摘要:

To determine whether endurance exercise training can improve left ventricular systolic function in older men, 10 healthy sedentary men (64 ± 3 years old; mean ± SD) were studied. Training consisted of endurance exercise 4 ± 0.3 days per week for 11.8 ± 2.5 months at a progressively increasing intensity of 60–80% of maximal 02 uptake (Vo2max) with additional brief bouts of exercise equal to 93 ± 13% of Vo2max. Vo2max increased from 29.6 ± 4.1 to 37.2 ± 5.7 ml/kg/min (p< 0.001). Percent body fat was decreased (17.8 ± 3.6% versus 15.6 + 3.6%; p < 0.001). Before training, left ventricular ejection fraction, determined by electrocardiographic-gated equilibrium blood pool imaging, increased only modestly during exercise (from 66.3 ± 6.7% at rest to 70.6 + 6.9% at peak exercise). After training, the increase in ejection fraction during exercise was significantly greater (from 67 ± 4.8% at rest to 77.6 ± 7.5% at peak exercise) than that observed before training and was similar to that in young sedentary men (64 ± 7% at rest versus 74 + 9%So at peak exercise). Although the changes in systolic pressure from rest to exercise were similar, end-systolic volume decreased significantly at peak exercise after (51 ± t12 versus 38 ± + 13 ml; p < 0.005) but not before (46 ± 8 versus 43 + 13 ml; p=NS) training with a shift in the end-systolic volume-systolic blood pressure relation to the left compatible with enhanced inotropic state. Exercise training induced proportional increases in left ventricular enddiastolic diameter and posterior wall thickness, measured echocardiographically, with no change in the wall thickness-to-radius ratio (0.27 ± + 0.04 versus 0.28 ± + 0.03), suggestive of volume-overload hypertrophy. End-diastolic volume at rest was increased (138 ± 11 versus 155 ± 26 ml;p< 0.05). Stroke volume was significantly greater at peak exercise in response to training (110 ± t17 ml before versus 132 ± 27 ml after training;p< 0.05). The differences in end-diastolic volume and stroke volume at peak exercise between the trained and untrained states correlated strongly (r= 0.95). At a given increase in end-diastolic volume during exercise, the increase in stroke volume was more after than before training. Furthermore, at a given change in end-systolic volume from rest to exercise, the subjects attained a higher systolic blood pressure after than before training. These data suggest that endurance exercise training of sufflicient intensity can improve left ventricular systolic performance in older men.

ISSN:0009-7322    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

To map globalepicardialrepolarizationpatternsandtestthe “SI” modelofTwave generation, the patterns of epicardial activation and repolarization in patients with chronic pulmonary thromboembolism and right ventricular hypertrophy were studied by computerized mapping techniques and monophasic action potential (MAP) recordings. The ventricular activation patterns were characterizedbydelayed rightventricularactivation and the absenceofnormal early epicardial ventricular breakthrough in some cases. The repolarization patterns were characterized bynonuniform distribution ofTwave morphologies. The Twaves were predominantly positive over the left ventricular epicardium and negative or biphasic over the right ventricularepicardium. Theactivation-recovery (A-R) intervalswere measured from thelocal activation tothemaximal dV/dtoftheupstroke ofthe Twaves (Wyattmethod).Thedifference betweentheA-RintervalsandtheMAPfromonsetofactivationto90%repolarization (MAP90) varies accordingtoTwave morphologyandcould be as highas 96 msec with positiveTwaves, despite significant correlations (r= 0.56–0.90) between MAP90and A-R intervals for each morphology. BetteroverallcorrelationswerefoundiftheminimaldV/dton thedownslopeofthe positive Twaves was chosen to estimate the time oflocal repolarization (alternative method). Using this method, the mean A-R intervals were the same over the right and left ventricles. Cardiopulmonary bypass significantly prolonged the action potential duration equally at all parts ofthe epicardium. We conclude that in patients with rightventricular hypertrophy, the timeoflocalrepolarization can bestbeestimatedbyour alternativemethod;therightventricle completes activation and repolarization laterthan the leftventricle, and the distribution ofT wave morphologies is nonuniform, with predominantly positive Twaves observed over the left ventricleandnegativeor biphasicTwaves observedover therightventricle. Thesefindings are compatiblewith the SI model ofthe generation ofTwaves.

ISSN:0009-7322    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Oral flecainide acetate was administered to 34 patients with documented symptomatic paroxysmal supraventricular tachycardia (PSVT) with a double-blind, placebo-controlled, 8-week crossover trial design. PSVT was defined as a regular tachycardia of at least 120 beats/min without evidence ofatrioventricular dissociation. The study required considerable patientcooperation. Patientsfirstentereda 4-weekqualifyingphasefollowedbya3-week, open label, flecainide dose-rangingphase. Theywere then randomized in a blindfashionto receive eitherplaceboortoleratedflecainidedoseforan 8-weektreatmentperiodandthencrossedover afterfoursymptomaticdocumentedepisodesofPSVTor attheendofthetreatmentperiod. By allefficacyparameters analyzed, flecainidewas superiortoplacebo. Flecainidewas associated with an actuarial 79% freedom from symptomatic PSVT events compared with only 15% on placeboat60days (p< 0.001). Ofthe34patients, 29had recurrence ofsymptomatic PSVTat leastonce duringtheplacebophase;onlyeightpatientshada recurrence duringtheflecainide phase (p< 0.001). The median time to the first symptomatic PSVT event was 11 days in the placebo group and greater than 55 days in the flecainide group (p< 0.001). Likewise, the intervalbetweenattackswas a medianof12dayson placebocomparedwithmore than55days on flecainide (p< 0.001). Finally, the fiecainide slowed symptomatic PSVT heart rates to 143 ± 12 beats/minfrom 178 ± 12 on placebo (p< 0.02) in the seven patientswho hadevents in theplacebo and flecainide treatment phases. In summary, flecainide significantlyreduces the likelihoodofsymptomaticPSVTrecurrences, andit, therefore, isan effectiveagentinpatients who have symptomatic PSVT.

ISSN:0009-7322    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Thrombolytic therapy has been shown to improve clinical outcome when administered early aftertheonsetofsymptomsofacutemyocardialinfarction;themechanismofbenefitisbelieved to be reestablishment and maintenance ofcoronaryartery patency. Anistreplase is a second generationthrombolyticagentthatiseasilyadministered andhas alongdurationofaction. To compareanistreplase (30units/2-5min)andtherapywiththeFoodandDrugAdministration-approved regimen ofintravenous streptokinase (1.5 million units/60 mmn), a randomized, double-blind, multicenterpatencytrialwasundertakenin370patientslessthan76yearsofage withelectrocardiographic STsegmentelevationwhocouldbetreatedwithin4hoursofsymptom onset. Coronarypatencywasdeterminedbyreading, inablindedfashion, angiograms obtained early (90–240 minutes; mean, 140 minutes) and later (18–48 hours; mean, 28 hours) after beginning therapy. Early total patency (defined as Thrombolysis in Myocardial Infarction grade 2 or 3 perfusion) was high after both anistreplase (132/183=72%) and streptokinase (129/176=73%) therapy, and overall patency patterns were similar, although patent arteries showed “complete” (grade3) perfusion moreoftenafteranistreplase (83%) than streptokinase (72%) (p= 0.03). Similarly, residualcoronarystenosis, determinedquantitativelybyavalidated computer-assisted method, was slightly less in patent arteries early after anistreplase (mean stenosis diameter, 74.0%) than streptokinase (77.2%,p= 0.02). In patientswith patent arteries withoutotherearlyinterventions, reocclusionriskwithin1-2dayswasdefinedangiographically andfoundtobeverylow (anistreplase=1/96, streptokinase=2/94). Averagecoronaryperfusion gradewasgreater, andpercentresidualstenosiswasless, atfollow-upthanoninitialevaluation anddidnotdifferbetweentreatmentgroups. Enzymaticandelectrocardiographicevolutionwas not significantly different in the two groups. Despite rapid injection, anistreplase was associated with only a small (4–5 mmHg), transient (at 5–10 minutes) mean differential fall in bloodpressure. In-hospital mortalityrates were comparable foranistreplase and streptoki-nase (5.91%, 7.1%). Stroke occurred in one (0.5%) and three (1.6%) patients, respectively; one stroke was hemorrhagic. Other serious bleeding events and adverse experiences occurred uncommonlyandwithsimilarfrequencyinthetwogroups. Thus, fortheendpointsofourstudy (patency, safety), anistreplase and streptokinase showed overall favorable and relatively comparable outcomes, with a few differences. When given to patients within 4 hours from onsetofsymptoms ofacutemyocardialinfarction, boththrombolytic agents established high and similar total patency rates within a mean of 2.4 hours after therapy, although quantitative residual stenosis was slightly less early after anistreplase. The clinical importance ofthese orother differences, such as ease ofdrugadministration, are uncertain but will be answered by ongoing comparative mortality studies and by broader clinical experience. In the interim, these data support the continued use ofboth ofthese agents in acute myocardial infarction.

ISSN:0009-7322    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

In 167 patients with complete occlusion (> 3 cm) of the femoropopliteal artery, percutaneous transluminal laser angioplasty (PTLA) was performed after an unsuccessful attempt at crossing with a guide wire and was immediately followed by balloon dilatation. An Nd-YAG laser and an optical fiber delivery system with a sapphire tip serving as a contact probe were used for PTLA. In 132 of 167 (79%) patients, the occluded segment was successfully reopened. Clinical symptoms improved in 126 of 167 (75%) patients. PTLA was unsuccessful in 35 patients, and in 15 of these, injury of the vessel wall occurred. In one patient, surgical drainage of a large hematoma became necessary. All patients in whom recanalization had been achieved were randomized to receive long-term treatment with either phenprocumarol or acetylsalicylic acid (ASA) plus dipyridamole to prevent rethrombosis. At 36 months of follow-up, the cumulative patency rate (CPR) was 63%. A complete reobstruction in 32 patients (24%) and a partial reobstruction in 15 patients (11%) were found angiographically. The CPR after 36 months was significantly lower (p< 0.05) in patients younger than 60 years of age (54%) than in patients older than 60 (68%); it was also significantly lower (p< 0.05) in patients with reduced peripheral runoff (55%) due to obstructed arteries of the lower leg than in patients with unaffected runoff (73%). The CPR was 65% in recanalized segments shorter than 7 cm and was 62% in recanalized segments longer than 7 cm. In patients treated with ASA plus dipyridamole, the CPR was 60%, and in patients who underwent anticoagulation therapy, the CPR was 65% (NS). The CPR was also significantly lower (p< 0.05) in patients who were still smoking during follow-up (62%) than in patients who never smoked or quit smoking (77%). These results suggest that PTLA combined with balloon dilatation is beneficial for the management of patients with chronic peripheral arterial occlusion and provides good long-term patency rates.

ISSN:0009-7322    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Stenting of native coronary arteries with a balloon-expandable stent was attempted in 226 patients after elective angioplasty. Delivery of the device was successful in 213 (94%) of the patients. Of these, 39 received aspirin and dipyridamole only (group 1) and 174 received aspirin, dipyridamole, and warfarin for 1–3 months (group 2). There was no abrupt closure (c1 day) or perioperative death in either group. In-hospital or perioperative complications in group 1 compared with group 2 were as follows: subacute closure (1—14 days), seven (18%) patients versus one (0.6%) patient, respectively, p < 0.0001; myocardial infarction, five (13%) patients versus one (0.6%) patient, respectively; condition requiring urgent bypass surgery, one (2.5%) patient versus no patients, respectively. Thus, the incidence of major complications such as death, myocardial infarction, or a condition requiring urgent bypass surgery was 15% in group 1 and 0.6% in group 2. Clinical follow-up revealed that 92% of the patients were asymptomatic at 3 months after stenting compared with 6% before stenting (p< 0.0001). Of the 13 patients who were symptomatic, nine underwent cardiac catheterization and, ultimately, successful elective coronary angioplasty or bypass surgery. We conclude that a high delivery success rate can be expected with this device and that clinical thrombosis is less frequent in anticoagulated patients than in nonanticoagulated patients. Furthermore, in this selected patient population, coronary stenting results in a low incidence of in-hospital and perioperative complications. Clinical success, defined by absence of symptoms, appears to be sustained at 3 months.

ISSN:0009-7322    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

To determine whether patients at risk for paroxysmal atrial fibrillation could be detected while in sinus rhythm, the signal-averaged electrocardiogram triggered by P waves was recorded in 42 patients with paroxysmal atrial fibrillation (Paf group) and in 50 control patients. The root mean square voltages (LP10, LP20, and LP30) for the last 10, 20, and 30 msec and the duration (Ad) of filtered (40—300 Hz) P wave of the spatial magnitude were measured. LP10and LP20were significantly lower in the Paf than in the control group (LP10, 1.92 ± 0.58 versus 2.49 ± 0.78, μV,p< 0.001; LP20, 2.47 ± 0.78 versus 3.46 ± 1.20, μV, p < 0.0001), although no significant difference in LP30was found between groups. Ad was also significantly longer in the Paf than in the control group (137.0 ± 14.3 versus 118.6 ± 11.3 msec,p< 0.001). These differences between the Paf and control groups remained significant even after dividing by the presence or absence of organic heart diseases. The criteria of “LP20=3.5, μV or less” and “Ad > 120 msec” as defining “atrial late potential” gave a sensitivity of 91% and a specificity of 76%. These findings suggest that patients at risk for paroxysmal atrial fibrillation could be detected while in sinus rhythm by using the P wave-triggered signal-averaged electrocardiogram.

ISSN:0009-7322    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

To determine whether there are differences in responses to thrombolytic therapy in certain populations, the data for the Thrombolysis and Angioplasty in Myocardial Infarction (phase 1) study were analyzed for black and white patients. Baseline variables including risk factors and extent of coronary artery disease were similar in the 352 white and 24 black patients. The time from onset of chest pain to recombinant tissue-type plasminogen activator (rt-PA) therapy and rt-PA dosing regimens were the same in the two groups. The patency rate of the infarct-related artery at 90 minutes was 91% for blacks and was 72% for whites (p= 0.051). Blacks displayed significantly lower nadir fibrinogen levels (0.57 ± 0.62 versus 1.3 ± 0.76 g/l,p< 0.0001), greater δ fibrinogen (baseline–nadir) (2.7 ± 1.1 versus 1.7 ± 1.1 g/l,p< 0.0001), and increased peak levels of fibrin(ogen) degradation products (837 ± 865 versus 245 ± 475, μg/ml,p< 0.0001). rt-PA antigen levels tended to be higher in blacks than in whites (2.8 ± 2.2 versus 2.2 ± 3.2 μg/ml [p= 0.10] at the peakand 1.6 ± 1.3 versus 0.99 ± 1.4, g/ml [p= 0.06] at the end of the maintenance infusion). Major clinical outcomes including survival until time of hospital discharge (92% black versus 93% white,p=0.68) were not significantly different. However, despite undergoing fewer angioplasty procedures (25% versus 46.3%,p= O0.047), blacks received more transfusions (58.8% versus 19.5% were administered ⩾ 2 units packed erythrocytes,p= 0.001). In conclusion, black patients have an apparent enhanced sensitivity to rt-PA, which is manifested by increased thrombolytic efficacy, a more pronounced systemic fibrinogen breakdown, and increased transfusions.

ISSN:0009-7322    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

The purpose of this study was to examine high density lipoprotein cholesterol (HDL-C) levels in a sample of community-living women and men who consumed 1 drink of alcohol/day or less. Self-reports of alcohol consumption and clinical assessments of plasma lipid and lipoprotein levels were obtained twice, at 12 months apart. Among men, consumption of 1 drink/day or less was unrelated to levels in HDL-C. In contrast, among women alcohol consumption throughout this relatively low consumption range was positively associated with HDL-C levels. These findings indicate that the association of alcohol and higher levels of HDL-C may occur at lower intakes of alcohol in women than in men.

ISSN:0009-7322    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

To investigate the ventricular expression of atrial natriuretic peptide (ANP) in human hypertrophic hearts, we conducted an immunohistochemical study of 130 endomyocardial biopsy specimens obtained from the right side of the ventricular septum (RVB), left ventricular free wall (LVB), or both from a total of 80 patients: 44 patients with hypertrophic cardiomyopathy (HCM), 14 with apical hypertrophic cardiomyopathy (APH), 13 with hypertensive hearts (HHD), and nine without hypertrophy (controls). No patients had apparent congestive heart failure. ANP was not seen in ventricular myocytes in controls but was identified in biopsy specimens of hypertrophic hearts, and its distribution was characteristic in each hypertrophic group: 15 RVB (37%) and two LVB (7%) of the HCM group, one RVB (7%) and two LVB (18%) of the APH group, and zero RVB (0%/) and five LVB (46%) of the HHD group. Clinical data (including echocardiographic, hemodynamic, and angiographic data) were not directly related to ventricular ANP expression in HCM, APH, or HHD with one exception. In HHD patients, LVB specimens with ANP showed greater ventricular wall thickness than LVB specimens without ANP. According to histological data, however, the ANP-present RVB specimens of HCM or ANP-present LVB specimens of HHD had greater myocyte size than did the ANP-absent specimens. In addition, in HCM patients, the ANP-present RVB specimens showed more severe fibrosis and myofiber disarray than did the ANP-absent specimens. We conclude that a failing state and hemodynamic overload are not likely to be indispensable for ANP expression in human hypertrophic ventricles and that ventricular ANP expression occurs as a response to disease-specific changes: hemodynamic overload in HHD and histological changes such as myocardial fiber disarray, hypertrophy of myocytes, and fibrosis in HCM, which may reflect the characteristic distribution of intraventricular ANP.

ISSN:0009-7322    

出版商:OVID    

年代:1991

数据来源: OVID