Postoperative exercise tolerance after aortic valve replacement by small-size prosthesis: functional consequence of small-size aortic prosthesis.

OBJECTIVES: The objective of this study was to determine whether a small-size valve prosthesis contributes to exercise intolerance, as assessed by VO2 measurement during an exhaustive cycle ergometer exercise. BACKGROUND: The determinants of exercise capacity after mechanical aortic replacement are not well known. The selection of small valve sizes has, however, been described as an independent predictor of exercise intolerance as assessed by exercise duration. Maximal oxygen uptake (VO2max) is a good index of exercise tolerance. METHODS: Fourteen patients were eligible, with a mean age of 62 +/- 6 years. Before surgery, the mean left ventricular ejection fraction (LVEF) was 73 +/- 8%. Two valve types with small diameter (19 to 21 mm) were used: Medtronic Hall and St Jude Medical. A healthy sedentary control group (n = 14) paired for age, weight and size was constituted. After one year of follow-up, cardiorespiratory tests were performed. In addition, the gradients through the prostheses were determined by continuous pulse Doppler at rest and immediately after the cardiorespiratory test. RESULTS The exercise tolerance was not significantly different between the control group and patient group: VO2 peak (21.7 vs. 20.4 ml/kg/min; p = 0.42), workloads (115 vs. 93 W; p = 0.13) and ventilatory parameters were similar. The mean and peak gradients at rest and during exercise were not correlated with VO2max. CONCLUSIONS: Valve replacement by small aortic prosthesis does not seem to be a factor of exercise intolerance as assessed by VO2max in patients without LVEF dysfunction before surgery.

[Ventricular tachycardia due to branch to branch re-entry]. / Tachycardies ventriculaires par rentrée de branche a branche.

Ventricular tachycardia due to branch to branch re-entry constitutes a rare clinical entity. This circuit is remarkable by the fact that it is made up of the branches or hemi-branches of the bundle of His bifurcation. They occur under specific conditions, with a combination of left ventricular dilatation and atrioventricular or intraventricular conduction defects. They are also very often found in Steinert's disease. A positive diagnosis can sometimes be difficult and relies on a variety of factors. Recording of the His potential shows His activity preceding each ventriculogram, and variations in spontaneous cycles between 2 ventriculograms preceded by variations between the 2 His potentials. Atrial capture without modification of the QRS is possible, but fusion excludes the diagnosis. Drug therapy is only slightly effective, and the best treatment is ablation of the right branch of the bundle of His, which stops the tachycardia definitively.

Comparison of direct coronary stenting with and without balloon predilatation in patients with stable angina pectoris. BET (Benefit Evaluation of Direct Coronary Stenting) Study Group.

The purpose of this study was to compare the effects of stent placement with and without balloon predilatation on duration of the procedure, reduction of procedure-related costs, and clinical outcomes. Although preliminary trials of direct coronary stenting have demonstrated promising results, the lack of randomized studies with long-term follow-up has limited the critical evaluation of the role of direct stenting in the treatment of obstructive coronary artery disease. Between January and September 1999, 338 patients were randomly assigned to either direct stent implantation (DS+; 173 patients) or standard stent implantation with balloon predilatation (DS-; 165 patients). Baseline clinical and angiographic characteristics were similar in the 2 groups. Procedural success was achieved in 98.3% of patients assigned to DS+ and 97.5% of patients assigned to DS- (p = NS), with a crossover rate of 13.9%. Compared with DS-, DS+ conferred a dramatic reduction in procedure-related cost ($956.4 +/- $352.2 vs $1,164.6 +/- $383.9, p <0.0001) and duration of the procedure (424.2 +/- 412.1 vs 634.5 +/- 390.1 seconds, p < 0.0001). At 6-month follow-up, the incidence of major adverse cardiac events including death, angina pectoris, myocardial infarction, congestive heart failure, repeat angioplasty, or coronary artery bypass graft surgery was 5.3% in DS+ and 11.4% in DS- (p = NS). Multivariate analysis demonstrated that major adverse cardiac events rates were related to stent length of 10 mm (relative risk [RR] 3.25, 95% confidence intervals [CI] 1.36 to 7.78; p = 0.008), stent diameter of 3 mm (RR 2.69, 95% CI 1.03 to 7.06; p = 0.043), and complex lesion type C (RR 2.83, 95% CI 1.02 to 7.85; p = 0.045). Thus, in selected patients, this prospective randomized study shows the feasibility of DS+ with reduction in procedural cost and length, and without an increase in in-hospital clinical events and major adverse cardiac events at 6-month follow-up.

Cardiopulmonary exercise testing. Determinants of dyspnea due to cardiac or pulmonary limitation.

The aim of this study was to bring to light new and simple criteria, obtained during cardiopulmonary exercise testing, in order to demonstrate in patients the cardiac or the pulmonary origin of a comparable exertional dyspnea. Forty male subjects were compared, who exercised with a 30-W/3-min protocol and were divided into three groups: the cardiac heart failure (CHF) group (n = 15), the chronic obstructive lung disease (COLD) group (n = 15), and the control group (n = 10). The two groups of patients differed totally from the control group concerning their spirometric values at rest and a clear inability during effort which was confirmed by all the studied cardiopulmonary parameters at maximal exercise. The CHF and COLD groups differed slightly concerning their maximum symptom-limited oxygen uptake, only when related to body mass (13.26 +/- 0.69 ml/kg/min in CHF group, 17.05 +/- 1.59 ml/kg/min in COLD group; p < 0.05), and concerning their maximum ventilatory equivalent for oxygen which tended to be higher in the CHF group in comparison with the COLD group (p = 0.082). Furthermore, and as foreseen, the two groups of patients clearly differed at maximum exercise concerning the ventilatory reserve respiratory parameter (49.73 +/- 3.18 percent in CHF group, 8.38 +/- 5.85 percent in COLD group; p < 0.01). On the other hand, they did not differ concerning cardiac parameters or those considered as such (maximum heart rate [HR], HR reserve, HR response, maximum O2 pulse measurement). While their maximum ventilation was similar in the CHF and COLD groups, a difference in adaptation during exercise was found by observing their breathing pattern. In the CHF group, this was demonstrated by a significantly lower breathing frequency at maximum exercise (31.24 +/- 1.53 beats/min vs 37.75 +/- 2.24 beats/min; p < 0.05) and a tidal volume that tended to be higher at maximum exercise (p = 0.077) and significantly higher at 60-W work load (p < 0.05). This work shows that the study of ventilatory reserve and breathing pattern during exercise testing allows one to discriminate if dyspnea on exertion in patients is due to cardiac or respiratory disease.

Comparison of myoglobin and creatine kinase MB levels in the evaluation of myocardial injury after cardiac operations.

Myoglobin was studied in 40 patients before, during, and after cardiac operations and was compared to the MB isoenzyme of creatine kinase to identify its possible role as a marker of perioperative myocardial damage. Myoglobin reached peak values during cardiac arrest in all patients and was significantly higher immediately after administration of the anesthetics, during cardiac arrest, and until the sixth postoperative hour in eight patients with a perioperative myocardial infarction. By contrast, the MB isoenzyme of creatine kinase reached peak values at the fourth postoperative hour and was significantly higher in patients with perioperative myocardial infarction from the fourth to the tenth postoperative hours. We conclude that myoglobin is a valuable marker of perioperative myocardial damage and is an earlier and more specific marker of perioperative myocardial infarction than creatine kinase MB.

Myosin: a highly sensitive indicator of myocardial necrosis after cardiac operations.

Plasma levels of ventricular myosin fragments, determined with monoclonal antibodies to myosin heavy chains, were studied in 27 patients after cardiac operations (17 aorta-coronary bypass grafts and 10 valve replacements) to assess their possible role as a marker of perioperative myocardial necrosis. Five patients had perioperative myocardial necrosis after aorta-coronary bypass grafts as indicated by changes in the electrocardiogram and elevated levels of the MB isoenzyme of creatine kinase. Six more patients were also studied after thoracic operations performed by the same sternotomy approach. After cardiac operations, myosin levels increased from postoperative day 3 and reached peak values on day 7. Peak myosin values in patients with perioperative myocardial necrosis after aorta-coronary bypass grafting were significantly higher than in patients after an identical operation but without perioperative myocardial infarction (3793 +/- 592 versus 369 +/- 47 ng/ml; p less than 0.001). These results suggest that plasma myosin is a sensitive marker of myocardial necrosis. Furthermore, peak plasma levels of ventricular myosin after coronary bypass grafting without myocardial infarction (mean value 369 +/- 47 ng/ml) were not significantly different from peak levels after thoracic operations (mean value 253 +/- 52 ng/ml), whereas they were significantly higher after valve replacement (mean value 794 +/- 149 ng/ml; p less than 0.01). These results indicate that a certain degree of myocardial necrosis occurs during value replacement that is undetectable by the usual diagnostic criteria for perioperative myocardial infarction. We conclude that the plasma level of ventricular myosin fragments is a more specific and accurate marker of perioperative myocardial necrosis than changes in the electrocardiogram or elevated creatine kinase MB levels. Therefore the detection of myosin fragments, which appear in the serum on the third day after cardiac operations, may be useful for precise comparisons of different techniques of myocardial protection.

Direct current catheter ablation of an accessory pathway in a recipient with refractory reciprocal tachycardia.

A recurrent reciprocating tachycardia developed in a 45-year-old man 2 years after heart transplantation. Electrocardiograms of both donor and recipient were normal, without patent preexcitation. An electrophysiologic study showed a left-sided Kent bundle with only retrograde conduction property. Because antiarrhythmic therapy was unsuccessful, direct current catheter ablation was performed. Since this procedure the patient remained asymptomatic without antiarrhythmic therapy.

Cardioprotective effect of intracoronary nifedipine during percutaneous transluminal coronary angioplasty. A French double-blind cross-over multicentre study.

The aim of this double-blind, placebo-controlled, cross-over study was to assess the cardioprotective effect of intracoronary nifedipine during percutaneous transluminal coronary angioplasty balloon occlusion. A balloon inflation without drug injection was initially made to ascertain that a shift of the ST segment (> or = 2 mm, 0.08 s after the J point) appeared (inclusion criterion). Two other balloon inflations were preceded by intracoronary injection of either 0.2 mg nifedipine or placebo, distal to the stenosis through the balloon catheter. The evaluation criteria were (1) time to ST segment shift, and (2) maximal amplitude of ST segment shift caused by balloon occlusion. Comparison of the data used an analysis of variance. Sixty-seven patients (mean age 54 +/- 8 years; 54 male, 13 female) were studied; 50 patients had 1-, 16 patients 2- and 1 patient 3-vessel disease. The dilated vessel was the left anterior descending coronary artery (n = 51), the right coronary artery (n = 12) and the left circumflex coronary artery (n = 4). Balloon inflation time was 100 +/- 31 s in the nifedipine group and 93 +/- 29 s in the placebo group. Five patients were excluded (procedure stopped after the first inflation in 1 and ST segment shift < 2 mm during the first inflation in 4). The time to 2-mm ST segment shift was longer in the nifedipine group than in the placebo group (62 +/- 40 s versus 51 +/- 40 s, P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult coronary aneurysms related to Kawasaki disease.

Kawasaki disease (KD) is an acute illness encountered in infancy and childhood. Cardiovascular complications of this syndrome are recognized as being part of the adult coronary artery disease population. Reported herein is the surgical treatment of multiple coronary artery aneurysms, severe stenotic lesions and thrombotic involvement of the coronary arterial tree that could be ascribed to childhood KD in two adult patients with no risk factors for atherosclerotic heart disease. Surgical management of such patients reveals safe and provides satisfactory quality of life.

Doppler echocardiographic evaluation of the Omnicarbon cardiac valve prostheses.

Comprehensive 2 D/Doppler examination of 98 patients (mean age 56), implanted between September 1984 and February 1991, with normally functioning aortic (n = 49) and mitral (n = 49) Omnicarbon valves (OC) were analyzed in order to characterize the normal hemodynamic profiles of the OC valves. The mean time from implantation was 36.4 months (range 6 to 78). The following parameters were assessed (average of 5 measurements): peak transvalvular velocity (peak V), peak instantaneous gradient (peak G), mean transvalvular gradient (mean G), effective aortic valve area (ef Va), modified aortic valve area (m Va), aortic permeability index (PI), mitral valve area (Mit Va). Doppler data were correlated to prosthetic sizes (ranging from 21-29 mm for aortic OC and from 23-31 mm for mitral OC). The study establishes normal Doppler hemodynamics for each size (especially in aortic position) of OC valves and shows excellent performance. Significant correlations between peak G, mean G, Pl, and prosthetic aortic valve size (AS) were moderate. By contrast there were strong relationships between AS and ef Va (r = 0.56, p < 0.001) or mVa (r = 0.55, p < 0.001). These data should be helpful to identify OC prosthetic dysfunction.

Enalapril in the treatment of mild-to-moderate heart failure in general medical practice: a prospective and multicentre study concerning 17,546 patients.

The objective of this study was to test the efficacy and tolerability of a precise dosage regimen of enalapril in general medical practice, in combination with conventional therapy, in patients with mild-to-moderate (NYHA classes II and III) congestive heart failure (CHF). 17,546 patients were prospectively included in this multicentre study. After three months of treatment with enalapril, 53.9% of patients were asymptomatic (NYHA Class I) and 75.1% of patients improved by at least one class in the NYHA classification. 64.6% of patients reached maintenance dosage of 20 mg/day of enalapril and mean daily dosage for all patients was 16 mg. Outcome of functional symptoms according to NYHA class was more favourable with maintenance dosages of 15 and 20 mg/day of enalapril than with maintenance dosages of 5 and 10 mg/day of enalapril. Clinical and laboratory safety was good with low rates observed of the main adverse events: cough (1.74%), hypotension (0.34%), postular hypotension (0.30%), dizziness (0.31%) and hyperkaliema (0.13%); 1.4% of patients dropped out of the study because of such events. This extensive and open study confirms, in general medical practice, the feasibility, efficacy and tolerability of a dosage regimen of enalapril, which has been previously determined in controlled studies performed in specialized medical centres, for treatment of mild-to-moderate heart failure.

[Mechanisms of restenosis after coronary angioplasty]. / Les mécanismes de la resténose après angioplastie coronaire.

Coronary restenosis is the direct result of arterial trauma caused by angioplasty and therefore affects all patients to different degrees. Fracture of the plaque extending to the media is the principal mechanism of increase of the arterial lumen after balloon angioplasty, wall stretching concerning mainly excentric lesions. Atherectomy causes pulverisation of excision of the plaque without fracture. Stents reduce the amount of debris and the torn appearances of the plaque often observed after angioplasty. Four mechanisms are involved in the induction of restenosis: neointimal hyperplasia, proportional to the amount of trauma (damage to the internal elastic layer), related to proliferation of smooth muscle cells migrating from the media to the intima nad stimulated by many growth factors: defective remodelling or chronic elastic recoil, characterised by a reduction of the arterial lumen at the angioplasty site; acute elastic recoil in the first minutes or hours after angioplasty, mainly observed in excentric lesions; thrombosis, whose role is secondary except in certain clinical situations such as unstable angina, angioplasty of saphenous vein grafts or long dissections. The classical theories of restensosis attribute a major role to initial hyperplasia but more recent experimental and clinical data, obtained largely from endocoronary ultrasonography, suggest that defective remodelling may be more important. Although endocoronary stents prevent acute and chronic elastic recoil effectively, they do not prevent restenosis which remains a complex, multifactorial phenomenon.

[Negative retrograde P wave in D1, sign of left postero-lateral Kent bundle]. / L'onde P rétrograde négative en D1, signe de faisceau de Kent postéro-latéral gauche

A negative P wave in D1 with a mean atrial vector which is horizontal or descending in the frontal plane, occurring during paroxysmal tachycardial due to reciprocal rhythm or after ventricular stimulation suggests atrial depolarisation which starts in the left auricle at some distance from the A-V node and near the pulmonary veins. In the absence of an external anterograde ventricular pre-excitation, such P waves may indicate the presence of a hidden bundle of Kent posterolaterally on the left, allowing retrograde conduction during the tachycardia by a reciprocal rhythm.

[Atrioventricular nodal tachycardia]. / Les tachycardies jonctionnelles.

The atrioventricular junction consists of the atrioventricular node and the bundle of His up to its division. All tachycardias arising in these structures or which depend on these structures for their sustenance are called "junctional". There are four main types. The first three correspond to reciprocating rhythms, nodal tachycardia, tachycardias using an accessory pathway with unidirectional retrograde conduction, and chronic reciprocating atrioventricular nodal tachycardia. All varieties of reciprocating atrioventricular nodal tachycardia have been well studied and their diagnosis is possible from the standard surface electrocardiogram from the position and morphology of the P' wave. They are accessible to radical treatment by radiofrequency ablation of the slow pathway or accessory pathway, when present. The definitive treatment of ectopic atrioventricular nodal tachycardia is not yet established and has to be considered case by case, this form of arrhythmia being rare.

[Corrected transposition of the great vessels and preexcitation syndrome (apropos of 2 cases)]. / Transposition corrigée des gros vaisseaux et syndrome de préexcitation (à propos de deux observations)

Two cases with treated transposition of the great vessels and incompetence of the left atrioventricular valve showed a type B preexcitation syndrome. In one case, this consisted of a typical W.P.W. syndrome in which the second PR interval was not shortened, but rather consisted of a delta wave and a widened QRS complex. Post mortem examination showed an abnormal connection between the bundle of His and the ventricular septum, and a low insertion of the inverted tricuspid valve. The published cases of W.P.W. syndrome in cases with treated transposition are reviewed, and the mechanism of preexciation discussed in the light of the anatomical peculiarities of the malformation and of the abnormalities which are a feature of Ebstein's syndrome.

[Treatment by endocavitary fulguration of recurrent ventricular tachycardia caused by right ventricular dysplasia]. / Traitement par électrofulguration endocavitaire d'une tachycardie ventriculaire récidivante par dysplasie ventriculaire droite.

A 27 year old man had recurrent ventricular tachycardia since the age of 16. Different antiarrhythmic drugs were used successively without success (mexiletine, amiodarone, acebutolol, propafenone, sotalol). The diagnosis of VT due to arrhythmogenic right ventricular dysplasia was suggested by the morphology of the tachycardia (left-sided delay), surface ECG appearances (right bundle branch block and potential after the QRS in right precordial leads) and the presence of delayed potentials on right ventricular endocavitary recordings. However, there were no obvious RV changes on echo or angiographic examination. The arrhythmogenic zone was localised in the postero-basal zone of the RV using three electrophysiological criteria: the recording of delayed systolic potential in sinus rhythm which overlapped into diastole during tachycardia, mapping of ventricular depolarisation during VT and results of RV "pacemapping" reproducing the appearances of the spontaneous tachycardia. VT was reproducible on stress testing (non-sustained VT at the beginning of the recovery phase) and on endocavitary stimulation. One 250 joule electric discharge between the endocavitary electrodes and a large dorsal surface electrode prevented any further attacks without antiarrhythmic therapy (follow-up: one year). Control electrophysiological investigation after 4 months showed another potentially arrhythmogenic zone which is quiescent at present.

[Right branch of the bundle of His. From morphology to its function]. / Branche droite du faisceau de His. De sa morphologie à sa fonction

A histological study of serial sections of 71 right branches of the bundle of His has enabled us to confirm the classical findings, but also lay emphasis on certain facts which are not so well known: --the presence or early collateral branches; --the concept of a septal nerve ending; --variations in its course associated with abnormalities in the relationship of the conus with the inferior part of the septum. Certain embryological and functional implications of these facts are noted.

[1st and 2d degree atrio-ventricular blocks caused by disorders of intra-auricular conduction]. / Blocs auriculo-ventriculaires du premier et deuxième degré par trouble de conduction intra-auriculaire

In three cases collected among subjects with atrial anatomical lesions (two cases of "sinus disease" with partial atrial paralysis and one traumatic lesion of the right atrium in a WPW syndrome), atrial pacing demonstrated a considerable increase of the interval between stimulus and atrial response or intra-atrial Luciani-Wenckebach periods, for slightly increased pacing rates. Conduction changes into the right atrium explain apparently paradoxical variations of the degree of pre-excitation under pacing, in the case of Wolff-Parkinson-White syndrome.

[Spontaneous blocks by intra-atrial conduction disorders of reciprocating atrioventricular rates using a Kent's bundle]. / Arrêts spontanés par trouble de conduction intra-auriculaire de rythmes réciproques auriculo-ventriculaires utilisant un faisceau de Kent.

Paroxysmal tachycardia in Type A Wolff-Parkinson-White syndrome was due to a reciprocating rhythm involving a left lateral Kent Bundle in the retrograde direction. Spontaneous interruption of the reentry resulted not from block in the normal or accessory atrioventricular pathways but from an intraatrial conduction defect: delay in conduction between the left and right atria on intraatrial reentry terminated the tachycardia.

[Electrocardiography of atrioventricular block]. / L'électrocardiogramme des blocs auriculo-ventriculaires.

A functional physiological block protects the ventricles from the risks of excessively rapid atrial rhythms. Pathological AVB is classified in three degrees according to whether the ventricular excitation is delayed, intermittent or absent. The site of AVB can be accurately determined by endocavitary electrophysiological studies but can also be estimated from the surface electrocardiographic recordings. fundamental research has questioned the sle responsibility of conduction defects in Wenckebach and paroxysmal blocks: they suggest the presence of abnormalities of excitability in pathological zones.