ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

To investigate the relationship between alterations in lung mechanics and acute pulmonary vascular congestion, repeated measurements of the respiratory system impedance (Zrs) were performed in 11 patients with and in seven without acute left ventricular failure. Indexes of Zrswere obtained by calculating the average and slope of the resistance and reactance in low (10 to 20 Hz) and high (20 to 50 Hz) frequency intervals. Zrsindexes in patients with ventricular failure differ significantly from those in patients without failure. Pulmonary vascular congestion is regularly associated with an abnormal frequency dependence of resistance at low frequencies and with an increased resonant frequency. Discriminant analysis of Zrsindexes allows 92% correct classification of pulmonary capillary wedge pressures lower than and those equal to or higher than 18 mm Hg. Zrsdifferences between patients with and without left ventricular failure are consistent with the presence of a small airways obstruction even in patients with mild left ventricular failure. Furthermore, use of Zrsindexes permits moderate and severe pulmonary vascular congestion to be distinguished from one another and this is probably due to a significant narrowing of the large airways during severe left ventricular failure.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Diminished glomerular filtration rate, proteinuria, and large hypercellular congested glomeruli with segmental sclerosis are found in late survivors with cyanotic congenital heart disease (CCHD). Hyperuricemia is common, acute gouty arthritis is less common than uric acid levels would predict, and overt tophaceous deposits of uric acid are exceptional. The role of the kidney in causing the basic biochemical disturbances, and the relative importance of impaired urate excretion vs urate overproduction have not been established. Accordingly, we reviewed the courses of two index patients and prospectively studied eight additional CCHD patients from 28 years to 46 years old with mean hematocrits of (62 ± 10%). Plasma creatinine concentration was normal (0.9 ± 0.1 mg/dl) yet glomerular filtration rate was mildly reduced to 93 ± 14 ml/min as measured by creatinine clearance and to 81 ± 6 ml/min as measured by111In DTPA. Three patients had significant proteinuria and one was nephrotic. Plasma uric acid concentration was high in all but one (8.2 ± 2.1 mg/dl), mean 24 hr uric acid excretion was normal (564 & 221 mg), and fractional uric acid excretion was relatively low (6.3 ± 2.6%). The two patients with highest plasma uric acid levels (12.0 and 10.2 mg/dl) had the lowest fractional excretions (2.8% and 4.0%). Both of these patients had diminished capacity to excrete a water load (38% and 27%/4 hr) and to maximally concentrate urine (520 and 635 mOsm/kg after water deprivation and vasopressin). In conclusion, high plasma uric acid levels in late survivors with CCHD are secondary to inappropriately low fractional uric acid excretion, not to urate overproduction. Hyperuricemia serves as a marker of abnormal intrarenal hemodynamics. Enhanced urate reabsorption appears to result from renal hypoperfusion reinforced by a high filtration fraction.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Twenty-four hour noninvasive ambulatory blood pressure and heart rate monitoring was performed on patients who underwent orthotopic cardiac transplantation, as part of the investigation of the de novo hypertension that developes in such patients. Patients with essential hypertension served as control subjects. The results demonstrated a highly significant loss of the usual decline in blood pressure and heart rate during sleep in the transplant patients. A similar loss of nocturnal decline in blood pressure was noted in a group of 10 patients with autonomic neuropathy secondary to diabetes mellitus. The de novo hypertension associated with cardiac transplantation is probably multicausal. Impairment of renal function by cyclosporin-A with associated salt and water retention and persistent elevation of the systemic vascular resistance in the presence of a restored normal cardiac output by the “new” heart are major factors. In addition, loss of the normal nocturnal decline in blood pressure and heart rate, which probably is related to the denervated state of the transplanted heart, may play an important role in blood pressure control.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Peripheral vascular resistance (PVR) and thromboxane A2(TxA2) synthesis after the cold pressor test were investigated in different subsets of patients with angina (10 with stable effort angina, 36 with resting angina [24 in an active phase and 12 in an inactive phase], and five with Prinzmetal's variant angina) and in 41 control subjects of equivalent age and risk factors. Left ventricular end-diastolic pressure, ejection fraction, extent of coronary angiographic lesions, and baseline PVR were not significantly different among the various patient groups. In all patient groups, except those with variant angina, the cold pressor test resulted in a higher increase in PVR than in the control subjects (p < .001 for all groups). In patients with variant angina the vasoconstrictor response was increased only in proximity (about 1 hr) to ischemic attacks. In patients with active resting angina the vasoconstrictor response was on the average four times longer than that in patients with effort angina and with inactive resting angina (p < .001). This exaggerated vasoconstrictor response was associated with elevated TxA2 resting levels in plasma and with increased TxA2synthesis after the cold pressor test. A linear relationship was found between the area of the vascular response and the area of TxA2production after the cold pressor test in patients with active resting angina (r = .87, p < .001). The increased TxA2synthesis and the inappropriate increase of peripheral vascular response to sympathetic stimulation revert back to normal in the inactive phase. These alterations might contribute to the occurrence of inappropriate vasoconstriction and of the abnormal vascular responsiveness to various stimuli frequently found in patients with unstable angina.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

A specific search for intramyocardial platelet aggregates was made in 90 patients who died suddenly of ischemic heart disease. Platelet aggregates in small intramyocardial vessels were found in 27 (30%). There was a significant difference (p < .05) in the incidence of platelet aggregates in patients with chest pain of recent onset (unstable angina) before death (16/36, 44.4%) and that in those without it (11/54, 20.4%). Multifocal microscopic necrosis with involvement of the full thickness of the ventricular wall, including the subpericardial zone, was significantly more common (p = < .005) in the patients with platelet emboli (55.6% vs 12.7%). With one exception, aggregates were confined to the segment of myocardium immediately downstream of a major epicardial coronary artery containing an atheromatous plaque that had undergone fissuring and on which mural thrombus had developed. The results support the view that platelet aggregates in the myocardium represent an embolic phenomenon and are a potential cause of unstable angina. The association of myocardial necrosis with such emboli could precipitate sudden death from ventricular fibrillation.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The objective of this study was to determine the constraining effect of the normal human pericardium. Accordingly, immediately after thoracotomy in nine patients undergoing elective cardiac surgery, we measured mean pericardial surface pressure over the lateral free wall of the left ventricle with a flat balloon as well as mean right atrial pressure while incrementally infusing up to 2.1 liters of Ringer's solution to increase right atrial pressure. In each case, the slope of the relationship between right atrial (range − 4 to 20 mm Hg, overall) and pericardial pressures was near unity (1.16 ± 0.20 mean ± SD) and the intercept was approximately zero (0.71 ± 2.48 mm Hg). Correlation coefficients ranged from .86 to .97. These observations suggest that right atrial pressure can be used as an estimate of pericardial surface pressure. If this is the case, true left ventricular preload (i.e., effective distending pressure or transmural diastolic pressure) might be estimated from the difference between left ventricular filling pressure and right atrial pressure, both conveniently measurable clinically by means of a triple-lumen, flow-directed catheter.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

A physiologic means of measuring the distribution of cardiac output and regional myocardial blood flow has been developed that uses human albumin microspheres labeled with carbon-11 (11C) and external detection with positron emission tomography. Ten patients with previous myocardial infarction were studied to investigate the level of blood flow in normal and infarcted segments of the heart. After diagnostic catheterization, 4 to 6 mCi of11C on 2 to 3 million sterile microspheres (15 to 20 μm) were mixed and injected into the apex of the left ventricle during timed withdrawal of arterial blood to obtain reference flow values. Regional activity in brain, heart, lungs, liver, spleen, and kidneys was measured tomographically. Blood flow was calculated based on the relationship between total activity in a reference flow and tissue activity in tomograms of each organ (ml/min/100 g). No adverse effects were noted after injection of the microspheres. Successive myocardial tomograms showed no loss of activity. There were no significant differences in flow values in matched regions of paired organs. Mean cerebral flow was 52.4 ± 10.0 ml/min/100 g in the frontal lobes, 54.4 ± 8.8 in the temporal lobes, 67.6 ± 8.2 in the occipital lobes, and 53.0 ± 9.4 in the basal ganglia. Flow was 16.0 ± 8.4 ml/min/100 g (range 0 to 40.0) in the center of infarcted myocardium and 82.0 ± 32.0 in the remote segments. This method meets most of the demands for use of microspheres to measure tissue blood flow. The wide range of flow values in infarcted myocardium may be a function of infarct size, spatial resolution, or pathologic evidence of islands of viable tissue. Patients with angina had high flow values in the infarcted segment, whereas those with heart failure had significantly lower values. Surviving myocardium in the region of the infarct may need to be considered if patients complain of angina, particularly when treatment is aimed at preserving ventricular function.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

An ideal coronary vasodilator for studying coronary flow reserve in humans would rapidly produce maximal coronary vasodilation, be short acting to permit repeated measurements, and not alter systemic hemodynamics. The two commonly used vasodilators (dipyridamole and meglumine diatrizoate) do not satisfy these criteria; meglumine diatrizoate does not produce maximal hyperemia and dipyridamole has a long duration of effect (greater than 30 min). In this study we used a subselective coronary Doppler catheter to measure the dose-response kinetics of a shorter acting vasodilator, intracoronary papaverine. In 10 patients with normal coronary vessels, the maximal vasodilator response to papaverine was compared with that to intravenous dipyridamole (0.56 mg/kg infused over 4 min) and intracoronary meglumine diatrizoate. The increase in coronary blood flow velocity after the maximal dose of papaverine (4.8 ± 0.4 peak/resting velocity ratio, mean ± SEM) was nearly identical to that seen after infusion of dipyridamole (4.8 ± 0.6) and was significantly greater than that after meglumine diatrizoate (3.1 ± 0.2, p < .01). At maximal hyperemia, mean a rterial blood pressure fell 9 ± 2% (mean ± SEM) after intracoronary papaverine, 8 ± 4% after dipyridamole, and 3 ± 3% after meglumine diatrizoate. The dose-response kinetics of intracoronary papaverine were studied in 13 patients with normal coronary arteries. In the left coronary artery, maximal vasodilation (5.4 ± 0.6) was achieved with 8 mg in six of eight patients and with 12 mg in all patients. In the right coronary artery, maximal vasodilation (4.8 ± 0.7) was achieved with 6 mg in four or five patients and with 8 mg in all patients. Onset of maximal vasodilation was rapid after papaverine (16 ± 1 sec) and meglumine diatrizoate (15 ± 1), but prolonged after dipyridamole (4.8 ± 0.4 min after onset of infusion). The duration of maximal vasodilation was brief after papaverine (49 ± 10 sec) and meglumine diatrizoate (8 ± 1 sec), but prolonged after dipyridamole (greater than 4 min). Coronary blood flow velocity returned to within 10% of resting values quickly after papaverine (128 ± 15 sec) and meglumine diatrizoate (42 ± 4 sec). After dipyridamole infusion, however, coronary blood flow velocity remained elevated for greater than 4 min after completion of infusion. These results suggest that papaverine can produce intense, rapid-acting vasodilation of the coronary arteriolar bed equivalent to that stimulated by intravenous dipyridamole without markedly altering systemic arterial pressure. Although the extent and duration of vasodilation was dose dependent, the hyperemic period in all patients was sufficiently brief to allow multiple measurements of coronary reserve over a short period of time. The use of intracoronary papaverine to measure the maximal flow reserve capacity of individual coronary vessels should greatly facilitate studies of the coronary circulation in patients undergoing cardiac catheterization

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Laminar flow through a conduit is equal to the mean velocity times the cross-sectional area of the orifice. Therefore, volume is equal to the time-velocity integral multiplied by the crosssectional area. In aortic stenosis, flow in the stenotic jet is laminar and the aortic valve area should be equal to the volume of blood ejected through the valve divided by the time-velocity integral of the aortic jet velocity recorded by continuous-wave Doppler echocardiography. To test whether this concept can be used to accurately determine aortic valve area noninvasively by the Doppler method, 39 patients (age 35 to 82 years, mean 63) underwent pulsed Doppler combined with two-dimensional echocardiography for measurement of stroke volume at the aortic, pulmonic, and mitral anulus as well as continuous-wave Doppler recording of the aortic jet. Aortic valve area determined at cardiac catheterization by the Gorlin equation ranged between 0.4 and 2.07 cm2(mean 0.89 ± 0.45). Doppler-derived valve area, determined with the stroke volume value from either the aortic, pulmonic, or mitral anulus, correlated well with the area determined at cardiac catheterization (r = .95, .97, and .96, respectively). A simplified method for measuring aortic valve area derived as the cross-sectional area of the aortic anulus times peak velocity just proximal to the aortic valve divided by peak aortic jet velocity correlated well with measurements obtained at cardiac catheterization (r = .94). An excellent separation between critical and noncritical aortic stenosis was seen using either one of the Doppler methods. Thus, combined pulsed and continuous-wave Doppler can be used to accurately measure valve area in adult patients with aortic stenosis.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID