[Radioisotopes for the study of right and left ventricular function in surgically treated Fallot's tetralogy]

Radio-nuclide angiography after surgical correction of tetralogy of Fallot (TOF) allows measurement of the ejection fraction, especially of the right ventricle, under basal conditions and on effort, parameters which are difficult to measure by other non-invasive methods. Twenty-two children with a mean age of 12.6 +/- 6.9 years who had undergone complete correction of TOF at a mean age of 6.7 +/- 3.8 years underwent Technetium 99m blood pool studies at equilibrium. The results were compared with those of a control group of children with a mean age of 10.2 +/- 3.3 years. No first passage studies were performed because the frequency of postoperative pulmonary regurgitation does not allow quantification of the shunt due to a possible residual ventricular septal defect. No significant difference was found between the patients and control subjects at rest: LV ejection fraction (66.7 +/- 11 p. 100 vs 63 +/- 7.7 p. 100), RV ejection fraction (50.3 +/- 7.2 p. 100 vs 54 +/- 14.8 p. 100). The response to effort of the right and left ventricles depends on the type of exercise. The LV ejection fraction increased normally whilst the RV ejection fraction showed a lot of individual variation. Equilibrium radionuclide angiography was also used to calculate the ratio of right to left end diastolic ventricular volumes. This ratio indicates the degree of RV diastolic overload when LV diastolic volumes are normal, which was the case in our series. The study group showed a significant increase in this ratio compared to control subjects (1.94 +/- 0.65 vs 1.2 +/- 0.23). Exercise radionuclide imagery should provide more accurate assessments of the surgical results and prognosis of these children providing standardised protocols are used. These investigations are best performed in patients over 15 years old, so as to avoid the technical difficulties related to small size. Resting studies are possible at all ages.

[Outcome of children operated on for congenital cardiopathy before 2 years of age. Foreseeable sequelae at adulthood]

A brief description is presented of the long-term follow-up of four commonly encountered cardiopathies undergoing early surgical correction. Sequelae are not increased and probably even less frequent when compared to children undergoing surgery after two years of age. It is still too early, however, to establish whether or not certain manifestations, such as rhythm or conduction disturbances and ventricular dysfunction will develop at a later date. The prognosis of coarctation of the aorta depends to a great extent on other associated lesions which can become serious over time and require additional surgical procedures. In the past, early surgery for large ventricular septal defects was poorly tolerated, but now the prognosis is particularly favorable. Persistent hemodynamic abnormalities such as stenoses of the pulmonary outflow tract can worsen the prognosis in tetralogy of Fallot. In addition, it is especially important to recognize subsequent ventricular dysrhythmias due to their potentially serious nature. The most common procedures for transposition of the great arteries consist of auricular transposition of the venous returns which may later cause rhythm disturbances or venous stenoses. The long-term functional capacity of the right ventricle as a pump for the systemic circulation is not known. A general outline of follow-up care is presented.

[Evaluation of the pulmonary artery and its branches by two-dimensional echocardiography in the tetralogy of Fallot and pulmonary atresia in infants. Angiocardiographic correlation and therapeutic implications]

Twenty-two infants aged 5 days to one year (mean: 3.8 months), consisting of 17 with tetralogy of Fallot and 5 with pulmonary atresia-ventricular septal defect, were prospectively investigated by two dimensional echocardiography (2 D echo) in order to evaluate the severity of the impairment of the pulmonary outflow tract and value of 2 D echo in the preoperative evaluation. Right pulmonary artery (PA), observed by angiography in 20 patients, was correctly recorded and could be measured in all cases (20/20), whereas the left PA was seen in 19 patients (19/20). Pulmonary confluence was recognized in 20/20 cases and its absence in 2 cases. In one patient without pulmonary confluence, a large substituted systemic vessel was mistaken for right PA. Echo established in the 22 patients (100%) the presence (17 cases) or absence (5 cases) of continuity between the right ventricle and the PA. Echo demonstrated 2 out of the 3 stenoses of the branches found by angiography. The internal diameter of PA measured by echo, ranging from 3 to 9 mm, was compared with angiographic measurements. A significant linear correlation was observed for each diameter (ring, trunk and branches) between the two techniques. However, echo slightly under-estimated the angiographic diameters. These results show that 2 D echo is a reliable method to determine the severity of impairment of the pulmonary outflow tract in infants with tetralogy of Fallot. They suggest that is may be used to guide the choice of surgical procedure and is adequate, in selected patients, to carry out a palliative intervention without open surgical procedure.

Tumor uptake of high and low molecular weight fractions from 67Ga-citrate labelled blood plasma

Blood plasma from tumor-bearing rats was incubated with 67Ga-citrate, and two fractions of high molecular weight (proteins) and low molecular weight were isolated by dialysis and by gel-filtration chromatography. Both fractions showed a different in vivo uptake by DS-sarcoma-bearing animals, the high molecular weight fraction being accumulated to a lesser extent. Compared to 67Ga-citrate the low molecular weight fraction showed a different uptake which for most tissues was significatively higher. This behavior suggests the presence of 67Ga in chemical forms other than citrate in the low molecular weight fraction. The lower uptake of the blood protein fraction is discussed.

Tumor Uptake of High and Low Molecular Weight Fractions from 67Ga-Citrate Labelled Blood Plasma

Blood plasma from tumor-bearing rats was incubated with 67Ga-citrate, and two fractions of high molecular weight (proteins) and low molecular weight were isolated by dialysis and by gel-filtration chromatography. Both fractions showed a different in vivo uptake by DS-sarcoma-bearing animals, the high molecular weight fraction being accumulated to a lesser extent. Compared to 67Ga-citrate the low molecular weight fraction showed a different uptake which for most tissues was significatively higher. This behavior suggests the presence of 67Ga in chemical forms other than citrate in the low molecular weight fraction. The lower uptake of the blood protein fraction is discussed.

On the mechanisms of 67Ga and 59Fe uptake by tumors

The uptake of 67Ga-citrate and 59Fe-citrate in the presence or absence of gallium and iron carriers, was studied on DS-sarcoma-bearing rats. Differences of uptake pattern were observed with both radionuclides. The tumor uptake of 67Ga is greatly affected by both carriers while 59Fe uptake is independent of the presence of carriers. The role of isotopic dilution, ionic competition, and the probable presence of high and low affinity binding sites in this phenomenon are discussed.

67Ga and 59Fe uptake by tumor cells treated with hyperthermia or hyperthermia plus lanthanum

The uptake of 67Ga-citrate and 59Fe-citrate by tumor cells treated with hyperthermia or with hyperthermia plus lanthanum has been studied. The comparison of these results with ion flux determinations (42K) appears to indicate that hyperthermia alone or combined with lanthanum modifies the ionic permeability of the plasma membrane. This phenomenon seems to be responsible for the increased accumulation of 67Ga and 59Fe.

On the Mechanisms of 67Ga and 59Fe Uptake by Tumors

The uptake of 67Ga-citrate and 59Fe-citrate in the presence or absence of gallium and iron carriers, was studied on DSsarcoma-bearing rats. Differences of uptake pattern were observed with both radionuclides. The tumor uptake of 67Ga is greatly affected by both carriers while 59Fe uptake is independent of the presence of carriers. The role of isotopic dilution, ionic competition, and the probable presence of high and low affinity binding sites in this phenomenon are discussed.

Ionic competition and 67Ga in vivo accumulation

The effect of several citrates of trivalent cations on 67Ga citrate uptake by tumor-bearing animals has been studied. A relationship between the ionic size of the simultaneously injected cation and the 67Ga uptake inhibition indicates that the cation characteristics (ionic radius and electrical charge) seem to play the most important role in this radioactivity accumulation. The apparent agreement of this phenomenon with the isomorphous replacement hypothesis is discussed.