Improvement of cardiac function by increasing stimulus strength during left ventricular pacing in cardiac resynchronization therapy.

Cardiac resynchronization therapy (CRT) is an established therapy in patients with severe heart failure due to left ventricular (LV) dyssynchrony. Increasing stimulus strength (SS) of LV pacing could capture an enlarged myocardial area and provide rapid electrical conduction. The aim of the present study was to investigate whether increasing SS of LV pacing improves LV mechanical dyssynchrony and cardiac function in patients treated with CRT.

Effect of atorvastatin therapy on fibrous cap thickness in coronary atherosclerotic plaque as assessed by optical coherence tomography: the EASY-FIT study.

Background: The detailed mechanism of plaque stabilization by statin therapy is not fully understood.

Objectives: The aim of this study was to assess the effect of lipid-lowering therapy with 20 mg/day of atorvastatin versus 5 mg/day of atorvastatin on fibrous cap thickness in coronary atherosclerotic plaques by using optical coherence tomography (OCT).

Methods: Seventy patients with unstable angina pectoris and untreated dyslipidemia were randomized to either 20 mg/day or 5 mg/day of atorvastatin therapy.

Determination of culprit coronary artery branches using hemodynamic indices from angiographic images.

A recently reported angiographic technique for hemodynamic indices based on first-pass distribution analysis (FPA) could potentially be helpful for determining the culprit artery responsible for myocardial ischemia. The purpose of this study was to determinate the culprit coronary arterial branches based on coronary flow reserve (CFR) and fractional flow reserve (FFR) using only angiographic images. The study was performed in 14 anesthetized swine.

End-diastolic fractional flow reserve: comparison with conventional full-cardiac cycle fractional flow reserve.

Background: Diastolic fractional flow reserve (dFFR) has been shown to be highly sensitive for detection of inducible myocardial ischemia. However, its reliance on measurement of left-ventricular pressure for zero-flow pressure correction, as well as manual extraction of the diastolic interval, has been its major limitation. Given previous reports of minimal zero-flow pressure at end-diastole, we compared instantaneous ECG-gated end-diastolic FFR with conventional full-cardiac cycle FFR and other diastolic indices in the porcine model.

Acceleration time of systolic coronary flow velocity to diagnose coronary stenosis in patients with microvascular dysfunction.

Background: The aim of this study was to test whether acceleration time of systolic coronary flow velocity could contribute to the diagnosis of coronary stenosis in patients with microvascular dysfunction, on the basis of the hypothesis that systolic coronary flow is less influenced by microvascular function because of compressed myocardium.

Methods: Coronary flow velocity was assessed in the left anterior descending coronary artery during hyperemia with intravenous adenosine by echocardiography in 502 patients who were scheduled for coronary angiography because of coronary artery disease and significant valvular disease. Coronary flow velocity reserve (CFVR) and the percentage acceleration time (%AT), as the percentage of the time from the beginning to the peak of systolic coronary flow over systolic time during hyperemia, were calculated.

Coronary superficial and spotty calcium deposits in culprit coronary lesions of acute coronary syndrome as determined by optical coherence tomography.

The characteristics of coronary artery calcium responsible for vulnerable plaque remain incompletely elucidated. We used optical coherence tomography to investigate the characteristics of coronary calcium in acute myocardial infarction (AMI), unstable angina pectoris (UAP), and stable angina pectoris (SAP). We evaluated calcium deposits in the culprit lesions (30-mm segment) using optical coherence tomography in 187 patients with AMI (n = 44), UAP (n = 73), or SAP (n = 70).

Clinical significance of low signal intensity area surrounding stent struts identified by optical coherence tomography.

Previous intravascular ultrasound studies have shown that echolucent neointimal hyperplasia occasionally appears after bare-metal stent (BMS) or sirolimus-eluting stent (SES) implantation. Optical coherence tomography (OCT) studies have also demonstrated that paclitaxel-eluting stent (PES) restenosis exhibited similar images showing low signal intensity areas (LSIA) surrounding stent struts and three-layer appearance (TLA). The aim of the present study was to investigate the clinical significance of LSIA on OCT images in various types of stents.

Altered coronary flow velocity reserve and left ventricular wall motion dynamics: a phenomenon in hypertensive patients with ECG strain.

Background: The inner-half layer of the left ventricular (LV) wall is primarily affected by ischemia and increased LV afterload. We hypothesized that LV wall thickening of inner-half layer and coronary microvascular function are impaired in hypertensive patients, especially in those with electrocardiographic (ECG) strain, which is a marker of LV hypertrophy and adverse prognosis. Therefore, the aim of this study is to investigate the association of the ratio of inner- to outer-half layer of the LV myocardial deformation and coronary microvascular function with ECG strain in hypertensive patients.

An angiographic technique for coronary fractional flow reserve measurement: in vivo validation.

Fractional flow reserve (FFR) is an important prognostic determinant in a clinical setting. However, its measurement currently requires the use of invasive pressure wire, while an angiographic technique based on first-pass distribution analysis and scaling laws can be used to measure FFR using only image data. Eight anesthetized swine were instrumented with flow probe on the proximal segment of the left anterior descending (LAD) coronary arteries.

Quantification of absolute coronary flow reserve and relative fractional flow reserve in a swine animal model using angiographic image data.

Coronary flow reserve (CFR) and fractional flow reserve (FFR) are important physiological indexes for coronary disease. The purpose of this study was to validate the CFR and FFR measurement techniques using only angiographic image data. Fifteen swine were instrumented with an ultrasound flow probe on the left anterior descending artery (LAD).

Effect of strut thickness on neointimal atherosclerotic change over an extended follow-up period (≥ 4 years) after bare-metal stent implantation: intracoronary optical coherence tomography examination.

Background: Neointima inside the bare-metal stents (BMSs) can transform into atherosclerotic tissue during an extended follow-up because of a persistent inflammatory reaction to the metal. We sought to investigate whether strut thickness may impact on the atherosclerotic change in neointima 4 years or more after BMS implantation using optical coherence tomography.

Methods: Forty-six stented lesions of 41 patients with BMS ≥ 4 years after implantation who underwent optical coherence tomography were enrolled in the study.

Comparison of contrast media and low-molecular-weight dextran for frequency-domain optical coherence tomography.

Background: Although an intracoronary frequency-domain optical coherence tomography (FD-OCT) system overcomes several limitations of the time-domain OCT (TD-OCT) system, the former requires injection of contrast media for image acquisition. The increased total amount of contrast media for FD-OCT image acquisition may lead to the impairment of renal function. The safety and usefulness of the non-occlusion method with low-molecular-weight dextran L (LMD-L) via a guiding catheter for TD-OCT image acquisition have been reported previously.

Conformational change in coronary artery structure assessed by optical coherence tomography in patients with vasospastic angina.

Objectives: The aim of this study was to investigate the conformational change of arterial structure in the vasospastic lesion with optical coherence tomography.

Background: Coronary artery spasm plays an important role in the pathogenesis of ischemic heart diseases. The conformational change of each arterial layer during vasospasm has not been studied in detail.

Thin-cap fibroatheroma as high-risk plaque for microvascular obstruction in patients with acute coronary syndrome.

Background: Plaque contents can cause microvascular impairment, which is an important determinant of clinical outcomes in patients with acute coronary syndrome (ACS). We hypothesized that percutaneous coronary intervention (PCI) for thin-cap fibroatheroma (TCFA) could easily disrupt the fibrous cap and expose the contents of plaque to coronary flow, possibly resulting in microvascular obstruction (MVO). The purpose of this study was to investigate whether TCFA was associated with MVO after PCI in patients with ACS.

Impact of hinge motion on in-stent restenosis after sirolimus-eluting stent implantation.

Background: A tortuous lesion with hinge motion is reportedly a risk factor for in-stent restenosis (ISR) after bare metal stent implantation. Sirolimus-eluting stents (SESs) implantation has dramatically reduced ISR. However, SES is a closed-cell design stent, which has low conformability and flexibility.

Assessment of coronary microcirculation in a swine animal model.

Coronary microvascular dysfunction has important prognostic implications. Several hemodynamic indexes, such as coronary flow reserve (CFR), microvascular resistance, and zero-flow pressure (P(zf)), were used to establish the most reliable index to assess coronary microcirculation. Fifteen swine were instrumented with a flow probe, and a pressure wire was advanced into the distal left anterior descending artery.

Quantification of coronary microvascular resistance using angiographic images for volumetric blood flow measurement: in vivo validation.

Structural coronary microcirculation abnormalities are important prognostic determinants in clinical settings. However, an assessment of microvascular resistance (MR) requires a velocity wire. A first-pass distribution analysis technique to measure volumetric blood flow has been previously validated.

Difference of culprit lesion morphologies between ST-segment elevation myocardial infarction and non-ST-segment elevation acute coronary syndrome: an optical coherence tomography study.

Objectives: The aim of this study was to investigate the difference of culprit lesion morphologies assessed by optical coherence tomography (OCT) between ST-segment elevation myocardial infarction (STEMI) and non-ST-segment elevation acute coronary syndrome (NSTEACS).

Background: Autopsy studies have reported that rupture of a thin-cap fibroatheroma and subsequent thrombus formation is the most important mechanism leading to acute coronary syndrome (ACS). Optical coherence tomography is a high-resolution imaging modality that is capable of investigating detailed coronary plaque morphology in vivo.

Prevalence and clinical significance of papillary muscle infarction detected by late gadolinium-enhanced magnetic resonance imaging in patients with ST-segment elevation myocardial infarction.

Background: The frequency of papillary muscle infarction (PapMI) without rupture has not been fully investigated in vivo. Furthermore, the relationship between papillary muscle dysfunction and mitral regurgitation (MR) has been controversial in patients with ST-segment elevation myocardial infarction. Therefore, the aim of this study was to assess the frequency and clinical characteristics of PapMI without rupture using late gadolinium-enhanced magnetic resonance imaging (MRI) in patients with ST-segment elevation myocardial infarction.

Serial angiographic findings and prognosis of stent fracture site without early restenosis after sirolimus-eluting stent implantation.

Background: Stent fracture is one of the possible causes of in-stent restenosis after sirolimus-eluting stent (SES) implantation. However, long-term prognosis including late restenosis in stent fracture site without early restenosis remains unknown. The aim of this study is to investigate the risk of late restenosis at the stent fracture site without early restenosis after SES implantation.

Advantage of right ventricular outflow tract pacing on cardiac function and coronary circulation in comparison with right ventricular apex pacing.

Background: The purpose of this study was to investigate the acute effect of right ventricular outflow tract (RVOT) pacing and right ventricular apex (RVA) pacing on synchronous ventricular activation and coronary flow dynamics.

Methods: We enrolled 20 consecutive patients who underwent electrophysiologic study. Echocardiographic study including two-dimensional tissue tracking imaging and Doppler guide wire examination was performed during RVOT pacing and RVA pacing.