Continuous wave Doppler echocardiography and coarctation of the aorta: gradients and flow patterns in the assessment of severity

Umbilical artery half peak systolic velocity deceleration time: a novel Doppler parameter for prediction of neonatal outcomes in pregnant women with preeclampsia

PURPOSE

To assess the effectiveness of half peak systolic velocity deceleration time (hPSV-DT) in predicting neonatal outcomes in pregnant women with preeclampsia and to compare its usefulness with the conventional umbilical artery (UA) pulsatility index (PI) approach.

METHODS

A prospective cohort study was conducted among pregnant women with preeclampsia who were admitted to the Department of Perinatology, Ministry of Health Ankara City Hospital between 01 September 2022 and 01 January 2023 at 28-41 weeks gestational age. 55 patients were divided into two groups: the study group with UA hPSV-DT value < 5th percentile (n = 22) and the control group with UA hPSV-DT value ≥ 5th percentile (n = 33). UA hPSV-DT calculates the time in milliseconds needed to halve the maximal velocity of the UA waveform using Doppler ultrasonography.

RESULTS

Birth weight, gestational age at birth, 1st minute APGAR, 5th minute APGAR, and umbilical cord pH values were significantly lower in the anormal hPSV-DT group (p < 0.05). Additionally, the rates of admission to NICU, respiratory distress syndrome (RDS), delivery time < 34 weeks, and birth weight < 2500 g were significantly more frequent in the anormal hPSV-DT group compared to the normal hPSV-DT group (p < 0.05). UA-PI > 95th percentile was detected in only 2 (8%) of 23 patients whose newborns were admitted to the NICU (p = 0.149), while hPSV-DT < 5th percentile was detected in 16 (69%) of 23 patients (p < 0.001). According to ROC analysis, the area under the curve was 0.82 (95% CI 0.06-0.28) for admission to the NICU. The best balance of sensitivity/specificity in ROC curves was 221.5 (82.6% sensitivity, 69.1% specificity, p < 0.001).

CONCLUSION

UA hPSV-DT was successful in predicting composite adverse perinatal outcomes in pregnant women with preeclampsia. It is a promising novel method that is accurate, quantitative, reproducible, and easily applicable. With further studies, this method may be a primary diagnostic tool in the management of high-risk pregnancies and in determining the optimal timing of delivery.

Clinical, Experimental, and Computational Validation of a New Doppler-Based Index for Coarctation Severity Assessment

BACKGROUND

Long-term morbidity including hypertension often persists in coarctation patients despite current guidelines. Coarctation severity can be invasively assessed via peak-to-peak catheter pressure gradient (PPCG), which is estimated noninvasively via simplified Bernoulli equation and conventionally reported as peak instantaneous Doppler gradient (PIDG). However, underlying simplifications of the equation limit diagnostic accuracy. We studied the diagnostic performance of a new Doppler-based diastolic index called the continuous flow pressure gradient (CFPG) versus conventional indices in assessing coarctation severity.

METHODS

In a rabbit model mimicking human aortic coarctation, temporal blood pressure waveforms revealed the diastolic instantaneous pressure gradients and spectral Doppler features impacted by coarctation severity. We therefore hypothesized that CFPG provides superior correlation with coarctation gradients measured invasively. PIDG and CFPG were quantified using color flow echocardiography in humans and rabbits with discrete coarctations. Results were compared with PPCG in rabbits (n = 34) and arm-leg systolic gradients (n = 25) in humans via 1-way analysis of variance, Pearson's correlation, linear regression, and Bland-Altman analysis.

RESULTS

A threshold of CFPG ≥ 4.6 mm Hg was identified via the Youden index as representative of PPCG ≥ 20 mm Hg (the current guideline value for coarctation intervention) in rabbits, while a CFPG ≥1.0 mm Hg represented an arm-leg systolic gradient ≥20 mm Hg in humans. Accuracy measures revealed superior correlation of CFPG (R2 > 0.80) and mild receiver operating characteristic improvement (area under the receiver operating characteristic curve, 0.94-0.95) compared with PIDG (R2 < 0.63; area under the receiver operating characteristic curve, 0.89-0.95). Inter-/intraobserver variability tested by intraclass correlation coefficient revealed measurement reliability with differences ≤8.2% and 10.7%, respectively. Computational simulations of anesthetized versus conscious hemodynamics showed parameters were minimally impacted by isoflurane inherent in the data used to derive CFPG. These results confirm the potential diagnostic accuracy of CFPG in echocardiography-based coarctation severity assessment. We are optimistic that CFPG will be useful for translation of results from preclinical studies that revisit current guidelines to limit morbidity in humans with aortic coarctation.

Long-term cardiovascular outcome of Williams syndrome

OBJECTIVE

Cardiovascular lesions are the leading cause of morbidity and mortality in patients with Williams syndrome. Recent studies have rebutted conventional reports about the natural course of cardiovascular anomalies in Williams syndrome.

DESIGN

Retrospective study.

SETTING

Single tertiary center.

PATIENTS

Eighty patients with Williams syndrome followed up for more than 5 years.

INTERVENTIONS

Not applicable.

OUTCOME MEASURES

Long-term outcome of cardiovascular lesions, peak velocity change in obstructive cardiovascular lesions over time, post-interventional courses of disease-specific intervention, and intervention-free survival of obstructive cardiovascular lesions.

RESULTS

The median follow-up duration was 11.0 (5.1-28.3) years. Among 80 patients, supravalvular aortic stenosis (87.5%) was the most common cardiovascular lesion, followed by branch pulmonary stenosis (53.8%), mitral valve prolapse (22.5%), and aortic arch hypoplasia/coarctation (5.0%). During the follow-up period, the peak flow velocity of supravalvular aortic stenosis did not change on peak Doppler echocardiography. Initially, severe supravalvular aortic stenosis was aggravated (P < .027). Conversely, the peak velocity of branch pulmonary stenosis decreased (from 3.08 to 1.65 m/s; P < .001) within age 3.2 (0.4-6.9) years. Even the group with severe branch PS improved over time. Twenty-two patients (27.5%) with Williams syndrome underwent disease-specific interventions without mortality, mostly for supravalvular aortic stenosis or mitral valve prolapse. No patient in the late-onset and initially mild supravalvular aortic stenosis group needed intervention and 37.5%, 48.4%, and 65.1% in initially moderate and severe supravalvular aortic stenosis groups needed intervention at age 5, 10, and 20 years, respectively. Unlike the conventional therapeutic concept, the intervention for branch pulmonary stenosis was almost unnecessary.

CONCLUSIONS

In Williams syndrome, initially severe supravalvular aortic stenosis worsened over time and most branch pulmonary stenoses, including those in the severe group, improved spontaneously. Most patients with branch pulmonary stenosis did not require disease-specific intervention. Surgical repairs for cardiovascular abnormalities in Williams syndrome showed favorable results.

Diastolic velocity half time is associated with aortic coarctation gradient at catheterization independent of echocardiographic and clinical blood pressure gradients

OBJECTIVE

The most accurate noninvasive parameter to predict whether a patient with aortic coarctation will meet interventional criteria at catheterization remains elusive. We aim to determine the best independent echocardiographic predictors of a coarctation peak-to-peak pressure gradient ≥20 mm Hg at catheterization, the accepted threshold for intervention.

DESIGN

Retrospective query of our catheterization database from 1/2007 to 7/2016 for the diagnostic code of aortic coarctation was performed. Multiple echocardiographic measurements and blood pressure gradients prior to cardiac catheterization were collected. Univariate correlation of variables with the continuous catheterization peak were calculated using Spearman's rho. Univariate association with peak-to-peak gradient at catheterization ≥20 mm Hg was tested using Mann-Whitney U test and the Pearson chi-square test or Fisher's exact test. Multivariable logistic regression assessed the independent association of the clinically relevant metrics with gradient at catheterization ≥20 mm Hg.

RESULTS

Sixty-eight patients met study criteria (median age 9.25 years), of whom 84% underwent intervention at catheterization. Echocardiographic peak and mean coarctation velocity, indexed systolic and diastolic velocity half times (SVHTi, DVHTi), and blood pressure gradient all had moderate correlation (Spearman's rho = 0.529-0.617, P < .001) with the continuous catheterization gradient and were significantly associated with the binary outcome of catheterization peak ≥20 mm Hg (P < .001). Logistic regression found echocardiographic mean systolic gradient (OR 1.213 [95% CI 1.041-1.414]) and DVHTi (OR 1.039 [95% CI 1.004-1.074]) independently associate with catheterization peak ≥20 mm Hg after controlling for blood pressure gradient (OR 1.066 [0.987-1.150]).

CONCLUSIONS

Most echocardiographic estimates show moderate correlation with arch gradient at catheterization. Noninvasive four extremity blood pressure gradient is significantly associated with peak-to-peak gradient ≥20 mm Hg. DVHTi may provide a unique independently associated echocardiographic estimate of coarctation severity. Further study of these variables with larger cohorts may allow for development of predictive models to direct catheterization.

Doppler Flow Pattern and Arterial Stiffness in Patients with Aortic Coarctation

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

The aortic reservoir-wave as a paradigm for arterial haemodynamics: insights from three-dimensional fluid-structure interaction simulations in a model of aortic coarctation

BACKGROUND

The reservoir-wave paradigm considers aortic pressure as the superposition of a 'reservoir pressure', directly related to changes in reservoir volume, and an 'excess' component ascribed to wave dynamics. The change in reservoir pressure is assumed to be proportional to the difference between aortic inflow and outflow (i.e. aortic volume changes), an assumption that is virtually impossible to validate in vivo. The aim of this study is therefore to apply the reservoir-wave paradigm to aortic pressure and flow waves obtained from three-dimensional fluid-structure interaction simulations in a model of a normal aorta, aortic coarctation (narrowed descending aorta) and stented coarctation (stiff segment in descending aorta).

METHOD AND RESULTS

We found no unequivocal relation between the intraaortic volume and the reservoir pressure for any of the simulated cases. When plotted in a pressure-volume diagram, hysteresis loops are found that are looped in a clockwise way indicating that the reservoir pressure is lower than the pressure associated with the change in volume. The reservoir-wave analysis leads to very high excess pressures, especially for the coarctation models, but to surprisingly little changes of the reservoir component despite the impediment of the buffer capacity of the aorta.

CONCLUSION

With the observation that reservoir pressure is not related to the volume in the aortic reservoir in systole, an intrinsic assumption in the wave-reservoir concept is invalidated and, consequently, also the assumption that the excess pressure is the component of pressure that can be attributed to wave travel and reflection.

Umbilical Artery Half-Peak Systolic Velocity Deceleration Time in Fetal Growth Restriction

Objective: To study the umbilical artery (UA) half-peak systolic velocity deceleration time (hPSV-DT) in pregnancies complicated by fetal growth restriction (FGR). Methods: The study included 266 singleton, high-risk pregnancies with an estimated fetal weight <10th percentile, which were examined between 24 and 40 weeks' gestation and delivered within a week from the last ultrasound evaluation. UA hPSV-DT was measured with Doppler ultrasound in the same wave used to measure the pulsatility index. UA hPSV-DT values were correlated with perinatal outcome. Results: UA hPSV-DT <5th percentile was found in 87 and 98% of fetuses with moderate and severe FGR, respectively. 94% of fetuses with a UA hPSV-DT <90 ms had poor perinatal outcome including perinatal death or prolonged admission to the neonatal intensive care unit. None of the fetuses had a UA hPSV-DT <70 ms. Perinatal death occurred in 39 fetuses; UA hPSV-DT was abnormal in all of them, with 95% of these fetuses having values of ≤120 ms. In the group of fetuses with absent/reverse end-diastolic velocity in the UA, the perinatal mortality rate was 51% for those with a UA hPSV-DT ≤90 ms and only 23% for those having a UA hPSV-DT >90 ms (p < 0.01). Conclusions: UA hPSV-DT seems to be a useful technique in the evaluation of pregnancies at risk for FGR and perinatal death. Additionally, hPSV-DT was shown to be a good predictor of perinatal death, with values of <90 ms corresponding to imminent risk of intrauterine demise and values of <70 ms being likely to be incompatible with intrauterine life.

Comparison of invasive and non-invasive pressure gradients in aortic arch obstruction

BACKGROUND

Aortic arch obstruction can be evaluated by catheter peak-to-peak gradient or by Doppler peak instantaneous pressure gradient. Previous studies have shown moderate correlation in discrete coarctation, but few have assessed correlation in patients with more complex aortic reconstruction.

METHODS

We carried out retrospective comparison of cardiac catheterisations and pre- and post-catheterisation echocardiograms in 60 patients with native/recurrent coarctation or aortic reconstruction. Aortic arch obstruction was defined as peak-to-peak gradient ⩾25 mmHg in patients with native/recurrent coarctation and ⩾10 mmHg in aortic reconstruction.

RESULTS

Diastolic continuation of flow was not associated with aortic arch obstruction in either group. Doppler peak instantaneous pressure gradient, with and without the expanded Bernoulli equation, weakly correlated with peak-to-peak gradient even in patients with a normal cardiac index (r=0.36, p=0.016, and r=0.49, p=0.001, respectively). Receiver operating characteristic curve analysis identified an area under the curve of 0.61 for patients with all types of obstruction, with a cut-off point of 45 mmHg correctly classifying 64% of patients with arch obstruction (sensitivity 39%, specificity 89%). In patients with aortic arch reconstruction who had a cardiac index ⩾3 L/min/m², a cut-off point of 23 mmHg correctly classified 69% of patients (71% sensitivity, 50% specificity) with an area under the curve of 0.82.

CONCLUSION

The non-invasive assessment of aortic obstruction remains challenging. The greatest correlation of Doppler indices was noted in patients with aortic reconstruction and a normal cardiac index.

Differential impact of local stiffening and narrowing on hemodynamics in repaired aortic coarctation: an FSI study

Even after successful treatment of aortic coarctation, a high risk of cardiovascular morbidity and mortality remains. Uncertainty exists on the factors contributing to this increased risk among which are the presence of (1) a residual narrowing leading to an additional resistance and (2) a less distensible zone disturbing the buffer function of the aorta. As the many interfering factors and adaptive physiological mechanisms present in vivo prohibit the study of the isolated impact of these individual factors, a numerical fluid-structure interaction model is developed to predict central hemodynamics in coarctation treatment. The overall impact of a stiffening on the hemodynamics is limited, with a small increase in systolic pressure (up to 8 mmHg) proximal to the stiffening which is amplified with increasing stiffening and length. A residual narrowing, on the other hand, affects the hemodynamics significantly. For a short segment (10 mm), the combination of a stiffening and narrowing (coarctation index 0.5) causes an increase in systolic pressure of 58 mmHg, with 31 mmHg due to narrowing and an additional 27 mmHg due to stiffening. For a longer segment (25 mm), an increase in systolic pressure of 50 mmHg is found, of which only 9 mmHg is due to stiffening.

Imaging of congenital heart disease in adults: choice of modalities

Major advances in noninvasive imaging of adult congenital heart disease have been accomplished. These tools play now a key role in comprehensive diagnostic work-up, decision for intervention, evaluation for the suitability of specific therapeutic options, monitoring of interventions and regular follow-up. Besides echocardiography, magnetic resonance (CMR) and computed tomography (CT) have gained particular importance. The choice of imaging modality has thus become a critical issue. This review summarizes strengths and limitations of the different imaging modalities and how they may be used in a complementary fashion. Echocardiography obviously remains the workhorse of imaging routinely used in all patients. However, in complex disease and after surgery echocardiography alone frequently remains insufficient. CMR is particularly useful in this setting and allows reproducible and accurate quantification of ventricular function and comprehensive assessment of cardiac anatomy, aorta, pulmonary arteries and venous return including complex flow measurements. CT is preferred when CMR is contraindicated, when superior spatial resolution is required or when "metallic" artefacts limit CMR imaging. In conclusion, the use of currently available imaging modalities in adult congenital heart disease needs to be complementary. Echocardiography remains the basis tool, CMR and CT should be added considering specific open questions and the ability to answer them, availability and economic issues.

Unilateral pulmonary artery branch stenosis: diastolic prolongation of forward flow appears to maintain flow to the affected lung if the pulmonary valve is competent

BACKGROUND

We sought to improve understanding of the diastolic prolongation of forward flow seen through a unilateral branch pulmonary artery (PA) stenosis.

METHODS AND RESULTS

Of patients studied by cardiovascular magnetic resonance (CMR) for congenital heart disease, we reviewed right and left PA flow to find 10 cases with a diastolic prolongation of flow in a stenosed branch PA. They were aged 20 years (median, range = 14-40 years, 7 males). Seven had transposition of the great arteries corrected by arterial switch (TGA-AS) and 3 had repaired tetralogy of Fallot (rToF). All had at least moderate unilateral stenosis and competent pulmonary valves. For comparison, we identified 10 patients with unilateral stenosis and at least moderate pulmonary regurgitation, 9 rTOF and 1 TGA-AS, aged 23.5 years (range = 14-42 years, 6 males). Flow in each PA was measured, and in 10 healthy volunteers aged 27 years (range = 20-42 years, 5 males). The curves of flow through stenosed and non-stenosed arteries were averaged for each patient group and compared with those from controls. In competent pulmonary valve patients, the minimum diameters of the stenosed versus non-stenosed branches were as follows (median [range]): 4 [3-8] mm versus 13.5 [10-28] mm, p<0.001, although their flows differed a little: 2.5 [1.5-6.8] L/min versus 3.2 [1.2-8.8] L/min, p=0.6. No diastolic tail was identifiable in the patients with unilateral PA stenosis and pulmonary regurgitation, where stenosed versus non-stenosed diameters were 7 [4-12] mm versus 20.5 [13-33] mm, p<0.001, and flows differed: 1.3 [0.4-2.9] L/min versus 3.8 [3.0-5.0] L/min, p<0.001. No controls showed stenosis or diastolic tail.

CONCLUSIONS

Beyond a competent pulmonary valve, flow through a unilateral PA stenosis, although limited in systole, can continue into diastole, maintaining flow to the lung.

Doppler echocardiographic indices in aortic coarctation: a comparison of profiles before and after stenting

Background

Diagnosis of aortic coarctation is important as it is a difficult condition to evaluate, especially in adults. A Doppler echocardiographic index could provide a simple tool to evaluate coarctation. This study was performed to compare Doppler echocardiographic profiles before and after stenting and to assess the diagnostic value of a complete list of echocardiographic indices for detecting aortic coarctation.

Methods

This prospective study was conducted on 23 patients with a diagnosis of aortic coarctation based on angiography. Echocardiographic assessment was done twice for all patients before and after stenting. Each time, two-dimensional and Doppler echocardiographic imaging modalities were performed and complete lists of indices were recorded for each case. After comparing the values of indices before and after stenting, diagnostic values of each index were calculated in order to diagnose significant coarctation.

Results

Twenty-three patients, including 16 males and seven females with a mean age of 26.14 ± 10.17 years, were enrolled in this study. Except for the mean velocity and mean pressure gradient of the abdominal aorta, the values of the other indices of the abdominal/descending aorta showed enough change after stenting to indicate significant diagnostic accuracy for detecting aortic coarctation. The velocity–time integral and the pressure half-time were among the indices with the highest accuracy rates for this purpose (all p < 0.001).

Conclusion

Post-stenting echocardiographic profiles could provide a reliable reference value of the normal aortic haemodynamics as a unique identification of each patient and it is presumed that these indices could be used as reliable indicators of response to treatment.

Mathematical, numerical and experimental study in the human aorta with coexisting models of bicuspid aortic stenosis and coarctation of the aorta

Coarctation of the aorta is an obstruction of the aorta and is usually associated with other concomitant cardiovascular abnormalities especially with bicuspid aortic valve stenosis. The objectives of this study are, (1) to investigate the effects of coarctation on the hemodynamics in the aorta to gain a better understanding of the cause of certain post-surgical coarctation problems, (2) to develop and introduce a new lumped parameter model, mainly based on non-invasive data, allowing the description of the interaction between left ventricle, coarctation of the aorta, aortic valve stenosis, and the arterial system.

Endovascular management of coarctation of the aorta

Untreated thoracic aortic coarctation leads to early death predominantly because of hypertension and its cardiovascular sequelae. Surgical treatment has been available for > 50 years and has improved hypertension and survival. More recently, endovascular techniques have offered a minimally invasive alternative to traditional open repair. Early and intermediate results suggest angioplasty and stenting have an important role in the management of aortic coarctation, particularly in adults and older children.

3D pulsatile flow in a curved tube with coexisting model of aortic stenosis and coarctation of the aorta

Coarctation of the aorta is a congenital heart disease defined as an obstruction of the aorta distal to the left subclavian artery (between the aortic arch and descending aorta). It is usually associated with other diseases such as bicuspid and tricuspid aortic stenosis. If the coarctation remains uncorrected it can lead to hypertension, left ventricular failure and aortic dissection. Numerous investigations pointed out that there is a relationship between the genesis and the progression of cardiovascular disease and the locally irregular flow occurring at the diseased zone. Therefore, to examine the relationship between arterial disease and hemodynamics conditions, detailed quantitative studies on flow dynamics in arterial models are clearly inquired. In this study we numerically investigate pulsatile blood flow in a simplified model of the aorta (curved pipe) with coexisting coarctation of the aorta and aortic stenosis. Three severities of aortic stenoses (0.61 cm(2), 1.0 cm(2) and 1.5 cm(2)) coexisting with aortic coarctations (50%, 75% and 90% by area) are investigated. An experimentally validated numerical model from literature is used and baseline results are validated against it. To ensure having a physiologically relevant model using this geometry, flow properties are set so that the Dean number falls in the physiological range for the aorta. The results show that the coexistence of these pathologies significantly modifies the flow in a curved pipe. The maximal velocity is shifted towards the outer wall and can reach values as high as 5m/s just downstream of the coarctation. The wall shear stress distribution is significantly modified compared to the normal, unobstructed case. Finally, a clinically significant pressure gradient is induced by the curvature of the tube (up to 36 mmHg). This can lead to an overestimation of the severity of the coarctation using catheterization.

Stenosis of the thoracic aorta in Williams syndrome

Williams syndrome (WS) is a multisystem congenital disorder affecting 1/8000 live births. Our objective was to review our experience with stenosis of the thoracic aorta (STA) in these patients. A retrospective review was undertaken of consecutive WS patients at The Children's Hospital of Philadelphia from January 1, 1980, through December 31, 2007. WS was diagnosed by an experienced medical geneticist and/or by fluorescence in situ hybridization. Stenosis was diagnosed with either echocardiography or cardiac catheterization. Freedom from intervention was determined using Kaplan-Meier analysis. From a total cohort of 270 patients, 37 (14%) patients with STA were identified and comprised the study group. Age at presentation was 2.1 + or - 4.0 years, and follow-up was 11.8 + or - 12.6 years (range 0-51). Long-segment STA was more common (89%) than discrete STA. Severity of STA was mild in 18, moderate in 10, and severe in 9 patients. Branch pulmonary artery stenosis was seen in 62% (23 of 37) of STA patients, and supravalvar aortic stenosis was seen in 54% (20 of 37) STA patients. Nine (24%) patients underwent intervention for STA: 8 cases were severe, and 1 case was moderate. Restenosis resulting in reintervention occurred in 5 of 9 (56%) patients, with 4 of 5 (80%) patients undergoing multiple reinterventions. Freedom from intervention was 89, 82, and 73% at 1, 5, and 20 years, respectively. One patient died. STA is common in WS and is generally the long-segment type. In patients with STA, interventions are common and usually occur by 5 years of age. Reintervention for STA occurs frequently.

Echocardiographic evaluation of pressure gradient across the stent in patients treated for coarctation of the aorta

OBJECTIVE

Stent placement has become a widely used method of treatment for coarctation of the aorta (COA). Our goal was to find echocardiographic indices that would correlate best with directly measured gradients across the coarctation stent.

MATERIAL AND METHODS

Pediatric patients with COA who underwent intra-aortic stent placement were evaluated. Patients with more than mild aortic insufficiency were excluded. Aortic pressures above and below the coarctation site were directly measured in the catheterization laboratory. Echocardiography was performed the next morning. Continuous and Pulse Doppler systolic velocity profiles proximal and distal to the stent were recorded. Statistical analysis included Pearson's correlation coefficients and linear regression between the directly measured pressure gradient and strongest correlated factor.

RESULT

Thirty-four patients (F : M = 15 : 19) were included in the study. The directly measured gradients (DPG) had only weak positive correlations with Doppler peak velocities (r = 0.38, P= .027) or pressure gradients (r = 0.37, P= .03) across the stent. However, there was a strong positive correlation of the directly measured gradients with the continuous wave peak systolic velocity half-time indexed to heart rate (T) (r = 0.62, P= .03), and with the squared early diastolic velocity (V(d) (2)) (r = 0.073, P < .0001). When these two parameters were combined, a linear regression equation DPG = 0.06T + 1.58 V(d) (2)- 8.05 showed very strong relations (r = 0.81, P < .0001). A simplified equation DPG = 1.98V(d) (2)+ 0.77 also accurately described the relations between the directly measured gradients and squared Doppler-measured early diastolic velocity (r = 0.71, P= .0002).

CONCLUSIONS

A simple echocardiographic index DPG = 1.98V(d) (2)+ 0.77, where DPG is the pressure gradient across the stent, and V(d) is the early Doppler diastolic velocity, accurately describes relations between the gradient across the stent and echocardiographic data and should be used for evaluation of patients with stent-corrected COA.

Abdominal aortic pulsed wave Doppler patterns reliably reflect clinical severity in patients with coarctation of the aorta

OBJECTIVE

There are situations in which standard echocardiography does not adequately define the aortic arch. We sought to determine what additional information could be gained by analyzing abdominal aortic Doppler flows in coarctation.

DESIGN

Previously recorded echocardiographic data were reviewed in 70 controls and 248 patients with coarctation, including abdominal aortic values for pulsatility indices, pulse delay, and presence of early diastolic reversal. Ability of these variables to distinguish controls from coarctation patients and to assess coarctation severity was assessed.

RESULTS

Corrected maximum instantaneous gradient and all abdominal aortic flow variables were associated with severity of obstruction. Early diastolic reversal was universally absent in significant coarctation. Threshold values for other parameters associated with significant obstruction were: corrected pulse delay >or=3.4 msec(1/2), pulsatility index <2.0, and systolic to diastolic velocity ratio <3.6. A combined abdominal aortic "variable" (absence of early diastolic reversal and corrected pulse delay >or=2.8 msec(1/2)) was found to be the best predictor of clinical coarctation status (positive predictive value = 93%, negative predictive value = 88%).

CONCLUSIONS

In the absence of a ductus arteriosus, abdominal aortic Doppler parameters can reliably predict the presence of significant coarctation. When early diastolic reversal was present, obstruction was always absent. Lack of early diastolic reversal with a prolonged pulse delay was the best predictor of significant obstruction. Abdominal aortic Doppler evaluation should become a routine part of the evaluation of patients with known or suspected coarctation.

Clinical and echocardiographic findings of pulmonary artery stenosis in seven cats

OBJECTIVES

Describe the clinical, electrocardiographic (ECG), radiographic and echocardiographic findings in cats with isolated pulmonary artery stenosis. Assess the usefulness of systolic and diastolic Doppler measurements at predicting stenosis severity.

BACKGROUND

Pulmonary artery stenosis is an infrequent congenital cardiac defect in humans that has not been reported in cats. In humans, pulmonary artery stenosis is usually seen in conjunction with other cardiac defects and may lead to clinical signs if severe.

ANIMALS, MATERIALS AND METHODS

Seven cats with pulmonary artery stenosis were retrospectively evaluated. Medical records, radiographs, ECGs, echocardiograms and angiocardiograms were reviewed. Severity of stenosis was assessed by two-dimensional and color Doppler echocardiographic evaluation and clinical findings. Peak systolic and diastolic gradients across the stenosis, and systolic and diastolic pressure decay half-times were graded using echocardiography. In addition, the duration of antegrade flow during diastole was subjectively assessed. Univariate analyses were performed to assess the best variable to predict stenosis severity.

RESULTS

Concurrent congenital defects were not identified. Only cats with severe obstruction showed clinical signs including exertional dyspnea and lethargy. Diastolic Doppler measurements were superior to systolic measurements at predicting severity of stenosis. Antegrade flow throughout diastole and/or a diastolic pressure half-time of >100 ms indicated severe obstruction. The prognosis for pulmonary artery stenosis appears to be good regardless of severity.

CONCLUSION

Among cats with pulmonary artery stenosis, clinical signs are uncommon and prognosis is good. Doppler assessment of diastolic flow appears to be superior to systolic flow at predicting severity.

Outcome after extended arch repair for aortic coarctation

OBJECTIVES

To assess survival and long term arch patency rates in a consecutive group of children after extended arch repair for coarctation of the aorta.

METHODS

Review of 191 consecutive children (154 (81%) under 1 year of age) operated on between 1990 and 2002 by a single surgeon using extended arch reconstructive techniques. For assessment of survival patients were divided into three groups: 1, coarctation alone, n = 104; 2, coarctation and ventricular septal defect, n = 38; and 3, coarctation in association with complex intracardiac anomalies, n = 49. A prospective and systematic clinical and echocardiographic evaluation of the aortic arch was undertaken.

RESULTS

Median time to follow up was 4.2 years (range 1-10.6 years). Overall actuarial survival was 92%, 88%, and 88% at two, five, and 10 years. Mortality was significantly higher in those patients with complex intracardiac anatomy. Arch obstruction recurred in seven of 165 (4.2%) patients: four of 139 (2.9%) term and three of 10 (30%) premature infants (p < 0.001).

CONCLUSIONS

Survival after extended arch reconstruction for coarctation is excellent. At long follow up recurrent arch obstruction is rare, with prematurity the only risk factor.

Doppler echocardiographic profile and indexes in the evaluation of aortic coarctation in patients before and after stenting

OBJECTIVES

We sought to assess the effect of successful stenting on the Doppler profile of aortic coarctation and to identify echocardiographic indexes that could be used for follow-up of such patients.

BACKGROUND

Doppler echocardiography demonstrates characteristic flow patterns in significant aortic coarctation.

METHODS

We undertook retrospective echocardiographic analyses before and at six to nine months after coarctation stenting in consecutive patients from 2002 to 2003. Peak systolic pressure gradient (SPG), diastolic velocity (DV), end-diastolic tail velocity (EDTV), systolic velocity half-time index (SVHTi) and diastolic velocity half-time index (DVHTi), and systolic pressure half-time index (SPHTi) and diastolic pressure half-time index (DPHTi) were measured. The severity of aortic coarctation was compared with cardiovascular magnetic resonance (CMR) imaging using the coarctation index (CoAi).

RESULTS

The patient cohort was divided into two groups: group 1 (13 patients; age 30 +/- 8 years), which consisted of patients with significant aortic coarctation treated with stenting, and group 2 (11 patients; age 39 +/- 16 years), which consisted of patients with previous surgical repair of aortic coarctation without evidence of re-coarctation. After stenting, there was significant reduction in SPG (p = 0.001), DV (p = 0.001), EDTV (p = 0.005), DVHTi (p = 0.001), and DPHTi (p = 0.001) values. In the patient group as a whole, there was a significant correlation between SPG and DV (r = 0.86; p < 0.001), EDTV (r = 0.80; p < 0.001), DVHTi (r = 0.56; p < 0.001), and DPHTi (r = 0.50; p = 0.002). In addition, DV >193 cm/s (100% sensitivity, 100% specificity) and diastolic/systolic velocity ratio >0.53 (100% sensitivity, 96% specificity) had high predictive values for severe aortic coarctation (CoAi <0.25).

CONCLUSIONS

After stenting, peak SPG, DV, and pressure half-time indexes (i.e., DVHTi and DPHTi) decreased significantly. These findings can confidently be used in the follow-up of coarctation patients after stenting, particularly in those with limited two-dimensional images.

Coarctation of the aorta: pre and postoperative evaluation with MRI and MR angiography; correlation with echocardiography and surgery

AIMS

To compare MRI and MRA with Doppler-echocardiography (DE) in native and postoperative aortic coarctation, define the best MR protocol for its evaluation, compare MR with surgical findings in native coarctation.

MATERIALS AND METHODS

136 MR studies were performed in 121 patients divided in two groups: Group I, 55 preoperative; group II, 81 postoperative. In group I, all had DE and surgery was performed in 35 cases. In group II, DE was available for comparison in 71 cases. MR study comprised: spin-echo, cine, velocity-encoded cine (VEC) sequences and 3D contrast-enhanced MRA.

RESULTS

In group I, diagnosis of coarctation was made by DE in 33 cases and suspicion of coarctation and/or aortic arch hypoplasia in 18 cases. Aortic arch was not well demonstrated in 3 cases and DE missed one case. There was a close correlation between VEC MRI and Doppler gradient estimates across the coarctation, between MRI aortic arch diameters and surgery but a poor correlation in isthmic measurements. In group II, DE detected a normal isthmic region in 31 out of 35 cases. Postoperative anomalies (recoarctation, aortic arch hypoplasia, kinking, pseudoaneurysm) were not demonstrated with DE in 50% of cases.

CONCLUSIONS

MRI is superior to DE for pre and post-treatment evaluation of aortic coarctation. An optimal MR protocol is proposed. Internal measurement of the narrowing does not correspond to the external aspect of the surgical narrowing.

Intraluminal aortoplasty vs. surgical aortic resection in congenital aortic coarctation. A clinical random study in pediatric patients

BACKGROUND

Our objective was to compare results of two therapeutic modalities to treat congenital aortic coarctation: intraluminal aortoplasty without endoluminal stent installation (patients in group A) vs. surgical aortic resection (patients in group B). Trans-coarctation gradient pressure was evaluated prior to and immediately after treatment. Re-coarctation, aneurysm formation, in-hospital morbidity and mortality, and complications related to treatment were also evaluated.

METHODS

A clinical, randomized, multicenter study was performed in pediatric patients with congenital aortic coarctation. Immediate and mid- to late therapeutic results were evaluated. With regard to statistics, we evaluated event variations by Kaplan-Meier model, nonparametric Wilcoxon test, Mann-Whitney U test, two-tailed Student t and chi-square tests, and Fisher analysis. Significance was considered relevant when p<0.05.

RESULTS

There were no differences in demographic variables, procedure failure, complications, mortality, or aortic aneurysm between groups A and B, respectively. Intraluminal angioplasty and surgical aortic resection were similarly effective in reducing trans-coarctation pressure gradient, as well as arterial systemic pressure. However, differences were found between groups A and B at follow-up. Group A showed higher re-coarctation (50 vs. 21%). Absence of peripheral arterial pulses in limbs was higher in group A (50 vs. 21%), as well as persistence of arterial hypertension (49 vs. 19%); these differences were significant (p<0.05). On the other hand, complications observed after surgical aortic resection were more serious than post-angioplasty complications, but these differences were not statistically significant.

CONCLUSIONS

Although re-coarctation and persistency of arterial hypertension were less frequent after surgical aortic resection, complications observed with this procedure are more serious than complications related to angioplasty, although these differences are not statistically significant.

Insights into the effect of aortic compliance on Doppler diastolic flow patterns seen in coarctation of the aorta: a numeric study

BACKGROUND

In the echocardiographic evaluation of coarctation of the aorta, the degree of antegrade diastolic flow (diastolic runoff) noted on spectral Doppler tracings traditionally was thought to be solely dependent on lesion severity. However, recent in vitro experiments suggest the presence of this spectral Doppler pattern is as much related to the severity of coarctation as it is with changes in aortic compliance. Using state-of-the-art, multidisciplinary, numeric analysis tools, the purpose of this study was to investigate the specific fluid and wall mechanics present in coarctation of the aorta to further understand these relationships.

METHODS

Three computational numeric models of coarctation were developed with high, low, and no wall compliance. Flow simulations were run representing high- and low-flow states.

RESULTS

In both the low- and high-flow states, the degree of diastolic runoff increased with increasing vessel compliance. The high compliance model had larger changes in aortic dilatation in the precoarctation region compared with the low compliance model.

CONCLUSIONS

Increased aortic compliance brings about greater dilatation of the precoarctation aorta in systole, resulting in a persistence of stored upstream energy. This stored energy, released downstream in diastole as the precoarctation aortic walls contract, leads to increased degrees of diastolic runoff. Numeric methods offer a unique perspective into the mechanisms behind such clinical measures.

Spectrum of reoperations after repair of aortic coarctation: importance of an individualized approach because of coexistent cardiovascular disease

OBJECTIVE

To determine the indications for and spectrum of late reoperations in adults who had previously undergone coarctation repair.

PATIENTS AND METHODS

We reviewed clinical, cardiac catheterization, and echocardiographic data and criteria for reoperation, surgical procedures, and outcome in 43 patients who underwent 54 reoperations between 1972 and 1996.

RESULTS

Of the reoperations for recoarctation or associated cardiovascular disease (or both), 20% were performed in asymptomatic patients and 80% in symptomatic patients. Associated cardiovascular disease included bicuspid aortic valve in 36 patients (84%), aortic arch hypoplasia in 12 (28%), true or false aortic aneurysm in 6 (14%), mitral valve disease in 6 (14%), and subvalvular aortic stenosis in 5 (12%). Surgical procedures included 22 recoarctation repairs and 32 other cardiovascular interventions. Simultaneous repair of recoarctation and associated cardiovascular disease was performed as a single-stage repair in 5 reoperations through a median sternotomy using an extra-anatomic, ascending-to-descending aortic bypass, with no complications. One patient died (surgical mortality, 1.9%) of preexisting severe pulmonary vascular obstructive disease.

CONCLUSIONS

After coarctation repair, associated cardiovascular diseases are the most common cause for reoperation. An individualized surgical approach is important and may range from valve replacement or recoarctation surgery to extra-anatomic bypass combined with other cardiovascular procedures, enabling simultaneous repair of recoarctation and associated lesions. Despite complex surgical techniques and multiple reoperations, morbidity and mortality were low in our series.

Predictors of aneurysmal formation after surgical correction of aortic coarctation

OBJECTIVES

We sought to identify the predictors of aneurysmal formation after surgical correction of aortic coarctation.

BACKGROUND

In 9% of patients, aneurysms develop late after corrective surgery of coarctation of the aorta, with a 36% mortality rate if left untreated. However, the predictors of postsurgical aneurysmal formation are unknown.

METHODS

Of 25 aortic aneurysms requiring corrective surgery 152 +/- 78 months after the initial coarctation repair, 8 were located in the ascending aorta (type A) and 17 at the site of previous repair (local type). Seventy-four patients without progression of the aortic diameter within 189 +/- 71 months after coarctation repair were used for categorical data analysis in an attempt to identify the predictors of postsurgical aneurysmal formation.

RESULTS

Advanced age at coarctation repair (p = 0.004) and patch graft technique (p < 0.0005) independently predicted local aneurysmal formation. Type A aneurysm was univariately associated with the presence of a bicuspid aortic valve (p = 0.02), advanced age at coarctation repair (p = 0.044) and a high preoperative peak systolic pressure gradient of 74 +/- 21 mm Hg (p = 0.041). Conversely, multivariate analysis confirmed only the presence of a bicuspid aortic valve (p = 0.015) as an independent predictor of type A aneurysm. Receiver operating characteristic curve analysis revealed that 72% of patients with a postsurgical aneurysm had an operation at age 13.5 years or more, whereas 69% with no postsurgical aneurysm had an operation at a younger age.

CONCLUSIONS

Use of the patch graft technique and late correction of coarctation can predict aneurysmal formation at the site of coarctation repair, although patients with a bicuspid aortic valve may be at risk for an aneurysm developing in the ascending aorta, particularly after late repair of aortic coarctation with high preoperative pressure gradients.

Collateral flow in coarctation of the aorta with magnetic resonance velocity mapping: correlation to morphological imaging of collateral vessels

PURPOSE

To correlate quantification of collateral flow in aortic coarctation with the morphological visualization of the collateral vessels and to compare different approaches to measurement of collateral flow.

MATERIALS AND METHODS

Thirteen children with coarctation were examined with T1-weighted spin-echo (T1-W SE) imaging and 3D contrast-enhanced magnetic resonance angiography (MRA). MR velocity mapping was performed at four levels in the descending aorta.

RESULTS

The flow immediately above and below the coarctation did not differ significantly. Measuring within the coarctation resulted in flow overestimation. The increase of flow from proximal to distal aorta was 12 +/- 21% in patients with no or uncertain collaterals and 69 +/- 55% in patients with pronounced collaterals. Spin-echo images and MRA were comparable in visualizing collateral vessels. The visual estimation of collaterals correlated reasonably well with flow quantification MR velocity mapping.

CONCLUSION

Collateral flow assessment with MR velocity mapping is an accurate technique for evaluating the hemodynamic importance of a coarctation and is recommended if abundant collaterals are not visualized with spin echo or MRA.

Limitations of Doppler echocardiography for the post-operative evaluation of aortic coarctation

Doppler blood flow measurements and derived pressure differences, through the Bernoulli equation, are used in the diagnosis of aortic coarctation, a congenital stenosis distal to the left subclavian artery. Doppler velocities remain elevated at the coarctation site after successful repair of coarctation, leading to high Doppler derived pressure differences without significant arm-leg pressure differences. We studied this apparent contradiction of two diagnostic methods, in vivo using patient and control data, and in vitro using a hydraulic model. Clinical and echocardiographic data from 31 patients, aged 13.0 +/- 4.0, 10.5 +/- 4.7 yr after coarctectomy by end-to-end anastomosis, and 18 age-matched healthy subjects were reviewed. Doppler peak velocities at the aortic isthmus were elevated in patients (2.2 +/- 0.4 vs. 1.2 +/- 0.2m/s, P < 0.001), corresponding to significant Doppler differences (20 +/- 7 mmHg), however, without significant arm-leg pressure differences. In all patients, a mild anatomic stenosis could still be observed. Local stiffness was increased. The hypothesis that the less distensible surgical scar in post-coarctectomy patients leads to a significant dynamic obstruction in systole was validated in a latex model of the aorta. Rigid rings (0.5-1.5 cm), matching the unloaded aortic diameter, were mounted around the aorta. Under loading conditions, Doppler peak velocities increased by 40 +/-7%, yielding Doppler differences of 21 +/- 3 mmHg, without a significant pressure drop. An alternative expression to calculate pressure differences, using both velocity and geometric information, was validated in the model. In conclusion, post-operatively, Doppler velocities remain elevated due to a mild anatomical and significant dynamic narrowing, but the specific geometry, resembling a tubular hypoplasia rather than an abrupt stenosis, permits an almost complete pressure recovery explaining the occurrence of Doppler differences in disagreement with the negligible arm-leg pressure difference.

Fixed region of nondistensibility after coarctation repair: in vitro validation of its influence on Doppler peak velocities

After coarctectomy, local loss of distensibility is noted in addition to mild anatomic narrowing. We hypothesize that the increased Doppler peak velocities measured at the aortic isthmus in these patients partly reflect obstruction secondary to the stiff surgical scar. The hypothesis was studied in a pulsatile hydraulic model. Thirty-one patients (13.0 +/- 4.0 years of age), 10.5 +/- 4.7 years after coarctectomy by end-to-end anastomosis, were studied clinically and echocardiographically. Indexes of distensibility were calculated. The effect of isolated increased stiffness was studied in vitro with a stiff and a compliant 1:1 scale latex model of the aorta mounted in a pulsatile full-scale circulation loop. Local stiffening was obtained by a rigid ring mounted around the aorta, fitted to the dimension of the unloaded aorta. For different pressure and flow regimens, pressures and Doppler velocities were measured across the ring. Mean peak velocities at the surgical scar were 2.2 +/- 0.4 m/s. Mild anatomic stenosis was present. All distensibility indexes indicated locally increased stiffness (P <.001). In the stiff latex model, Doppler peak velocities increased from 1.89 +/- 0.04 m/s to 2.32 +/- 0.06 m/s (P <.03); in the compliant model, from 1.15 +/- 0.03 m/s to 1.79 +/- 0.05 m/s (P <.001). The increase of Doppler peak velocities depends on model compliance only and is independent of flow rate, length of the noncompliant segment, and viscosity of the perfusion fluid. Velocities do not change when semicircular stiffening is applied. We have demonstrated in vitro that isolated local nondistensibility leads to vessel narrowing during vascular distension. The relative contribution of local scar stiffness in the increase of Doppler peak velocities after coarctectomy was hereby assessed.

Coarctation of the aorta in adults: surgical results and long-term follow-up

BACKGROUND

The aim of this retrospective study was to determine the impact of coarctation surgical repair on arterial blood pressure in adults more than 20 years of age.

METHODS

Thirty-five adults (23 men), mean age 28.1 +/- 5.7 years (range, 21 to 52 years), underwent coarctation surgical repair between 1977 and 1997. All patients had preoperative hypertension. Mean systolic blood pressure was 178 +/- 37 mm Hg (range, 110 to 230 mm Hg). Thirty-three patients were taking at least one hypertension medication at the time of operation. All patients had preoperative catheterization and angiography (mean gradient across the coarctation was 62 +/- 27 mm Hg [range, 32 to 130 mm Hg]). Operative technique was resection and end-to-end anastomosis for 30 patients, resection with Dacron (C. R. Bard, Haverhill, MA) graft for 4 patients, and a prosthetic bypass graft for 1 patient. There were no hospital deaths and no late morbidity.

RESULTS

All patients were reviewed. Follow-up was 165 +/- 56 months (range, 25 to 240 months). Of the 35 patients with preoperative hypertension, 23 were normotensive (systolic blood pressure < or = 140 mm Hg, diastolic blood pressure < or = 90 mm Hg) with no medication. Twelve patients were receiving medication: 6 required single-drug therapy and 6 patients required two drugs. Exercise testing was performed at an average of 6 +/- 4 months after repair and revealed hypertensive response to exercise in 8 of the 23 patients who were normotensive at rest and without medication. There were no recoarctation or repeat operations. Six aortic valve diseases were observed: three aortic incompetences (two bicuspid valves) treated by two valve replacements and one Bentall procedure, and three aortic stenoses (two valve replacements). No patient had evidence of a cerebrovascular accident.

CONCLUSIONS

Surgical repair of coarctation in adults has proved to be an effective procedure and significantly reduces arterial hypertension. However, long-term surveillance is mandatory and should include exercise testing to identify patients with potential hypertension.

Subclavian flap angioplasty: does the arch look after itself?

OBJECTIVES

We sought to assess the early and long-term results of subclavian flap angioplasty in neonates and infants, with particular attention to growth of the hypoplastic arch.

METHODS

A retrospective analysis of 185 consecutive patients who underwent subclavian flap angioplasty between 1974 and 1998 was carried out. The patients included 125 neonates and 60 infants, with a median age of 18 days. Sixty-six (36%) patients had an additional ventricular septal defect, 41 (22%) patients had aortic arch hypoplasia diagnosed preoperatively, 141 (76%) had an associated patent ductus arteriosus, and 41 (22%) had additional complex heart disease. Follow-up was with transthoracic Doppler echocardiography in all patients.

RESULTS

The early mortality was 3%. Recoarctation, defined as a Doppler gradient of 25 mm Hg or more, occurred in 11 (6%) patients at a median follow-up of 6.2 years (6.2 +/- 4.6 years). This included 4 of the 41 patients in whom arch hypoplasia was diagnosed preoperatively. There were no complications with the left arm. By multivariate analysis, risk factors for death were determined to be residual arch hypoplasia and low birth weight. The only risk factor for recoarctation was persistent arch hypoplasia after surgical treatment. However, angiographic imaging of the aorta showed that recoarctation was not due to a hypoplastic transverse arch, and it was probably at the site of ductal tissue. Survival at 5 and 10 years was 98% and 96%, respectively. Freedom from reoperation for recoarctation at 2 years was 95%, and at 5, 10, and 15 years, it was 92%.

CONCLUSIONS

Subclavian flap repair remains an effective technique for repair of aortic coarctation with excellent results and low mortality. In the majority of patients, arch hypoplasia regresses after this procedure.

Effect of aortic compliance on Doppler diastolic flow pattern in coarctation of the aorta

The spectral Doppler pattern at the site of an aortic coarctation (CoA) generally displays increased maximal velocity (Vmax) during systole with a slow velocity decay, resulting in the characteristic "sawtooth" pattern. If there is rapid velocity decay, the obstruction is often judged to be mild. The purpose of this study was to investigate if velocity decay is affected by proximal aortic compliance (C(p)). The relation between the velocity decay measured from the Doppler pattern and C(p) was studied with the use of an in vitro pulsatile flow model. The time (tau) between Vmax and 33% Vmax was the measure of velocity decay. The C(p) was varied from 0.7 to 2.6 mL/mm Hg for each of 4 levels of CoA severity. The various obstructions produced a Vmax range of 2.7 to 5.5 m/s. There was a positive linear relation between tau and C(p) (r(2) = 0.76). For a low C(p) (compliance = 0.7 mL/mm Hg), velocity decay was rapid (tau = 0.2 to 0.3 seconds) with no diastolic gradient. For equivalent obstructions, a high C(p) (2.6 mL/mm Hg) produced a persistent diastolic gradient and slow velocity decay (tau = 0.5 to 0.6 seconds). The Doppler pattern across a CoA is affected by C(p). Therefore, the absence of a sawtooth pattern should not exclude the diagnosis of significant CoA obstruction.

Quantitative echocardiographic characterization of abdominal aortic pulsatility in children with coarctation

Obstructed blood flow due to aortic coarctation leads to a pressure drop and loss of the pulse wave distal to the stenosis. This can be observed by echocardiography as typically decreased pulsatility of the abdominal aorta after cardiac systole. Our study intended to quantitatively describe abnormal abdominal aortic pulsatility in children with coarctation. A standardized M-mode echocardiographic study of the abdominal aorta was prospectively performed with measurements of minimum and maximum abdominal aortic diameters and the corresponding time intervals during the cardiac cycle. Of these measurements the percent increase in aortic diameter was calculated and this increase was indexed to a unit of time. A total of 50 children were studied: 27 had angiographically proven severe coarctation (19 unoperated and 8 operated children with recurrent coarctation) with a mean minimum aortic lumen of 32+/-6% of the prestenotic aortic lumen. A total of 23 healthy children were studied as a control group. Children with significant coarctation differed from normals in all parameters evaluated. Two calculated values, the percent increase in aortic diameter (5-25% in patients and 27-50% in normals) and the percent increase per unit of time (18-108%/s in patients and 154-288%/s in normals) allowed for a clear discrimination between patients and normals with no overlap of individual values. Quantitative characterization of abnormal pulsatility of the abdominal aorta due to the loss of pulse wave pressure clearly discriminated children with angiographically proven significant coarctation from normal controls.

[Echocardiographic evaluation in unoperated congenital heart disease in adults]

Echo and Doppler echocardiographic procedures have gained special importance in the diagnostics of congenital diseases in adults. These procedures permit detailed visualization of the pathomorphology of the heart as well as reliable evaluation of the hemodynamic changes. There are differentiated indications for the various procedures, such as transthoracic and transesophageal echocardiography, Doppler and color-Doppler echocardiography, contrast echocardiography and 3-dimensional echocardiography. This article discusses the opposition of the various echo and Doppler echocardiographic procedures with respect to the diagnostics of the most frequent non-operated congenital diseases in adults. The pathomorphology of the various congenital diseases will be summarized and then the important echocardiographic criteria presented which are decisive for the diagnostic procedure. In simple congenital malformation of cardiac valves, such as bicuspid aortic valve (Figure 1: aortic ring abscess), pulmonary valve stenosis (Figure 2), Ebstein's anomaly (Figure 3) or malformations of the mitral valve (Figure 4: cleft in the anterior mitral cusp), the diagnosis can often be made using transthoracic echo and Doppler echocardiography, and the severity of the defect determined. However, the sonographic conditions, especially in adults, are frequently too limited to permit recognition of detailed smaller changes, so that transesophageal examination is required to finally confirm the diagnosis in these patients. In the diagnostics of diseases of the left ventricular outflow tract and the thoracic aorta, such as subvalvular aortic valve stenosis (Figure 5), the sinus of Valsalva aneurysm or the coarctation of the aorta (Figure 6), the left ventricular outflow tract can be evaluated morphologically from a transthoracic procedure and the accelerations of flow can be recorded by continuous wave Doppler. If there is no sclerosis of the fibrous membrane, these can often not be depicted by transthoracic procedures, so that a supplementary transesophageal examination is meaningful. This is required in any case for diseases of the descending thoracic aorta. In the case of congenital lesions, such as atrial septal defects (Figure 7: anomalous pulmonary venous return, Figure 8: 3-dimensional visualization of an atrial septal defect, Figure 9: sinus venosus defect), ventricular septal defect or a patent ductus arteriosus Botalli (Figure 10), color-Doppler and contrast echocardiography have become especially important. Transesophageal examination is also indicated for these congenital diseases for direct depiction of the defect as well as for precise evaluation of the shunt. Moreover, in atrial septal defects, it has been shown that a 3-dimensional echocardiography provides additional advantage with respect to spatial relationship of the defect to the other cardiac structures, as well as presenting dynamic changes during a heart cycle. Extensive knowledge of complex congenital heart disease, such as tetralogy of Fallot (Figure 11), complete transposition of the great arteries, congenitally corrected transposition of the great arteries (Figure 12), the double-outlet right ventricle, truncus arteriosus communis, the cor triatriatum, tricuspid atresia (Figure 13) or the univentricular heart (Figure 14) usually requires performance of a transthoracic echo- and Doppler echocardiographic examination to assess the pathomorphological changes and to examine hemodynamics. In the majority of patients, supplementary transesophageal echocardiography and an echo contrast examination are important. Initial examinations using 3-dimensional echocardiography are very promising in this connection and with respect to the exact spatial presentation of pathoanatomical structures.

Congenital Anomalies of the Aortic Arch

Congenital anomalies of the aortic arch can occur either in isolation or in conjunction with other intracardiac defects. This review will examine congenital aortic arch anomalies as if they occur in isolation, with the awareness that intracardiac defects often coexist. The three general classes of abnormalities to be reviewed are: (1) abnormal connections between the aorta and pulmonary arterial system; (2) aortic arch obstructions; and (3) defects in the formation of the aortic arch typified by right aortic arches, vascular rings, and cervical aortic arches. (ECHOCARDIOGRAPHY, Volume 13, March 1996)

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.

Transesophageal echocardiographic assessment of aortic coarctation using color, flow-directed Doppler sampling

We report the use of color, flow-directed transesophageal Doppler in the evaluation of aortic coarctation. Transesophageal echocardiography (TEE) was used to define the aortic shelf in two adults with mild and moderate postductal coarctation, respectively. The color mosaic pattern aided in identification of the coarctation location and orifice diameter. Continuous wave and pulsed cursors were steered to provide sampling parallel to the color jet direction and gradients calculated by the modified Bernoulli formula, excluding prestenotic velocities. Measured pressure gradients were equivalent to those determined at catheterization. We conclude that color, flow-directed TEE Doppler sampling can aid in the identification and characterization of adult patients with aortic coarctation.

Evaluation of aortic coarctation after surgical repair: role of magnetic resonance imaging and Doppler ultrasound

OBJECTIVE

To compare the usefulness of magnetic resonance imaging (MRI) and Doppler ultrasound with that of cross sectional echocardiography and oscillometric blood pressure measurement for the evaluation of aortic coarctation after surgical repair.

DESIGN

Prospective study. Aortic diameters measured by cross sectional echocardiography, MRI, and angiography (selected cases) and functional data determined by physical examination, oscillometric blood pressure measurement, and continuous wave Doppler.

SETTING

Tertiary referral centre.

PATIENTS

40 patients aged 2-28 years (mean 10.6 years) who had had surgical correction of aortic coarctation (mean follow up 5.7 years).

RESULTS

In all patients MRI gave diameter measurements of the aortic arch and the thoracic aorta whereas in half of them cross sectional echocardiographic measurement of the isthmic region failed. The correlation coefficient for aortic diameters measured by MRI and angiography was 0.97 and that between MRI and echocardiography was 0.89. Peak velocities in the descending aorta correlated better with residual narrowing of the aortic isthmus or distal aortic arch or both than systolic blood pressure gradients between the upper and lower limbs. A peak velocity of < 2 m/s in the descending aorta during systole excluded important restenosis. Prolongation of anterograde blood flow during diastole always indicated a morphological abnormality--either important restenosis or aneurysmal dilatation.

CONCLUSIONS

MRI was better than cross sectional echocardiography for imaging the aortic arch after coarctation repair and measuring its diameter. Peak velocity in the descending aorta correlated better with residual stenosis than did the systolic blood pressure gradient between the upper and lower limbs and this index could be used to indicate a need for MRI.

Juxtaductal aortic atresia masquerading as coarctation

Two cases of juxtaductal aortic atresia diagnosed as coarctation on clinical and Doppler echocardiographic grounds are presented. The misleading nature of the Doppler flow velocity characteristics in this condition is discussed and raises questions as to the source of these flow velocities in coarctation.

Evaluation of anatomical obstruction by Doppler echocardiography and magnetic resonance imaging in patients with coarctation of the aorta

OBJECTIVE

To evaluate a new Doppler echocardiographic index of obstruction in patients with native coarctation or recoarctation.

PATIENTS

32 patients (mean age 20, range 3 months--50 years).

METHODS

Magnetic resonance imaging (MRI) was used to investigate the descending aorta. The cross sectional area of the obstruction was compared with the area of the abdominal aorta as an index of obstruction (CoA index). Doppler echocardiography was used to record the velocities in the coarctation jet and in the abdominal aorta. According to the continuity equation the ratio of these velocities should equal the ratios of the cross sectional areas. The gradients and diastolic half time of the Doppler curve were calculated.

RESULTS

There was a close correlation between the MRI index of obstruction and the Doppler velocity ratio (r = 0.92). The sensitivity and specificity of this ratio in detecting a CoA index equal to or less than 0.25 were better than those obtained with gradients only or the combination of gradients and diastolic half time.

CONCLUSION

The new Doppler velocity ratio correlated closely with an anatomical index of obstruction. It was easy to record in most patients and it avoided difficulties about the choice of instantaneous or peak to peak gradients and whether or not to subtract proximal velocities for the calculation of gradients.

Noninvasive diagnosis of coarctation of the aorta in the presence of a patent ductus arteriosus

Although the diagnosis of coarctation of the aorta in the full-term neonate is straightforward when no ductus arteriosus is present, identification of coarctation of the aorta when a ductus arteriosus is patent can be difficult. A patent ductus arteriosus is frequently found in association with coarctation of the aorta, and it may remain open for many days. Thus a reliable method to rapidly identify coarctation of the aorta would obviate the need for cardiac catheterization or an in-hospital observation period until the ductus arteriosus closes spontaneously. Echocardiographic/Doppler examination of 19 consecutive full-term neonates with a birth weight of > 2.9 kg, who subsequently underwent surgical repair of coarctation of the aorta, were reviewed. Fourteen patients with similar weights, a patent ductus arteriosus, and a normal aortic arch were matched for comparison. Based on the findings, the following diagnostic criteria for coarctation of the aorta are suggested: isthmic diameter less than or equal to 3 mm or isthmus equal to 4 mm together with the Doppler finding of continuous antegrade flow in the isthmal segment. Coarctation of the aorta in the full-term neonate can be ruled out when the flow within the ductus arteriosus is exclusively from aorta to pulmonary artery or when the isthmic diameter is equal to or greater than 5 mm.

Coarctation of the aorta life and health 20-44 years after surgical repair

OBJECTIVE

To examine the health and lifestyle of a group of patients who had repair of coarctation of the aorta 20-44 years ago (these were the first such operations in the United Kingdom) and to see how the results would influence current management strategies.

DESIGN

Attempts were made to contact all patients by questionnaire. They were then requested to attend for a clinical examination.

SETTING

Patients had their initial surgery at the Westminster Hospital (by Charles Drew) and the follow up examination at the same hospital.

PATIENTS

149 operations were performed. 70 of the 106 patients presumed to be alive were traced and 62 replied. 42 attended for examination. Only patients with the diagnosis of simple coarctation were included. Some patients had had coincidental ligation of a patent ductus arteriosus but none had any other cardiac abnormality requiring surgical or medical treatment. Those who died during the follow up period were described in paper by Bobby et al (Br Heart J 1991;65:271-6).

MAIN OUTCOME MEASURES

Current symptoms and life situations, evidence of cardiac disease, further cardiac surgery, current and retrospective blood pressures, and Doppler echocardiographic examination.

RESULTS

29 (69%) had cardiovascular disorder. Doppler echocardiography did not show previously unrecognised major recoarctation. 19 (46%) had hypertension at follow up and there was evidence of enlargement of the aortic root or arch in seven (16%) patients, who tended to have had surgery at a later age. No evidence of cerebrovascular accident was found.

CONCLUSIONS

In this group of patients with surgically repaired simple coarctation, late morbidity (particularly aortic aneurysm, aortic valve disease, and ischaemic heart disease) was common. The incidence of intracranial haemorrhage seemed to have been reduced by surgical repair. The integrity of the surgery remained good. Many patients did not have any regular cardiovascular review. Long-term anxiety related to early surgical experiences was evident. Even after apparently successful surgical repair of aortic coarctation. It would be prudent for all patients to have long-term review.

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.