ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTTo study the vasomotility of normal and diseased coronary arteries during dynamic exercise, symptom-limited supine bicycle exercise during cardiac catheterization was performed by 18 patients with classic angina pectoris. The cardiovascular response was assessed by hemodynamic measurements and computer-assisted determination of normal and stenotic coronary artery luminal areas from biplane coronary angiograms made before, during, and after exercise. After baseline measurements were recorded, 12 patients (group 1) performed bicycle exercise for 3.4 min (mean), reaching a maximum workload of 81 W (mean); at the end of exercise they received 1.6 mg sublingual nitroglycerin. After measurements at rest in six other patients (group 2), 0.1 mg intracoronary nitroglycerin was given, followed by exercise (3.8 min, 96 W; NS) and sublingual nitroglycerin as in group 1. During exercise in group 1, luminal area of the coronary stenosis decreased to 71 % of resting levels (p < .001), while area of the normal coronary artery increased to 123% of control (p < .001). After sublingual nitroglycerin at the end of exercise, area of the normal vessel further increased to 140% of control (p < .001), while luminal area of the stenosis dilated to 112% of resting levels (p < .001 vs exercise, NS vs rest). Pretreatment with intracoronary nitroglycerin increased both normal (121 %; p < .05) and stenotic (122%; p < .05) luminal areas, while preventing the previously observed narrowing of stenosis during exercise (114%; NS). Exercise resulted in a similar heart rate-systolic pressure product and caused angina pectoris in two-thirds of the patients in each group. However, patients pretreated with intracoronary nitroglycerin (group 2) had a lower mean pulmonary arterial pressure during maximum exercise (35 mm Hg) than those patients (group 1) not receiving pretreatment (47 mm Hg; p < .001). Group 2 patients reached a percentage of their predicted work capacity (65%) that was about the same as that during previous upright bicycle exercise (71 %; NS), while group 1 patients had a significantly lower work capacity (51% of predicted) than that before catheterization (82%; p < .001). Hence, narrowing of coronary artery stenosis during dynamic exercise is attributable to active vasoconstriction due to its reversibility by preexercise intracoronary nitroglycerin. Patients who did not experience narrowing of stenosis during exercise (group 2) had less evidence of myocardial ischemia (lower mean pulmonary arterial pressure) and maintained their work capacity. This indicates that vasoconstriction of coronary artery stenosis can be an important mechanism in causing myocardial ischemia during dynamic exercise in patients with classic angina pectoris.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTTo study the mechanism of disappearance of the physiologic third heart sound (S3) with advancing age, combined phonoechocardiographic and phonomechanocardiographic recordings from 165 normal subjects between 6 and 62 years old were quantitatively analyzed. Nearly all individuals under 40 years old had a recordable S3. Although recordable in 38.6% of the 44 subjects over 40 years old, the physiologic S3found in adults was less intense and occurred later in diastole when compared with that in children and adolescents. Marked changes in left ventricular filling hemodynamics were observed with aging, including an increase in left ventricular wall thickness and mass, a prolongation of the left ventricular isovolumetric relaxation period, a decrease in left ventricular early diastolic filling and wall thinning rates, and a reduction in the height and steepness of the rapid filling wave measured on the calibrated left apexcardiogram (linear correlation with age significant at p < .001 for all parameters). Although less pronounced, these changes were very similar to the diastolic abnormalities found in patients with pressure overload left ventricular hypertrophy. Therefore, the higher pressure load imposed on the left ventricular wall due to the well-known gradual increase in blood pressure that occurs during normal growth and adulthood appears to be the most likely explanation for the observed changes in diastolic filling. It is concluded that the later occurrence, the diminishing amplitude, and the eventual complete disappearance of the physiologic S3with age results from a decrease in early diastolic left ventricular filling and subsequent deceleration of inflow caused by the development of relative left ventricular hypertrophy in adulthood as compared with childhood.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTTo assess whether the site of myocardial infarction is an independent prognostic indicator, the outcome of patients with anterior myocardial infarction was compared with that of patients with inferior infarction. A consecutive series of patients who had suffered their first myocardial infarction was analyzed (398 with anterior and 391 with inferior infarction). Patients with anterior myocardial infarction had a higher 1 year mortality than those with inferior infarction (18.3% vs 10.5%, p = .002). When patients were matched for infarct size determined by peak creatine kinase (CK) level expressed as a multiple of the upper limit of normal, those with anterior myocardial infarction tended to have a higher 1 year mortality than those with inferior infarction for all subgroups of peak CK. Early mortality (day 1 to 28 after myocardial infarction) was greater in the anterior than in the inferior myocardial infarction group (10% vs 6.4%, p = .03); this was most significant when peak CK was greater than four times normal (12.4% vs 7.0%, p = .04). Late mortality was also higher in the anterior (8.4% vs 4. 1%, p = .04) than the inferior infarction group and this was most significant when peak CK was less than two times normal (15.2% vs 0%, p = .02) or greater than eight times normal (10.6% vs 4.1%, p = .04). Multivariate analysis with proportional-hazards regression confirmed the prognostic significance of location of infarction independent of peak CK level. Thus, infarct location was found to be a predictor of prognosis that is independent of infarct size based on peak CK levels.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTThe embryogenesis of tetralogy of Fallot is still much debated. In particular, the dextroposition of the aorta is not considered by all pathologists as a genuine abnormality in this congenital heart disease but rather as a false impression due to an exaggeration of the normal overriding caused by dilatation of the aorta secondary to abnormal hemodynamics. We used two-dimensional echocardiography to examine the spatial position of the aortic root in 22 patients with tetralogy of Fallot (aged 5 days to 24 years, mean 6.4 years) and in 23 normal subjects (aged 1 month to 27 years, mean 7.6 years). Using the parasternal short-axis view, we determined the percent rightward displacement of the aortic root in relation to the plane of the atrial septum, and the relationship between the aortic cusps and the atrial septum. We measured the value of the angle &thetas;, which was defined as the angle between the plane of the atrial septum and the plane of the left coronary-noncoronary commissure and leaflet appositional plane. In the control group, the aortic root was displaced to the right by only 23.6 ± 7.6%; the atrial septum crossed the posterior aspect of the aortic root at the middle (n = 19) or at the right half of the posterior cusp (n = 4), and the angle 0 had a value of 43.3 ± 8.8 degrees. In the 22 patients with tetralogy, the percent rightward shift of the aortic root was augmented to 55.5 ± 9% (p < .001) and the atrial septum was related to the posterior commissure in 14 patients, to the left coronary cusp in two patients, and to the left fourth of the posterior cusp in six patients; the angle 0 had a value of 9.2 11.2 degrees (p < .001). In the two groups, the position of the commissure between the right coronary and left coronary aortic cusps was similar in relation to a line passed forward from the atrial septum. We conclude that the aorta is truly dextroposed in tetralogy of Fallot, with a rightward shift due to a clockwise rotation of the aortic root (looking downstream), and that the axis of this rotation is the anterior aortic commissure. Our echocardiographic findings, which confirm conclusions of previous investigators based on pathologic anatomy, support the embryologic hypothesis of the lack of conal rotation in tetralogy of Fallot and permit a quantitation of the effects of this morphogenetic mechanism.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTTo determine objective predictors of survival, 53 patients with chronic, hemodynamically severe mitral regurgitation underwent rest and exercise radionuclide cineangiography, echocardiography, treadmill exercise testing, and ambulatory electrocardiographic monitoring before prospective (average 30 month) follow-up. At entry, symptom status correlated best with radionuclide-based right ventricular ejection fraction (RVEF) and left atrial size, while treadmill exercise tolerance correlated best with RVEF during exercise (r = .48, p < .005). Correspondingly, in 23 patients who underwent cardiac catheterization, pulmonary arterial systolic and wedge pressures were significantly inversely related to RVEF. On the 24 hr ambulatory electrocardiogram, nonsustained ventricular tachycardia was present in 29% of patients, most frequently when both RVEF and left ventricular ejection fraction (LVEF) were subnormal (p = .03 vs other patients). Since entry, 35 patients have been managed without surgery for 9 to 57 months (average 28); three of these who subsequently underwent operation also are among the 21 patients who have undergone mitral valve replacement (MVR). During the average 28 months of observation under medical treatment five of 35 nonoperated patients have died; all five were among the six nonoperated patients with RVEFs of 30% or less at entry, a descriptor that significantly identified those at high mortality risk (p < .0001 vs patients with RVEFs greater than 30%). All five also were among the eight nonoperated patients with LVEFs of 45% or less (lower limit of normal), a descriptor that also significantly predicted mortality. Three of the 21 patients who underwent surgery have died, all late after MVR. Among operated patients, only age was a predictor of postoperative survival. A trend toward improved survival was found in the patients with depressed right or left ventricular ejection fraction who underwent surgery compared with those who did not.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTPatients with heart failure have increased vascular resistance and evidence for increased neurohumoral drive. High levels of circulating norepinephrine are found in patients with heart failure, but it is not known whether they reflect increased sympathetic neural activity or result from altered synthesis, release, or metabolism of norepinephrine. We used microneurography (peroneal nerve) to directly record sympathetic nerve activity to muscle (mSNA) and also measured plasma norepinephrine levels in patients with heart failure and in normal control subjects. Our goal was to determine whether sympathetic nerve activity is increased in patients with heart failure and whether plasma norepinephrine levels correlate with levels of mSNA in heart failure. Resting muscle sympathetic nerve activity in 16 patients with moderate to severe heart failure (54 ± 5 bursts/min, mean ± SE) was significantly higher (p < .01) than the levels of activity in either nine age-matched normal control subjects (25 ± 4 bursts/min) or 19 "young" normal control subjects (24 ± 2 bursts/min). We found a significant correlation between plasma norepinephrine levels and mSNA (r = .73, p < .05). Neither mSNA nor plasma norepinephrine levels correlated with total systemic vascular resistance, cardiac index, leftventricular ejection fraction, or heart rate. However, both mSNA and plasma norepinephrine levels showed significant positive correlations (p < .05) with left ventricular filling pressures (r = .80, mSNA vs filling pressures; r = .82, norepinephrine levels vs filling pressures) and mean right atrial pressure. The results of the study provide the first direct evidence of increased central sympathetic nerve outflow in patients with heart failure and the first direct evidence that plasma norepinephrine levels show a reasonable correlation with sympathetic nerve activity to muscle in these patients. Furthermore, the data suggest that preload is an important determinant of SNA in these patients.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTAlthough the refractoriness of the human His-Purkinje system (HPS) during constantcycle length pacing appears to be closely related to the cycle length of the stimulation, the mode of adaptation of this refractoriness with sudden rate acceleration is not well understood. A systematic evaluation of this adaptation was performed in 14 patients with normal QRS durations and HV intervals referred for electrophysiologic evaluation. The relative refractory period of the HPS (HPS-RRP) was evaluated by the extrastimulus (S2) method during a constant ventricular drive (S1) having a cycle length as close to sinus rhythm as possible. An accelerated train of 6 ventricular beats (S1') was then added to the constant drive and the HPS-RRP of each successive beat of this train was similarly determined. Mean Sl'cycle length was 750 ± 164 msec (range 600 to 1000). Mean Sl'cycle length was 475 ± 55 msec (range 400 to 600). The HPS-RRP of each successive beat of the accelerated train was significantly shorter than that during the S1drive and behaved in a dampened oscillatory fashion alternating from a lower value on the odd-numbered beats to a higher value on the even-numbered beats. In contrast, the effective and relative refractory periods of the ventricular myocardium during the accelerated train behaved in a cumulative manner, decreasing progressively with the first 2 beats of the train before reaching a plateau value. In conclusion, the data reported here present a new and intriguing picture of the mode of adaptation of the HPS refractoriness to sudden rate acceleration. At least in the range of the cycle lengths used in this study, the refractoriness of the HPS behaves in a dampened oscillatory manner that is radically different from the behavior of the ventricular myocardial refractoriness.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTJunctional ectopic tachycardia has been described in infants but not in adults. Five adults with rapid symptomatic paroxysmal junctional tachycardia, distinct from the more common slower nonparoxysmal junctional tachycardia, were recently evaluated. The tachycardia was irregular (rate 120 to 250) and accompanied by periods of atrioventricular dissociation and narrow QRS complexes. A junctional origin was documented during electrophysiologic study in four of the five patients. Analysis of Holter recordings; the response to exercise, isoproterenol, and propranolol; and the effects of atrial and ventricular stimulation appeared to implicate abnormal automaticity of a high junctional focus that was catecholamine sensitive or dependent as the tachycardia mechanism. All patients responded somewhat to β-blockers, although a combination of procainamide and propranolol proved to be the most effective therapy in one patient and another chose electrode catheter ablation of the atrioventricular junction rather than continued drug therapy. Thus, junctional ectopic tachycardia may occur in adults and its mechanism appears to be related to abnormal automaticity that is catecholamine sensitive or dependent. Initial therapy should include β-blockers but selected patients may require more aggressive management.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID