摘要:

Ventricular inhibited cardiac pacemakers were suppressed by intimate contact of the tip of the active pacemaker electrode with that of the inactive pacemaker electrode in two patients. This contact apparently was sensed as myocardial electrical activity and resulted in variable suppression of pacemaker emission. There was no interference with R-wave sensing function. The threshold for stimulation was unaffected. There was no loss of capture as tested with the magnet-controlled continuous mode of stimulation. This type of pacemaker failure can be remedied simply by withdrawing the tips of the electrodes from intimate contact.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Reflected ultrasound has been used for investigation of the mitral valve region in early infancy. The material consists of two patients with mitral atresia, three patients with mitral stenosis and aortic valvular atresia, five patients with mitral and aortic valvular stenosis, one patient with cor triatriatum, and one patient with severe degree of aortic valvular stenosis with a normal mitral valve. The results are compared with ultrasoundcardiographic findings in ten infants without heart disease. A specific abnormal echo was obtained in cases with mitral atresia and cor triatriatum. The patients with a combination of mitral and aortic valvular lesions could be separated into two groups by means of ultrasoundcardiography. This separation reflected the functional state of the left ventricle based on the degree of mitral stenosis and hypoplasia of the left ventricle.This noninvasive technic has been found useful as a complementary method for the investigation of the mitral valve region. It can even be performed in seriously ill infants.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

The effects of isoproterenol,l-norepinephrine, and intraaortic counterpulsation on hemodynamics and myocardial metabolism were evaluated in shock due to acute myocardial infarction. Before treatment, the cardiac index was markedly reduced, averaging 1.35 liters/min/m2. Mean aortic pressures ranged from 40 to 65 mm Hg. Decreases in coronary blood flow (mean, 68 ml/100 g/min) and in myocardial oxygen consumption (mean, 8.11 ml/100 g/min) were associated with abnormally high myocardial oxygen extractions (mean, 78%) and with lactate production (mean, 9%). Isoproterenol increased cardiac index 63% and heart rate 26%. Coronary blood flow rose an average of 12 ml/100 g/min in the face of decreased diastolic aortic pressure. Rate of myocardial lactate production increased.l-Norepinephrine increased mean aortic pressure and coronary blood flow an average of 21 mm Hg and 27 ml/100 g/min. Mean myocardial oxygen consumption rose 2.24 ml/100 g/min. While myocardial lactate production shifted to extraction (mean, 12%), myocardial oxygen extraction remained abnormally high (mean, 73%). Cardiac index did not change. Intraaortic counterpulsation increased mean aortic pressure and coronary blood flow an average of 15 mm Hg and 23 ml/100 g/min. Myocardial oxygen consumption remained essentially unchanged. Both myocardial lactate and oxygen extraction improved toward normal values (15 and 61%). Cardiac index increased an average of 0.45 liters/min/m2.Hemodynamics and myocardial metabolism then were markedly abnormal in shock due to acute myocardial infarction. Isoproterenol improved cardiac performance but myocardial oxygenation deteriorated. Therefore isoproterenol does not seem to be helpful in coronary shock.1-Norepinephrine improved myocardial perfusion and oxygenation, but did not change cardiac output. It appears to be the vasoactive agent of choice in the initial treatment of coronary shock. Intraaortic counterpulsation changed myocardial metabolism toward normal and improved systemic perfusion. Mortality remained unchanged however during the three different therapeutic interventions emphasizing the importance of early recognition of the shock state and of further aggressive diagnostic and therapeutic management.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

In a series of 1,080 consecutively monitored patients who received digoxin, arrhythmias attributed to the drug were observed in 144 cases (13.3%). The proportion of arrhythmias among 510 patients with blood group O was 10%, while for the 570 patients of groups A, B, and AB (non-O), it was 16.3% (P< 0.002). The point estimate of relative risk for non-O patients relative to group O patients with 1.7, with 95% confidence limits of 1.2 and 2.5, and the increase in the risk was most prominent between the ages of 50 and 69 years.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Left venitricular pressures were obtained in 14 patients with acute myocardial infarction, of whom seven survived. Calculated contractile element velocity (VCE), left ventricular end-diastolic pressure, and maximum dp/dt were compared with other hemodynamic measurements of LV function. VCEat 5 mm Hg (VCE5) was calculated according to the Maxwell three-component model of muscle and used as an index of overall contractile state. There was considerable overlap between survivors and nonsurvivors in the levels of VCE5, LVEDP, cardiac index, heart rate, and systemic vascular resistance. There was a reasonably good separation between survivors and nonsurvivors with measurements of mean arterial pressure, maximum LV dp/dt, mean isovolumic &Dgr;p/&Dgr;t, and stroke work. Changes in VCE5were no more sensitive after five inotropic interventions than ventricular function curves in monitoring changes in conitractile state. It is concluded that LV pressure measurements in acute myocardial infarction offer little further clinical information of importance beyond that which can be obtained from measurements of pulmonary capillary wedge pressure, arterial pressure, and cardiac output.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Twenty-one instances of nonparoxysmal junctional tachycardia (NPJT) were observed in 203 consecutive patients with acute myocardial infarction. The arrhythmia complicated both anterior and inferior wall infarction and was associated with an ominous prognosis, particularly in patients with anteror wall infarction.The NPJT is probably a manifestation of the severity of the lesion. The exact mechanisms of the enhanced A-V junctional activity remain obscure. The possible role of increased levels of epinephrine and norepinephrine and localized increases of potassium in the A-V junction from adjacent necrotic myocardium is suggested.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Systolic time intervals (STI) were measured simultaneously with left ventricular pressure, right atrial pressure, and cardiac output in patients with acute myocardial infarction (AMI) within 24 hours of the onset of symptoms. Electromechanical systole (QS2) and left ventricular ejection time (LVET) were measured and preejection period (PEP) calculated and corrected for heart rate. LVET showed significant correlation with stroke volume (r = 0.62), confirming previous observations. Patients with significantly elevated left ventricular end-diastolic pressure (LVEDP) and clinical signs of congestive heart failure (CHF) usually exhibited a prolonged PEP when compared with normal subjects or patients with AMI who did not have signs of CHF. The normal PEP in the latter group might be due to adrenergic stimulation offsetting the effect of myocardial damage, although measurements of circulating catecholamines did not conclusively support this hypothesis. We conclude that STI are not reliable indices of left ventricular performance in AMI.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Microangiographic examination of the pulmonary arterial system in 12 newborn infants with concomitant stenosis or atresia of the aortic and mitral orifices showed that the intrapulmonary arterial pattern is influenced by the state of the foramen ovale. In infants with aortic atresia with a prematurely closed foramen ovale, that is cases in which the left side of the heart is a cul-de-sac, there is moderate or prominent tortuosity of the intralobular pulmonary arteries indicating congenital pulmonary hypertension. This feature is less prominent or absent in infants with valvular insufficiency of the foramen ovale, regardless of the postnatal age of the patient.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Left heart volume characteristics were evaluated by using biplane cineangiocardiography in 18 studies in 15 patients with total anomalous pulmonary venous connection (TAPVC) and in 37 studies on 35 patients with large secundum or sinus venosus atrial septal defects (ASD). Left ventricular end-diastolic volume (LVEDV) was decreased to less than 67% of normal in five of 15 preoperative TAPVC patients, but the average value for the entire group was not significantly different from normal. In ASD patients, the average LVEDV was 87% of normal which was significantly decreased (P< 0.001). The ejection fraction was decreased from normal in patients with TAPVC and ASD who were less than 2 years of age (0.62 vs. 0.68,P< 0.01), but was normal in older patients. Left ventricular systolic output was significantly decreased from normal in both TAPVC (75% of normal,P< 0.001) and ASD patients (81% of normal,P< 0.001). Left atrial maximal volume was significantly decreased from normal in TAPVC patients averaging only 55% of normal (P< 0.001), but was normal in eight ASD patients. All volume variables increased following corrective surgery in two TAPVC patients and two ASD patients. These studies document that left heart volumes and outputs in infants and children with TAPVC and large isolated atrial defects can be diminished preoperatively.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Clinical data on 12 patients under 6 months of age are presented together with the necropsy evidence of truncus arteriosus. Five patients had normal truncal valves and seven had markedly deformed and incompetent valves. Among the group of infants with truncal valve insufficiency, the cause of death was refractory congestive heart failure in each instance, whereas the patients with normal truncal valves succumbed from other causes.Pathologic examination of the abnormal truncal valves revealed cusps which were thickened by fibrous nodules. Combined heart-lung weight in patients with deformed truncal valves had a mean increase of 85% above normal values, while in the group of patients with normal truncal valves the mean increase was 17%. Similar results were observed when liver weights were compared.The major clinical findings among the group of patients with truncal insufficiency were bounding peripheral arterial pulses, early diastolic decrescendo murmurs, and congestive heart failure which was refractory to medical treatment and, in one instance, surgical palliation. It is suggested from the data that deformities of the truncal valves are a primary cause of early mortality among infants with truncus arteriosus.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID