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Biomedical subjects

F Khaja

Publications and source records attributed to F Khaja.

At least 55 records · Page 3Linked to original sources
PubMed1984

Blood velocity in the right coronary artery: relation to the distribution of atherosclerotic lesions.

Vascular endothelial injury by high shear stresses and adverse effects of low shear rates on mass transfer across the arterial wall have been suggested as factors in atherogenesis. This study describes differences in blood velocity, and therefore differences of shear rate, across the lumen of the right coronary artery (RCA) of man. Selective coronary arteriograms of 30 patients without obstructive RCA disease were reviewed. Velocity was assessed qualitatively based on the rate of clearance of contrast material. There was a rapid clearing of contrast material along the outer wall of the RCA as it curved around the border of the heart. A much slower clearing occurred along the inner wall, bordering the myocardium, which persisted 2 to 6 cardiac cycles after the outer wall had cleared. This suggests that velocity, and therefore shear rate, is much lower along the inner wall of the RCA. To determine the relation of the distribution of atherosclerotic plaques in the RCA to local blood velocity, the RCA in 17 randomly selected human subjects who died of noncardiac disease were studied histologically. There was an uneven distribution of atherosclerotic plaques in the RCA with greater involvement of the inner wall. These observations demonstrate an association between the lower shear rate along the inner wall of the RCA and the site of higher concentration of atherosclerosis.

Adult↗
PubMed1984

Regional left ventricular systolic function in patients with segmental early relaxation and normal coronary arteries.

The purpose of the study was to determine whether regional differences of left ventricular systolic function exist in patients with normal coronary arteries who manifest segmental early relaxation. The presence or absence of segmental early relaxation was determined angiographically in 16 patients with normal coronary arteries who underwent diagnostic cardiac catheterization because of chest pain. Seven patients had early relaxation localized to the left ventricular anterior wall and nine patients had no evidence of segmental early relaxation. Regional function was assessed from ventriculograms obtained in the right anterior oblique projection using the area method to calculate the regional fractional area of shortening. The fractional area of shortening of the anterolateral region was greater in patients with than in those without segmental early relaxation (69 +/- 4 versus 55 +/- 11%; p less than 0.01). In addition, in patients with segmental early relaxation, this variable exceeded the fractional area of shortening of the diaphragmatic region (69 +/- 4 versus 53 +/- 9%; p less than 0.01). There was no difference in the fractional area of shortening between these two regions in patients who did not manifest segmental early relaxation. These results suggest that regional differences in systolic function are present in patients with but not in those without segmental early relaxation. Augmented regional systolic function was observed in patients with segmental early relaxation and was limited to regions that manifested early relaxation.

Adult↗
PubMed1983

Hemodynamic effects of pacing-induced tachycardia in valvular aortic stenosis.

The hemodynamic effects of tachycardia were studied in 13 patients with valvular aortic stenosis. Observations were made during sinus rhythm (average heart rate 80 beats/min) and two periods (P1 and P2) when atrial pacing increased the heart rate to 109 and 131 beats/min respectively. The cardiac index did not change, but the left ventricular stroke work index fell from 61.8 to 39.5 g X m/m2 (p less than 0.001) as the heart rate increased. The left ventricular end-diastolic pressure averaged 18 mm Hg during sinus rhythm and fell to about 11.5 mm Hg at P1 and P2 (p less than 0.001). The brachial arterial systolic pressure did not change during pacing, but the left ventricular systolic pressure fell from 208 mm Hg to 201 mm Hg during P1 (p less than 0.05) and 193 mm Hg during P2 (p less than 0.001). The mean systolic aortic valve gradient averaged 64 mm Hg during sinus rhythm and fell to 51 mm Hg during P2 (p less than 0.001), and the peak aortic valve gradient fell from 82 to 69 mm Hg during P2 (p less than 0.001). The left ventricular ejection time fraction increased from 26.9% during sinus rhythm to 31.9% during P1 (p less than 0.05) and 34.7% during P2 (p less than 0.005). Because of the prolonged left ventricular ejection time fraction and smaller stroke volume, a smaller pressure gradient developed across the stenosed valve at higher heart rates. The pacing test was of little value in assessing left ventricular function and thus is not useful during invasive investigations of valvular aortic stenosis.

Adult↗
PubMed1983

Intracoronary fibrinolytic therapy in acute myocardial infarction. Report of a prospective randomized trial.

We performed a randomized trial comparing intracoronary administration of streptokinase versus dextrose placebo within six hours after the onset of symptoms of acute myocardial infarction in 40 patients. The base-line clinical, hemodynamic, and angiographic findings were similar in the control and streptokinase-treated groups. Reestablishment of flow occurred in 12 of 20 patients treated with streptokinase and in 2 of 20 given placebo (P less than 0.05). Left ventricular function, angiographic ejection fraction, and regional wall motion, measured before and immediately after intervention, and serial radionuclide ejection fractions, measured at treatment, at 12 days, and at 5 months, were compared according to type of treatment (streptokinase vs. placebo) and outcome of therapy (reperfusion vs. no reperfusion). No statistically significant differences between groups were found. Thus, although streptokinase was more effective than placebo in achieving reperfusion, we detected no improvement of left ventricular function as a result of reestablished coronary flow.

Adult↗
PubMed1981

Functional mitral stenosis in patients with massive mitral annular calcification.

Mitral insufficiency with mitral annular calcification occurring predominantly in elderly females has been described. We studied six patients with mitral diastolic obstruction associated with mitral annular calcification without stenosis of the mitral leaflets. Three were males and three were females, aged 43-77 years. All had significant diastolic gradients across the mitral valve (mean gradient 16 mm Hg) recorded at catheterization. Two patients had aortic and three had mitral valve replacement. No patient had retraction of the mitral leaflets, diffuse thickening or fusion of the commissures at surgery or pathologic examination. Three patients had severe mitral insufficiency, one associated with voluminous prolapsing mitral leaflets and one as a result of ruptured chordae tendineae. The left ventricle was dilated in three patients, two with mitral regurgitation and one with mixed aortic valve disease. Active mitral annular motion is a normal event and is necessary for normal valvular function; severe calcification of the ring interferes with its normal diastolic relaxation and this alone may explain the holodiastolic mitral gradient found in these patients.

Acute Disease↗
PubMed1980

Computed tomography in dissection of the thoracic aorta.

Eleven patients presenting with thoracic aortic dissection were studied by computed tomography (CT). CT was usually performed with knowledge of the angiographic diagnosis. In eight cases, CT was definitive. This group included all six patients who received intravenous contrast material by bolus infusion. An algorithmic approach to patients with possible aortic dissection is suggested.

Aortic Dissection↗
PubMed1980

Porcine xenograft valves. Long-term (60-89-month) follow-up.

An analysis of 211 patients who had porcine xenograft valve replacements at Henry Ford Hospital between October 1971 and March 1974, was accomplished, with 100% follow-up. The follow-up period extended from 60-89 months after implantation. One hundred sixty-seven patients with 192 valves survived the perioperative period and were subjected to life table analysis. Hemodynamically significant porcine xenograft degeneration that required reoperation occurred in 18 patients, two of whom had infective endocarditis. Only four valves failed within 48 months of surgery. Ten of 42 (23.8%) patients with isolated aortic valve replacement and eight of 102 patients (7.8%) patients with isolated mitral valve replacement required reoperation (p < 0.01). In patients under 25 years of age, six of nine surviving patients had repeat operations. Our data indicate that porcine xenograft degeneration is related to the duration of implantation and the age of the patient at the time implantation was performed. In addition, porcine xenograft valves in the aortic position are more likely to degenerate than are those in the mitral position.

Adolescent↗
PubMed1979

Foreign body retrieval from the heart by two catheter technique.

Foreign bodies that lodge accidentally in the heart or great vessels can be retrieved successfully without thoracotomy. This report describes retrieval of a 15-centimeter-long central venous catheter lodged in the right side of the heart. Two catheters were introduced to effect retrieval, one from the arm and the other from the leg. To our knowledge this approach has not been described previously.

Aged↗
PubMed1979

Diagnostic value of visualization of the right ventricle using thallium-201 myocardial imaging.

The diagnostic significance of visualizing the right ventricle on thallium-201 myocardial perfusion scans (T-scan) at rest was studied in 53 patients. In 33 patients the right ventricle was visualized clearly on the T-scan (group A). Hemodynamic evidence of right ventricular hypertension with systolic pressure greater than or equal to 30 mmHg was present in 28 of 33 (85%) of these patients. Right ventricular volume overload with left-to-right shunt greater than 2:1 was present in three patients. Other tests were diagnostic for right ventricular enlargement and or pulmonary hypertension as follows: chest x-ray (58%), echocardiogram (36%) and electrocardiogram (15%). In an unselected group of 20 patients (group B) where resting T-scan did not show visualization of the right ventricle, the right ventricular systolic pressure was less than 30 mm Hg in all. The other noninvasive tests did not reveal presence of right ventricular hypertrophy or enlargement. T-scan appears to be a useful and sensitive test in detecting right ventricular pressure or volume overload compared with other noninvasive tests. This may be useful in detection of patients with right ventricular hypertrophy or enlargement secondary to pulmonary hypertension or other causes.

Adult↗
PubMed1979

Intracardiac sound as a diagnostic adjunct in subaortic stenosis.

The purpose of this investigation is to demonstrate the potential diagnostic value of intracardiac sound recordings in patients with subaortic stenosis. Intracardiac pressure and sound were measured in 10 patients with various types of subaortic obstructions using a catheter-tip micromanometer. Seven patients had idiopathic hypertrophic subaortic stenosis (IHSS), 2 had a subvalvular membrane, and 1 had a subvalvular tunnel. Within the left ventricular cavity, at the site of maximal systolic left ventricular pressure, either there was no systolic murmur, or the murmur was of low intensity. However, within the outflow tract of the left ventricle, distal to the site of intraventricular obstruction, a prominent systolic murmur was detected in all patients. This murmur was of higher intensity than the one measured distal to the aortic valve. In one patient, in whom no subvalvular obstruction was present, but in whom entrapment of the tip of the catheter occurred, no murmur was detected in the left ventricle even though a subvalvular pressure gradient was observed. Therefore it appears that a systolic murmur recorded with maximal intensity in the outflow tract of the left ventricle may be of substantial help in distinguishing between an artifactual intraventricular pressure gradient, and one that results from intraventricular obstruction.

Aortic Stenosis, Subvalvular↗
PubMed1978

Significance of momentary pressure changes during isovolumic relaxation.

Sudden momentary fluctuations of left ventricular, aortic, right ventricular, and pulmonary arterial pressure were noted during isovolumic relaxation of the respective ventricles. The presence of such transients raised questions related to their meaning and significance. The purpose of this report is to emphasize the nonartifactural nature of these pressure transients and to describe their origin and significance in the cardiac cycle. Pressure transients were observed in 31 of 32 patients with normal aortic valves, and in 17 patients with normal pulmonary valves in whom right-sided measurements were made. Such transients, however, were absent on the left ventricular and aortic pressure recordings of three patients with calcific aortic stenosis. These sudden changes in pressure are indicative of momentary compressions and rarefactions of the blood that occur within the ventricles and their respective arterial chambers. Whenever present, pressure transients were noted to occur coincident with the major aortic or pulmonary components of the second sound. Since intraaterial sound pressure is derived from the pressure signal by litering the low frequencies and amplifying the high frequencies, one can deduce that intraarterial sound pressure is in fact a representation of these pressure changes. The recognition of these pressure transients on an otherwise smooth ventricular, aortic, or pulmonary arterial pressure places in proper perspective their role in the production of the second heart sound.

Aorta↗
PubMed1978

Exploration of the cause of the low intensity aortic component of the second sound in nonhypotensive patients with poor ventricular performance.

This investigation was undertaken to explore the cause of the diminished second sound (S2) that may occur in normotensive patients with poorly performing ventricles. Intra-aortic sound and pressure were measured in 16 patients with angina; eight had normal ventricular performance (ejection fraction greater than or equal to 60%) and eight had poor performance (ejection fraction less than 50%). The amplitude of S2 was lower in patients with poor ventricular performance as was negative d/dt. Aortic pressure was conparable in both groups. The ampitude of S2 was linearly related to the rate of change of the pressure gradient that developed across the aortic valve during diastole (r = 0.82). The latter also correlated with negative dp/dt (r = 0.82). These observations indicate that in patients with poor ventricular performance, isovolumic relaxation may be compromised. This would cause a reduction of the rate of development of the diastolic pressure gradient, which would result in a diminished S2.

Adult↗
PubMed1978

Correlation of exercise 201thallium myocardial scan with coronary arteriograms and the maximal exercise test.

Myocardial scans obtained by injecting radioactive 201thallium during exercise were correlated with electrocardiograms obtained at rest and during exercise, with coronary arteriographic abnormalities, and with left ventriculograms in 55 patients suspected of having coronary arterial disease. Thirty-nine patients had significant coronary arterial disease, 34 of whom had abnormal myocardial scans after exercise and 21 of whom had abnormal ECGs during exercise. The myocardial scan after exercise was most frequently abnormal in the presence of significant abnormalities in the Q wave or localized left ventricular asynergy and when ST-segment depression persisted for longer than ten minutes after exercise. All patients with single-vessel disease had abnormal myocardial scans after exercise, whereas five of 29 patients with two or more abnormal vessels had normal scans. Patients with coronary arterial disease were more likely to have a normal myocardial scan after exercise when the resting ECG and left ventriculogram were normal and when exercise-induced ST-segment depression persisted for less than ten minutes. The combination of the myocardial scan after exercise and the ECG during maximal exercise had a sensitivity of 98 percent. The myocardial scan after exercise alone had a specificity of 100 percent. These observations indicate that the myocardial scan obtained by injecting 201thallium during exercise is an important diagnostic adjunct in the identification of patients with coronary arterial disease.

Adult↗
PubMed1977

The aortic closure sound in pure aortic insufficiency.

The second sound in aortic insufficiency has been described as accentuated, normal, or moderately diminished. A study of intracardiac phonocardiograms was performed to evaluate its intensity and to eliminate extracardiac factors. Pressure and intracardiac sound measurements were made in 28 patients undergoing diagnostic cardiac catheterization. Recordings were obtained above the aortic valve and within the left ventricle in 14 patients with normal aortic valves and 11 patients with aortic insufficiency uncomplicated by aortic stenosis. The amplitude of the aortic closure sound in the patients with pure aortic insufficiency, 1000 +/- 100 dynes/cm2, was significantly lower than in those patients with normal aortic valves, 3100 +/- 200 dynes/cm2 (P less than 0.001). The results indicate, therefore, that the presence of aortic insufficiency causes a diminished amplitude of the aortic closure sound. These results are supportive of the theory that the second heart sound is caused by diastolic vibrations of the closed aortic cusps. Diminished valvular vibrations and sound would occur in pure aortic insufficiency if the valve is unable to properly tense during diastole, or if the rate of development of the driving pressure is diminished.

Aortic Valve↗