摘要:

BackgroundThe disease gene for hypertrophic cardiomyopathy (HCM) has been identified as the β-myosin heavy chain (β-MHC) gene in some HCM families. We describe extensive clinical evaluations in two kindreds with two distinct point mutations in the β-MHC gene.Methods and ResultWe used single-strand confirmation polymorphism (SSCP) gel analysis of polymerase chain reaction-amplified products capturing each of the 40 β-MHC gene exons to identify distinct missense mutations in two HCM kindreds. Clinical, ECG, and echocardiographic studies were performed in the two kindreds: kindred 2755 with amino acid 908Leu→Valmutation and kindred 2002 with amino acid 403Arg→Glnmutation. The morphological appearances of HCM were similar in these two kindreds. However, the two kindreds differed with respect to disease penetrance, age of onset of disease, and incidence of premature sudden death. Twelve of 31 adults (≥ 17 years) with the disease gene in kindred 2755 did not have left ventricular hypertrophy (LVH), and only five of these had ECG abnormalities. Thus, the disease penetrance in adults with this mutation was only 61%. None of 11 children aged < 16 years had LVH. The 908 mutation was associated with a low incidence of cardiac events: Only two sudden deaths and one syncope occurred in 46 individuals with the mutant allele. In contrast, LVH was present in all 11 adults in kindred 2002 with the 403 mutation (100% disease penetrance). In addition, three of four affected children were symptomatic and had clinical evidence of HCM. The disease in this kindred was severe and resulted in six premature sudden deaths. Seven additional patients had syncope or presyncope.ConclusionsIn some kindreds, the HCM disease gene is more prevalent than indicated by echocardiography and ECG. Some point mutations may be associated with a more malignant prognosis. Preclinical identification of children with mutations associated with a high incidence of sudden death and syncope provides the opportunity to evaluate efficacy of early therapeutic interventions.

ISSN:0009-7322    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

BackgroundSecondary involvement of the mitral–aortic intervalvular fibrosa and the anterior mitral leaflet (subaortic structures) can occur in patients with aortic valve endocarditis. The secondary involvement of these structures occurs as a result of direct extension of the infection from the aortic valve or as a result of an infected aortic regurgitant jet striking the ventricular surfaces of the mitral–aortic intervalvular fibrosa and the anterior mitral leaflet. The abscess of mitral–aortic intervalvular fibrosa can expand to form an aneurysm. Subsequently, this mitral–aortic intervalvular fibrosa aneurysm can develop a perforation and communicate with the left atrium, resulting in the systolic regurgitation of blood from the left ventricular outflow tract into the left atrium. Secondary infection can also occur on the ventricular surface of the anterior mitral leaflet and result in the formation of an aneurysm or perforation of anterior mitral leaflet.Methods and ResultsThis study examines the utility of transesophageal echocardiography in the detection of these subaortic complications in 55 consecutive patients with aortic valve endocarditis. A total of 24 patients (44%) had involvement of subaortic structures, including four with an abscess in the mitral–aortic intervalvular fibrosa, four with mitral–aortic intervalvular fibrosa aneurysm, seven with perforation of the mitral–aortic intervalvular fibrosa with communication into the left atrium, two with an aneurysm of the anterior mitral leaflet, and seven with perforation of the anterior mitral leaflet. The transesophageal echocardiographic findings were confirmed at surgery in 20 patients and at necropsy in two. By comparison, transthoracic echocardiography visualized these lesions in five of 24 patients (21%), including none of four with mitral–aortic intervalvular fibrosa abscesses, two of four with mitral–aortic intervalvular fibrosa aneurysms, one of seven with mitral–aortic intervalvular fibrosa perforations, one of two with anterior mitral leaflet aneurysms, and one of seven anterior mitral leaflet perforations. Eccentric mitral regurgitation-type systolic jets were noted in eight additional patients by transthoracic color flow imaging, and this finding suggested the possibility of these unusual subaortic complications. If these patients are included, then transthoracic echocardiography suggested the presence of these subaortic complications in 13 of 24 patients (54%).ConclusionsThe results indicate that 1) involvement of the subaortic structures in patients with aortic valve endocarditis may be more common than previously recognized, 2) patients with aortic valve endocarditis and eccentric jets of mitral regurgitation on transthoracic echocardiography should undergo further evaluation by transesophageal echocardiography to exclude these unusual complications, 3) precise recognition of these complications is of value in the optimal medical and surgical management of these patients, and 4) these complications maybe responsible for unexplained congestive heart failure and hemodynamic deterioration in some patients with aortic valve endocarditis.

ISSN:0009-7322    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

BackgroundThird-generation implantable cardioverter-defibrillators are devices designed to treat ventricular tachycardia (VT) and ventricular fibrillation (VF) by means of overdrive pacing, cardioversion, or defibrillation. So far, the efficacy of tiered therapy has been documented only in small series. Therefore, a European multicenter clinical evaluation study of a new tachyarrhythmia control device, the Medtronic PCD pacer-cardioverter-defibrillator with epicardial patch-lead configuration, was undertaken.Methods and ResultsWe report on 102 patients (mean age, 55±13 years) from 11 European centers. PCD devices implanted between May 1989 and February 1991 were included. The patients suffered from hemodynamically significant ventricular tachyarrhythmias not suppressed by antiarrhythmic drug therapy and unrelated to acute myocardial infarction; one patient had nonsustained VT and severely depressed left ventricular function. Seventy patients had coronary artery disease with old myocardial infarctions, 23 had cardiomyopathies of various etiologies, and nine patients had no detectable heart disease. Mean ejection fraction was 36±14% (range, 10–76%). Mean intraoperative defibrillation threshold (51 patients) was 10.6±5.1 J (range, 2–18 J). The documented follow-up ranged from 1 to 21 months (mean, 9.4±5.8 months), or 79.9 cumulative patient-years. Perioperative mortality was 3.9%1. The actuarial survival rate at 12 months was 91%. One sudden arrhythmic death occunred. Sixty patients (58%) received device therapy. Seventeen patients had therapies only for “VF” episodes, 16 patients only for VT, and 28 patients for VT and “VF” episodes. Based on device memory data, 1,235 spontaneous VT episodes were detected and treated in 43 patients. Twelve hundred four of these VT episodes received painless initial antitachycardia pacing therapy, restoring sinus rhythm in 91%. The 108 ongoing episodes received 209 multiple therapeutic attempts. Eighty-five additional overdrive pacing therapies restored sinus rhythm in 301%. Initial ineffective antitachycardia pacing therapies received 51 cardioversion pulses. The success rate was 61%. Seventy-three additional cardioversion pulses were delivered to backup ineffective pacing therapy as well as ineffective secondary cardioversion pulses. Their success rate was only 40%o. Two hundred eighty-six spontaneous episodes were detected in 44 patients as “VF.” Overall defibrillation efficacy was 97.6%.ConclusionsThe implanted device nearly eliminates sudden arrhythmic death in patients with documented, potentially fatal ventricular tachyarrhythmias. Automatic tiered therapy is highly effective to restore sinus rhythm, provided that an integrated two-zone tachycardia detection algorithm is used, assigning lower tachycardia rates to overdrive pacing and/or cardioversion and higher tachycardia rates to defibrillation. In general, spontaneous VTs can be terminated by automatic overdrive pacing, and painful or disturbing countershock therapies are not required to terminate the majority of spontaneous VT episodes.

ISSN:0009-7322    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

BackgroundAtrial fibrillation is usually thought of as a “random” pattern of circulating wavelets. However, local atrial activation should be influenced by the constant anatomy and receding tail of refractoriness from the previous activation. The general tendency for wave fronts to follow paths of previous excitation has been termed “linking.” We examined intra-atrial electrograms recorded during atrial fibrillation for evidence of linking.Methods and ResultsTwo minutes of atrial fibrillation were recorded in 15 patients with an orthogonal catheter. We have previously demonstrated that this catheter can be used to detect changes in the direction of local atrial activation. A mean vector was calculated for each electrogram. The similarity of the direction of the vectors from two consecutive electrograms can be quantified on a scale of 1 to −1 by calculating the cosine (cos) of the smallest angle (&thetas;) between them. Two vectors pointing in the same or opposite directions then have cos(&thetas;) = 1 or −1, respectively. For the entire group of patients, mean cos(&thetas;) was significantly greater than 0 (mean, 0.36;p< 0.001). In nine of 15 patients, there were groups of six or more consecutive beats (total, 44 groups; range, six to 14 beats per group) in which the direction of activation of each beat was within 30° of the previous beat. The likelihood of one group of six or 14 consecutive similar beats occurring by chance in any one patient in 1 minute is < 0.05 and < 0.0000001, respectively. There was a significant correlation (r= 0.90) between the amount of linking during the first and second minutes of atrial fibrillation in each patient.ConclusionsTransient similarities in the direction of wavelet propagation in the majority of patients with atrial fibrillation is consistent with the presence of transient linking. To our knowledge, this is the first direct evidence that atrial activation during atrial fibrillation in humans is not entirely random.

ISSN:0009-7322    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

BackgroundBody surface maps of net QRST deflection areas (isointegrals) reflect regional ventricular repolarization properties. Vulnerability to ventricular tachyarrhythmias is associated with maps that feature multiple islands (extrema) of positive and negative values; such maps reflect regional disparity of ventricular recovery properties. The value of body surface mapping in prediction of the efficacy of antiarrhythmic therapy for ventricular tachyarrhythmias has not been determined.Methods and ResultsIsointegral ECG body surface mapping was performed in 51 patients with inducible ventricular tachycardia having programmed stimulation studies at baseline and after oral quinidine therapy. The degree of nondipolarity of QRST isointegral distribution was expressed by the number of extrema and by the percentage contribution of nondipolar eigenvectors after Karhunen-Loeve transformation. QRST isointegral nondipolarity was greater in ventricular tachycardia patients than in 51 ageand sex-matched normal subjects expressed as mean number of extrema (4.1±2.8 versus 2.0±0.2, respectively), mean eigenvector-determined nondipolar content percentages (12.4±10.1% versus 4.5±4.9%), prevalence of abnormal numbers of extrema (63% versus 4%), or prevalence of abnormal nondipolar content percentages (33% versus 4%) (eachp< 0.01). Quinidine prevented ventricular tachycardia induction in 14 patients. Patients for whom quinidine was or was not effective had similar nondipolarity indexes at baseline. However, maps on quinidine differed as a function of antiarrhythmic efficacy. Although effective therapy produced no significant mean changes in nondipolarity, ineffective therapy increased the number of extrema compared with baseline (5.4±3.4 versus 3.8±2.5, respectively) (p= 0.002). Individually, 43% of patients on effective therapy had drug-induced decreases in numbers of extrema compared with 14% of those on ineffective therapy (p= 0.02). Furthermore, 29% of patients on effective therapy showed drug-induced increases in numbers of extrema compared with 62% of those on ineffective therapy (p= 0.03). Conclusions. QRST isointegral body surface mapping shows promise as a noninvasive measure of drug efficacy in patients with ventricular tachycardia.

ISSN:0009-7322    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

BackgroundProspective epidemiological studies indicate that elevated heart rate may carry increased risk for coronary heart disease. Little is known about the relation between heart rate and serum lipid and lipoprotein concentrations in the general population.Methods and ResultsWe assessed anthropometric and life-style determinants of heart rate and examined the association between heart rate and serum lipid and lipoprotein concentrations in a cross-sectional study of 9,719 men and 9,433 women 12–59 years old. Stratified and multivariate analyses were used to detect possible modification of effect and to control for confounding variables. Heart rate was positively associated with male sex and smoking, decreased with body height and physical activity, and showed a U-shaped relation to body mass index. In both sexes, there was a significant progressive increase in age-adjusted levels of total cholesterol, non–high density lipoprotein (HDL) cholesterol, and triglycerides and a decrease in HDL cholesterol with heart rate. Men with heart rate > 89 beats per minute had 14.5% higher non-HDL cholesterol and 36.3% higher triglyceride levels than men with heart rate < 60 beats per minute. The corresponding differences in women were 12.5% and 22.2%. The associations remained significant when anthropometric and life-style factors were controlled for. The slopes relating total and non-HDL cholesterol level to heart rate were steeper with advancing age.ConclusionsIncreases in heart rate correlate with higher levels of atherogenic serum lipid fractions in the general population. Alterations in aortic impedance and/or autonomic influences may underlie these associations.

ISSN:0009-7322    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

BackgroundCalifornia Seventh-Day Adventists have lower mortality rates from coronary heart disease (CHD) than other Californians. Associations between traditional risk factor and CHD events have not been reported previously for Adventists.Methods and ResultsA cohort study allowed 6 years of follow-up of 27,658 male and female California Seventh-Day Adventists. Data collected included age, sex, physician-diagnosed hypertension and diabetes mellitus, body height, weight, previous and current cigarette smoking habits, and current exercise habits. Incident cases of definite myocardial infarction (MI) and definite fatal CHD were diagnosed according to recognized criteria. Both stratified and proportional hazards analyses demonstrated that in this low-risk population, the above traditional coronary risk factors exhibit their usual associations with risk of CHD events. It was noted that exercise had a strong negative association with fatal CHD events (relative risks [RR], 1.0, 0.66, and 0.50 with increasing exercise) but no association with risk of MI (either nonfatal or all cases). Conversely, obesity was much more clearly associated with MI (RR, 1.0, 1.18, and 1.83 with increasing tertiles of obesity) than with fatal events. The importance of the risk factors was similar in both sexes, except that the effect of cigarette smoking seemed more pronounced in women.ConclusionsThe epidemiology of coronary heart disease in this low-risk California population appears to be at least qualitatively similar to that seen in other groups. There was evidence that the effects of exercise and obesity may differ depending on whether fatal CHD and MI (either all MI or nonfatal alone) is the end point.

ISSN:0009-7322    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

BackgroundThrombus regression in heparin-treated, acute deep venous thrombosis of the lower extremity is poorly documented in the literature; different rates of thrombus resolution and recanalization are reported.Methods and ResultsIn a prospective follow-up study, duplex scanning was used to evaluate the thrombus regression in patients with documented acute femoropopliteal thrombosis. Eighty vein segments in 20 legs of 18 patients were subjected to repeat duplex scans at 1, 3, 6, 12, and 26 weeks after diagnosis; 49 segments showed thrombus at diagnosis. The popliteal vein showed the highest thrombus load at diagnosis, followed in descending order by the superficial femoral, profunda femoris, and common femoral vein segments (p< 0.001). Thrombus regression was significant (p< 0.001) in all segments and proceeded at an exponential rate that was equal in the different vein segments of the upper leg. Both thrombus resolution and recanalization appeared to be a function of the initial thrombus load and could not be related to individual vein segments. Recanalization was seen in 23 of 31 initially occluded segments and occurred within the first 6 weeks after diagnosis in 20 of 23 segments. Extension of thrombus despite anticoagulant therapy was observed in 15 vein segments and was not related to the initial thrombosis score (p= 0.l) or individual vein segments (p= 0.23). Thrombus extension in seven patients with prethrombotic conditions was not different (p= 0.9) from the other patients.ConclusionsDuplex scanning is an important noninvasive tool to quantify thrombus regression in acute deep venous thrombosis in detail without unnecessary discomfort to the patient.

ISSN:0009-7322    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

BackgroundAn endogenous digitalis-like compound in mammals has long been postulated, but only recently has a substance indistinguishable from ouabain been identified in human plasma. Because of the potential significance of such a substance in patients with congestive heart failure, we sought to evaluate the pathophysiology of endogenous ouabain in these individuals.Methods and ResultsUsing an immunoassay, we determined plasma ouabain concentrations in 51 patients with heart failure and in 19 control subjects. Plasma ouabain concentrations in control subjects ranged from 0.16 to 0.77 nM (mean, 0.44±0.20 nM). In 19 matched heart failure patients receiving digoxin, the mean ouabain was significantly elevated at 1.59±2.2 nM (range, 0.17–8.76 nM,p< 0.05 versus control subjects). The ouabain concentration correlated inversely with both cardiac index (r= −0.62,p< 0.005) and mean arterial pressure (r= −0.51,p< 0.05). However, there was no correlation between ouabain and left ventricular filling (r= 0.19, NS) or right atrial pressures (r= 0.20, NS). In 16 heart failure patients not receiving digoxin, the mean ouabain was 1.52±2.58 nM. No relation between renal function and ouabain was detected.ConclusionsThe unanticipated lack of correlation of ouabain with atrial pressures indicates that volume is not the chief determinant of ouabain concentration in patients with congestive heart failure. However, the significant relations of plasma ouabain concentration with cardiac index and mean arterial pressure imply that endogenous ouabain may be an important homeostatic factor in humans.

ISSN:0009-7322    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

BackgroundChronic ischemic heart disease may lead to ventricular dilation and congestive heart failure (ischemic cardiomyopathy [ICM]). The changes in cardiac myocyte shape associated with this dilation, however, are not known.Methods and ResultsLeft ventricular myocyte dimensions were assessed in cells isolated from explanted human hearts obtained from patients with ICM (n= 6) who were undergoing heart transplantation. Cells were also examined from three nonfailing donor hearts with normal coronary arteries (NCA). Compared with cells from patients with NCA, myocyte length was 40% longer in hearts from patients with ICM (197±8 versus 141±9 pm,p< 0.01), cell width was not significantly different, and cell length/width ratio was 49% greater (11.2±0.9 versus 7.5±0.6,p< 0.01). Sarcomere length was the same in myocytes from both groups. The extent of myocyte lengthening is comparable to the increase in end-diastolic diameter commonly reported in patients with ICM.ConclusionsThese data suggest that increased myocyte length (an intracellular event), instead of myocyte slippage (an extracellular event), is largely responsible for the chamber dilation in ICM. Furthermore, maladaptive remodeling of myocyte shape (e.g., increased myocyte length/width ratio) may contribute to the elevated wall stress (e.g., increased chamber radius/wall thickness) in ICM.

ISSN:0009-7322    

出版商:OVID    

年代:1992

数据来源: OVID