[Factors influencing the occurrence of delayed potentials after myocardial infarction. A multivariate study]

Delayed or late potentials after myocardial infarction is a marker of the risk of severe ventricular arrhythmias. We looked for the factors favorising the appearance of these potentials in 208 consecutive patients (172 men, 36 women) admitted to hospital for primary myocardial infarction. Coronary angiography, evaluation of the left ventricular ejection fraction and signal averaged electrocardiography were performed in all patients who were then divided into two groups (Group I: patients with delayed potentials; Group II: patients without delayed potentials). A multivariate analysis of 7 different clinical and paraclinical parameters possibly related to delayed potentials was undertaken. The overall incidence of delayed potentials was 20%. The coronary artery responsible for the infarct was occluded in 79% of patients in Group I and 31% of patients in Group II (p less than 0.00009). The left ventricular ejection fraction was significantly lower in Group I (45.9% vs 54.5%, p less than 0.0002). The incidence of anterior infarcts was 58% in Group I and 37% in Group II (p = 0.008). These 3 factors were independent and correlated with the presence of delayed potentials. The multivariate analysis showed that the major factor was coronary occlusion with presence of delayed potentials multiplied by 6.3, whereas anterior infarction multiplied the risk of delayed potentials by 2.6 and each 10% decrease in LV ejection fraction increased the risk by 1.4.

Muscle bioenergetic impairment in hyperthyroid man: a study by 31P NMR spectroscopy

Phosphorus nuclear magnetic resonance spectroscopy was used to investigate muscle bioenergetics in 9 hyperthyroid patients who were compared with 9 normal subjects. Using the thenar muscle group as reference, the inorganic phosphate, phosphocreatine and intracellular pH were calculated at rest, during aerobic exercise (0.13 w) and post-exercise recovery. No difference was found at rest. After 5 min of exercise, the hyperthyroid patients exhibited a more important phosphocreatine depletion (41.2 +/- 8.2 vs 31.1% +/- 6.5, p less than 0.02) and a larger pH fall (6.65 +/- 0.04 vs 7.01 +/- 0.10, p less than 0.001) than the control subjects. The phosphocreatine recovery rate was not significantly different in hyperthyroid patients and control subjects. These results suggest that exercise requires more ATP in hyperthyroid patients than in normal subjects and that there is excessive dependence on glycolytic metabolism for ATP synthesis in hyperthyroidism. Phosphocreatine resynthesis, reflecting the oxidative metabolism, is not increased. These metabolic disturbances could also supply a partial explanation to the frequent exercise intolerance in hyperthyroid patients.

[Effects of fibrinolysis on late potentials in myocardial infarction]

Late potentials are an index of gravity following myocardial infarction, but there has been little investigation of the effects of fibrinolysis on their incidence. Eighty-two consecutive patients (68 men, 14 women, group men age = 55 +/- 8 years) admitted presenting with a primary infarction and who had received fibrinolytic treatment within the first four hours. Each patient was screened for late potentials, and underwent a coronary artery angiograph and determination of the left ventricular ejaculation fraction (LCEF) following the infarction. The incidence of late potentials was 38% in the patients with an occluded coronary artery (9/24) vs 12% in patients with a permeable artery (7/58) (p less than 0.02). The change in LVEF was greater if reperfusion was not achieved (47 +/- 13% vs 54 +/- 12%, p less than 0.05). This study suggests that following fibrinolysis, the incidence of late potentials is correlated with both an absence of coronary reperfusion and deterioration of left ventricular function.

Improved subtraction technique in intravenous digital left ventriculography: comparison with radionuclide studies

Adequate processing of left ventricular angiograms depends on the visualisation of all segments of the ventricular wall. At the same time, subtraction of different images can enhance different heart segments but commercially available methods do not allow simultaneous viewing of several images masked by different processes. Using our software, for each studied frame, a four quadrant display permits the simultaneous visualisation of a mask mode image, a diastolic-systolic difference image, an image obtained by subtraction of a frame at the same cycle time and a composite mask subtracted image. The composite mask image is obtained by weighting three images according to videodensitometric measurements by reference to previously acquired data. This method facilitates contour delineation and computation of the ejection fraction by area-length method. Correlation with radionuclide estimates of left ventricular ejection fraction is higher (n = 60, r = 0.90, SEE = 8%) than using the classical mask mode display (n = 60, r = 0.82, SEE = 11%). In a subgroup of 30 patients the contrast medium was injected in an antecubital vein and the correlation coefficient remained satisfactory (n = 30, r = 0.89, SEE = 7%) when compared with the classical subtraction technique (n = 30, r = 0.70, SEE = 12%). We therefore conclude that the composite mask method gives comparatively similar values for left ventricular ejection fraction to those acquired by radionuclide angiography.

[Phosphorus NMR spectroscopy. Its value in the diagnosis of metabolic myopathies. A case of Mac Ardle's disease]

Phosphorus nuclear magnetic resonance spectroscopy is a non-invasive method used to study muscle bioenergetics in vivo. A new case of Mc Ardle's disease (myophosphorylase deficiency) is reported here. In a context of metabolic myopathy this method can provide a diagnosis of glycogenosis. The spectra obtained at exercise and during recovery determine the degree of enzyme deficiency with satisfactory precision.

Skeletal muscle metabolism in the leg during exercise in patients with congestive heart failure

1. Using 31P nuclear magnetic resonance, it has previously been demonstrated that patients with congestive heart failure exhibit a greater than normal phosphocreatine (PCr) depletion in the working skeletal muscles of the arm. We have studied the importance of the work necessary to reach a similar PCr depletion ([PCr]/([PCr] + [Pi]) = 0.5) in calf muscle. Our results show significantly lower values for patients with congestive heart failure in both aerobic and ischaemic conditions (respectively: 0.009 +/- 0.007 vs 0.026 +/- 0.013 W/kg body weight, P less than 0.01; 0.29 +/- 0.16 vs 0.90 +/- 0.25 J/kg body weight, P less than 0.01). 2. This original model of skeletal muscle exercise facilitates a comparison of PCr recovery rate due to a similarity in the PCr depletion and intracellular pH in the two series at the start of recovery. However, the PCr recovery rate is similar after both normoxic and ischaemic exercise, i.e. respective percentages of PCr increase in the first 25 s recovery spectrum were: (a) aerobic exercise, congestive heart failure 133 +/- 18%, control series 138 +/- 18%; (b) ischaemic exercise, congestive heart failure 114 +/- 13%, control series 118 +/- 12%. The absence of a difference in PCr recovery rate and the greater PCr depletion by ischaemic work in patients with congestive heart failure suggest modifications that cannot be explained by a reduced blood flow to the muscle. 3. When comparing the two series, intracellular pH evolved similarly in normoxia and ischaemia during both work and recovery. Thus, no increase in anaerobic glycolytic activity appears when equivalent PCr depletion has occurred.

Effects of iron-binding proteins on in vitro uptake of 67Ga-citrate by tumor cells

A comparative study of carrier-free 67Ga-citrate uptake by Ehrlich ascites tumor cells in the presence of lactoferrin, transferrin and ferritin has demonstrated that lactoferrin considerably increases the uptake of 67Ga, and that this increase seems to be determined by its iron-load. The other iron-binding proteins assayed have a null or negative effect. Their behavior in the presence of sodium citrate supports the concept of lactoferrin-binding by the cells as responsible for the uptake. The different behavior of 67Ga-citrate iron-binding protein complexes appears to support this hypothesis.

Iron-binding proteins and 67Ga accumulation by tumor cells

Tumor cells incubated with 67Ga-citrate plus lactoferrin showed a lactoferrin concentration-dependent increase of 67Ga uptake while for transferrin the effect was an inhibition. A correlation was observed between the binding of 131I-labelled lactoferrin or 131I-labelled transferrin and the uptake of 67Ga by the cells. Saturation with iron did not change significantly the effects of the iron-binding proteins. Preincubation with lactoferrin, transferrin or ferric citrate increased 67Ga uptake. The formation of a ternary complex in which 67Ga mimics iron is discussed.

[Tamponade disclosed by functional right-left shunt reversible after surgical drainage]

The authors report a case of tamponade revealed by the discovery, during emergency radioisotope scanning of the lung, of an acquired right-to-left shunt which was reversed by surgical drainage. The patient was a 60-year old woman treated by anticoagulants for suspected pulmonary embolism who had sudden worsening of her symptoms on the 7th day of the disease.

[Value of digital subtraction of left ventriculographies by the venous route. Comparison with balanced scintigraphy of the heart cavities]

The development of numerisation material in radiology currently permits to perform usual cardiovascular tests. The authors report a series of 48 patients who benefited from the determination by numerised left ventriculography, of their stroke volume (SV). In 37 cases, the peripheral venous route is used while in 11 cases the central venous route is used, in the pulmonary artery trunk. The SV values obtained with both methods (one advocated by the manufacture and another one developed by the authors), are correlated with the SV values obtained with the isotopic method, used as reference. The correlations are satisfactory, approximately 0.79 for all patients of the study, and markedly improve when the injection of the contrast material is performed in the pulmonary artery (approximately 0.95). The authors conclude that determination of the left ventricle SV by numerisation is an interesting technique in centers where there is no department of nuclear medicine, and is absolutely necessary to complement right catheterisation.

Iron-Binding Proteins and 67Ga Accumulation by Tumor Cells

Tumor cells incubated with 67Ga-citrate plus lactoferrin showed a lactoferrin concentration-dependent increase of 67Ga uptake while for transferrin the effect was an inhibition. A correlation was observed between the binding of 131l-labelled lactoferrin or 131l-labelled transferrin and the uptake of 67Ga by the cells. Saturation with iron did not change significantly the effects of the ironbinding proteins. Preincubation with lactoferrin, transferrin or ferric citrate increased 67Ga uptake. The formation of a ternary complex in which 67Ga mimics iron is discussed.

On the role of transferrin in 67Ga uptake by tumor cells

In vitro uptake of 67Ga-citrate and 59Fe-citrate by DS sarcoma cells in the presence of tumor-bearing animal blood plasma showed a dramatic inhibition of both 67Ga and 59Fe uptakes: about 1/10 of 67Ga and 1/50 of the 59Fe are taken up by the cells. Subcellular fractionation appears to indicate no specific binding to cell structures, and the difference of binding seems to be related to the transferrin chelation and transmembrane transport differences.

Mechanisms of gallium-67 accumulation by tumors: role of cell membrane permeability

The effects of citrate ion on in vitro and in vivo uptake of [67Ga]citrate by tumor cells have been studied. Carrier-free [67Ga]citrate seems to follow the physical diffusion of citrate ions into the cell, and the presence of carrier gallium inhibits that diffusion, reducing considerably its uptake. These results appear to support the hypothesis that increased permeability of tumor cells is the principal cause of [67Ga]citrate accumulation by tumors.

Sustained improvement in myocardial perfusion four to six years after PTCA in patients with a satisfactory angiographic result, six months after the procedure

Of 46 consecutive patients who underwent percutaneous transluminal coronary angioplasty (PTCA) from April 1980 to August 1982 and who had a satisfactory angiographic result six months later, one died of cancer and 41 had a detailed evaluation with exercise single-photon emission computed tomography (SPECT, 40 patients) or repeat coronary angiography (one patient), 48-78 months after the procedure. During follow-up, two patients had recurrent angina due to progression of coronary artery disease requiring a second PTCA procedure of another coronary artery; one of them later had a limited myocardial infarction in an area supplied by the vessel initially dilated. At follow-up, only one patient had definite angina. All but one patient had a negative exercise test. Myocardial perfusion during exercise in the PTCA-related area, assessed by SPECT, was normal in 90% of the patients and showed a limited defect due to reversible ischaemia in the remaining four (10%). It is concluded that patients with a less than 50% stenosis six months after PTCA show sustained improvement in their functional status and myocardial perfusion, four to six years after the procedure suggesting continued patency of the coronary artery.

Haemorheological abnormalities in arterial hypertension and their relation to cardiac hypertrophy

Haemorheological characteristics were measured in a group of 52 patients with essential arterial hypertension (HT), and were compared with those of a group of normotensive subjects. The relationships between the arterial blood pressure (BP), the echocardiographic indices of left ventricular hypertrophy (LVH), and the haemorheological measurements, were studied. The group of hypertensive patients was found to have a hyperviscosity syndrome with significant elevations of blood viscosity at all shear rates (for gamma = 0.20/s, 29.6 +/- 0.6 versus 28.0 +/- 0.3 mPa.s, P less than 0.01: for gamma = 128/s, 4.2 +/- 0.05 versus 4.1 +/- 0.02 mPa.s, P less than 0.02, of plasma viscosity (1.29 +/- 0.01 versus 1.22 +/- 0.06 cSt, P less than 0.001); of erythrocyte aggregation index (17.8 +/- 0.06 versus 14.6 +/- 0.4, P less than 0.001); of erythrocyte filterability index (13.3 +/- 0.5 versus 8.8 +/- 0.2, P less than 0.001) and plasma fibrinogen level (3.4 +/- 0.9 versus 2.8 +/- 0.6 g/l, P less than 0.02). The haematocrit did not differ from that of normotensive subjects (43.3 +/- 0.6 versus 44.7 +/- 0.5%, NS). The left ventricular mass was increased and was positively correlated with the blood viscosity at a high shear rate (r = 0.38, P less than 0.01) and with the erythrocyte aggregation index (r = 0.47, P less than 0.01). Systolic, diastolic, and mean arterial blood pressures were positively correlated with the left ventricular mass (r = 0.34-0.47, P less than 0.05) and with the erythrocyte aggregation index (r = 0.42-0.46, P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

On the Role of Transferrin in 67Ga Uptake by Tumor Cells

In vitro uptake of 67Ga-citrate and 59Fe-citrate by DS sarcoma cells in the presence of tumor-bearing animal blood plasma showed a dramatic inhibition of both 67Ga and 59Fe uptakes: about ii/io of 67Ga and 1/5o of the 59Fe are taken up by the cells. Subcellular fractionation appears to indicate no specific binding to cell structures, and the difference of binding seems to be related to the transferrin chelation and transmembrane transport differences

[Semiquantitative evaluation of mitral insufficiency by pulsed Doppler technic. Value of a simple index of left auricular cartography (apropos of a series of 63 patients)]

The authors advocate a semiquantitative evaluation of mitral regurgitation (MR), based on the extent of the left intra-atrial systolic jet. Their study was performed in a series of 63 consecutive patients explored by: (1) catheterization with left ventriculography on two planes for either ischaemic heart disease (24 cases) or cardiac valve disease (39 cases including 2 with mitral valve prosthesis), and (2) pulsed Doppler ultrasound combined with two-dimensional echocardiography for evaluation of MR carried out 24 or 48 hours prior to catheterization. Five grades of MR (0 to IV) were determined by ventriculography according to the time and degree of left atrial opacification. Similarly, five grades of MR (0 to IV) were determined by Doppler ultrasound, considering only the maximum distance from the mitral annulus plane. This distance was evaluated on at least 3 projections: apical for the 4 and 2 cavities, parasternal for the greater axis. The Doppler method correlated fairly well with the angiography, whether or not grade 0 was included (r = 0.87 and r = 0.72 respectively). However, some major MR may be underestimated; thus, out of 13 RM of angiographic grade III or IV, three (23 p. 100) were graded II by the Doppler technique. Conversely, some minute or moderate MR may be overestimated: out of 33 MR of angiographic grade I or II, four (12 p. 100) were graded III or IV by the Doppler technique.(ABSTRACT TRUNCATED AT 250 WORDS)

Placebo-controlled study of oral enoximone in congestive heart failure with initial and final intravenous hemodynamic evaluation

Seventeen patients with stable congestive heart failure (class II and III New York Heart Association) received intravenous and oral enoximone in a 2-part study. Hemodynamic data were first obtained after intravenous administration of 0.75 mg/kg of enoximone; data were again obtained after 12 weeks of therapy with either oral enoximone (150 mg 3 times daily) or placebo. The efficacy and safety of oral enoximone were also studied in a 12-week, double-blind randomized format. In the intravenous study, enoximone was delivered over 5 minutes and hemodynamic data were measured for up to 12 hours after. Cardiac index increased 2.76 +/- 0.63 to 3.42 +/- 0.72 liters/min/m2), pulmonary wedge pressure decreased (19.5 +/- 8.8 to 14.6 +/- 8.0 mm Hg) as did mean arterial blood pressure (101 +/- 14.8 to 85 +/- 13.7 mm Hg) and systemic vascular resistance (1,880 +/- 573 to 1,254 +/- 383 dynes s cm-5). Heart rate increased slightly (82 +/- 17 to 86 +/- 14 beats/min). All these changes were maximal 1 to 2 hours after infusion and lasted 8 hours at least. Patients were then randomized double-blind to oral treatment. Baseline values showed that the 7 patients who received placebo had more severe CHF. Therefore, comparison might be biased. Patient overall assessment showed a continuous benefit in both groups. Ejection fraction improved from 30.1 +/- 6.8% to 33.9 +/- 9.9% in the enoximone group while it remained unchanged with placebo (23.4 +/- 6.5% to 23.4 +/- 1.5%).(ABSTRACT TRUNCATED AT 250 WORDS)

[Current role of radionuclide imaging in pediatric cardiology]

Three main nuclear medicine methods are used in paediatric cardiology: sequential first-pass radionuclide imaging of the cardiac cavities, radionuclide equilibrium ventriculography and radionuclide myocardial imaging. Valuable functional information is obtained, and invasive explorations can be avoided in an ever increasing number of cases. Of particular interest is left-to-right shunt measurement which indicates that atrial septal defects must be surgically corrected when the pulmonary/systemic flows ratio (QP/QS) is above 2. This technique is also useful to evaluate the tightness of repairs in ventricular and atrial septal defects. Radionuclide studies of the right and left ventricles may detect dysfunction in one or the other cavity. The left ventricular ejection fraction is reduced in myocardiopathy an in aortic or mitral valve diseases seen at a late stage. The right ventricular function is often abnormal, notably during exercise, after repair of the tetralogy of Fallot and after atrial correction of complete transposition of the great arteries. An altered ejection fraction in patients with single ventricle is also a sign of deterioration. Right ventricular diastolic overload evaluated by radionuclide equilibrium ventriculography correlates with the QP/QS ratio value in atrial septal defects and with the inducibility of ventricular tachycardia by endocavitary pacing in repaired tetralogy of Fallot. Thallium 201 myocardial imaging provides information on myocardial ischaemia, notably that associated with congenital abnormalities of the coronary arteries. Its use had now been extended, albeit with some limitations, to the evaluation of right ventricular systolic overload. Other radionuclide techniques are being developed with new tracers: Kryton 81m for studies of the right ventricle, short-lived radionuclides for first-pass studies, Iodine 123-labelled fatty acids for myocardial imaging. More recently, some substrates, such as deoxyglucose, have been labelled with positron emitters permitting in vivo metabolic studies.

Sensitivity and specificity of radionuclide equilibrium angiocardiography for detection of hemodynamically significant secundum atrial septal defect

To determine the value of gated equilibrium angiography in secundum atrial septal defect (ASD) in children, the first pass pulmonic/systemic flow ratio (Qp/Qs) was compared with diastolic count ratio (DCR) and stroke count ratio (SCR) of the two ventricles. In 50 children we have found a correlation between Qp/Qs and DCR (r = 0.71) and between Qp/Qs and SCR (r = 0.66). For detection of significant atrial shunt (QP/Qs greater than 1.5) the sensitivity of DCR greater than 2 was 0.81 and the specificity 0.75. For SCR greater than 1.5 we sensitivity and specificity values of 0.87 and 0.71 respectively. Left and right ventricular ejection fractions were normal (0.67 +/- 0.08 and 0.50 +/- 0.07).

Experimental evidence for the probable involvement of calcium ion transport in 67Ga uptake by tumour cells

The study of 67Ga-citrate uptake and calcium transport in Ehrlich ascites tumour cells seems to indicate that their peculiar characteristic of increased permeability to extracellular calcium ion might be responsible for their 67Ga accumulation. Experiments performed under different conditions of extracellular calcium, temperature, and presence of ionophore and other plasma membrane modifying agents such as lanthanum appear to corroborate this hypothesis.

[Isotopic exercise tests and selection of cases of inferior infarction requiring coronarography]

Exercise tests involving isotopes were evaluated in 38 subjects presenting inferior myocardial necrosis. Cardiographic data were used to calculate sensitivity and specificity of the method in detection of subjects requiring surgical treatment. Sensitivity was 90% and specificity 62% when three criteria were employed: ECG of positive exertion, reversible diminished accumulation of thallium 201 outside the necrotic site or decrease in the fraction of ejection force. Examination of the fraction of ejection force improved the results of myocardial scanning using thallium and increased detection of subjects requiring surgery from 61% to 90%.

[Phase imaging of isotopic ventriculographies: contribution to the study of the Wolff-Parkinson-White syndrome]

This study compared the phase images of 12 normal subjects and 14 patients with right ventricular and 5 patients with left ventricular preexcitation. The phase images obtained from equilibrium radionuclide ventriculographies in the left anterior oblique portion with an ECG trigger: Fourier analysis was used to measure the phase and amplitude of the variations. In normal subjects the mean difference in phase was nearly zero: in 12 of the 14 patients with right ventricular preexcitation, right ventricular preceded left ventricular contraction (LV phase - RV phase = + 23 degrees); injection of Ajmaline normalised the ECG and suppressed the premature right ventricular contraction during right ventricular preexcitation (LV phase - RV phase = nearly zero), demonstrating a direct relationship between the abnormal depolarisation and abnormal contraction. In left sided Kent bundles, phase imaging did not seem to show significant premature ventricular contraction under basal conditions. Atrial pacing, which accentuated both left and right electrical preexcitation, increased the difference in ventricular phase. Finally, a satisfactory correlation was observed between the presumed locations of the accessory pathways and the zones of premature right and left ventricular contraction.