Three-year follow-up of atrial sensing efficacy in children and adults with a single lead VDD pacing system.

The purpose of this study was to evaluate the efficacy of atrial sensing in children with a single pass lead VDD pacing system and to compare it with the efficacy of atrial sensing in adult patients with the same pacing system. Although the feasibility of single pass lead VDD pacing system implantation in children was recently demonstrated, the efficacy of atrial sensing remains unclear. In addition, the effect of accelerated growth of children on the systems' efficacy has not been addressed. Atrial sensing followed by ventricular sensing and atrial sensing followed by ventricular pacing was prospectively evaluated in 13 children (age 0.5-15 years) and 24 adult patients (age 19-74 years). All had the same endocardial pacing system using a single pass lead. The children and adults had effective atrial sensing at a success rate of 94.00 +/- 9.687% and 96.04 +/- 4.64%, respectively, during mean follow-up of 3.5 years. The atrial electrogram amplitude was similar in both groups, 1.8 +/- 1.5 mV in children and 1.8 +/- 1.1 mV in adults. The adult patients more frequently exhibited ventricular sensing following atrial sensing. The ventricular pacing threshold and impedance were stable in both groups. When necessary, in children, the atrial sensing was corrected by adjusting the pacemaker's lower rate programming. Highly effective atrial sensing was demonstrated in children and adult patients with a single pass lead VDD pacing system. During a mean follow-up of 3.5 years, not only was the atrial electrogram amplitude stable, but the clinically relevant atrial sensing was highly effective, justifying endocardial pacing with single pass lead VDD pacing in children and adults with preserved sinus node function.

The role of the psychiatrist as medical director: a survey of psychiatric administrators.

Previous surveys of public and community psychiatrists have demonstrated that medical directors perform a wider variety of tasks, and experience increased job satisfaction, compared to staff psychiatrists. Notwithstanding respondents' belief that clinical collaboration tasks contribute most to job satisfaction, the performance of administrative tasks is most highly correlated with overall job satisfaction. The current survey was undertaken to determine whether these findings could be replicated among hospital-based psychiatrists. Demographic and job characteristic profiles of hospital-based psychiatrists were clearly distinguished from those of community psychiatrists. Despite these differences, task profiles and job satisfaction parameters of hospital-based psychiatrists were comparable to those previously reported for community psychiatrists.

Transvenous pacemaker leads do not worsen tricuspid regurgitation: a prospective echocardiographic study.

Limited prospective data are available regarding the influence of pacemaker leads on tricuspid valve function. To examine the true incidence of these complications, 35 patients were prospectively examined by two-dimensional and Doppler echocardiography before and after implantation of either a permanent pacemaker or an automatic implantable cardioverter-defibrillator. Of the 35 patients imaged preoperatively, the amount of tricuspid regurgitation (TR) was judged as normal or trivial in 15 (43%), mild in 10 (29%), moderate in 8 (23%), and severe in 2 (6%). Following electrode implantation, TR was noted to be normal or trivial in 13 (38%), mild in 15 (48%), moderate in 6 (17%) and severe in 1 (3%). We conclude that implantation of permanent right ventricular electrodes is not usually associated with an acute worsening of tricuspid regurgitation in most patients.

Artifacts recorded through failing bipolar polyurethane insulated permanent pacing leads.

Pacing failure in bipolar systems using polyurethane insulated leads may be frequent depending on the type of polyurethane and can cause oversensing and or failure to capture. The reason for this failure is often breakage in the inner insulation. The aim of this study was to evaluate the signals created by such a short circuit. Thirty-seven patients were included in the study, 13 with failing leads with polyurethane 80A insulation, 14 with old but normally functioning leads and 10 patients with new leads. Artifacts in the form of spikes were recorded, during surgical revision, from 11 patients with failing leads (84.6%). In patients with normally functioning leads and newly implanted leads no artifacts were recorded. A significant decrease in impedance of 373.4 Ohms (99% confidence intervals 286.4-460.4, P<0.05) was noted in the failing leads compared with a decrease of only 113.0 Ohms (99%, confidence intervals 6.5-219.6, P<0.01) in the control leads. The difference between the groups was highly significant. In 10 newly implanted and five normally functioning bipolar ventricular leads similar artifacts could be created by making intermittent contact between the proximal lead connections. Thus, artifacts could be recorded from failing leads and from intact leads with artificial intermittent connection at the proximal end. Our results suggest that the failure is caused by a short circuit in the lead. This finding may have important clinical applications in the follow-up of bipolar pacing and defibrillation leads.

Rpb4, a subunit of RNA polymerase II, enables the enzyme to transcribe at temperature extremes in vitro.

Rpb4 is a subunit of Saccharomyces cerevisiae RNA polymerase II (Pol II). It associates with the polymerase preferentially in stationary phase and is essential for some stress responses. Using the promoter-independent initiation and chain elongation assay, we monitored Pol II enzymatic activity in cell extracts. We show here that Rpb4 is required for the polymerase activity at temperature extremes (10 and 35 degreesC). In contrast, at moderate temperature (23 degreesC) Pol II activity is independent of Rpb4. These results are consistent with the role previously attributed to Rpb4 as a subunit whose association with Pol II helps Pol II to transcribe during extreme temperatures. The enzymatic inactivation of Pol II lacking Rpb4 at the nonoptimal temperature was prevented by the addition of recombinant Rpb4 produced in Escherichia coli prior to the in vitro reaction assay. This finding suggests that modification of Rpb4 is not required for its functional association with the other Pol II subunits. Sucrose gradient and immunoprecipitation experiments demonstrated that Rpb4 is present in the cell in excess over the Pol II complex during all growth phases. Nevertheless, the rescue of Pol II activity at the nonoptimal temperature by Rpb4 is possible only when cell extracts are obtained from postlogarithmic cells, not from logarithmically growing cells. This result suggests that Pol II molecules should be modified in order to recruit Rpb4; the portion of the modified Pol II molecules is small during logarithmic phase and becomes predominant in stationary phase.

Two-year follow-up in pediatric and adult patients with single-pass lead VDD pacing system.

VDD pacing follow-up is similar in pediatric and adult patients. Atrial and ventricular pacing parameters are stable during 2-year follow-up in children, and single-pass lead VDD pacing is recommended when the sinus node function is normal.

Signal-averaged P wave in patients with paroxysmal atrial fibrillation.

The theoretical and experimental rational of atrial signal-averaged ECG in patients with AF is delay in the intra-atrial and interatrial conduction. Similar to the ventricular signal-averaged ECG, the atrial signal-averaged ECG is an averaging of a high number of consecutive P waves that match the template created earlier P wave triggering is preferred over QRS triggering because of more accurate aligning. However, the small amplitude of the atrial ECG and its gradual increase from the isoelectric line may create difficulties in defining the start point if P wave triggering is used. Studies using P wave triggering and those using QRS triggering demonstrate a prolonged P wave duration in patients with paroxysmal AF. The negative predictive value of this test is relatively high at 60%-80%. The positive predictive value of atrial signal-averaged ECGs in predicting the risk of AF is considerably lower than the negative predictive value. All the data accumulated prospectively on the predictive value of P wave signal-averaging was determined only in patients undergoing coronary bypass surgery or following MI; its value in other patients with paroxysmal AF is still not determined. The clinical role of frequency-domain analysis (alone or added to time-domain analysis) remains undefined. Because of this limited knowledge on the predictive value of P wave signal-averaging, it is still not clinical medicine, and further research is needed before atrial signal-averaged ECG will be part of clinical testing.

Single pass lead VDD pacing in children and adolescents.

Implantation of permanent pacemakers in children and adolescents is possible but usually is limited to single chamber generators. The natural growth of these patients may require physiological pacing, but until recently two leads were required for this type of pacing. The single pass lead VDD pacing mode makes possible physiological pacing by using only one lead, for both atrial sensing and ventricular sensing and pacing. The feasibility of VDD pacing using endocardial lead was evaluated in 16 children and adolescents with congenital or postsurgical atrioventricular block. Their mean age was 7.9 +/- 4.9 years (range 1-16 years) and the smallest patient's weight was 8.2 kg. In all the patients, a single pass pacing lead with atrial sensing rings and bipolar ventricular pacing and sensing capability was implanted through the left or right subclavian vein. The pacemaker generator was implanted in a rectopectoral position. The mean atrial electrogram during the implantation was 4.2 +/- 2.1 mV and 2.6 +/- 1.9 mV after a mean of 1 week. The ventricular pacing threshold was 0.5 +/- 0.2 V; the ventricular pacing impedance was 560 +/- 95 omega; and the ventricular electrogram amplitude was 9.9 +/- 2.1 mV. This is a first report to demonstrate the feasibility of atrial synchronous ventricular endocardial pacing using a single pass lead in a relatively large group of children and adolescents.

Coronary angiographic characteristics of patients with permanent artificial pacemakers.

BACKGROUND: The cause of severe cardiac conduction disturbances is often uncertain. The aim of this study was to examine a group of patients with permanent pacemakers who underwent coronary arteriography to determine the extent of coronary atherosclerotic disease that might be responsible for the conduction disturbances. METHODS AND RESULTS: Forty-three consecutive patients with a permanent pacemaker and 36 matched control patients were investigated. The coronary angiographic study included measurement of diameter and stenosis severity, qualitative assessment of flow, and classification of pathological anatomy, particularly the blood supply to territories supplying the different segments of the conduction system. Among 43 patients with a permanent pacemaker, 27 had ischemic heart disease (17 after coronary artery bypass graft surgery). The conduction disturbance was infranodal in 28 patients, sinus nodal in 6, AV nodal in 4, and complete AV block of unspecified origin in 5. Patients with permanent pacemakers had a coronary artery pathology compromising blood flow to the septal branches and the right coronary artery (type IV anatomy). This pattern was significantly different from the matched control patients, in whom the most prevalent coronary anatomy was the combination of right coronary artery with distal left anterior descending artery (not involving the septal branches) lesions (P=.007). CONCLUSIONS: Patients with coronary artery disease and severe conduction disturbances that require implantation of permanent pacemakers are more likely to have a specific pathological coronary anatomy that combines a compromised blood flow to the septal branches of the left anterior descending artery with right coronary artery lesions. The location of lesions in the coronary tree rather than severe diffuse atherosclerosis appears to be responsible for the conduction disturbances.

The psychiatrist's role as medical director: task distributions and job satisfaction.

OBJECTIVES: Previous surveys of the alumni of Columbia University's fellowship in public psychiatry suggest that a large number of alumni fill positions as program medical directors. In contrast with agency medical directors, program medical directors work within team structures and maintain a high degree of clinical involvement. The fellowship faculty surveyed the alumni to catalog the tasks performed by program medical directors, agency medical directors, and staff psychiatrists and to determine the extent to which these tasks contribute to job satisfaction. METHODS: A survey form was developed using a list of tasks derived from the American Psychiatric Association's guidelines for psychiatrists working in organized mental health care delivery systems and from a recent article that surveyed job descriptions of psychiatrists in community mental health centers. The survey form was distributed to all current fellows and alumni in active practice (N = 89). RESULTS AND CONCLUSIONS: Seventy-two forms were returned, for a response rate of 81 percent. Respondents who were medical directors performed a greater variety of tasks and reported higher job satisfaction than those who were staff psychiatrists. Higher job satisfaction was related to a greater variety of tasks performed, especially tasks involving clinical collaboration. Most of the respondents were program medical directors rather than agency medical directors. The position of program medical director constitutes a relatively small and attainable step above that of staff psychiatrist. Agencies would do well to consider creating positions of program medical directors for their staff psychiatrists whenever feasible, and psychiatrists committed to public-sector careers should negotiate to have such positions.

The ongoing influence of staff training on the performance of radiofrequency catheter ablation.

The aim of this study was to assess whether the performance of RF catheter ablations continues to improve by further staff training once an initial success rate of > 90% has been achieved. Two hundred and ninety-five procedures of SVT catheter ablation using RF energy were studied. Atrial tachycardia and atrial flutter substrate ablations were not included. The procedures were performed during a 4-year period by the same physician and nurse, who had previous training in these procedures. The 4-year period was subdivided into four consecutive 1-year periods in which 69, 72, 68, and 86 procedures were performed. The outcome, recurrence rate, and duration of the curative procedure were compared among the four periods. There was no significant difference in the initial success rate among the four periods. The recurrence rate decreased from 21.74% to 13.95% (P < 0.05). The duration of the curative procedure decreased from 93.7 +/- 78.4 minutes to 39.1 +/- 32.2 minutes (P < 0.001), and the fluoroscopic time decreased from 25.5 +/- 22.3 minutes to 11.3 +/- 8.2 minutes (P < 0.001). These results were similar when accessory pathway and selective AV nodal pathways ablations were separately evaluated. Following the initial staff training, during which the expected 80%-90% success rate is achieved, additional training will reduce the recurrence rate and the duration of the procedures at a similar level of success.

Single lead VDD pacing: multicenter study.

Optimal treatment for patients with AV block and normal sinoatrial node (SA) function entails atrial sensing and ventricular pacing (VDD mode). Single-lead VDD pacing preserves AV synchrony, precludes the need to insert two leads, and makes the implanter's work simpler and quicker. Our objectives were to verify the performance of the Thera VDD pacing system (medtronic, Inc., Minneapolis, MN, USA), and evaluate the effectiveness of its atrial sensing and its ventricular sensing and pacing. In 165 patients, 150 adults (mean age 62 +/- 18 years) and 15 children (mean age 7 +/- 5 years) with 1 degree-3 degrees AV block and normal SA node function, a Thera VDD system (Models 8948 or 8968) was implanted. Intraoperative ventricular electrical measurements were not significantly different from those of VVI pacemakers. The mean amplitude of the atrial signal during implantation was 4.1 +/- 1.9 mV. Optimal atrial signals during implantation were usually obtained in the mid or lower part of the right atrium by using a special technique. Adequate atrial measurements remained stable throughout 24 months. There was no difference between serial measurements of atrial signal amplitudes at predischarge and during follow-up visits. Reposition of the lead was done in 2 patients (1.4%), and reprogramming to VVI in 7 patients: due to atrial fibrillation in 3 (1.8%) and due to atrial undersensing in 4 patients (2.4%). Thera VDD pacing is reliable and easy to manage with dependable atrial sensing and ventricular pacing. The survival rate of VDD pacing at 2 years was 96%.

Columbia University's fellowship in public psychiatry.

In 1981 the fellowship in public psychiatry was established at New York State Psychiatric Institute and Columbia University College of Physicians and Surgeons to provide subspecialty training for psychiatrists who plan careers in the public sector. Ten one-year postresidency fellowships are awarded annually. The fellowship consists of supervised work and didactic experiences focused on the clinical modalities most effective in public mental health services and the managerial skills that the psychiatrist must possess to make those services work well. Fellows work three days a week at collaborating public-sector agencies throughout the New York metropolitan area. The curriculum includes an academic seminar, which gives fellows an introductory overview of major topics in public psychiatry; an organizational practicum, which is an exercise in management principles and practices; an evaluation practicum, which addresses the theory and practice of program evaluation; and an applied seminar, organized as a cycle of clinical, administrative, fiscal, and evaluation presentations in which each fellow applies the concepts learned in the other seminars to his or her field placement work. Of the 75 fellows who have graduated from the program, only six have chosen to leave the public arena. Nearly all work full time in the public sector, where more than half hold management positions. More than three-fourths hold academic appointments at medical schools in the area in which they are working as public psychiatrists.

Combined isoproterenol and epinephrine for the resuscitation of patients with cardiac asystole secondary to coronary artery disease.

In summary, the use of isoproterenol as an adjuvant to epinephrine in asystolic patients may increase the likelihood of return of spontaneous circulation.

Acute myocardial infarction--the angiographic picture: new insights into the pathogenesis of myocardial infarction.

The angiographic appearance of the coronary arteries were examined in 302 patients with stable angina pectoris and compared to 308 patients with acute myocardial infarction, who received high-dose intravenous thrombolytic therapy, in order to elucidate the underlying angiopathological picture in the two diseases. In each group coronary lesions were present in proximal segments of the arteries and were closely related to bifurcations. Lesions were more extensively distributed in the coronary tree in patients with stable angina and they had an average of 5.4 lesions per patient, compared to the acute myocardial infarction group who had only 2.4 lesions. Also, in the acute myocardial infarction patients, four-fifths of the culprit arteries were patent, 104 (34%) had a ruptured plaque, 22 (7%) had an ulcerated plaque and in 190 (62%) the lesions were eccentric. The study shows that patients with myocardial infarction who are suitable for thrombolysis have a unique coronary angiographic picture and the acute episode is caused by sudden rupture of a localized atheromatous plaque which initiates an obstructive thrombotic cascade.

The effect of overdrive pacing rate and duration on ventricular escape rhythms in patients with chronic complete atrioventricular block.

The effect of overdrive (OD) pacing rate and duration on subsidiary pacemakers was evaluated in 54 patients with third-degree AV block. They had a permanent pacemaker implanted 61 +/- 56 months earlier because of complete AV block in 38 patients and, in 16 patients because of second-degree AV block, which in the interim advanced to complete AV block. The patients had a reliable infranodal escape rhythm, with a mean cycle length of 2,022 +/- 603 msec, upon discontinuation of the ventricular OD pacing, at a rate of 40 beats/min. The escape interval and escape rhythm cycle length was evaluated after OD pacing at 40, 50, 60, 70, 90, and 100 beats/min for 30 seconds, at each rate. In 100% of the patients the subsidiary pacemaker recovered after OD pacing at 40 and 50 beats/min and the number decreased to 59% at a rate of 100 beats/min. The escape interval prolonged gradually between OD pacing at 40 and 100 beats/min, by 56%. The effect of OD pacing duration at 50 and 70 beats/min was evaluated. At an OD pacing rate of 70 beats/min there was a significant effect of the pacing duration on the escape interval. There were significant differences in the escape interval duration and escape rhythm cycle length between males and females, patients with or without coronary artery disease, and patients with narrow or wide QRS escape. However, the increase in the OD pacing rate had a similar effect on the escape interval in the above mentioned groups. There was no effect on the paced QRS duration and sinus cycle length at each OD pacing rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Single physician approach to radiofrequency catheter ablation in patients with supraventricular tachycardia.

The minimal requirements for safe and effective performance of catheter ablation using radiofrequency current are still unclear. To determine the feasibility and safety of single physician approach to catheter ablation of supraventricular tachycardia substrate using radiofrequency energy, the results of the ablation procedure in 52 consecutive patients were evaluated. The procedures were performed during 1 year by the same physician and nurse. Twenty-one patients had selective atrioventricular (AV) nodal pathway ablation and 31 patients had accessory AV pathway ablation. Forty-eight patients (89%) had the diagnostic and the ablative procedure during the same electrophysiological test. In the 21 patients with AV nodal reentrant tachycardia, all had successful selective ablation of the fast (13) or the slow (8) pathways. Eight patients had recurrence of the clinical tachycardia and had a successful reablation. No patient developed complete AV block or other significant complications. The mean fluoroscopy time during the procedure was 16.0 +/- 8.6 minutes. In the eight patients with Wolff-Parkinson-White syndrome, all concealed accessory pathways were successfully ablated with a mean fluoroscopy time of 30.0 +/- 27.9 minutes. Two patients had recurrence of the conduction through the accessory pathway and had a successful reablation. Eighteen of 19 patients with a single overt accessory pathway had successful ablation, with a fluoroscopy time of 22.7 +/- 20.6 minutes. Three patients had an early recurrence of the conduction through the accessory pathway, reablation was successful in two of them. Ten accessory pathways were ablated in four patients with multiple pathways during nine procedures. Only two patients developed minor peripheral vascular complications.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison between patients with and without reliable ventricular escape rhythm in the presence of long standing complete atrioventricular block.

The underlying heart rhythm was evaluated in 74 patients with complete atrioventricular block and had a permanent pacemaker implantation. The pacing was inhibited for 10 seconds or until the patient developed symptoms of presyncope or syncope. Fifty-six patients (74%) had a reliable escape with a mean cycle length of 2010 +/- 596 msec and a mean escape interval of 2335 +/- 971 msec. In 93% of these patients the escape interval was < 4 seconds. The patients without reliable escape (24%), developed symptoms only after a mean of 7153 +/- 1875 msec. The duration of the conduction disorder was longer in the patients without escape and the intraventricular conduction was slower. More patients without escape were treated and antiarrhythmic agents. Forty-eight patients were followed for 1 year and underwent at least two different studies and 13% had different results at different tests. In conclusion, patients without reliable escape have a longer history of conduction disorder, a slower intraventricular conduction, and are frequently treated with antiarrhythmic agents. Even patients with reliable escape occasionally may show a greater pacemaker dependence; therefore, they should also be considered as pacemaker dependent.