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Wai-Hong Chen,
Upendra Kaul, Sum-Kin Leung,
Yuk-Kong Lau,
Huay-Cheem Tan,
Albert Wai-Suen Leung,
Michael Kang-Yin Lee,
Shu-Kin Li,
William Ng,
Pui-Yin Lee,
Kwok-Fai Lam,
Hung-Fat Tse,
Chu-Pak Lau
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ABSTRACT: Coronary stenting is associated with a high incidence of restenosis in patients with diabetes mellitus. Recent data suggest that diabetic patients treated with abciximab have a lower rate of target vessel revascularization (TVR). We sought to investigate whether abciximab can reduce in-stent restenosis after coronary stenting in diabetic patients.
In this prospective double-blind trial, we randomly assigned 254 patients with type 2 diabetes mellitus undergoing nonurgent coronary stenting to receive abciximab with an initial heparin bolus of 50 U/kg (n = 128) or placebo with an initial heparin bolus of 70 U/kg (n = 126). All patients received aspirin and clopidogrel before the procedure. The primary endpoint was angiographic restenosis by quantitative coronary angiography at 6 months. The secondary endpoint was death, myocardial infarction (MI), or target lesion revascularization (TLR) at 6 months.
The clinical, angiographic, and procedural characteristics were matched between the 2 groups. Angiographic follow-up was completed in 226 patients (90%). Angiographic restenosis occurred in 29.1% of the abciximab group, and 24% of the placebo group (p = 0.30). The rates of the secondary endpoint were similar between the 2 groups (23.4% in the abciximab group versus 22.2% in the placebo group; p = 0.88). TLR was performed on 36 (18.4%) lesions in 29 (23.4%) patients of the abciximab group, and 26 (13.6%) lesions in 23 (18.3%) patients of the placebo groups, respectively (p = 0.21 and 0.35, respectively).
Abciximab does not reduce angiographic restenosis or TLR in type 2 diabetic patients undergoing nonurgent coronary stenting.
The Journal of invasive cardiology 11/2005; 17(10):534-8. · 1.84 Impact Factor
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ABSTRACT: While the hemodynamic and clinical significance of automatic mode switching (AMS) in patients with pacemakers has been demonstrated, the clinical behavior of AMS algorithms differ widely according to the manufacturers and pacemaker models. In general, a "rate-cutoff" detection method of atrial tachyarrhythmias provides a rapid AMS onset and resynchronization to sinus rhythm at the termination of atrial tachyarrhythmias, but may cause intermittent oscillations between the atrial tracking and AMS mode. This can be minimized with a "counter" of total number of high rate events before the AMS occurs. The use of a "running average" algorithm results in more stable rate control during AMS by reducing the incidence of oscillations, but at the expense of delayed AMS onset and resynchronization to sinus rhythm. Algorithms may be combined to fine tune the AMS response and to avoid rapid fluctuation in pacing rate. Appropriate programming of atrial sensitivity, and the avoidance of ventriculoatrial cross-talk are essential for optimal AMS performance.
Pacing and Clinical Electrophysiology 08/2002; 25(7):1094-113. · 1.35 Impact Factor
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ABSTRACT: Automatic mode switching (AMS) is now a programmable function in most contemporary dual chamber pacemakers. Atrial tachyarrhythmias are detected when the sensed atrial rate exceeds a "rate-cutoff," "running average," "sensor-based physiological" rate, or using "complex" detection algorithms. AMS algorithms differ in their atrial tachyarrhythmia detection method, sensitivity, and specificity and, thus, respond differently to atrial tachyarrhythmia in terms of speed to the AMS onset, rate stability of the response, and speed to resynchronize to sinus rhythm. AMS is hemodynamically beneficial, and most patients with atrial tachyarrhythmias are symptomatically better with an AMS algorithm in their pacemakers. New diagnostic capabilities of pacemaker especially stored electrograms not only allow programming of the AMS function, but enable quantification of atrial fibrillation burden that facilitate clinical management of patients with implantable devices who have concomitant atrial tachyarrhythmia.
Pacing and Clinical Electrophysiology 07/2002; 25(6):967-83. · 1.35 Impact Factor
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ABSTRACT: Angiotensin-converting enzyme (ACE) inhibitors reduce mortality in patients with acute myocardial infarction (AMI), but these benefits might be limited by acute hemodynamic changes and difficulties in titrating to recommended doses. The objective of this study was to compare the hemodynamic changes and tolerability of perindopril with captopril after AMI. We randomized 212 patients to receive either captopril (n = 102) or perindopril (n = 110) within 72 hours of AMI. Captopril was given as an initial dose of 6.25 mg, and then 50 mg/day on day 1 and 100 mg/day thereafter. The corresponding doses of perindopril were 2, 4, and 8 mg/day. Acute hemodynamic changes, the percentage of patients who reached target doses, and in-hospital and 6-month cardiovascular events were monitored. Baseline clinical characteristics of the 2 groups were identical, but patients randomized to perindopril were in a higher Killip class (1.4 +/- 0.6 vs 1.2 +/- 0.5, p = 0.05). During the first 6 hours, treatment with perindopril resulted in higher minimal systolic (97 +/- 15 vs 91 +/- 14 mm Hg, p <0.01) and diastolic blood pressure (BP) (57 +/- 11 vs 54 +/- 10 mm Hg, p <0.02), later occurrence of minimal BP (3.6 +/- 0.2 vs 2.7 +/- 0.1 hour, p <0.001), and a lower incidence of persistent hypotension with systolic BP < 90 mm Hg for > or =1 hour (5% vs 16%; p < 0.01) compared with captopril. At initial administration, target doses of perindopril and captopril were attained in 97% and 82% of the patients, respectively (p < 0.01). After 6 months, there were no differences between patients treated with perindopril and captopril in mortality rates (6% vs 13%, p = 0.16) and need for revascularization (20% vs 21%, p = 0.9). Thus, in patients during AMI, perindopril treatment showed better short-term tolerance than treatment with captopril, with significantly less acute hemodynamic changes and fewer withdrawals.
The American Journal of Cardiology 01/2002; 89(2):150-4. · 3.37 Impact Factor
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ABSTRACT: TSE, H.–F., et al.: A Cephalic Vein Cutdown and Venography Technique to Facilitate Pacemaker and Defibrillator Lead Implantation. The aim of this study was to assess the feasibility of a cephalic vein cutdown and venography technique for implantation of a pacemaker or ICD and to determine the causes of failure of cephalic vein cutdown. In consecutive patients who underwent pacemaker or ICD implants, a modified cephalic vein guidewire technique was performed. This technique was attempted in 289 pacemaker implants and 26 ICD implants (155 men, 160 women; mean age 74 ± 10 years). The success rate for implantation of a single chamber and a dual chamber device by using this technique alone was 84% (54/64) and 74% (185/251), respectively (P = 0.10). In an additional 7% of patients with dual chamber implant, the cephalic vein can be used for passage of the ventricular lead. A cephalic venogram was required in 82 patients and facilitated the passage of the guidewire in 62 (79%) of them. No complication related to vascular access was observed with this technique. This technique failed in 54 (17%) of 315 patients due to (1) failure of cephalic vein isolation (48%), (2) venous stenosis (24%), or (3) venous torturosity or anomalies (28%). There were no significant differences in the patient's age, sex, type of device, and the fluoroscopic time for lead placement between patients with or without successful lead placement using this technique (all P > 0.05). In conclusion, a simple modification of the cephalic vein guidewire technique together with venography has facilitated the placement of leads during pacemaker and ICD implant. This technique is safe and applicable in the majority of patients and avoids the risk of subclavian puncture.
Pacing and Clinical Electrophysiology 03/2001; 24(4):469 - 473. · 1.35 Impact Factor
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ABSTRACT: Automatic mode switching (AMS) is a useful means to avoid rapid ventricular response during atrial fibrillation (AF), but AMS cannot occur if the detected atrial rate during AF is below the mode switching criteria. This may be the result of antiarrhythmic medications, or when the atrial events fall within the atrial blanking period, or if the atrial amplitudes during AF are too small to be sensed. We hypothesize that the addition of an automatic rate switching (ARS) algorithm may complement AMS response during AF with different detected atrial rates. We studied the Marathon DDDR pacemaker (Model 294–09, Intermedics Inc.) with the AMS and ARS algorithms that are independently programmable but can also operate in combination. AF sensed above the AMS rate (160 beats/mm) will lead to VDIR pacing, whereas AF below AMS rate will be tracked at an interim rate as dictate by the ARS, at a ventricular response that is 20 beats/min above the sensor indicated rate. Atrial tachyarrhythmias were simulated by chest wall stimulation (CWS). CWS was applied to 33 patients (16 men, 17 women, mean age 69 ± 11 years) with a Marathon DDDR pacemaker using an external pacer to simulate AF occurring at two rate levels: above the AMS rate (programmed at 160 beats/min) at 180 beats/min and below the AMS rate at 120 beats/min. The maximum, minimum, and mean ventricular rates during CWS in DDDR mode with AMS alone, ARS alone, and their combination were compared. During CWS at 120 beats/min, the AMS plus ARS setting showed a mean ventricular rate of 79 ± 3 beats/min and 124 ± 14 beats/mm in the AMS setting alone (P < 0.01). With CWS at 180 beats/min, the mean ventricular rate in the AMS plus ARS setting compared to the AMS setting alone was not significantly different. However, the variation in ventricular pacing rate was 7 ± 14 beats/min in the AMS plus ARS setting and 40 ± 42 beats/min in the AMS setting (P < 0.05). In conclusion, AMS is effective for simulated atrial tachyarrhythmias sensed above the AMS rate. Combined AMS with ARS is useful to handle simulated atrial tachyarrhythmia at a slower rate and to avoid rate fluctuation during AMS. There is also a possibility that this can be applied to the naturally occurring atrial tachyarrhythmias.
Pacing and Clinical Electrophysiology 04/2000; 23(5):824 - 831. · 1.35 Impact Factor
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ABSTRACT: Automatic mode switching (AMS) prevents tracking of paroxysmal atria] fibrillation (AF) in dual chamber pacing. The correct detection of AF can be affected by the programmed atrial sensitivity (AS). We prospectively studied the relationship between AS, AF under-sensing, an d AMS, using unfiltered bipolar in tracardiac atrial electrogram s recorded from 17 patients during sinus rhythm (SR) and in AF. Overall, 780 rhythms were recorded and replayed onto three dual chamber pacemaker models using different AMS algorithms (Thera DR 7940, Marathon DDDB 294–09, and Meta DDDH 1254), and the ventricular responses were measured. AS was randomly programmed in steps from the highest available AS to half of the mean atrial P wave amplitude (PWA), and the percentage of appropriate AMS responses (defined as a ventricular pacing rate at the expected AMS mode) were recorded. AMS efficacy was related to the programmed AS settings in an exponential manner. At low AS settings, a higher percentage of tests were associated with absence of, or with intermittent AMS and tracking of AF, whereas at higher AS, oversensing of noise during SR occurred. An optimal AS measured approximately 1.3 mV, representing about one-third of the PWA measured during SR, although oversensing of SR and undersensing of AF continued to occur in 14% of tests and time, respectively, due to the high variation in PWA during AF. Thus, a fixed AS cannot eliminate AF undersensing without inviting noise oversensing, suggesting the need for automatic adjustments of AS, or the use of a rate-limiting algorithm to prevent rate oscillation during intermittent AF sensing. In conclusion, AMS functions of existing pacemakers were significantly limited by the undersensing of AF and oversensing of noise. Proper adjustment of the AS is important to enable effective AMS during AF.
Pacing and Clinical Electrophysiology 10/1998; 21(11):2214 - 2219. · 1.35 Impact Factor
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ABSTRACT: Background and hypothesis: Occasional reports have suggested that cellular phones may interfere with permanent pacemakers. Our investigation sought to determine systematically the effects of commercially available cellular phones on the performances of different pacing modes and sensing lead configurations of permanent implanted pacemakers.Methods: We conducted the study in 29 patients implanted with single- or dual-chamber bipolar rate-adaptive permanent pacemakers (a total of nine different models and six different sensors: minute ventilation, activity sensing using either accelerometer or piezoelectric crystal, QT and oxygen saturation sensing) from four different manufacturers. Three different cellular phones with analog or digital coding with maximum power from 0.6 to 2 W were used to assess the effect of pacemaker interference. Each cellular phone was positioned at (1) above the pacemaker pocket, (2) the ear level ipsilateral to the pacemaker pocket, and (3) the contralateral ear level. Surface electrocardiograms, intracardiac electrograms, and marker channels were recorded where possible during the following maneuvers at each position: (1) calls made by a stationary phone to a cellular phone, and (2) calls made from the cellular phone to a stationary phone. A total of eight different pacing modes [DDD(R), VDD(R), AAI(R) and VVI(R)] in both unipolar and bipolar sensing configurations was tested.Results: Interference was demonstrated during cellular phone operation in 74 of 2,418 (3.1%) episodes in eight patients. Three types of interference were observed: inhibition of pacing output, rapid ventricular tracking in DDD(R) or VDD(R) mode, and asynchronous pacing. All were observed only with the cellular phone positioned above the pacemaker pocket. Interference occurred prior to and after the termination of the ringing tone of the cellular phone in 57% of cases. Cellular phones with either digital or analog technology could cause interference. Unipolar atrial lead was most susceptible to interference (relative frequency of interference: unipolar 1.8%, bipolar 0.4%, p<0.05;atrial 2.9%, ventricular 1 %, p <0.05). There was no sensor-driven rate acceleration during all tests. In all patients, reprogramming of the sensitivity level successfully prevented cellular phone interference.Conclusions: Commercially available cellular phones can cause reversible interference to implanted single- or dual-chamber permanent pacemakers. The effect is maximal with high atrial unipolar sensitivity, especially in single pass VDD(R) systems. Both digital and analog cellular phones can lead to interference. Pacemaker interference can occur prior to a warning sign (ringing tone) of the phone and may have significant implications in patient safety.
Clinical Cardiology 10/1996; 19(11):881 - 886. · 2.15 Impact Factor
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ABSTRACT: Floating P wave sensing can be derived from bipolar atrial electrodes with different electrode configurations, although the relative clinical efficacy of these methods of atrial sensing has not been studied. We evaluated 32 sex and age matched patients with advanced AV block who received A V synchronous pacers using either a single lead with diagonally arranged bipole (Unity VDDR, Model 292, Intermedics Inc.) or closely spaced bipolar complete ring electrodes (Them VDD, Model 8948, Medtronic Inc.). The total surface area of the atrial electrodes were 17.2 and 25 mm2, and the highest programmable atrial sensitivities were 0.1 and 0.25 mV, respectively. Atrial electrogram amplitude and sensing threshold were evaluated at implant and at each follow-up clinic visit (1, 3, and 6 months), Stability of atrial sensing was assessed during physical maneuvers, treadmill exercise test, and Holier recording. Atrial electrogram amplitude at implantation was higher in the Them VDD (2.08 ± 0.79 vs 1,45 ± 0.59 mV in Unity VDDR; P < 0.05), but the value of atrial sensing threshold was lower during follow-up than Unity VDDR. P wave undersensing was additionally observed with both pacemakers during physical maneuvers and exercise testing (6%-19% of patients). Two and four patients had atrial undersensing on Holter in the Unity VDDR and Them VDD, respectively, and the percentage P wave undersensing were 0.88%± 2.41% versus 3.63%± 8.16%, respectively. Reprogramming of the atrial sensitivity in the Unity VDDR and the use of investigational software allowing 0.18 mV atrial sensitivity to be programmed in the Them VDD substantially reduced the percentage of P wave undersensing on Holter to 0.46%± 1.67% and 0.10%± 0.24%, respectively. Beginning at discharge with a programmed atrial sensitivity level at least twice the sensing margin, the mean atrial sensitivity level was reprogrammed from 0.29 to 0.26 mV for Unity VDDR and 0.33 to 0.24 mV for Them VDD at 6 months. There was no incidence of atrial oversensing. Despite differences in atrial amplitudes at implantation between the diagonally arranged bipole and closely spaced full ring single lead systems, the clinical performances of atrial sensing were similar at an appropriately high atrial sensitivities. The absence of atrial oversensing suggests that single pass VDD pacemakers should probably be programmed at the highest available atrial sensitivity to ensure adequate P wave sensing as guided by physical maneuvers and Holter recording to minimize the need of subsequent reprogramming.
Pacing and Clinical Electrophysiology 10/1996; 19(11):1574 - 1581. · 1.35 Impact Factor
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ABSTRACT: Optimal function of a single lead P wave synchronous rate adaptive ventricular pacing system (VDDR) requires reliable P wave sensing over time and during daily activities. The stability of P wave sensing and the incidence of sensitivity reprogramming in a single pass lead with a diagonally arranged bipole was assessed in 30 patients with complete atrioventricular block over a follow-up period of 12 ± 1 months (range 6 months to 3 years). Atrial sensing was assessed during clinic visits, by physical maneuvers (postural changes, breathing, Valsalva maneuver, walking and isometric exercise), maximum treadmill exercise and Holter recordings. P wave amplitude at implantation was 1.21 ± 0.09 (0.5–3.6) mV, and the atrial sensing threshold remained stable over the entire period of follow-up. Using an atrial sensitivity based on twice the sensing threshold at 1 month, P wave undersensing was found in 2, 4, 3, and 7 patients during clinic visit, physical maneuvers, exercise, and Holter recordings, respectively. Atrial sensitivity reprogramming was performed in three patients based on the correction of undersensing during physical maneuvers. Although eight patients had atrial undersensing on Holter recordings, the number of undersensed P waves was small (total 101 beats or 0.013%± 0.001% of total ventricular beats) and no patient was symptomatic. One patient had intermittent atrial undersensing at the highest sensitivity, but the VDDR mode was still functional most of the time. No patient had myopotential interference at ihe programmed sensitivity. One patient developed chronic atrial fibrillation and was programmed to the VVIR mode. Thus, single lead VDDR pacing is a stable pacing mode in 97% of patients. Because of the large variability of P wave amplitude, the use of a sensitivity margin at least three times the atrial sensitivity threshold will maximize atrial sensing and minimize the need for atrial sensitivity reprogramming (1/30 patients). Physical maneuvers and exercise tests are effective means for rapid assess ment of the adequacy of P wave sensing.
Pacing and Clinical Electrophysiology 10/1994; 17(11):1849 - 1853. · 1.35 Impact Factor
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ABSTRACT: Rapid ventricular tracking response to supraventricular tachyarrhythmia is one major limitation to DDD pacing. In a DDDR pacemaker, sensor-based algorithms have been used to control these arrhythmias. These include the use of an interim rate limit (conditional ventricular tracking limit) or a separate maximum tracking and sensor rate limits (discrepant upper rate). These algorithms limit inappropriate ventricular pacing rate during tracking of pathological supraventricuiar tachyarrhythmia and atrial flutter by Wenckebach-like prolongation of the AV interval. We observed that this may cause an unexpected extension of the AV interval in patients with high atrial rate and intact AV nodal conduction. This was due to P wave rate above the conditional ventricular tracking limit or maximum tracking limit, but AV paced interval prolongation was avoided by the occurrence of intrinsic conduction, albeit at an AV interval longer than the programmed AV interval. This might appear as failure of ventricular pacing on the ECG. This phenomenon is a modified form of “upper rate” behavior occurring in the AV interval, and should be recognized as a normal behavior rather than pacemaker malfunction.
Pacing and Clinical Electrophysiology 02/1994; 17(3):321 - 330. · 1.35 Impact Factor
