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Biomedical subjects

R Rokey

Publications and source records attributed to R Rokey.

52 records · Page 3Linked to original sources
PubMed1988

Balloon dilation of unoperated coarctation of the aorta: short- and intermediate-term results.

Balloon dilation is effective in the immediate relief of obstruction due to unoperated coarctation of the aorta. However, the long-term benefits and complications of this procedure have not been established. Thirty-three patients underwent balloon dilation of unoperated coarctation using a percutaneous technique from November 1983 to December 1985. High quality biplane angiography was performed before and after dilation. Follow-up was obtained in 20 patients from 6 to 31 months following dilation. Angiography was performed at follow-up in 10, nuclear magnetic resonance (NMR) imaging in 10 and both NMR imaging and angiography in 3. Balloon dilation was successful in 31 of the 33 patients with a decrease in average systolic pressure gradient from 46 to 8 mm Hg. There was no significant change in gradient on follow-up physical examination and at recatheterization in 10 patients. In addition, there was no evidence of restenosis on follow-up angiography and NMR imaging. In two patients, a small aneurysm formed at the site of balloon dilation. Balloon dilation of unoperated coarctation is effective, providing lasting relief of coarctation gradient and no evidence of restenosis. However, because of the uncertain natural history of aneurysms after dilation, this procedure should be considered investigational until further follow-up on patients with and without an aneurysm is available.

Angiography↗
PubMed1987

Quantification of atrial contribution to left ventricular filling by pulsed Doppler echocardiography and the effect of age in normal and diseased hearts.

Atrial filling fraction, or the fraction of stroke volume resulting from atrial contraction, was measured by Doppler echocardiography from the time-velocity integral of mitral anulus inflow with a method that allows separation of conduit or passive flow from flow resulting from the atrial contraction. The method was validated in 17 patients with externally programmable ventricular demand pacemakers by showing that the time-velocity integral of passive flow (excluding the A wave) during sinus or sequential atrioventricular pacing was almost identical to the time-velocity integral during ventricular pacing. Atrial filling fractions were then measured in 41 normal subjects, aged 20 to 80 years; 28 patients with echocardiographic evidence of concentric left ventricular hypertrophy; 24 with dilated cardiomyopathy (13 of whom had an ischemic origin); and 19 with acute myocardial infarction. Atrial filling fraction increased significantly with age in normal subjects (r = 0.77; p less than 0.001) and ranged from 12% in a 20-year-old man to 46% in a normal 80-year-old woman. In the hypertrophy group, atrial filling fraction had a weak relation with age (r = 0.47; p = 0.006), and the values were significantly higher than in normal subjects. In patients with cardiomyopathy or infarction, atrial filling fraction varied over a wide range and showed no relation to age. Thus, atrial filling fraction as determined by Doppler echocardiography is significantly altered by both age and left ventricular disease. Age-corrected nomograms are essential when assessing atrial filling fraction in individual patients.

Adult↗
PubMed1987

Assessment of left ventricular diastolic filling by two-dimensional echocardiography.

Although two-dimensional echocardiography has provided accurate measurements of left ventricular ejection fraction, the technique has been limited in the evaluation of diastolic function. First half-filling fraction, representing the difference between mid-diastolic and end-systolic volumes divided by stroke volume, is a recently introduced index of diastolic function. We developed a method for determining half-filling fraction by two-dimensional echocardiography with the use of the average of left ventricular internal diameters measured at the base, middle, and apical third of the ventricular cavity in multiple longitudinal planes. In 27 patients with a wide range of ventricular function, we compared angiographic measurements of half-filling fraction to results obtained by two-dimensional echocardiography. Half-filling fraction measured angiographically averaged (mean +/- SD) 0.58 +/- 0.15 (range 0.26 to 0.77) and measured by two-dimensional echocardiography averaged 0.58 +/- 0.15 (range 0.35 to 0.90). A significant correlation was found between angiographic and echocardiographic half-filling fractions (r = 0.84, SEE = 0.08). Results were similar in the presence or absence of segmental wall motion abnormalities. All seven patients with half-filling fractions below 0.50 by echocardiography had depressed half-filling fractions by angiography; three of these patients had ejection fractions of greater than or equal to 0.55. Thus half-filling fraction can be derived with two-dimensional echocardiography providing a noninvasive assessment of diastolic function.

Adult↗
PubMed1987

Creatine kinase isoform analysis in the detection and assessment of thrombolysis in man.

Recent demonstrations of the efficacy of intravenous thrombolytic therapy in acute myocardial infarction have emphasized the need for a noninvasive index of successful reperfusion. The tissue form of MM creatine kinase (MM3) is known to undergo posttranslational conversion to modified forms MM2 and MM1 after release into the plasma following acute infarction. Since this conversion is rapid, sustained elevation of plasma MM3 may be a marker of the prolonged creatine kinase release characteristic of nonreperfused infarction. Therefore, we investigated the rate of decline of plasma MM3 in a consecutive series of patients undergoing thrombolytic therapy of acute myocardial infarction, all of whom underwent acute angiography to assess treatment success, as well as in 30 conventionally treated patients. Among 55 patients with angiographically documented successful reperfusion (group IA), the rate of decline of MM3 was 4.18 +/- 1.25%/hr (mean +/- SD); in contrast, the rate of decline was 2.37 +/- 1.11%/hr in 39 patients with angiographically documented unsuccessful reperfusion (group IB) and 1.77 +/- 1.46%/hr among the 30 patients receiving conventional treatment (group II) (p less than .001 for groups IB and II vs group IA). A cutoff value of 3.1%/hr minimized the overlap between the groups; 48/55 (87%) patients with successful reperfusion had a rate of decline of MM3 of 3.1%/hr or more, while 29 of 39 (74%) patients in whom thrombolysis was unsuccessful and 27 of 30 (90%) patients receiving conventional treatment had a rate of decline less than 3.1%/hr (p less than .001 for groups IB and II vs group IA).(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗
PubMed1987

Nuclear magnetic resonance imaging of the cardiovascular system.

Nuclear magnetic resonance (NMR) imaging provides a noninvasive method of detecting and characterizing several clinically important cardiac diseases. These include hypertrophic cardiomyopathy, several congenital disorders, especially those with abnormalities of the surrounding great vessels and those with surgical shunts in place, intra and extra cardiac masses and constrictive pericarditis. NMR imaging is becoming useful in the visualization of aortic disease, particular for the serial management of coarctation, and for the diagnosis of thoracic and abdominal aneurysms and dissections. Other peripheral vascular lesions such as portal shunts and arterial-venous malformations are detected. With further experience and improved technology, NMR imaging will become a valuable tool for the detection and characterization of recent infarction, monitoring of cardiac transplantation patients for the presence of rejection, detection of myocardial iron overload and the visualization of peripheral vascular disease. For NMR imaging to become firmly entrenched as a cardiovascular imaging tool, however, it will be necessary to carefully document its advantage over already well established and less expensive methods, such as radionuclide imaging techniques and 2-D echocardiography. Moreover, NMR imaging will need to be compared to developing technology like cine computerized X-ray tomography before the best noninvasive imaging technique is finally established for a particular cardiovascular disease.

Aortic Diseases↗
PubMed1986

Determination of regurgitant fraction in isolated mitral or aortic regurgitation by pulsed Doppler two-dimensional echocardiography.

Measurements of mitral and aortic valve flows were obtained with two-dimensional Doppler echocardiography in 25 patients with isolated mitral (n = 19) or aortic (n = 6) regurgitation and regurgitant fraction was calculated as the difference between the two flows divided by the flow through the regurgitant valve. Results were compared with measurements of regurgitant fraction determined by combined left ventricular angiography and thermodilution. Regurgitant fraction averaged 56 +/- 18% (range 19 to 79) by Doppler echocardiography and 48 +/- 17% (range 13 to 72) by angiography. A significant correlation was observed between the two methods (r = 0.91; SEE = 7%). In contrast, no significant correlation was found between regurgitant fraction measured by either method and the angiographic 1+ to 4+ qualitative classification of regurgitation. Doppler echocardiography appears to be an accurate method for the non-invasive quantification of severity of regurgitation in isolated left-sided valve lesions.

Adolescent↗
PubMed1986

Myocardial infarct size quantification by MR imaging early after coronary artery occlusion in dogs.

The feasibility of using magnetic resonance (MR) imaging to estimate myocardial infarct size was explored in an in vitro model using only the inherent differences in contrast between infarcted and noninfarcted myocardium. Eight dogs underwent coronary occlusion; their hearts were removed 6 hours later. Estimates of T2 for normal and infarcted myocardium were derived from MR images. Infarct size was quantified anatomically using triphenyltetrazolium-chloride (TTC) staining and compared with MR estimates. The T2 values derived from the images clearly discriminated between infarcted (126 +/- 22 msec) and normal myocardium (88 +/- 10 msec, P less than .05), providing images with good contrast between normal and infarcted myocardium. Comparable differences in T2 values were also noted from spectrometric determinations. Estimates of infarct size by MR imaging compared well with TTC estimates (r = 0.98) over a wide range of infarct sizes from 3% to 29% of the left ventricular mass. These results suggest the potential for in vivo quantification of infarct size based on the inherent contrast difference between infarcted and normal myocardium.

Animals↗
PubMed1986

Magnetic resonance imaging in moyamoya disease.

Magnetic resonance imaging of the brain in a patient with moyamoya disease demonstrated multiple scattered white matter lesions, but was not sufficiently specific to confirm the diagnosis without other techniques.

Arterial Occlusive Diseases↗
PubMed1986

Silent myocardial infarction and diabetic cardiovascular autonomic neuropathy.

Seventy-three consecutive diabetic adults with symptomatic peripheral neuropathy were evaluated for the presence of cardiovascular autonomic neuropathy and electrocardiographic evidence of myocardial infarction (MI). Twenty-five (34.2%) patients demonstrated cardiovascular autonomic neuropathy, and ten (13.7%) patients had electrocardiographic evidence of MI. Of the ten MI identified, seven were asymptomatic (silent) by history. The incidence of silent MI was significantly higher (P less than .04) in patients with cardiovascular autonomic neuropathy. It is postulated that sudden death in diabetic patients with cardiovascular autonomic neuropathy may be due to silent MI.

Adult↗
PubMed1985

Mitral-septal angle: a new two-dimensional echocardiographic index of left ventricular performance.

The diagnostic value of a new two-dimensional echocardiographic measurement, the mitral septal angle, was evaluated as an index of left ventricular (LV) function in 122 patients. Their mean age was 56.5 years and the majority (80%) suffered from coronary artery disease, 46 with an acute myocardial infarction. Mitral septal angle was easily and reproducibly measured. An ejection fraction (EF) of greater than or equal to 50% and an angle less than or equal to 30 degrees were used as normal cut-off values. A strong negative correlation was found between the angle and radionuclide EF (-0.821) and angiographic EF (-0.82) in patients without acute myocardial infarction. For patients with acute myocardial infarction, the correlation was -0.722. For the entire group, the correlation coefficient was -0.742. In patients without acute infarction, the sensitivity, specificity, and predictive accuracy of the mitral septal angle were 92%, 86%, and 89%, respectively. In acute infarction, sensitivity dropped to 70% without change in specificity (89%). We conclude that mitral septal angle is a simple index of LV function which relates well to EF, particularly in patients with chronic heart disease.

Adult↗
PubMed1985

Determination of parameters of left ventricular diastolic filling with pulsed Doppler echocardiography: comparison with cineangiography.

To determine the relationship between Doppler-derived flow velocity through the mitral anulus and angiographic parameters of left ventricular filling, 30 patients were studied by two-dimensional echocardiography combined with pulsed Doppler echocardiography followed within 1 hr by left ventricular angiography. The average heart rate for each test was 69 beats/min. Doppler-derived parameters included: early peak diastolic velocity (E) and peak atrial velocity, peak filling rate computed as E X cross-sectional area of the mitral anulus derived from the annular diameter, normalized peak filling rate computed as peak filling rate divided by the left ventricular end-diastolic volume determined by two-dimensional echocardiography, and half filling fraction derived from the time-velocity integral of the Doppler-determined velocity curve. Frame-by-frame left ventricular volumes were obtained throughout diastole from single-plane cineangiograms. A volume-time curve with its derivative was generated by computer processing from which peak filling rate, normalized peak filling rate, and half filling fraction were measured. Morphologically, the Doppler-derived velocity profile resembled the derivative of the angiographic volume curve. In patients with reduced angiographic peak filling rates, early peak diastolic velocity was often decreased less than 45 cm/sec with a relative increase in peak atrial velocity resulting in an early peak diastolic velocity to peak atrial velocity ratio less than 1.0. There were no significant differences in mean values for peak filling rate, normalized peak filling rate, and half filling fraction by Doppler echocardiography vs angiography (296 vs 283 ml/sec, 1.9 vs 2.0 sec-1 and 0.55 vs 0.55, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Coronary artery disease in patients with cerebrovascular disease: a prospective study.

Coronary artery disease is the cause of death in most patients who have transient ischemic attacks or stroke. Evaluation for this condition is not routinely performed in such patients, and no prospective studies have been reported. We prospectively examined 50 consecutive patients with transient ischemic attacks or mild stroke to determine the prevalence and importance of coronary artery disease. All patients were examined by a cardiologist and underwent both exercise thallium-201 scintigraphy and exercise radionuclide ventriculography. Sixteen patients were suspected to have coronary artery disease on the basis of clinical evaluation. In 15 of these the was confirmed by the nuclear scans. The remaining 34 patients had no clinical evidence of heart disease, yet 14 had abnormal cardiac scans. Twenty of 22 patients with abnormal scans who underwent cardiac catheterization had significant coronary artery disease or a cardiomyopathy. The discovery of heart disease altered clinical management in 13 patients. Overall, 29 of 50 patients had significant coronary artery disease, compared with a 7% prevalence of the condition in other patients of similar age at the same institution.

Cerebral Angiography↗
PubMed1984

Isolated left posterior fascicular block associated with acquired ventricular septal defect.

Isolated left posterior fascicular block in the absence of associated right bundle-branch block is a rare electrocardiographic finding. In view of its anatomy and the fact that it receives a dual blood supply, the posterior fascicle of the left bundle branch appears to be less vulnerable than the anterior fascicle or the right bundle. Mechanical disruption of the posterior fascicle can produce isolated left posterior fascicular block. This has been demonstrated in animal models. However, such occurrence has not been noted in humans. We present two cases of inferior wall myocardial infarction, complicated by rupture of the inferior septum, resulting in isolated left posterior fascicular block. The development of isolated left posterior fascicular block complicating myocardial infarction may, therefore, serve to alert to the possible underlying septal rupture.

Bundle-Branch Block↗
PubMedDate not supplied

An electrocardiograph-respiration gating device for MR studies.

A versatile gating device for magnetic resonance (MR) spectroscopy and imaging is presented. The device uses electrocardiograph (ECG) and respiration signals as input, applies appropriate signal conditioning, and generates control signals for ECG, respiration, or combined gating studies. In the combined ECG and respiration mode, in conjunction with a proper MR pulse program, one can acquire MR data gated by the ECG signal within a selected window of the respiration cycle, while maintaining a steady level of magnetization saturation during the remainder of the respiration cycle, by gating the radio-frequency excitation with the ECG while inhibiting data acquisition.

Animals↗