Determination of right ventricular pressure in the presence of a ventricular septal defect using continuous wave Doppler ultrasound

Ventricular septal defect Doppler peak gradient underestimates right ventricular systolic pressure in the presence of right bundle branch block

Estimation of the right ventricular systolic pressure (RVSP) using echocardiographically derived maximal instantaneous gradient across the ventricular septal defect is a well-utilized tool, which can potentially underestimate the RVSP in patients with conduction abnormalities as such its utility in these patients is questionable.

Transesophageal echocardiography (TEE) in congenital heart disease with focus on the adult

Remarkable innovations in medical and surgical approaches over the past several decades now allow for correction of major cardiac defects in children, even in early infancy. These advances have provided for survival of many pediatric patients with congenital heart disease into adulthood. Although transthoracic echocardiography remains the primary imaging technique for the characterization of simple and complex congenital cardiovascular malformations in the pediatric and adult age groups, high-resolution transesophageal imaging has markedly expanded the anatomic and hemodynamic assessment in these patients. The benefits of this imaging approach apply particularly to those with challenging or limited transthoracic examinations or poorly characterized congenital cardiovascular malformations. The utility of TEE in defining the anatomy of the usual spectrum of congenital cardiac malformations is well established. The transesophageal approach has been shown to provide additional diagnostic information over conventional transthoracic imaging for specific structural cardiac anomalies and in the perioperative setting, the opportunity for confirmation of preoperative diagnoses, and modification of the surgical plan if new or different pathology is identified. This imaging modality also may reliably provide for immediate detection of suboptimal surgical repairs and significant postoperative residua, potentially improving the efficacy of the surgical intervention. This accounts for the vital role of this technology in perioperative management and integration into the standard of care in many congenital heart centers. The usefulness of TEE also has been documented during diagnostic and therapeutic cardiac catheterizations of patients with structural cardiac anomalies, allowing for safer and more effective application of these technologies. The experience supports the use of TEE as a useful approach in the surveillance of the adult with operated and unoperated congenital heart disease.

Echocardiography's Role in Cardiogenic Shock After Acute Myocardial Infarction

Cardiogenic shock is an emergent condition that requires immediate diagnosis. Assessment and evaluation of potential complications that often accompany shock must also be made. These complications may be seen individually or in concert. Echocardiography has emerged in the last two decades as the single most important procedure in this effort. The authors reviewed four cases of cardiogenic shock after acute myocardial infarction: two with ventricular septal rupture, one with papillary muscle rupture, and one with severe global left ventricular dysfunction. Each patient was evaluated emergently with echocardiography. Results were compared with electrocardiography, arteriography, right heart catheterization studies, and surgical reports.

Noninvasive estimation of right ventricular systolic pressure in postinfarction ventricular septal rupture: an assessment of two Doppler echocardiographic methods

OBJECTIVE

To evaluate the diagnostic accuracy of Doppler echocardiography in the assessment of right heart hemodynamics and the diagnosis of pulmonary hypertension in patients with ventricular septal rupture due to acute myocardial infarction.

DESIGN

A prospective, echocardiographic and right-heart catheterization study.

SETTING

Medical intensive care unit (ICU) of a university hospital.

PATIENTS

Twelve consecutive patients admitted to the ICU with the diagnosis of ventricular septal rupture in the setting of acute myocardial infarction. Confirmation of diagnosis was made during surgery (11 patients) or by autopsy (one patient).

INTERVENTIONS

All patients were examined by two-dimensional and Doppler echocardiography on admission and subsequently underwent bedside right-heart catheterization.

MEASUREMENTS AND MAIN RESULTS

After identification and localization of the rupture site by two-dimensional echocardiography and/or color flow Doppler mapping, the maximal flow velocity of the transseptal jet was measured by continuous-wave Doppler and was used to calculate the peak interventricular pressure gradient by the modified Bernoulli equation. This value was subtracted from the systolic arterial blood pressure value to estimate right ventricular systolic pressure. The values obtained correlated well with catheter-derived measurements (r2 = .71; p = .001). Furthermore, in eight (67%) patients, right ventricular systolic pressure could also be determined by Doppler interrogation of the tricuspid regurgitant jet. Direct comparison of the results of the two echocardiographic methods yielded a good correlation (r2 = .66; p = .016).

CONCLUSION

Doppler examination of the transseptal and tricuspid regurgitant jets is applicable to patients with ventricular septal rupture for rapid, noninvasive prediction of right ventricular hemodynamics.

Doppler echocardiographic evaluation of ventricular septal defects in adults

Ventricular septal defects account for 10% to 15% of all congenital heart defects observed in adults. The type of defects observed tend to fall at the extreme ends of the spectrum: small restrictive defects with minimal shunts, and large nonrestrictive defects associated with severe occlusive pulmonary vascular disease. Doppler echocardiography has evolved into a powerful diagnostic modality that comprehensively evaluates the anatomical and pathophysiological consequences of a ventricular septal defect. The spectrum of findings caused by ventricular septal defects is the subject of this review.

Estimation of right ventricular pressure in children by thallium-201 myocardial imaging using single-photon emission computed tomography

Thallium-201 myocardial imaging using single-photon emission computed tomography was performed to estimate right ventricular (RV) systolic pressure in 34 children (aged 4.1 to 16.1 years, mean 7.9 +/- 2.9). Acquisition of the images was performed using a semicircular arc of 180 degrees. On a short-axis slice, a line drawn perpendicular to the ventricular septum so as to cross the RV free wall showing maximum uptake was defined as the region of interest. Thallium-201 counts in regions of interest over both RV and left ventricular (LV) free walls were measured. The ratio of RV-to-LV peak thallium-201 counts was compared with RV peak systolic pressure and the ratio of RV-to-LV peak systolic pressure measured at cardiac catheterization. Both RV peak systolic pressure and the ratio of RV-to-LV peak systolic pressure correlated well with the ratio of RV-to-LV peak thallium-201 counts (r = 0.95 and 0.96, respectively). The ratio of RV-to-LV peak thallium-201 counts greater than or equal to 0.45 could predict RV pressure overloading with a sensitivity of 92%, and a specificity of 88%. Thus, the quantitative analysis of thallium-201 myocardial imaging using single-photon emission computed tomography permits the noninvasive and accurate estimation of RV systolic pressure in children.

A new method for noninvasive estimation of ventricular septal defect shunt flow by Doppler color flow mapping: imaging of the laminar flow convergence region on the left septal surface

An accurate but simple and noninvasive method for quantifying flow across a ventricular septal defect has yet to be implemented for routine clinical use. A region of flow convergence is commonly imaged by Doppler color flow mapping on the left septal surface of the ventricular septal defect, appearing as a narrowed region of laminar flow with aliased flow velocities entering the orifice. If the first aliasing region represents a hemispheric isovelocity boundary of a surface of flow convergence and all flow at this surface crosses the ventricular septal defect, the flow through the defect can be estimated by using the radius (R), measured from the first alias to the orifice, and the Nyquist limit (NL) velocity (the flow velocity at the first alias). Doppler color flow imaging was performed in 18 children with a single membranous ventricular septal defect undergoing cardiac catheterization at a mean age of 29.8 months (Group I). Indexes of maximal flow rate across the defect were developed from either the radius or the area, obtained by planimetry, of the first alias, based on Doppler color flow images. All indexes were corrected for body surface area and compared with shunt flow (Qp-Qs) and pulmonary to systemic flow ratio (Qp/Qs) determined at cardiac catheterization. Doppler color flow indexes derived from images of flow convergence in both the long-axis (n = 15) and oblique four-chamber (n = 10) views correlated closely with Qp/Qs (r = 0.71 to 0.92) and Qp - Qs (r = 0.69 to 0.97).(ABSTRACT TRUNCATED AT 250 WORDS)

Doppler assessment of the interventricular pressure drop in patients with ventricular septal defects

Doppler ultrasound was used to assess the pressure drop between the ventricles in 109 infants and children (61 less than two years old) with a ventricular septal defect who underwent cardiac catheterisation. The pressure in both ventricles was measured at catheterisation in 103 patients either simultaneously through two catheters (41) or with a single catheter withdrawn across the septum or removed from one ventricle to the other (62). When pressure was measured simultaneously with two catheters (41 patients) the peak to peak and instantaneous gradients showed a maximum difference of 20 mm Hg with levels within 10 mm Hg of each other in 36. Comparison of the difference in the gradients with the average of the measurements demonstrated a tendency for Doppler to underestimate the difference when it was high (greater than 50 mm Hg) and overestimate it when it was low. A Doppler estimate of a low pressure difference between the ventricles indicates pulmonary arterial hypertension and a high one low pulmonary artery pressure, but in the intermediate group Doppler is as yet not sufficiently sensitive to allow selection of those patients who require further investigation and possible operation. Doppler ultrasound was found to be a sensitive method of detecting a very small ventricular septal defect. Thus although Doppler is a very useful means of assessing and following patients with a ventricular septal defect, further studies are required to determine its exact place in clinical practice.

Quantitative applications of Doppler cardiography in congenital heart disease

Doppler ultrasound has rapidly become a valuable tool in the noninvasive investigation of cardiac hemodynamics. Although based on secure principles, accurate application of this methodology to quantitative measurements necessitates a thorough understanding of both Doppler physics and instrumentation. Over the past several years a large body of clinical and animal data verifying the accuracy of Doppler determination of pressure and flow data at various sites in the cardiovascular system, as well as the potential sources of error in acquisition and interpretation of blood velocity recordings, has been published. Quantitative use of Doppler in congenital heart disease, with emphasis on limitations of existing studies and issues particular to this patient population, is reviewed.

Doppler echocardiography

The advancements in Doppler methodology in the past decade have dramatically changed the way we assess children with heart disease. Techniques to determine pressures, gradients, shunt flows, and regurgitant lesions have shifted the noninvasive studies into areas that were strictly the venue of catheterization a decade ago. The more recent color Doppler developments take the 2DE image one step further by providing some of the flow visualization previously available only through angiography. When applied to appropriate clinical settings Doppler methodology will continue to provide us with increasingly sophisticated and precise definitions of intracardiac physiology.