Gerard M. Guiraudon

Right ventricular dysplasia: a report of 24 adult cases.

Right ventricular dysplasia is characterized by an abnormality in the development of part of the right ventricular musculature. Patients with right ventricular dysplasia may present with ventricular tachycardia, supraventricular arrhythmias, right-heart failure or asymptomatic cardiomegaly. Twenty-two adult patients with right ventricular dysplasia who had recurrent ventricular tachycardia were seen during a 7-year period. The male/female ratio was 2.7: 1. The mean age at the time of hospitalization was 39 years. All but one of the patients had ventricular tachycardia of a left bundle branch block configuration. With few exceptions, the T waves were inverted over the right precordial leads. The heart was usually enlarged and the pulmonary vasculature was usually normal. In six patients who had two-dimensional echocardiograms, all showed increased right ventricular diastolic dimensions. All patients had right ventricular angiography; the diagnosis of right ventricular dysplasia was substantiated during surgery in 12 patients and at autopsy in another. Two other patients who did not have arrhythmias had right ventricular dysplasia diagnosed by right- and left-heart angiography. Our unique experience, when combined with a literature review of 34 adult cases, permits a composite clinical profile of this condition in the adult.

Mechanisms of Wave Fractionation at Boundaries of High-Frequency Excitation in the Posterior Left Atrium of the Isolated Sheep Heart During Atrial Fibrillation

Background— High-frequency fractionated electrograms recorded during atrial fibrillation (AF) in the posterior left atrium (PLA) and elsewhere are being used as target sites for catheter ablation. We tested the hypothesis that highly periodic electric waves emerging from AF sources at or near the PLA give rise to the most fractionated activity in adjacent locations. Methods and Results— Sustained AF was induced in 8 isolated sheep hearts (0.5 &mgr;mol/L acetylcholine). Endocardial videoimaging (DI-4-ANEPPS) and electric mapping of the PLA enabled spatial characterization of dominant frequencies (DFs) and a regularity index (ratio of DF to total power). Regularity index showed that fractionation was lowest within the area with the maximal DF (DFmax domain; 0.19±0.02) and highest within a band of ≈3 mm (0.16±0.02; P=0.047) at boundaries with lower-frequency domains. The numbers of spatiotemporal periodic episodes (25.9±2.3) and rotors per experiment (1.9±0.7) were also highest within the DFmax domain. Most commonly, breakthrough waves at the PLA traveled toward the rest of the atria (76.8±8.1% outward versus 23.2±8.1% inward; P<0.01). In both experiments and simulations with an atrial ionic model, fractionation at DFmax boundaries was associated with increased beat-to-beat variability of conduction velocity and directionality with wavebreak formation. Conclusions— During stable AF, the PLA harbors regular, fast, and highly organized activity; the outer limit of the DFmax domain is the area where the most propagation pattern variability and fractionated activity occur. These new concepts introduce a new perspective in the clinical use of high-frequency fractionated electrograms to localize sources of AF precisely at the PLA and elsewhere.

Encircling Endocardial Ventriculotomy: A New Surgical Treatment for Life-Threatening Ventricular Tachycardias Resistant to Medical Treatment Following Myocardial Infarction

Ventricular tachycardias occurring after myocardial infarction (MI) and resistant to medical treatment were successfully treated in 5 patients by encircling endocardial ventriculotomy. All patients had a history of MI. The delay between MI and ventricular tachycardias ranged from 1 month to 8 years. A reentrant mechanism was demonstrated by laboratory studies. Under cardiopulmonary bypass, the left ventricle was entered through the thin fribrous scar. Encircling endocardial ventriculotomy was carried out from the inside of the ventricle, through the whole thickness of the normal myocardium, and along the border of the endocardial fibrosis, which delineated the area of diseased myocardium. The ventriculotomy was placed in the free wall or in the septum or in both of these locations. It was repaired and the left ventricle was closed. Drug therapy was discontinued after operation. No ventricular tachycardias recurred during a follow-up period of 6 to 24 months. The effectiveness of encircling endocardial ventriculotomy is explained by the exclusion of the entire diseased area, especially the border zone and the septum. This technique is useful in any location of MI.

Spatial Distribution of Fibrosis Governs Fibrillation Wave Dynamics in the Posterior Left Atrium During Heart Failure

Heart failure (HF) commonly results in atrial fibrillation (AF) and fibrosis, but how the distribution of fibrosis impacts AF dynamics has not been studied. HF was induced in sheep by ventricular tachypacing (220 bpm, 6 to 7 weeks). Optical mapping (Di-4-ANEPPS, 300 frames/sec) of the posterior left atrial (PLA) endocardium was performed during sustained AF (burst pacing) in Langendorff-perfused HF (n=7, 4 &mgr;mol/L acetylcholine; n=3, no acetylcholine) and control (n=6) hearts. PLA breakthroughs were the most frequent activation pattern in both groups (72.0±4.6 and 90.2±2.7%, HF and control, respectively). However, unlike control, HF breakthroughs preferentially occurred at the PLAs periphery near the pulmonary vein ostia, and their beat-to-beat variability was greater than control (1.93±0.14 versus 1.47±0.07 changes/[beats/sec], respectively, P<0.05). On histological analysis (picrosirius red), the area of diffuse fibrosis was larger in HF (23.4±0.4%) than control (14.1±0.6%; P<0.001, n=4). Also the number and size of fibrous patches were significantly larger and their location was more peripheral in HF than control. Computer simulations using 2-dimensional human atrial models with structural and ionic remodeling as in HF demonstrated that changes in AF activation frequency and dynamics were controlled by the interaction of electrical waves with clusters of fibrotic patches of various sizes and individual pulmonary vein ostia. During AF in failing hearts, heterogeneous spatial distribution of fibrosis at the PLA governs AF dynamics and fractionation.

Demonstration of macroreentry and feasibility of operative therapy in the common type of atrial flutter.

Two patients are described who had recurrent and long-standing atrial flutter of the common type and were referred for electrophysiologic testing and surgical management. In both patients, atrial flutter could be initiated and terminated by programmed stimulation. Atrial endocardial mapping showed earliest activation during flutter at the orifice of the coronary sinus, with activity proceeding to the low atrial septum, high lateral right atrium and low right atrium, respectively. Programmed atrial extrasystoles from the high right atrium at a time when the atrial septal region was refractory advanced atrial flutter in proportion to prematurity of the extrastimulus, while maintaining the low to high activation sequence. Intraoperatively, epicardial atrial mapping revealed a large right atrial reentrant circuit beginning in the posteroseptal region and proceeding superiorly and laterally through the right atrial free wall before returning to its starting point. The narrowest part of the circuit and that showing relatively slow conduction during atrial flutter was observed in the low right atrial tissue between the tricuspid valve ring and the orifices of the inferior vena cava and proximal coronary sinus, respectively. Cryosurgical ablation around the orifice of the coronary sinus and surrounding atrial wall has prevented recurrent atrial flutter over short term follow-up in both patients, although 1 of the patients has required antiarrhythmic therapy for postoperative atrial fibrillation.

Role of the Posterior Left Atrium and Pulmonary Veins in Human Lone Atrial Fibrillation Electrophysiological and Pathological Data From Patients Undergoing Atrial Fibrillation Surgery

Background—Surgery can eliminate atrial fibrillation (AF), but data confirming the rationale for specific lesion sets are lacking. We used postoperative electrophysiological studies to test the rationale and effects of operative pulmonary venous isolation. Methods and Results—Fourteen patients undergoing surgical pulmonary venous isolation for drug-refractory lone AF were studied. Successful isolation was confirmed postoperatively in 13 of 14 patients. Spontaneous sustained AF was recorded from the isolated pulmonary venous region (PVR) in 4 and was induced by extrastimulus testing in another. The remaining atrial region (RAR) was in sinus rhythm in 13 patients and nonsustained AF in 1. Atrial extrastimulus testing and burst pacing in the RAR failed to induce sustained AF. In follow-up, 1 patient developed paroxysmal AF, and electrical continuity between the PVR and RAR was confirmed. Isolation was achieved with radiofrequency ablation with no further AF. Another patient developed typical atrial flutter that required ablation. AF has not recurred in any patient at 25.1±11.9 months (range, 6 to 56 months) after surgery. Atrial histopathology was consistent with tachycardia-induced changes. Conclusions—Total electrical isolation of the PVR controlled AF with excellent clinical outcome and appeared necessary for success. The isolated PVR can sustain spontaneous or induced AF, whereas the considerably larger RAR does not. These data provide a sound rationale for PVR in eliminating AF.

Atrial fibrillation in patients with Wolff-Parkinson-White syndrome: incidence after surgical ablation of the accessory pathway.

The effect of surgical ablation of ablation of atrioventricular accessory pathways on the incidence of atrial fibrillation in patients with Wolff-Parkinson-White syndrome was examined and the results of preoperative electrophysiologic testing were studied to determine factors predictive of outcome. Among 50 consecutive surgical cases, 19 patients were identified with a past history of at least one episode of spontaneous atrial fibrillation documented by electrocardiogram before surgery. The mean number of episodes of atrial fibrillation was 1.97/patient/year during a mean symptomatic period of 6.9 years before surgery. These patients were compared with 19 consecutive patients undergoing surgery during the same time period who had a history of only reciprocating tachycardia. Patients with atrial fibrillation had a significantly shorter antegrade accessory pathway effective refractory period (270 +/- 39 vs 330 +/- 107 msec; p less than .05) and much faster ventricular rates during induced atrial fibrillation (shortest RR interval 219 +/- 73 vs 294 +/- 60 msec, p less than .005; average RR interval 324 +/- 109 vs 405 +/- 127 msec, p less than .01). Patients with atrial fibrillation also had longer PA intervals (47 +/- 13 vs 37 +/- 7 msec; p less than .02). At preoperative electrophysiologic testing, 18 patients with atrial fibrillation had atrial fibrillation induced and 14 sustained the arrhythmia for longer than 10 min. In contrast, atrial fibrillation, although induced in 14 of 19 patients with reciprocating tachycardia, was not sustained in any. Thus electrophysiologic testing suggested that both accessory pathway properties and atrial vulnerability may predispose to atrial fibrillation.(ABSTRACT TRUNCATED AT 250 WORDS)

Sensitivity and specificity of invasive and noninvasive testing for risk of sudden death in Wolff-Parkinson-White syndrome

Invasive electrophysiologic testing and noninvasive testing were compared as methods for identifying patients with Wolff-Parkinson-White syndrome at risk for sudden death. Sixty-seven patients were studied, including nine with a history of ventricular fibrillation. Electrophysiologic testing, using the shortest interval between consecutive pre-excited beats (shortest RR interval) less than or equal to 250 ms during induced atrial fibrillation to define risk, identified seven of nine patients with previous ventricular fibrillation. The sensitivity increased to 87.5% if one patient with prior amiodarone therapy was excluded. Electrophysiologic testing had a specificity of 48.3% and a low predictive accuracy (18.9%) when using the shortest RR interval (less than or equal to 250 ms) to identify the risk for sudden death. Continuous pre-excitation after disopyramide (2 mg/kg body weight, intravenously) had a sensitivity of 71.4%, specificity of 26.1% and predictive accuracy of 12.8% for identifying patients with sudden death. Continuous pre-excitation during an exercise test identified these patients with a sensitivity of 80%, a specificity of 28.6% and a predictive accuracy of 11.8%. These noninvasive tests could also be used to predict the shortest RR interval observed during induced atrial fibrillation. Continuous pre-excitation on both tests used in combination had a sensitivity of 91.2%, a specificity of 66.7% and a predictive accuracy of 75.6% for predicting the shortest RR interval less than or equal to 250 ms. Thus, both invasive and noninvasive techniques have a good sensitivity but a low specificity for identifying patients with Wolff-Parkinson-White syndrome and sudden death.(ABSTRACT TRUNCATED AT 250 WORDS)

Aprotinin significantly decreases bleeding and transfusion requirements in patients receiving aspirin and undergoing cardiac operations

BACKGROUND Patients with heart disease are frequently maintained on a regimen of aspirin because of its ability to decrease thrombotic complications and reduce the prevalence of unstable angina and myocardial infarction. Aspirin-induced platelet acetylation also increases bleeding caused by impairment of platelet function during cardiac surgery. METHODS Between October 1990 and November 1991 this double-blind, randomized, placebo-controlled, parallel group interventional study examined the efficacy of high-dose aprotinin administration (up to 7 million KIU) to decrease blood loss and transfusion requirements in patients receiving aspirin within 48 hours of undergoing coronary bypass or valvular heart operations. Primary outcome measures in this study were total volume of blood loss (intraoperative blood loss plus postoperative chest tube drainage) and volume of transfusion during hospitalization. RESULTS Patients treated with aprotinin (n = 29) had significantly lower total blood loss (1409 +/- 232 ml versus 2765 +/- 248 ml; p = 0.0002), intraoperative blood loss (503 +/- 53 ml versus 1055 +/- 199 ml; p = 0.0001), postoperative blood loss (906 +/- 204 ml versus 1710 +/- 202 ml; p = 0.0074), and prevalence of transfusion (59% versus 88% of patients; p = 0.016) than the placebo group (n = 25). The prevalence of complications including myocardial infarction was similar in the two groups. CONCLUSIONS High-dose aprotinin significantly reduces blood loss and red blood cell transfusions in patients receiving aspirin who undergo cardiac operations.

Extended vertical transatrial septal approach to the mitral valve.

Optimal mitral valve operation requires adequate exposure without impairment of atrial physiology, namely sinus node and atrioventricular node function. We used an extended vertical transseptal atrial approach in 34 consecutive patients. The extended vertical transseptal approach combines two semicircular atrial incisions circumscribing the tricuspid and mitral annuli anteriorly and superiorly, allowing exposure of the mitral valve by deflecting the ventricular side using stay sutures. The right atrium is opened anteriorly along the atrioventricular sulcus. The atrial septum is incised vertically through the fossa ovalis. The right atriotomy is extended superiorly in the right coronary fossa between the right atrial appendage and the atrioventricular sulcus to meet the septal incision. The two joint incisions are extended onto the left atrial roof transversely. At this point, the two semicircular incisions are performed and joined, and mitral valve operation is performed. There were 18 women and 16 men. Five patients had ischemic mitral valve regurgitation, 18 had mitral valve prolapse, and 11 had rheumatic heart disease. The mitral valve was replaced in 17 patients and repaired in 17. There were no perioperative complications associated with the atriotomies, ie, no bleeding, no atrioventricular nodal dysfunction, and no sinus node dysfunction. The extended vertical transatrial septal approach provides good mitral valve exposure without inherent complications.