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- Boriani, Giuseppe, et al.
(författare)
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Plateau waveform shape allows a much higher patient shock energy tolerance in AF patients.
- 2007
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Ingår i: Journal of cardiovascular electrophysiology. - : Wiley. - 1540-8167 .- 1045-3873. ; 18:7, s. 728-34
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- OBJECTIVES: To evaluate the possible pain reduction of the plateau waveform in atrial fibrillation (AF) patients. BACKGROUND: Previous studies have indicated that reduced amplitude waveforms would be less painful than a conventional (65/65% tilt) biphasic waveform. Computer modeling suggested that a moderately long (10-12 msec) plateau (flat topped) shock waveform would deliver equivalent effectiveness with the lowest possible peak amplitude. METHODS: We enrolled 27 patients at two sites with persistent AF with a total of 220 shocks delivered during internal atrial cardioversion using an interleaved crossover design. Patient response was scored in three ways: (1) a verbally reported discomfort score, (2) visual analog scale (VAS), and (3) a blinded observer reporting a contraction score. RESULTS: All scores were significantly reduced (P < 0.0001) by the plateau waveform with impressive statistics: Verbal discomfort (3.51 +/- 0.13 to 2.89 +/- 0.12), VAS (7.00 +/- 0.56 to 5.91 +/- 0.36), and contraction scores (1.94 +/- 0.12 to 1.62 +/- 0.12). The average pain threshold shift (TS) for the Verbal score was 2.34, while that for the VAS score was 2.30. (This means that the patient typically could tolerate 2.34 times as much energy with the plateau waveform for the same level of verbally reported discomfort.) The contraction TS was less at 1.57. Response scores were also corrected for the shock sequence number to control for the sensitization effect from multiple shocks. This increased the TS for the Verbal score to 3.58, but the shock number was not significant for the VAS. A pulmonary artery electrode return was associated with lower pain compared with a coronary sinus position. CONCLUSION: A plateau shaped biphasic waveform resulted in significantly increased shock energy pain tolerances. Controlling for session sensitization, patients tolerated over three times as much energy for the same verbally reported discomfort score.
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| 2. |
- Valzania, Cinzia, et al.
(författare)
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Effects of cardiac resynchronization therapy on coronary blood flow : Evaluation by transthoracic Doppler echocardiography
- 2008
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Ingår i: European Journal of Heart Failure. - : Wiley. - 1388-9842 .- 1879-0844. ; 10:5, s. 514-520
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Tidskriftsartikel (refereegranskat)abstract
- Background: Relatively limited and conflicting data are available on the effects of cardiac resynchronization therapy (CRT) on coronary blood flow (CBF). Aims: To investigate changes in the left anterior descending coronary artery (LAD) flow under different CRT pacing modes by means of transthoracic Doppler echocardiography (TTE). Methods: Twenty-two responders to CRT (67 11 years) with idiopathic dilated cardiomyopathy underwent TTE assessment of LAD flow and Tissue Velocity Imaging during 4 programming modes: intrinsic conduction (IC), right ventricular pacing (RV), simultaneous biventricular pacing (BVP), BVP with left ventricular (LV) pre-activation. Results: Mean coronary flow velocity (CFV) was increased by simultaneous BVP (p = 0.0063 vs. IC) and BVP with LV pre-activation (p<0.0001 vs. IC; p=0.027 vs. simultaneous BVP). Peak CFV and LAD flow velocity/time integral were highest during BVP with LV pre-activation. A reduction in septal-to-lateral delay and an increase in peak systolic velocity in the basal septum were observed during simultaneous BVP and BVP with LV pre-activation. Conclusions: In CRT responders with idiopathic dilated cardiomyopathy, an increase in LAD flow, assessed by TTE, was observed during simultaneous BVP and BVP with LV pre-activation. This was associated with an improvement in regional myocardial contraction and a decrease in intraventricular dyssynchrony.
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| 3. |
- Valzania, Cinzia
(författare)
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Electromechanical effects and optimization modalities of cardiac resynchronization therapy
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background and aims: Heart failure is a major health care problem, with high morbidity and mortality rates. In recent years, cardiac resynchronization therapy (CRT) has become an established additive treatment for patients with advanced heart failure, left ventricular (LV) dysfunction, and wide QRS complex. CRT is a stimulation technique based on right ventricular (RV) and LV pacing, usually in synchrony, delivered by a pacemaker or a cardioverter-defibrillator. Significant improvements in heart failure symptoms, hospitalization rates and mortality have been documented after initiation of CRT treatment. However, to date, 20% to 30% of patients do not respond to CRT (non responders), and improved management strategies are important. This thesis explores the acute and long-term electromechanical effects of CRT at rest and during stress, and investigates novel methods for CRT optimization. Study I: Twenty-one heart failure patients, responders to CRT, were assessed by low-dose dobutamine stress echocardiography, clinical evaluation and analysis of brain natriuretic peptide at two times: during active CRT (on) and after withholding of CRT for two weeks (off). Clinical, neurohormonal and echocardiographic results were compared between on and off conditions. This short-term cessation of CRT was associated with a deterioration of LV performance and a slight clinical impairment. Conclusion: The beneficial effects of CRT on LV systolic and diastolic function, observed at rest, were sustained during dobutamine stress, and this was mainly owing to maintained improvement in inter- and intraventricular synchrony. Study II: Twenty-two heart failure patients with idiopathic dilated cardiomyopathy (without any evidence of significant coronary artery disease at previous angiography), who had successfully responded to CRT, underwent echocardiographic assessment of left anterior descending coronary artery (LAD) flow and intraventricular dyssynchrony during different pacing modes. Changes in LAD flow variables were correlated with simultaneous variations in intraventricular dyssynchrony. The mean coronary flow velocity increased by comparison with intrinsic conduction during simultaneous biventricular pacing (p = 0.0063) and biventricular pacing with LV preactivation (p < 0.0001), and was higher in the latter programming mode (p = 0.027). Conclusion: In patients with idiopathic dilated cardiomyopathy, simultaneous biventricular pacing and biventricular pacing with LV preactivation increase LAD flow, and this is associated with a reduction in intraventricular dyssynchrony. Study III Long-term variations in atrioventricular (AV) and interventricular (VV) delays were prospectively investigated in 37 heart failure patients subjected to echo-guided CRT optimization. All patients underwent CRT optimization within 48 hours of implantation and again after 6 months. Additionally, optimization at 12 months was performed in the first 14 patients enrolled. Conclusion: Echocardiographic optimization of AV and VV delays is associated with broad intraindividual variability. A new assessment of optimized VV delays during long-term follow-up reveals nonconcordance with previous values and provides a further increase in forward stroke volume. Study IV Twenty-four CRT patients were assessed both by echocardiography and by an automated intracardiac electrogram (IEGM) method with regard to optimal AV and VV delays. In addition, the acute impact of exercise CRT optimization on hemodynamic variables was investigated. Significant rest-to-exercise changes in optimal VV delay, but not in AV delay, were observed. Reassessment of optimal device programming during ongoing exercise resulted in an improvement in LV dyssynchrony and hemodynamic parameters, giving an additional benefit to that provided by optimization performed at rest. Conclusion: The IEGM method seems to be a promising alternative to the standard echocardiographic approach, both at rest and during exercise. Study V Twelve heart failure patients were evaluated for acute changes in multiple vector intracardiac impedance (ICZ) signals during implantation of a CRT device operating in different pacing modes. Bipolar (Z1) and quadripolar (Z2) impedance signals, recorded in the RV and between the LV and RV, respectively, were analyzed with respect to amplitude and systolic slope, and correlated with noninvasive hemodynamic and echocardiographic variables. The Z1 and Z2 variables correlated positively with all noninvasive hemodynamic variables and LV and RV ejection fractions, and inversely with LV and RV volumes. The Z2 systolic slope correlated with the interventricular conduction delay (r = 0.33, p < 0.05). Conclusion: Multiple vector ICZ measurement may be a feasible tool for hemodynamic assessment in patients treated with biventricular pacing. Summary: In heart failure patients, CRT has been shown to improve symptoms, exercise capacity and survival. Our findings suggest that in long-term responders, the benefits of CRT on LV synchrony and function that are observed at rest are sustained during pharmacological stress, thereby providing a link between pathophysiological mechanisms and clinical evidence of improved exercise capacity. The finding of increased LAD flow during biventricular pacing highlights a possible additional mechanism responsible for the beneficial effects of CRT. CRT optimization has been shown to provide acute hemodynamic benefits. The dynamic changes in optimal AV and VV delays during long-term follow-up and from rest to exercise suggest that reevaluations of CRT programming may be useful. Novel automated device-based algorithms seem to be a feasible alternative to echocardiography for CRT optimization. Furthermore, multiple vector ICZ measurement may be a promising tool for hemodynamic assessment and optimization in CRT patients.
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