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Biomedical subjects

J G Kegel

Publications and source records attributed to J G Kegel.

7 recordsLinked to original sources
PubMed1998

Correlation between hemodynamic changes and tomographic sestamibi imaging during dipyridamole-induced coronary hyperemia.

OBJECTIVES: The purposes of this study were to examine the effects of dipyridamole infusion on hemodynamic variables and to compare these changes with myocardial perfusion. BACKGROUND: Dipyridamole stress testing with myocardial perfusion imaging is widely used in the assessment of patients with known or suspected coronary artery disease (CAD). Few studies, however, have correlated the hemodynamic effects of dipyridamole using invasive monitoring with perfusion patterns in patients with chest pain syndromes. METHODS: Hemodynamic measurements were made in the cardiac catheterization laboratory with a Swan-Ganz thermodilution catheter before, during and after infusion of dipyridamole (142 microg/kg body weight per min for 4 min). Technetium-99m sestamibi was injected 3 min after the completion of the infusion. RESULTS: There were 20 patients with and 6 without CAD, as demonstrated by angiography. Compared with baseline values, dipyridamole resulted in an increase in pulmonary capillary wedge pressure (54 +/- 78% vs. 32 +/- 26%, p = NS), cardiac index (36 +/- 21% vs. 40 +/- 18%, p = NS) and stroke volume index (16 +/- 18% vs. 40 +/- 18%, p = NS) and a decrease in systemic vascular resistance (22 +/- 13% vs. 24 +/- 11%, p = NS), aortic pressure (2 +/- 9% vs. 0 +/- 6%, p = NS) and pulmonary vascular resistance (19 +/- 25% vs. 11 +/- 32%, p = NS) in patients with and without CAD. The peak effect of dipyridamole on heart rate, systemic vascular resistance and pulmonary capillary wedge pressure was evident at 3 min after infusion in 70% of patients. Aminophylline, given to 20 patients, improved hemodynamic variables within 2 min. The single-photon emission computed tomographic sestamibi images were normal in the 6 patients without and abnormal in the 18 patients with CAD. CONCLUSIONS: Dipyridamole-induced coronary hyperemia produces mild hemodynamic changes in patients with and without CAD; these changes are at or near peak effect at 3 min after infusion and are rapidly reversed by aminophylline.

Adult↗
PubMed1995

Relation between diastolic left ventricular function and myocardial blood volume during adenosine-induced coronary hyperemia.

Adenosine infusion is accompanied by increases in coronary blood flow and myocardial blood volume. Myocardial blood volume may produce changes in diastolic left ventricular (LV) performance by increasing myocardial turgor. Diastolic dysfunction may also be the result of myocardial ischemia. The relation between changes in LV mass and diastolic function has not been previously investigated. This study examined the relation between changes in LV mass during adenosine-induced coronary hyperemia and LV diastolic function. Serial two-dimensional and Doppler echocardiographic measurements were made before, during, and after adenosine infusion (140 micrograms/min for 6 min) in 21 patients with (group 1) and 10 patients without (group 2) coronary artery disease (CAD). The LV mass and transmitral diastolic filling indexes were determined from digitized images from apical four-chamber view. Adenosine infusion produced a greater increase in LV mass in group 2 than in group 1 (29% +/- 11% vs 9% +/- 6%, p < 0.0002). The ratio of transmitral early (E) to atrial (A) filling velocity (E/A) increased 10% +/- 16% in group 2 and decreased 8% +/- 20% in group 1 (p < 0.02), and the velocity time integral of early filling increased 11% +/- 52% in group 2 and decreased 20% +/- 31% in group 1 (p < 0.04). There was a correlation between the change in E/A ratio and the LV mass (r = 0.53, p < 0.003). Thus adenosine infusion caused a greater increase in LV mass in normal subjects than in patients with CAD. There were also changes in Doppler-derived indexes of diastolic LV function.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1993

Simplified method for calculating aortic valve resistance: correlation with valve area and standard formula.

Aortic valve resistance (AVR) is a useful index to assess the severity of aortic stenosis. This study compared the standard method to calculate AVR with a simplified method based on the conventional approach for measuring vascular resistance: AVR = (peak-to-peak transaortic pressure gradient/(cardiac output*2.5))*80, where 80 is a conversion factor and 2.5 assumes that the systolic ejection period comprises 40% of the R-R cycle. We compared the standard AVR, the simplified AVR, and the Gorlin-derived value area in 118 patients with pure or dominant aortic stenosis. There was a strong linear correlation between the standard and simplified AVR (r = 0.96, p < .0001). There was a curvilinear relation between the aortic valve area and AVR (r = 0.92, p < .001). In 48 patients with aortic valve area > or = 0.7 cm2, the AVR was < 300 dynes-sec-cm-5 in 45 patients (94%) by the standard method and in 42 patients (88%) by the simplified method (p = NS). In conclusion, our method for measuring AVR is accurate and simpler than the standard method.

Aged↗
PubMed1993

Simultaneous assessment of left ventricular perfusion and function with technetium-99m sestamibi after coronary artery bypass grafting.

This study examined the left ventricular perfusion and EF by using simultaneous SPECT and first-pass radionuclide angiography with technetium 99m sestamibi in 95 patients after uncomplicated coronary artery bypass grafting. The patients were divided into those with normal EF and no previous myocardial infarction before surgery (group 1, n = 57), and those with abnormal EF or infarction (group 2, n = 38). The SPECT images were normal in 37 patients in group 1 and in 6 patients in group 2 (p < 0.0001). The patients with normal SPECT images had a higher EF after surgery than those with abnormal images (65% +/- 10% vs 50% +/- 14%, p < 0.0001) and was higher in group 1 than in group 2 (64% +/- 8% vs 46% +/- 16%, p < 0.0001). There was a significant correlation between the EF and the extent of perfusion abnormality (r = -0.44, p < 0.0001). The patients with normal SPECT images could not be separated from those with abnormal images based on peak CK, CK-MB, and the electrocardiographic changes. Of the 69 patients with postoperative EF > or = 50%, the perfusion pattern was normal in 41 and abnormal in 28; of the 26 patients with EF < 50%, 24 had abnormal SPECT (p < 0.003). There was no significant change in mean EF after surgery (55% +/- 14% before vs 56% +/- 15% after). Thus simultaneous assessment of left ventricular perfusion and function after coronary artery bypass grafting showed that an abnormal perfusion pattern may exist despite a normal EF. These patients could not be predicted by enzymes or electrocardiographic changes.

Aged↗
PubMed1992

Mechanism of exercise-induced hypotension in coronary artery disease.

Hypotension during exercise testing has been considered a marker of extensive coronary artery disease (CAD) and poor prognosis. The mechanism of hypotension was examined in 25 CAD patients who developed hypotension during treadmill exercise testing (mean decrease in systolic blood pressure [BP] 33 +/- 13 mm Hg) (group 1) and was compared with the results of 25 CAD patients who had a normal systolic BP response to exercise (mean increase 53 +/- 15 mm Hg) (group 2). The 2 groups were comparable in age, sex, extent of CAD, previous myocardial infarction, left ventricular ejection fraction, history of hypertension and cardiac medications. Exercise heart rate (121 +/- 23 vs 133 +/- 25 beats/min; p = not significant [NS]) and duration (6 +/- 2 vs 7 +/- 3 minutes; p = NS) were comparable. ST-segment depression occurred in 44% of patients in group 1 and in 52% in group 2 (p = NS), and angina during exercise occurred in 60% of both groups. Single-photon emission computed tomographic thallium images were abnormal in 24 patients (96%) in group 1 and in 20 patients (80%) in group 2 (p = NS). Percent thallium abnormality was 19 +/- 12% in group 1, and 18 +/- 14% in group 2 (p = NS), and the severity of thallium abnormality was 710 +/- 510 in group 1, and 510 +/- 500 in group 2 (p = NS). Ischemia involving the inferior/posterior segments was seen in 68% of patients in group 1 and in 60% in group 2 (p = NS). Increased lung thallium uptake was seen in 48% of both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗