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Ann Thorac Surg 1999;67:952-958
© 1999 The Society of Thoracic Surgeons
a Division of Cardiothoracic Surgery, Department of Surgery, College of Physicians & Surgeons, Columbia University, New York, New York, USA
Accepted for publication September 15, 1998.
Address reprint requests to Dr Goldstein, Division of Cardiothoracic Surgery, Columbia University, 622 West 168th St, Box 268, New York, NY 10032
e-mail: djg9{at}columbia.edu
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Abstract |
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 TopFootnotes Abstract IntroductionPatients and methodsResultsCommentReferences |
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Methods. We retrospectively reviewed our experience in 9 patients who had those procedures. Five patients had pacing from the coronary sinus, and 4 by transatrial puncture.
Results. Seven of the 9 patients had DDD pacing. Low acute pacing thresholds and satisfactory sensing levels were obtained with both approaches. One instance of high stimulation threshold (20%) occurred in the coronary sinus group and none in the transatrial puncture group. One patient in the transatrial puncture group died from unrelated causes. No malignant arrhythmias, pneumothorax, diaphragmatic pacing, or infectious complications have been observed.
Conclusion. These unconventional approaches are safe, relatively simple, and reliable. Although the short-term follow-up is favorable, long-term follow-up is necessary to ascertain the relative merit of these approaches.
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Introduction |
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TopFootnotesAbstractIntroductionPatients and methodsResultsCommentReferences |
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To avoid epicardial implantation, we used the following two approaches to reach the atrial and ventricular endocardium in patients in whom conventional transvenous endocardial pacing is not possible: (1) transatrial puncture and passage of pacing leads into the atrial or ventricular endocardium in patients with no superior systemic venous access to the right atrium and (2) ventricular pacing from the coronary sinus (CS) or its tributaries for patients with inaccessible right ventricles (eg, recipients of Fontan operations, presence of tricuspid prosthesis).
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Patients and methods |
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TopFootnotesAbstractIntroductionPatients and methodsResultsCommentReferences |
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Surgical technique
Transvenous coronary sinus pacing
With appropriate anesthesia, the skin and subcutaneous tissues are incised. Hemostasis and venous access via cephalic cutdown or subclavian puncture is obtained. Insertion of a pacing lead into the CS involves the following issues: where the CS os is located, how to steer the catheter to the os, how to recognize when the catheter enters the CS, and how to steer the catheter within the CS.
If marked anatomic abnormalities exist, preoperative review of available angiograms and echocardiograms is mandatory to best define the location of the CS os in three dimensions, and to identify the left-sided superior vena cava. If a pacing lead enters a left superior vena cava, it will migrate into the CS oriented centrally into the right atrium. This orientation precludes passage of the pacing lead into the tributaries of the CS.
By using an anteroposterior fluoroscopic view, the os is located in the extreme caudad, left lateral aspect of the right atrium. The os normally will be inferior and posterior to the point at which a catheter crosses the tricuspid valve to the right ventricle, but the anteroposterior view does not provide anteroposterior localization, which must be obtained either with oblique fluoroscopic views or with trial and error techniques, including stylet bends directing the lead leftward and posteriorly.
Cannulation of the os requires venous access from the left cephalic, subclavian, or external jugular vein. The degree of difficulty is vastly increased by a right-sided venous approach, to the point that this should not be attempted unless there is no left-sided option. The reason for this is that a simple 90-degree bend in the stylet will take a catheter to the CS from the left, whereas a compound "S" bend in the stylet is required from the right.
Finding the os with the catheter is facilitated by understanding the principles of steering a pacing catheter to a precise spot in the right atrium or ventricle. Optimally, for finding the CS, the stylet inserted into the lead should be bent to the precise curvature needed from the right atrium–superior vena cava junction to the CS, roughly a 90-degree bend to the left, with a slight reverse (downward) curvature over the last 4 cm. A slight posterior curvature is also desirable. If the lead does not enter the CS with a few tries, the stylet should be pulled back 3 cm and the attempt repeated. If that fails, the curvature of the stylet should be modified. The perception of the operator should be that the lead is moving over the surface of the right atrium caudad to the tricuspid valve. As the stylet is advanced and withdrawn within the lead, the curvature of the lead and location of its tip will change. These maneuvers give the operator total control over where the lead is going. With some practice and modification to the curvature of the stylet, the entire endocardial surface in question can be explored until the lead tip drops into the CS. When the lead is properly positioned, we use the positive fixation feature to secure the lead against displacement. If the patient has not had prior operations, the possibility of bleeding and perforation related to this maneuver must be borne in mind. Therefore, we cannot recommend use of active fixation leads in patients with a free pericardial space.
Entry into the CS can be confirmed on the basis of anatomic or functional information. If ventricular pacing is obtained at a low voltage, the objective of the operation has been achieved, and the precise location is of secondary importance. If ventricular pacing is not achieved, pacing can be attained by advancing the lead forward along the CS until the lead passes around the obtuse margin of the left ventricle; alternatively, the lead can be directed inferiorly and perpendicular to the CS into venous tributaries. Both of these maneuvers are aided by confidence that the lead is truly in the CS. Redirecting the fluoroscope to obtain a left-sided anterior oblique view and to confirm posterior location is helpful in this regard. We are more concerned that the lead is encased by a physical structure that will allow it to follow a restricted physical path. This situation can be confirmed by withdrawing the stylet for 2 to 3 cm and attempting to cause the lead to buckle on itself by advancing it. If the lead is in the right ventricle, this is easily accomplished; loops and knots are likely to occur. In the CS, however, the lead remains relatively straight.
Pacing threshold and R-wave amplitudes are measured after stylet removal, and absence of diaphragmatic stimulation at 10 volts of output is confirmed. If a DDD pacemaker is used, the atrial lead is screwed into the atrial appendage or lateral atrial wall. In pediatric patients a redundant loop is created in the atrial cavity to allow for growth. The leads are then stabilized with sutures at the venous access site and meticulous hemostasis is attained. The pacemaker generator is connected and inserted into a pocket created subcutaneously and function is confirmed. The wound is closed in layers. Perioperative antistaphylococcal antibiotics are administered. Temporary pacing or chronotropic drugs are continued for 24 hours in pacemaker-dependent patients.
Transatrial puncture
After adequate endotracheal anesthesia, access to the right atrium is obtained by median sternotomy or, preferably, by a limited right parasternal mediastinotomy. With fluoroscopic guidance, the right heart is visualized and the cartilage bed overlying the right atrium is excised. The internal thoracic artery is ligated if necessary to optimize exposure. The right atrium is punctured with a no. 7 stripaway introducer through a Prolene (Ethicon, Somerville, NJ) pursestring suture. The leads are placed with the aid of curved stylets and fluoroscopic guidance onto the atrial appendage, ventricular apex, or both. Pacing threshold and R-wave amplitudes are obtained as described for the CS procedure. The leads are stabilized at the access site. A subcutaneous pocket is fashioned in the right upper quadrant of the abdomen (Fig 1). Efforts are made to avoid pleural entry. If the pleura has been opened, a thoracotomy tube is left in place for 24 hours. The remainder of the procedure is the same as that for the CS approach.
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Results |
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TopFootnotesAbstractIntroductionPatients and methodsResultsCommentReferences |
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Pacemaker data
Details of pacemaker implantation appear in Table 3. All 5 patients with prior Fontan operations had DDD pacing to optimize univentricular physiology. Two of the 4 patients in the transatrial cohort had DDD pacing.
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Transatrial puncture cohort
Initial implantation threshold stimulation for the atrial leads was 1.4 ± 0.24 volts (95% CI, 0.6 to 2.19 volts) and 2.93 ± 0.8 mA (95% CI, 0.39 to 5.46 mA); P-wave amplitude averaged 2.2 ± 0.6 mV (95% CI, -0.39 to 4.79 mV). Mean implantation impedance was 544 ± 89 ohms (95% CI, 259 to 829 ohms). Ventricular stimulation threshold for the patients receiving transatrially placed endocardial ventricular leads was 1.4 ± 0.1 volts (95% CI, 0.13 to 2.67 volts) and 2.75 ± 0.25 mA (95% CI, -0.42 to 5.93 mA); average R-wave amplitude was 12 ± 5 mV (95% CI, -51.5 to 75.5 mV). Mean implantation impedance was 516 ± 83.5 ohms (95% CI, -544 to 1,577 ohms).
Follow-up
Coronary sinus
For patients who had CS ventricular pacing, high stimulation threshold (exit block) developed in one of five instances (20%). Follow-up for the CS cohort is between 2 months and 4.6 years. Three patients are alive; one died shortly after cardiac transplantation. One patient had placement of CS leads on two occasions. She first had insertion of an epicardial pacemaker at the time of Fontan repair; this lead fractured 4 years postoperatively, and she then had transvenous CS ventricular pacing. During repeat open heart operation for revision of the Fontan, a second ventricular epicardial lead was placed because of development of high threshold in the CS lead after 4.5 years of pacing. The CS catheter was left in place at that time. Approximately 2 years later, high pacing threshold again developed in her epicardial lead and she had successful placement of a second transvenous CS lead. Her original CS lead was left in place. Her CS lead was functioning well until the time of transplantation. The explanted heart was examined, and both CS leads were well fixated (Fig 2). No intrasinus clot was noted. The remaining 3 patients have maintained low chronic stimulation thresholds.
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For all 9 patients, there were no instances of malignant arrhythmias, pneumothorax, bleeding, diaphragmatic pacing, or infectious complications.
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Comment |
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TopFootnotesAbstractIntroductionPatients and methodsResultsCommentReferences |
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To avoid epicardial implantation in patients with inaccessible right cardiac chambers, we recently used two distinct approaches to secure permanent pacing, the transatrial passage of endocardial leads and ventricular pacing from the CS. The transatrial approach is well suited to patients with inaccessible right atria such as those with superior vena cava obstruction or patients who have had prior cavopulmonary shunting, transatrial puncture and passage of endocardial leads into the right atrium or ventricle (Table 4). There are few reports of this approach in the literature. Byrd and colleagues [6] first described the transatrial approach for extraction of infected pacing leads, and Westerman and van Devanter [7] first used this approach to establish permanent endocardial pacing. This effort was thereafter used successfully by Byrd and Schwartz [5] to establish DDD(R) pacing in 6 patients with contraindications for transvenous implants. Most recently, Hoyer and colleagues [8] used the transatrial approach in 5 children who had previous open heart operations. In all 5 patients only one lead was placed transatrially; in 3 patients, dual chamber pacing was established by epicardial placement of an atrial lead and transatrial insertion of the ventricular lead. Two of the three atrial epicardial leads failed necessitating conversion to a VVI pacing mode. Long-term low pacing thresholds were observed with up to 28 months of follow-up.
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As pointed out by Hoyer and colleagues [8], two potential long-term sequelae of the transatrial puncture approach include lead dislodgment with loss of capture secondary to cardiac growth, and thromboembolism. The latter appears unlikely, as no contact exists between the systemic veins and the pacing leads. Similarly, there is no reason to believe that this approach should increase the risk of pacemaker infection or endocarditis.
The coronary sinus approach was used successfully in patients with inaccessible right ventricles resulting from the presence of a Fontan circulation or a tricuspid prosthesis and in patients with accessible right ventricles unsuitable for endocardial pacing (Table 4). Although the CS has been at times used for atrial pacing [11, 12], ventricular pacing has only been described anecdotally in 3 patients, including 2 patients with existing tricuspid prostheses, and 1 patient with a Fontan circulation [13, 14]. Most recently, CS ventricular lead placement has been done in selected patients who had multisite pacing for the treatment of end-stage congestive heart failure [15].
In patients who had CS implantation, we used unipolar positive fixation leads. These leads have a small cross-sectional area and are flexible and more reliable than the bipolar, passive fixation counterparts [16, 17]. These properties facilitate lead maneuvering which is critical in small patients and in patients with previously reconstructed cardiac anatomy. Successful entry into the os of the CS can be enhanced by orienting the fluoroscope in a marked left anterior oblique position. In this manner, the lead is seen to advance into the CS along the posterior aspect of the heart. We could not use this technique until recently.
Our experience with ventricular pacing from the CS indicates that this approach is safe and feasible and can provide effective ventricular pacing. A major advantage over the epicardial approach is the avoidance of the morbidity associated with thoracotomy and general anesthesia. A theoretic concern is CS perforation in the immediate postoperative period. In our limited experience, we have not observed this complication and believe is less likely to happen in patients who have had prior cardiac operation and in whom extensive adhesions are present. For these reasons, however, we do not recommend use of active fixation leads in patients with free pericardial space. A second adverse effect is the potential development of CS thrombosis with long-term implantation. In this regard, postmortem examination of 5 patients who had CS lead implantations for atrial pacing [11, 12] and inspection of an explanted heart in 1 patient in the present series all found widely patent coronary veins with no obstruction to flow and no thrombi.
In patients with inaccessible right cardiac chambers who require implantation of permanent pacing systems, the transatrial approach for atrial and or ventricular pacing and the CS implantation for ventricular pacing are two alternative methods to epicardial pacing systems. Our preference for these approaches is based on the frequent development of high pacing threshold and occasional lead fracture in patients who have epicardial implantation. Nevertheless, thoracotomy and epicardial placement of pacing systems are likely to remain the method of choice for patients with inoperable septal defects in whom endocardial pacing carries a significant risk of thromboembolism. Similarly, for surgeons who infrequently insert pacemakers in infants and children, epicardial pacemaker placement will remain the favored approach [18]. Further experience with epicardial steroid eluting leads and alternative biomaterials might reduce the incidence of these complications.
Although there have been few cases reported by us and others, these unconventional approaches appear safe, relatively simple and reliable, and do not require additional hardware. Although short-term follow-up is favorable, long-term follow-up is necessary to ascertain the relative merit of these approaches.
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Footnotes |
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TopFootnotesAbstractIntroductionPatients and methodsResultsCommentReferences |
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References |
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TopFootnotesAbstractIntroductionPatients and methodsResultsCommentReferences |
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  F. A. Baciewicz Jr and K. Jackson Transatrial cardiac pacing Ann. Thorac. Surg., April 1, 2000; 69(4): 1301 - 1302. [Full Text] [PDF]
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