Computer-assisted assessment of the kinetic function of disk-type artificial heart valves.

A simple and accurate computer simulation method was developed to evaluate the geometrical parameters of disk-type artificial heart valves from cinefluorographic recordings. In vitro valve models with preset occluder angles were used to test the accuracy of the method. Linear regression analysis produced slope 1.00055 and intercept 0.0402, with r = 0.999. In vivo reproducibility was tested through repeated measurements, taken several weeks apart, of OMS valves in situ. Regression with slope 1.02 and intercept -0.95, r = 0.95 were found.

MR imaging in congenital heart disease: where is the leading edge?

MRI has proved to be a useful tool in the evaluation of congenital heart disease. Two types of information can be gleaned from this new imaging modality. The first has to do with the acquisition of anatomical details which are best retrieved from "static" scanning using a low field strength. We have found magnetic resonance to be superior to angiocardiography and/or echocardiography in gathering anatomical information in the following situations: congenital heart defects having giant compartments; conotruncal malformations; and assessment of surgical results. Secondly, physiological information can be obtained using "dynamic" or cine magnetic resonance imaging, utilizing a high field strength.

Reconstruction of the four basic cardiac projections from magnetic resonance images: a new aspect.

From 3D MR scans, the authors have constructed 2D "silhouettes" that correspond to standard radiographic views of the heart. These images explicitly demonstrate the relationship of the surface anatomy to the internal anatomy of the heart and serve to indicate what chambers contribute to the heart borders seen on radiographs. The findings depart from conventional wisdom in at least four respects, including: the left atrium contributes to the left heart border in a frontal radiograph in only a minority of subjects, in steep RAO and lateral radiographs, the right ventricle does not always form the anterior heart border, in left anterior oblique radiographs greater than 30 degrees, the anterior heart border is formed predominantly by the right ventricle, and the left ventricle extends more craniad along the posterior margin of the heart than expected.

Takayasu's arteritis. Protean manifestations.

An adolescent girl presented with fever, weight loss, and headache. Despite extensive diagnostic studies, the diagnosis of Takayasu's arteritis was made only after she developed bruits and diminished pulses. Although the initial manifestations of Takayasu's arteritis are often protean and confusing, characteristic clinical and radiographic findings develop after the onset of vascular insufficiency. The chest radiograph may provide an early clue to diagnosis, which can be confirmed by arterial digital subtraction aortography. Physicians should consider Takayasu's arteritis in the differential diagnosis of prolonged fever or weight loss in young females because treatment appears to be more effective when started early.

MR imaging of Ebstein anomaly: results in four cases.

We performed ECG-gated MR imaging in four patients (4 months-15 years old), all of whom had a previously diagnosed severe form of Ebstein anomaly of the tricuspid valve. The goal was to study the anatomy of this congenital heart defect with MR imaging. The axial and coronal scans provided the best details. All characteristic abnormalities were seen well: the maintained proximal and faulty distal attachment of the anterior tricuspid leaflet, the absence of both septal and posterior tricuspid leaflets, the size and delineation of the anatomically atrialized chamber of the right ventricle, and the small, compressed trabecular portion with the markedly dilated pumping outflow tract of the right ventricle proper. Our results suggest that MR may furnish valuable information in patients with Ebstein anomaly when echocardiography is either inconclusive or technically difficult to perform.

A persistent fifth aortic arch in man: a double-lumen aortic arch (presentation of a new case and review of the literature).

Persistent fifth aortic arch manifested as a double-lumen aortic arch (DLAA) is a rare anomaly. We present such a case with transposition of the great arteries, ventricular septal defect (VSD), and pulmonary atresia. Review of the eight previously published cases indicates relatively frequent association of DLAA with preductal coarctation of the aorta. We attempt to explain the coexistence of this lesion with DLAA. We also discuss evidence supporting derivation of the inferior channel of the DLAA from the embryologic fifth aortic arch.

MR imaging of the central pulmonary arterial tree in conotruncal malformation.

Successful MR imaging of the central pulmonary arterial tree was performed in four cases of conotruncal malformation and in one case of pulmonary arterial banding. Angiography performed near the time of MR imaging in three cases and 15 years earlier in two other cases did not visualize the central pulmonary arterial tree. Multiplanar imaging was necessary to fully visualize the anatomy of complex congenital defects of the pulmonary arterial tree; the choice of imaging plane varied depending on the portion of the pulmonary artery to be evaluated.

Unusual pulmonary lesion of vascular origin: a noninvasive diagnostic approach.

Despite the lack of pathologic confirmation, we believe that we are reporting an isolated pulmonary artery branch stenosis with poststenotic dilatation. The differential diagnosis of a solitary pulmonary lesion should include this unusual entity. Digital subtraction angiography offers a safe, minimally invasive way to confirm this anomaly.

Intracardiac tumor: an unusual case of myocardial ischemia.

We have presented an unusual case of right ventricular tumor mimicking myocardial ischemia. Tumor invasion of deeper structures of the heart is rare, and we think the ECG and enzyme changes in our patient were due to invasion of the ventricular septum by the tumor.

Calcified thrombus of the inferior vena cava in transposition of the great vessels.

Calcified thrombus of the inferior vena cava (IVC) in children is an entity usually not associated with significant complications. The possibility of pulmonary embolism from the soft thrombus, however, has been suggested but never reported. We give an account of a child with transposition of the great vessels who suffered embolization from a calcified thrombus in the IVC that entered the systemic circulation.

Mirror-image right aortic arch: a proposed mechanism in symptomatic vascular ring.

We describe a rare case of right aortic arch with mirror-image branching and a left ductus arteriosus that form an anomalous vascular ring. The unusual feature of this symptomatic vascular ring is presence of a left (posterior) circumflex descending aorta in lieu of an aortic diverticulum which usually represents the posterior element of the vascular ring associated with right aortic arch and mirror-image branching. This we believe is the seventh reported case of Type 1 right aortic arch and only the third such case with a left circumflex descending aorta. Accurate diagnosis was made by barium esophagogram and angiocardiogram and was confirmed surgically. We propose a new theory as to why some vascular rings formed by the right aortic arch are symptomatic while others are not.

Renal vein renin sampling in essential hypertension using hydralazine and the tourniquet test.

The results of renal vein renin sampling were assessed in 40 patients who had uncomplicated essential hypertension. All had normal creatinine clearance, intravenous pyelography, and arteriography. During sampling, renin release was stimulated in 29 patients with intravenous hydralazine and in 11 with the tourniquet blood trapping test. Simultaneous sequential renal vein samples were drawn over a 30-minute period. Positive renal vein renin ratios (greater than or equal to 1.5) were seen in 52% of the hydralazine group at 0 minutes and in 69% post-hydralazine. In the tourniquet group, 27% had a positive ratio at 0 minutes as compared with 64% post-tourniquets. A significant difference was found in renal vein plasma renin activity between the two kidneys (p greater than or equal to .0001). The asymmetry of renal vein renin activity and the large renal vein renin ratios in these two groups suggest the presence of true differences in renin secretion. These differences may be due to focal nephrosclerosis. The therapeutic significance of a positive renal vein renin ratio in the hypertensive patient should be determined in conjunction with arteriography.

Intrarenal aneurysm of the renal artery in children.

Two children with hypertension had intrarenal aneurysms in the renal artery. In both children, renovascular hypertension was documented by renal vein renin assay showing elevated renin secretion from the involved kidney and suppression of renin secretion from the contralateral kidney. Transcatheter embolization of a segmental artery cured the hypertension in one case. A nephrectomy performed in the other case, because of multiple intrarenal aneurysms, was curative. Intrarenal renal artery aneurysms are an uncommon cause of renovascular hypertension in children. The aneurysms may be mycotic or congenital in origin, or secondary to diffuse vasculitis. Although spontaneous resolution of the aneurysms may occur when due to vasculitis, treatment of most aneurysms is usually necessary. Transcatheter embolization of solitary aneurysms is an attractive alternative to partial nephrectomy, since it allows maximal preservation of renal parenchyma with minimal morbidity.