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Cardiac resynchronisation therapy (CRT) is a widely-performedstandard treatment for improving cardiac function and quality of life in patients with heart failure.1 After CRT, however, 30-40 % of patients do not experience improvements in left ventricular (LV) function and clinical symptoms. [2][3] The key factors for increasing the response rate to CRT are identification of the optimal LV lead position and accurate lead placement at the optimal site.
4-7The optimal LV lead position is in the viable myocardial region with the latest contraction onset. [8][9] Several myocardial imaging techniques have been developed to identify this position, such as echocardiography, [10][11] cardiac magnetic resonance imaging (CMR) 12 and nuclear imaging.
13-15Placing the LV lead in the recommended position through coronary veins is a challenge. 16,17 This procedure requires high accuracy, since a difference of 20 mm in LV lead location on the myocardial wall can influence CRT response, and an incorrect LV lead pacing site may lead to greater myocardial dyssynchrony.
18This paper reviews the technical advances and clinical studies being used in image-guided LV lead placement in CRT, including the identification of optimal LV lead position and placement of the LV lead at the recommended site.
Image-guided LV Lead Placement in CRT
Optimal LV Lead PositionMyocardial viability at the LV lead position is a key factor in enhancing CRT response rate. that the U-shaped activation pattern induced by true LBBB and a QRS duration of ≥120 ms could be used as criteria to predict CRT response.Pacing the latest mechanical activated site may significantly reduce the total LV electromechanical activation time compared with pacing other sites on the myocardial wall. 17 An animal study demonstrated that the regions with maximal resynchronisation after CRT had maximum improvements in systolic LV function. These regions are the 'sweet spots' and regarded as optimal regions for LV lead placement.
33,34A recent study shows that the latest activated regions may vary
AbstractCardiac resynchronisation therapy (CRT) is a standard treatment for patients with heart failure; however, the low response rate significantly reduces its cost-effectiveness. A favourable CRT response primarily depends on whether implanters can identify the optimal left ventricular (LV) lead position and accurately place the lead at the recommended site. Myocardial imaging techniques, including echocardiography, cardiac magnetic resonance imaging and nuclear imaging, have been used to assess LV myocardial viability and mechanical dyssynchrony, and deduce the optimal LV lead position. The optimal position, presented as a segment of the myocardial wall, is then overlaid with images of the coronary veins from fluoroscopy to aid navigation of the LV lead to the target venous site. Once validated by large clinical trials, these image-guided techniques for CRT lead placement may have an impact on current clinical practice.