Isolated Implantable Cardioverter Defibrillator Discharge

Approximately 60 to 80 of ICD patients will receive a shock therapy within 5 years of implant.20'21 Although ICD shocks are an expected occurrence, each event may frighten the patient, and these warrant careful evaluation by the physician. A flow diagram for the evaluation of ICD shocks is shown in Figure 10.8. Before they are discharged from the hospital after ICD implantation, patients should be educated about the procedures to follow after an ICD shock. Our practice is to have the patient...

Factors Limiting Successful Transvenous Left Ventricular Lead Placement

Cardiac Anatomy Pacing

Complex and unpredictable anatomic and technical considerations may preclude successful delivery of the LV lead to an optimal pacing site. Inability to Cannulate the Coronary Sinus It is difficult to estimate the true percentage of cases in which the coronary sinus cannot be cannulated because this is clearly influenced by operator experience. It is probably in the range of 1 to 5 .When the coronary sinus cannot be located by the superior approach, an adaptation of the inferior approach...

Pulse Generators And Lead Systems

Pacing Leads Line Drawing

Early ICD pulse generators were large and bulky. The size 115 to 145 cm3 and weight 195 to 235 g of these devices mandated abdominal implantation, typically in the left upper quadrant either subcutaneously or most often under the rectus muscle. The surgical procedure for abdominal ICD implantation is more extensive than for endocardial pacemakers, in part because it requires tunneling leads from the chest. The abdominal location of the pulse generator and the surgical procedure required were...

Tvt T1

Transcutaneous Pacing

Transcutaneous pacing electrode positions. Upper left Anterior cathodal patch placement over cardiac apex. Upper right Alternate anterior cathodal patch position over position of electrocardiographic chest lead V3. Lower left Posterior anodal patch centered between lower aspect of the left scapula and the spine. Lower right Placement of anterior anodal patch on the right chest. Note that cathodal negative electrode must be positioned anteriorly. stimuli, but capture must be...

Sensing And Pacing Thresholds

Intracardiac Electrograms

For manual sensing threshold determination, the device should first be re-programmed below the intrinsic rate to assess sensing. In single-chamber devices, ventricular sensing thresholds may be determined by then decreasing sensitivity i.e., increasing the millivolt values in the VVI mode to determine at what value Figure 11.10. Stored atrial top and ventricular bottom electrograms from a pacemaker with automated electrogram capture triggered by a high ventricular rate. The patient experienced...

Lead Design

Permanent pacing leads have five major components 1 the electrode s 2 the conductor s 3 insulation 4 the connector pin and 5 the fixation mechanism. Each of these components has critical design considerations, as well as failure modes. In this section, the factors that are important for design of leads are reviewed. As discussed previously in this chapter, the stimulation threshold is a function of the current density generated at the electrode.26,34-36 In general, the smaller the radius of the...

Mechanical Cardiac Pacing

Percussion Pacing

Mechanical cardiac pacing techniques stimulate myocardial tissue by direct or transmitted physical forces. Clinically, these techniques include percussion pacing chest thumps administered by a medical attendant and cough-induced cardiac resuscitation performed by patients themselves. Although they are lacking in technical sophistication, these techniques persist as useful clinical maneuvers by virtue of their sheer simplicity and immediacy of application. Percussion pacing for bradyarrhythmias...

Sinus Node Dysfunction

Bradycardia Patient

Sinus node dysfunction, or sick sinus syndrome and its variants, is a heterogeneous clinical syndrome of diverse etiologies.11 This disorder includes sinus bradycardia, sinus arrest, sinoatrial block, and various supraventricular tachycardias atrial or junctional alternating with periods of bradycardia or asystole. Sinus node dysfunction is quite common and its incidence increases with advancing age. In patients with sinus node dysfunction, the correlation of symptoms with the bradyarrhythmia...

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Dddr Pacemaker

VP VP VP VP VP VP VP VP VP VP VP VP VP VP Figure 6.32. Resting ECG tracing demonstrating AV sequential pacing at lower rate 55 ppm followed by paroxysmal atrial flutter with ventricular tracking at MTR 110 ppm . Diagram shows atrial paced events AP , atrial sensed events AS , and ventricular paced events VP , with the PVARP noted by the rectangle. Short, unlabeled ticks represent atrial activity that occurs in the PVARP and is not sensed. Diagram is based on Marker Channel, Medtronic, Inc.,...

Pharmacologic And Metabolic Effects On Stimulation Threshold

Stimulation Threshold Pacemaker

The stimulation threshold may demonstrate considerable variability over the normal 24-hour period, generally increasing during sleep and falling during the waking hours.54'55 The changes in threshold parallel fluctuations in autonomic tone and circulating catecholamines, and consequently there is a decreased threshold during exercise. The stimulation threshold is inversely related to the level of circulating corticosteroids. The stimulation threshold may increase following eating, during...

Interventricular Delay

Mitral Regurgitation Wigger

Optimal inter- and intraventricular coupling is more important than AV coupling for maximum ventricular pumping function. Normal ventricular electrical activation is rapid and homogeneous with minimal temporal dispersion throughout the wall. This elicits a synchronous mechanical activation and ventricular contraction. Exploration of the link between the sequence of cardiac electrical activation and mechanical function is one of the most exciting contemporary areas of research in heart failure...

Comparison of Atrial Based and Ventricular Based Systems

Atrial Based Timing

When the heart rate is considered, usually the ventricular rate is paramount, because it, not the atrial rate, causes the effective hemodynamic pulse. During periods of 2 1 AV block at the lower rate, a ventricular-based timing system Figure 6.27. Ventricular-based versus atrial-based timing. The lower portion demonstrates atrial escape timing after an atrial A pace in atrial-based timing. With this timing, the AVI after atrial pacing PAV always times out, regardless of ventricular inhibition....

1

Endless Loop Tachycardia

Crosstalk that occurs in the presence of a special crosstalk detection window triggers a ventricular output pulse rather than inhibiting it. This usually occurs at a shorter-than-programmed AV interval. Intermittent AV-interval shortening is seen in the two tracings. This reflects episodes of crosstalk triggering a ventricular output pulse. In the top tracing, for example, the second and ninth beats show AV-interval shortening. Figure 7.21. Crosstalk that occurs in the presence of...

Ventricular Undersensing Pvc Av Delay

Xray Pacemaker Header Set Screw Loose

Pacing stimuli present with intermittent failure to capture. The large unipolar stimuli are readily identified. The gentle downslope following the ineffective pacing stimulus is an RC decay curve. The pause is due to appropriate sensing of a native QRS, which is virtually isoelectric in this lead. RC resistance capacitance. Figure 7.1. Pacing stimuli present with intermittent failure to capture. The large unipolar stimuli are readily identified. The gentle downslope following the...

Dualchamber Pacing System Malfunction

Pacemaker Crosstalk

There are five major classes of dual-chamber pacing system malfunction. The first class includes all the abnormalities previously discussed as occurring with single-chamber pacing systems. The abnormalities in this case occur on one or both of the two channels of the dual-chamber system and, in recent years, this has been extended to either lead in a multisite atrial or ventricular system. Although this may sometimes be obvious, there are situations in which the problem will not be readily...

Revision of the Implanted Pacemaker System and Pulse Generator Change

Epicardial Biventricular Pacing

Revision of an implanted pacing system may involve replacement of the pulse generator, the pacing leads, or both Fig. 5.13 . The uncomplicated generator change is usually a simple procedure however, the preparation is in many ways Figure 5.13. PA chest radiograph of woman with congenital heart disease referred for biventricular pacing system upgrade. She has a dual chamber pacing system comprising two separate sets of unipolar transvenous leads arrowheads to both the atrium and ventricle. These...