P668 Echocardiographic description of mitral annular disjunction in mitral valve prolapse and implication in arrhythmic risk stratification

Introduction

Mitral annular disjunction (MAD) is an anatomical variation of the mitral annulus, characterized by an atrial displacement of the leaflet’s hinge points. It is associated with severe ventricular arrhythmias (VA) in mitral valve prolapse (MVP).

Purpose

The aim of this study was to assess MAD in MVP by echocardiography, analyze the reproducibility of measurements and evaluate its importance for arrhythmic risk stratification along with strain analysis of myocardial deformation.

Methods

Two hundred and sixty patients with MVP were included. MAD was evaluated and measured by two observers in the parasternal long axis and in the apical views. Myocardial longitudinal strain was analyzed by speckle-tracking.

Results

Ninety four patients (36.2%) of MVP patients presented MAD. These patients were younger (53.7 ± 15.1 vs 58.4 ± 17.6, p = 0.033) with higher rate of atypical chest pain (21.3% vs 11.5%, p = 0,041) and bileaflet prolapse (50.5% vs 32.3%, p = 0.004). Para-sternal long-axis view was the incidence of choice to detect MAD with a moderate inter-observer concordance (Kappa of 0.55), good correlation (r = 0.69, p < 0.01) and inter-class correlation coefficient (0.82; 0.67 – 0.90). Twenty patients (7.7%) had a history of severe VA. Among them, no difference was noted in terms of presence (35% vs 36.3%, p = 0.911) or length of MAD (11.1 ± 2.5 vs 11.2 ± 3.1, p = 0.937). However, deformation analysis showed reduced global longitudinal strain (18.6 ± 3.1 vs 21.3 ± 3.3%, p = 0.001) and higher mechanical dispersion values (46 ± 13 vs 37.4 ± 12.9 ms, p = 0.002)in comparison to the rest of the MVP population.

Conclusion

No significant association was found between severe VA and the presence or severity of MAD in MVP patients. Increased mechanical dispersion and reduced global longitudinal strain may be helpful for arrhythmic risk stratification.

Abstract P668 Figure. Comparison of MD and GLS

[Evaluation of cardiac MRI in the follow up assessment of patients with pulmonary arterial hypertension]

Haemodynamic follow up in pulmonary arterial hypertension (PAH) is currently based on right heart catheterisation (RHC). The primary objective of the EVITA study is to compare the use of cardiac magnetic resonance imaging (cMRI) with RHC in the identification of an unfavourable hemodynamic status. The secondary objectives are to determine the role of cMRI in the follow up process. Patients will undergo at diagnosis and at follow up visits both RHC and cMRI. Patients will be followed and treated according to the current guidelines. The primary endpoint will be an unfavourable haemodynamic status defined by cardiac index<2.5L/min/m² or a right atrial pressure≥8mm Hg measured with RHC compared with a cardiac index<2.5L/min/m² or right ventricle ejection fraction<35% or an absolute decrease of 10% from the previous measurement with cMRI. Exact values of sensitivity, specificity and 95% confidence intervals will be computed. A population of 180 subjects will have a power of 90% with an α risk of 5%. Univariate and multivariate Cox analysis will allow answering to the secondary objectives. We expect to demonstrate that cMRI could be partly used instead of RHC in the follow up of patients with PAH.

Influence of Thoracic Aortic Inflammation and Calcifications on Arterial Stiffness and Cardiac Function in Older Subjects

BACKGROUND

Vascular aging is accompanied by gradual remodeling affecting both arterial and cardiac structure and mechanical properties. Hypertension is suggested to exert pro-inflammatory actions enhancing arterial stiffness.

OBJECTIVE

To determine the influence of thoracic aortic inflammation and calcifications on arterial stiffness and cardiac function in hypertensive and normotensive older subjects.

DESIGN

A prospective study.

SETTING

An acute geriatrics ward of the University Hospital of Nancy in France.

SUBJECTS

Thirty individuals ≥ 65 years were examined, including 15 hypertensive subjects and 15 controls well-matched for age and sex.

MEASUREMENTS

Applanation tonometry was used to measure aortic pulse wave velocity (AoPWV) and carotid/brachial pulse pressure amplification (PPA). Left ventricular parameters were measured with magnetic resonance imaging. Local thoracic aortic inflammation and calcification were measured by 18 F-fluorodeoxyglucose positron emission tomography/computed tomography imaging. Biomarkers of low-grade inflammation were also quantified.

RESULTS

AoPWV was higher in elderly hypertensive subjects comparatively to normotensive controls (15.5±5.3 vs. 11.9±2.5, p=0.046), and hypertensives had a higher calcification volume. In the overall population, calcifications of the thoracic descending aorta and inflammation of the ascending aorta accounted for respectively 18.1% (p=0.01) and 9.6% (p=0.07) of AoPWV variation. Individuals with high levels of calcifications and/or inflammation had higher AoPWV (p=0.003). Inflammation had a negative effect on PPA explaining 13.8% of its variation (p<0.05).

CONCLUSION

This study highlights the importance of local ascending aortic inflammation as a potential major actor in the determination of PPA while calcifications and hypertension are more linked to AoPWV. Assessment of PPA in the very elderly could provide complementary information to improve diagnostic and therapeutic strategies targeting ascending aortic inflammation.

Analysis of the relationship between interictal electrical source imaging and PET hypometabolism

The aim of this paper is to compare interictal EEG source localizations with statistical analysis of hypometabolisms in PET brain imaging. Both methods are currently used in the pre-surgical evaluation of drug-resistant partial epilepsy, but the relationship between electrical source localizations and hypometabolic areas has not been well defined yet. At the present time, these two methods have been performed on five patients in order to develop a comparative quantitative study with these first results which should be then extended to a larger patient database.

[Association of Wolff-Parkinson-White syndrome with isolated non-compaction of the left ventricle: a case report]

The Wolff-Parkinson-White syndrome (WPW) may be associated with a number of cardiac pathologies, especially congenital disease, in 7.5 to 17% of cases. The authors report a rare association of the WPW syndrome with two Kent bundles, right and left septal, with non-compaction of the left ventricle in a 52 year old man. This was a chance finding during systematic echocardiography after ablation, and confirmed by cardiac MRI. The patient was asymptomatic.

EANM/ESC procedural guidelines for myocardial perfusion imaging in nuclear cardiology

The European procedural guidelines for radionuclide imaging of myocardial perfusion and viability are presented in 13 sections covering patient information, radiopharmaceuticals, injected activities and dosimetry, stress tests, imaging protocols and acquisition, quality control and reconstruction methods, gated studies and attenuation-scatter compensation, data analysis, reports and image display, and positron emission tomography. If the specific recommendations given could not be based on evidence from original, scientific studies, we tried to express this state-of-art. The guidelines are designed to assist in the practice of performing, interpreting and reporting myocardial perfusion SPET. The guidelines do not discuss clinical indications, benefits or drawbacks of radionuclide myocardial imaging compared to non-nuclear techniques, nor do they cover cost benefit or cost effectiveness.

[The best of nuclear cardiology and MRI in 2002]

In Nuclear Cardiology, the year 2002 was marked by a great number of studies on the gated-SPECT, which allows joint analysis of left ventricle perfusion and contraction. Even if conventional perfusion tomoscintigraphy confirms its foreground role, notably for prognostic evaluation, the value of the gated-SPECT is particularly significant in all areas of its use: coronary heart disease screening, prognosis evaluation, and myocardial viability assessment. Cavitary tomoscintigraphy allows direct evaluation of the ejection fraction and volumes in both ventricles. This innovative technique has been the subject of a great deal of methodological validation work, and will very likely replace traditional isotopic angiography in the future. At last, the value of MIBG scintigraphy for prognostic evaluation, of cardiac insufficiency has been defined, as has its significance for providing evidence of the effect of betablockers on pre-synaptic sympathetic innervation. The year 2002 has also been very fertile for technological innovations, methodological work, and in clinical studies concerning cardiac MRI. In particular, the significance of MRI for evaluating myocardial viability and the transmural extension of necrosis is now well established. Similarly, MRI is becoming an inescapable element in the assessment of congenital cardiopathy. However, its diffusion on a wider scale will only be possible if there is direct collaboration between cardiologists and radiologists.

Effect of exercise on lung-perfusion scanning in patients with bronchogenic carcinoma

The aim of this study was to determine whether perfusion-scintillation scanning, used as a predictive pre-operative index of lung functionality in patients with lung cancer, is affected by the level of pulmonary blood flow (PBF). Twenty patients with primary lung cancer underwent spirometry and a radionuclide-perfusion scan (macroaggregated albumin particles labelled with 99mTechnetium) both at rest and during the last minute of a ramp-like increase in work rate until exhaustion. On average, the perfusion of the lung with the tumour was significantly reduced by the same magnitude at rest and during exercise (mean+/-SD: -9+/-6% versus -10+/-4% of the cardiac output), regardless of the extent of the tumour. However, subject-by-subject analysis revealed that in two patients, a larger decrease in the perfusion of the lung with the tumour was observed during exercise than at rest (-11% and -17%, respectively). This leads to an underestimation of predictive postoperative functional parameters if resting values are used in these patients. The use of perfusion scintigraphy at rest therefore gives a clear picture of the functionality of the lung before resection in most patients requiring surgery.

[The best of 2001. Nuclear cardiology and MRI]

The year 2001 has been very fertile for innovations and developments in the field of cardiac imaging. In Nuclear Cardiology, this year has been marked above all by a very large number of studies on the gated-SPECT, which allows joint analysis of the perfusion and contraction of the left ventricle. The contribution of this technique is recognised as being very significant in all fields using conventional tomoscintigraphy (screening for cardiac disease, evaluations of prognosis and viability,...). Innovation has also been focused in the field of radio-tracers, with studies on the very promising markers of apoptosis or cellular hypoxia. Lastly, much work has been conducted on the gamma-camera, especially to adapt it for imaging with the tracers used in positron emission tomography (PET). This will enable the distribution to all the Nuclear Medicine services of FDG imaging, which is the reference technique for studying myocardial viability. In MRI much work has been carried out on sequences using gadolinium, a vascular contrast agent, in order to identify and localise the sequelae of infarction, even when they are limited to the sub-endocardium. The most spectacular technical innovations were probably in the methods allowing an increase of the recorded signal (SENSE) and in updating the imaging sequences in real time, without apnoea and without ECG synchronisation. But, as every year, significant progress has also been made in MRI angiography of the coronary vessels, and thus in the analysis of myocardial tissue perfusion, with sequences which can be used without the injection of contrast medium.

Measurement of blood volume after haemodilution with haemoglobin-based oxygen carriers by a radiolabelled-albumin method

Recent studies have shown that the use of haemoglobin-based oxygen-carrying solutions (HBOCs) for perioperative haemodilution could significantly reduce the need for packed red blood cells in clinical practice. Though the effects of HBOCs on plasma volume have been characterized in experimental models of volume resuscitation from hypovolaemic shock, little is known about their action in normovolaemic haemodilution conditions. We therefore applied a radiolabelled serumalbumin method to determine blood volume after haemodilution with crosslinked or conjugated haemoglobin, in comparison with a reference solution of hydroxyethyl starch (HES). Three groups of New Zealand white rabbits were studied (n = 7 each group) subjected to moderate exchange transfusion with low molecular weight HES, bis(3,5-dibromosalicyl)fumarate crosslinked haemoglobin (alphaalpha-Hb), or dextran-conjugated haemoglobin (Hb-Dex-BTC). HES induced no changes in heart rate and blood pressure. The amplitude and duration of blood pressure increase and bradycardia were similar in both haemoglobin groups. A significant contraction of blood volume (12%) was observed 60 min after haemodilution with alphaalpha-Hb, compared to HES and Hb-Dex-BTC. At the same time point, a decrease in absolute haemoglobin (plasma haemoglobin x plasma volume) was also noted. This study suggests that in haemodilution conditions, the specific oncotic properties and circulating persistence of crosslinked and conjugated haemoglobin solutions affect the pattern of blood volume distribution differently.

Detection and prediction of acute heart transplant rejection with the myocardial T2 determination provided by a black-blood magnetic resonance imaging sequence

OBJECTIVES

This study aimed to determine whether the myocardial T2 relaxation time, determined using a black-blood magnetic resonance imaging (MRI) sequence, could predict acute heart transplant rejection.

BACKGROUND

The use of black-blood MRI sequences allows suppression of the confusing influence of blood signal when myocardial T2 is calculated to detect myocardial edema.

METHODS

A total of 123 investigations, including cardiac MRI and myocardial biopsy, were performed 8 +/- 11 months after heart transplantation. Myocardial T2 was determined using an original inversion-recovery/spin-echo sequence.

RESULTS

A higher than normal T2 (> or = 56 ms) allowed an accurate detection of the moderate acute rejections evidenced at baseline biopsy (> or = International Society for Heart and Lung Transplantation grade 2): sensitivity, 89% and specificity, 70% (p < 0.0001). T2 was increased in grade 2 (n = 11) compared with grade 0 (n = 49, p < 0.05), grade 1A (n = 34, p < 0.05) and grade 1B (n = 21, p < 0.05); T2 was further increased in grade 3 (n = 8) compared with grade 2 (p < 0.05). In addition, in patients without rejection equal to or greater than grade 2 at baseline, a T2 higher than normal (> or = 56 ms) was correlated with the subsequent occurrence of equal or greater than grade 2 rejection within the next three months: sensitivity 63% (12/19) and specificity 78% (64/82) (p = 0.001).

CONCLUSIONS

Myocardial T2 determined using a black-blood MRI sequence, is sufficiently sensitive to identify most of the moderate acute rejections documented with biopsy at the same time, but is also a predictor of the subsequent occurrence of such biopsy-defined rejections.

A comparison of the overall first-pass kinetics of thallium-201 and technetium-99m MIBI in normoxic and low-flow ischaemic myocardium

The specific impact of ischaemia on the myocardial kinetics of thallium-201 and technetium-99m 2-methoxy-2-isobutylisonitrile (MIBI) remains a matter of debate. Using an isolated heart model perfused with red blood cell-enhanced perfusate, we compared the overall first-pass kinetics of 201Tl and MIBI under haemodynamically stable conditions of low-flow ischaemia (> 50% reduction in normal coronary flow and a > or = 20 mmHg fall in systolic contraction pressure, n = 10) and normoxia (n = 11). For both 201Tl and MIBI, we found that under ischaemic conditions (as compared with normoxia) there was a higher initial net extraction fraction (201Tl: 0.78 +/- 0.03 vs 0.72 +/- 0.06, P = 0.006; MIBI: 0.49 +/- 0.10 vs 0.39 +/- 0.11, P = 0.03), a lower clearance rate in the 30 min following extraction (% decrease in cardiac uptake: 201Tl: 30 +/- 12 vs 47 +/- 14, P = 0.02; MIBI: 5 +/- 5 vs 13 +/- 11, P = 0.02) and a higher retention fraction at 30 min (20lTl: 0.54 +/- 0.10 vs 0.39 +/- 0.12, P = 0.004; MIBI: 0.46 +/- 0.08 vs 0.33 +/- 0.12, P = 0.01). Multivariate analyses, however, revealed that all myocardial kinetic parameters of both tracers were dependent only on coronary flow rates, without any additional significant impact of the presence of ischaemia or states of contractility or oxidative metabolism. We conclude that the myocardial fractional retention of both 201Tl and MIBI is strongly correlated with the decrease in coronary flow during ischaemia. This inverse relationship with coronary flow derives from both the flow-dependent increase in the initial myocardial extraction and the decrease in the subsequent myocardial washout of the tracers.

Dipyridamole and exercise SPET provide different estimates of myocardial ischaemic areas: role of the severity of coronary stenoses and of the increase in heart rate during exercise

In patients unable to perform a maximal exercise test, dipyridamole single-photon emission tomography (SPET) has a higher capacity than exercise SPET to detect coronary artery disease (CAD). However, in patients with myocardial ischaemia who are able to perform a maximal exercise test, it is not known whether these two tests may be equally used to assess the areas of myocardial ischaemia. This study was aimed at comparing the results provided by dipyridamole and exercise SPET in CAD patients with documented exercise myocardial ischaemia. Forty CAD patients who had undergone exercise thallium-201 SPET and who had myocardial ischaemia documented by an unequivocally positive exercise test underwent an additional 201Tl SPET study after dipyridamole infusion and low-level (40 W) exercise. The extent of defects was compared between the two tests and predictors of discrepant results were sought among data from exercise testing and coronary angiography. The extent of SPET defects was equivalent between the two tests in only 11 patients (28%), larger defects being observed with exercise in 18 [average difference: 12%+/-5% of left ventricle (LV)] and with dipyridamole in 11 (average difference: 15%+/-11% of LV). The best independent predictors of discrepancies between the two tests were: (1) increase in heart rate at exercise SPET, with defects being smaller at exercise than after dipyridamole in none of the patients with an increase >60 bpm (0/14), but in 42% of the others (11/26; P=0.004); and (2) an ischaemic territory related to a <70% coronary stenosis, for which SPET defects were always induced at exercise (10/10) but in only 30% (3/10) with dipyridamole (P=0.0004). Exercise and dipyridamole SPET provide different estimates of myocardial ischaemic areas. Dipyridamole allows the unmasking of perfusion abnormalities in patients who have low increases in heart rate at exercise SPET. However, dipyridamole is also much less efficient at inducing perfusion abnormalities in the ischaemic areas supplied by coronary stenoses of intermediate severity at rest angiography.

[Evaluation of prognosis after Q wave myocardial infarction. Comparison of invasive and noninvasive diagnostic strategies]

The predictive value of several diagnostic strategies after myocardial infarction was assessed in 178 patients (mean age 55 +/- 9 years) treated medically after a primary Q wave myocardial infarction. Within 6 weeks of onset of symptoms the authors performed exercise stress test coupled with Thallium 201 scintigraphy, isotopic left ventriculography and conventional coronary angiography with ventriculography. The average left ventricular ejection fraction was 45 +/- 12%. Two non-invasive diagnostic strategies with and without results of scintigraphy and two invasive strategies with and without ventricular volumes were studied. The average follow-up period was 58 +/- 22 months. Sixteen cardiac deaths occurred. Multivariate Cox analysis showed that, in contrast to left ventricular volumes, coronary angiography did not provide additional prognostic value compared with the non-invasive model with Thallium scintigraphy and did not appear to be essential in terms of predictive value in this population. Moreover, the size of reversible defect on Thallium scintigraphy was an independent predictive factor of cardiac death and provided additional and independent prognostic information in the non-invasive and invasive strategies. Therefore, the reduction of residual ischaemia by coronary revascularisation could improve the long-term prognosis after myocardial infarction.

Effects of medical therapy on outcome assessment using exercise thallium-201 single photon emission computed tomography imaging: evidence of a protective effect of beta-blocking antianginal medications

OBJECTIVES

The purpose of this study was to determine whether antianginal medications modify the prognostic significance of exercise single photon emission computed tomography (SPECT) ischemia.

BACKGROUND

Antianginal medications (especially beta-adrenergic blocking agents) limit exercise SPECT ischemia, but it is not known whether such medications also modify the prognostic effect of exercise SPECT ischemia.

METHODS

We included 352 patients with coronary heart disease, who had exercise Tl-201 SPECT and coronary angiography, and who were initially treated medically. Survival Cox models were applied in patients for whom classes of antianginal medications taken at exercise SPECT were the same as those prescribed for follow-up (GI; n = 136), and in patients for whom new classes of antianginal medications, including beta-blockers (GII; n = 79) or not including beta-blockers (GIII; n = 113), were added for follow-up.

RESULTS

During a mean 5.3+/-1.6 years of follow-up, 45 patients had cardiac death or myocardial infarction. Variables reflecting necrosis (irreversible defect extent, left ventricular ejection fraction) and those from coronary angiography provided equivalent prognostic information in the three groups. In contrast, the SPECT variable reflecting ischemia (reversible defect extent), which provided comparable prognostic information in GI (p = 0.005) and GIII (p = 0.004), lost its prognostic significance (p = 0.54) in GII, and was associated with a lower relative risk in GII than in GI or GIII (both p < 0.05).

CONCLUSIONS

In patients with coronary heart disease, the introduction of antianginal medications, when including beta-blockers, appears to have a favorable effect on the deleterious prognostic effect of exercise ischemia.

The kinetics of beta-methyl-substituted labelled fatty acids in ischaemic myocardium: an analysis in man and with a blood-perfused isolated heart model

beta-Methyl-substituted free fatty acids (FFAs) have been developed for myocardial single-photon emission tomography (SPET) imaging, but little is known about their kinetics in ischaemic conditions. The aim of this study was to determine the changes in the myocardial kinetics of a beta-methyl-branched FFA, [123I]16-iodo-3-methyl-hexadecanoic acid (MIHA), under ischaemic conditions. The kinetics of MIHA were analysed: (a) using a blood-perfused isolated heart model subjected to moderate ischaemia (50% flow reduction) and (b) in patients who had an exercise thallium-201 SPET defect corresponding to either necrotic (n = 13) or chronically ischaemic and viable (n = 15) myocardium, and who underwent two consecutive SPET studies after MIHA injection. In animals, the myocardial early retention fraction of MIHA, but not its clearance rate, was dependent on coronary flow, the early retention fraction being higher in ischaemic than in normoxic conditions (0.24 +/- 0.10 vs 0.14 +/- 0.04, P = 0.004). In the patient SPET studies, the uptake of MIHA calculated in ischaemic and viable areas (G1: 74% +/- 9% of maximal left ventricular value) was different from that calculated in necrotic (G2: 59% +/- 7%, P < 0.001) or normal (G3: 88 +/- 6%, P < 0.001) areas. By contrast, MIHA-clearance calculated between the two consecutive SPET studies was not different in G1, G2 and G3. Unlike in the case of other FFAs, the myocardial clearance of MIHA is not decreased by ischaemia. However, the early retention of MIHA is increased in the case of a moderate reduction in coronary flow, a property which might help in the detection of viability in chronically ischaemic myocardium.

Induction of sustained ventricular tachycardia after surgical repair of tetralogy of Fallot

Between 1980 and 1996, 89 unselected consecutive patients with repaired tetralogy of Fallot (TOF) underwent examination, including a prospective right ventricular programmed stimulation with the same protocol (S1 S2, S3, S4). Age at surgery was 4.2 +/- 3.5 years and age at electrophysiologic study was 10.9 +/- 6.5 years. Follow-up since surgery was 14.4 +/- 4.8 years and patient follow-up after programmed stimulation was 7.8 +/- 4.2 years. The aim of this study was to evaluate the main predictors of the inducibility of a sustained monomorphic ventricular tachycardia (VT) and its significance to identify a group of patients at risk of sudden death: 21 (group A) had and 68 (group B) had no induced sustained VT. The induction of VT was related to older age at programmed stimulation, prolonged QRS duration, presence of complex ventricular arrhythmia, symptoms, right ventricular overload, and increased right ventricular systolic pressure. Predictors of induced VT selected by multivariate analysis were age at electrophysiologic study (p <0.0001), previous palliative shunts (p <0.001), right ventricular systolic pressure (p <0.007), and symptoms (p <0.005). Among group A patients, 4 had previous sustained VT before stimulation, and 1 had sustained VT only during follow-up after stimulation. No patients of group B had clinical sustained VT. Late mortality was low but similar between both groups. A negative electrophysiologic study may be helpful for the management of patients after surgical repair of TOF, but because the arrhythmic event rate is low, the findings of even a positive electrophysiologic study should be interpreted with caution.

[Isotopes and idiopathic dilated cardiomyopathy]

Idiopathic dilated cardiomyopathy is a myocardial disease of unknown cause which carries a poor prognosis. Different isotopic techniques provide information about the factors which influence its development and about its severity and potential to progress. The results of isotopic right and left ventriculography are important in establishing the prognosis. Thallium 201 myocardial scintigraphy can show myocardial perfusion defects which are often multiple and widespread. The prognostic significance of these abnormalities has not been fully established. Gallium-67 myocardial scintigraphy may show inflammatory phenomena within the myocardium, orientating the diagnosis to myocarditis. MIBG scintigraphy assesses adrenergic presynaptic activity which, when decreased (heart/mediastinum uptake < 1.2), carries a very poor prognosis. Finally, anti-myosin antibody myocardial scintigraphy may show regions of acute or subacute cellular destruction which may be markers of myocardial toxicity of alcohol and have important prognostic implications in the medium term.

[5-year results of arterial correction in transposition of great vessels]

A prospective study was performed on in-hospital patients between June 1985 and July 1992 to assess the 5 year results of surgical detransposition of the great arteries. Clinical examination, electrocardiography, echocardiography, right and left heart catheterisation with selective coronary angiography, isotopic right and left ventricular ejection fractions at rest and with infusion of dobutamine and SestaMibi myocardial perfusion scintigraphy at rest and with dipyridamole, were performed during the 5th year after surgery. Twenty-six children underwent this protocol: eight others did not come for examination because they had moved from the region, one of whom had suffered regressive postoperative myocardial infarction. All patients were asymptomatic and had only minor electrocardiographic changes. Stenosis of the pulmonary tract was observed in 38.5% but only one case of stenosis at the origin of the right pulmonary artery required percutaneous angioplasty, which was successful. Pulmonary regurgitation was a common echocardiographic finding (65.4% of cases) but rarely severe (1/26: 3.9%). Aortic regurgitation was also observed commonly (53.8%), nearly always mild, grade I (13/14 cases). No significant stenosis of the aortic anastomosis was observed. The right and left ventricular ejection fractions were normal at rest except in one case and all values improved with dobutamine. Myocardial scintigraphy did not show any perfusion defect and there was no stenosis or occlusion of the coronary arteries at coronary angiography. The authors conclude that the results of arterial detransposition at 5 years are satisfactory in this series, with no cases of major obstructive lesions, major ventriculo-arterial regurgitation, ventricular dysfunction or coronary lesions. However, longer term trials with larger numbers of patients are required to determine the real incidence of coronary lesions and the long-term outcome of the pulmonary valve in the systemic position.

Assessment of myocardial viability in patients with previous myocardial infarction by using single-photon emission computed tomography with a new metabolic tracer: [123I]-16-iodo-3-methylhexadecanoic acid (MIHA). Comparison with the rest-reinjection thallium-201 technique

OBJECTIVES

We compared the ability of rest single-photon emission computed tomography (SPECT) with [123I]-16-iodo-3-methylhexadecanoic acid (MIHA) and the thallium-201 (Tl-201) rest-reinjection technique to detect myocardial viability after infarction.

BACKGROUND

After myocardial infarction, MIHA frequently shows increased uptake in the areas with exercise Tl-201 defects (mismatch), even in patients with an irreversible Tl-201 reinjection defect. Whether such increased uptake is indicative of ischemic but viable myocardium is not known.

METHODS

We studied 38 patients who 1) underwent exercise SPECT Tl-201 with rest-reinjection and rest SPECT with MIHA before undergoing percutaneous transluminal coronary angioplasty (PTCA) of an infarct-related coronary artery, and 2) were found to have successful revascularization at follow-up angiography. The relation between SPECT results before PTCA and subsequent improvement in left ventricular wall motion was assessed.

RESULTS

A mismatch was evident before PTCA in 51 of 76 infarct-related segments and correlated with subsequent improvement in wall motion (overall accuracy 71%), even for the 27 segments whose exercise defects remained irreversible after Tl-201 reinjection (overall accuracy 81%). The finding of a mismatch clearly enhanced the results provided by the finding of > or = 50% Tl-201 uptake as determined at redistribution (p < 0.05), but not as determined at reinjection, although there was a trend toward a better specificity for the findings of a mismatch.

CONCLUSIONS

MIHA is an efficient marker of viability inside exercise-underperfused areas after infarction, even in patients with irreversible Tl-201 reinjection defects. Assessment by conventional SPECT of a mismatch between results obtained with a metabolic tracer (MIHA) and a flow tracer analyzed at exercise (Tl-201) as a marker of myocardial viability is a promising area of research.

[Effect of late revascularization of the responsible artery after infarction on left ventricular function and remodeling]

The effects of late angioplasty of the culprit artery after myocardial infarction on the decisive prognostic factors of left ventricular function and remodeling are not well known. When the culprit artery is narrowed but patent, angioplasty leads to improvement in segmental contractility and global left ventricular function: it does not seem to influence left ventricular end-diastolic volume. When the artery remains occluded, global and regional left ventricular function is also improved when the recanalised artery remains patent. Moreover, restoration of satisfactory artery patency prevents ventricular remodeling whereas in failed angioplasty or reocclusion, there is a progressive increase in left ventricular volume. However, these results observed in unselected patients could be improved: it would seem that the different beneficial effects only occur when there is residual myocardial viability; in the absence of signs of myocardial viability, the ventricular effects of limitations of angioplasty (incidence of restenosis or reocclusion in this specific context, lower primary success rate in complete arterial occlusion) explain the negativity of rare randomised studies comparing the outcome of left ventricular function depending on whether a conventional attitude or systematic revascularisation of the culprit artery is adopted.

[Anomalous origin of the left main coronary artery from the right coronary sinus and trajectory to the great vessels. Value of echocardiography in a child]

During a routine medical check-up, a pathological electrocardiogram was recorded in an asymptomatic 6 year old girl. The demonstration of coronary insufficiency by exercise stress testing and sestamib myocardio-scintigraphy led to the diagnosis of an anomalous origin of the left coronary artery. This vessel arose from the right coronary sinus and continued anteriorly to the main coronary artery. The data of the literature suggest that the risk of sudden death and of coronary insufficiency is associated with the passage of the left coronary artery between the aorta and pulmonary artery. The authors describe the anomalous origin of the left coronary artery and its trajectory with respect to the great vessels by echocardiography, using a high frequency transducer. The anterior direction of the left coronary artery in front of the main pulmonary artery may lead to ischaemia on effort even without stenosis at coronary angiography. Echocardiography may therefore be useful in children with positive exercise stress tests for diagnosing anomalous coronary vessels and their relationship with respect to the great vessels.

The usefulness of cardio-vascular visualization in the localization of mediastinal pheochromocytomas with I-131-MIBG

A case of malignant mediastinal paraganglioma showing moderate I-131-MetaIodoBenzylGuanidine (MIBG) uptake in the pericardiac region is presented. The patient had already undergone unilateral adrenalectomy with obvious clinical and biochemical findings of pheochromocytoma. The initial thoraco-abdominal CT and adrenal MRI were negative. The MIBG scan prior to the operation showed moderately increased uptake in the left adrenal region. No pheochromocytoma was found in the removed gland and the clinical signs persisted following the operation. The second MIBG scan after surgery showed a moderate left mediastinal uptake site by which it was difficult to rule out intracardiac localization. Without moving the patient, successive images of the tumor, myocardium and main mediastinal vessels were obtained by using the 24 hour activity of the initially injected 37 MBq Iodine-131-MIBG, 74 MBq Thallium-201 and 555 MBq Tc-99m-Human Serum Albumin (HSA), respectively. The superimposed bicolor images clearly showed the extracardiac localization of the tumor. The MRI scan confirmed this finding. Subsequent surgery found a malignant paraganglioma and metastatic mediastinal lymph nodes. We conclude that the visualization of the myocardium and the main mediastinal vessels with specific agents can be very useful in defining the exact location of I-131-MIBG detected mediastinal pheochromocytomas.

Long-term prediction of major ischemic events by exercise thallium-201 single-photon emission computed tomography. Incremental prognostic value compared with clinical, exercise testing, catheterization and radionuclide angiographic data

OBJECTIVES

This study sought to evaluate the prognostic role of exercise thallium-201 (Tl-201) single-photon emission computed tomography (SPECT) in patients with known or suspected coronary artery disease.

BACKGROUND

Compared with planar Tl-201 scintigraphy, Tl-201 SPECT allows enhanced assessment of myocardial perfusion abnormalities. However, the long-term prognostic value of exercise Tl-201 SPECT has not been ascertained and compared with that of other techniques of investigation.

METHODS

Predictors of ischemic events were sought in 217 patients with known or suspected coronary artery disease who underwent exercise Tl-201 SPECT, coronary angiography and rest radionuclide angiography and who initially received medical therapy. Predictive values were determined using Cox proportional hazards regression models.

RESULTS

During a mean (+/- SD) follow-up period of 70 +/- 19 months, 29 patients had a major ischemic event (cardiac death or myocardial infarction). Total extent of exercise defects was the best independent predictor by Tl-201 SPECT of major events (p < 0.001) and provided additional prognostic information compared with clinical, exercise testing and catheterization variables (p < 0.02). Extent of reversible Tl-201 SPECT perfusion defects provided additional prognostic information compared with extent of irreversible defects (p < 0.001) and was the sole Tl-201 SPECT variable providing additional prognostic information compared with radionuclide left ventricular ejection fraction (p < 0.02).

CONCLUSIONS

Total extent of exercise Tl-201 SPECT defects is a powerful long-term predictor of major ischemic events that enhances the prediction provided by clinical, exercise testing and coronary angiographic data. In view of its prognostic significance, extent of reversible Tl-201 SPECT defects might provide original information about improving prognosis by coronary revascularization.

Thallium-201 rest-reinjection and iodine-123-MIHA imaging of myocardial infarction: analysis of defect reversibility

Rest SPECT imaging with [123I]-16-iodo-3-methylhexadecanoic acid (MIHA) frequently shows an increased level of uptake in areas with irreversible defects on exercise 201TI SPECT. Such mismatch patterns between flow (201TI) and metabolic (MIHA) tracers might correspond to areas with ischemic but viable myocardium misidentified by 201TI imaging.

METHODS

Eighty-three patients with myocardial infarction underwent exercise SPECT 201TI with rest-reinjection and rest SPECT with MIHA. Defect areas on the exercise images were reversible on MIHA but not on 201TI reinjection images that were determined visually. The presence and extent of these areas were quantified from normalized uptake values for both tracers.

RESULTS

In areas with irreversible 201TI reinjection defects, MIHA detected exercise defect reversibility in 59% of patients. In areas with irreversible 201TI reinjection defects, the extent of visually determined defect reversibility on MIHA scans was related to the quantified extent of areas with 201TI uptake > or = 50% of normal; the correlation, however, was weak. In 86% of patients, areas with > or = 50% 201TI uptake were larger than those that were reversible on MIHA.

CONCLUSION

After myocardial infarction, rest SPECT with MIHA often enables visual detection of increased uptake in areas with irreversible 201TI reinjection defects.

Myocardial perfusion imaging with technetium-99m-Tc NOET: comparison with thallium-201 and coronary angiography

We compared TcN-NOET [bis(N-ethoxy, N-ethyl dithiocarbamato)nitrido 99mTc] and 201Tl images to estimate the utility of this compound in the detection of coronary artery disease (CAD).

METHODS

Twenty-five patients undergoing cardiac catheterization had stress-redistribution-reinjection 201Tl SPECT imaging, stress-delayed (2, 4 and 6 hr postinjection) and rest-delayed (4 hr postinjection) TcN-NOET SPECT imaging.

RESULTS

Nineteen patients had coronary stenosis > or = 50% and six were normal. Stress TcN-NOET and 201Tl imaging were concordant for the presence of CAD in 22/25 patients (88%, kappa = 0.76 +/- 0.20). The overall sensitivity of TcN-NOET SPECT imaging was 74% (14/19 patients) and 68% (13/19 patients) for 201Tl SPECT imaging. The specificity was 100% (6/6 patients) for both techniques. The overall agreement of TcN-NOET and 201Tl for the presence of disease in individual coronary arteries was 96% (72/75 arteries, kappa = 0.92 +/- 0.16). Segmental analysis of stress images showed a concordance in 211/225 segments (94%, kappa = 0.82 +/- 0.09). Comparison of the 4-hr images showed a concordance between 201Tl and TcN-NOET in 21/23 patients. Following TcN-NOET injection at rest, seven patients had a defect on the initial images, which had normalized 4 hr postinjection in four patients (57%).

CONCLUSION

Perfusion imaging with TcN-NOET and 201Tl gives comparable diagnostic information in patients undergoing exercise testing for assessment of CAD. Because of the normalization of myocardial activity 4 hr after injection in some patients, we conclude that TcN-NOET is a potential technetium compound equivalent to 201Tl.

Serial evaluation of dilated cardiomyopathy with exercise thallium-201 tomography: correlation with the evolution of left ventricular parameters

The purpose of this prospective study was to correlate (1) the initial findings of exercise thallium-201 tomography with the evolution of left ventricular parameters at long term follow-up in patients with dilated cardiomyopathy and (2) the changes of exercise thallium-201 tomography repeated 1 year later. We studied 19 men with dilated cardiomyopathy and normal coronary angiogram. Two patients died and three patients had heart transplantation during follow-up. The other 14 patients were assessed at baseline and 1-year follow-up. Thallium-201 tomograms were divided into 20 segments for each patient. Two groups were defined according to the evolution of left ventricular ejection fraction: group 1 (n = 7) had unchanged or decreased ejection fraction at follow-up (24 +/- 11% at baseline versus 22 +/- 11% at follow-up, ns) and group 2 (n = 7) had improved ejection fraction at follow-up (25 +/- 9% at baseline versus 49 +/- 8% at follow-up, P < 0.03). The number of total abnormal segments at stress were not statistically different at baseline between groups 1 and 2, and in group 1 between baseline and follow-up. Group 2 at follow-up had a reduced number of total abnormal segments (P < 0.03). The percentage of reversibility was similar in both groups at baseline and follow-up. On exercise thallium-201 tomography, neither the presence nor the reversibility of stress myocardial perfusion abnormalities can predict improvement of left ventricular ejection fraction in dilated cardiomyopathy. However, regression of dilated cardiomyopathy is accompanied by a reduction of stress myocardial perfusion abnormalities.

Comparison of right ventricular systolic function in idiopathic dilated cardiomyopathy and healed anterior wall myocardial infarction associated with atherosclerotic coronary artery disease

A case-controlled study assessed right ventricular (RV) systolic function in 10 patients with idiopathic dilated cardiomyopathy (IDC) and in 10 with healed anterior wall myocardial infarction associated with atherosclerotic coronary artery disease (CAD). Each patient was matched for sex, left ventricular ejection fraction +/- 5% and pulmonary artery mean pressure +/- 5 mm Hg. All patients had sinus rhythm and a left ventricular ejection fraction < 45%. A new, well-validated thermodilution technique was used to assess RV ejection fraction and volumes. RV ejection fraction was lower in the IDC than in the CAD group (25 +/- 14% vs 36 +/- 11%; p < 0.02). Linear correlations between RV parameters and pulmonary artery pressure were significantly present in both groups. However, the slopes of the equations were not statistically different. In comparison with healed anterior wall myocardial infarction with CAD and for similar levels of left ventricular dysfunction, RV systolic function appeared to be more altered in IDC.

Comparison of T1 estimation techniques in cardiac MRI

We have shown that the use of a simple combination of inversion recovery/spin-echo (IR/SE) sequences provides undeniably superior precision in quantitative in vivo myocardium T1 estimation than the standard multiple spin-echo approach. On a group of 25 healthy subjects, the T1 dispersion was, respectively, 3.8% for the IR/SE combination and 19.6% for the best SE pair combination. Moreover, repeated measurements were carried out on seven of the volunteers in order to assess T1 reproducibility. The mean intra-individual T1 precision was found to be 2.8% for the IR/SE pair and 20.0% for the best SE pair. The in vivo imaging work was supported and corroborated by a thorough treatment of the theoretical T1 errors. We also highlight the importance of quality control in quantitative MRI; a correction being required in the SE sequences to bring measured signal intensities into line with those predicted from simple theory.

Radionuclide assessment of regional differences in left ventricular wall motion and myocardial perfusion in idiopathic dilated cardiomyopathy

Regional variations in left ventricular contractility and myocardial perfusion are frequent in idiopathic dilated cardiomyopathy and might result from an increase in left ventricular wall stress responsible for regional wall motion abnormalities. The aim of the study was to perform radionuclide studies in patients with idiopathic dilated cardiomyopathy to assess regional left ventricular wall motion and myocardial perfusion abnormalities in this myocardial disease. We studied 29 men referred with idiopathic dilated cardiomyopathy and normal coronary angiograms. Rest radionuclide left ventriculography and exercise thallium-201 tomography were performed in all patients. The thallium-201 tomograms were divided into 20 segments for each patient. Mean left ventricular ejection fraction was 27 +/- 11%; 17 patients had diffuse hypokinesia (mean left ventricular ejection fraction: 24 +/- 9%) and 12 patients had predominant regional hypokinesia (mean left ventricular ejection fraction: 32 +/- 12%). Of all 580 tomographic segments, 186 had a reduction of thallium-201 uptake at exercise. Among them, reversibility was found in 53%. On the whole, 68% (158/232) of anterior, inferior and apical segments had a perfusion abnormality, compared with 8% (28/348) of septal and lateral segments (P < 0.0001). Left ventricular wall motion and myocardial perfusion abnormalities are heterogeneous and not evenly distributed in dilated cardiomyopathy. The alterations are predominant on the myocardial regions delineating the antero-posterior axis of the left ventricle. These findings suggest the possible role of increased left ventricular wall stress on this axis.

Usefulness of exercise SPECT-thallium to detect asymptomatic restenosis in patients who had angina before coronary angioplasty

The usefulness of exercise single photon emission computed tomography (SPECT)-thallium for detecting asymptomatic restenosis was assessed prospectively in 62 patients with angina before angioplasty, who underwent < or = 6-month re-angiography and exercise SPECT-thallium imaging. Among patients with restenosis, nine had recurrence of angina but eight did not. These two subgroups had equivalent percentages of restenosis (71 +/- 16% vs 64 +/- 16%, NS) and extent of reversible thallium defects (2.8 +/- 1.7 vs 4.1 +/- 2.6, NS), and both subgroups had poorer hemodynamic responses to exercise compared with patients without restenosis (maximal) rate-pressure product [X 100], 258 +/- 54 and 239 +/- 33 vs 302 +/- 61; p < 0.05 and p < 0.01, respectively). Exercise testing detected fewer patients with restenosis compared to exercise SPECT-thallium imaging, especially among asymptomatic patients (25% vs 100%, p < 0.005). Asymptomatic restenosis occurs frequently, induces an amount of stress ischemia equivalent to that of symptomatic restenosis, and is efficiently detected by exercise SPECT-thallium with rest-reinjection but not by exercise testing.

[Cardiac arrest reversed: causes and treatments]

The aim of this study was to report the probable mechanism of resuscitated cardiac arrest without acute myocardial infarction. Fifty-seven cases were recensed but the arrest was only documented in 44 subjects. Systematic non-invasive investigations and programmed stimulation showed that the diagnosis of cardiac arrest was probably false in 5 patients and, in the others, that a ventricular arrhythmia was probably the cause (63%). The occurrence of cardiac arrest under antiarrhythmic therapy may reveal an underlying abnormality requiring specific therapy (3/8). The absence of cardiac disease did not exclude the risk of VF (3 cases). When reproducible, ventricular arrhythmias were present during programmed stimulation, the prognosis was good if the arrhythmia could not be induced under antiarrhythmic therapy. It was easier to find an effective treatment for inducible ventricular fibrillation-flutter (13/17) than for inducible ventricular tachycardia (7/17). The prognosis was poor if the arrhythmia was unchanged during programmed stimulation under antiarrhythmic therapy and non-pharmacological treatment was required.

Synchronized inversion recovery-spin echo sequences for precise in vivo T1 measurement of human myocardium: a pilot study on 22 healthy subjects

An ECG-triggered, two-sequence MRI technique is proposed for the precise measurement of proton T1 relaxation times of the human myocardium at a field strength of 0.5 T. The combination of an inversion recovery (IR) sequence and a spin echo (SE) sequence is not new. It is, however, rarely used in quantitative in vivo cardiac studies. Our approach employs a synchronization of the 90 degrees read pulse to the systolic period. In a study of 22 healthy volunteers, the globally measured T1 value was estimated to be 714 +/- 23 ms. Four of the volunteers also underwent additional imaging scans for the purposes of reproducibility assessment. The T1 precision was found to be 3.9 +/- 1.1% for the IR/SE combination and 16.9 +/- 5.3% for a combination of SE sequences. Total imaging time for the IR and SE sequences was 19.2 +/- 3.0 mins. The relative rapidity of this classic technique and the T1 precision obtained give this technique an obvious application in the discrimination of normal and diseased myocardium. In the same study, valuable supplementary tissue characterization is provided by T2, calculated from the SE sequence. T2 was evaluated to be 50 +/- 3 ms.

Results of percutaneous transluminal coronary angioplasty of either the left anterior descending or left circumflex coronary artery in patients with chronic total occlusion of the right coronary artery

The acute and long-term results of percutaneous transluminal coronary angioplasty (PTCA) of the left coronary artery in 106 patients (group 1) with chronic occlusion of the right coronary artery were compared with those of 106 patients matched for sex (92 male) and age (56 +/- 10 years) undergoing left PTCA with a normal right coronary artery (group 2). Before the procedure, group 1 had more unstable angina (42 vs 29%; p < 0.05), more frequent prior myocardial infarction (80 vs 25%; p < 0.001), and a lower left ventricular ejection fraction (56 +/- 10% vs 65 +/- 11%; p < 0.005). Acute results were not different in the 2 groups with respect to primary success (group 1: 93%; and group 2: 89%) and complications (group 1: 2 with emergency coronary surgery, and 4 with periprocedural myocardial infarction and no death; and group 2: 1 with emergency coronary surgery, 1 death, and 3 with periprocedural myocardial infarction). At 6 months, 79 patients in group 1 and 71 patients in group 2 had reangiography; the rate of restenosis was 35% in group 1 and 42% in group 2. In both groups, left ventricular ejection fraction increased significantly in patients without restenosis (58 +/- 12% vs 63 +/- 10%, p < 0.001 [n = 44] in group 1; and 66 +/- 9% vs 70 +/- 10%, p < 0.001 [n = 29] in group 2). In group 1, improvement was significant only for patients without collaterals to the occluded right coronary artery (59 +/- 10% vs 66 +/- 7%; p < 0.003 [n = 24]).(ABSTRACT TRUNCATED AT 250 WORDS)

Percutaneous transluminal coronary angioplasty in patients more than 75 years old: early and long-term results

Over 4 yr, 102 consecutive patients more than 75 yr old (56 men, 46 women; mean age 78 +/- 3 years, range: 76-89 years) underwent 120 percutaneous transluminal coronary angioplasty procedures. At baseline, 86% had severe anginal symptoms (Canadian class III or IV), 43% had a history of prior myocardial infarction; 61% had multivessel coronary artery disease, and mean left ventricular ejection fraction was 60 +/- 11%. Calcifications were observed on 66% of the dilated arteries. A total of 158 vessels (1.3 vessel per procedure) were attempted: 1 vessel in 89 procedures (74%), 2 vessels in 24 (20%) and 3 vessels in 7 (6%). The primary success rate was 80% per lesion (126/158) and 77% per procedure (92/120). Complications included 3 deaths (3%), 9 Q-wave infarctions (7.5%) and there was no emergency coronary bypass surgery. The primary success rate was significantly related to the absence of coronary calcifications on the dilated segment (88% versus 75%, p < 0.05) and to the initial patency of the dilated artery (subtotal stenosis: 83% versus total occlusion: 53%, p < 0.05). Follow-up data were obtained in the 79 consecutive patients with a duration of follow-up exceeding 8 months. The mean duration of follow-up was 23 +/- 13 months (range 8 to 61 months). No patient was lost to follow-up; 11 patients died (cardiac causes: 7), 2 had a non-fatal infarction, 7 had aortocoronary bypass surgery and 18 had repeat percutaneous transluminal coronary angioplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

Right ventricular overload and induced sustained ventricular tachycardia in operatively "repaired" tetralogy of Fallot

The aim of the study was to evaluate the main predictors of the inducibility of sustained ventricular tachycardia (VT) in patients with repaired tetralogy of Fallot. Thirty-five patients (age 12 +/- 6 years) underwent right-sided cardiac catheterization, echocardiography, radionuclide angiography and ventricular stimulation; 10 had (group 1) and 25 had no (group 2) sustained VT. Group 1 patients were significantly older at the time of surgery and had longer follow-up periods (7 +/- 3 vs 4 +/- 4 years, p less than 0.02; and 12 +/- 4 vs 5 +/- 2 years, p less than 0.001, respectively). Right ventricular (RV) systolic pressure, end-systolic and end-diastolic normalized RV volumes were higher in group 1 (48 +/- 14 vs 38 +/- 11 mm Hg, p less than 0.05; 1.23 +/- 0.2 vs 0.86 +/- 0.17, p less than 0.001; and 2.35 +/- 0.37 vs 1.70 +/- 0.22, p less than 0.001, respectively). RV end-diastolic pressure, left ventricular and RV ejection fractions were similar in the 2 groups. A stepwise discriminant analysis was made to predict patients with inducible sustained VT (group 1): Time period from surgery to follow-up (p less than 0.001), normalized RV end-systolic volume (p less than 0.002) and RV systolic pressure (p = 0.01) were higher in group 1 and allowed classification of 90% of patients in group 1 and 96% in group 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Evolution of myocardial ischemia and left ventricular function in patients with angina pectoris without myocardial infarction and total occlusion of the left anterior descending coronary artery and collaterals from other coronary arteries

Repeated episodes of myocardial ischemia might lead to progressive impairment of left ventricular (LV) function. This radionuclide study assessed myocardial ischemia and LV function several years after documented coronary occlusion without myocardial infarction. Over 5 years, 24 consecutive patients, who underwent cardiac catheterization for angina pectoris without myocardial infarction, had isolated total occlusion of the left anterior descending coronary artery with well-developed collateral vessels. Five patients were successfully treated by coronary bypass grafting and 3 by coronary angioplasty. Among the 16 medically treated patients, 1 was lost to follow-up and 1 died (extracardiac death). The mean (+/- standard deviation) follow-up (14 patients) was 48 +/- 15 months. At follow-up, 8 patients still had clinical chest pain, 11 received antianginal therapy, 4 patients had no stress ischemia and the other 10 had greater than or equal to 1 sign of stress ischemia. All patients had a normal LV ejection fraction at rest (mean 60 +/- 3%; range 55 to 65%). Collateral circulation preserves LV function at the time of occlusion and, in some cases, prevents the development of myocardial ischemia; in patients with persisting myocardial ischemia after well-collateralized coronary occlusion, LV function is not impaired at long-term follow-up.

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.

Role of ancillary properties of beta-adrenoceptor antagonists in protecting the heart from anoxia

The mechanism of the cardioprotective action of beta-blocking drugs against anoxia or ischemia is still not clear. We used beta-blockers (5 x 10(-7) M) of various pharmacodynamic profiles in a model of isolated, perfused working guinea pig heart subjected to 20 min of anoxia to study this. The cardioprotective effects were evaluated by measuring the recovery of the flow indices after 15 min of reoxygenation. There was a significant cardioprotective action (as measured by the effect on stroke volume recovery and on recovery of other flow and work indices) of the beta-blocking properties (nadolol, P less than 0.05), of the membrane-stabilizing property [+)-propranolol, P less than 0.05) and of a combination of these two properties with (+/-)-propranolol, which had a significantly greater effect than nadolol (P less than 0.05). The addition of weak (acebutolol) or strong (pindolol) intrinsic partial agonist activity had no clear unfavourable effect, as the degree of cardioprotection was comparable with that obtained with (+/-)-propranolol. The stroke volume recovery (percent recovery after anoxia) in the control hearts was 42.57 +/- 12.75 compared to 54.84 +/- 6.94 in hearts pretreated with nadolol, 62.99 +/- 11.41 with (+)-propranolol, 71.02 +/- 11.36 with (+/-)-propranolol, 72.63 +/- 13.08 with acebutolol and 68.01 +/- 15.42 with pindolol. In vitro heart protection from anoxia with beta-blockers would appear to be related to beta-blocking activity and/or membrane stabilizing property but not a function of partial agonist activity. These ancillary properties of beta-blockers should thus be taken into account in studies on cardioprotection.