Biomedical subjects

C M Guiraudon

Publications and source records attributed to C M Guiraudon.

13 recordsLinked to original sources

PubMed1996

Atrial flutter: lessons from surgical interventions (musing on atrial flutter mechanism).

We report our experience with seven patients who underwent direct surgical ablation of problematic common flutter. Intraoperative mapping was obtained in four patients. Surgical techniques varied over time. A circular incision of the right atrium was performed in the first patient. Two patients had epicardial cryoablation of the isthmus between the inferior vena cava and the tricuspid valve annulus. Four patients had extensive endocardial cryoablation of the isthmus. There were no immediate postoperative complications. One patient had atrial fibrillation 2 months postoperatively and underwent a corridor operation 1 year later. The other six patients are free of arrhythmias without antiarrhythmic drugs. Surgical ablation confirmed that the common form of atrial flutter is associated with a right atrial macroreentrant circuit. One of our intraoperative endocardial maps suggested that variant reentrant circuits can be associated with variant forms of flutter.

Adult↗

PubMed1996

Surgery for supraventricular tachycardia.

1995 is the fifth anniversary of the advent of catheter ablation for the treatment of supraventricular tachycardia. Surgery has established the principles of the interventional approaches: 1) identification of the mechanism; 2) localization of the site of the mechanism; 3) identification of the anatomical arrhythmogenic substrate and its localization using preoperative and intraoperative electrophysiological cardiac mapping; 4) ablation of the arrhythmogenic substrate using "surgical" dissection or excision or various forms of energy to neutralize the substrate: cryoablation, laser, etc. Surgical approaches also established the EP interventions as the first line of therapy because they are curative. Currently, surgery for supraventricular tachycardia is essentially confined to atrial fibrillation, and after attempted catheter ablation for the Wolff-Parkinson-White syndrome. Atrial fibrillation is a complex arrhythmia, commonly associated with structural heart disease. To understand atrial fibrillation, a number of premises should be reviewed: atrial functional anatomy, atrial pathology, atrial fibrillation mechanism (s) and clinical presentation. The role of atrial fibrillation in terms of symptoms, morbidity and mortality is not clear because it is difficult to determine if atrial fibrillation is a symptom, a marker, an autonomous disease albeit it is in most cases an aggravating factor. Surgical rationales for atrial fibrillation are based on three concepts: exclusion, fragmentation and channelling. The Corridor operation was the first used direct surgical approach. The Maze operation and other techniques (fragmentation, spiral) have been reported. All surgical techniques have been reported with good results in terms of sinus node function and exercise tolerance, and to various degrees, in terms of atrial contraction. Currently, there is a trend to combine direct atrial fibrillation surgery with surgery for mitral valve albeit beneficial effects are not documented.

Atrial Fibrillation↗

PubMed1995

Chronic rapid atrial pacing. Structural, functional, and electrophysiological characteristics of a new model of sustained atrial fibrillation.

BACKGROUND: Despite the clinical importance of atrial fibrillation (AF), the development of chronic nonvalvular AF models has been difficult. Animal models of sustained AF have been developed primarily in the short-term setting. Recently, models of chronic ventricular myopathy and fibrillation have been developed after several weeks of continuous rapid ventricular pacing. We hypothesized that chronic rapid atrial pacing would lead to atrial myopathy, yielding a reproducible model of sustained AF. METHODS AND RESULTS: Twenty-two halothane-anesthetized mongrel dogs underwent insertion of a transvenous lead at the right atrial appendage that was continuously paced at 400 beats per minute for 6 weeks. Two-dimensional echocardiography was performed in 11 dogs to assess the effects of rapid atrial pacing on atrial size. Atrial vulnerability was defined as the ability to induce sustained repetitive atrial responses during programmed electrical stimulation and was assessed by extrastimulus and burst-pacing techniques. Effective refractory period (ERP) was measured at two endocardial sites in the right atrium. Sustained AF was defined as AF > or = 15 minutes. In animals with sustained AF, 10 quadripolar epicardial electrodes were surgically attached to the right and left atria. The local atrial fibrillatory cycle length (AFCL) was measured in a 20-second window, and the mean AFCL was measured at each site. Marked biatrial enlargement was documented; after 6 weeks of continuous rapid atrial pacing, the left atrium was 7.8 +/- 1 cm2 at baseline versus 11.3 +/- 1 cm2 after pacing, and the right atrium was 4.3 +/- 0.7 cm2 at baseline versus 7.2 +/- 1.3 cm2 after pacing. An increase in atrial area of at least 40% was necessary to induce sustained AF and was strongly correlated with the inducibility of AF (r = .87). Electron microscopy of atrial tissue demonstrated structural changes that were characterized by an increase in mitochondrial size and number and by disruption of the sarcoplasmic reticulum. After 6 weeks of continuous rapid atrial pacing, sustained AF was induced in 18 dogs (82%) and nonsustained AF was induced in 2 dogs (9%). AF occurred spontaneously in 4 dogs (18%). Right atrial ERP, measured at cycle lengths of 400 and 300 milliseconds at baseline, was significantly shortened after pacing, from 150 +/- 8 to 127 +/- 10 milliseconds and from 147 +/- 11 to 123 +/- 12 milliseconds, respectively (P < .001). This finding was highly predictive of inducibility of AF (90%). Increased atrial area (40%) and ERP shortening were highly predictive for the induction of sustained AF (88%). Local epicardial ERP correlated well with local AFCL (R2 = .93). Mean AFCL was significantly shorter in the left atrium (81 +/- 8 milliseconds) compared with the right atrium 94 +/- 9 milliseconds (P < .05). An area in the posterior left atrium was consistently found to have a shorter AFCL (74 +/- 5 milliseconds). Cryoablation of this area was attempted in 11 dogs. In 9 dogs (82%; mean, 9.0 +/- 4.0; range, 5 to 14), AF was terminated and no longer induced after serial cryoablation. CONCLUSIONS: Sustained AF was readily inducible in most dogs (82%) after rapid atrial pacing. This model was consistently associated with biatrial myopathy and marked changes in atrial vulnerability. An area in the posterior left atrium was uniformly shown to have the shortest AFCL. The results of restoration of sinus rhythm and prevention of inducibility of AF after cryoablation of this area of the left atrium suggest that this area may be critical in the maintenance of AF in this model.

Animals↗

PubMed1995

Latissimus dorsi dynamic cardiomyoplasty: role of combined ICD implantation.

Latissimus dorsi cardiomyoplasty is a promising surgical therapy in some patients with congestive heart failure. Although the mortality in heart failure patients is attributable primarily to heart failure and ventricular arrhythmias, the mechanism of death after cardiomyoplasty is not well characterized. We describe the clinical course of a patient undergoing cardiomyoplasty and discuss the role of combined use with an implantable cardioverter defibrillator. A 39-year-old man with congestive heart failure due to a massive anterior wall myocardial infarction was evaluated for latissimus dorsi cardiomyoplasty. The patient was in NYHA Functional Class III due to heart failure. He did not have any significant exertional or rest angina. During a Naughton stress test, the patient could exercise for 10 minutes, achieving 4 METS. Pulmonary function study showed a peak V O2 of 22.1 mL/min per kg. Radionuclide angiography demonstrated that the anterior wall was akinetic with a left ventricular ejection fraction of 22%. Cardiac hemodynamic studies suggested moderate pulmonary hypertension, elevated wedge pressure, and suboptimal response to exercise. A Holter recording showed frequent ventricular extrasystoles. Cardiomyoplasty was preferred to heart transplantation because the patient did not have end-stage heart failure. Postoperatively, the patient required low doses of dopamine. He developed recurrent, sustained, and hemodynamically significant episodes of ventricular tachycardia. He was treated with a combination of amiodarone and procainamide. He died 2 days postoperatively with ventricular fibrillation. Ventricular arrhythmias are a major cause of death in patients with heart failure. Latissimus dorsi cardiomyoplasty appears to be a promising but unproven therapy in such patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Encircling endocardial cryoablation for ventricular tachycardia after myocardial infarction: experience with 33 patients.

Encircling endocardial cryoablation, consisting of circumferential cryoablation of the infarct scar, can be curative in selected patients with ventricular tachycardia (VT). We describe our experience with and long-term outcome in 33 patients undergoing this procedure. The interval between myocardial infarction and the onset of tachycardia varied from 2 weeks to 22 years (mean 38 +/- 63 months and median 3 months). All patients had a left ventricular aneurysm (anterior in 20, posterior in 12, and lateral in 1) and significant coronary artery disease. Fourteen patients had clinical evidence of heart failure preoperatively. Twenty-eight patients had sustained monomorphic VT (incessant in 3); 3 had polymorphic or nonsustained tachycardia; 2 had primary ventricular fibrillation; and 1 had associated Wolff-Parkinson-White syndrome. Surgery was undertaken after failed drug therapy and consideration of left ventricular anatomy and function. At surgery, 32 patients had encircling endocardial cryoablation, and 1 patient had partial right ventricular free-wall disconnection (right ventricular infarct). Thirteen patients underwent concomitant coronary artery bypass grafting. An implantable cardioverter defibrillator (ICD) was implanted in 2 patients and prophylactic ICD patches in 1. One patient died postoperatively; 3 had recurrent VT perioperatively; 1 was treated with amiodarone; and 2 had ICD implantation. During long-term follow-up (mean 5 years), all patients who were free of tachycardia at discharge remained alive and free of arrhythmias or syncope. The patient receiving amiodarone sustained a cardiac arrest subsequently and received an ICD implant. One patient with an ICD continued to receive appropriate shocks frequently and died 2 years after surgery. Nine patients had congestive heart failure postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗

PubMed1994

Operation for the Wolff-Parkinson-White syndrome in the catheter ablation era.

Catheter ablation has greatly altered surgical referral patterns for the Wolff-Parkinson-White syndrome. We describe 51 patients (aged 9 to 63 years; 35 male, 16 female) referred for operation from our institution and elsewhere between August 1990 and August 1993, coincident with the inception of our ablation program. During the same period, 375 patients with problematic Wolff-Parkinson-White syndrome had ablation procedures. Operation was the initial therapy in 26 patients, due to physician preference in 23 and the need for a concomitant cardiac operation in 3. Operation was related to ablation failure in 22 patients and was urgent in 3 patients. Previous ablation was not associated with added surgical difficulties, and all pathways were ablated intraoperatively on the first attempt using the epicardial approach. Visible epicardial lesions were observed in 8 patients at the site of the accessory pathway. In 2 patients, the lesions were remote to the atrioventricular ring. There was a striking significant increase in proportion of right free wall pathways after attempted ablation (27% versus 8%) as compared with the preablation era. We conclude that previous attempted ablation does not impair efficacy and safety of operative therapy. Operation remains a useful alternative for ablation failure and as a back-up for acute complications.

Adolescent↗

PubMed1994

Intraoperative mapping is not necessary for VT surgery.

Surgical ablation of ventricular tachycardia is generally guided by the results of pre- and intraoperative cardiac mapping. However, in certain situations intraoperative cardiac mapping may not be possible and, therefore, surgery has to be based on information obtained preoperatively. This raises the question whether intraoperative mapping is necessary for the success of this approach. We describe our experience with encircling endocardial cryoablation for ischemic VT and examine the contribution of intraoperative mapping for this procedure. Thirty-three patients with inducible VT refractory to medical therapy and a well defined anatomic scar were considered for surgery. All patients underwent baseline electrophysiology study and intraoperative mapping was attempted during normothermic cardiopulmonary bypass. In 14 patients, VT was inducible intraoperatively (Group 1) and surgical ablation was guided by this information, whereas in 19 patients, VT could not be mapped for various reasons (Group 2). Reasons for failure to obtain intraoperative map included noninducibility (3), nonsustained VT (8), polymorphic VT (4), VF (3), and incessant VT with hemodynamic collapse and cardiac arrest (1). The two groups did not differ with respect to age, location of myocardial infarction, or preoperative left ventricular ejection fraction. The operative procedures were similar in the two groups with respect to aortic cross clamp time, cardiopulmonary bypass time, number of cryoablation lesions, concomitant revascularization, aneurysmectomy, and ICD implantation. Encircling endocardial cryoablation was performed in 32 patients and one patient underwent partial right ventricular free wall disconnection (RV infarct). Thirteen patients underwent concomitant coronary artery bypass grafting (5 in Group 1 and 8 in group 2). One patient had prophylactic ICD patches (Group 1).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Pacing, Artificial↗

PubMed1992

A permanent transvenous lead system for an implantable pacemaker cardioverter-defibrillator. Nonthoracotomy approach to implantation.

A transvenous lead system for implantable defibrillators would obviate a surgical thoracotomy and reduce the morbidity and mortality associated with implantation. We evaluated the clinical performance of a new nonthoracotomy lead system that included a defibrillation lead in the coronary sinus. At the time of defibrillator implantation, transvenous defibrillation leads were inserted percutaneously through the left subclavian vein into the right ventricular apex (RVA), superior vena cava (SVC), and distal coronary sinus (CS) under fluoroscopic guidance. A subcutaneous patch electrode (SQ) was also available if required. The first single- or dual-pathway electrode configuration that successfully terminated three of four ventricular fibrillation episodes using 18 J or less was implanted. Eleven men and three women aged 39-77 years (60.0 +/- 10.1 years) with left ventricular ejection fraction ranging from 16% to 63% (33.4 +/- 13.1%) were evaluated. Nine presented with ventricular tachycardia, three had ventricular fibrillation, and two had both. A totally transvenous lead system (RVA/CS/SVC) was implanted in seven patients (50%) with a mean defibrillation threshold of 15.6 +/- 2.9 J (10-18 J). Four patients received a partial transvenous lead system (RVA/CS/SQ). An effective nonthoracotomy lead system was not found in three patients; they received epicardial electrodes. After cumulative follow-up of 73 patient-months, nine patients remain alive and free of problems related to the implanted nonthoracotomy leads. One patient died of respiratory failure 3 months after defibrillator implant, and the leads from another patient were removed at 9 months because of bacterial infection. A transvenous lead system that includes a defibrillation lead in the coronary sinus is a safe, reliable, and, at least in the short term, effective nonthoracotomy approach for automatic defibrillator implantation.

Adult↗

PubMed1990

Anatomically guided surgery to the AV node. AV nodal skeletonization: experience in 46 patients with AV nodal reentrant tachycardia.

We report our combined experience with operative therapy for atrioventricular nodal tachycardia using an anatomically guided procedure. The operative rationale was to dissect the AV node with the intent of modifying perinodal tissues (skeletonization). The anterior septal and posterior septal regions were initially approached epicardially to facilitate endocardial dissection. Under normothermic cardiopulmonary bypass, the right atrial septum was mobilized and the intermediate AV node was exposed anterior to the tendon of Todaro. Ablation of concomitant accessory pathways was done prior to AV nodal skeletonization. Forty-six patients aged 9-71 years (mean 36) were operated upon. Five patients had accessory pathways in addition to AV nodal reentry. At electro-physiological study prior to discharge, no patient had an AV block although anterograde and retrograde Wenckebach cycle lengths were significantly prolonged. Ten patients had a retrograde AV block. The 46 patients were free of arrhythmia and not taking antiarrhythmic medication after a follow-up of 1-45 months (mean 17). Three patients had a recurrence of the tachycardia 10 days, 2 months and 7 months post-operatively, respectively. All patients had a subsequently successful reoperation.

Adolescent↗

PubMed1989

Mitral valve function after cryoablation of the posterior papillary muscle in the dog.

Extensive cryoablation of an arrhythmogenic left ventricular posterior papillary muscle associated with ventricular arrhythmias may affect mitral valve function. We studied the long-term effects of extensive cryoablation of the posterior papillary muscle and its ventricular attachment in 10 dogs. The dogs had hemodynamic, electrophysiological, and angiographic testing 1 month after operation. Seven dogs were then killed, and the hearts were examined at that time. Three dogs had repeat assessments 2 and 3 months after operation before they were killed. At 1 month, left ventricular angiography showed normal mitral valve function in all dogs. Pathological examination revealed that the posterior papillary muscle and its left ventricular attachment were replaced by a discrete dense, fibrous scar. The fibrous process involved the mitral valve in 2 dogs. At 3 months, pathological examination showed a marked fibrous scar with chondroid metaplasia and fibrous involvement of the mitral valve chordae and posterior leaflet in all 3 dogs. We conclude that extensive cryoablation of the posterior papillary muscle is not associated with long-term mitral valve dysfunction, and may be the best surgical technique to ablate an arrhythmogenic papillary muscle.

Animals↗

PubMed1989

Surgical therapy for arrhythmogenic right ventricular adiposis.

Arrhythmogenic right ventricular adiposis, formerly dysplasia, was identified when the first patients underwent map-guided surgery for treatment of their ventricular tachycardia. We report our experience with 12 patients operated on using a conservative approach between 1973 and 1981 (Paris). Subsequently, we used a more comprehensive approach in five patients (London, Canada); the right ventricular free wall disconnection was used to confine all potential right ventricular tachycardias within the excluded right ventricular wall.

Adipose Tissue↗

PubMed1989

Histological diagnosis of right ventricular dysplasia: a role for electron microscopy?

Right ventricular dysplasia is a rare cardiomyopathy predominantly involving the right ventricle. We report eight cases studied with light and electron microscopy. By light microscopy, we found the typical replacement of myocardium with mature adipose tissue where only scattered degenerated myocytes wrapped in thin fibrous sheets are seen. Electron microscopy shows abnormal intercalated discs in both the right and left ventricles: intercalated discs are attenuated and flattened with decreased Z band material (desmin). These changes, not previously reported, may be useful for diagnosing ARVD.

Adipose Tissue↗

PubMed1988

The coronary sinus diverticulum: a pathologic entity associated with the Wolff-Parkinson-White syndrome.

Of 65 patients with posterior septal accessory pathways, 6 were found intraoperatively to have a previously unrecognized pathologic entity: a coronary sinus (CS) diverticulum in the posterior septal region. The CS diverticulum is a venous pouch within the left ventricular wall, with a neck opening into the CS. The pouch, 2 to 5 cm in diameter, has a deep wall corresponding to the left ventricular wall, with venous channel openings and a thin superficial wall made of myocardium. The CS diverticulum neck is 5 to 10-mm wide, opens into the CS and is proximal to the midcardiac vein. Using an epicardial approach during normothermic bypass, the neck of the CS diverticulum was identified, separated from the left ventricle and then closed. Accessory pathway conduction disappeared only after separation of the CS diverticulum neck. The accessory pathway is intimately related to the diverticulum. The latter is a bridge between the left ventricle and the right or left atrium. The accessory pathways associated with CS diverticula had short anterograde refractory periods and were associated with potentially malignant arrhythmias. An epicardial operative approach with division of the neck of the diverticulum is recommended when surgery is indicated.

Adult↗