ventricular hypertrophy persists after successful treatment for coarctation of the aorta

OBJECTIVES

To evaluate cardiac size and function in patients with coarctation of the aorta (CoA) before and after treatment.

DESIGN

Ventricular size and function were examined by 2- and 3-dimensional echocardiography, and concentrations of natriuretic peptides measured in 15 paediatric patients before repair, and one, 6, and 12 months thereafter. Controls comprised 15 children.

RESULTS

Before repair, mitral inflow velocities and left ventricular (LV) size and wall thickness were higher in patients. Thicknesses of interventricular septum and LV posterior wall decreased after repair but increased to initial level one year thereafter. The LV end-diastolic diameter remained larger than in controls despite successful repair. The size of right ventricle increased and levels of natriuretic peptides decreased during follow-up. Levels of natriuretic peptides correlated with the smallest diameter of CoA segment and diastolic indices of LV function.

CONCLUSION

LV hypertrophy persists and LV size remains larger than in controls after successful repair even in normotensive patients with normal growth of CoA segment. This may be due to remodelling of ventricles and the aorta caused by CoA.

Reduced left ventricular dimension and normalized atrial natriuretic hormone level after repair of aortic coarctation in an adult

Although unusual in the older patient, coarctation of the aorta can be an occult cause of cardiomyopathy. This report describes a 53-year-old man with new-onset heart failure symptoms, global left ventricular (LV) dysfunction, and underlying aortic coarctation. Surgical correction resulted in reduced LV size, resolution of symptoms, and normalization of atrial natriuretic hormone levels.

Evaluation of immunomodulatory biomarkers in a pressure overload model of heart failure

STUDY OBJECTIVES

To characterize the immunomodulatory response in a pressure overload model of heart failure, and to further validate this animal model of human heart failure.

DESIGN

Randomized, controlled, animal study.

SETTING

Large university research facility.

ANIMALS

Twenty-seven, male, Sprague-Dawley rats.

INTERVENTION

The rats underwent either aortic constriction or a sham procedure.

MEASUREMENTS AND MAIN RESULTS

Six months after the surgical procedure, echocardiographic measurements were obtained, the animals were sacrificed, and plasma samples were taken to measure concentrations of biomarkers. As six (40%) of the 15 rats in the aortic-constriction group died before the 6 months, only nine rats from this group underwent immunomodulatory evaluation. Compared with the sham procedure, aortic constriction increased the left ventricle:body weight ratio in the rats (p=0.0016) It also decreased the velocity of circumferential shortening (p=0.08) and increased myocardial expression of atrial natriuretic factor, beta-myosin heavy chain, and fibronectin (p<0.05). Concentrations of the proinflammatory mediator interleukin (IL)-1beta and the counterregulatory mediator IL-10 also significantly increased (p<0.04) in the group that underwent aortic constriction compared with the group that underwent the sham procedure. Nonsignificant increases (mean change approximately 50-180%) were also observed for IL-2, IL-6, and leptin concentrations.

CONCLUSIONS

In this classic animal model of heart failure, a systemic immunomodulatory response was evaluated after 6 months of pressure overload resulting in myocardial decompensation and, in some cases, mortality. The findings are similar to the immunomodulatory response that may be observed in human heart failure. These novel results further define this model of heart failure and suggest another aspect of its relevance to human heart failure with regard to pressure overload and the immunomodulatory response.

Exercise testing in adults after repair of aortic coarctation: evaluation of cardiopulmonary exercise capacity and B-type natriuretic protein levels

The aim of the study was to investigate, in adult patients after successful repair of aortic coarctation, potential relationships between B-type natriuretic peptide levels and exercise capacity and the following factors: arterial hypertension, residual stenosis of the ascending aorta, and age at the time of surgery. The study group comprised 74 patients (45 men) aged 19 to 61 years (mean, 31.2 +/- 9.8 yr), who had undergone surgery at the age of 0.5 to 34 years (mean, 10.4 +/- 6.8 yr). The surgery was performed between 5 and 34 years earlier (mean, 21.4 +/- 6.2 yr). A subgroup with residual aortic stenosis (significant when > or =25 mmHg) comprised 32 patients; a subgroup without residual stenosis comprised 42 patients. Patients were also divided into subgroups without arterial hypertension (n=32), with exercise-induced arterial hypertension (n=10), and with persistent arterial hypertension (n=32). All patients were in New York Heart Association functional class I. The control group comprised 30 healthy subjects (18 men) aged 26 to 46 years (mean, 32.2 +/- 6.6 yr). After testing exercise capacity in accordance with a modified Bruce protocol, we concluded that the exercise capacity of adults is reduced after surgical repair of aortic coarctation. This reduction is more pronounced in patients who have arterial hypertension, but it is unaffected by residual stenosis of the descending aorta. Serum B-natriuretic peptide concentrations, as determined by immunoradiometric assay, are significantly elevated, which may result from pressure overload of the left ventricle or from residual myocardial lesions due to coarctation repair at an older age.

An evaluation of acid-base changes following aortic cross-clamping using transcutaneous carbon dioxide monitoring

To investigate the cause of acidosis following release of an aortic cross-clamp, we measured tissue PCO2 using a transcutaneous (TC) CO2 monitor placed below the level of the cross-clamp in 10 patients undergoing aortic arch surgery. Following placement of the aortic cross-clamp, the TC CO2 value from the lower extremity increased from 41 +/- 4 to 92 +/- 41, whereas there was no change in the TC CO2 value from the upper extremity. With release of the cross-clamp, end-tidal CO2 increased by 6.2 +/- 1.9 mmHg, the upper TC CO2 increased by 8.4 +/- 4.8 mmHg, and the lower extremity TC CO2 value returned to baseline. During cross-clamping, there was an increase in the base deficit of 4.3 +/- 2.9 when comparing the baseline arterial blood gas value with the one obtained after cross-clamp release (p = 0.0004). These data demonstrate that the acidosis occurring during aortic cross-clamping is a mixed metabolic and hypercarbic acidosis. Appropriate treatment includes the provision of adequate minute ventilation to ensure CO2 removal and the use of sodium bicarbonate based on the degree of metabolic acidosis demonstrated by arterial blood gas analysis.

[B-natriuretic peptide and cardiological emergencies in childhood]

The increase in B-natiuretic peptide (BNP) is well correlated with cardiovascular symptoms in adults. Its use in children is recent and only partially evaluated. The authors undertook a prospective study of BNP concentrations and its kinetics in 54 children with an average age of 15 months (5 days to 11 years) admitted as paediatric emergencies. The symptoms were dyspnoea (60%), shock (15%), suspicion of Kawasaki disease (15%) and other (10%). Twenty children had BNP levels of more than 100 pg/ml related to decompensation of known congenital heart disease in 7 patients (average BNP 462 +/- 323 pg/ml), due to neonatal coarctation in 2 patients (BNP > 3000 pg/ml), due to cardiomyopathy in 6 patients (BNP= 2576 +/- 1215 pg/ml), due to an arrhythmia in 1 patient (BNP= 3754 pg/ml) and to Kawasaki disease in 4 patients (BNP= 521 +/- 448 pg/ml). Thirty-four children had BNP values of less than 100 pg/ml; 29 had no cardiac disease and 5 had known congenital heart disease with other symptoms. Measuring BNP is quick and economical and is a valuable aid in the diagnosis of cardiac dysfunction in symptomatic children in the emergency room. High BNP values seem to be correlated with the severity of the cardiac disease. Low BNP values seem to have a good negative predictive value in children without underlying cardiac disease. The interpretation of intermediary values, especially when there is previous cardiac disease, is more difficult in view of the absence of known threshold values for different haemodynamic situations. Further studies are required to determine the value of this test for the follow-up and setting up of prognostic values in children with congenital heart disease.

Clinical signs of heart failure are associated with increased levels of natriuretic peptide types B and A in children with congenital heart defects or cardiomyopathy

AIM

To study whether natriuretic peptide types B (BNP) and A (ANP) reflect clinical signs of heart failure (CSHF) in children with congenital heart defects or cardiomyopathy resulting in different types of haemodynamic situations, such as pressure overload in coarctation of the aorta (CoA), volume overload in ventricular septal defect (VSD) or systolic dysfunction in dilated cardiomyopathy (DCM).

METHODS

Blood samples for plasma P-BNP and P-ANP were taken before procedures during regular investigation from 26 children (9 CoA, 11 VSD and 6 DCM). The ordinary paediatric cardiologist performed the cardiac evaluation and the data were retrieved from medical charts. CSHF was considered positive if two of the following criteria were fulfilled: reduced physical capacity, feeding disorders, dyspnoea, tachypnoea, hepatomegaly and oedema. The statistical methods were non-parametric.

RESULTS

0/9 children with CoA, 5/11 with VSD and 6/6 with DCM had CSHF. In children with CSHF, P-BNP and P-ANP were higher, 263 ng l(-1) (range 47.5-1300) and 303 ng l(-1) (range 168-466), than in those without CSHF, 12.3 ng l(-1) (range 4.8-30.8) and 42.9 ng l(-1) (range 13.7-189), respectively (p < 0.001, Mann-Whitney U-test), irrespective of the diagnosis. The same relationship was also found in the group of children with VSD.

CONCLUSION

Plasma levels of ANP and BNP increase in children with CSHF. This increase is seen irrespective of whether it is due to systolic dysfunction, as in children with DCM, or to a volume overload with a normal systolic function, as in children with VSD.

Vascular and neuroendocrine components in altered blood pressure regulation after surgical repair of coarctation of the aorta

STUDY OBJECTIVE

To investigate potential vascular and neuroendocrine determinants of altered blood pressure (BP) regulation in patients previously operated on for aortic coarctation.

DESIGN, SETTING AND PATIENTS

We prospectively re-evaluated 45 patients operated on for aortic coarctation at Strasbourg University Hospital over a 13-year period. Four of these patients were less than 2 years old at the time of the operation and four were older than 20 years. Patient age and time since the operation were on average 21+/-13 years and 8+/-3 years, respectively. Surgery consisted of a resection with end-to-end anastomosis for 18 patients, angioplasty (8), prosthesis (4) or sub-clavian flap (15).

RESULTS

Despite repair of the coarctation, about 40% of the patients showed an abnormal BP status at rest. The majority of these patients had uncomplicated borderline hypertension. The orthostasis test as well as the BP circadian rhythm were frequently abnormal. While the ankle/arm systolic pressure index measured at rest was generally within the normal range, diminished carotid-femoral pulse wave velocity was observed. Plasma adrenaline and aldosterone levels were elevated in about 50% of the patients examined.

CONCLUSIONS

These new findings suggest that there are 'cause and effect' relationships between aortic structural and functional vascular abnormalities, and augmented plasma adrenaline and aldosterone in some patients after coarctation repair. These phenomena are likely to be involved in altered BP regulation and might result in recurrent hypertension.

Elevated arginine vasopressin and lowered atrial natriuretic factor associated with hypertension in coarctation of the aorta

Impairment of humoral and neural regulation of blood pressure may contribute to preoperative and postoperative hypertension in coarctation of the aorta and may also affect the release of vasopressin and atrial natriuretic factor. Because vasopressin and atrial natriuretic factor have potent vasoactive effects, we measured plasma vasopressin and atrial natriuretic factor levels by radioimmunoassay before operation and for 5 days after operation in 11 patients aged 9 months to 12 years undergoing coarctation repair and in 12 control patients undergoing other cardiovascular operations. Six patients in the coarctation group required minimal antihypertensive therapy (group I) and five required prolonged intravenous antihypertensive therapy (group II). Before operation, vasopressin levels correlated with systolic blood pressure for all patients in the coarctation group (r = 0.83, p < 0.01) whereas atrial natriuretic factor levels did not. Before operation, atrial natriuretic factor levels were lower (28 +/- 5 vs 41 +/- 7 and 50 +/- 8 pg/ml, p < 0.05) and vasopressin levels were higher (28 +/- 6 vs 5.4 +/- 0.9 and 7 +/- 3 pg/ml, p < 0.05) in group II than in group I or control patients. Vasopressin levels were higher (p < 0.05) on the day of operation and on postoperative days 2 through 5 in group II than in group I and in control patients. Atrial natriuretic factor levels were lower during the day of operation in group II than in group I or in control patients (26 +/- 7 vs 51 +/- 16 and 50 +/- 7 pg/ml, p < 0.05) and remained lower than control values on postoperative days 1 and 3 through 5. Elevated vasopressin and lowered atrial natriuretic factor levels may contribute to preoperative and postoperative hypertension in coarctation.

Acute renal failure with ACE inhibition in aortic coarctation

A 43 year old man with inoperable aortic coarctation and severe hypertension requiring near maximal anti-hypertensive treatment was admitted in severe heart failure. After 2 weeks of treatment the heart failure and blood pressure were incompletely controlled and angiotensin converting enzyme (ACE) inhibitor was started. Serum creatinine was normal before starting the ACE inhibitor and on discharge from hospital. The patient was re-admitted a week later with gross fluid retention and in renal failure. In the absence of alternative causes, a diagnosis of ACE inhibitor-induced renal failure was made and treatment was stopped. The patient required haemodialysis for 2 days and within 1 week the renal function had reverted to normal and has remained so for 1 year. We propose that the renal haemodynamics in severe aortic coarctation are similar to those in bilateral severe renal artery stenosis and advise caution in the use of ACE inhibitors for adults with aortic coarctation.

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.

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.

[Evaluation of peripheral circulation in infants with aortic coarctation by transcutaneous pO2 measurement]

Fourteen patients 6 weeks to 8 months of age with coarctation of the aorta (CA) were examined before and after correction of the anomaly. In inspiration of increasing concentrations of O2 the TavO2 was progressively delayed below CA as compared to the region above CA, which reflected latent tissue oxygen deficiency. After CA correction the TavO2 values were practically the same in both regions. Measurement of TavO2 at two points during inspiration of increased O2 concentrations (0.65) may be an objective method for confirming the existence of CA in infants.

Operative factors, not hemodynamics, modify hormones in repair of coarctation

This study was designed to evaluate separately the influence of restoration of distal pulse pressure and the influence of factors related to operation upon hemodynamic and hormonal alterations accompanying repair of canine aortic coarctation. Eight normal adult dogs underwent a sham operation and served as controls. In 10 dogs the thoracic aorta was transfected and reanastomosed. In 10 dogs aortic coarctation was created within 1 week of birth by banding the aorta just proximal to the ductus ligament, thereby fixing lumenal diameter at 1 to 2 mm. Studies were performed in the latter animals 18 months after operation. These dogs were subdivided into two groups: one (n = 6) underwent surgical repair of the coarctation; in the other (n = 4), the coarctation was repaired and an occluder was placed on the aorta to maintain distal aortic pulse pressure at its diminished preoperative level. Normal distal pulse pressure was restored in these animals by releasing the occluder 1 week after recovery from the repair of coarctation. Each dog was studied in the conscious state before the definitive procedure and again 24 hr later. Plasma renin activity increased significantly after operation in the sham and in the transection groups. Renin activity and proximal blood pressure were significantly elevated and distal pulse pressure was diminished preoperatively in both the repair and the occluder groups. After their respective definitive procedures, the elevation in renin activity and in proximal pressure persisted in the repair group but decreased in the occluder group.(ABSTRACT TRUNCATED AT 250 WORDS)

Progressive vascular lesions in Williams-Beuren syndrome

We report two patients with Williams-Beuren syndrome. The first patient showed no evidence of coarctation of the aorta at the first examination. Seven years later, she developed coarctation of the aorta. In the second patient, we found the progression of renal artery stenosis by serial angiography. We report that vascular lesions may be progressive in Williams-Beuren syndrome.

[Activity of lipolytic enzymes in rabbit plasma during myocardial injury]

Dynamics of lipolytic enzymes activity was studied in pre- and postheparin blood plasma of rabbits with hemodynamic heart overloading, with acute local ischemia of myocardium and with diphtheria intoxication. Development of all these pathological processes, impairing myocardium, was accompanied by appearance of lipolytic activity specific for intralipid and for activated intralipid in preheparin blood plasma, by an increase in activity of lipolytic enzymes in postheparin blood plasma as well as by alteration in the spectrum of blood lipoproteins. These alterations depended on the character of disease, impairing the heart muscle.

Effects of exercise on plasma renin, aldosterone and catecholamines before and after surgery for aortic coarctation

The pre- and postoperative values of blood pressure, pulse rate, plasma renin activity, plasma aldosterone concentration and circulating catecholamines were studied in a group of 12 patients with uncomplicated aortic coarctation before and after exercise. Mean age of patients studied was 21.5 years. Postoperative studies were carried out on average 204 days after surgery. Following operation, both resting and exercising upper extremity pressures decreased. Six out of the 11 patients still had an abnormally high exercising blood pressure when compared with a normal control group of six persons. Postoperative pulse rates during exercise were significantly higher than pre-operatively (P less than 0.01). No statistically significant differences between pre- and postoperative values, and between patients and normal controls were found in the hormonal studies. This study suggests that the renin-aldosterone-system does not have a major role in the maintenance of the hypertension associated with coarctation of the aorta.

Preoperative and postoperative renin levels in coarctation of the aorta

We studied plasma renin activity (PRA) in eight children before and after surgical correction of aortic coarctation. These eight children underwent a combination of low-sodium diet and diuresis before surgery, and PRA was measured shortly thereafter. Thirty-two to 51 months after successful surgical correction, PRA was measured again. The mean PRA was 21.4 +/- 1.3 ng/ml/hour (+/- SD) preoperatively and 5.5 +/- 1.5 ng/ml/hour postoperatively. These findings provide further evidence of the significance of increased renin-angiotensin activity in patients with aortic coarctation.

A model of delayed aortic coarctation employing arterial and venous catheters for chronic blood sampling in conscious dogs

We have developed a reproducible model of cardiac hypertrophy in conscious, unrestrained dogs after recovery from surgical trauma. The model has many potential applications due to the availability of non-stressful blood sampling from four arterial and/or venous vascular locations. Samples of blood for biochemical or pharmacological measurements were obtained from the carotid and femoral arteries as well as the pulmonary artery and inferior vena cava. Left ventricular hypertrophy up to 128% of the non-operated control animals was produced at 96 h post-intraluminal aortic coarctation. Inflation of a balloon in the descending aorta increased outflow resistance and resulted in hypertrophy. Hemodynamic parameters of cardiac function were obtained via a Swan-Ganz cardiac output catheter located permanently in the pulmonary artery. Complications observed in the dog model were minimal and mortality did not occur during the experimental period. This animal model employing multiple implanted catheters for blood sampling plus the ability to impose aortic coarctation in the unrestrained animal provides a flexible model system for biochemical and pharmacological research.

[Effect of ethanolamine on corticosterone concentration in experimental myocardial hyperfunction in the white rat]

An initial step of experimental myocardium hyperfunction, caused by coarctation of the subphrenic part of abdominal aorta, was accompanied by a distinct increase in content of corticosterone in rat blood and adrenal glands. Administration of ethanolamine at a dose of 10 mg/kg decreased the hormone content under conditions of heart hyperfunction. The data obtained suggest that adrenal gland cortex was activated in response to the myocardium pathology as well as that content of corticosterone in blood and adrenal glands might be regulated by administration of ethanolamine.

Hypertensive mechanisms in coarctation of the aorta. Further studies of the renin-angiotensin system

The mechanisms of hypertension in coarctation remain to be clearly defined. In other hypertensive states, abnormal plasma renin activity (PRA) has been unmasked by the depletion of extracellular volume and the use of angiotensin antagonists. In a group of patients with coarctation, preoperative and postoperative evaluations of the renin-angiotensin system have been performed. Before operation, a group of patients with coarctation and a group of normal control subjects both underwent salt restriction followed by diuresis. A standard angiotensin antagonist (saralasin) test was performed on the patients with coarctation, and they demonstrated excessive renin-angiotensin activity compared to the control subjects. Following operation, paradoxical hypertension developed in all of the patients. Repeat saralasin test in these patients again revealed excessive angiotensin activity in the same patients as preoperatively. It appears that the renin-angiotensin system plays a more active role in coarctation than previously believed.

Plasma renin activity in coarctation of the aorta before and after surgical correction

In 37 patients with coarctation of the aorta, arterial blood pressure and ambulant plasma renin activity (PRA) were determined before and, in 15 patients, after surgical correction. The systolic blood pressure was raised in all the cases and the diastolic pressure was raised in 30 patients. Ambulant PRA was increased in 11 patients when compared with normal subjects of similar age. Twelve of the 15 operated patients had a significant decrease of systolic pressure after operation. Eight had raised PRA, and in 7 of these PRA fell to normal after operation and the blood pressure also fell; in 1 patient the decrease of PRA was unaccompanied by a fall in blood pressure. Though there was no significant correlation between the changes in blood pressure and PRA after operation it seems possible from our results that the renin-angiotensin system may be activated and contribute to the raised arterial pressure which occurs in patients with aortic coarctation.

[Importance of determining the renin activity in the blood plasma of the renal veins in symptomatic hypertension]

In patients with vasorenal hypertension blood plasma renin activity was always higher on the side of the lesion than on the contralateral side, whereas in patients with nephrogenic hypertension and coarctation of the aorta this value was within physiological norm. After reconstructive operations in vasorenal hypertension (in an unilateral lesion) a hypotensive effect was produced when the ratio of blood plasma renin activity on the side of the lesion to that on the healthy side was 1.4 and more. The ratio of renin activity in plasma of blood in the renal veins is an important diagnostic and prognostic criterion.

Pathogenesis of paradoxical hypertension after coarctation resection

The pathogenesis of paradoxical hypertension after resection of coarctation of the aorta was investigated by comparing the course of seven children undergoing repair of coarctation with five acyanotic children undergoing elective cardiovascular surgery. During the first 24 hours after surgery, all coarctation patients demonstrated a rise in systolic blood pressure (35 +/- 15.5 mm Hg; P less than 0.001), a significant depression in cold pressor test response, and only a slight elevation in plasma renin activity. In the next 24-72 hours, coarctation patients developed a rise in diastolic blood pressure (26.8 +/- 10.6 mm Hg; P less than 0.001), plasma renin activity (22.9 +/- 10.2/ml/hr; P less than 0.001) and fluid retention. By contrast, control patients had no significant postoperative changes. Abdominal pain occurred in five coarctation patients during the period of maximal plasma renin activity. The data suggest that the sympathetic nervous system may be responsible for the initial phase of hypertension after coarctation resection and that the renin angiotension system plays a major role in the second phase of hypertension and in the pathogenesis of mesenteric arteritis.

Acute post-traumatic coarctation of the abdominal aorta

An unusual case of coarctation of the abdominal aorta following trauma in reported. The resultant supratenal aortic constriction was associated with severe hypertension and elevated plasma renin concentration. Gradual aortic dilation at the suture site was accompanied by remission of hypertension and return of plasma renin concentration to normal. Correlation of laboratory and hemodynamic changes resulting from this unusual case of abdominal coarctation is discussed.

Plasms renin acitivity in coarctation of aorta before and after surgery

Plasma renin acitivity was measured in II cases of coarctation of the aorta before and after operation. The values of plasma renin activity in the recumbent position before operation were significantly lower than in the control group. After surgery plasma renin activity rose to normal levels. There was no correlation between plasma renin activity levels and arterial blood pressure. The renin-angiotensin system seems not to be involved directly in the maintenance of hypertension in patients with aortic coarctation.

[Computation of mixed venous oxygen saturation in intracardial shunts and its dependence on age, anesthesia and premedication]

In patients with an intracardiac shunt, the oxygen saturation of the mixed venous blood cannot be measured, but it must be estimated from the oxygen saturation in the superior and in the inferior vena cava. We have evaluated the results of patients who had definitively no shunt and who had been catheterized for other reasons. Based on statistical principles we developed formulas to calculate the oxygen saturation of the mixed venous blood. We examined three group of patients: a) Children up to 11 years catheterized during general anaesthesia (58 patients) b) Children up to 11 years catheterized after premedication but without general anaesthesia (53 patients) c) Adults catheterized without general anaesthsia (59 patients) We found that the formulas from the patients who had been catheterized during general anaesthesia were quite different from those without anaesthesia. In the patients without an anaesthesia the superior vena cava was coupled with a much higher factor than the inferior vena cava; in patients with anaesthesia, the contribution of the inferior vena cava was stronger. The age of the patients had no significant influence on our formulas.

Plasma renin activity in patients with coarctation of the aorta. A comment of the pathogenesis prestenotic hypertension

In 10 patients with coarctation of the aorta, plasma renin activity was measured after recumbency and orthostatism in peripheral venous blood and, in some cases, in renal venous blood also. In nine of these patients, basic plasma renin values and those obtained under stimulatory conditions lay within normal range, and only in one patient were the values elevated. However, since this patient displayed the lowest gradient of mean arterial blood pressure proximal and distal to the stenosis, it can be regarded as improbable that the elevation in plasma renin activity was caused by the coarctation. Plasma renin activity in the renal venous blood of both kidneys, which was measured in three patients, showed no elevation.

On the basis of observations of other authors and of our own studies it can be concluded that the kidneys can contribute to the development of prestenotic hypertension in acute constriction of the aorta in experiments with animals, but in chronic coarctation in animals or in man the humoral or renal theory has no importance to the pathogenesis of hypertension.