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Biomedical subjects

S Serge Barold

Publications and source records attributed to S Serge Barold.

At least 19 recordsLinked to original sources
PubMed2004

Twelve-lead electrocardiogram: the advantages of an orderly frontal lead display including lead -aVR.

BACKGROUND: It is possible that efforts in ECG review by both young experienced clinicians are currently discouraged-and risk to be completely dismissed-by the conventional (ie, disorderly) display of the frontal plane leads, with lead aVR at -150 degrees. METHODS: We reviewed studies on the usefulness of leads aVR and -aVR as well as on the history of the frontal leads in electrocardiography. RESULTS: Lead aVR and particularly, lead -aVR, provide useful information when systematically analyzed. In addition, if lead -aVR is examined in its anatomically logical sequence, ie, aVL, I, -aVR, II, aVF, and III, the frontal plane of the 12-lead ECG is more easily understood. This "panoramic" or "orderly" display is in common use in countries such as Sweden, but it is rarely seen in the United States. CONCLUSIONS: ECG interpretation would be enhanced by displaying the limb leads in an orderly arrangement that starts with lead aVL and ends with lead III, and many ECG changes would be ideally displayed by a lead -aVR at 30 degrees.

Arrhythmias, Cardiac↗
PubMed2004

Sleep apnea: a new indication for cardiac pacing?

In the general adult population, prevalence of sleep apnea syndrome reaches 4% in men and 2% in women. Continuous positive airway pressure is the most efficient treatment. At the present time, although severe atrial bradycardias could occur during sleep apnea episodes, cardiac pacing has not been demonstrated as an efficient treatment for those bradycardias. Treating sleep apnea generally reduces the number of bradyarrhythmias. However, recent studies reported a beneficial effect of atrial pacing on the sleep apnea burden. The mechanisms rely on two phenomena: first to counteract nocturnal hypervagotonia, and second to treat heart failure. By increasing the heart rate, cardiac output improves, which mitigates pulmonary subedema. Consequently, stimulation of the pulmonary afferent vagal fibers is diminished, which reduces central sleep apnea incidence. During nocturnal hypervagotonia, snoring and obstructive apnea episodes are increased, mainly due to an excessive muscular relaxation of the upper airway area inducing cyclical substantial decreases in the airway caliper. In patients with a low heart rate, atrial pacing can counteract hypervagotonia by enhancing the sympathetic tone and modifying the degree of vigilance. Accordingly, in the near future, sleep apnea treatment might potentially rely on atrial pacing in bradycardic patients with hypervagotonia (with or without heart failure). The role of the physician would then be not only to diagnose sleep apnea, but also to identify potential responders to cardiac pacing.

Adult↗
PubMed2004

Pacemaker and implantable cardioverter defibrillator implantation without reversal of warfarin therapy.

The study evaluated all patients undergoing permanent pacemaker and ICD implantation over a 4-year period to determine if anticoagulated patients required normalization of coagulation factors in the periprocedural period. The study included 1,025 (597 men, 428 women, age 24-100 years, mean 72 years) consecutive patients who underwent device implantation using mostly a percutaneous subclavian approach. The procedures were performed without reversal of anticoagulation in 470 patients with INRs >or= 1.5 at the time of the procedure (mean INR 2.6 +/- 1.0, range 1.5-7.5). The complication rate in the anticoagulated group was similar to those in patients with a normal INR. Routine normalization of coagulation factors prior to pacemaker/ICD placement may not be necessary.

Adult↗
PubMed2004

Aortic perforation by active-fixation atrial pacing lead.

This report describes perforation of the aorta related to the implantation of an active-fixation atrial pacing lead, a previously undocumented complication of pacemaker implantation. The complication was related to excessive tissue penetration by the screw at the tip of the lead or perforation of the lead body by the positioning stylet during manipulation whereupon the stylet traversed the atrial wall and aortic wall. Perforation of the aorta should be part of the differential diagnosis of cardiac tamponade after pacemaker implantation.

Adult↗
PubMed2004

Right ventricular outflow tract placement of defibrillation leads: five year experience.

Over a 5-year period, 112 patients (89 male/23 female, mean age 65 years) underwent right ventricular outflow tract (RVOT) placement of permanent active-fixation transvenous pacing/defibrillating leads. At implantation, the pacing threshold was 0.6 +/- 0.3 V at 0.5 ms pulse duration and R wave amplitude was 10.9 +/- 4.9 mV. The defibrillation threshold (DFT) of right-sided implants was 17.7 +/- 3.4 J while that of left-sided implants was 16.1 +/- 3.3 J. Patients were followed at 1 and 3 month postimplant and at six-month intervals thereafter. At mean follow-up of 22.5 +/- 17.5 months (range 1-47 months) there were no lead dislodgments, unsuccessful shock therapies, or failure to sense or pace for bradycardia or tachycardia. Death was not sudden in the 17 patients who died. We conclude that RVOT pacing-defibrillation lead implantation is safe, efficacious, and potentially attractive because preliminary evidence suggests that it may not be associated with the adverse hemodynamic effects of pacing at the right ventricular apex.

Adult↗
PubMed2004

Treatment of sustained left atrial tachycardia by ostial pulmonary vein isolation.

This report describes two patients with sustained regular left atrial tachycardias originating from multiple pulmonary veins in the absence of clinical evidence of atrial fibrillation. The tachycardias were eliminated by activation map-guided pulmonary vein isolation. Stable sustained regular pulmonary vein tachycardias unassociated with atrial fibrillation are uncommon, and they belong to the spectrum of pulmonary vein arrhythmias that include the more common paroxysmal and unstable tachycardias engendering atrial fibrillation.

Adult↗
PubMed2003

Willem Einthoven and the birth of clinical electrocardiography a hundred years ago.

The first electrocardiogram (ECG) from the intact human heart was recorded with a mercury capillary electrometer by Augustus Waller in May 1887 at St. Mary's Hospital, London. The tracings were poor and exhibited only 2 distorted deflections. Willem Einthoven (1860-1927) who was professor of physiology at the University of Leiden, The Netherlands, began his studies of the ECG with the mercury capillary electrometer, and improved its distortion mathematically so that he was finally able to register a good representation of the ECG before the beginning of the twentieth century. He later further improved ECG recordings with the introduction of a string galvanometer of his design. Einthoven published his first article about the string galvanometer in 1901, followed by a more detailed description in 1903 which included a report of ECGs taken with the new instrument. The year 2002 marks the centennial of Willem Einthoven's first recording of the ECG in a clinically applicable fashion with the string galvanometer. The clinical use of Einthoven's immobile equipment required transtelephonic transmission of the ECG from the physiology laboratory to the clinic at the Academic Hospital about a mile away as documented in the 1906 paper on the "télécardiogramme". This report contained a wealth of ECG patterns and arrhythmias. Einthoven developed a system of electrocardiographic standardization that continues to be used all over the world and introduced the triaxial bipolar system with 3 limb leads and thus established uniformity of the recording process. Einthoven also conceived the famous equilateral triangle with leads I, II, and III at its sides and the calculation of the electrical axis (in the frontal plane) depicted as a single vector with an arrow at the center of the triangle. Einthoven recognized the great potential importance of the ECG as a diagnostic and investigative tool and his achievements made him the founder of modern electrocardiography. He was awarded the Nobel Prize in 1924 (2 years after Waller's death) in physiology and medicine, "for the discovery of the mechanism of the electrocardiogram."

Electrocardiography↗
PubMed2003

Shortening of the sensed AV delay of a dual chamber pacemaker during normal sinus rhythm.

We studied the Medtronic Thera and Kappa 400 dual chamber pacemakers to determine the causes and mechanism of shortening of the sensed AV delay during normal sinus rhythm. When the sensed AV delay shortens to less than its programmed value, it lengthens gradually and returns to its programmed duration after a number of pacing cycles. This behavior is linked to the relatively slow automatic mode switching algorithm (AMS) and was observed when a transient increase in the sensed atrial rate failed to reach the point where AMS was activated and also upon exit from the AMS mode.

Cardiac Pacing, Artificial↗
PubMed2003

Ventricular rate stabilization algorithm of ICD causing dual chamber pacing during ventricular tachycardia.

Some implantable cardioverter-defibrillators (ICD) are designed with a ventricular rate stabilization (VRS) algorithm triggered by sensing a pacemaker-defined ventricular premature complex, for the prevention of "short-long-short" sequences that may predispose to ventricular tachycardia (VT). The VRS algorithm initiates AV sequential pacing at a relatively fast and decreasing rate according to a programmable sequence. This report describes a complex manifestation of ICD function where activation of the VRS algorithm produced AV sequential pacing during sustained VT. This response occurs when there is an appropriate relationship between the timing cycles of the ICD and a relatively slow VT.

Aged↗
PubMed2003

A case of pacemaker and pacemaker-like syndrome.

This report describes the occurrence of both pacemaker syndrome and a pacemaker-like syndrome (so-called "pseudopacemaker syndrome") in a patient who exhibited an atrioventricular junctional rhythm probably on the basis of sick sinus syndrome. The clinical and hemodynamic manifestations of the two clinical situations were similar and associated with regular retrograde ventriculoatrial conduction. The abnormalities during the junctional rhythm were reproduced during ventricular pacing. Surprisingly, the occurrence of the pacemaker-like syndrome during junctional rhythm in patients with normal left ventricular function has rarely been described.

Aged↗
PubMed2003

Far-field R wave sensing causing prolongation of the atrial escape interval of DDD pacemakers with atrial-based lower rate timing.

This report describes the occurrence of prolonged atrial escape intervals (AEI) initiated by sensing of ventricular premature complexes (VPC) without a preceding atrial depolarization or an AV delay in two patients with DDD pacemakers with an atrial-based lower rate response. The prolonged AEIs were due to ventriculoatrial cross-talk so that atrial sensing of the far-field R wave of the VPCs occurred before detection of the R wave by the ventricular channel as a near-field signal. Early atrial sensing of the far-field R wave was promoted by a high atrial sensitivity and/or low ventricular sensitivity and was eliminated by reducing atrial sensitivity and/or increasing ventricular sensitivity. This manifestation of far-field sensing should not be interpreted as malfunction of dual chamber pacemakers with atrial-based lower rate timing.

Cardiac Pacing, Artificial↗