Temporary Electrode Research Articles

Temporary adjustable defibrillator electrodes: an alternative method for the treatment of postoperative arrhythmias after heart surgery

Supraventricular and ventricular tachycardias are common and serious postoperative complications early after cardiac surgery. We introduce a new temporary adjustable defibrillation electrode (TADE) for internal low-energy cardioversion/defibrillation of postoperative atrial and ventricular tachyarrhythmias. Evaluation of the new electrode was performed in ten open-chest beagles with a mean weight of 25.5 kg. The electrodes were first positioned on the left and right atrium. Atrial fibrillation (AU) was induced via a bipolar temporary heart wire. Atrial defibrillation thresholds (DFT's) were measured according to a step-down shock protocol (5 J-0.4 J). Thereafter, the electrodes were adjusted and positioned on the right and left ventricle. Ventricular fibrillation (VF) was induced and DFT's were recorded the same way. For termination of AF, mean DFT's were 0.4 +/- 0 J (lowest possible shock level) with a mean shock impedance of 70 +/- 7.6 omega. VF was terminated with a mean DFT of 3 +/- 1.1 J with a mean impedance 56.1 +/- 7.9 omega. Complete transcutaneous removal of the electrodes was possible in all animals without any complications. Successful low-energy termination of AF and VF is possible with the tested temporary adjustable electrode. A clinical study is planned for further evaluation.

Adjustable atrial and ventricular temporary electrode for low-energy termination of tachyarrhythmias early after cardiac surgery.

Supraventricular and ventricular tachycardias are common and serious postoperative complications early after cardiac surgery. We introduce a completely removable temporary adjustable defibrillation electrode (TADE) for low energy cardioversion/defibrillation of postoperative atrial and ventricular tachyarrhythmias. The electrode consists of three loops of steel wires connected to one steel wire, which are movable within an isolation sheet for adjusting the active surface to the individual size of the heart chambers. Evaluation of the electrode was performed in 10 open-chest beagles with a mean weight of 25.5 kg. The electrodes were first positioned on the left and right atrium. Atrial fibrillation (AF) was induced via a bipolar temporary heart wire. Atrial defibrillation thresholds (DFTs) were measured according to a step-down shock protocol (5-0.4 J). Thereafter, the electrodes were adjusted and positioned on the right and left ventricle. Ventricular fibrillation (VF) was induced and DFTs were recorded the same way. Aortic flow and pressure and left ventricular pressure were continuously monitored throughout the experiment. For termination of AF, mean DFTs were 0.4 +/- 0 J (lowest possible shock level) with a mean shock impedance of 70 +/- 7.6 ohms. VF was terminated with a mean DFT of 3 +/- 1.1 J with a mean impedance 56.1 +/- 7.9 ohms. Complete transcutaneous removal of the electrodes was possible in all animals without any complications. In conclusion, successful low energy termination of AF and VF is possible with the tested temporary adjustable electrode. A clinical study is planned for further evaluation.

Performance of temporary epicardial stainless steel wire electrodes used to treat atrial fibrillation: a study in patients following open heart surgery.

AF is the most common arrhythmia following open heart surgery. Transthoracic cardioversion is used when pharmacological treatment fails to restore SR, or is ineffective in controlling ventricular response rate. We report on the performance of temporary atrial defibrillation wire electrodes implanted on the epicardium of patients undergoing open heart surgery. Epicardial stainless steel wire electrodes for both pacing/sensing and atrial defibrillation were placed at the left and right atrium during open heart surgery in 100 consecutive patients (age 65 +/- 9 years; male/female 77/23). Electrophysiological studies performed postoperatively revealed a test shock (0.3 J) impedance of 96 +/- 12 omega (monophasic) and 97 +/- 13 omega (biphasic). AF was induced by burst stimulation in 84 patients. All patients were successfully converted to SR. The mean energy of successful shocks was 3.1 +/- 1.9 J. Atrial pacing and sensing were accomplished in all patients. Pacing threshold was 1.9 +/- 1.7 V (0.5 ms) in the left atrium and 2.1 +/- 2 V in the right atrium. P wave sensing was 2.5 +/- 1.6 mV in the left atrium and 2.3 +/- 1.4 mV in the right atrium. No complications were observed with shock application, nor with lead extraction. Atrial defibrillation using temporary epicardial wire electrodes can be performed successfully and safely in patients following cardiac operations. The shock energy required to restore SR is low. Electrical cardioversion in the absence of anesthesia should be feasible.

Electroneurography during facial nerve expansion

With the use of tissue-expansion techniques, it is possible to elongate the facial nerve without impairing its function. The rate of expansion is limited by ischemic events imposed by stretching of the nerve and by anatomic characteristics of the nerve segment. In this study, we used various electroneurography techniques to determine the first sign of facial dysfunction during expansion. The main objective of the study was to ascertain test-retest variability of electroneurography techniques. Facial nerves were expanded in 16 cats with the use of a tissue expander secured more deeply to the main trunk. We conducted electroneurography measurements with the use of surface electrodes, temporary needle electrodes, and permanently implanted electrodes. Technique-dependent variations encountered with the surface electrodes made this method unreliable. Using implanted electrodes, we noted gradual worsening of the compound-action potential amplitude with increasing expansion. During acute expansion, reduction in compound-action potential amplitude was correlated with clinically observed deterioration of facial-nerve function. In this study, electroneurography with implanted electrodes was found to be the most reliable predictor of the rate of successful facial nerve expansion. (Otolaryngol Head Neck Surg 1998;119:603-8.)

Internal atrial defibrillation - a new treatment of postoperative atrial fibrillation.

Atrial fibrillation (AF) commonly occurs following open heart surgery and may delay hospital discharge. Transthoracic electrical cardioversion is used when medical treatment is ineffective or associated with side effects. Traditionally general anesthesia is required. The aim of this multicenter study was to examine the feasibility and efficacy of low-energy atrial defibrillation using temporary epicardial defibrillation wire electrodes. Epicardial stainless-steel defibrillation wire electrodes were sutured onto the left and right atrium during open heart surgery in 238 patients (age 64+/-9 years; 180 males). In case of postoperative AF R-wave synchronous low-energy shocks (0.6-10.8J) were applied to achieve cardioversion without anesthesia. Implantation of the electrodes added 4.3+/-2.8 minutes to the operating time. During the hospital stay AF occurred in 47 patients (20%) at 2.1+/-1.3 days postoperatively. Fifty-one episodes of AF occurring in 44 patients were treated by atrial defibrillation. Primary success rate of cardioversion was 33/51 (65%). Early recurrence of AF (within 60 seconds after defibrillation) developed in 15 patients. Seven of these 15 patients were successfully defibrillated later on. Overall success rate was 40/51 (78%). The mean energy of successful shocks was 5.8+/-2.7 J. A mean of 2.3+/-1.7 shocks were applied per patient. The shocks were well tolerated by the patients in the absence of anesthesia. No complications were observed with shock application or with lead extraction. Atrial defibrillation using temporary epicardial wire electrodes can be performed safely and effectively in patients following cardiac surgery. The shock energy required to restore sinus rhythm is low.

Low-energy cardioversion with epicardial wire electrodes: new treatment of atrial fibrillation after open heart surgery.

Atrial fibrillation (AF) is the most common arrhythmia after open heart surgery. Traditional treatment with a range of antiarrhythmic drugs and electrical cardioversion is associated with considerable side effects. The aim of this study was to examine the feasibility and efficacy of low-energy atrial defibrillation with temporary epicardial defibrillation wire electrodes. Epicardial defibrillation wire electrodes were placed at the left and right atria during open heart surgery in 100 consecutive patients (age 65+/-9 years; male to female ratio 67:23). Electrophysiological studies performed postoperatively revealed a test shock (0.3 J) impedance of 96+/-12 omega (monophasic) and 97+/-13 omega (biphasic). During their hospital stay, AF occurred in 23 patients (23%) at 2.1+/-1.3 days postoperatively. Internal atrial defibrillation was performed in 20 patients. Of these patients, 80% (16/20) were successfully cardioverted with a mean energy of 5.2+/-3 J. Early recurrence of AF (< or =60 seconds after defibrillation) developed in 8 patients. Five patients had multiple episodes of AF. In total, 35 episodes of AF were treated, with an 88% success rate. Only 6 patients (30%) required sedation. No complications were observed with shock application or with lead extraction. Atrial defibrillation with temporary epicardial wire electrodes can be performed safely and effectively in patients after cardiac operations. The shock energy required to restore sinus rhythm is low. Thus, patients can be cardioverted without anesthesia.

Temporary epicardial atrial pacing electrodes: duration of effectiveness based on position.

To investigate the duration of effectiveness in the postoperative period of temporary epicardial atrial pacing electrodes on the right atrium, based on position. The function of temporary epicardial atrial pacing electrodes were examined in 55 patients undergoing coronary artery bypass grafting from March 20, 1996, to July 31, 1996, at Allegheny University Hospitals, Hahnemann Division, Philadelphia, PA. There were 41 male and 14 female patients. The mean age was 71 years (range 35 to 86 years). Two atrial and two ventricular temporary epicardial pacing electrodes were placed at the termination of cardiopulmonary bypass. One atrial electrode was placed on the body of the right atrium at the junction of the superior vena cava (body electrode); the other was passed through the pursestring of the atrial cannulation site (appendage electrode). The mean thresholds for the atrial body electrodes on the operative day and postoperative days 1 and 2 were 4.96, 6.67, and 6.80 mA, respectively. The mean thresholds for the atrial appendage electrodes were 5.98, 7.50, and 8.59 mA, respectively. Temporary epicardial atrial pacing electrodes are more effective when the wires are placed in the atrial body of the right atrium than if they are wrapped within the pursestring of the right atrial appendage. As a result of these findings, the common practice of placing the pacing wire through pursestring tissue should be abandoned.

Temporary Epicardial Atrial Pacing Electrodes: Duration of Effectiveness Based on Position

To investigate the duration of effectiveness in the postoperative period of temporary epicardial atrial pacing electrodes on the right atrium, based on position.The function of temporary epicardial atrial pacing electrodes were examined in 55 patients undergoing coronary artery bypass grafting from March 20, 1996, to July 31, 1996, at Allegheny University Hospitals, Hahnemann Division, Philadelphia, PA. There were 41 male and 14 female patients. The mean age was 71 years (range 35 to 86 years). Two atrial and two ventricular temporary epicardial pacing electrodes were placed at the termination of cardiopulmonary bypass. One atrial electrode was placed on the body of the right atrium at the junction of the superior vena cava (body electrode); the other was passed through the pursestring of the atrial cannulation site (appendage electrode).The mean thresholds for the atrial body electrodes on the operative day and postoperative days 1 and 2 were 4.96, 6.67, and 6.80 mA, respectively. The mean thresholds for the atrial appendage electrodes were 5.98, 7.50, and 8.59 mA, respectively.Temporary epicardial atrial pacing electrodes are more effective when the wires are placed in the atrial body of the right atrium than if they are wrapped within the pursestring of the right atrial appendage. As a result of these findings, the common practice of placing the pacing wire through pursestring tissue should be abandoned.

Temporary Atrial Electrode for the Treatment of Supraventricular Tachycardia After Cardiac Operations

Background. Supraventricular tachycardia is a common postoperative complication early after cardiac operations. A temporary atrial patch electrode for low-energy atrial defibrillation was developed in 1992 and subsequently tested.Methods. The electrode first was tested and removed intraoperatively during open heart operations in 10 patients (phase I). After the intraoperative testing, the temporary atrial patch electrode was implanted in 20 patients for postoperative termination of spontaneous episodes of supraventricular tachycardia (phase II). When supraventricular tachycardia occurred, biphasic shocks (1.2 to 5 J) were applied and the atrial defibrillation thresholds were measured.Results. In phase I, the mean intraoperative atrial defibrillation threshold was 1.6 ± 1.4 J, with a mean shock impedance of 64 ± 7.3 Ω. In phase II, 6 of 20 patients (30%) had 7 episodes of atrial fibrillation (n = 6) and atrial flutter (n = 1) after operation. In 5 patients, the supraventricular tachycardia could be converted to a sinus (n = 5) or normofrequent atrioventricular rhythm (n = 1). The mean postoperative defibrillation threshold was 2.7 ± 2.1 J, with a mean shock impedance of 50.2 ± 6.8 Ω.Conclusions. The temporary atrial patch electrode allows low-energy defibrillation of episodes of atrial fibrillation. It may serve as an alternative therapeutic option for the treatment of supraventricular tachycardia.

Effects of spinal cord stimulation on coronary blood flow velocity.

Spinal cord stimulation (SCS) has been used in the treatment of severe angina pectoris since the 1980s. Several studies have shown both an antianginal and an anti-ischaemic effect. There are several theories about the mechanism behind the anti-ischaemic effect of SCS, including the possibility that it is dependent on an increase in coronary flow velocity. To determine if there were effects of SCS on coronary flow velocity during cardiac stress. Eight patients with severe anginal pain secondary to coronary artery disease who had been implanted with an SCS device were included in the study. In addition, four patients with syndrome X were examined. If possible, a Doppler guidewire was placed in the vessel corresponding to the ischaemic area revealed on a prior myocardial scintigram. A temporary pacemaker electrode was placed in the right atrium. Atrial pacing started at 80 beats/min and increased by 10 beats/min every 2 min until the patient experienced moderate angina; the pacing frequency was then maintained at the same level. After 2 min of pacing at this frequency, SCS treatment commenced; after a further 5 min, pacing was stopped. Throughout the procedure, coronary flow velocity, assessed as average peak velocity (APV), was monitored continually. APV increased during pacing in all the patients with coronary artery disease (mean increase 53%; P < 0.02). There were no significant changes in APV during maximum pacing frequency when stimulation was introduced. The results of this study do not support the theory that the anti-ischaemic effect of SCS is dependent on an increase in coronary flow velocity.

Psychological Variables Associated With Outcome of Spinal Cord Stimulation Trials

Study Design. This is a prospective study designed to identify psychological factors associated with response to spinal cord stimulation (SCS) trial. Summary of Background Data. In most centers, implantation of a permanent SCS system is preceded by a trial of a temporary stimulating electrode. Yet, even among those who report greater than 50% pain reduction during trial, a significant number of these patients fail to receive long-term pain relief from the permanent system. Because mood disorders can alter pain report, we hypothesized that refined definition of the psychological factors associated with SCS success could result in improved selection of candidates for SCS trial. Methods. The study sample consisted of 43 chronic pain patients (72% failed back surgery syndrome, 77% with radiating low back pain) who were referred for implantable pain management. Following psychological evaluation, patients were admitted for a three-day inpatient trial of SCS. Report of at least 50% pain relief during trial was considered a success and resulted in implantation of the permanent stimulator. Patients were retrospectively divided into two groups: those whose pretrial pain was relieved by at least 50% ("success") and those whose pain was relieved by less than 50% ("failure"). Results. Univariate t-test or chi-square analyzes of group means of an extensive psychological battery followed by a global, stepwise logistic regression model of trial outcome was used to analyze between group results of a psychological test battery. MMPI depression and mania subscores were found to be significantly elevated among the two outcome groups (p = 0.007 and 0.025, respectively). Conclusions. Patient mood state is an important predictor of trial outcome. Specific indicators of SCS trial outcome are the MMPI depression and mania subscale scores with successful trials being associated with individuals who are less depressed and have higher energy levels.

Care and safety of pacemaker electrodes in intensive care and telemetry nursing units

Temporary pacing leads with electrodes are a potential risk, because microshock inadvertently transmitted across the catheter or wire can paradoxically cause lethal dysrhythmias. Much attention has been paid to this complication in clinical guidelines, but little is known about actual practices used to protect patients. A national survey was done to describe current practices related to the care of patients with temporary epicardial or transvenous pacing catheters. The survey focused on environmental factors that affect generation of static electricity, equipment used with temporary pacing, and nursing practices used when handling temporary pacing electrodes. The Pacemaker Electrical Care and Safety Survey was developed, validated, and pilot tested before it was mailed to all 895 hospitals that perform cardiac surgery. Surveys were sent to the coronary care unit, cardiac surgical ICU, and telemetry units of each hospital. Responses were received from 476 units representing 388 (43%) of the 895 institutions. Most respondents reported using gloves, although few hospitals had policies mandating this practice. The insulating materials used most often, in order, were a glove or finger cot, tape, and gauze. Few units (25%) use any measure to reduce static electricity generated by movement over carpeting. Little attention was paid to insulating exposed epicardial temporary pacing electrodes at the generator. Temporary pacing electrodes were usually handled in an electrically safe manner; however, little attention was paid to environmental sources of microshock or connections between the generator and the cable. Although the respondents reported using a variety of insulating materials, the ideal cover for the exposed tips of the electrodes has not yet been determined.

Spontaneous onset of type I atrial flutter in patients

Objectives. This study sought to characterize the spontaneous onset of atrial flutter in patients.Background. Temporary epicardial electrodes are routinely placed on the atria of patients at the time of open heart surgery and brought out through the anterior chest wall for potential diagnostic and therapeutic use in the postoperative period. We utilized these electrodes to study the spontaneous onset of type I atrial flutter in 16 patients in the postoperative period after open heart surgery.Methods. Twenty-seven episodes of the spontaneous onset of type I atrial flutter from sinus rhythm were studied in these 16 patients by recording bipolar atrial electrograms simultaneously with at least one electrocardiographic lead during each episode.Results. In all 27 episodes, the onset of type I atrial flutter was through a transitional rhythm of variable duration (mean 9.3 s) precipitated by a premature atrial beat. In 21 episodes, the transitional rhythm was atrial fibrillation; in 3 episodes it was type II atrial flutter that appeared to generate atrial fibrillation; and in 3 episodes it was a brief (3 to 6 beats), rapid, irregular arrhythmia.Conclusions. Type I atrial flutter does not start immediately after a premature atrial beat. Rather, it starts after a transitional rhythm that is usually atrial fibrillation. Extrapolating from mapping studies of the onset of atrial flutter in the canine pericarditis model, we suggest that a transitional rhythm is required for the initiation of type I atrial flutter because during that rhythm, the requisites for development of the atrial flutter reentry circuit evolve.

Sensitivity to Mivacurium in a Patient with Mitochondrial Myopathy

Sensitivity to Mivacurium in a Patient with Mitochondrial Myopathy

Successful atrial defibrillation with very-low-energy shocks by means of temporary epicardial wire electrodes

Sustained atrial fibrillation is very common after cardiac surgical procedures. We hypothesized that atrial defibrillation could be accomplished consistently and safely by means of low-energy shocks delivered by temporary stainless steel wire electrodes placed at the time of the operation. Sterile pericarditis was created in five mongrel dogs (20.9 ± 2.1 kg), and pairs of standard temporary stainless steel wire electrodes were placed on the right atrial appendage, on Bachmann's bundle, and on the right ventricular apex for pacing, sensing, and recording. Temporary stainless steel wire electrodes, insulated except for the distal 6 cm and used to deliver defibrillation shocks, were placed adjacent to both atrial free walls and secured to the pericardium. All electrodes were brought out through the skin, and the sternotomy was closed. Dogs were tested in the conscious state on postoperative day 2. Sustained atrial fibrillation was induced by rapid atrial pacing. A customized software program was used to control the defibrillator, which delivered R wave–synchronous biphasic shocks to the atria through the temporary defibrillation electrodes. The shock intensity began at 50 volts and was increased by 10-volt increments until atrial fibrillation was terminated. Atrial fibrillation was terminated in all dogs at 112 ± 7 volts, with an energy of 0.42 ± 0.07 joule and an impedance of 67.8 ± 4 ohms (all values mean ± standard error of the mean). The mean percent success for atrial defibrillation at this minimal threshold was 49%. Thus at low-threshold voltages atrial fibrillation could be terminated with every other shock. A 25% increase in the minimal threshold voltage improved the conversion rate to 73% (mean energy 0.66 ± 0.19 joule and mean impedance of 67 ± 3.8 ohms). No complications were detected with the use of the electrodes or after their removal on the seventh postoperative day. One instance of electrode migration on the right atrial free wall was detected by roentgenography, but this did not adversely affect atrial defibrillation threshold. No ventricular arrhythmias or hemodynamic complications were noted during shock delivery. We conclude that successful conversion of atrial fibrillation to sinus rhythm can be achieved consistently with shock energies below 0.5 joule delivered with temporary epicardial defibrillation wire electrodes in this canine pericarditis model. These results suggest that this approach to the management of sustained atrial tachyarrhythmias has considerable promise in the management of atrial fibrillation in patients who have had cardiac operations. (J T HORAC C ARDIOVASC S URG 1996;111:392-8)

Laparoscopic implantation of temporary electrodes for bladder stimulation in dogs

Five female mongrel dogs were used in an acute animal experiment. Under general anesthesia two monopolar wire electrodes armed with needles on either side were implanted into the bladder wall, the leads of both electrodes were then pulled through the abdominal wall. Filling of the bladder and intravesical pressure measurement were achieved through a suprapublic percutaneous cystostomy. Electrostimulation was carried out using the XEJ-2 experimental electroejaculator (biphasic pulses, pulse width 2.5 msec, approximately 70 mAmp, 50 Hz). The pressure changes within the bladder following electrostimulation were recorded, the effect of stimulation was observed endoscopically. Electrostimulation of the bladder wall resulted in micturition in all cases, showing an initial pressure peak at the commencement of electrostimulation followed by a decrease after onset of evacuation. We believe that laparoscopic implantation of temporary wire electrodes followed by percutaneous electrostimulation may open up new possibilities for bladder rehabilitation as well as for diagnostic investigations into the contractile capabilities of the bladder.

Laparoscopic implantation of temporary electrodes for bladder stimulation in dogs

Laparoscopic implantation of temporary electrodes for bladder stimulation in dogs

Atrial defibrillation using temporary epicardial defibrillation stainless steel wire electrodes: Studies in the canine sterile pericarditis model

This study sought to determine whether temporary epicardial wire electrodes can be used safely and effectively to defibrillate the atria with low energy shocks in the absence of anesthesia. Atrial fibrillation after open heart surgery is a significant clinical problem. Twelve dogs with sterile pericarditis were studied. In the first group (6 dogs, bilateral thoracotomy group), a wire electrode, insulated except for the distal 6 cm, was placed on the epicardial free wall of each atrium. Each end of the bare wire was then sutured to the parietal pericardium. In the second group (6 dogs, median sternotomy group), the wire electrodes were kept in place by a double loop of Prolene placed around the distal tip of the bare wire and sewn to the overlying parietal pericardium. In the bilateral thoracotomy group, atrial defibrillation thresholds (defined as < 90% and > 10% successful defibrillation of 20 shocks at a given delivered energy) were obtained in anesthetized dogs using the wire electrodes with the chest closed and open and using two transvenously placed catheters with coil electrodes in the distal 6 cm (one in the coronary sinus and the other in the right atrial appendage) with the chest open. In the median sternotomy group, thresholds were obtained in minimally sedated animals without reopening the chest. A 25% increase above threshold shock was also used to determine a new percent success. After 4 days, the wire electrodes were removed by pulling on the external ends. At the time of removal, blood pressure and heart rate were monitored for 30 min, after which dogs were killed and their hearts sent for histopathologic study. For all dogs, chest radiographs were obtained postoperatively and on study days. Atrial defibrillation using the wire electrodes was successful in all dogs at a mean (+/- SE) voltage of 112 +/- 9 V, with an energy level of 0.46 +/- 0.07 J and an impedance of 59.3 +/- 5 ohms. The mean percent success at the atrial defibrillation threshold was 36 +/- 5%. The 25% increase in defibrillation voltage improved the mean percent success to 73% (mean energy 0.66 +/- 0.19 J). No clinical or hemodynamic complications were observed during shock delivery, and no ventricular arrhythmias were induced during the shocks. No complications followed wire electrode removal. Histopathologic analysis showed no structural damage. The atrial defibrillation threshold obtained using temporary epicardial wire electrodes for atrial defibrillation is < 1 J in dogs. Atrial defibrillation using temporary epicardial wire electrodes can be performed safely, quickly and reliably without the need for anesthesia or antiarrhythmic agents. The wire electrodes can be removed without adverse hemodynamic or structural consequences. These data provide a basis for testing atrial defibrillation using epicardial wire electrodes in patients after open heart surgery.

Atrioventricular sequential pacing using transesophageal atrial pacing in combination with a temporary DDD pacemaker for atrial tracking and ventricular pacing

To determine whether atrioventricular (A-V) sequential pacing can be accomplished using transesophageal atrial pacing (TAP) in combination with a temporary DDD pacemaker for tracking the TAP stimuli and pacing the ventricle via temporary epicardial electrodes. Prospective; patients enrolled consecutively. Nonuniversity teaching hospital. Ten adults undergoing cardiac surgery requiring cardiopulmonary bypass. Two to six hours after the termination of cardiopulmonary bypass, atrial pacing was initiated via TAP. The atrial system of a temporary DDD pacemaker was connected to surface electrocardiogram (ECG) electrodes. If the temporary pacemaker could track the TAP stimuli and emit pacing stimuli resulting in ventricular capture, A-V sequential pacing was considered to have occurred. The patients were immediately restudied in the same manner with the change that the temporary DDD pacemaker sensed the TAP stimuli via temporary atrial bipolar epicardial electrodes rather than surface ECG electrodes. Dual pacemaker A-V sequential pacing was accomplished in 17 out of 20 attempts. The atrial system of the temporary DDD pacemaker was able to sense the TAP stimulus via temporary atrial bipolar epicardial leads in 10 out of 10 patients and directly from surface ECG electrodes (right arm/left arm) in 7 out of 10 patients. This report demonstrates that it is possible to A-V sequentially pace using TAP in combination with a temporary DDD pacemaker for tracking the TAP stimulus and pacing the ventricle via temporary epicardial leads. This technique may be useful when A-V sequential pacing is needed and functional temporary atrial leads are not available.

Acute hemodynamic effects of atrio-biventricular pacing in humans

Standard postoperative dual-chamber pacing uses ventricular leads placed on the right ventricle that produce dysynchronous ventricular activation and contraction. The hypothesis that simultaneous stimulation of both ventricles by atrio-biventricular pacing improves hemodynamic performance compared with that observed with standard atrio-monoventricular pacing was tested in 18 patients 12 to 36 hours after elective coronary artery revascularization. Temporary epicardial pacing electrodes were placed on the right atrium and into anterior paraseptal sites on the right and left ventricle. Simultaneous biventricular activation was documented by fusion morphology of surface electrocardiograms and by isochronal epicardial activation mapping during biventricular pacing. Hemodynamic data were acquired after 10 minutes of pacing at a fixed overdrive rate during atrial pacing and during dual-chamber pacing using unipolar right ventricular, unipolar left ventricular, and bipolar biventricular (left ventricular cathode) leads. Atrio-biventricular pacing increased cardiac index and decreased systemic vascular resistance compared with atrial pacing and with atrio-right ventricular and atrio-left ventricular dual-chamber pacing (p < 0.05). These data support the use of atrio-biventricular pacing employing paraseptal electrodes to optimize hemodynamic performance.