Bradycardia-Tachycardia Syndrome Due to Sinus Node Disease and Concealed Wolff-Parkinson-White Syndrome

A 75-year-old woman was admitted to the hospital because of a supraventricular tachycardia, long sinus pauses and ventricular tachycardia of the torsades de pointe type. Temporary ventricular pacing suppressed ventricular arrhythmias but supraventricular tachycardia persisted. An electrophysiologic study revealed the coexistence of sick sinus syndrome and circus movement tachycardia due to a concealed left-sided accessory atrioventricular pathway. This case represents a previously undescribed form of the bradycardia-tachycardia syndrome.     

DDI Pacing: Indications, Expectations, and Follow-Up

The DDI mode of pacing that permits noncompetitive atrioventricular sequential bradycardia support was chosen in 65 of 480 (14%) patients selected for dual chamber pacing between February 1985 and March 1990. All patients were implanted with Pacesetter 283 or 285 pulse generators and programmed to DDI. The indications for pacing were sick sinus syndrome (n = 52), combined sinus node dysfunction and AV block (n = 13). Forty-two of these patients had a history of paroxysmal atrial arrhythmias. All patients received passive fixation atrial and ventricular leads. Follow-up thereafter was performed predischarge, and at 6 weeks, 3 and 6 months after discharge. The duration of follow-up ranged from 1-61 months (mean 31 months). Fifty-four of 65 (83%) patients chosen for DDI remain programmed in the DDI mode. Three patients were reprogrammed to VVI and eight to DDD. During the course of follow-up, six patients presented with effective VVI pacing with consistent ventriculoatrial conduction that was appropriately sensed by the atrial circuit with atrial output inhibition. A further four patients presented with "functional undersensing" due to ventricular blanking period (VBP) characteristics in these pulse generators and in this mode. Functional undersensing was eliminated in all but one patient by reprogramming the VBP to 13 msec with no subsequent episodes of provoked crosstalk inhibition. Effective VVI pacing was observed in patients with AV block during times of sinus acceleration. While DDI mode is an effective form of pacing, permitting non-competitive atrioventricular sequential pacing, potential limitations include: effective VVI pacing during intact ventriculoatrial conduction, functional undersensing when long VBP are programmed, and effective VI pacing with sinus node acceleration during AV block.     

Validation of a Method for Choice of Pacing Mode in Carotid Sinus Syndrome With or Without Sinus Bradycardia

A new method for selection of the pacing mode in 60 consecutive patients with severe cardie-inhibitory or mixed carotid sinus syndrome was prospectively validated. ODD pacing was preferred for 26 patients with: (1) the cardioinhibitory form and who had symptomatic pacemaker effect; (2) mixed type I form, (cardioinhibitory and vasodepressor) with symptomatic pacemaker effect, ventriculoatrial conduction or orthostatic hypotension; (3) mixed type II; or (4) severe bradycardia. VVI pacing was seiected in the remaining 34 patients without these symptoms. During a 32 ± 10 month follow-up period syncope and severe dizziness persisted in five patients in the VVI group (15%) and in three patients in the ODD group (12%). Symptomatic relief occurred in 87% (52/60) of patients. Minor symptoms persisted in 47% of the VVI group and 42% of the DDD group. No patient developed cardiac insufficiency or intolerance to pacing. During a 2-month duration a single-blind, randomized, cross-over study compared VVI and DDD pacing, 69% of the patients programmed from DDD to VVI suffered more frequent, severe, and intolerable symptoms. (1) Thirty four of 60 patients (57% of the entire group) in whom VVI pacing was satisfactory were identified prior to pacemaker implant. In the remainder, VVI pacing was contraindicated as it produced frequent side effects. (2) The preimplant predictive value that VVI pacing would be successful was 85% for those eventually receiving VVI pacemakers and the preimplant predictive value that VVI pacing would fail was 69% for those who underwent DDD implant.     

Pacing for Carotid Sinus Syndrome and Sick Sinus Syndrome

BRIGNOLE, M., ET AL: Pacing for Carotid Sinus Syndrome and Sick Sinus Syndrome. The real incidence of pacemaker implants for carotid sinus syndrome (CSS) and the relation between CSS and sick sinus syndrome (SSS) is not precisely known. Patients who needed pacing therapy because of atrial bradyarrhythmias were investigated by means of carotid sinus massage, dynamic ECG, and invasive electrophysiological sinus node evaluation. Of 298 consecutive patients receiving a pacemaker implant, 36 (12%) had a severe cardioinhibitory carotid sinus reflex with reproducible spontaneous symptoms (CSS), 33 (11%) had sinus bradycardia < 50 beat/min or an abnormal electrophysiological evaluation (SSS) and 24 (8%) had both (CSS + SSS). The annual incidence was 40, 37, and 26, respectively, implants per year/million of inhabitants (total incidence 325). Patients affected by CSS, if compared with those affected by SSS, showed: a higher prevalence of syncope (97% vs 42%); more syncopal, episodes per patient (2.9 ± 2 vs 1.8 ± 0.9); a lower prevalence of associated cardiac diseases (53% vs 100%); cardiac enlargement (36% vs 88%); heart failure (6% vs 36%) and paroxysmal atrial fibrillation (0% vs 42%); and a more frequent indication for VVI pacing (75% vs 3%). In patients with CSS + SSS, intermediate characteristics were present. In conclusion, CSS is as frequent an indication to cardiac pacing as SSS; clinical differences justify a distinction between them, even if they are associated in 26% of cases.     

A New Dual-Chamber Pacing Mode to Minimize Ventricular Pacing

Despite the low long-term incidence of high-degree atrioventricular (AV) block and the known negative effects of ventricular pacing, programming of the AAI mode in patients with sinus node dysfunction (SND) remains exceptional. A new pacing mode was, therefore, designed to combine the advantages of AAI with the safety of DDD pacing. AAIsafeR behaves like the AAI mode in absence of AV block. First- and second-degree AV blocks are tolerated up to a predetermined, programmable limit, and conversion to DDD takes place in case of high-degree AV block. From DDD, the device may switch back to AAI, provided AV conduction has returned. The safety of AAIsafeR was examined in 43 recipients (70 ± 12-year old, 24 men) of dual chamber pacemakers implanted for SND or paroxysmal AV block. All patients underwent 24-hour ambulatory electrocardiographic recordings before hospital discharge and at 1 month of follow-up with the AAIsafeR mode activated. No AAIsafeR-related adverse event was observed. At 1 month, the device was functioning in AAIsafeR in 28 patients (65%), and the mean rate of ventricular pacing was 0.2%± 0.4%. Appropriate switches to DDD occurred in 15 patients (35%) for frequent, unexpected AV block. AAIsafeR mode was safe and preserved ventricular function during paroxysmal AV block, while maintaining a very low rate of ventricular pacing. The performance of this new pacing mode in the prevention of atrial fibrillation will be examined in a large, controlled study.     

Reliability of Transesophageal Pacing in the Assessment of Sinus Node Function in Patients with Sick Sinus Syndrome

The purpose of this study was to find out whether transesophageal pacing could be utilized for assessment of sinus node function in patients with sick sinus syndrome (SSS). In 17 patients with SSS (study group) we compared the results of sinus node tests obtained both in the basal state and after pharmacological autonomic blockade by endocavitary stimulation and, 24 hours later, by transesophageal pacing. In another group of 17 patients with SSS (control group), we compared the results obtained by two endocavitary studies. In "study group", sinus cycle length (SCL) and corrected sinus node recovery time (CSRT) did not show significant differences between the two studies both in the basal state and after autonomic blockade, whereas sinoatrial conduction time (SACT) was more prolonged during esophageal pacing (P less than 0.01). In "control group", sinus node measures did not show significant differences between the two studies. In the "study group," the following coefficients of correlation were obtained in the basal state; SCL, r = 0.65, CSRT, r = 0.57, SACT, r = 0.52 and after autonomic blockade: SCL, r = 0.95, CSRT, r = 0.62 and SACT, r = 0.53. In the basal state, the correlation for SCL and CSRT between the two studies was lower in the "study group" than in the "control group" (P less than 0.05), whereas after autonomic blockade the correlation for sinus node measures did not show significant differences between the two groups of patients. These data suggest that transesophageal study influences the autonomic tone regulating the sinus node; however, it is not responsible for important variations in sinus node measures.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prevention of Intra-Atrial Reentry by Chronic Atrial Pacing

The authors describe a cose of so-called "intra-atrial reentry," associoted with sinus node dysfunction. The spontaneous initiation of the tachycardia was always preceded by a sinus pause, and external atrial pacing prevented the appearance of tachycardia. Thus an atrial pacemaker was implanted, and after several months, the atriaJ dysrhythmias disappeared completely, despite interruption of the antiarrhythmic drugs. When a pacemaker dysfunction occurred, the sinus node dysfunction and the tachycardia reappeared. This is analogous with the "incessant" tachycardias seen in the WPW syndrome, and must be differentiated from the usual forms of the sick sinus syndrome which require both a pacemaker and antiarrhythmic drugs.     

Intermittent Pacemaker Syndrome: Revision of VVI Pacemaker to a New Cardiac Pacing Mode for Tachy-Brady Syndrome

A patient with tachy-brady syndrome manifested by paroxysmal atrial fibrillation and symptomatic sinus bradycardia and treated by VVI pacing developed pacemaker syndrome during episodes of ventricular pacing. His cardiac pacemaker was revised to a dual chamber system utilizing the new AV sequential DDI pacing mode which eliminated pacemaker-related tachycardias and totally abolished the pacemaker syndrome symptoms. There have been no further episodes of atrial fibrillation, possibly due to elimination of temporal dispersion of refractory periods during bradycardia. The propensity for atrial fibrillation has also been minimized by excluding competitive atrial stimulation during DVI pacing. The DDI mode provides the clinician increased utility and flexibility in the use of AV sequential pacing therapy.     

Thyrotoxicosis Induced Sick Sinus Syndrome: Medical Therapy May Avoid Permanent Pacing

A 65-year-old white female developed sick sinus syndrome associated with thyrotoxicosis which resolved upon achieving a euthyroid state, thus obviating the need for permanent pacemaker implantation. TSH was less than 0.1 ng/dL, and 24-hour iodine uptake was 28%. After correction of the hyperthyroid state with propylthiouracil and potassium iodine, sinoatrial pauses up to 6 seconds resolved over 10 days. A subsequent sinus node recovery time was normal and no symptoms recurred over 22 months.     

The Role of Rate Hysteresis Pacing in the Hypersensitive Carotid Sinus Syndrome

The ability of rate hysteresis programming with the escape interval longer than the automatic interval lo reduce the hypotensive response to carotid sinus massage at the onset of ventricular pacing was studied in six patients paced for carotid sinus syndrome. Rate hysteresis significantly reduced this hypotensive response and abolished spontaneous symptoms in two patients and symptoms reproduced by carotid sinus massage in four patients.     

The Role of Rate Hysteresis Pacing in the Hypersensitive Carotid Sinus Syndrome

The ability of rate hysteresis programming with the escape interval longer than the automatic interval lo reduce the hypotensive response to carotid sinus massage at the onset of ventricular pacing was studied in six patients paced for carotid sinus syndrome. Rate hysteresis significantly reduced this hypotensive response and abolished spontaneous symptoms in two patients and symptoms reproduced by carotid sinus massage in four patients.     

Permanent Atrial Pacing in Cardiac Transplant Patients

Thirteen out of 223 consecutive cardiac transplant patients required permanent pacemaker implantation; 11 for sinus node dysfunction and 2 for complete AV block. Patients with sinus node dysfunction were considered for AAIB mode pacemakers if they had intact AV conduction defined as a Wenckebach point of > 120 beats/min. Ten of 11 patients with sinus node dysfunction had a single atrial lead placed. Atrial lead placement was most easily accomplished with a straight, active fixation lead and the use of manually curved stylets to find an optimal position in the donor atrium, although active fixation leads with a preformed atrial J were used as well. Two leads dislodged requiring revision. In contrast, only 1 of 250 atrial leads implanted in nontranspianted hearts dislodged (P < 0.0001). Transvenous endomyocardial biopsies have not caused atrial lead dislodgment. Most transplant recipients requiring permanent pacing have intact AV nodal function and require only atrial pacing. Atrial lead dislodgment requiring lead revision occurs more frequently in heart transplant recipients than in native hearts. Use of a straight active fixation lead with a munually formed curve in the stylet is useful in order to find the optimal position for pacing.     

Long-Term Pacing in Heart Transplant Recipients is Usually Unnecessary

The indications for and timing of permanent pacing were reviewed in all 17 of 154 adult heart transplant recipients at this center who have had permanent pacemakers implanted. Resting 12-lead ECGs recorded during routine follow-up were examined. A prospective study of pacing requirement was then undertaken. Holter monitoring was performed before and after reprogramming the pacemakers to VVI mode at 50 beats/min. Exercise responses in various pacing modes were then assessed in seven patients with rate responsive pacemakers using a standard Bruce protocol treadmill test. The indication for pacing was sinus node dysfunction in 59% (10/17) and atrioventricular (AV) block in 41% (7/17). The majority of pacemakers were implanted between seven and 21 days after transplantation. There was a progressive reduction in the frequency of pacing on 12-Jead ECGs with time after transplantation. Eight of 14 patients with empirically selected programming paced during Holter monitoring. After reprogramming to 50 beats/ min VVI mode only three of 14 patients, all with sinus node dysfunction, paced. Rate responsive pacing made no difference to exercise time. The requirement for long-term pacing in cardiac transplant recipients is small (3/154) and is limited lo patients with sinus node dysfunction. Rate responsive pacing did not increase exercise tolerance.     

Anomalous "VVI" Pacing of a Dual Chamber Pacemaker When Programmed in DDI(R) Mode

We describe the case of a dual chamber rate responsive pacemaker (Relay, model 294-03, Intermedics, Angleton, TX, USA) implanted in a 68-year-old male for sick sinus syndrome, which was not working properly when programmed in the DDIR mode, thus determining occasionally a sort of "VVI" pacing. However, the pacemaker performed well when programmed in the DDDR mode. We discovered that this was not a malfunction of a single device but rather a general behavior of this family of Intermedics dual chamber pacemakers (also not rate responsive), caused by a software problem.     

Inappropriate Ventricular Blanking in a DDI Pacemaker

The DDI mode is a new pacing mode with potential advantages over DVI pacing. We describe anomalous post R wave ventricular pacing due to the presence of inappropriate ventricular blanking periods in a pacemaker programmed to the DDI mode. Although no adverse consequences were seen in our patients, potentially dangerous R-on-T pacing could occur, particularly if long atrioventricular delays are programmed. A method for eliminating this pacing anomaly is described. Patients programmed to the DDI mode with the pacemaker model described should be evaluated for post R wave ventricular pacing and corrective measures should be taken.     

Incidence and Predictors of Loss of Pacing in the Atrium in Patients with Sick Sinus Syndrome

Atrial and dual-chamber pacemakers may be associated with reduced morbidity in patients with the sick sinus syndrome (SSS). In some patients, however, subsequent development of chronic atrial fibrillation or atrial lead failure make long-term pacing in the atrium not feasible. We analyzed the incidence and predictors of loss of atrial pacing in 395 consecutive patients with SSS (376 with dual-chamber pacemakers and 19 with single-chamber atrial pacemakers). None of them was in established atrial fibrillation at time of implant. Patients were followed-up for 55 ± 35 months. Actuarial survival of effective atrial pacing was 92.5% at 1 year, 85% at 5 years, and 76.5% at 10 years. Overall, 60 patients lost atrial pacing. The most frequent cause was the development of chronic atrial fibrillation (53 patients). By multivariate analysis (Cox proportional-hazards model), independent predictors of Joss of pacing in the atrium were preimplant episodes of paroxysmal atrial fibrillation (PAF) lasting more than 1 hour (P < 0.001; hazard ratio (HR) = 4.3); prior history of PAF for more than 5 years (P < 0.001; HR = 2.67; and endocardial P wave < 2 mV (P = 0.014; HR = 1.96). In a subgroup of patients (n = 187) who had echocardiograms, a left atrium > 50 mm was also an independent predictor of loss of atrial pacing (P = 0.028; HR = 2.28). Conclusions: 1) most patients with SSS can maintain long-term atrial pacing; 2) loss of pacing in the atrium is related to the previous history of PAF, left atrial enlargement, and low amplitude of the endocardial P wave at implant; and 3) patients with these risks variables are less than ideal candidates for atrial pacing modes. In them, the implant of DDDR units might be indicated, to provide wide flexibility in case reprogramming to a ventricular pacing mode is required.     

Pacing of the Atria in Sick Sinus Syndrome Trial: Preventive Strategies for Atrial Fibrillation

SPITZER, S.G., et al .: Pacing of the Atria in Sick Sinus Syndrome Trial: Preventive Strategies for Atrial Fibrillation. This study examines the effects of various atrial lead positions in physiological pacing on the incidence of AF in patients with sick sinus syndrome. The lead is implanted in the RA free wall, in the RA appendage, near the coronary sinus ostium (CSO) or, in dual site RA pacing, in the appendage and the CSO. Since CSO and dual site right atrial pacing aim at modifying the pathological substrate, pacing of two-thirds of all cardiac cycles is attempted by adapting the basic rate and the rate response option. The results of this study are expected to assist in the development of guidelines for the placement of atrial pacing leads in sick sinus syndrome. (PACE 2003; 26[Pt. II]:268–271)     

Is Chronic Atrial Stimulation a Reliable Method for Single Chamber Pacing in Sick Sinus Syndrome?

To evaluate the feasibility of chronic atrial pacing (AAI) in sick sinus syndrome (SSS), 22 patients (pts) with bradytachycardia syndrome (BTS) and 17 patients with only bradyarrhythmias (BA) were studied on the incidence of supraventricular tachycardias (SVT) and occurring AV block. A scoring system based on symptoms of SVT was developed (grade 0–5). All patients had proven normal AV conduction before PM implantation. In the BTS-group, nine patients (41%) had symptomatic SVT at the end of follow-up (mean 53 months), despite drug therapy. These patients had a high SVT score on entry (mean 3.2). High degree AV block occurred in three patients. Although in the BA-group SVT arose in six patients (35%), there was only one symptomatic patient at the end of follow-up (mean 36 months). In this group, only one patient developed high degree AV block. Atrial stimulation should be considered as a reliable therapy in patients with SSS and low SVT score before PM implantation when normal AV conduction is present.     

Carotid Sinus Syndrome: Acute Hemodynamic Evaluation of a Dual Chamber Pacing Mode

Cardiac pacing is the treatment of choice in patients with carotid sinus syndrome (CSS), Three different pacing modes were tested in 20 patients (16 males, 4 females; mean age 75 ± 9 years) with documented symptomatic CSS, Three carotid sinus massages (CSM) were performed in each supine patient successively paced in random order in: DDI—the reference pacing mode; DDD—automatic mode conversion (DDD/AMC) allowing automatic switching from AAI to DDD when AV block occurs; DDD/AMC plus a trial acceleration (DDD/AMC + ace); and OOO (CSM without pacing) to determine whether the vasodepressive effect was still present 10 minutes after the preceding CSM. Intraarterial blood pressure was continuously monitored. Results were expressed as the value of the mean systolic BP at TO + 3 s + 6 s … TO + 30 s divided by the value of the mean systolic blood pressure prior to onset of CSM. The drop in arterial blood pressure was more severe in the DDI mode than in DDD/AMC (P < 0,001) and DDD/AMC + acc (P < 0.0001) in 20 patients. In the OOO mode, the drop in arterial blood pressure was most marked and greater than in the DDI mode (P < 0.0001). The average time between start of the CSM and onset of the drop in blood pressure was the same in the three dual chamber modes. We conclude that the DDD/AMC mode significantly improves the vasodepressor response to CSM compared to the DDI mode. There is a current trend favoring DDD/AMC + acc over DDD/AMC.