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:

The initiation and termination of tachycardias were studied in five patients who suffered from recurrent attacks of ventricular tachycardia. In four, coronary artery disease with old myocardial infarction was present. A ventricular tachycardia could be initiated in all patients by a single right ventricular premature beat given during regular driving of the right ventricle. The tachycardia could be terminated by a single right ventricular premature beat, or two right ventricular premature beats given in close succession. In four of our patients an early right ventricular premature beat was followed by the next QRS complex of the tachycardia after an interval shorter than compensatory. Our results favor reentry as the causal mechanism for the tachycardias in our patients. Possible pathways for circus reentry leading to ventricular tachycardia can theoretically be composed of (1) the bundle branches, (2) Purkinje fibers with or without adjacent ventricular myocardium, (3) infarcted or fibrotic ventricular tissue, and (4) combinations of (1), (2), and (3).

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

This review deals with the functional anatomy of the six components of the mitral apparatus, namely, the left atrial wall, annulus, leaflets, chordae tendineae, papillary muscles, and left ventricular wall. Each component is considered individually, in the context of the apparatus as a whole, in relation to the mode of closure of the normal mitral valve, and in the light of many acquired and congenital disorders that disturb the harmony of the finely coordinated mitral mechanism and render it incompetent.The left atrium is related to mitral valve competence in terms of contraction and relaxation and in terms of dilatation of its posterior wall. The annulus not only serves as a fulcrum for the leaflets but exhibits sphincteric contraction in systole that decreases the size of the orifice. The two leaflets differ in shape but are nearly identical in area, and together are about two and one half times the area of the orifice that they are required to close. Leaflet abnormalities causing acquired or congenital mitral regurgitation result from deficient leaflet tissue, excessive leaflet tissue, or restricted leaflet mobility. Chordae tendineae are considered according to their leaflet attachments, ventricular attachments, thicknesses, lengths, and arborization patterns. Mitral regurgitation due to chordal abnormalities results from chordae that are abnormally long, abnormally short, ectopically inserted, or ruptured. In this context, systolic clicks and late systolic murmurs are discussed, and severeacutemitral regurgitation is contrasted with severechronicmitral regurgitation. The papillary muscles and the left ventricular wall represent the two muscular components of the mitral apparatus. An appraisal of papillary muscle dysfunction includes dysfunction with loss in continuity (rupture) and dysfunction without loss in continuity (fibrosis, ischemia, replacement). Finally, the role of altered left ventricular shape is discussed in the context of mitral regurgitation, and the effect of dilatation is ascribed chiefly to alterations in the position of papillary muscles and their directional axes of tension.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Sixty-two patients were investigated for chronic intravascular hemolysis from 3 months to 6½ years following aortic valve replacement; 27 patients had Starr-Edwards prostheses and 35 fascia lata grafts.The findings are suggestive of a significantly higher incidence and degree of hemolysis in patients with Starr-Edwards prostheses compared to those with fascia lata grafts. In both groups regurgitation was an important factor in producing hemolysis. In the absence of regurgitation fascia lata grafts do not produce significant hemolysis, while Starr-Edwards valves traumatize the red cells even in the absence of regurgitation. Starr-Edwards valves of small size are associated with hemolysis more often than larger ones are. Turbulent flow due to the obstructing ball is the probable mechanism of hemolysis in these patients. In most of the patients the degree of hemolysis appears to remain at the same level of activity. In rare instances, however, the hemolysis may regress. The mechanism for this is not clear. In a small number of patients, also, progressive hemolysis may necessitate removal and replacement of the valve.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Sixty-one critically ill infants with congenital heart disease had operative treatment within 6 weeks of birth. Anatomic and physiologic diagnoses were established preoperatively by cardiac catheterization and angiography in all. A variety of palliative or corrective operations was performed to relieve specific hemodynamic burdens. Thirty-seven (61%) survived hospitalization, but 18 had one or more postoperative complications. At the present time, 29 (48%) are alive 9-45 months after operation. Although operative mortality and morbidity rates are high, none of these patients was expected to survive early infancy without operation.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Systemic intraarterial blood pressure and heart rate have been measured during exercise on a foot ergometer in 13 patients suffering from unilateral intermittent claudication. Each limb was exercised separately for 5 min. Both systolic and diastolic blood pressure increased to significantly higher levels during exercise with the diseased limbs than during exercise with the nondiseased limbs. No significant difference was found in heart rate. After cessation of exercise the blood pressure and heart rate dropped abruptly. For the first 2 min of recovery the systolic blood pressure in the diseased limbs stayed higher than the pressure measured at rest immediately before exercise. Ten patients were also exercised for 2 or 3 min with arrested circulation. During this period no significant differences between the diseased and nondiseased limbs were found in relation to blood pressure or heart rate.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

This report documents five cases of supernormal (SN) conductivity in the sense of unexpected normalization of the previously existing bundle-branch block (BBB) and three cases of SN excitability in which impulses delivered to the ventricles propagated to the myocardium only during a well-defined interval in the cardiac cycles corresponding to the U waves of the preceding beat. In none of the patients could SN be abolished by atropine, suggesting absence of an important vagal role. In the five patients with SN conductivity there were three examples of right BBB in which spontaneous, as well as electrically induced premature atrial beats, were followed by normal QRS complexes only if they reached the right bundle during its SN phase. In the other two patients with bilateral BBB, strategically placed sinus P waves and electrically induced atrial impulses were conducted to the ventricles with normal P-His and His-Q intervals. Analysis of the electrocardiograms and His bundle electrograms indicated that SN conductivity resided in the bundle branches, and not in the A-V node. In one of two patients with bilateral BBB and SN conductivity in the right bundle branch, the SN-conducted beats occurred after both left and right ventricular escape beats, but were coupled to the preceding escape beats by longer intervals after left ventricular escape beats than after right ventricular escape beats. The difference was accounted for by the later activation of the right bundle branch when the preceding escape beat originated from the contralateral left ventricle. These observations favor an electrophysiologic explanation for the phenomenon of supernormality which is most probably related to the increased voltage of the transmembrane action potential in the period commonly known as the period of negative afterpotentials. This study provides no support for the hemodynamic or vagal theory of supernormality.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

From a compilation of 1411 gross dissections of the hearts from patients who had had recent electrocardiograms prior to death, 62 were found to have frontal QRS axes between +90 and +180°.Thirty-eight exhibited an S1Q3R3pattern-the second screening criterion basic to consideration for the label of left posterior hemiblock (LPH). Twenty-two of these also had right ventricular free wall weights in excess of 70 g. Two others exhibited inferior myocardial infarction only. Of the remaining 14, six afforded mild clinical suspicion of increased hemodynamic loading of the right heart but did not have increased right ventricular weights. Four had right bundle-branch block (RBBB), and only one had a prolonged P-R interval.The S1Q3R3pattern with right-axis deviation thus occurred in patients with or without right ventricular hypertrophy and with or without inferior wall myocardial infarction. Right bundle-branch block was a frequent occurrence in the spectrum of right-axis deviation (RAD) whether S1Q3R3was present or not.The scatter of the frequent associates of RAD-inferior myocardial lesions, right ventricular hypertrophy, a clinical history of right ventricular loading diseases, and RBBB—suggests three alternative ways of viewing the S1Q3R3pattern with RAD: (1) LPH isacause of S1Q3R3with RAD. It is a manifestation of left ventricular myocardial disease, but it may be a result of overt infarction, or may be mimicked by right ventricular disease. (2) LPH isthecause of S1Q3R3with RAD. It is the means by which diverse etiologies produce a distinctive electrocardiographic pattern (including left ventricular myocardial deficits, right ventricular enlargement, or a small group of unknown causes). (3) LPH is an artifact of convenience. Patients with RAD may or may not have S1Q3R3; they frequently have inferior wall myocardial infarction, right ventricular overload or enlargement, and RBBB.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

We have measured pulmonary artery (PA) and left ventricular diastolic pressures (LVDP) in patients with acute myocardial infarction to establish the relationships of PA pressure to LVDP. Paired determinations for the various parameters showed (mean difference in mm Hg): left ventricular end-diastolic pressure (LVEDP)-LVDP pre-a + 7.9,P< 0.001; LVEDP-mean PA wedge + 6.0,P< 0.001; mean PA wedge-LVDP pre-a, + 0.8,P> 0.2; PA end-diastolic pressure (PAEDP)-mean PA wedge (in all patients) +3.3,P< 0.001; PAEDP-mean PA wedge (patients with pulmonary vascular resistance ≦2 units) +1.3,P< 0.1; LVEDP-PAEDP +4.7,P< 0.001; and LVEDP-mean PA −2.0,P< 0.02. The relationship of LVEDP to mean PA wedge was: LVEDP (y) = 1.12 mean PA wedge (x) +4.69; Sy.x = 3.42; r = 0.92.After acute myocardial infarction, PA pressures did not accurately reflect LVEDP because atrial contraction made a large contribution to ventricular filling pressure. In addition, PAEDPs were not the same as mean PA wedge pressures because of some increase of pulmonary vascular resistance in many patients. Thus, PA pressures only provided reliable information about the level of pulmonary venous pressure. LVDP pre-a correlated well with mean PA wedge pressure, and therefore measurement of LVDP (pre-a and EDP) yielded information not only about pulmonary edema, but also about LV performance.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID