Temporary external DDD pacing after cardiac operations

Temporary atrial and ventricular pacing in the DVI, VVI, and AOO modes using atrioventricular sequential DVI devices is routinely used in cardiac operations. This study evaluated a new temporary external DDD pacemaker (Medtronic 5345 External Pulse Generator) capable of ten pacing modes. Thirty-nine devices have been applied to 38 adult patients (27 male, 11 female) after a variety of open heart procedures. Group 1 had atrial pacing wires placed 1.5 to 2.0 cm apart superiorly on the right atrium, group 2 had atrial wires placed 1.0 to 1.5 cm apart on the right atrial free wall, and group 3 had atrial wires placed on the right atrial free wall 0.8 cm apart, using a Silastic ring for fixation. Ventricular wires were placed on the free wall (group 1) or the diaphragmatic surface (groups 2 and 3) of the right ventricle. Postoperative atrial and ventricular sensing and pacing thresholds were obtained on return to the intensive care unit; analysis of variance demonstrated a significantly greater atrial sensing threshold in group 3. Four patients in group 1 permanently lost atrial sensing, 1 patient in group 2 intermittently lost atrial sensing at 24 hours with return at 36 hours postoperatively, and 1 patient in group 1 lost ventricular sensing capability. All other patients had adequate atrial and ventricular sensing capability documented until elective pacemaker removal (mean, 166 hours; range, 17 to 667.5 hours). Nineteen patients required some form of temporary pacing postoperatively; 11 patients demonstrated hemodynamic benefit from a pacing mode that is not available on the currently used DVI devices, and 7 of these required true DDD pacing capability. Six patients benefited from atrial pacing with adequate atrial sensing and simultaneous ventricular backup. Burst pacing with the device was used successfully to treat postoperative atrial flutter in 2 patients. We conclude that temporary external DDD pacing is feasible and effective in postoperative cardiac surgical patients. Atrial sensing is possible in most patients but electrode positioning is important for adequate thresholds. In some patients, hemodynamic as well as electrophysiologic improvement can be demonstrated with universal DDD pacing capability as compared with standard DVI pacing.     

Pervenous Atrial Electrode

“Atricor” P-synchronous pacemakers have been installed in 11 patients by the use of pervenous electrodes. At the follow-up, 8 patients still had P-synchronous pacemakers working, whereas in 2 cases “Ectocar” (“demand”) had been installed on account of non-functioning atrial electrodes. One patient received a temporary “demand” pacemaker because of cardiac surgery. In 1 patient, a pervenous atrial electrode has been used for atrial pacing as treatment for sinus bradycardia. This pacemaker has now functioned for 1 year. In 5 patients, surgical replacement of displaced atrial electrodes has been necessary. Proper fixation of the atrial electrode in the subclavian fossa is vital for successful P-synchronous pacing of longer duration.     

Interaction of an implanted pacemaker with a transesophageal atrial pacemaker: report of a case

We report an interaction of a transesophageal atrial pacemaker (TAP) with a permanently implanted pacemaker in a cardiac patient who had undergone ablative therapy for atrial tachyarrhythmia 5 years earlier. The patient’s permanent A-V pacemaker was completely inhibited by the TAP, and there was loss of ventricular contractions and blood pressure. The patient required epicardial A-V pacing to overcome the programmed heart rate of 76 bpm. We describe alternative methods to epicardial pacing. We also recommend close inspection of the chest radiograph, which often can reveal the serial numbers of the implanted pacemaker, as a means of identifying the device’s functions and programming.     

Long-term atrial pacing for sinus node disease with output-terminal programmagle pacemakers.

Long-term transvenous atrial pacing for symptomatic sinus node disease, in the absence of atrioventricular conduction disease, confers the advantages of increased cardiac performance and probable freedom from systemic thromboembolism. Conventional ventricular pacing has been preferred, however, because of the complications of atrial pacing, mainly those of electrical and mechanical instability of currently available atrial electrodes. These complications have been circumvented with a new pacemaker, programmable for output terminal. This has allowed the institution of atrial pacing in seven patients, with its attendant advantages and the ability to reprogram noninvasively to ventricular pacing should atrial pacing fail. Such reprogramming has been accomplished without difficulty in one patient who developed second-degree atrioventricular block and one with electrode microdisplacement.     

Temporary A-V sequential pacing using transluminal pacing electrodes

A case is presented which describes the initiation of atrialventricular (A-V) sequential pacing using atrial epicardial wires and an in situ transluminal ventricular pacing probe. A 68year-old female with a permanent A-V sequential pacemaker was scheduled for elective aortocoronary bypass. Following sternotomy, pacing function was converted to ventricular pacing (WI) with the use of electrocautery. A Chandler® V-pacing probe was introduced through a Paceport® (American Edwards) pulmonary artery catheter and with a paced increase in ventricular rate, the cardiac output increased from 2.8 to 3.2 L · min^-1. At the conclusion of cardiopulmonary bypass the patient was in sinus rhythm at a rate of 67 · min^-1 and was paced to a faster rate using bipolar atrial epicardial wires. The patient subsequently developed intermittent heart block so temporary A-V sequential pacing was established using atrial epicardial wires and the in situ ventricular pacing probe. Pacing was achieved at routine generator output settings of seven milliamps (mA) for both atrium and ventricle and at an A-V interval of 0.120 sec. This resulted in an immediate increase in cardiac output from 3.3 to 4.1L- min^-1. The compatability of these two pacing systems offers an increased margin of safety in cardiac surgery patients requiring atrial pacing, who are at risk for developing postoperative heart block.     

INTRADIALYTIC CARDIAC ARRHYTHMIAS: I

An 87-year-old white male with adult onset diabetes mellitus and progressive renal insufficiency was admitted because of dyspnea. Admission workup revealed a blood urea nitrogen (SUN) of 133 mg/dl, a creatinine of 5.6 mg/dl, a potassium of 5.0 mEq/l, and echocardiographic evidence of a pericardial effusion. The pericardial effusion was not hemodynamically significant, with no pulsus paradoxus and no evidence of right atrial or right ventricular collapse on echocardiogram. Of significance was a past medical history of third degree heart block managed by the placement of a sequential atrial-ventricular (DDD) cardiac pacemaker. On admission his pacemaker was A-V sequential pacing at a rate of 80 bpm .
Hemodialysis was initiated without heparin, and transmembrane pressure was minimized so as not to precipitate cardiac tamponade. No net ultrafiltration occurred during the dialysis. Two hours after the initiation of hemodialysis, hypotension and an irregular tachycardia occurred. The hypotension was not volume responsive. Echocardiogram and rhythm strip showed atrial fibrillation with irregularly irregular ventricular pacing. Cardiology consultation was requested to further evaluate the pacemaker status. The pacemaker was emergently converted to a VVI mode of 90 bpm. The patient subsequently became normotensive and hemodynamically stable. He was also given a loading dose of 1000 mg of procainamide and a continuous infusion of procainamide was initiated at 1 mg/min. Organized atrial activity was restored within 15 min. No further atrial arrhythmias were noted during subsequent hemodialyses .     

Pacemakers—A journey through the years

This is an article on the history of artificial cardiac pacemakers. Before the advent of pacemakers, not much could be done for patients who suffered from cardiac asystole and other cardiac rhythm disturbances. Although the concept that an artificial pacemaker could be used to stimulate the heart in standstill evolved much earlier, it was not until 1952 that the first case of successful pacing of the human heart could be documented. From that time onwards, pacemakers have seen tremendous technological advancements—not only in terms of pacemaker efficacy, but also in terms of patient safety. The outstanding amongst these include the development of myocardial and endocardial electrodes and the invention of a transistorized external pacemaker with a battery backup. With the development of the first implantable pacemaker, the cherished dream of long term pacing came true. At the same time, recognition of pacemaker induced arrhythmias gave an impetus to the evolution of safer modes for cardiac pacing.     

Isoflurane improves the tolerance to pacing-induced myocardial ischemia

Fourteen patients with normal, global, left ventricular function scheduled for elective myocardial revascularization were studied at rest and during atrial pacing before and during isoflurane anesthesia (0.5% end-tidal) plus 50% nitrous oxide. Rapid atrial pacing was performed in a stepwise fashion until the onset of angina pectoris in the awake patients. The same step increase in pacing rate was applied in the anesthetized patients. Compared with prepacing baseline values, isoflurane significantly decreased systemic blood pressure, coronary perfusion pressure, the rate-pressure product, and cardiac index. No patient had ST-segment depression while awake or during isoflurane anesthesia before pacing was started. Prepacing left and right ventricular filling pressures and wave forms were normal, both while awake and during isoflurane anesthesia. The mean pacing rate at which first signs of myocardial ischemia appeared (V5 ST-segment depression greater than or equal to 0.1 mV, increase in pulmonary capillary wedge pressure (PCWP) to greater than or equal to 15 mmHg, and prominent PCWP v-waves greater than or equal to 20 mmHg) was significantly higher during isoflurane anesthesia than in the awake patients (128 +/- 4 vs. 115 +/- 5 beats/min). With the exception of one patient, the individual pacing rates inducing first signs of ischemia in the awake patients were below the anginal threshold. None of the patients had a reduced ischemic threshold during anesthesia. Eleven anesthetized patients tolerated a higher pacing rate until initial signs of ischemia appeared. In four of these patients, the pacing rate required to induce first signs of ischemia was above the heart rate at which chest pain had been induced while they were awake. At a peak atrial pacing rate of 129 +/- 5 beats/min, which had induced angina pectoris in the awake patients, the increase in PCWP was significantly smaller during pacing with isoflurane than during control pacing. Prominent PCWP v-waves (greater than or equal to 20 mmHg) appeared in 12 of the 14 patients during initial pacing to angina and in eight patients paced during isoflurane anesthesia. In six of these eight patients, the abnormal v-waves were less prominent than those observed during control pacing. Ischemic ST-segment changes developed in 13 of 14 patients during initial pacing and in nine patients during pacing with isoflurane. Mean V5 ST-segment depression during the two pacing periods was significantly different, averaging 0.19 and 0.11 mV, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)     

Long-term epicardial ventricular pacing from endocardial bipolar pacemaker lead: perforation of right atrial wall.

One of the hazards of endocardial cardiac pacing is that the pacemaker lead may perforate the myocardial wall or interventricular septum although the incidence of such perforations is believed to be small. This paper describes what is believed to be a unique case in which a pacemaker lead perforated the atrial wall at implantation (or possibly shortly afterwards) and yet gave satisfactory right ventricular epicardial pacing for more than five years. The perforation was discovered during a routine postmortem examination but earlier lateral x-ray examinations would probably have identified the abnormal position of the electrodes. Moreover, the present implantation technique would not have allowed perforation of the atrial wall at implantation to go undetected.     

Single Lead Atrial Synchronous Ventricular Pacing in Japanese Patients with Complete Atrioventricular Block

Abstract: The purpose of this study was to review our experience with atrial synchronous ventricular pacing devices (THERA VDD pacing systems, Medtronic, Inc., U.S.A.) using single atrioventricular leads in Japanese patients with complete atrioventricular block and normal sinus function. Twenty patients with a mean age of 55 ± 13 years underwent implantation of VDD pacemakers. At implantation the amplitude of atrial signals in the supine position during normal breathing, which was measured directly using an external pacing system analyzer, ranged from 1.8 to 5.8 mV with a mean amplitude of 3.4 ± 1.4 mV. Atrial amplitudes did not change during deep breathing (3.3 ± 1.1 mV) or in the semi-Fowler position (3.4 ± 1.6 mV). Atrial oversensing or undersensing was not observed in any of the patients. During a follow-up period, the percentage of atrial synchronization was >95% in 19 patients, and none of the patients had pacemaker related tachycardia or pacemaker related complications. These results were promising enough to warrant the extension of the clinical use of the VDD pacemaker.     

Permanent cardiac pacing in patients on chronic dialysis

Four patients on chronic dialysis, who underwent permanent pacemaker implantation, were reviewed. The indication for pacing was sick sinus syndrome in three patients and complete atrioventricular block in one. Physiological pacing modes were chosen in all patients (DDD in three and AAI in one). Sensing and pacing properties in these patients studied at implantation and at follow-up (22-41 months after implantation) were similar as those in non-dialysis patients. However, the study of these properties during hemodialysis showed a significant elevation of atrial pacing threshold associated with marked decrease of serum potassium concentration in two patients. We conclude that dialysis patients with significant bradyarrhythmia should be considered for pacemaker implantation in the same manner as non-dialysis patients. However, special attention should be payed on the elevation of pacing threshold during hemodialysis.     

Support of cardiac performance following heart valve surgery by raising heart rate to the optimal pacing rate.

Effects of hemodynamic parameters of heart rate were studied in 19 patients with low cardiac output syndrome following open heart surgery for mitral and/or aortic valve replacement in the first five postoperative days. The central venous pressure (CVP), left atrial mean pressure (LAMP), and arterial blood pressures were determined at spontaneous heart rate (SHR), and during graded atrial (12 pts.) or ventricular (7 pts.) pacing each day. An "optimal pacing rate" (OPR), characterized by the most advantageous arterial pressures at the possible lowest levels of CVP and LAMP, and by the suppression of preexisting arrhythmias, if any, was established daily for maintaining each patient on that rate. The SHR was 69 +/- 9 and the OPR was 102 +/- 9 on the first postoperative day. For the fifth postoperative day the SHR was 68 +/- 10 and the OPR decreased to 90 +/- 9. Pacing with the OPR significantly increased cardiac performance. E.g. the hemodynamic improvement on the first postoperative day induced by pacing was comparable to the spontaneous improvement seen during the first five postoperative days. The hemodynamic effect of atrial pacing on circulation was more definitive than that of ventricular pacing. Since OPR may be significantly higher than SHR and varies from day to day, we suggest that, in cases where pacing is applied to improve cardiac performance, it be determined for each patient individually each postoperative day.     

Load dependence of cardiac output in biventricular pacing: right ventricular volume overload in pigs

BACKGROUND: Previous work from our laboratory has demonstrated that optimization of biventricular pacing is load dependent. During acute pulmonary stenosis and right ventricular pressure overload in swine, cardiac output was maximized by pacing the right ventricle 40 ms before the left ventricle. To extend those studies, this experiment examined biventricular pacing optimization during right ventricular volume overload. METHODS: After median sternotomy in 6 anesthetized domestic pigs, complete heart block was induced by ethanol ablation. A conduit was grafted from the right ventricle to the right atrium to simulate tricuspid insufficiency. During epicardial, atrial tracking DDD biventricular pacing, atrioventricular delay was varied between 60 and 180 ms in 30-ms increments. Right ventricular-left ventricular delay was varied at each atrioventricular delay from +80 ms (right ventricle first) to -80 ms (left ventricle first) in 20-ms increments. Aortic flow, right ventricular pressure, and electrocardiogram were measured at each pacemaker setting with the graft clamped and unclamped. RESULTS: Atrioventricular and right ventricular-left ventricular delays had no significant effect on cardiac output with the graft clamped. With the graft unclamped, however, there was a statistically significant (P =.003 by mixed modeling repeated measures analysis of variance) trend toward higher cardiac output with left ventricle-first pacing. CONCLUSION: Left ventricle-first biventricular pacing in swine significantly increased cardiac output during acute tricuspid insufficiency but not during the control state. Trials are warranted to develop clinical biventricular pacing for treatment of perioperative right ventricular dysfunction.     

Effects of bilateral transvenous diaphragm pacing on hemodynamic function in patients after cardiac operations. Experimental and clinical study

The effects of bilateral transvenous diaphragm pacing and intermittent positive-pressure ventilation on hemodynamic function were compared by animal experiment in 18 dogs and by clinical study in 14 patients during the postoperative period after cardiac operations. Aortic, pulmonary arterial, right atrial, and left atrial pressures (transmural) and aortic flow were increased by diaphragm pacing in the canine experiment. In dogs with induced tricuspid insufficiency, aortic pressure, right and left atrial pressures, and aortic blood flow increased, similar to the results obtained in the clinical study. Diaphragm pacing produced a sufficient tidal volume (7.2 to 12 ml/kg) for maintenance of normal blood gas levels in the patients, all of whom recovered spontaneous breathing without any weaning problems after 2 to 6 hours of diaphragm pacing. The catheter electrode used for stimulation was placed 30 mm away from the sinus node to avoid arrhythmias. Respiratory control by diaphragm pacing is hemodynamically superior to that by intermittent positive-pressure ventilation, and its efficacy is expected, especially in critical cases or in diseases or conditions in which the decrease in the load of the right heart affects the hemodynamic status of the patient.     

Interference between a dual-chamber pacemaker and argon electrocautery device during hepatectomy]

We report an unusual electromagnetic interference induced by an argon electrocautery device during a left hepatectomy on a dual chamber pacemaker, implanted for sinus node dysfunction in 87-year-old patient. Argon electrocautery induced inhibition of atrial stimulation and occurrence of irregular ventricular triggered activity. Normal pacemaker function resumed after electrocautery interruption. This case illustrates the need to focus on cardiac rhythm when a new electrical device is used in a pacemaker patient.     

Superselective fibrinolysis for a middle cerebral artery embolism caused by a left atrial myxoma: case report

A case of successful treatment by local fibrinolysis of a middle cerebral artery embolism caused by a thrombus from a left atrial myxoma is reported. A 62-year-old woman using a pacemaker and suffering from sick sinus syndrome was admitted on December 29th 1996, complaining of transient restlessness. CT and cerebral angiography revealed no abnormal vascular lesions. Eighteen months after the initial episode, she suffered a sudden onset of left hemiparesis and loss of consciousness. CT scan performed during the second episode revealed no lesions and, in particular, no early CT infarction sign, but emergent cerebral angiography revealed a right middle cerebral artery embolic occlusion. Local fibrinolysis using a tissue plasminogen activator was performed within 3 hours after the beginning of the episode, and partial recanalization was obtained within one hour after initiation of the fibrinolytic therapy. On the first hospital day, though CT revealed a small low-density area in the right basal ganglia, motor deficits gradually improved. Considering the possibility of a cardiac source of the embolism, trans-esophageal echocardiography was performed and revealed a left atrial tumor suspected to be a myxoma. It was removed by surgery on the 34th hospital day. Histological examination proved it to be a myxoma. Nine months after local fibrinolytic therapy, the patient returned to work. The diagnosis of cerebral embolism caused by cardiac myxoma is difficult to make at the time when the patient is first examined after admission. It is also hard to discover during emergent cerebral angiography with fibrinolytic therapy. Therefore, in the case of patients with cerebral embolism for which local fibrinolysis is ineffective, it should be presumed that cardiac myxoma is the source of the embolus. Direct PTA alone may be effective for such tumoral embolism.     

Tempor?re Schrittmachertherapie bei herzchirurgischen Operationen

Bradycardia during and after cardiac surgery requiring temporary pacing is observed in roughly 50% of patients. Complete heart block as well as bradycardia associated with a sinus node dysfunction or permanent atrial fibrillation are the most common types of perioperative bradycardia; however, in some cases even a heart rate below 80 beats/min can be associated with hemodynamic problems. Finally, the occurrence of bradycardia in the immediate postoperative period after cardiac surgery cannot be predicted with reasonable accuracy. Thus, implantation of temporary epimyocardial stimulation leads in every patient undergoing cardiac surgery is common practice. The versatility of temporary pacing in cardiac surgery is unique, as all parts of the heart can be accessed during the operation. Thereby it allows temporary atrial, AV-sequential, P-wave synchronized or biventricular pacing in addition to ventricular pacing, the only pacing mode available for temporary pacing outside cardiac surgery. This results in desirable and substantial hemodynamic advantages compared to single chamber ventricular pacing for cardiac surgery patients in the perioperative period. This article summarizes the key elements of temporary pacing after cardiac surgery and adds some practical points.     

Temporary cardiac pacing for fatal arrhythmia in living-donor liver transplantation: three case reports

Cardiac pacing often turns out to be the only effective treatment of severe, life-threatening arrhythmias. We performed 77 living-donor liver transplantations (LDLT) from 1999 to 2007. In these cases, three recipients experienced fatal arrhythmia and required temporary cardiac pacing during the perioperative period. The first case was a 68-year-old woman diagnosed with liver cirrhosis and hepatocellular carcinoma (HCC). Her Model for End-Stage Liver Disease (MELD) score was 34. We performed LDLT using a right lobe graft. She showed complete atrioventricular block with cardiac arrest at postoperative day (POD) 42 after a bacterial infection. We performed a resuscitation and instituted temporary cardiac pacing. However, she was dead at POD 43. Pathologic findings at autopsy showed a diffuse myocardial abscess, which caused the fatal arrhythmia. The second case was a 58-year-old man diagnosed with HCC and liver cirrhosis; his MELD score was 9. We performed LDLT using a right lobe graft. He showed atrial fibrillation after septic shock. He also showed sinus bradycardia with a cardiac arrest at POD 10. We performed resuscitation and emergent temporary pacing. He recovered and was alive without recurrence of arrhythmia or infection. The third case was a 58-year-old woman diagnosed with multiple HCC. During preoperative regular check-up, she was diagnosed to have cardiac hypertrophy and was started on beta-blockers as treatment for cardiac hypertrophy. However, severe bradycardia necessitated temporary cardiac pacing. LDLT was performed safely after implantation of a pacemaker. Early use of temporary cardiac pacing for severe arrhythmias may be effective to maintain the hemodynamic state in LDLT.     

Transvenous permanent pacemaker implantation for Fabry's disease. 3 cases report

Three men with Fabry's disease (angiokeratoma corporis diffusum universal ) are described. In the first patient, atrial fibrillation appeared, and a permanent cardiac pacemaker (VVI) was implanted. Sick sinus syndrome with complete atrioventricular block was occurred on the second patient. Transvenous pacemaker (DDD) implantation was performed for him. The last patient was younger brother of the second patient. He demonstrated complete atrio-ventricular block, so cardiac pace maker (VAT) was implanted. They showed a low value of granulocyte's alpha-galactosidase activity. During 1 to 4 year follow up period, they showed no trouble about pacemaking. Fabry's disease is an disorder of glycosphingolipid metabolism. This disorder is characterized by the accumulation of trihexosyl ceramide in many sites. Cardiac involvement and abnormal electrocardiographic manifestations are common in this disorder. Permanent cardiac pacemaker is necessary for severe bradycardia caused by this disorder.     

Surgical treatment for right ventricular perforation caused by transvenous pacing electrodes: A report of three cases

We experienced three cases of right ventricular perforation that were induced by transvenous pacing electrodes. The patients were a 72-year-old man who underwent percutaneous transluminal coronary recanalization and angioplasty, an 80-year-old woman who had temporary transvenous pacing for a complete atrioventricular block induced by acute valvular heart failure, and a 44-year-old man who had received a permanent pacemaker. All three patients were treated surgically. The first and second patients demonstrated either cardiac tamponade or hemopericardium necessitating pericardial drainage. Spontaneous hemostasis did not occur in cases 1 and 2, due to either anticoagulant therapy or myocardial degeneration. Such patients require surgical closure of the perforation and pericardial drainage as soon as pericardial effusion is confirmed. In contrast, middle-aged individuals without myocardial damage, such as patient 3, need only a simple removal and repositioning of the electrode followed by serial echocardiography.