ISSN:0009-7322    

出版商:OVID    

年代:1969

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

A formidable array of practical problems must be solved at laboratory level before tolerance induction in organ transplantation can be considered a realistic clinical possibility. I believe it is too early for even tentative human experimentation in this field. However, the work of the last decade has shown unequivocally that even adult animals can readily be rendered tolerant of evenexceedingly powerfulantigens. The principle of tolerance has such great specificity and such compelling elegance when compared with present-day aids to organ transplantation that intensive effort must go into harnessing it to clinical use. It will certainly enter the clinical homograft scene within a decade, and xenografts are inconceivable in its absence.

ISSN:0009-7322    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

A technique for the routine recording of His bundle (H) activity in man using a bipolar or multipolar catheter is described. The recording catheter is inserted percutaneously, via the Seldinger method, into the right femoral vein and advanced fluoroscopically into the right atrium. Placement of the pre-formed curve at the catheter tip across the tricuspid valve in nine patients resulted in stable recordings of His bundle activity in successive cardiac cycles. Right atrial pacing resulted in progressive lengthening of the P-H interval with increasing frequency but the H to S-wave interval remained constant at all rates. Similar lengthening of the P-H interval was produced during atrial pacing when pressure was applied to the carotid sinus. The use of this recording technique in man will facilitate diagnostic interpretation of the electrocardiogram and can be used in various investigations of atrioventricular and intraventricular conduction in man.

ISSN:0009-7322    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

The recent development of the instantaneously sensing Anger scintillation camera, capable of recording wide-field radioisotope images from the precordium, and a system for video storage and analysis has provided a means of visualizing the anatomic and hemodynamic features of the heart and great vessels without the hazards involved in introducing a radiopaque agent. Sodium pertechnetate (99mTcO4-) produces no cardiocirculatory effects or untoward actions and delivers only 0.13 rads of total body radiation. Following injection, the rapidly changing distribution of radioactivity within the heart is recorded by the scintillation camera-television system which includes no inherent dead time or overlap of the scanned field from frame to frame. Video tape replay is available immediately and sequential integrated pictures are possible at any rate up to 60 sec. Radioisotope images of longer intervals are easily obtained by the integration of successive stop-action fields reproduced on a high resolution television monitor and photographed on rapidly developed film. In addition, the replay may be gated and tracked, allowing selected phases to be integrated and time-concentration curves of blood flow.Five to 10 millicuries of99mTcO4-in 2 to 8 cc were rapidly injected into selected cardiac chambers at the time of diagnostic catheterization in 50 patients with a variety of congenital and acquired forms of heart disease. Movement of radioisotope closely reflected the hemodynamic alterations caused by these conditions, as determined by standard contrast angiocardiography. The radioisotope-angiocardiogram provides a new approach for visualization of the cardiovascular system, does not require the use of radiopaque medium, is safer than angiography, and does not disturb circulatory function.

ISSN:0009-7322    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

Experiments were performed in anesthetized dogs to study some effects of propranolol, dextro-propranolol and ICI50,172 on digitalis-induced arrhythmias and digitalis-induced sensitization to electrical shock. When given in beta-blocking doses, propranolol did not abbreviate ouabain-induced ventricular tachycardia (VT) or decrease ouabain-induced sensitization to electrical shock. In larger doses, propranolol first controlled the arrhythmia without affecting shock sensitivity and then abolished both arrhythmia and shock sensitivity. Dextro-propranolol, a compound with nonspecific antiarrhythmic action equal to that of propranolol but with virtually no beta-blocking effect, abolished shock sensitivity, whereas ICI50,172, a pure beta-blocking agent, did not. Beta-blocking doses of propranolol given to dogs bordering on digitalis toxicity but in normal sinus rhythm caused recurrence of sustained ventricular tachycardia. Reappearance of toxicity appeared to be related to a propranolol-induced decrease in heart rate, since it was averted during continuous electrical pacing of the atrium and reversed by isoproterenol administration.

ISSN:0009-7322    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

The intravenous administration of 3 or 5 mg of glucagon to 13 patients with heart disease resulted in a statistically significant increase in heart rate, cardiac index, stroke power index, mean rate of left ventricular ejection, and maximum rate of rise of left ventricular pressure, whereas systemic vascular resistance declined. A moderate increase in mean stroke volume index and stroke work index and a slight fall in left ventricular end-diastolic pressure also occurred, although these changes were not statistically significant. The increase in cardiac index averaged 19%, with nine of the patients demonstrating an increase exceeding 10% of their respective control value. These effects of glucagon generally reached a maximum within 15 min after drug administration and also were of short duration.Positive inotropic and chronotropic effects of glucagon were observed in most but not all of these patients. In addition, the magnitude of these effects varied considerably among patients; the variation, however, did not appear to be related to the severity or duration of the heart disease.In eight patients, the infusion of isoproterenol produced greater increases in cardiac index and decreases in left ventricular end-diastolic pressure than glucagon did.Although the effect of glucagon was short, the frequent improvement in hemodynamics which occurred in the absence of significant side effects, notably arrhythmias, indicates that the inotropic actions of this agent may be useful under certain clinical conditions.

ISSN:0009-7322    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

Sudden intravenous injections of small amounts of angiotensin or phenylephrine were given to 30 subjects to produce modest, brief increases in directly measured systemic arterial pressure. A plot of each systolic pressure against the second succeeding cardiac cycle length produced a linear distribution, the slope of which was expressed as the millisecond increase in cycle length per mm Hg rise in systolic pressure. The slope is an index of baroreflex sensitivity and was found to have an average value of 12.8 in 18 subjects without hypertension and 2.8 in 12 others with hypertension. When all results were pooled, there was an inverse relationship between the resting mean arterial pressure and slope of the baroreflex regression lines. The findings demonstrate reduced sensitivity of the baroreflexes in hypertension, with respect to control of heart rate. A distinction is made between this change in sensitivity and simple resetting of the reflex.

ISSN:0009-7322    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

Five young normal subjects (NS) and six middle-aged patients with chronic, low-output, congestive heart failure (HFP) were studied before and after 10 minutes of exposure to hypovolemia induced by negative pressure (30 mm Hg) applied to the lower body. ECG, respirometer, and catheters placed in the subclavian artery and superior vena cava permitted measurements of heart rate (HR), respiration rate, arterial and central venous pressures (CVP), and cardiac output (CO). In the group of NS, systemic vascular resistance (SVR) rose moderately, while CVP fell 4.3 mm Hg; CO, stroke volume (SV), stroke work (SW), and central blood volume (CBV) fell about 20%, whereas blood pressure and HR showed little change. In the group of HFP, control hemodynamic values were generally abnormal. In four patients the response to hypovolemia was similar to that of NS. Two patients with advanced heart failure showed no change or a rise in CO, SV, and SW in the face of a fall in CVP (3.1 and 3.7 mm Hg), no change or a fall in SVR, and a rise in CBV. It is concluded that HFP does not respond to hypovolemia in a consistent manner. Certain patients with advanced failure demonstrated abnormal responses to induced hypovolemia, the causes for which are complex.

ISSN:0009-7322    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

Immediate hemodynamic improvement in patients with complete heart block occurs when the ventricular rate is increased by electrical pacing. During pacing, there is reduction in the pulmonary artery wedge, right atrial, and left and right ventricular filling pressures. The mean rate of ejection, stroke volume, and stroke work decreased following pacing, whereas the ejection time per minute increased, and dye curves assumed a more normal configuration. Very little change was noted in the resting cardiac output.The paced heart is able to obtain greater increases in cardiac output, stroke volume, and mean rate of ejection during exercise than when unpaced. In addition, pacing tends to return elevated exercising filling pressures in the right and left ventricles toward normal.

ISSN:0009-7322    

出版商:OVID    

年代:1969

数据来源: OVID