One and a half ventricle repair in adults: postoperative hemodynamic assessment using phase-contrast magnetic resonance imaging.

BACKGROUND: One and a half ventricle repair (1½ repair) strategy has been used for patients with a hypoplastic or dysfunctional right ventricle (RV), or both. We sought to assess the postoperative hemodynamics of 1½ repair using phase-contrast magnetic resonance imaging (PC-MRI). METHODS: Ten adults, 9 with Ebstein's anomaly and 1 with tricuspid stenosis, underwent 1½ repair (median age at operation, 42.4 years). The azygos vein was left open in all patients on 1½ repair to prevent severe postoperative central venous hypertension. Postoperative PC-MRI studies were performed to measure blood flow to the ascending aorta (QAsc-Ao), the main pulmonary artery (QMPA), the superior vena cava (SVC) (QSVC), and the branch pulmonary arteries and veins. From these values, blood flow to the upper compartment of the body (QUC), right ventricular volume unloading effect (QMPA/QAsc-Ao), proportion of blood flow to the upper compartment of the body (QUC/QAsc-Ao), and venous return to arterial forward flow ratio of the upper compartment of the body (QSVC/QUC) were calculated. Two patients also underwent preoperative PC-MRI. RESULTS: On PC-MRI, QMPA/QAsc-Ao, QUC/QAsc-Ao, and QSVC/QUC were 0.58 to 0.84 (median, 0.67), 0.19 to 0.36 (median, 0.27), and 0.47 to 1.57 (median, 0.93, lower than 1.0 in 7 patients), respectively. In 2 patients who had preoperative and postoperative PC-MRI, QUC/QAsc-Ao decreased from 0.26, 0.32 to 0.21, 0.28, respectively. CONCLUSIONS: After 1½ repair, right ventricular volume unloading was effective in all patients, but intercaval collateral veins (ie. QSVC/QUC<1) appeared to develop in most of the patients. Furthermore blood flow to the upper compartment of the body appeared to diminish, presumably due to postoperative elevation of central venous pressure.

Cardiovascular magnetic resonance imaging in the assessment of carcinoid heart disease.

Carcinoid disease arises from a low-grade neuroendocrine tumour derived from serotonin-producing enterochromaffin cells. It is the most common tumour affecting the small bowel. The majority of patients who progress to carcinoid syndrome develop cardiac disease selectively involving the right side of the heart, whereas left heart disease is unusual. The most common cause of death is dilatation and dysfunction of the right ventricle. Right ventricular dysfunction is largely secondary to pathological endocardial fibrosis of the tricuspid and pulmonary valves, presenting with regurgitation and stenosis. Average survival falls to only 11 months with the onset of symptoms, but recent evidence suggests that survival can be improved by early surgery in selected individuals. This article reviews the particular role that cardiovascular magnetic resonance imaging has in the management of carcinoid heart disease.

Valvular and hemodynamic assessment with CMR.

Cardiovascular magnetic resonance is able to provide a comprehensive assessment of valvular and hemodynamic function, including quantification of valve regurgitation and other flows, and accurate cardiac volumes and mass for assessing the effect on both ventricles. Combined with the ability to image all areas of the heart (including difficult areas, such as the right ventricle and pulmonary veins), it is an ideal technique for investigating patients who have heart failure in whom these areas need to be examined.

Diagnosis and assessment of valve stenosis and regurgitation and coarctation of the aorta with Doppler ultrasound.

With the use of Doppler ultrasound localized increases in blood flow velocities can be recorded and used to diagnose obstructions to blood flow. From the increase in maximal velocities the pressure drop across an obstruction can be calculated, both the peak instantaneous and the mean pressure drop. Regurgitations are diagnosed by recording reversal of blood flow across the valve. Semi-quantitative evaluation of the degree of regurgitation can be made by using both jet width, extension and intensity, as well as increase in forward flow velocity, reversal of flow in great vessels and influence on pressures. In coarctation of the aorta localized increase in velocity in the descending aorta can be shown and the pressure drop can be calculated. In some, more than one level of obstruction can be shown. In neonates the presence of a patent ductus arteriosus may mask the obstruction and a significant pressure drop may become apparent only when narrowing or closure of the duct occurs.

Noninvasive assessment of valve lesions with Doppler ultrasound.

Noninvasive assessment of valvular lesions with Doppler echocardiography is based on determination of velocities of blood flow in the region of cardiac valves, adjacent cardiac chambers and in the large vessels. Obstructions lead to an increase in the velocity of flow in the region of the stenosis which can be registered with the Doppler technique. Through application of the Bernoulli equation, from the maximal velocity, the pressure gradient across the stenotic valve can be calculated. Additionally, the severity of the stenosis is reflected in the temporal course of the velocity curve of the jet through the stenosed valve. For this purpose, in mitral stenosis, the pressure half-time is employed and, in aortic stenosis, the peak of the velocity curve during systole is used. The severity of tricuspid and pulmonic stenosis can also be classified with a method analogous to that used in obstruction of the left heart. The diagnosis of valvular incompetence is based on the detection of regurgitant flow. The extent of regurgitant flow into the proximal cardiac chamber enables semiquantitative classification of severity. The intensity of the jet through the incompetent valve is also indicative of the size of the regurgitant volume. Similar to that in obstructive lesions, the temporal course of the velocity curve is also related to the severity. In association with high-grade regurgitant lesions, there is a premature decrease in the velocity curve. Additionally, the severity of aortic regurgitation can be assessed on the basis of the extent of regurgitant flow in the descending aorta or the subclavian arteries.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of valvular heart disease by Doppler echocardiography.

Doppler echocardiography provides direct hemodynamic data that are often complementary to those demonstrated by M-mode and two-dimensional echocardiographic imaging. This relatively new noninvasive technique has a number of important uses in patients with valvular heart disease. In both adults and children, Doppler measures of peak flow velocity through a stenotic valve allow accurate prediction of the pressure gradient across the valve, and the technique has particular promise for screening patients with suspected aortic or pulmonic stenosis. In patients with mitral stenosis but parasternal short-axis images of limited quality, Doppler velocity measures can provide novel data about the pressure gradient and mitral orifice area. Doppler techniques can also provide direct evidence for or against the presence of valvular regurgitation, and several approaches allow clinically useful estimation of the extent of aortic, mitral, or tricuspid regurgitation. In patients with known disease of one cardiac valve, Doppler is accurate for evaluating the integrity of a second valve. Finally, Doppler techniques have great promise for defining the nature, and perhaps the severity, of suspected prosthetic valve malfunction. Hence, we believe that Doppler echocardiography should become a routine part of the noninvasive evaluation of patients with known or suspected valvular heart disease.

Non-invasive diagnosis and assessment of tricuspid regurgitation and stenosis using one and two dimensional echo-pulsed Doppler.

Twenty normal subjects and 82 patients with valvular heart disease, whose lesions were independently assessed either by cardiac catheterisation and/or at operation, were studied using the pulsed Doppler technique combined with either one or two dimensional echocardiography. Of these, 41 patients had tricuspid lesions, including 40 with regurgitation and nine with stenosis. The tricuspid analogue flow velocity trace and the Doppler frequency spectrum (time interval histogram) were recorded. Characteristic differences were found between the records from subjects with and without tricuspid lesions. In subjects with tricuspid regurgitation there was a systolic negative wave on the analogue velocity display and broadening of the time interval histogram. In subjects with tricuspid stenosis there was an abnormal pattern, and significantly increased duration of the diastolic wave on the analogue velocity trace, again with broadening of the time interval histogram. Sensitivity and specificity ranged between 85 and 95%. The calculated ratio between the measured amplitudes of the systolic and diastolic waves correlated well with independently performed grading of the regurgitation on a three point scale in 85% of cases. Grading of the severity of tricuspid stenosis on a three point scale based on studies of the diastolic Doppler velocity anomalies was the same in 85% of cases as the grading based on established invasive techniques. The addition of two dimensional echocardiography to the pulsed Doppler technique increased the sensitivity for mild lesions.