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Biomedical subjects

W Grossman

Publications and source records attributed to W Grossman.

At least 199 records · Page 11Linked to original sources
PubMed1978

Severe stenosis occurring in antibiotic sterilised homograft valves.

This paper describes 3 patients who developed late severe stenosis in fresh antibiotics sterilised homograft valves. Two were in the aortic position and one in the mitral. All 3 patients underwent successful reoperation. This complication has not been previously reported in valves prepared by this method.

Adult↗
PubMed1977

Effect of angina on the left ventricular diastolic pressure-volume relationship.

The increased left ventricular end-diastolic pressure associated with myocardial ischemia was studied in 19 patients at cardiac catheterization. Single plane left ventriculograms were performed using high fedelity micromanometer tipped catheters before and immediately following rapid atrial pacing. Left ventricular diastolic properties were evaluated by constructing diastolic pressure-volume curves from the simultaneous pressure and volume data. In seven control patients, there was no significant change in left ventricular hemodynamics or the diastolic pressure-volume curve after atrial pacing. Twelve patients with significant coronary artery disease developed angina during pacing and had an increased left ventricular end-diastolic pressure (18 +/- 2 mm Hg, control, vs 30 +/- 2 mm Hg, angina, P less than .01) in the immediate post-pacing period. In these patients, the post-pacing ejection fraction was modestly decreased (0.63 +/- 0.03, control, vs 0.57 +/- 0.03, angina P less than 0.01), and left ventricular volumes at end systole (59 +/- 8 cc, control, vs 74 +/- 9 cc, angina, P less than 0.0125) were increased. The post-pacing diastolic pressure-volume curves in all 12 patients were shifted upward as compared with control so that for any given diastolic volume, pressure was higher during angina. The data indicate that the increased left ventricular diastolic pressure during myocardial ischemia is the result of both impaired left ventricular systolic performance and altered left ventricular diastolic properties.

Adult↗
PubMed1977

Contractile state of the left ventricle in man as evaluated from end-systolic pressure-volume relations.

End-systolic pressure (PES), volume (VES), wall tension (TES) and circumference (CES) of the human left ventricle were studied at cardiac catheterization in 24 subjects with varying degrees of left ventricular dysfunction. Acute alterations in systolic load consistently resulted in changes in VES and CES, with a smaller volume and circumference characterizing the lower systolic load in each subject. End systolic pressure-volume lines were constructed by plotting PES against VES at the higher and lower systolic load in each subject. The slope of the resultant lines was considerably steeper for normal than for poorly contractile left ventricles. Vo, the volume axis intercept of the line (i.e., the theoretical VES at PES = O) was significantly smaller for normal than for poorly contractile ventricles. Similar findings were noted for Co, the theoretic end-systolic circumference at zero end-systolic ventricular wall tension. Post-extrasystolic potentiation resulted in decreased VES and CES with no change in PES and only a slight fall in TES. In conclusion, end-systolic pressure-volume and tension-circumference relations reflect the contractile state of left ventricular myocardium. Quantitation of these relationships may provide a useful new approach to the assessment of myocardial function in man.

Blood Pressure↗
PubMed1977

Effects of sodium nitroprusside on left ventricular diastolic pressure-volume relations.

The effect of sodium nitroprusside on the relationship between left ventricular pressure and volume during diastole was studied in 11 patients with congestive heart failure. Nitroprusside was infused to lower mean arterial pressure approximately 20-30 mm Hg. High fidelity left ventricular pressures were recorded in all patients simultaneously with left ventricular cineangiography (biplane in eight and single plane in three patients), allowing precise measurement of pressure and volume throughout the cardiac cycle. Left ventricular diastolic pressure-volume curves were constructed in each patient from data obtained before and during nitroprusside infusion. In 9 of 11 patients there was a substantial downward displacement of the diastolic pressure-volume curve during nitroprusside infusion, with left ventricular pressure being lower for any given volume with nitroprusside. Serial left ventricular cineangiograms performed 15 min apart in six additional subjects who did not receive sodium nitroprusside showed no shift in the diastolic pressure-volume relation, indicating that the shift seen with nitroprusside was not due to the angiographic procedure itself. A possible explanation for the altered diastolic pressure-volume relationships with nitroprusside might be a direct relaxant effect of nitroprusside on ventricular muscle, similar to its known relaxant effect on vascular smooth muscle. Alternatively, nitroprusside may affect the diastolic pressure-volume curve by affecting viscous properties or by altering one or more of the extrinsic constraints acting upon the left ventricle.

Aorta↗
PubMed1976

Reflex increase in coronary vascular resistance in patients with ischemic heart disease.

To assess possible coronary vasoconstriction in patients with ischemic heart disease, we measured coronary vascular resistance in 12 patients with normal hearts and 12 with coronary disease before and during the initial 50 seconds of cold pressor test, a stimulus known to produce systemic vasoconstriction. Control coronary vascular resistance was similar in the two groups, and although it did not change in patients with normal vessels, it rose by 27 per cent (P less than 0.005) in the group with coronary disease during the cold pressor test. In three of 12 patients with coronary disease coronary flow actually declined despite an increase in arterial pressure; in four, angina was precipitated. Phentolamine abolished increases in arterial pressure and coronary vascular resistance during the test in three patients with coronary disease. Adrenergically mediated coronary vascular tone may be an important determinant of coronary blood flow and may contribute to ischemia in patients with coronary disease.

Adrenergic alpha-Antagonists↗
PubMed1976

The effect of morphine on the activity evoked in ventrolateral tract axons of the cat spinal cord.

The effect of morphine on the activity in ventrolateral tract axons was studied in intercollicularly decerebrate cats with and without spinal section. Activity was elicited by electrical stimulation of Adelta- and C-fibres in the sural nerves. In spinal animals, morphine injected intravenously in a dose as low as 0.5 mg/kg reduced the post-stimulus discharge of impulses recorded in ventrolateral tract axons below the site of transection. The depression was not only abolished but reversed by levallorphan and naloxone. Pretreatment with reserpine did not diminish the effect of morphine. The effect of morphine was considerably weaker in decerebrate cats. Reversible block of the spinal cord produced by cold revealed that morphine reduced inhibition from the brain stem controlling the impulse transmission to ventrolateral tract axons. It is concluded that a spinal effect contributes to the analgesic action of morphine.

Afferent Pathways↗
PubMed1976

Combined hemodynamic-ultrasonic method for studying left ventricular wall stress: comparison with angiography.

Calculation of left ventricular wall stress in man has traditionally required angiographic and left ventricular pressure measurement, making study of interventions difficult. We have developed a combined hemodynamic-ultrasonic technique for measuring left ventricular meridional wass stress (sigma m) throughout the cardiac cycle. Simultaneous measurements of left ventricular pressure, ultrasonically determined wall thickness (h[echo]), and minor axis (D[echol]) were made during cardiac catheterization in nine subjects, three with chronic left ventricular pressure overload, four with left ventricular volume overload and two with normal left ventricular function. Within 30 minutes, left ventricular cineangiography was performed in each subject and angiographic wall thickness (h[angio]) and minor axis (D[angio]) were measured. Comparison of values for each subject throughout the cardiac cycle (average 18 data points/cycle) yielded close correlation: For D(echo) versus D(angio), r values ranged from 0.82 to 0.98 whereas for h(echo) versus h(angio), r values ranged from 0.56 to 0.98 for the nine subjects. Meridional wall stress was calculated after the method of Sandler and Dodge as PRi2/h(2Ri + h), where Ri equals the inner wall radius, calculated as D/2 for both ultrasonic and angiographic methods. Agreement between ultrasonic and angiographic methods was excellent in each subject, with close superimposition of the stress-time plots constructed by the different techniques. In summary, a new method for measurement of left ventricular wall stress has been developed and validated by comparison with an angiographic reference standard. This method has potential advantages, including the ability to study meridional wall stress continuously and to assess its response to serial interventions.

Cineangiography↗
PubMed1976

An echocardiographic study of the interventricular septum in constrictive pericarditis.

Ten patients with constrictive pericarditis were studied echocardiographically with specific reference to inter-ventricular septal dynamics. Abnormal movement of the interventricular septum was present in 8 patients and consisted of flattening in systole and unusual posterior motion in diastole. The aetiology of this type of movement is at present unknown but may be related to restriction of normal cardiac rotational dynamics. The interventricular septum also showed diminished degree of thickening (mean 21-2%). The amplitude of excursion was generally at the upper limit of or greater than normal. Left ventricular posterior wall amplitude of excursion was normal. Flattening of left ventricular posterior wall diastolic movement was seen in 4 patients. Right ventricular end-diastolic dimension was slightly increased (1-2 to 1-7 cm/m2) in 5 of 8 patients with abnormal septal motion, but no haemodynamic evidence of diastolic volume overload was found. Posterior pericardial thickening was noted echocardiographically when posterior calcification was present. We conclude that the most common though non-specific feature of the echocardiogram in patients with constrictive pericarditis is abnormal septal motion. Flattening of left ventricular posterior wall diastolic movement, posterior pericardial thickening, and epicardial-pericardial separation may also occur.

Adult↗
PubMed1976

Diagnosis of prosthetic mitral valve malfunction with combined echo-phonocardiography.

Fifty-three patients were studied with combined echo-phonocardiography or phonocardiography alone following prosthetic valve replacement. In sixteen of these patients, clinical deterioration developed, and all subsequently underwent cardiac catheterization and/or surgery. Two patients came to autopsy. Included in this group of sixteen patients were five with obstructed prosthesis, six with paravalvular regurgitation, and five with left ventricular dysfunction. Measurements were made of the time interval from the aortic valve closure sound to the peak opening of the mitral prosthesis determined echocardiographically or to the mitral prosthetic opening click (A2-MVO). Echocardiographic studies of left ventricular wall motion were also performed. The A2-MVO interval was significantly shortened (P less than 0.01) with prosthetic valve obstruction (.05 +/- .02 sec) and paravalvular regurgitation (.05 +/- .01 sec) compared with normally functioning prostheses (Starr-Edwards ball valves .10 +/- .02 sec, Lillehei-Kaster tilting disc prostheses .09 +/- .01 sec). Shortening of this interval was not specific for these conditions because it was sometimes shortened with left ventricular dysfunction. Echocardiographic studies of left ventricular wall motion were helpful in distinguishing among prosthetic valve obstruction, paravalvular regurgitation and left ventricular dysfunction. The combined echo-phonocardiographic technique was especially helpful in detecting malfunction of tilting disc prostheses, because the technique enables measurement of the A2-MVO interval in the absence of an audible opening click.

Adult↗
PubMed1976

Effects of sodium nitroprusside and nitroglycerin on tension prolongation of cat papillary muscle during recovery from hypoxia.

Because of recent studies suggesting that vasodilators affect ventricular compliance, we studied the effect of sodium nitroprusside and nitroglycerin on the mechanical performance of 21 isolated cat papillary muscles. The muscles were stimulated isometrically at 36 beats/min. Sixteen of the muscles were made hypoxic (95% N2, 5% CO2) for 50 minutes and then reoxygenated. Sodium nitroprusside (10(-5) M) added to four of these muscles prior to hypoxia substantially diminished the tension prolongation (both the time to peak tension, TTP, and time for tension to fall to 1/2 its peak value, RT 1/2) that characterizes recovery from hypoxia. TTP and RT 1/2 measured 2 minutes after reoxygenation were 300 +/- 20 msec and 528 +/- 26 msec for the control muscles compared to 208 +/- 13 msec and 248 +/- 22 msec for the muscles pretreated with nitroprusside. Nitroprusside had no effect on the fall and recovery of peak developed force or on the rise and fall of resting force. Furthermore, nitroprusside had no effect on the above parameters in nonhypoxic muscles. We also found that nitroprusside in concentrations of 10(-7) M and nitroglycerin in concentrations of 10(-5) M had little or no effect on tension prolongation. The results of the study indicate that nitroprusside is capable of blocking the tension prolongation that occurs during recovery from hypoxia and may prevent the incomplete myocardial relaxation thought to characterize this phenomenon. Since nitroglycerin had no effect on tension prolongation, it is possible that other factors also may be important in the apparent increase in left ventricular compliance associated with administration of vasodilators to patients.

Animals↗
PubMed1976

Diastolic properties of the left ventricle.

Left ventricular pressure and volume during diastole reflect the interaction of ventricular elastic, viscous, and inertial properties, and the completeness of myocardial relazation. Myocardial relaxation may be impaired in the acutely ischemic ventricle, partly accounting for the abnormal diastolic pressure-volume relation in this condition. Altered elasticity of its wall can cause increased stiffness of the ventricular chamber, as in aortic stenosis, coronary heart disease, and infiltrative cardiomyopathies. In aortic stenosis, increased left ventricular stiffness results in an increase in pressure increment associated with left atrial contraction. Generation of such a high filling pressure is critical in maintaining adequate end diastolic sarcomere stretch in the left ventricle and probably accounts for the frequent deterioration of patients with aortic stenosis after development of atrial fibrillation or nodal rhythm. Many signs and symptoms of cardiac failure, previously attributed to impaired systolic performance, may be due to partly to altered diastolic properties of the ventricular chambers.

Animals↗
PubMed1975

Assessing the hemodynamic severity of acute aortic regurgitation due to infective endocarditis.

Nine patients who underwent aortic-valve replacement for acute aortic regurgitation due to infective endocarditis were studied for clinical features that may be useful in assessing the severity of this condition. The traditional physical signs of a wide pulse pressure were absent. As compared to a group of patients with chronic aortic regurgitation, the mean (plus or minus S.D.) pulse pressure (55 plus or minus 7 vs. 105 plus or minus 22 mm Hg), left ventricular end diastolic volume (146 plus or minus 28 vs. 264 plus or minus 64 ml per square meter) and stroke volume (89 plus or minus 22 vs. 163 plus or minus 57 ml per square meter) were significantly smaller in the acute group (P less than 0.01). Left ventricular pressure exceeded left atrial pressure in late diastole, causing premature closure of the mitral valve, and the degree of early closure reflected the increase in left ventricular end diastolic pressure. Premature closure of the mitral valve was demonstrated by echocardiography in all patients. Those with echocardiographic signs of very early mitral-valve closure have severely volume-overloaded ventricles and are candidates for early valve replacement.

Acute Disease↗
PubMed1975

Alterations in preload and ejection phase indices of left ventricular performance,.

Ejection phase indices such as mean velocity of circumferential fiber shortening (V-cf), ejection fraction (EF), and mean normalized systolic ejection rate (MSER) are thought to reflect the level of left ventricular (LV) inotropic state. Although known to be influenced by changes in afterload, their response to altered preload is less certain. This question was examined in ten normal subjects studied in the supine position and after 10 min of 75 degree head-up tilt. Echo VL diameter (D) and carotid pulse recordings were used to calculate LV ejection time, V-cf, MSER, LV end-diastolic and stroke volumes (EDV and SV, by D3 formula), and ejection fraction. Systemic blood pressure (BP)was measured by cuff, and heart rate (HR) counted from the ECG. Calculated LVEDV decreased with tilt (115 plus or minus 8 to 82 plus or minus 7 ml, P smaller than 0.001), as did SV (81 plus or minus 6 to 54 plus or minus 6 ml, P smaller than 0.001), and ejection time (0.31 plus or minus 0.01 to 0.27 plus or minus 0.00 sec, P smaller than 0.001), but there was no significant change in systolic or diastolic BP or HR. V-cf, EF, and MSER were not singificantly altered by tilt (1.09 plus or minsu 0.04 to 1.12 plus or minus 0.05 circ/sec; 0.70 plus or minus 0.02 to 0.65 plus or minus 0.02; and 2.29 plus or minus 0.07 to 2.43 plus or minus 0.08 end-diastolic volumes/sec, respectively). V-cf, MSER, and EF appearrelatively unaffected by acute alterations in preload. That compensatory sympathetic responses blunted potential changes cannot be excluded, although HR was not found to have increased.

Adult↗