Surgical treatment for ectopic atrial tachycardia

Surgical Treatment for Ectopic Atrial Tachycardia Angelo Graffigna, MD, Mario Vigano, MD, Francesco Pagani, MD, and Giorgio Salerno, MD Divisions of Cardiac Surgery and Cardiology, IRCCS Policlinico "S. Matteo," University of Pavia, Pavia, Italy

Atrial tachycardia is an infrequent but potentially dangerous arrhythmia which often determines cardiac enlargement. Surgical ablation of the arrhythmia is effective and safe, provided a careful atrial mapping is performed and the surgical technique is tailored to the individual focus location. Eight patients underwent surgical ablation of ectopic atrial tachycardia between 1977 and 1990. Different techniques were adopted for each patient according to the anatomical location of the focus and possibly associated arrhythmias. Whenever possi-

ble, a closed heart procedure was chosen. In 1 patient a double focal origin was found and treated by separate procedures. In 1 patient with ostium secundum atrial septa1 defect and atrial flutter, surgical isolation of the right appendage and the ectopic focus was performed. In all patients ectopic atrial tachycardia was ablated with maintenance of the sinoatrial and atrioventricular nodal function as well as internodal conduction. In follow-up up to December 1991, no recurrency was recorded. (Ann Thorac Surg 1992;54:33843)

E

Abnormal automaticity is suggested by the impossibility of initiating or terminating the tachycardia by means of atrial electrical stimulation; resetting of the tachycardia may be achieved by means of atrial premature extrastimuli close to the arrhythmogenic focus. Maneuvers or drugs affecting AV node conduction may reduce ventricular rate without affecting the atrial automatic activity. Ectopic atrial tachycardia is frequently refractory to any form of medical treatment [l,2, 6, 131. Sporadic reports have been published referring to the effective use of drugs suppressing atrial automaticity such as P-blocking or calcium-channel-blocking agents, flecainide, ethmozin, and amiodarone for the control of EAT. Typically, though, medical treatment is ineffective in preventing the tachycardia, and patients may require further intervention due to the development of syncope or signs of congestive heart failure. Nonmedical treatment of the syndrome was based in the past on surgical or catheter interruption of AV conduction with consequent pacemaker implantation. Direct surgical treatment of EAT by means of focus isolation was performed by Coumel and associates [15]. Other techniques have been described for the ablation of the arrhythmogenic focus: resection, electrocoagulation, and cryoablation. Catheter ablation of the focus has been achieved by some authors [2] in patients with right-sided foci, whereas radiofrequency modulation of the AV conduction has been recently developed to blunt ventricular response rate at high atrial tachycardia rates. This article reports our experience in the surgical treatment of ectopic atrial tachycardia.

ctopic atrial tachycardia (EAT) is a particular supraventricular tachycardia due to abnormally automatic activity within the aspecific atrial myocardium. Onset of the arrhythmia may be in any period of life, but it is more common in infants and children [14], being described also before birth [2, 51. Although an association with atrial neoplasms has been described, patients with EAT typically show no evidence of any defined organic heart disease. A few patients have a positive familial history for EAT [6]. The tachycardia may be paroxysmal or chronic; attacks may last from minutes to hours, being spontaneous or triggered by particular maneuvers. Symptoms may include palpitations, shortness of breath, and dizziness, but patients may experience cardiac arrest due to hemodynamic derangement during EAT with extremely rapid atrioventricular (AV) conduction. Signs of congestive heart failure may be evident only during attack, but long-standing tachycardia may cause progressive reduction of ejection fraction and compensatory left ventricular dilatation. The mechanism of this process may be chronic depletion of myocardial highenergy phosphates, which has been found in experimental long-standing tachycardia [7-121. Electrocardiographical patterns of the condition are a narrow QRS tachycardia and distinct P waves with possibly altered P wave morphology and axis, and a ratedependent second- or third-degree AV block. Tachycardia begins with P wave of identical morphology to the following ones; a peculiar increase of the atrial rate after the onset of ("warming-up phenomenon") and a variability of P-P' interval during the paroxysms has been attributed to a possible influence of autonomic tone on the arrhythmogenic focus. Accepted for publication Jan 24, 1992 Address reprint requests to Dr Graffigna, Divisione di Cardiochirurgia, IRCCS Policlinico S. Matteo, Piazzale Golgi 4, 27100 Pavia, Italy.

0 1992 by The Society of Thoracic Surgeons

Material and Methods

Patient Group From December 1977 to November 1990, 8 patients were referred to our center for surgical ablation of ectopic atrial tachycardia. Preoperatively, all patients underwent a thorough cardiac evaluation, with two-dimensional and 0003-4975/92/$5.00

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Table 1. Patient Characteristics Patient No.

Sex

Age (y)

Indication for Operation

LVEDVI (mL/m2) LVEF

M M F F F F F M

19 20 17 49 46 43 34 32

CHF, cardiomegaly CHF, cardiomegaly Syncope Exertional dyspnea Previous cardiac arrest Syncope ASD, atrial flutter, EAT Exertional dyspnea

250 172

0.32 0.52

147

0.38

ASD = atrial septa1 defect; EAT = CHF = congestive heart failure; ectopic atrial tachycardia; LVEDVI = left ventricular end-diastolic LVEF = left ventricular ejection fraction. volume index;

Doppler ultrasonography; cardiac catheterization was also used in patients with evident cardiomegaly. Details on patients' preoperative status are presented in Table 1. At operation median sternotomy was performed and epicardial electrodes were placed on the right and left atrial appendages. Atrial mapping was performed during tachycardia, if present, by means of hand-held bipolar electrodes; focus location was identified on the basis of the earliest activation recorded during tachycardia compared with the reference P wave. If tachycardia was not present, premature atrial stimulation was performed and atropine or isoproterenol was administered to enhance the focus automaticity. Occasionally, automatic mapping of the zone of earliest activity was performed by means of a plaque of 12 bipolar electrodes (Bard equipment) to further define the focus location. All patients were followed up with a complete electrophysiologic study at 3 months and with regular clinical and electrocardiographic evaluations.

\

Fig 1. Electrical isolation of the left atrium is obtained by continuing a left paraseptal atriotomy along the roof of the left atrium, ending anteriorly a few millimeters from the left fibrous trigone. Posteriorly the incision is conducted tozuard the posteromedial mitral cornmissure, as far as a feu1 millimeters from the annulus. Cryoablations are added at the edges of this incision to ensure electrical isolation of the atrium. (CS = coronary sinus; LAA = left atrial appendage; MV = mitral valve.)

cardia, and therefore a round patch of atrial tissue 2 cm in diameter was removed.

Surgical details are displayed in Table 2.

PATIENT 2. The focus was located on the posterior left atrium close to the ostium of the right superior pulmonary vein. After an attempt at epicardial cryoablation failed, cardiopulmonary bypass was commenced and surgical isolation of the left atrium was performed (Fig 1).

The focus was found on the right atrial free wall close to the inferior vena cavalright atrium junction. Application of a clamp immediately interrupted the tachy-

PATIENT 3. The earliest activation was on the medial wall of the right appendage. Four cryolesions were placed on the medial wall of the right appendage at the edge of the

Surgical Details PATIENT 1 .

Table 2. Surgical and Follow-iia Details Patient No.

Date of Operation

1 2

16112/77 2/12/86 15/1/88 29/2/88 15/9/89 11/12/89

7

10/4/90 7/11/90

8 IVC

=

inferior vena cava;

LA

=

Focus Location

Technique

Result

Follow-up (mo)

IVCIRA junction RSPV ostium Right appendage Fossa ovalis Right appendage High atrial septum Posterior left atrium Posterior left atrium Fossa ovalis

Excision LA isolation Cryoablation Cryoablation Excision, pericardial patch Excision, Gore-Tex patch LA isolation Extended RA isolation Cryoablation

SR SR SR SR SR SR

164 60 47 46 27 24

SR SR

20 14

left atrium;

RA

=

right atrium;

RSPV

=

right superior pulmonary vein;

SR

=

sinus rhythm

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atrial septum. Cardiopulmonary bypass was established, and through a right atriotomy and with a beating heart five more cryolesions were placed on the right side of the high interatrial septum (Fig 2 ) . PATIENT 4. The focus was on the medial wall of the right appendage and on the contiguous roof of the atrial septum. Under cardiopulmonary bypass with bicaval cannulation, the right appendage was opened and amputated, and three cryolesions were placed anterior to the fossa ovalis.

Fig 3 . Combined isolation of the right appendage and of an ectopic focus close to the ostium of the right inferior pulmonary vein (asterisk). Under cardiopulmonary bypass with bicaval cannulation a right atriotomy was performed, starting 2 cm from the superior cavoatrial junction. The incision was extended anteriorly toward the right coronary fossa as far as a few millimeters from the tricuspid annulus. Posteriorly, the incision was conducted through the high atrial septum and along the ostium of the right inferior pulmonary vein toward the mitral valve annulus, a few millimeters apurt from this. From the caudal edge of the atrial septal defect (ASD) another incision was carried toward the ostium of the coronaiy sinus (CS) and toward the posterornedial commissure. Cryolesions were applied at the edges of the three incisions (circles) to ensure electrophysiologic isolation of the atrial segment thus encompassed. (AVN = site of the atrioventricular node; LAA = left atrial appendage.)

A

PATIENT 5. The earliest atrial activation was between the edge of the right appendage and the tricuspid annulus. Both ventricles showed a lipomatous infiltration of the basal segments. Under cardiopulmonary bypass a resection of the area was performed and a pericardial patch was positioned.

There was one focus on the high atrial septum and one on the posterior wall of the left atrium. Under cardiopulmonary bypass and with a beating heart, right atriotomy was performed and further mapping was conducted on the interatrial septum: the first focus was located on the posterior limb of the fossa ovalis. Cardioplegia was administered and the interatrial septum was resected and replaced by a Gore-Tex patch. Left atrial isolation was then performed to ablate the second focus. PATIENT 6.

Patient 7 was a 34-year-old woman with ostium secundum atrial septal defect and left to right shunt. The patient suffered from recurrent atrial flutter and ectopic atrial tachycardia. Intraoperative electrophysiologic study flutter and located the EAT focus On type I the Posterior left atrial wall, lust below the ostium Of the right inferior pulmonary vein. Right atrial isolation and focus isolation were then performed (Fig 3). PATIENT 7.

B

Fig 2 . Epicardial cryoapplications are placed on the medial aspect of the right appendage ( A ) . Serial cryoapplications are placed anterior to the fossa ovule under cardiopulmonary bypass and with a beating heart (B).

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A

Fig 4. (Patient 2.) ( A ) Preoperative surface electrocardiogram showing altered morphology of P wave during tachycardia interrupted by single sinus beats (top) and Holter monitoring pattern showing a heart rate of 130 beatslmin with paroxysms of faster ventricular response (bottom). ( B ) Postoperative esophageal (E) and surface electrocardiogram showing sinus rhythm and ongoing fast ectopic activity in the isolated left atrium (arrows). PATIENT 8 . The earliest atrial activation was on the high atrial septum, but atrial septal mapping defined the focus between the fossa ovale and the tendon of Todaro. Due to the proximity of the atrioventricular node cryolesions were placed under electrocardiographical monitoring of AV conduction.

Results Ablation of the tachycardia was obtained in every patient. In all but 1 patient sinus rhythm resumed promptly after the ablative procedure (Fig 4). In patient 8 sinus rhythm temporarily disappeared, with a low atrial rhythm at 45 beatslmin and normal AV conduction, and recovered on the second postoperative day. Atrioventricular conduction was satisfactory in every patient. The unique postoperative complication was in patient 7, who had convulsions that abated after barbiturate perfusion, antiedema agents, and controlled hypothermia; computed tomographic scan performed on the fifth postoperative day showed cerebral edema but no eviden-e of brain damage. All patients were free from tachycardia and without medications 16 to 164 months after operation (as of December 31, 1991). Chest roengtenograms showed progressive reduction of the cardiac diameters in the patients showing preoperative cardiomegaly (Fig 5).

Comment The possibility of spontaneous remission of the EAT, especially in younger patients [2, 4, 6, 151, suggests the application of pharmacological trials as a first-choice treatment of the arrhythmia. Many patients, though, require invasive procedures because they are unresponsive to several drugs, are at risk for syncope due to hemodynamic derangement during tachycardia, or develop cardiomegaly.

The feasibility of catheter ablation of the focus in the treatment of EAT has been suggested by Gillette and associates [16] and Davis and colleagues [17]. This undoubtedly promising procedure is clearly indicated whenever possible (right-sided, single focus); nevertheless, its efficacy is still around 40% to 50% [16] and is strictly dependent on the operator’s skill and experience. The surgical approach has the clear advantages of direct epicardial mapping of the whole atrial surface and tailored surgical ablation of the focus. Surgical treatment of EAT aims to remove the arrhythmogenic focus or to confine the arrhythmia within limited atrial segments. Several surgical techniques have been devised for this purpose. Surgical isolation was described originally by Coumel and associates [14] for a focus close to pulmonary vein ostia and is indicated for foci adjacent to structures that may be damaged by clamping or suturing, like the AV junction or the pulmonary veins or caval ostia. Direct ablation, described by Wyndham and co-workers [18]and Josephson and colleagues [19], is easily feasible if the focus is located on the right or left appendage or on the right atrial free wall; implantation of a pericardial or artificial patch may be necessary after ablation of foci on the atrial septum or when atrial reconstruction is difficult. As a direct derivation of surgical ablation, cryoablation may be employed in easily approached sites, as right atrial or left atrial roof locations; in these cases, it must be remembered that foci located on the interatrial septum show a similar activation pattern, and this must be ruled out in advance to extend cryoablation to the interatrial septal surface. Cryoablation may be employed to safely ablate foci close to the sinus or AV nodes, being guided in this by on-line electrocardiographic monitoring. Atrial electrical isolation [20-221 may be employed for multiple right or left atrial foci, or for left atrial sites that may be difficult to approach by means of limited procedures, as between the pulmonary vein ostia.

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An important feature is the possible association of different supraventricular arrhythmias that may require additional antiarrhythmic procedures. In 1 of our patients (patient 7) who had an atrial septa1 defect and paroxysmal atrial flutter associated with an ectopic focus close to the right inferior pulmonary vein, we performed isolation of the right atrial appendage and of the ectopic focus as a single block. General anesthesia, hypothermia, or surgical manipulation may curb the automatic activity of the ectopic focus, thus making intraoperative atrial mapping impossible. Therefore, careful operative behavior (gentle handling of the heart, minimization of heart cooling, light anesthesia) enhances the possibility of satisfactory atrial mapping. Multielectrode computerized mapping may be helpful in mapping nonsustained runs of EAT. Operative procedures must be tailored to the specific focus location, and have to conjugate the need of sure ablation of the focus with the safeguard of the sinoatrial function as well as intraatrial and AV conduction.

References A

B

Fix 5. (Patient 1 .) Comparison between preoperative (A) chest roentgenogram and one taken 6 months after operation ( B ) , showing inarkcd rtduction of cardiac dinzeizsions after operation. Multifocal EAT has been described as difficult to correct by some authors [23]. We think that in such cases limited procedures may be inadequate and generous cumulative ablation or isolation procedures are advisable to minimize the risk of recurrences. Radiofrequency AV node modification may be added to control postoperative recurrences D81.

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