Biomedical subjects
Publications and source records attributed to E D Grassman.
We report a new two-wire atherectomy technique for side branch protection. Newer, more resilient wire designs are capable of withstanding cutting forces of the Simpson atherocath device. This technique expands atherectomy application to lesions previously excluded from atherectomy as high risk lesions.
A case is described in which hugging balloons were used to perform coronary angioplasty through a single catheter. A discussion concerning selection of balloon combinations and technique is included.
To determine how well physical examination findings suggestive of mitral valve prolapse (MVP) correlate with echocardiographic evidence of MVP, we retrospectively reviewed the charts of 104 patients referred to an Air Force Cardiology Clinic for echocardiography to rule out MVP. In each case, the referring physician's specialty and his findings on cardiac physical examination were recorded. All patients had M-mode echocardiography, and half of the patients had two-dimensional echocardiography. Sensitivities, specificities, and likelihood ratios for the physical examination were calculated using echocardiography as the comparison standard. The combination of a systolic click and a systolic murmur was the physical examination finding most predictive of echocardiographic MVP, with a positive likelihood ratio of 2.43. Other combinations of physical findings yielded likelihood ratios close to 1. No differences were found based on the specialty of the examining physician. We conclude that when practicing physicians find a systolic click and murmur, MVP is likely to be present on echocardiography, though one third of the patients will have normal echocardiograms. Other combinations of physical findings are of little help in predicting echocardiographic MVP.
The constant of elastance (E-MAX) is determined by measuring continuous left ventricular pressure and volume changes during the cardiac cycle. To evaluate the effect of myocardial ischemia on contractility, E-MAX was measured from serial pressure volume loops at baseline, with atrial pacing-induced ischemia, and after the administration of intravenous nitroglycerin with repeat pacing. Ten patients undergoing cardiac catheterization for presumed coronary artery disease were evaluated by this method. The severity of the coronary artery disease was graded angiographically by using the Gensini coronary score. In 8 of the 10 patients there was a significant decrease in E-MAX during atrial pacing (P less than .05). With the administration of nitroglycerin there was an attenuation of the ischemic effect previously noted with pacing. In 3 of the 10 patients administration of nitroglycerin produced a further decrease in E-MAX with ischemia. All 3 patients had a significantly lower Gensini coronary score with a well-developed, visible coronary collateral network. The authors' results indicate that continuous pressure volume loop analysis is possible using the nuclear stethoscope. Significant ischemic changes are seen with atrial pacing, which are relieved by the administration of nitroglycerin, except in the presence of coronary collaterals.
This study evaluated effects of various anti-G inflation pressures on cardiac volumes and the relationship of these volume changes to mean arterial pressure changes. Ventricular volumes were calculated using two-dimensional echocardiography. An anti-G suit was inflated to 2, 4, and 6 psi in the standing and supine positions for 10 male subjects. In the supine position, mean arterial pressure increased from base line for all three inflation pressures (P = 0.05). The end-diastolic volume increased after 2-psi inflation (P = 0.03). Cardiac output or stroke volume did not change. After standing, mean arterial pressure (P = 0.002), end-diastolic volume (P = 0.002), and stroke volume (P = 0.05) fell after suit deflation. Peripheral vascular resistance fell in the 2- and 4-psi inflation profiles. In the standing protocol, mean arterial pressure, end-diastolic volume, stroke volume, and cardiac output rose with all three inflation pressures (P less than 0.05). After reclining, heart rate increased (P = 0.02) and mean arterial pressure fell (P less than 0.05) in the 4- and 6-psi inflation profiles after suit deflation. Increases in mean arterial pressure are caused by increases in cardiac preload and cardiac output after inflation of the anti-G suit while subjects were standing. Increased cardiac preload was not consistently seen after inflation while subjects were supine. Changes in end-diastolic volume and mean arterial pressure were dependent on the pressure used to inflate the anti-G suit.
The hemodynamic effects of graded-dose infusions of amrinone (maximal dose 30 micrograms/kg/min) (10 patients) and isoproterenol (maximum dose 4 micrograms/min) (11 patients) were assessed in patients with a range of left ventricular (LV) function. LV ejection fraction ranged from 0.13 to 0.77 (mean +/- standard deviation 0.47 +/- 0.23) among the patients who received amrinone and from 0.24 to 0.77 (mean 0.52 +/- 0.18) among those who received isoproterenol. Peak-dose amrinone produced a reduction in LV filling pressure (from 15 +/- 10 to 10 +/- 7 mm Hg, p less than 0.001), but no significant change in heart rate, cardiac output, mean aortic pressure, total systemic vascular resistance (TSVR) or LV dP/dt max. In contrast, peak-dose isoproterenol produced a similar reduction in LV filling pressure (from 17 +/- 12 to 13 +/- 13 mm Hg, p less than 0.05), but also caused increases in heart rate, cardiac output and LV dP/dt max and decreases in mean aortic pressure and TSVR (p less than 0.001). The absolute change in cardiac output and stroke volume correlated closely with the change in TSVR in response to amrinone (r = -0.90, p less than 0.001 and r = -0.84, p = 0.002, respectively), but not in response to isoproterenol. Although isoproterenol produced a marked increase in cardiac output and LV dP/dt max (not explained by heart rate changes alone) in all patients, amrinone produced an increase in cardiac output only in those with markedly elevated LV filling pressures (who had a reduction in TSVR), and an increase in LV dP/dt in a minority.
The magnitude (Zrs) and phase angle (thetars) of the total respiratory impedance (Zrs), from 3 to 45 Hz, were rapidly obtained by a modification of the forced oscillation method, in which a random noise pressure wave is imposed on the respiratory system at the mouth and compared to the induced random flow using Fourier and spectral analysis. No significant amplitude or phase errors were introduced by the instrumentation. 10 normals, 5 smokers, and 5 patients with chronic obstructive lung disease (COPD) were studied. Measurements of Zrs were corrected for the parallel shunt impedance of the mouth, which was independently measured during a Valsalva maneuver, and from which the mechanical properties of the mouth were derived. There were small differences in Zrs between normals and smokers but both behaved approximately like a second-order system with thetars = 0 degree in the range of 5--9 Hz, and thetars in the range of +40 degrees at 20 Hz and +60 degrees at 40 Hz. In COPD, thetars remained more negative (compared to normals and smokers) at all frequencies and crossed 0 between 15 and 29 Hz. Changes in Zrs, similar in those in COPD, were also observed at low lung volumes in normals. These changes, the effects of a bronchodilator in COPD, and deviations of Zrs from second-order behavior in normals, can best be explained by a two-compartment parallel model, in which time-constant discrepancies between the lung parenchyma and compliant airway keep compliant greater than inertial reactance, resulting in a more negative phase angle as frequency is increased.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
OBJECTIVE: To determine whether echocardiography affects the decisions to use beta blockers or to recommend bacterial endocarditis prophylaxis in patients suspected of having mitral valve prolapse (MVP). DESIGN: Retrospective review of echocardiograms and clinical records. SETTING: Military tertiary care hospital. PATIENTS: 127 patients with clinically suspected MVP (105) or incidentally discovered MVP (22). MAIN RESULTS: Beta blockers were used more often in patients with suspected MVP and positive echocardiograms (45%) than in patients with normal echocardiograms (13%, p less than 0.001). Bacterial endocarditis prophylaxis was recommended more often in patients with suspected MVP and positive echocardiograms (65%) than in patients with normal echocardiograms (11%, p less than 0.001). Presence or absence of a murmur did not influence the decision to recommend bacterial endocarditis prophylaxis. Patients in whom MVP was incidentally discovered were unlikely to receive either beta blockers or the recommendation for bacterial endocarditis prophylaxis. CONCLUSIONS: The results of echocardiography affect the decisions to use beta blockers or to recommend bacterial endocarditis prophylaxis in patients with suspected MVP.