Technical and clinical study of x-ray-based surface echo probe tracking using an attached fiducial apparatus.

PURPOSE: Several types of structural heart intervention (SHI) use information from multiple imaging modalities to complete an interventional task. For example, in transcatheter aortic valve replacement (TAVR), placement and deployment of a bioprosthetic aortic valve in the aorta is primarily guided by x-ray fluoroscopy (XRF), and echocardiography provides visualization of cardiac anatomy and blood flow. However, simultaneous interpretation of independent x-ray and echo displays remains a challenge for the interventionalist. The purpose of this work was to develop a novel echo/x-ray co-registration solution in which volumetric transthoracic echo (TTE) is transformed to the x-ray coordinate system by tracking the three-dimensional (3D) pose of a probe fiducial attachment from its appearance in two-dimensional (2D) x-ray images. METHODS: A fiducial attachment for a commercial TTE probe consisting of rings of high-contrast ball bearings was designed and fabricated. The 3D pose (position and orientation) of the fiducial attachment is estimated from a 2D x-ray image using an algorithm in which a virtual point cloud model of the attachment is iteratively rotated, translated, and forward-projected onto the image until the average sum-of-squares of grayscale values at the projected points is minimized. Fiducial registration error (FRE) and target registration error (TRE) of this approach were evaluated in phantom studies using TAVR-relevant gantry orientations and four standard acoustic windows for the TTE probe. A patient study was conducted to assess the clinical suitability of the fiducial attachment prototype during TTE imaging of patients undergoing SHI. TTE image quality for the task of guiding a transcatheter procedure was evaluated in a reviewer study. RESULTS: The 3D FRE ranged from 0.32 ± 0.03 mm (mean ± SD) to 1.31 ± 0.05 mm, depending on C-arm orientation and probe acoustic window. The 3D TRE ranged from 1.06 ± 0.03 mm to 2.42 ± 0.06 mm. Fiducial pose estimation was stable when >75% of the fiducial markers were visible in the x-ray image. A panel of reviewers graded the presentation of heart valves in TTE images from 48 SHI patients. While valve presentation did not differ significantly between acoustic windows (P > 0.05), the mitral valve did achieve a significantly higher image quality compared to the aortic and tricuspid valves (P < 0.001). Overall, reviewers perceived sufficient image quality in 76.5% of images of the mitral valve, 54.9% of images of the aortic valve, and 48.6% of images of the tricuspid valve. CONCLUSIONS: Fiducial-based tracking of a commercial TTE probe is compatible with clinical SHI workflows and yields 3D target registration error of less than 2.5 mm for a variety of x-ray gantry geometries and echo probe acoustic windows. Although TTE image quality with respect to target valve anatomy was sufficient for the majority of cases examined, prescreening of patients for sufficient TTE quality would be helpful.

Cardiorenal status using amino-terminal pro-brain natriuretic peptide and cystatin C on cardiac resynchronization therapy outcomes: From the BIOCRT Study.

BACKGROUND: Cardiorenal syndrome comprises a heterogeneous group of disorders characterized by acute or chronic cardiac and renal dysfunction. OBJECTIVE: The purpose of this study was to determine the effect of cardiorenal status using a dual-marker strategy with amino-terminal pro-brain natriuretic peptide (NT-proBNP) and cystatin C on cardiac resynchronization therapy (CRT) outcomes. METHODS: In 92 patients (age 66 ± 13 years; 80% male; left ventricular ejection fraction 26% ± 7%), NT-proBNP and cystatin C levels were measured at CRT implantation and at 1 month. NT-proBNP >1000 pg/mL and cystatin C >1 mg/L were considered high. Baseline cardiorenal patients were defined as having high NT-proBNP and cystatin C. At 1 month, CRT patients were categorized as (1) irreversible cardiorenal if cystatin C was persistently high; (2) progressive cardiorenal with transition from low to high cystatin C; (3) reversible cardiorenal with transition from high to low cystatin C; and (4) "normal" with stable low cystatin C. Outcomes were 6-month clinical and echocardiographic CRT response and 2 -year major adverse cardiovascular event (MACE). RESULTS: Compared to patients with low NT-proBNP and cystatin C, cardiorenal patients had >9-fold increase risk of CRT nonresponse (odds ratio uncompensated 9.0; compensated 36.4; both P ≤.004) and >6-fold risk of MACE (hazard ratio uncompensated 8.5; P = .005). Compared to "normal" and reversible patients (referent), irreversible patients had a 9-fold increase for CRT nonresponse (odds ratio 9.1; P <.001) and had >4-fold risk of MACE (adjusted hazard ratio 5.1; P <.001). Irreversible patients were most likely echocardiographic CRT nonresponders. CONCLUSION: Cardiorenal status by NT-proBNP and cystatin C can identify high-risk CRT patients, and those with both elevated concentrations have worse prognosis.

Incremental value of cystatin C over conventional renal metrics for predicting clinical response and outcomes in cardiac resynchronization therapy: The BIOCRT study.

BACKGROUND: Despite the benefit of CRT in select patients with heart failure (HF), there remains significant need for predicting those at risk for adverse outcomes for this effective but costly therapy. CysC, an emerging marker of renal function, is predictive of worsening symptoms and mortality in patients with HF. This study assessed the utility of baseline and serial measures of cystatin C (CysC), compared to conventional creatinine-based measures of renal function (estimated glomerular filtration rate, eGFR), in predicting clinical outcomes following cardiac resynchronization therapy (CRT). METHODS: In 133 patients, we measured peripheral venous (PV) and coronary sinus (CS) CysC concentrations and peripheral creatinine levels at the time of CRT implant. Study endpoints included clinical response to CRT at 6 months and major adverse cardiac events (MACE) at 2 years. RESULTS: While all 3 renal metrics were predictive of MACE (all adjusted p ≤ 0.02), only CysC was associated with CRT non-response at 6 months (adjusted odds ratio 3.6, p = 0.02). CysC improved prediction of CRT non-response (p ≤ 0.003) in net reclassification index analysis compared to models utilizing standard renal metrics. Serial CysC > 1mg/L was associated with 6-month CRT non-response and reduced 6-minute walk distance as well as 2-year MACE (all p ≤ 0.04). CONCLUSION: In patients undergoing CRT, CysC demonstrated incremental benefit in the prediction of CRT non-response when compared to standard metrics of renal function. Baseline and serial measures of elevated CysC were predictive of CRT non-response and functional status at 6 months as well as long-term clinical outcomes.

Analysis of ventricular function by CT.

The assessment of ventricular function, cardiac chamber dimensions, and ventricular mass is fundamental for clinical diagnosis, risk assessment, therapeutic decisions, and prognosis in patients with cardiac disease. Although cardiac CT is a noninvasive imaging technique often used for the assessment of coronary artery disease, it can also be used to obtain important data about left and right ventricular function and morphology. In this review, we will discuss the clinical indications for the use of cardiac CT for ventricular analysis, review the evidence on the assessment of ventricular function compared with existing imaging modalities such cardiac magnetic resonance imaging and echocardiography, provide a typical cardiac CT protocol for image acquisition and postprocessing for ventricular analysis, and provide step-by-step instructions to acquire multiplanar cardiac views for ventricular assessment from the standard axial, coronal, and sagittal planes. Furthermore, both qualitative and quantitative assessments of ventricular function as well as sample reporting are detailed.

Steroid exposure, acute coronary syndrome, and inflammatory bowel disease: insights into the inflammatory milieu.

BACKGROUND: Steroids are anti-inflammatory agents commonly used to treat inflammatory bowel disease. Inflammation plays a critical role in the pathophysiology of both inflammatory bowel disease and acute coronary syndrome. We examined the relationship between steroid use in patients with inflammatory bowel disease and acute coronary syndrome. METHODS: In 177 patients with inflammatory bowel disease (mean age 67 years, 75% male, 44% Crohn's disease, 56% ulcerative colitis), we performed a 1:2 case-control study matched for age, sex, and inflammatory bowel disease type, and compared 59 patients with inflammatory bowel disease with acute coronary syndrome to 118 patients with inflammatory bowel disease without acute coronary syndrome. Steroid use was defined as current or prior exposure. Acute coronary syndrome was defined as myocardial infarction or unstable angina, confirmed by cardiac biomarkers and coronary angiography. RESULTS: In patients with inflammatory bowel disease, 34% with acute coronary syndrome had exposure to steroids, vs 58% without acute coronary syndrome (P < .01). Steroid exposure reduced the adjusted odds of acute coronary syndrome by 82% (odds ratio [OR] 0.39; 95% confidence interval [CI], 0.20-0.74; adjusted OR 0.18; 95% CI, 0.06-0.51) in patients with inflammatory bowel disease, 77% in Crohn's disease (OR 0.36; 95% CI, 0.14-0.92; adjusted OR 0.23; 95% CI, 0.06-0.98), and 78% in ulcerative colitis (OR 0.41; 95% CI, 0.16-1.04; adjusted OR 0.22; 95% CI, 0.06-0.90). There was no association between other inflammatory bowel disease medications and acute coronary syndrome. CONCLUSIONS: In patients with inflammatory bowel disease, steroid use significantly reduces the odds of acute coronary syndrome. These findings provide further mechanistic insight into the inflammatory processes involved in inflammatory bowel disease and acute coronary syndrome.