Accepted for publication 26 February 1991 After the first permanent pacemaker implantation in 1958,' the initial developments in pacemaker technology were aimed towards more efficient pacemaker performance. The standard mode of pacing in these early years was single chamber ventricular stimulation and t-his became established as effective lifesaving therapy.2 Over the past 10 years, however, there has been a wealth of different Table 1 NBG pacemaker code

/pdf/recommendations-for-pacemaker-prescription-for-symptomatic-1vvjzzrzwq.pdf

Recommendations for pacemaker prescription for symptomatic bradycardia

In contrast to asynchronous ventricular pacing (VOO, VVI), atrial synchronized ventricular pacing (VAT, VDD, DDD) maintains the normal sequence of cardiac chamber activation and permits a chronotropic response to exercise, thereby improving exercise performance. To assess the separate contributions of these two factors to improved work capacity, 14 patients with implanted programmable VAT pacemakers were exercised according to the Bruce protocol, in three different pacing modes, selected in a random order and on a double blind basis: (a) VAT; (b) chest wall stimulation triggered ventricular (V-CWS-T) pacing, during which the pacemaker was programmed to VAT mode but driven externally using chest wall stimulation at rates fractionally above the patients' atrial rate, thereby providing a chronotropic response to exercise without atrioventricular synchronization; and (c) VOO mode at 70 beats per minute. There was a significant improvement in exercise performance in all patients during both VAT and V-CWS-T pacing as compared to VOO mode; the average increase in work capacity being similar: VAT: 44 +/- 31, (range, 12 to 140) percent and V-CWS-T; 40 +/- 24 (range, 5 to 85) percent. It is concluded that in patients with adaptive pacing systems, the chronotropic response is the major determinant of any improvement in exercise performance.

Atrial synchronized ventricular pacing: contribution of the chronotropic response to improved exercise performance.

Microsystem technologies (MST) have become the basis of a large industry. The advantages of MST compared to other technologies provide opportunities for application in implantable biomedical devices. This paper presents a general and broad literature review of MST for implantable applications focused on the technical domain. A classification scheme is introduced to order the examples, basic technological building blocks relevant for implantable applications are described and finally a case study on the role of microsystems for one clinical condition is presented. We observe that the microfabricated parts span a wide range for implantable applications in various clinical areas. There are 94 active and 67 commercial 'end items' out of a total of 142. End item refers to the total concept, of which the microsystem may only be a part. From the 105 active end items 18 (13% of total number of end items) are classified as products. From these 18 products, there are only two for chronic use. The number of active end items in clinical, animal and proto phase for chronic use is 17, 13 and 20, respectively. The average year of first publication of chronic end items that are still in the animal or clinical phase is 1994 (n = 7) and 1993 (n = 11), respectively. The major technology–market combinations are sensors for cardiovascular, drug delivery for drug delivery and electrodes for neurology and ophthalmology. Together these form 51% of all end items. Pressure sensors form the majority of sensors and there is just one product (considered to be an implantable microsystem) in the neurological area. Micro-machined ceramic packages, glass sealed packages and polymer encapsulations are used. Glass to metal seals are used for feedthroughs. Interconnection techniques such as flip chip, wirebonding or conductive epoxy as used in the semiconductor packaging and assembly industry are also used for manufacturing of implantable devices. Coatings are polymers or metal. As an alternative to implantable primary batteries, rechargeable batteries were introduced or concepts in which energy is provided from the outside based on inductive coupling. Long-term developments aiming at autonomous power are, for example, based on electrostatic conversion of mechanical vibrations. Communication with the implantable device is usually done using an inductive link. A large range of materials commonly used in microfabrication are also used for implantable microsystems.

https://iopscience.iop.org/article/10.1088/0960-1317/17/5/R02/pdf

Microsystem technologies for implantable applications

In this study, sequential cardiopulmonary exercise testing was used to assess the physiologic benefits of a single-chamber ventricular pacing system that utilizes a piezoceramic sensor to adjust heart rate by detecting "physical activity." An initial exercise test was conducted with the pacemaker programmed (based on a randomization table) to either the fixed rate (VVI, 70 beats/min) or rate-variable (VVI-Act) mode, and the results were compared with those obtained during a second exercise test in which the pacemaker was programmed to the alternate pacing mode. A 1.5 to 2 hr rest period was permitted between exercise tests, each of which consisted of a symptom-limited constant speed (3.0 mph) Balke protocol with 2 min stages commencing at 0.0% grade with increments of 2.5% at end of each stage. Compared with findings during fixed-rate VVI pacing, VVI-Act pacing was associated with greater exercise-induced positive chronotropic response (mean maximum heart rate VVI-Act 128 +/- 15.3 beats/min vs VVI 90 +/- 28.4 beats/min; p less than .01), prolongation of exercise duration (VVI-Act 10.2 +/- 3.8 min vs VVI 7.7 +/- 2.5 min; p less than .01), increased peak oxygen consumption (VVI-Act 1617 +/- 656 ml O2/min vs VVI 1325 +/- 451 ml O2/min; p less than .01), and onset of anaerobic threshold at a higher oxygen consumption (VVI-Act 1208 +/- 343 ml O2/min vs VVI 1064 +/- 377 ml O2/min: p less than .01). Additionally, of 44 comparable exercise stages tested in the two pacing modes, perceived exertion (assessed by a numerical grading system) was lower in 38 of 44 instances during VVI-Act compared with VVI pacing.(ABSTRACT TRUNCATED AT 250 WORDS)

Single-chamber cardiac pacing with activity-initiated chronotropic response: evaluation by cardiopulmonary exercise testing.

QT interval-heart rate relation during exercise in normal men and women: Definition by linear regression analysis

The relation between QT interval and heart rate has been studied in a group of patients undergoing physiological exercise, in a group undergoing atrial pacing without exercise, and in a group with complete heart block undergoing exercise at a fixed ventricular rate controlled by cardiac pacing. The expected shortening in QT interval during physiological exercise is only in part the result of the intrinsic effect of increased rate, since patients undergoing atrial pacing to comparable rates show only a small decrease in measured QT interval and patients exercising at fixed rates in heart block exhibit a decreasing QT interval related to the independent atrial rate. QT interval changes appear mainly to be governed by factors extrinsic to heart rate. The physiological control of QT interval has been used to construct a cardiac pacemaker which senses the interval between the delivered stimulus and the evoked T wave, and uses the stimulus-evoked T wave interval to set the subsequent pacemaker escape interval. Thus physiological control of cardiac pacing rate, independent of atrial activity, using conventional unipolar lead systems is possible.

https://heart.bmj.com/content/heartjnl/45/1/56.full.pdf

Relation between QT interval and heart rate. New design of physiologically adaptive cardiac pacemaker.

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Relation between QT interval and heart rate. New design of physiologically adaptive cardiac pacemaker.