[VO2 max: technique and practical importance]. / VO2 max: technique et intérêt pratique.

NORMAL SITUATION: Ergonometric spirometric measurement of O2 consumption and CO2 production (VO2max) can be used to assess adaptation of the oxygen transportation system to exercise. In the normal situation, the capacity to sustain exertion in everyday physical activities depends directly on the capacity of this system to adapt, i.e. the level of physical training. PATHOLOGICAL CONDITIONS: In diseased patients, this test can measure the degree of non-adaptation and the efficacy of compensatory mechanism of the oxygen transport system. It can be used as a pathophysiological diagnostic tool for following divers disease states, particularly heart conditions. Spirometry is a key test used in all cardiology centers to assess the degree of heart failure.

Coronary artery response to cold-pressor test is impaired early after operation in heart transplant recipients.

OBJECTIVES: The aim of the present study was to evaluate the coronary vasomotor response to the cold-pressor test within 3 months after heart transplantation. BACKGROUND: Normal epicardial coronary arteries dilate in response to sympathetic stimulation evoked by the cold-pressor test. In transplant recipients, abnormal coronary vasomotion has been described shortly after operation. METHODS: Fourteen heart transplant recipients were compared 52 +/- 15 days (mean +/- SD) after operation with 10 control subjects. All had angiographically normal epicardial coronary arteries. Coronary blood flow velocity was measured with a Doppler catheter placed in the proximal left anterior descending coronary artery. Four segments in each patient were analyzed by quantitative coronary angiography to assess the diameter changes during the cold-pressor test and after intracoronary injection of isosorbide dinitrate. RESULTS: Coronary flow velocity increased similarly during the cold-pressor test in control subjects and in transplant recipients, from 7.5 +/- 2.3 to 11.0 +/- 3.9 cm/s and from 10.3 +/- 3.2 to 13.7 +/- 4.8 cm/s (both p < 0.01). In control subjects, 39 of 40 segments analyzed dilated during the cold-pressor test. In transplant recipients, 48 of 56 segments analyzed did not change or constricted. The mean epicardial coronary diameter increased significantly during the cold-pressor test in control subjects (+13 +/- 6%, p < 0.001), whereas it did not change significantly in transplant recipients (-2 +/- 9%, p = NS). In transplant recipients, isosorbide dinitrate elicited coronary vasodilation similar to that in control subjects. CONCLUSIONS: These data indicate that in human transplanted denervated hearts, coronary vasodilation in response to sympathetic stimulation by cold exposure is impaired shortly after operation.

Orthotopic cardiac transplantation with direct caval anastomosis: is it the optimal procedure?

Total excision of the right atrium with a minimal cuff of left atrium remaining around the four pulmonary veins, followed by direct anastomoses on venae cavae, has been proposed as an alternative to the standard procedure described by Shumway and Lower for orthotopic cardiac transplantation. To investigate whether this "anatomic" transplantation should be proposed as the optimal procedure, we prospectively randomized 78 patients having 81 procedures since 1991 into two groups: group I, standard transplantation (n = 40), and group II, "anatomic" transplantation (n = 41). The two groups were statistically similar in recipient age, sex, weight, disease, and status at the time of transplantation. Also similar were donor age, sex, weight, and drug dependency at the time of harvesting. All patients could be weaned from cardiopulmonary bypass with comparable graft ischemic times (group I, 136 +/- 46 minutes; group II, 138 +/- 51 minutes). Immediate recovery of sinus rhythm occurred in 20 cases of group I and 36 cases of group II. Delayed recovery of sinus rhythm in the first postoperative week occurred in 15 cases of group I and 5 cases of group II. Persistence of atrial arrhythmia occurred in 5 cases of group I and never in group II. These differences were highly significant (p < 0.001). Postoperative hemodynamics showed a higher cardiac index at day 1 in group II (4.12 +/- 0.85 L/min per square meter) than in group I (3.77 +/- 0.65 L/min per square meter) (p = 0.04). There were 13 early deaths in group I and 8 early deaths in group II. One death in group I was related to an acute atrioventricular block at 3 weeks with no evidence of cardiac rejection at histologic examination. Two patients in group I (5%) required definitive pacemaker implantation for prolonged sinus node dysfunction. Echocardiographic and Doppler studies of survivors have been performed 2 to 3 months after transplantation. Right atrial area was significantly reduced (p < 0.01) in group II (18 +/- 4.7 cm2) versus group I (24 +/- 7 cm2), as was left atrial area (group I, 24 +/- 4.5 cm2; group II, 20 +/- 5 cm2) (p = 0.01). Mild tricuspid regurgitation was observed in 82% of group I patients versus 57% of group II patients (p < 0.05), inasmuch as mitral regurgitation was comparable (71% in group I, 67% in group II).(ABSTRACT TRUNCATED AT 400 WORDS)

[Echocardiographic anomaly of septal contraction after open heart surgery]. / Anomalie échocardiographique de la contraction septal après chirurgie à coeur ouvert.

The function of the interventricular septum (IVS) was studied by M mode echocardiography one month after open-heart surgery in 256 patients with valvular heart disease and without any accepted mechanism of abnormal septal motion. Systolic anterior motion of the IVS was observed in 44% of all the patients and was found to be more common in patients undergoing corrective aortic procedures (64%) than in patients undergoing corrective mitral (36%, p less than 0,01) or mitro-aortic (45% , p less than 0,01) procedures. In technically very adequate studies of 43 patients (33 with systolic anterior motion of the IVS) and 10 normal controls, the following observations were made: - the systolic anterior motion of the IVS was greater after aortic procedures than after mitral ones (-5,64 +/- 1,44 mm, and -2,14 +/- 2,66 mm, p less than 0,005); - patients with systolic anterior motion of the IVS had reduced percentage systolic septal thickening (30,9 +/- 19,0%, p less than 0,02) and normal controls (56,1 +/- 21,0%, p less than 0,005); -the systolic anterior motion of the posterior epicardial echo was more pronounced in post-operative patients, both with abnormal (7,9 +/- 1,8 mm) and normal (7,8+/- 2,2 mm) septal motion, than in normal controls (4,8 +/- 0,7 mm p less than 0,001 and p less than 0,005, respectively); - no other known cause of systolic anterior septal motion were present in the post-operative patients. In conclusion, patients undergoing cardio-pulmonary bypass demonstrated increased systolic anterior motion of the whole heart, which was thought to be related to the partial removal and/or the non-closure of the pericardium. However, this feature was not the only mechanism for the abnormal post-operative motion of the IVS, as reduced contraction of the IVS was always found in these patients. This finding could be ascribed to myocardial per-operative injury, the exact nature of which remains unknown.

Pulsus alternans in regionally hypoxic ventricles of open-chest dogs: regional mechanical alternation of potentiation and attenuation of the inotropic state.

Sustained mechanical alternation appeared after a spontaneous premature ventricular contraction in 6 open-chest dogs during the perfusion of the left circumflex coronary artery by Krebs-Henseleit solution equilibrated with 5% CO2 and 95% N2. The animals were instrumented with a catheter in the left ventricle and ultrasonic crystals in hypoxic and control segments. Left ventricular systolic pressure was significantly higher in the strong than in the weak beats with no significant difference of end-diastolic lengths in hypoxic and control segments. In hypoxic segments, systolic shortening was significantly larger in strong beats (11.9 +/- 1.9%) as compared with weak beats (5.1 +/- 1.6%) and with control beats preceding the premature ventricular contraction (9.7 +/- 1.6%) but the postextrasystolic beat was larger (17.9 +/- 1.3%). There was no significant change of systolic shortening in control segments during mechanical alternation which appears thus as a regional phenomenon which cannot be explained by the Starling mechanism: instead, alternation is attributed to a change of excitation-contraction coupling after a premature contraction with alternation of potentiation and attenuation of the inotropic state.

[The left ventricle at different stages of a two steps mechanical overloading. Electron microscopic study in the rat (author's transl)]. / Le ventricule gauche aux différentes étapes d'une double surcharge mécanique. Etude au microscope électronique chez le rat.

The left ventricle myocardium of rats subjected to a two steps mechanical overloading (abdominal aorta constriction + aortic insufficiency) was examined in the light and electron microscopes at several stages of the load, and particularly after 3 to 6 months when the animals exhibited congestive heart failure. In these conditions, the heart weight exceeded the control by more than 100%. In the later stages, the absence of parallelism between heart weight and cell diameter was compatible with a process of hyperplasia. Cellular lesions looking like recent were found more and more frequently with time. Within apparently normal cells proliferation of small mitochondria, nucleoli and Golgi apparatus are compatible with some deficit in energy balance, which is usually encountered only in early stages of the load.

[The left ventricle at different stages of a two steps mechanical overloading. Electron microscopic study in the rat (author's transl)]. / Le ventricule gauche aux différentes étapes d'une double surcharge mécanique. Etude au microscope électronique chez le rat.

The left ventricle myocardium of rats subjected to a two steps mechanical overloading (abdominal aorta constriction + aortic insufficiency) was examined in the light and electron microscopes at several stages of the load, and particularly after 3 to 6 months when the animals exhibited congestive heart failure. In these conditions, the heart weight exceeded the control by more than 100 %. In the later stages, the absence of parallelism between heart weight and cell diameter was compatible with a process of hyperplasia. Cellular lesions looking like recent were found more and more frequently with time. Within apparently normal cells proliferation of small mitochondria, nucleoli and Golgi apparatus are compatible with some deficit in energy balance, which is usually encountered only in early stages of the load.

Development and reversal of pressure-induced cardiac hypertrophy. Light and electron microscopic study in the rat under temporary aortic constriction.

Light and electron microscopy, combined with morphometry, were utilized to study myocardial cell modifications induced by a temporary abdominal aortic constriction in the rat. During the early stage of active hypertrophy, cell enlargement in the subendocardial layers of the left ventricle was predominant. This enlargement may be partly due to intracellular edema, characteristic of cell damage. Degenerative foci leading to fibrous scars were found primarily in the subendocardium and midwall layers. The times taken by the different cell structures to adapt to modifications of the load were rather different; some adapted very rapidly (nucleoli, intercalated discs), while others were much slower (cell diameter, mitochondria).

[Blood digoxin and treatment of heart failure in aged patients]. / Digoxinémie et traitement de l'insuffisance cardiaque du sujet âgé

Serum digoxin level was determined by radioimmunoassay in 76 elderly in-patients (age: 76.1 +/- 1.0) which were treated by digoxin without any evidence of toxicity. Digoxin levels was related to blood nitrogen (p less than 0,01); on the other hand, no relationship between others factors influencing the digoxin bioavailability (age, body weight, associated drug) and digoxin levels could be found. Therapeutic effectiveness, as estimated by ventricular rate and signs and symptoms, was not dependent of digoxin levels. In patients with higher functional class (III and IV NYHA), however, digoxin level was generally demonstrated to be increased. Digoxin levels were lower in patients with coronary heart disease (1.71 +/- 0,22 ng/ml; n = 16) than in patients with right ventricle overload (2.94 +/- 0,74 mg/ml; n + 7 - p less than 0.05). Because of the very large scattering of digoxin levels, digoxin determination seems to be useful in measuring individual bioavailability and therapeutic effectiveness, and leading to the best base line of any individual treatment.

[Anomalous ventricular contractile performance in experimental chronic aortic insufficiency in the dog]. / Anomalie de la performance contractile ventriculaire dans l'insuffisance aortique expérimentale chronique chez le chien

Hemodynamics and right (RV) and left (LV) ventricular performances of anaesthetized, closed-chest animals were studied in normal control dogs (N) and in dogs with aortic insufficiency (AI), the latter intervention being performed 33 months before verification. In dogs with AI, LV was hypertrophied (N = 49.6 +/- 6.3 g; AI = 98.7 +/- 10.1, p less than 0.001); forward stroke volume was slightly decreased (N = 20.0 +/- 2.2 ml; IA = 14.6 +/- 5.4 ml, p = NS);LV and diastolic pressure was increased (N = 9.4 +/- 1.4 mmHg; IA = 16.7 +/- 2.9, p less than 0.05); both RV and LV myocardial performace index (e.g. dP/dt max, peak VCE, Vmax) were normals. Relative pressure/velocity of shortening and wall stress/velocity of shortening relationships, however, were decreased, when measured during L.V. isovolumetric beats. LV stiffness of arrested heart was increased in proportions with hypertrophy extent. Thus, myocardial performance of chronically volume-overloaded heart appears to be depressed before the stage of the circulatory failure.

[Pulmonary embolism and preventive anticoagulant treatment in hospitalized elderly patients. Statistical study of their respective risks]. / Embolies pulmonaires et traitement anticoagulant préventif chez les malades âgés hospitalisés. Etude statistique de leurs risques respectifs

Pulmonary embolism and preventive anticoagulant therapy of ederly patients in hospital. Statistical survey of their respective risks. The incidence of pulmonary embolism as a cause of death seems the higher as its strikes old people (above 60) affected by cardiovascular diseases and who are bed tied; the interest of preventive anticoagulant treatment (PAT) remains controversial. This matter has been studied over a period of 5 years from the files of a geriatric cardiology department; 455 anatomo-clinical documents have been set up. This survey confirms the frequency of mortality by pulmonary embolism (23,9 %) and its diminution under long-term preventive anticoagulant treatment 6,6 %). The anticoagulant therapy does not increase the risk of haemorrhagic accidents, from the point of view of frequency, but slightly increases it if one considers the number of days spent in hospital. As a conclusion, the preventive anticoagulant treatment seems positive insofar as contra-indications are strictly observed, in particular the digestive ones. The mechanism of some hemorrhagic accidents with or without PAT remains sometimes difficult to explain.

Rat myocardial mechanics during pressure-induced hypertrophy development and reversal.

Moderate cardiac hypertrophy (CH) was produced in rats by abdominal aorta constriction for 5, 8, 15, 21, and 28 days. Aortic constriction release after 5, 8, and 15 days led to CH regression, which was complete within 15 days. A study of left ventricular papillary muscle mechanics during CH development demonstrated an early but transitory decrease in both maximum isometric force (Po) and maximum muscle shortening velocity (max V); in addition, the time-to-peak tension increased, and there was a decrease in isometric relaxation rate and in force-frequency relationship (negative staircase.) After CH regression, isometric relaxation and negative staircase were similar to controls, whereas the prolonged duration of contraction persisted. After release of the aortic constriction at 8 and 15 days, Po and max V were normal; however, after the earlier release (5 days), Po was higher than control, when muscle thickness was taken into consideration. These findings suggest 1) that an alteration in muscle mechanics may be related to the hypertrophy itself; 2) that anomalous excitation-contraction coupling might persist after CH regression.

Myocardial mechanics at various stages of the cardiac hypertrophy induced by a transitory work load in the rat.

Cardiac hypertrophy was induced in rats by abdominal aortic constriction lasting 5-28 days. In other rats, release of aortic constriction after 5 or 15 days led to hypertrophy regression, which was completed within 15 days. Left ventricular papillary muscle study during cardiac hypertrophy demonstrated an early but transitory decrease of tension development and shortening velocity, a prolonged contraction duration, a slowed relaxation, and a reduced response to changes in the stimulation rate. After hypertrophy regression, the prolongation of contraction persisted; mechanical performance was similar to control, except for increased peak isometric tension in early released animals. These findings indicated that anomalous excitation-contraction coupling may be related to the hypertrophy process itself and that prolonged contraction could act as a compensatory mechanism.