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

Non-Invasive Assessment of Intravascular Pressure Gradients: A Review of Current and Proposed Novel Methods

Invasive catheterization is associated with a low risk of serious complications. However, although it is the gold standard for measuring pressure gradients, it induces changes to blood flow and requires significant resources. Therefore, non-invasive alternatives are urgently needed. Pressure gradients are routinely estimated non-invasively in clinical settings using ultrasound and calculated with the simplified Bernoulli equation, a method with several limitations. A PubMed literature search on validation of non-invasive techniques was conducted, and studies were included if non-invasively estimated pressure gradients were compared with invasively measured pressure gradients in vivo. Pressure gradients were mainly estimated from velocities obtained with Doppler ultrasound or magnetic resonance imaging. Most studies used the simplified Bernoulli equation, but more recent studies have employed the expanded Bernoulli and Navier⁻Stokes equations. Overall, the studies reported good correlation between non-invasive estimation of pressure gradients and catheterization. Despite having strong correlations, several studies reported the non-invasive techniques to either overestimate or underestimate the invasive measurements, thus questioning the accuracy of the non-invasive methods. In conclusion, more advanced imaging techniques may be needed to overcome the shortcomings of current methods.

The effectiveness of stenting of coarctation of the aorta: a systematic review

AIMS

Stent placement as treatment for coarctation of the aorta (CoA) has become a more common choice in the last 20 years. Clinical results of CoA stenting are usually reported in small retrospective case series. This systematic review provides an overview of clinical experience with stenting for CoA.

METHODS AND RESULTS

A systematic review of the reports published between January 1990 and December 2014 after stenting a CoA was performed with a focus on relief of obstruction and lowering of blood pressure. Study and patient characteristics were extracted, as well as pre- and post-stenting aortic diameter in mm, systolic pressure gradient (SPG) and pre- and post-stenting systolic blood pressure (mmHg), periprocedural and follow-up complications. Forty-five articles met the inclusion criteria. Three outcomes were extracted from the articles - aortic diameter, systolic pressure gradient and blood pressure. Diameter increased from 6.4 mm (5.6, 7.3) to 15.1 mm (14.5, 15.7), pressure gradients decreased from 40 mmHg (35, 42) to 4 mmHg (3, 5) and systolic blood pressure decreased from 153 mmHg (148, 158) to 132 mmHg (127, 136). Stent migration was the most common periprocedural complication (2.4%), and mortality was low (0.4%).

CONCLUSIONS

Stenting is an effective treatment with regard to immediate relief of obstruction and direct lowering effect on blood pressure. However, there is a lack of evidence regarding late effectiveness concerning durable blood pressure lowering, and limited information on periprocedural and late complications. This observation calls for a systematic and longer prospective follow-up of patients after CoA stenting.

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.

Prevalence and long-term predictors of left ventricular hypertrophy, late hypertension, and hypertensive response to exercise after successful aortic coarctation repair

Controversial data exist about the long-term results of aortic coarctation (AC) repair. This study explored the prevalence and predictors of left ventricular (LV) hypertrophy, late hypertension, and hypertensive response to exercise in 48 subjects (age, 15.1 ± 9.7 years) currently followed in the authors' tertiary care hospital after successful AC repair. Data on medical history, clinical examination, rest and exercise echocardiography, and ambulatory blood pressure monitoring were collected. The time from AC repair to follow-up evaluation was 12.9 ± 9.2 years. The prevalence of LV hypertrophy ranged from 23 to 38 %, based on the criteria used to identify LV hypertrophy, and that of concentric geometry was 17 %. One sixth of the patients without residual hypertension experienced late-onset hypertension. One fourth of those who remained normotensive without medication showed a hypertensive response to exercise. Age at AC repair was the strongest independent predictor of LV hypertrophy, defined using indexation either for body surface area (odds ratio [OR], 1.03; p = 0.0090) or for height(2.7) (OR 1.02; p = 0.029), and it was the only predictor of late hypertension (OR 1.06; p = 0.0023) and hypertensive response to exercise (OR 1.09; p = 0.029). The risk of LV hypertrophy was 25 % for repair at the age of 3.4 years but rose to 50 and 75 % for repair at the ages of 5.9 and 8.4 years, respectively. Similar increases were found for the risk of late-onset hypertension and hypertensive response to exercise. A considerable risk of LV hypertrophy, late hypertension, and hypertensive response to exercise exists after successful AC repair. Older age at intervention is the most important predictor of these complications.

The role of echocardiography in the early diagnosis of the complications of endovascular repair of blunt aortic injury

PURPOSE

Endovascular repair of traumatic aortic injury has been associated with severe procedural complications, including endoleaks, coverage of the left subclavian artery, stent collapse, access complications, and questionable durability. Echocardiography has proven to be a valuable tool in the intraoperative detection of these complications. In the current study, we report on the use of echocardiography as an early postoperative diagnostic technique for the evaluation of endovascular stent graft positioning in the intensive care setting.

METHODS

From January 2005 to January 2009, 14 patients who underwent endovascular repair of a blunt aortic injury were admitted in our intensive care unit. Transesophageal and/or transthoracic echocardiography were used as first-line diagnostic tools in the assessment of the endovascular graft position.

RESULTS

Twenty-eight percent of patients (4 of 14) developed a pressure gradient between upper and lower limbs (greater than 50 mm Hg), which presented with persistent hypertension, requiring antihypertensive therapy in high doses and difficult weaning. In all 4 patients, stent graft malposition was identified using echocardiography. The diagnosis was verified by computed tomography and aortography.

CONCLUSION

Noninvasive echocardiographic monitoring proved to be a valuable tool in the early diagnosis of postoperative stent graft malalignment. To our knowledge, this is the first time that echocardiography is described in the relevant literature as an early diagnostic technique in this setting.

Pediatric interventional cardiology: 2009

PURPOSE OF REVIEW

Pediatric interventional cardiology has evolved quite dramatically over the past few decades and now, in 2009, the published literature continues to evolve new percutaneous strategies for managing patients with congenital heart disease, both simple and complex. Our goal for this review was to highlight new techniques and the new devices available to the pediatric interventional cardiologist, and to review the outcomes from past endeavors.

RECENT FINDINGS

Manuscripts published in the past year continue to demonstrate innovation; indicating an exciting and increasing experience of transcatheter treatment of septal communications using either new occluder devices or novel techniques. Bioabsorbable devices and percutaneously implanted valves are leading examples of technological improvements and creativity that will ultimately improve patient outcomes while minimizing invasiveness. Reports on procedural outcomes show technically safe early follow-up, with promising mid-term and long-term results for balloon valvuloplasty, balloon atrial septostomy and pulmonary artery stent implantation. As well, fetal and hybrid interventions have become important new arenas for the pediatric interventionist.

SUMMARY

Pediatric interventions have grown far beyond the early stages of the 1980s as mid-term and long-term outcome data are being reported, and many previously insurmountable hurdles have been overcome by developing new strategies and devices.