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Fletcher A Miller

Publications and source records attributed to Fletcher A Miller.

11 recordsLinked to original sources
PubMed2006

Usefulness of two-dimensional speckle strain for evaluation of left ventricular diastolic deformation in patients with coronary artery disease.

We investigated the influence of > or =70% luminal coronary artery stenosis on regional diastolic deformation at rest using 2-dimensional strain echocardiography. We prospectively imaged patients during/within 24 hours of coronary angiography. Longitudinal systolic (SRs), early (SRe), and late diastolic strain rates, systolic, early, and late diastolic strain and times to isovolumic relaxation and peak SRe were measured in the 3 major vascular territories. Regions subtended by > or =70% coronary stenosis were labeled ischemic. Ischemic regions were compared with the same region in patients without significant coronary stenosis. Of 61 enrolled patients (38 men), 39 had > or =70% coronary stenosis (1 vessel in 14, 2 vessels in 15, 3 vessels in 10), and 15 had normal coronary arteries. There were no significant differences between the normal and ischemic groups with regard to age (59 +/- 13 vs 64 +/- 10 years, p = 0.20), clinical variables (dyslipidemia, smoking, diabetes), systolic (130 +/- 26 vs 139 +/- 31 mm Hg, p = 0.38) or diastolic (72 +/- 13 vs 72 +/- 11 mm Hg, p = 0.81) blood pressure and ejection fraction (58 +/- 12% vs 56 +/- 11%, p = 0.66). SRs and SRe were significantly decreased in ischemic compared with normal regions in all vascular distributions. SRs and SRe together (values below cutoff) or SRe alone were the most specific (93%) and SRe or SRs below cutoff the most sensitive (93%) parameters for detecting ischemic regions. In conclusion, analysis of regional deformation by 2-dimensional strain echocardiography enables detection of significantly diseased coronary arteries at rest. Altered diastolic deformation at rest identifies regions subtended by > or =70% coronary stenosis with high specificity.

Coronary Artery Disease↗
PubMed2006

Comparison of usefulness of echocardiographic Doppler variables to left ventricular end-diastolic pressure in predicting future heart failure events.

We sought to determine whether the echocardiographic Doppler parameters of left ventricular diastolic dysfunction predict future heart failure (HF) events and, if so, which parameters best predict HF. We also examined whether the predictive ability of echocardiographic Doppler parameters was related to their prediction of left ventricular end-diastolic pressure (LVEDP). We studied patients who underwent cardiac catheterization and echocardiography performed within a 30-day period. The end point was HF, defined as new-onset or recurrent HF diagnosed by a physician and requiring the initiation or modification of treatment of HF. We identified 289 patients (mean age 63.5 +/- 12.6 years) with a mean follow-up of 10.9 +/- 10.2 months. A total of 24 HF events occurred. LVEDP was a significant predictor of HF univariately and independently in multiple regression models after adjustment for ejection fraction. In Cox models adjusted for age, gender, LVEDP, and ejection fraction, only the left atrial volume index and early mitral inflow to early diastolic tissue velocity (E/e') ratio remained predictive of HF. A multiple regression model, including all echocardiographic variables, showed a persistent, although attenuated, relation of early to late mitral inflow velocity (E/A) ratio and E/e' with LVEDP (p = 0.06 and p = 0.002, respectively). The addition of E/e' or the left atrial volume indexed to body surface area, but not E/A, to the clinical history and left ventricular ejection fraction provided incremental prognostic information. A LVEDP of > or =20 mm Hg, E/e' ratio of > or =15, and left atrial volume index of > or =23 ml/m(2) identified those with a higher risk of HF. In conclusion, invasively determined LVEDP is an independent predictor of future HF events. E/e' and the left atrial volume indexed to body surface area are the best independent predictors of future HF and provide prognostic information incremental to the clinical history and left ventricular ejection fraction.

Adult↗
PubMed2006

Impact of prosthesis-patient mismatch on long-term survival in patients with small St Jude Medical mechanical prostheses in the aortic position.

BACKGROUND: The impact of aortic prosthesis-patient mismatch (P-PtM) on long-term survival is unclear. METHODS AND RESULTS: Between 1985 and 2000, 388 patients at Mayo Clinic in Rochester, Minn, underwent aortic valve replacement (AVR) with 19- or 21-mm St Jude Medical prostheses and had transthoracic echocardiography within 1 year after AVR. Mean age of patients was 62+/-13 years; 69% were female. Prosthesis effective orifice area (EOA) was derived from the continuity equation. P-PtM was classified as severe (indexed EOA < or =0.60 cm2/m2), moderate (0.60 cm2/m2 0.85 cm2/m2). P-PtM was severe in 66 patients (17%), moderate in 168 (43%), and not hemodynamically significant in 154 (40%). Patients with severe P-PtM had a significantly larger body surface area (P<0.0001), higher mean gradient (P<0.0001), lower preoperative (P<0.0001) and postoperative (P<0.0001) ejection fractions, and lower stroke volume (P<0.0001) and more often received a 19-mm prosthesis (P=0.0008) than patients with moderate or no hemodynamically significant mismatch. For patients with severe mismatch, 5-year survival rates (72+/-6%) and 8-year survival rates (41+/-8%) were significantly less than for patients with moderate mismatch (80+/-3% and 65+/-5%; P=0.026) or no hemodynamically significant mismatch (85+/-3% and 74+/-5%; P=0.002). On multivariate analysis after adjustment for other predictors of outcome, severe mismatch was associated with higher mortality (hazard ratio 2.18; 95% confidence interval 1.24 to 3.85; P=0.007) and higher incidence of congestive heart failure (hazard ratio 3.1; 95% confidence interval 1.3 to 7.4; P=0.009) than no hemodynamically significant mismatch. CONCLUSIONS: Severe P-PtM is an independent predictor of higher long-term mortality and congestive heart failure in patients with small St Jude Medical aortic valve prostheses. For patients undergoing AVR who are at risk of severe mismatch, every effort should be made to use a larger prosthesis or to consider a prosthesis with a larger EOA.

Aged↗
PubMed2006

Right ventricular function in asymptomatic individuals with a systemic right ventricle.

BACKGROUND: In congenital heart defects where the morphologic right ventricle (RV) supports the systemic circulation, RV failure is common yet develops gradually. We hypothesized that patients who are asymptomatic may have unrecognized RV dysfunction. METHODS: Conventional and Doppler tissue/strain echocardiography were performed on consecutive patients with asymptomatic systemic RV caused by congenitally corrected transposition of the great arteries (ccTGA) and on age-matched control subjects. RV index of myocardial performance was measured using conventional echocardiography. Longitudinal tissue velocities, strain rate, and strain of the basal RV free wall were measured using Doppler tissue/strain echocardiography and compared with nonsystemic RV of the control subjects. RESULTS: Mean age was 39.5 +/- 14.6 (n = 13) and 36 +/- 24 (n = 10) years for ccTGA and control groups, respectively. Mean RV index of myocardial performance was higher in patients with ccTGA than in control subjects (0.66 +/- 0.25 vs 0.28 +/- 0.12, P < .001). Mean RV tissue displacement (10.8 +/- 4.5 vs 20.3 +/- 3.9 mm, P < .0001), peak systolic strain rate (-1.16 +/- 0.3 vs -2.23 +/- 0.9 s(-1), P = .005), and peak systolic strain (-17.3 +/- 8.0 vs -30.6 +/- 11.0%, P = .008) were significantly lower in patients with ccTGA compared with control subjects, respectively. CONCLUSION: Patients with asymptomatic ccTGA have quantifiable RV dysfunction by echocardiography.

Adult↗
PubMed2006

Effects of pulmonary thromboendarterectomy on right-sided echocardiographic parameters in patients with chronic thromboembolic pulmonary hypertension.

OBJECTIVE: To determine the echocardiographic changes in the heart at 3 months and 1 year after pulmonary thromboendarterectomy (PTE) in patients with chronic thromboembolic pulmonary hypertension (CTEPH). PATIENTS AND METHODS: Thirty-two adult patients who underwent PTE for CTEPH at the Mayo Clinic in Rochester, Minn, from 1997 to 2003 were included in the study. All underwent transthoracic echocardiography before surgery. Follow-up echocardiography was performed within 3 months of surgery in 28 patients and 1 year postoperatively in 17 patients. The results were compared with baseline data. RESULTS: Within 3 months after PTE, the right ventricular end-diastolic area decreased from 38.4 +/- 12.8 cm2 to 32.5 +/- 10.4 cm2 (mean difference, 5.8 +/- 10.4 cm2; P = .02). The right ventricular end-systolic area decreased from 30.4 +/- 12.1 cm2 to 24.1 +/- 8.6 cm2 (mean difference, 6.3 +/- 10.1 cm2; P = .008). The right ventricular systolic pressure decreased significantly from 92.6 +/- 22.0 mm Hg to 55.0 +/- 19.8 mm Hg (mean difference, 40.0 +/- 24.8 mm Hg; P < .001). Tricuspid regurgitation (TR) improved from a mean grade of 2.5 +/- 1.2 to 1.2 +/- 1.1 (mean difference, 1.5 +/- 1.0; P < .001). At 12 months, the right ventricular end-diastolic area, right ventricular end-systolic area, right ventricular systolic pressure, and TR also were significantly lower than baseline values. CONCLUSION: In patients with CTEPH who undergo PTE, echocardiographic measurements of right ventricular size, systolic pressure, and TR show significant improvement immediately after surgery, which is sustained for up to 1 year after surgery.

Adult↗
PubMed2005

Doppler echocardiography of 119 normal-functioning St Jude Medical mitral valve prostheses: a comprehensive assessment including time-velocity integral ratio and prosthesis performance index.

The purpose of this study was to provide, in a large number of patients, comprehensive Doppler echocardiographic assessment of normal St Jude Medical mitral valve prosthesis function using Doppler-derived hemodynamic variables, including the mitral valve prosthesis-to-left ventricular outflow tract time-velocity integral ratio and prosthesis performance index. The pressure half-time was less than 130 milliseconds in all patients, and all but one patient had either a peak early mitral diastolic velocity of 2 m/s or less or a mitral valve prosthesis-to-left ventricular outflow tract time-velocity integral ratio of less than 2.2. There was a significant (P < .001) negative correlation between the prosthesis performance index and prosthesis size. This negative correlation suggests that there is more efficient use of the in vitro geometric orifice area with smaller prostheses.

Adolescent↗
PubMed2005

Doppler echocardiography of normal Starr-Edwards mitral prostheses: a comprehensive function assessment including continuity equation and time-velocity integral ratio.

The purpose of this study was to provide comprehensive Doppler echocardiographic assessment of the function of the normal Starr-Edwards mitral valve prosthesis using all the Doppler hemodynamic variables described to date, including the mitral valve prosthesis time-velocity integral (TVI)/left ventricular outflow tract TVI ratio and the prosthesis performance index. All patients had a peak early mitral diastolic velocity of no more than 2 m/s or a pressure half-time that was less than 130 milliseconds. All but one patient had either a peak early mitral diastolic velocity of no more than 2 m/s or a mitral valve prosthesis TVI/left ventricular outflow tract TVI ratio of less than 2.2, regardless of prosthesis size or left ventricular systolic function. There was a trend of decreasing prosthesis performance index with increasing prosthesis valve size that was not statistically significant, however.

Adult↗
PubMed2002

Intracardiac phased-array imaging: methods and initial clinical experience with high resolution, under blood visualization: initial experience with intracardiac phased-array ultrasound.

OBJECTIVES: This study was designed to test the feasibility of high-resolution phased-array intracardiac imaging. BACKGROUND: Intracardiac echocardiographic imaging of the heart during interventional electrophysiologic (EP) procedures has been limited by inadequate ultrasound penetration and absence of Doppler hemodynamic and flow information produced by rotating mechanical ultrasound elements. METHODS: A 10F (3.2 mm) phased-array, variable 5.5 to 10 MHz frequency imaging catheter with a four-way deflectable tip was applied in 24 patients undergoing EP studies. Sixteen prespecified cardiac targets were imaged from a right heart venue. RESULTS: Fifteen patients had no underlying organic heart disease; nine had ischemic, cardiomyopathic, valvular or congenital heart disorders. Longitudinal and short-axis imaging readily disclosed each cardiac valve, support structures and chamber, as well as the pericardium, right and left atrial appendages, the junction of the right atrium and superior vena cava, crista terminalis, tricuspid valve isthmus, coronary sinus orifice, membranous fossa ovalis and pulmonary veins. The average target depth was 8.8+/-1.5 cm (range 0.5 to 15 cm), with adequate penetration at a 7.5 MHz imaging frequency. Color flow and Doppler utilities clearly characterized transaortic and pulmonic valve and pulmonary vein blood flow, including during low output states. CONCLUSIONS: These first human studies with this technology demonstrate the methods, feasibility and utility of intracardiac phased-array vector and Doppler imaging for long-axis, apex-to-base global cardiac imaging. High resolution of endocardial structures and catheters suggests additional utility for visualizing interventional procedures from the right heart.

Arrhythmias, Cardiac↗