摘要:

Glucose extraction by ischemic human myocardium was investigated at the time of diagnostic cardiac catheterization in 27 subjects who had fasted overnight. Paired arterial and coronary sinus blood samples, obtained before and during coronary sinus pacing, were analyzed for glucose and lactate. Pacing to a rate 50 to 70% greater than control or to the development of chest pain induced no significant change in the arterial level of either substrate. No correlation was noted between arterial level and myocardial extraction of either substrate at rest or during stress.Three groups of subjects were identified: group I: those with lactate extraction at rest and during pacing (n = 13); group II: those with lactate extraction at rest but production during pacing (n = 7); and group III: those with lactate production at rest with augmented production during pacing (n = 5). Two additional subjects produced lactate at rest but were not paced. Glucose extraction increased significantly with pacing tachycardia in group II (0.09 ± 0.03 mM to 0.26 ± 0.04 mM) and in group III (0.38 ± 0.17 mM to 0.58 ± 0.12 mM). No significant increase was noted in group I. A significant correlation was noted between glucose extraction and lactate production during pacing when groups II and III were combined (r = 0.81;P< 0.001).Myocardial ischemia in man was associated with augmented glucose extraction. The arterial glucose concentration was not a primary determinant of glucose extraction either before or during induced ischemia.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

The effect of levodopa on the externally recorded preejection period (PEP), blood pressure, and heart rate was evaluated in patients with Parkinson's disease during the first 2 weeks of therapy and after 3 months of continuous therapy. During the same time periods, the response of these parameters to graded intravenous doses of dopamine and epinephrine was determined. During the first 2 weeks, levodopa (1.0 and 1.5 g) produced a dose-related shortening of the PEP which was maximal at the time of the 30 or 60-min recordings and remained significant (P< 0.05) for 90 min following the 1.0-g dose and for 120 min after the 1.5-g dose. The drug had no effect on heart rate and reduced arterial blood pressure minimally. Propranolol (10 mg by mouth) prevented the shortening of PEP produced by levodopa. After 3 months of therapy, levodopa (1.5 g) failed to shorten the PEP significantly. However, the effect of dopamine and epinephrine on PEP was not significantly different from that obtained during the first 2 weeks of treatment with levodopa. It is concluded that levodopa exerts a positive inotropic effect which is mediated via beta-adrenergic receptors and that tolerance develops by 3 months of continuous administration. The tolerance does not appear to be caused by impaired responsiveness of the heart since the effect of graded doses of dopamine and epinephrine on the PEP was similar during both acute and chronic administration.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Myocardial electrolyte balance and hemodynamics were studied in 14 patients before and after the administration of ouabain. The drug caused a significant loss of potassium from the myocardium. This was accompanied by a significant positive inotropic response, indicated by an increase in the rate of rise of left ventricular pressure and systolic ejection-rate index. Heart rate, cardiac output, left ventricular end-diastolic pressure, brachial artery pressure, and left ventricular stroke-work index remained unchanged. These observations in man are compatible with those theories of digitalis action which associate inotropic effect with the inhibition of membrane sodium- and potassium-activated adenosine triphosphatase.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

In an epidemiologic study of 1,118 free-living volunteers, aged 25 to 79 (552 male, 566 female) drawn from eight counties of the Central Valley, California, the following determinations were included: a medical history, blood pressure, resting electrocardiogram, plasma total cholesterol and glycerides (following a light, fat-free breakfast), and (when lipids were considered to be elevated) plasma lipoproteins determined by electrophoresis. A subgroup of the entire study population (494 male, 503 female) free of overt diabetes and electrocardiographic abnormalities, and with diastolic blood pressure not above 100 mm Hg, that was considered to be clinically “normal,’ forms the basis of this report.Significant sex differences for mean levels of total cholesterol were absent or of small magnitude at all age decades up to and including the seventh. In contrast, glyceride levels for men were significantly higher than for women aged 25-59, and differences were substantial. Beyond the seventh decade, females had higher mean levels of both plasma total cholesterol and glycerides.The type IV lipoprotein pattern was the most common abnormality (8.6%) within the entire normal population and was 2.7 times as common in men (13%) as in women (4.8%). Type II pattern was less common overall (3.7%) and was more frequent in women than in men. Types III (0.2 to 0.4%) and V (0.2%) were both very uncommon, and type I was not encountered. Results were similar when the entire population (normal and abnormal) was considered.These findings suggest that sex differences in plasma total-cholesterol level cannot account for the known male preponderance in coronary heart disease within the population studied. Prolonged elevation of plasma glycerides (usually expressed as the type IV pattern) in males during the years when atherogenesis is occurring might account for the sex difference.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Twenty-two patients with shock complicating myocardial infarction were studied hemodynamically and, despite pharmacologic therapy and regulation of intravascular volume, 16 (73%) subsequently expired. Pulmonary artery end-diastolic pressure (PAEDP) or left ventricular end-diastolic pressure (LVEDP) was > 15 mm Hg in 18 of the 22 patients, and cardiac index (CI) was ≤2.3 liters/min/m2in 17 of 22 patients. Fourteen of the 18 patients with PAEDP or LVEDP > 15 mm Hg expired, while two of the four patients with a PAEDP or LVEDP < 15 mm Hg survived. Thirteen of 15 individuals with a CI < 2.3 liters/min/m2died, and four of seven with a CI ≤ 2.3 liters/min/m2survived. A ventricular gallop (S3) was audible in 15 patients with PAEDP or LVEDP varying from 13 to 60 mm Hg. In 11 patients with an S3who expired, the PAEDP or LVEDP ranged from 22 to 60 mm Hg. Mean peripheral vascular resistance was 41.3 units in survivors and 67.8 units in nonsurvivors. Six of eight patients who did not survive the period of hospitalization had a depressed response to dextran infusion manifested by a greater increase in PAEDP or LVEDP than in CI.Hemodynamic evaluation permitted early identification of measurements associated with 100% mortality despite intensive medical treatment. These findings included: (1) PAEDP or LVEDP > 28 mm Hg and (2) PAEDP or LVEDP > 15 mm Hg in association with a CI < 2.3 liters/min/m2. Patients in cardiogenic shock with these hemodynamic alterations are presumably candidates for cardiocirculatory mechanical assisting devices and possibly for further surgical intervention.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

The phenomenon of postpacing depression of cardiac pacemakers was utilized to evaluate the sinus-node function in 56 patients by analyzing the sinus-node recovery time (SRT), that is, the interval between the last paced P wave and the following sinus P wave. Corrected SRT (CSRT) is defined as the recovery interval in excess of the sinus cycle (SRT — sinus cycle length). The SRT was measured following sinus-node suppression by (1) isolated premature beats (PABs) and (2) atrial pacing (AP) at rates of 100 to 140/min for periods of 2 to 5 min at each level. Twenty-eight patients had normal heart rates (group A), and 28 patients had sinus bradycardia (SB; group B). Ten of the 28 patients with SB were restudied after receiving atropine (2 mg intravenously). The CSRT with PABs was similar in both group A and group B patients and remained essentially unchanged after atropine despite a decrease in sinus cycle length. The phenomenon of interpolated PABs was demonstrated in seven of the 56 patients. In 27 of the 28 patients with normal heart rates (group A), the CSRT with AP ranged from 110 to 525 msec and was essentially independent of the rate and duration of AP. In the remaining one patient of group A, despite a normal heart rate, the CSRT was prolonged (1810 msec) and directly dependent on the rate and duration of AP. In 12 of the 28 patients with SB, the CSRT was comparable to that in group A (≦525 msec). In the remaining 16 patients with SB (group B), the CSRT ranged from 560 to 3740 msec and was usually directly proportional to the rate and duration of AP. After atropine in most of the patients with a prolonged CSRT, the CSRT remained abnormal whereas in others junctional escape beats appeared first, followed eventually by normal sinus rhythm. In a single patient with SB and an abnormal CSRT, restudy 7½ months later again showed a prolonged CSRT indicating the reproducibility of the measurement. The CSRT with AP provides a potentially useful clinical means of assessing the sinus-node function and thereby aids in the diagnosis of the “sick sinus syndrome.’ It is stressed that AP was found to be more reliable than PABs in eliciting an abnormal response. Furthermore, a normal sinus (atrial) rate does not necessarily provide assurance of a normal sinus-node response to AP, that is, normal sinus-node function.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Fourteen children who had been operated on for partial anomalous pulmonary venous return from the right lung to the vena cava or right atrium have been submitted to a follow-up study 1 to 9 years after surgery. This included clinical, hemodynamic, and angiographic data. All patients were doing well and had normal exercise tolerance at the time of follow-up examination. Electrocardiograms and chest roentgenograms had returned to normal in 10 and were improved in three. Hemodynamic and angiographic data demonstrated perfect correction in eight. Of the remaining six, three had an obstructed superior vena cava (SVC) with collateral pathways to a persistent left superior vena cava in two and to the inferior vena cava in one. Three had significant pressure gradients between the SVC and the right atrium, two with a small right-to-left shunt from the SVC to the left atrium, and one with an additional small left-to-right shunt. None had obstruction to the pulmonary venous return. These complications occurred exclusively in cases in which at least one anomalous vein drained high into the superior vena cava. Enlargement of the SVC with a patch of pericardium gave good results in three patients with this type of anomalous drainage but did not prevent obstruction or severe narrowing of the SVC in two other cases. It is concluded that the present corrective technics are not adequate for cases in which an anomalous vein drains high in the SVC, especially in the presence of a left superior vena cava.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Fleischner lines are often the only roentgen evidence of pulmonary embolization, particularly when the emboli are small. The linear shadows are cast by focal areas of atelectasis viewed on end. The atelectasis is an indirect manifestation of the vascular occlusion and is due to obstruction of a subsegmental bronchus by retained secretion or by hemorrhagic exudate. Although Fleischner lines are not seen in every case of pulmonary embolization, when present, and especially when bilateral, they are definitely suggestive of the diagnosis.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

It has been estimated recently that half of deaths among the patients with acute myocardial infarction occur before they ever reach the hospital for definitive medical care. One of the major reasons for the high incidence of death was attributed to delays in reaching medical care, involving patients themselves, physicians, transportation, and receiving areas of the hospital. In order to reduce this high mortality substantially we should focus our attention on the prehospital care of this disease, which may include several major approaches.A. To shorten the delay in securing medical care:1. Public education, with emphasis on the early warning symptoms and signs of acute myocardial infarction, and the need and importance of seeking early medical care, with special attention directed toward the high-risk coronary patients.2. Professional education.3. Mechanisms to direct and/or bring patients with suspected or proven acute myocardial infarction promptly to the system of medical care with special emphasis on the utilization of a telephone information center and provision of rapid transportation.B. Establishment of emergency life-support stations for screening, monitoring, and early stabilization of cardiac arrhythmias:1. Fixed.a. Emergency department of hospitals, preferably with an attached precoronary care area.b. Areas where many employees are working on weekdays.c. Areas where many people move in and out from day to day.d. Areas where there is periodic concentration of mass population.2. Mobile.a. Mobile coronary care unit.b. Mobile intensive care unit.C. Prevention of sudden death:1. Study of mechanism and clinical environment of sudden death.2. Development of techniques for early diagnosis and management of acute myocardial infarction prior to inception of symptoms.3. Identification of individuals prone to sudden death.4. Preventive measures directed toward the individuals prone to sudden death.a. Effective control of risk factors.b. Intermittent or periodic electrocardiographic monitoring in these individuals.c. Long-term antiarrhythmic therapy for these individuals.d. Possibility of implanting an automatic defibrillator in patients with previous myocardial infarction or in those recovered from ventricular fibrillation.5. Early administration of antiarrhythmic drugs in patients with suspected or proven acute myocardial infarction.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID