ISSN:0009-7322    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

The evidence supporting the thesis that hypertension can be prevented by eliminating salt from the diet is based on four principal sources: (1) epidemiological studies in unacculturated peoples showing that the prevalence of hypertension is inversely correlated with the degree of salt intake; (2) hemodynamic studies suggesting that the development of chronic experimental hypertension is a homeostatic response to a maintained increase in extracellular fluid volume (ECF); (3) evidence that the ECF of “salt eaters” is expanded in comparison to that of “no-salt eaters”; and (4) investigations in hypertensive patients receiving either diets greatly restricted in salt or continuous diuretic therapy which correlate the fall in blood pressure with a reduction in ECF. Although this mechanism of essential hypertension is still obscure the evidence is very good if not conclusive that reduction of salt in the diet to below 2 g/day would result in the prevention of essential hypertension and its disappearance as a major public health problem.

ISSN:0009-7322    

出版商:OVID    

年代:1976

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

Eighteen of 388 patients with chronic bundle branch block, studied electrophysiologically and followed prospectively, had H-V intervals of 80 msec or greater. Five patients were functional class 1, five class II, seven class III, and one class IV. Follow-up ranged from 103 to 1919 days (mean 711 ± 118). Three patients needed permanent pacing for the following indications: sino-atrial block, sinus bradycardia post-cardiac surgery, and 2° block distal to the His bundle. Six patients died, three suddenly, and three nonsudden. The five initially asymptomatic patients are alive and without pacemakers (mean follow-up 732 ± 139 days).Although marked H-V prolongation was associated with high morbidity and mortality in this small series, this was only in patients with symptomatic heart disease. Asymptomatic patients (five patients) had a benign clinical course. Prophylactic pacing would probably not modify clinical course in the former group, and is probably not indicated in the latter group. Longer follow-up will be needed for definitive prognosticatio.

ISSN:0009-7322    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

Bipolar electrograms were recorded from five to six sites on the septal right bundle branch (RBB) using a multielectrode patch in ten mongrel dogs. Antegrade activation was recorded along the right bundle during sinus rhythm and during right atrial pacing at varying heart rates. Retrograde activation was produced by pacing from right ventricular epicardium. Right bundle conduction velocities varied from 1.4 to 3.3 m/sec (mean 2.0 m/sec) for antegrade conduction and from 1.8 to 2.7 m/sec (mean 2.1 m/sec) for retrograde activation. Varying degrees of conduction delay were elicited by premature stimulation and mechanical pressure to the right bundle. The conduction delays occurred over small segments of the right bundle branch with regeneration of normal propagation velocity distal to the region of block. The conduction delays were associated with fragmentation of the RBB electrograms with initiation of delayed activation waves which traveled variable distances antegrade and retrograde. These data show that stress-induced longitudinal dissociation may produce delayed activation waves within the right bundle branch which may simulate re-entrant arrhythmias.

ISSN:0009-7322    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

The relationships among the His bundle, the origin of both bundle branches, and the interventricular (IV) septum were examined histologically in 32 human hearts, and the entire bundle branch systems were delineated in 13 of these. The His bundle in five hearts traversed the right IV septal crest, and the LBB origin was a very narrow stem (maximum 1.5 mm in cross-section) crossing from right to left through the inferior margin of the membranous septum. Proximal LBB anatomy was extremely variable, demonstrating multiple fiber groups which fanned out over the entire left septal surface. The LBB did not divide into two discrete divisions without multiple interconnections. The RBB formed an obtuse angle with the His bundle in 27 of 32 hearts. In those five hearts with “right-sided His bundles,” the right bundle branch was a direct continuation. The clinical, electrophysiologic, and electrocardiographic implications of these anatomical observations are discussed.

ISSN:0009-7322    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

The precise mechanism of the vagus in opposing adrenergic influences on cardiac vulnerability has not been defined. In the present investigation, cholinergic stimulation was produced by administering the selective muscarinic agent methacholine (MCh) and ventricular vulnerability was assessed by measuring the repetitive extrasystole (RE) threshold. MCh produced a sustained 98 ± 12% (P< 0.0001) increase in the RE threshold; the increase was abolished by concurrent infusion of atropine (0.2 mg/kg). When MCh was administered during beta-adrenergic blockade with propranolol, however, no further increase in RE threshold occurred beyond that resulting from propranolol alone. Infusion of norepinephrine (NE), in a dose insufficient to provoke systemic hypertension, significantly lowered the vulnerable period threshold. This decrease was completely abolished by concurrent vagosympathetic stimulation (VS). It is concluded that VS affects ventricular vulnerability through its muscarinic action and that the protection against VF is in part due to modulation of neural and humoral betaadrenergic inputs.

ISSN:0009-7322    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

Four experienced coronary angiographers (two radiologists and two cardiologists) independently assessed the location and degree of coronary artery stenosis, and the location and degree of left ventricular wall motion abnormalities in 20 coronary angiograms. Marked interobserver variability was noted in quantifying percent coronary artery stenosis and degree of left ventricular wall motion abnormalities. For example, in only 13/20 (65%) of the coronary angiograms did all observers agree about the significance of a stenosis (defined as greater than 50% in diameter luminal narrowing) in the proximal or mid left anterior descending coronary artery. In 3/20 (15%) angiograms there was disagreement by at least one observer about the significance of lesions noted in the main left coronary artery.The ventricle was divided into five segments and the degree of wall motion abnormality graded into six categories of increasing severity from normal to dyskinesis. There was a 42% mean disagreement among all four observers where a disagreement between observers was defined as any difference in grading wall motion abnormalities.Interobserver variability reveals a significant limitation of coronary angiography.

ISSN:0009-7322    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

The comparative value of nitroglycerin (TNG), postextrasystolic potentiation (PESP) and their combination (TNG + PESP) to unmask asynergic residual contraction was examined, each patient serving as his own control. Twelve of 13 hypokinetic zones improved both with TNG and PESP. One remained unchanged with either. Of 15 akinetic zones, four improved with both TNG and PESP, while ten remained unchanged. One akinetic zone, although improved with TNG, remained unchanged with PESP. Four dyskinetic zones did not change with either. Six asynergic zones responding to TNG alone demonstrated further augmentation with TNG + PESP. However, none of 13 TNG unresponsive zones improved with TNG + PESP. Thus, TNG, PESP, and TNG + PESP are each equally capable of unmasking asynergic residual contractile ability.

ISSN:0009-7322    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

Small myocardial specimens were obtained from 12 patients undergoing coronary reconstructive surgery and from 12 patients undergoing surgical correction for cyanotic congenital heart defects. The specimens were analyzed for LDH isozyme distribution. A control analysis was performed on myocardial specimens obtained at the time of surgical correction for acyanotic congenital heart defects in seven patients with normal coronary arteries. There was a 42% increase in the proportion of A subunits in the hearts of coronary patients as compared to controls. This represented a shift toward an anaerobic isozyme distribution. There was no change in the percentage of A units from the hearts of cyanotic patients as compared to acyanotic hearts of the same age. Cardiac muscle from patients with coronary vascular disease had an altered LDH subunit composition. Such an alteration was not present with chronic systemic hypoxia. These deficiencies may or may not be related to differing local metabolic responses to the two conditions. However, in the clinical situations, ischemic heart muscle may be oxygen deprived to the point of lactic acid production while hypoxic heart muscle usually is not. Consequently, these findings may represent a compensatory cellular mechanism which provides for continued energy production during chronic ischemia by enhancing glycolysis.

ISSN:0009-7322    

出版商:OVID    

年代:1976

数据来源: OVID