ISSN:0009-7322    

出版商:OVID    

年代:1968

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1968

数据来源: OVID

摘要:

Certain temporal patterns of A-V and V-A transmission in experimental preparations resemble phenomena attributed to "supernormal" conduction in the clinic. Detailed study of the properties of the A-V transmission system in such experiments reveals alternative explanations in which supernormality is clearly eliminated. By application of similar principles, supernormality can be eliminated as a factor in most if not all of the published examples. Three major categories can be discerned: (1) occult 2:1 A-V block, in which an idioventricular beat "retracts" an otherwise refractory barrier within the A-V node; (2) alternation between dissociated intranodal transmission pathways; and (3) "ventriculophasic" (vagal) depression of nodal conductivity.

ISSN:0009-7322    

出版商:OVID    

年代:1968

数据来源: OVID

摘要:

The electron microscopic structure of heart muscle and the ultrastructural basis of cardiac contraction have been reviewed. The relation between muscle length and developed tension has been explained in terms of the structure of the sarcomere, which is the basic unit of contraction. Using the derived length-tension curve of the sarcomere, developed tension has been attributed to the overlap of thick and thin filaments within the sarcomere, lending support to the "sliding" mechanism in heart muscle.It has been shown that initial sarcomere length is a function of ventricular filling pressure and that this relation explains the normal limits of the heart as a pump, including: (1) the Starling mechanism whereby increased diastolic volume (EDV) engenders an increased stroke volume (SV), (2) the upper limits to ventricular filling pressure and volume, and (3) the normal range to the ventricular ejection fraction (SV/EDV). Further, ultrastructure helps to define the processes which occur with acute and chronic ventricular dilatation. In this regard, the importance of sarcomere dispersion and "fiber slippage," which may lead to disordered ventricular function, have been discussed.

ISSN:0009-7322    

出版商:OVID    

年代:1968

数据来源: OVID

摘要:

All of our cases of abnormal pulmonary venous connections collected to the middle of 1965 and verified at surgery or autopsy have been reviewed by means of diagrams and tabulations, using a specially devised code to facilitate the survey. The material consisted of 52 autopsy cases (half of them obtained after surgery) and the cases of 72 patients who survived operation. The postmortem group was much younger than the surgical group and differed also from the latter by showing male preponderance as well as relatively many instances of total abnormal pulmonary venous connection and frequently associated cardiac anomalies.Partial anomalous connection of right pulmonary veins was 10 times more frequent than that of the left pulmonary veins. This was caused by (1) the frequent drainage of some of the right pulmonary veins into the junctional area between right atrium and superior vena cava in the presence of normal left pulmonary veins, and (2) the complete absence of isolated left pulmonary venous connection to the right atrium. Abnormal connection of solitary pulmonary veins was always effected to the most proximal venous structure among the four possible ones which are derived from the main embryonic channels (superior vena cava and inferior vena cava on the right side, and left superior vena cava and coronary sinus on the left side). Common pulmonary veins from one lung also drained in accordance with this proximity rule, if this may be taken to apply also to the drainage of right pulmonary veins into the right atrium. The one exception in our material was the drainage of all right pulmonary veins into the portal venous system. Total abnormal pulmonary venous connection may be found with all structures mentioned, but most frequently with the left superior vena cava, or coronary sinus, or both, usually by way of a common pulmonary vein. In a few cases however, drainage into different sites, all of them abnormal, did occur. Then again the proximity rule seemed to apply.A tentative embryological explanation is given for the patterns described.

ISSN:0009-7322    

出版商:OVID    

年代:1968

数据来源: OVID

摘要:

In an infant with type A Wolff-Parkinson-White syndrome, atrial reciprocal beats and attacks of reciprocating tachycardia were repeatedly recorded. Their dependence on a prolongation of the P-R interval could be well demonstrated during Wenckebach periods. Because of the normal aspect of the QRS complex during arrhythmia, the short ventriculo-atrial conduction time (0.08 sec), and the vectorial orientation of the secondary P wave, it was concluded that retrograde reactivation of the atria probably took place via the anomalous bundle. The versatility of the conduction through the accessory bundle is shown by the fact that its direction may change from antegrade in one beat to retrograde in the next. The importance of a circus movement in the genesis of some types of tachycardia in the WPW syndrome is discussed.

ISSN:0009-7322    

出版商:OVID    

年代:1968

数据来源: OVID

摘要:

Disturbances in atrial conduction or rhythm, or both, were found in 16 of 27 patients undergoing the surgical creation of an atrial septal defect by the Blalock-Hanlon technique. These included P-wave aberrations of intra-atrial block and ectopic atrial rhythm, A-V rhythm, A-V dissociation, sinus bradycardia, atrial flutter, escapecapture bigeminy, and atrial premature beats. Some of these were transient and occurred within 2 weeks after surgery. It seems likely that tissue trauma engendered by the clamp and resection of the atrial septum with possible injury to the internodal conducting pathways may be the genesis of these early postoperative disturbances. Of the eight cases with transient disturbances, six occurred in this period.Later changes, such as intra-atrial block, sinus bradycardia, and atrial flutter, may be atttributed to changes in atrial size secondary to the postoperative pathophysiology. Digitalis intoxication and congestive heart failure cannot be excluded as contributory factors in either the early or the late disturbances.It was not possible to correlate the incidence and nature of these disturbances with morbidity and mortality. In such severely ill, cyanotic infants, irregularities, however slight, may have altered cardiac function significantly and contributed to their deaths.

ISSN:0009-7322    

出版商:OVID    

年代:1968

数据来源: OVID

摘要:

Proper placement of pacemaker catheters can be facilitated by recording endocardial electrograms from the catheters. These electrograms are also helpful in the investigation of pacemaker failure. Endocardial contact is indicated by S-T segment elevation. When bipolar catheters are used, these "contact currents" may be visible in electrograms from the tip or ring electrodes, or both.Right ventricular cavity electrograms are characterized by their high voltage and are influenced by intraventricular conduction defects and acute myocardial infarction. Serial changes have been described indicating myocardial injury, infarction, and healing in the area underlying the catheter tip.

ISSN:0009-7322    

出版商:OVID    

年代:1968

数据来源: OVID

摘要:

Fatty infiltration causing changes in the silastic poppet of the Model 1000 series Starr-Edwards aortic valve prostheses (ball variance) has been detected with increasing frequency and can result in sudden death. Phonocardiograms were recorded on 12 patients with ball variance confirmed by operation and of 31 controls. Ten of the 12 patients with ball variance were distinguished from the controls by an aortic opening sound (AO) less than half as intense as the aortic closure sound (AC) at the second right intercostal space (AO/AC ratio less than 0.5). Both AO and AC were decreased in two patients with ball variance, with the loss of the characteristic high frequency and amplitude of these sounds. The only patient having a diminished AO/AC ratio (0.42) without ball variance at reoperation had a clot extending over the aortic valve struts. The phonocardiographic findings have been the most reliable objective evidence of ball variance in patients with Starr-Edwards aortic prosthesis of the Model 1000 series.

ISSN:0009-7322    

出版商:OVID    

年代:1968

数据来源: OVID

摘要:

Eleven patients aged 8 to 15 years underwent measured asymmetrical annuloplasty for severe mitral regurgitation in the years 1961 through 1966. They had had a total of 20 attacks of acute rheumatic fever. The intervals between the last attack of acute rheumatic fever and operation ranged from 2 to 8 years. The criteria for surgery were congestive failure and progressive cardiac enlargement. Using the hydraulic formula of Gorlin, a mitral annuloplasty was tailored to the size of each patient so that insufficiency was eliminated without producing hemodynamically significant stenosis.In this group of 11 children there has been one death. The majority of our 11 patients reacquired murmurs of mitral regurgitation. Satisfactory results, however, are not dependent on complete hemodynamic correction. All patients have improved remarkably and have sustained this improvement up to 7 years. These results suggest that mitral annuloplasty should be the operation of choice in children with severe mitral regurgitation.

ISSN:0009-7322    

出版商:OVID    

年代:1968

数据来源: OVID