Biomechanical characteristics of unconditioned and conditioned latissimus dorsi muscles used for cardiocirculatory assistance.

An understanding of the biomechanical characteristics of striated skeletal muscles involved in cardiocirculatory assistance is a prerequisite to assess their efficacy and to evaluate their haemodynamic benefits. Six goats had their latissimus dorsi muscles evaluated by isometric strain gauge testing. Total tension, and both active and passive force development at different preloads were measured. The relationship between muscle impedance and starting length was also studied. Four additional muscles were submitted to isometric and isotonic strain gauge testing after 3 months of chronic electrical stimulation (Broussais Hospital protocol) with the contralateral muscle serving as a control. In isometric testing, both conditioned and unconditioned goat latissimus dorsi displayed a Frank-Starling length-tension curve, and a linear relationship between muscle impedance and starting length was found. Chronic stimulation preserved muscle mass and isometric force. Transformed muscles showed a mean 59% reduction of maximal shortening velocity; means (s.d.) residual shortening velocity at maximal work and power output was 0.17(0.07) m/s. The work and power output were both reduced 65% after stimulation, and the residual maximal power at optimal preload varied from approximately 7.7 and 9.6 W/kg. It is concluded that, following the Broussais protocol, the goat latissimus dorsi muscle retained mass and most of its isometric force-generating capacity, but lost significant work and power potential. The residual power output did not, however, preclude the possibility of a significant cardiocirculatory contribution, providing that the conditions for optimal energy transduction are adequately delineated.

Surgical technique for reinforcement cardiomyoplasty.

The current technique for reinforcement cardiomyoplasty in man is detailed. The authors emphasize the critical points that determine the perfect execution of this operation. This innovative surgical approach to heart failure is continuously evolving and, therefore, may be subject to improvement. The major principles however remain valuable.

Rhythmic and electrophysiological study after dynamic cardiomyoplasty.

To question the possible proarrhythmic effects of cardiomyoplasty (CMP), six adult goats were submitted to rhythmic and electrophysiological (EP) study 15 days before and 8 months after a posteroanterior clockwise CMP procedure using Medtronic Cardiomyostimulator (CMS) (SP1005) and electrodes (SP5528) and completion of a progressive stimulation protocol. Pre and postoperative screening included a surface ECG, 24-hour Holter monitoring, high amplitude and filtered QRS averaging, and invasive EP study performed in the postoperative period with the CMS "ON" and "OFF." One-hour Holter recording with desynchronization of the CMS was obtained. Comparison of pre and postoperative ECG and rhythmic data showed no significant difference. High amplitude QRS averaging did not evidence meeting the usual criteria of late potentials. EP values were stable in both conditions and the aggressive EP program did not show evidence of increased susceptibility to arrhythmias. Asynchronous cardiomyostimulation did not induce arrhythmias. Our data strongly suggest that provided meticulous surgical technique is used, CMP does not significantly interfere with the electrical characteristics of the normal goat heart. The procedure, despite the disturbances it provokes, does not seem to be arrhythmogenic. The function of the CMS was always appropriate, even under stressful EP conditions.

Pacemaker implantation for early sinus node dysfunction after orthotopic heart transplantation.

Among 60 patients who received OHT at our institution between November 1986 and January 1990, 4 actually needed implantation of a permanent pacemaker. Three patients with symptomatic early sinus node dysfunction were identified and were satisfactorily paced on the VVIR mode. All three showed sinus recovery within three months following implantation and had their pacemaker switched from the VVIR mode to a simple ventricular demand pacing. Interestingly, administration of beta-blocking drugs quickly reinstituted pace dependence. The patients' outcome is excellent (18 to 48 months follow-up). No difference with the global cohort of our OHT recipients was noticed, apart from an apparent high incidence of infections (3/3) with (2/3) CMV and severe rejection (3/3) during the first month postoperatively. This data suggests that sinus dysfunction may be the result of a multifactorial (rejection, CMV, ...) injury to the conduction system, and is only clinically relevant beyond a threshold level. Denervation hypersensitivity, together with correction of these factors, may account for the restoration of a sufficient reserve of conduction system, and therefore appropriate sinus node function in basal conditions.

Technique for ventricular wrapping in experimental dynamic cardiomyoplasty.

Cardiomyoplasty is a wrapping of an electrostimulated latissimus dorsi muscle flap around the heart for substitution and/or reinforcement. The surgical technique for reproducible cardiomyoplasties in the goat model is presented. The methods combine the direction of wrapping (clockwise, counter-clockwise) and the orientation of muscle fibers. A cardiomyoplasty model using right and left latissimus dorsi or left latissimus dorsi and pectoralis major as well as a split muscle technique are illustrated.

Surgical technique for cardiomyoplasty and iterative transthoracic biopsies in an experimental goat model.

Cardiomyoplasty is a new surgical procedure using transformed skeletal muscle to reinforce or substitute for the myocardium. For the purpose of studying surgical technique and investigating basic questions, we have developed a model of reinforcement cardiomyoplasty. Herein, we describe anesthetic management, surgical technique, and the technique for iterative transthoracic biopsies. This model has proven to be valuable in several long-term studies involving more than 30 goats. Preliminary data to ascertain the efficacy of the proposed technique are provided.

Influence of tension reduction and peripheral dissection on histologic, biochemical and bioenergetic profiles, and kinetics of skeletal muscle fast-to-slow transformation.

Seven goat latissimus dorsi muscles were submitted to a progressive electrostimulation program through intramuscular electrodes (Medtronic SP5528). Group 1 (n = 3) consisted of muscles stimulated in situ, and group 2 (n = 4), of muscles dissected distally and reinserted on the chest wall with a reduced tension. In group 1, complete fiber switch from type II to I occurred within 60-100 days after the beginning of stimulation, as demonstrated by myosin isoforms and lactate dehydrogenase (LDH) isozymes pattern. Respiratory chain oxidases first increased within 30-70 days after stimulation, then progressively decreased to stabilized values, higher than the basal ones. Total LDH activity showed progressive decrease to one-fifth of the initial value. Morphological analysis confirmed the structural integrity and physical reinforcement of the muscles. In group 2, respiratory chain oxidases showed initial increase followed first by a fast reduction to values less than the starting ones, and then by a slow secondary increase between day 40 and 90. LDH activity displayed a sharp decrease between day 15 and 36. Myosin as well as LDH isoforms showed progressive conversion. This kinetic study suggests a three-phase adaptative evolution of the goat latissimus dorsi submitted to increased workload (group 1): a fast increase (phase I) in oxidative capacities is followed by the development of an efficient contractile machinery (phase II), with subsequent adaptation (phase III) of the terminal chemosmotic enzymes involved in energy production.+2

[Simultaneous coronary and carotid surgery: apropos of 73 cases]. / Chirurgie coronarienne et carotidienne en simultané: à propos de 73 cas.

A series of 73 simultaneous carotid and coronary revascularizations (Group I) is presented (January 1980-December 1988). Age, sex, risk factors, severity of angina, coronarography, neurological symptoms, angiographic carotid lesions and operative outcome of these 73 patients are compared with the aspects of 3544 coronary bypass patients (Group II) and 1001 carotid endarterectomized patients (Group III) during the same period. The angina in Group I is more severe, with 22% belonging to NYHA class IV and 26% having a stenosis of the left main coronary artery, vs 14% and 13% in Group II. Seventy percent of the carotid lesions in Group I are asymptomatic vs 33% in Group III. Group I patients had more problems in the perioperative period, with 16.4% needing prolonged high-doses analeptics and 5.4% intraaortic counterpulsation balloon. Operative mortality is higher (7%) in Group I compared with Group II (2.3%) and Group III (1.7%). These results permit to define a population of polyvascular patients with concomitant coronary and carotid disease, characterized by a more diffuse atherosclerosis and a higher operative risk. Operative morbidity and mortality after combined myocardial and cerebral revascularization remains nevertheless inferior to the cumulated surgical risk of the sequential procedures (74 patients with coexistant coronary and carotid lesions operated in two sessions before 1986).

Coronary artery reoperations.

From June 1976 to June 1989, 138 previously revascularized coronary patients were reoperated upon. This represents 3.28% of all aortocoronary bypass procedures performed during the same period in our institution. Characteristics of this group, risk factors, coronarographic data, perioperative morbidity and mortality are analyzed and compared to the data of the general population undergoing bypass surgery. The mean age of individuals requiring reoperation was 59 years. The mean interval between the two operations reached 73 months (5 to 180 months). Angiographic lesions were more extensive with three-vessel disease in 65% of the reoperated patients. The mean ejection fraction was 55%. A mean of 2.1 bypass grafts per patient were inserted with 60% of cases having an internal mammary artery graft. Perioperative infarction occurred in 8.0% of the reoperations and an intraaortic balloon counterpulsation was necessary in 4.3% at the end of the procedure. Operative mortality was 5%. Symptomatic improvement was obtained in 85% of the cases. In recent years, cardiac transplantation has been performed for 11 previously bypassed patients with severely impaired ventricular function. There were no postoperative deaths. Cardiac transplantation can be considered as a more valuable alternative to repeat coronary artery bypass grafting in such cases.

[Reoperation for aortocoronary bypass]. / Les réopérations pour pontages aorto-coronaires.

Iterative aorto-coronary bypass. From 1978 to 1988, 106 previously revascularized coronary patients were reoperated. This represents 3.01% of all aorta-coronary bypass procedures performed in the same period. Characteristics of this group, risk factors, coronary anatomical data, perioperative morbidity and mortality are analyzed and compared to the data of primary revascularization. The progression of atherosclerotic disease, with an annual 2% attrition rate of bypass grafts after the first year, is evidenced by this study. The success rate of coronary reoperations approaches the results of primary bypass surgery. The causes of recurrent angina and graft failure are discussed. The mean age of individuals requiring reoperation is 58.5 years. The mean interval between the two operations reaches 66 months (5 to 168 months). Angiographic lesions are more extensive, with a three vessel disease in 75% of the reoperated patients and an ejection fraction lowered at 55%. A mean of 2.7 bypass grafts per patient is realized, with in 60% of cases an internal mammary artery graft. Perioperative infarction occurs in 10.5% of the reoperations and in 4.5%, an intraaortic counterpulsation balloon is necessary at the end of the procedure. Symptomatic improvement is obtained in 85% of cases. Operative mortality is 5.7%. These findings suggest that coronary reoperation can be accomplished with low morbidity, low mortality and a therapeutic benefit in the majority of cases. In recent years, cardiac transplantation has been considered for some patients with impaired ventricular function. This procedure is only limited by the insufficient number of donors.

Giant cell arteritis (Horton's disease) of the axillary artery--case reports.

The authors recently observed 2 elderly female patients with ischemic pain of the upper extremity as the first manifestation of giant cell arteritis. They presented with rest pain of both upper extremities and even gangrene of the thumb in 1 case. Subclavian and radial pulses were absent while peripheral pulses in the lower limbs were preserved. The angiography was so typical that the diagnosis of inflammatory arteritis was made, despite negative temporal artery biopsy. The patient with thumb gangrene was successfully operated on, the occlusive axillary lesions being bypassed by a long venous carotid humeral bypass graft. A biopsy of the axillary artery showed a granulomatous lymphoplasmocellular infiltration. A high-dose corticotherapy (24 mg daily) was begun in both cases, with dramatic improvements of general state, lowering of the erythrocyte sedimentation rate, and even reapparition of a reduced radial pulse in 1 patient. The authors discuss the incidence, symptoms, diagnosis, and treatment of systemic giant cell arteritis, with special attention to extracranial involvement. These case reports may broaden the knowledge of the diverse manifestations of giant cell arteritis and of its systemic character with widespread vascular involvement.

Artificial circus movement tachycardias: incidence, mechanisms, and prevention.

In a group of 45 patients treated with Medtronic 7000 and 7100 pulse generators for sick sinus syndrome or second or third degree atrioventricular block, an atrial synchronous mode of pacing was programmed in 34 cases and spontaneously occurring artificial circus movement tachycardias (ACMTs) were observed in nine. An analysis of conditions of occurrence, triggering mechanisms and patterns of ACMT, is presented. Various modalities of prevention are discussed. They resulted in suppression of ACMT in five patients and decrease of incidence in a sixth; the three remaining subjects were managed by definitive reprogramming in the DVI mode. Our conclusion is that correct prevention of ACMT requires the use of dual chamber pulse generators with programmable atrial refractory periods. For patients in whom a unit has already been implanted, careful observation of the triggering mechanism and pattern of ACMT may help in determining the most suitable way to prevent and suppress the arrhythmia.

Natural evolution of atrioventricular conduction in patients with sick sinus syndrome treated by atrial demand pacing. A study of 26 cases.

The authors have followed up 26 patients with sinus node disease who were treated by atrial pacing. The follow-up duration varies between 10 months and 3 years. Assessment of A.V. conduction was performed repeatedly by atrial pacing at increasing rates. Nine patients showed a progressive, sometimes early, deterioration of their A.V. conduction system; five (19%) developed second degree A.V. block of Mobitz type I for pacing rates lower than 100 beats/min. In three of them, the pace-maker had to be replaced by a dual chamber stimulator. Deterioration of A.V. conduction seems to be more frequent in subjects with antecedents of myocardial infarction (4/5) than in others (5/21: p less than 0.05). Deterioration of A.V. conduction is not uncommon among patients with sinus node dysfunction, especially after myocardial infarction. This constitutes a serious limitation to the use of atrial pacing.

[Serum activity of angiotensin converting enzyme during extracorporeal circulation in man]. / Activité sérique de l'enzyme de conversion de l'angiotensine pendant la circulation extracorporelle chez l'homme.

Serum activity of angiotensin converting enzyme (ACE) were measured during extra-corporeal circulation in five patients undergoing aorto-coronary bypass surgery. We observed a significant decrease of serum ACE levels in the absence of pulmonary circulation, suggesting that in man the lungs were the major source of circulating ACE. An effective extra-pulmonary liberation of ACE could take place during cardiopulmonary bypass. The levels of serum ACE increased with pulmonary recirculation, but preoperative levels were not reached 24 h later.

[Implantation of a cardiac pacemaker in the octogenarian]. / Implantation de stimulateur cardiaque chez l'octogénaire.

Thirteen centres, specialized in pacemakers and studying the implantation, brought together their material. Consequently, 785 patients living with a pacemaker (PM) were grouped. The average age at the time of the first implantation is 83,5 years old. The mortality of 7.5% as well as the morbidity of 16% lie very low. Nevertheless, their causes are discussed and compared to those resulting from other types of surgical pathologies on the octogenarian. It seems that the implantation of a PM, even on a person of 80 or older, is an efficient therapeutic gesture, benign and capable of normalizing the chances and quality of life on a long term basis.

[Arterial thrombosis of the lower limb in patients over 80 years of age. Belgian multicentric experience concerning 802 patients]. / Arteriële thrombose van het onderste lidmaat boven de 80 jaar. Belgische multicentrische ervaring betreffende 802 patiënten.

This report concerns a joint study of fourteen centres about the treatment of arterial occlusion of the low extremity. Eight hundred and two patients older than 80 years have been studied during a period from 1 to 27 years. The operative mortality was 25.2%. There was no significant difference in mortality between emergency cases and those patients who were operated under elective conditions. Leg amputations are followed by a significant higher mortality than more conservative surgery such as arterial by-pass, sympathectomy or embolectomy. The most frequent cause of death was from cardiopulmonar origin (57%). The postoperative morbidity of cardiac, pulmonary, urinary or infectious origin was frequent (50%). Surgical complications in the true sence of the word are quite rare and their frequency is limited to 7%. The conclusion of this study is that conservative surgery such as reascularisation or sympathectomy is, whenever possible, to be preferred over amputation not only because of their lower mortality (13 to 19%) but also since they permit better revalidation of these elderly patients.

[Reno-vascular hypertension surgery and renal: systemic renin index (author's transl)]. / Chirurgie de l'hypertension réno-vasculaire et index de rénine systémique/rénale.

Thirty-two consecutive hypertensive patients with renal artery stenoses have been operated on. Surgical procedures were aorta-renal artery grafting, renal artery endarteriectomies and resection-anastomosis. Results were analysed with respect to the radiologic type of the stenosis (i.e. arteriosclerosis (AS) or fibromuscular dysplasia (FMD) and to the value of Renal: Systemic Renin Indices (RSRI) available in 30 cases. Out of 15 FMD cases, 14 are completely cured while in 5/15 cases RSRI values were not significant. 1/15 case is a failure, RSRI was here not significant. Out of 16 AS cases, 2 died in the immediate postoperative period. Out of 14 AS survivors, 11 are completely normotensive, 2 are only improved (in 11/13 cases where RSRI were available, they were significant) and 1 is a failure (in that case RSRI was not significant). One case of arteriovenous fistula is reported; reliable RSRI determination can not be obtained in that pathology. It is the author's suggestion that every case of FMD related renovascular hypertension should be operated on irrespectively of RSRI value. Opposingly, in AS case, operative decision is dependent on prior determination of RSRI.