Detection of acute cardiac allograft rejection with high resolution electrocardiography: experimental study in rats.

BACKGROUND AND METHODS: To diagnose early acute cardiac rejection, we evaluated high-resolution electrocardiography in rats. Heterotopic heart transplantations were performed in allogeneic animals, either treated with cyclosporine or untreated, and in syngeneic animals. High-amplification electrocardiograms were recorded daily, under anesthesia, with two intra-abdominal leads. After amplification (x 5000 to 20,000), the electrocardiographic signal was acquired and analyzed with P-Clamp software. We measured the amplitude (millivolts) and duration (milliseconds) of the auriculogram (P wave) and the ventriculogram (QRS wave), the duration of auriculoventricular conduction (milliseconds; PQ interval) and the heart rate. Twenty-five grafted hearts were fully studied in recipients not treated with cyclosporine (allogeneic n = 16, syngeneic n = 9). RESULTS: In the allogeneic group, acute cardiac rejection was always accompanied by an early and progressive increase in P wave duration and PQ interval, whereas an increase in QRS duration was subsequently recorded. No significant change in P wave, PQ interval, or QRS wave duration was recorded in the syngeneic group, which showed no histologic rejection lesions. A decrease in P wave and QRS wave amplitude was recorded in both groups of animals. In the allogeneic group treated with cyclosporine (n = 21), grafted hearts were removed early (4.5 +/- 0.5 days): 10 cardiac grafts were rejected and 11 were not. An increase in P wave duration > or = 20% was associated with mild rejection in most cases. The sensitivity and specificity of this electrocardiographic sign were excellent (100%). The auricular (right and left atria) and the ventricular (right and left ventricles) tissues were evaluated histologically. In the allogeneic groups (n = 26), the histologic lesions during acute rejection were greater in the auricular myocardium than in the ventricular myocardium. Rejection in the atrial and ventricular myocardium was most often differentiated by one degree according to the Billingham classification. CONCLUSIONS: We concluded that acute cardiac rejection in rats is associated with early conduction disturbances in the atrial myocardium which can be shown by high-resolution electrocardiography.

The influence of age on valve related events with Carpentier-Edwards pericardial valves.

From July 1984 to December 1991, 641 Carpentier-Edwards pericardial valves were used in 585 consecutive patients. There were 420 aortic valve replacements, 121 mitral valve replacements, and 50 double valve replacements. Mean age was 65.5 +/- 12 years. All patients but 10 were followed up at 3 months periods with a total follow-up of 2074 patients years and a mean follow-up of 3.7 years. Patients were subdivided in 4 groups: Group I: < 50 years, Group II: 50 < age < 65, Group III: 65 < age < 75, Group IV: > 75 years. Actuarial survival rates were 100% in group I, 80 +/- 9% in group II, 68 +/- 11% in group III, and 64 +/- 13% in group IV. Valve related complications included 54 patients and valve related deaths 17. Valve related death rates were 100%, 96 +/- 3%, 95 +/- 4%, 89 +/- 10% respectively (NS). We observed 4 structural failure of the values with respective rates of freedom from valve deterioration of: 92 +/- 6%, 98 +/- 2%, 100%, 100% (NS). No leaflet tears were observed. No difference was found between the 4 age groups in terms of valve related events except for thromboembolic accidents which were more frequent in patients older than 75 years. The absence of difference at 8 years and the absence of leaflet tears indicate the superiority of the Carpentier-Edwards pericardial over previous bioprostheses and the better stress behaviour of this valve. The coming years will allow us to determine the precise place of this pericardial device, especially in young patients and in the mitral position.

[Electrophysiological properties of the transplanted heart. Clinical applications]. / Propriétés électrophysiologiques du coeur transplanté. Applications cliniques.

With the improvement in the results of cardiac transplantation, more and more cardiologists are called on to follow up cardiac transplant patients. Cardiological follow-up requires a knowledge of the electrocardiographic and electrophysiological features of the transplanted heart after surgery and the suppression of autonomic innervation. The transplanted heart ECG is characterised by the presence of 2 P waves of different morphology and frequency (from the native and transplanted atria), an acceleration of the sinus rhythm, clockwise rotation of the longitudinal axis, right bundle branch block and ST-T segment changes. The increase in heart rate during exercise is catecholamine-dependent, more progressive and less important than in normal subjects, as is the deceleration of the cardiac rhythm when exercise is stopped. The observation of early sinus node dysfunction is not rare (6.6%) and though usually asymptomatic and transient, implantation of a pacemaker is commonly proposed with different modes of stimulation (VVI, VVIR, AAIR, AAT). The authors have observed changes in the electrophysiological properties of experimental transplanted hearts during acute rejection. The most important of these were in the conduction of the activation within the atrium and in the atrioventricular node, and a reduction in the amplitude of the ventricular potential. The recording of these changes in humans by a non-invasive method could help early diagnosis of acute rejection and limit the number of endomyocardial biopsies. Of the non-invasive techniques under assessment, signal-averaged electrocardiography (temporal and/or frequency analysis) seems to be the most promising.

[A rare cause of pure isolated chronic aortic insufficiency: congenital quadricuspid aortic valve. Apropos of 2 cases]. / Une cause rare d'insuffisance aortique pure, isolée et chronique: la quadricuspidie aortique congénitale. A propos de deux cas.

The authors report two new cases of congenital quadricuspid aortic valve complicated by pure, severe, chronic, aortic regurgitation. This abnormality was diagnosed fortuitously at transoesophageal echocardiography in one case and at aortography in the other, and confirmed at surgery. This congenital abnormality was associated with superior displacement of the left coronary ostium.

[Surgery of valve replacement with pericardial prosthesis]. / Chirurgie de remplacement valvulaire par prothèse péricardique.

The ideal artificial heart valve still does not exist among the various cardiac valves available to the clinician. Morbidity and mortality are directly related to the valve itself. Despite the promising hemodynamic results obtained in the 70s with pericardial prosthesis, these valves were progressively abandoned due to their poor long-term resistance. Based on an analysis of the causes of failures, modifications were made in the manufacturing method and current results with pericardial valves has greatly improved, inciting new interest in their clinical use. Today, the pericardium is recognized as a valid substitution material for bioprostheses. Results of long-term series should confirm current studies. Research is under way to determine how to improve pericardium longevity since tissue deterioration remains the limiting factor.

Electrocardiographic and electrophysiologic properties of cardiac allografts.

The increasing number of heart transplant patients requires that physicians be able to recognize the electrocardiographic (ECG) and electrophysiologic properties of cardiac allografts. Cardiac allografts are characterized by modifications of resting ECGs and frequent arrhythmias in the postoperative period, and the loss of autonomic nervous control illustrated by permanent tachycardia and loss of heart rate variability during 24-hour ambulatory ECG recording. Some clinical and experimental observations suggest a mid-term reinnervation of the cardiac allograft, but this requires histologic confirmation. The electrophysiologic characteristics of the denervated myocardium are similar to those of the innervated myocardium at rest. However, supersensitivity to circulating catecholamines has been observed in cardiac allografts as in experimentally denervated hearts, which is responsible for a progressive increase in heart rate during exercise and a slow decrease during recovery. Supersensitivity of the denervated heart to acetylcholine may explain the high prevalence of donor sinus dysfunction due to impairment of its automaticity. More often, the sinus node dysfunction is transient and can be treated with an adenosine antagonist, such as theophylline, before permanent implantation of a pacemaker. In the case of pacemaker implantation, synchronization of the donor atria with the recipient atria is desirable, and an endocardial lead implantation is preferred. Several electrophysiologic changes have been observed during acute cardiac allograft rejection. From experimental studies, the most important of these are the disturbance of conduction in the atria and the atrioventricular node and a decrease in the amplitude of the ventricular potential. Initial studies on isolated myocytes show profound changes in membrane conductance during experimental cardiac rejection. The development of new noninvasive detection methods of cardiac allograft rejection, such as intramyocardial voltage electrogram monitoring and high-resolution ECG, could help early diagnosis.