Is Mode Switching Beneficial? A Randomized Study in Patients With Paroxysmal Atrial Tachyarrhythmias

AbstractObjectives. We sought 1) to compare three pacing modalities—DDDR with mode switching (DM), DDDR with conventional upper rate behavior (DR) and VVIR (VR)—in patients with a history of atrial tachyarrhythmias, and 2) to assess the efficacy of six mode-switching algorithms.Background. A history of atrial tachyarrhythmias has been a relative contraindication to dual-chamber pacing. Several mode-switching algorithms have recently been developed to prevent rapid tracking of atrial tachyarrhythmias.Methods. Forty-eight patients (mean age 64 years, 58% male) with a history of atrial tachyarrhythmias and heart block had a DM pacemaker implanted. Pacemakers were programmed to DM, DR and VR modes for 4 weeks each in a randomized crossover design. All subjects used a patient-activated electrocardiographic (ECG) recorder throughout the study and additionally underwent ambulatory ECG monitoring and a treadmill exercise test in each mode. They completed three symptom questionnaires at the end of each pacing period. At the end of the study, patients chose their preferred pacing period.Results. DM was significantly better than VR mode objectively (exercise time DM 8.1 min, VR 7.0 min, p < 0.01) and subjectively (perceived well-being DM 69, VR 51, p < 0.001; functional class DM 2.2, VR 2.5, p < 0.05; subjective symptom score DM 21.2, VR 26.8, p = 0.01). Patient-perceived well-being was significantly better with DM than with DR mode (DM 69, DR 60, p = 0.02). DM mode was the preferred pacing period (DM 51%, DR 14%, VR 14%). Early termination of pacing because of adverse symptoms was requested by 33% of patients during VR, 19% during DR but only 3% during DM mode. A higher proportion of patients with a fast mode-switching device preferred DM mode (fast 55%, slow 49%), whereas no patients with a fast mode-switching device chose VR as the preferred mode (fast 0%, slow 19%). In the subgroup of patients who had had atrioventricular node ablation, DM was also preferred to VR mode (DM 53%, VR 27%). Overall, there were only two cases of inappropriate mode switching and one case of inappropriate tracking of an atrial tachyarrhythmia.Conclusions. DM is the pacing mode of choice of patients with paroxysmal atrial tachyarrhythmias. With optimal programming, inappropriate mode switching and tracking of atrial tachyarrthmias was very uncommon

Effect of Arteriovenous Anastomosis on Blood Pressure Reduction in Patients With Isolated Systolic Hypertension Compared With Combined Hypertension

Background: Options for interventional therapy to lower blood pressure (BP) in patients with treatment‐resistant hypertension include renal denervation and the creation of an arteriovenous anastomosis using the ROX coupler. It has been shown that BP response after renal denervation is greater in patients with combined hypertension (CH) than in patients with isolated systolic hypertension (ISH). We analyzed the effect of ROX coupler implantation in patients with CH as compared with ISH. Methods and Results: The randomized, controlled, prospective ROX Control Hypertension Study included patients with true treatment‐resistant hypertension (office systolic BP ≥140 mm Hg, average daytime ambulatory BP ≥135/85 mm Hg, and treatment with ≥3 antihypertensive drugs including a diuretic). In a post hoc analysis, we stratified patients with CH (n=31) and ISH (n=11). Baseline office systolic BP (177±18 mm Hg versus 169±17 mm Hg, P=0.163) and 24‐hour ambulatory systolic BP (159±16 mm Hg versus 154±11 mm Hg, P=0.463) did not differ between patients with CH and those with ISH. ROX coupler implementation resulted in a significant reduction in office systolic BP (CH: −29±21 mm Hg versus ISH: −22±31 mm Hg, P=0.445) and 24‐hour ambulatory systolic BP (CH: −14±20 mm Hg versus ISH: −13±15 mm Hg, P=0.672), without significant differences between the two groups. The responder rate (office systolic BP reduction ≥10 mm Hg) after 6 months was not different (CH: 81% versus ISH: 82%, P=0.932). Conclusions: Our data suggest that creation of an arteriovenous anastomosis using the ROX coupler system leads to a similar reduction of office and 24‐hour ambulatory systolic BP in patients with combined and isolated systolic hypertension. Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01642498

Modern pacemaker modes and everyday activity

In recent years there has been a rapid evolution in pacemaker technology resulting in more `physiological' devices with increasingly complex features designed to improve patient wellbeing during everyday living. Studies described in this thesis assess, subjectively and objectively, the function of different rate response sensors, different programming parameters and different modern rate responsive pacing modes during everyday activity. The chronotropic response of patients with four types of single chamber (VVIR) pacemaker was adequate during treadmill exercise tests but poor during everyday activities involving burst and resting stress. Dual chamber devices were clearly superior during everyday activity. Programming and assessment of new and current rate adaptive devices should additionally use standardised daily activities to better simulate response during everyday activity. Holter monitor analysis of VVIR pacing during everyday activity showed that the known advantages of this mode over fixed rate (VVI) pacing result from increased rate pacing for less than 15&#37; of the day. The effect of malprogramming of dual (DDDR), and single (VVIR) chamber rate responsive pacemakers reveals that patients find over-programming least acceptable but objective exercise tolerance is not significantly affected as long as some pacemaker rate response is available. The effect of different atrioventricular delay programming in DDDR mode shows that rate adaptive and shorter fixed settings are preferable to longer ones (250 ms). There was no difference in objective exercise tolerance but echocardiography revealed decreased stroke distance at 250 ms at high paced rates. Double blind crossover comparison of VVIR, DDIR, DDD and DDDR modes during out of hospital activity found that DDDR was most and VVIR least acceptable, with objective improvements detected in DDDR over all the remaining modes. Change in stroke volume detected by echo-Doppler proved predictive of benefit from dual chamber rate responsive pacing. Three echocardiographic techniques were compared to gated radionuclide ventriculography during assessment of modern pacing modes. Continuous wave Doppler proved most sensitive and reproducible in serial studies whilst nuclear scintigraphy failed to demonstrate beat to beat haemodynamic changes or to distinguish between different modes at rest or during exercise. The effect of upgrading apparently asymptomatic patients paced in VVI mode to DDD pacing has demonstrated the existence of a `subclinical' pacemaker syndrome in nearly 70&#37; of such patients. This study suggests that DDD mode pacing should be used whenever possible. The increasing sophistication of modern pacemakers does result in improved patient wellbeing during everyday activity.</p

A randomized double-blind crossover comparison of four rate-responsive pacing modes

The aim of this study was to compare, both subjectively and objectively, four modern rate-responsive pacing modes in a double-blind crossover design. Twenty-two patients, aged 18 to 81 years, had an activity-sensing dual chamber universal rate-responsive (DDDR) pacemaker implanted for treatment of high grade atrioventricular block and chronotropic incompetence. They were randomly programmed to WIR (ventricular demand rate-responsive), DDIR (dual chamber demand rate-responsive), DDD (dual chamber universal) or DDDR (dual chamber universal rate-responsive) mode and assessed after 4 weeks of out-of-hospital activity.Five patients, all with WIR pacing, requested early reprogramming. The DDDR mode was preferred by 59% of patients; the WIR mode was the least acceptable mode in 73%. Perceived “general well-being,” exercise capacity, functional status and symptoms were significantly worse in the WIR than in dual rate-responsive modes. Exercise treadmill time was longer in DDDR mode (p < 0.01), but similar in all other modes. During standardized daily activities, heart rate in WIR and DDIR modes underresponded to mental stress. All rate-augmented modes overresponded to staircase descent, whereas the DDD mode significantly underresponded to staircase ascent.Echocardiography revealed no difference in chamber dimensions, left ventricular fractional shortening or pulmonary artery pressure in any mode. Cardiac output was greater at rest in the dual modes than in the WIR mode (p = 0.006) but was similar at 120 beats/min. Beat to beat variability of cardiac output was greatest in WIR mode (p < 0.0001), with DDIR showing greater variability than DDD or DDDR modes (p < 0.05). Mitral regurgitation estimated by Doppler color flow imaging was similar in all modes, but tricuspid regurgitation was significantly greater in WIR than in dual modes (p < 0.03).Subjects who preferred the DDDR mode and those who found the WIR mode least acceptable had significantly greater increases in stroke volume when paced in the DDD mode than in the ventricular-inhibited (WI) mode at rest (22%) when compared with subjects who preferred other modes (2%, p = 0.03). No other objective variable was predictive of subjective benefit from any rate-responsive pacing mode. Thus, dual sensor rate-responsive pacing (DDDR) is superior objectively and subjectively to single sensor (WIR, DDIR and DDD) pacing and subjective benefit from dual chamber rate-augmented pacing is predictable echocardiographically