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Raymond F Stainback

Publications and source records attributed to Raymond F Stainback.

10 recordsLinked to original sources
PubMed2005

Echocardiographic evaluation of the Jarvik 2000 axial-flow LVAD.

From April 2000 through September 2001, we studied 11 patients with the Jarvik 2000--a left ventricular assist device with an axial-flow pump that provides continuous blood flow--to determine the echocardiographic characteristics. All patients underwent complete echocardiographic examination, including outflow-graft flow evaluation 24 hours after implantation and each month thereafter for the duration of support. Data were obtained at each pump setting (8000-12000 rpm in 1000-rpm increments) and with the pump off. Left ventricular dimensions and shortening fraction and the duration of aortic valve systolic opening decreased as pump speed increased. Although the aortic valve remained closed at higher pump speeds, pump outflow-graft flow remained pulsatile, because of the systolic thrust of the assisted ventricle. Systolic dominance of phasic flow was more pronounced at lower pump speeds, due to normalization of the diseased heart's Starling response. When the aortic valve was closed continuously, echocardiographic contrast (indicating blood stasis) was noted in the aortic root. Because of the pump outflow graft's proximity to the chest wall, device output could be measured independently of cardiac contributions. Mean peak outflow-graft flow velocities were 0.75 +/- 0.30 m/s (systolic) and 0.41 +/- 0. 13 m/s (diastolic). When the pump was turned off briefly there was minimal regurgitation through the device into the left ventricle. This 1st echocardiographic heart function analysis of the Jarvik 2000 confirms that the device unloads the ventricle and increases cardiac output. Cardiac responses to device-speed changes can be evaluated readily with echocardiography in the early and late postoperative period.

Blood Flow Velocity↗
PubMed2004

Transesophageal echocardiography improves risk assessment of thrombolysis of prosthetic valve thrombosis: results of the international PRO-TEE registry.

OBJECTIVES: The goal of this study was to evaluate whether quantitation of thrombus burden with transesophageal echocardiography (TEE) can help risk-stratify patients undergoing thrombolysis of prosthetic valve thrombosis (PVT). BACKGROUND: Thrombolytic therapy of PVT has an unpredictable risk of embolization and complications. METHODS: An international registry of patients with suspected PVT undergoing two-dimensional/Doppler and TEE before thrombolysis was established. All TEE studies were reviewed and quantitated by a single observer blinded to all data. RESULTS: From 1985 to 2001, 107 patients (71 females; age 24 to 86 years) from 14 centers (6 in the U.S.) were identified. The majority of cases involved the mitral valve (79 mitral, 13 aortic, and 15 tricuspid). Hemodynamic success rate was achieved in 85% and was similar across valves. Overall complications were observed in 17.8%, and death in 5.6%. Predictors of complications were: New York Heart Association (NYHA) functional class, presence of shock, sinus tachycardia, hypotension, previous history of stroke, thrombus extension beyond the valve ring, and thrombus area. Multivariate analysis demonstrated that two variables were independent predictors of complications: thrombus area by TEE (odds ratio [OR] 2.41 per 1 cm2 increment, 95% confidence interval [CI] 1.12 to 5.19) and prior history of stroke (OR 4.55, 95% CI 1.35 to 15.38). A thrombus area <0.8 cm2 identified patients at lower risk for complications from thrombolysis, irrespective of NYHA functional class. CONCLUSIONS: In PVT, the thrombus size imaged with TEE is a significant independent predictor of outcome. Transesophageal echocardiography can identify low-risk groups for thrombolysis irrespective of symptom severity and is therefore recommended in the management of prosthetic valve thrombosis.

Adult↗
PubMed2004

Preclinical assessment of a trileaflet mechanical valve in the mitral position in a calf model.

BACKGROUND: The bileaflet valve is currently the mechanical replacement valve of choice. Though durable, it does not closely mimic native valve hemodynamics and remains potentially thrombogenic. METHODS: Prototype trileaflet valves (T1 and T2) were implanted in the mitral position in calves. Group I calves received either a T1 valve (n = 12) or a control bileaflet valve (n = 5); Group II, either a T2 valve (n = 7) or a control bileaflet valve (n = 5). Valve function, perivalvular leakage, and transvalvular pressure gradients were evaluated. Also, long-term prototype leaflet wear was evaluated in vivo in one Group I calf (502 days) and two Group II calves (385 and 366 days). Calves were euthanized and necropsied at study termination, and major organs weighed and examined. RESULTS: Valve function was excellent and hematologic parameters remained normal in all calves that survived to study termination. Mean peak transvalvular pressure gradients were 10 +/- 7 mm Hg for T1 valves, 6 +/- 3 mm Hg for T2 valves, and 12 +/- 4 mm Hg for bileaflet control valves. Clinically insignificant valvular regurgitation was observed in both prototypes. Explanted valves showed no thrombus-impaired leaflet motion, except in two T1-fitted calves and one T2-fitted calf. Major organs showed no evidence of clinically significant thromboembolic events. There were no other significant differences between the results of experimental and control groups. CONCLUSIONS: Prototype trileaflet valves performed safely and effectively in the mitral position in calves, even without long-term anticoagulation. This warrants their evaluation as an equivalent alternative to bileaflet valves.

Animals↗
PubMedDate not supplied

Baseline hemodynamic and echocardiographic indices in anesthetized calves.

The experimental calf model is used to assess mechanical circulatory support devices and prosthetic heart valves. Baseline indices of cardiac function have been established for the normal awake calf but not for the anesthetized calf. Therefore, we gathered hemodynamic and echocardiographic data from 16 healthy anesthetized calves (mean age, 189.0 +/- 87.0 days; mean body weight, 106.9 +/- 32.3 kg) by cardiac catheterization and noninvasive echocardiography, respectively. Baseline hemodynamic data included heart rate (65 +/- 12 beats per minute), mean aortic pressure (113.5 +/- 17.4 mm Hg), left ventricular end-diastolic pressure (16.3 +/- 38.9 mm Hg), and mean pulmonary artery pressure (21.7 +/- 8.3 mm Hg). Baseline two-dimensional echocardiographic data included left ventricular systolic dimension (3.5 +/- 0.7 cm), left ventricular diastolic dimension (5.6 +/- 0.8 cm), end-systolic intraventricular septal thickness (1.7 +/- 0.2 cm), end-diastolic intraventricular septal thickness (1.2 +/- 0.2 cm), ejection fraction (63 +/- 10%), and fractional shortening (37 +/- 10%). Doppler echocardiography revealed a maximum aortic valve velocity of 0.9 +/- 0.5 m/s and a cardiac index of 3.7 +/- 1.1 L/minute/m2. The collected baseline data will be useful in assessing prosthetic heart valves, cardiac assist pumps, new cannulation techniques, and robotics applications in the anesthetized calf model and in developing calf models of various cardiovascular diseases.

Anesthetics, Dissociative↗