Biomedical subjects

M C Limacher

Publications and source records attributed to M C Limacher.

47 records · Page 3Linked to original sources

PubMed1985

Tricuspid regurgitation during pregnancy: two-dimensional and pulsed Doppler echocardiographic observations.

Although precordial murmurs occur frequently during pregnancy, their origin is rarely known. To investigate the nature of these murmurs, 2-dimensional (2-D) and pulsed Doppler echocardiography was performed in 81 asymptomatic pregnant women who had new systolic precordial murmurs. End-systolic right atrial dimensions, early diastolic tricuspid anular diameters, and end-diastolic right ventricular diameters were measured from the apical 4-chamber view and compared with measurements from 26 young nonpregnant women without known heart disease. Tricuspid regurgitation (TR) was detected by pulsed Doppler echocardiography in 35 of 81 pregnant women. Thirty-two pregnant women had normal 2-dimensional and pulsed Doppler echocardiographic findings. Other valvular or congenital lesions were detected in 14 pregnant women. The right-sided intracardiac diameters were larger in all groups of pregnant women than in non-pregnant control subjects (p less than 0.001). The tricuspid anular diameter was larger in the pregnant women with TR than in pregnant women with normal pulsed Doppler echocardiographic findings (24 +/- 2 vs 22 +/- 3 mm, p less than 0.015). No patient had clinical difficulty associated with a murmur. Functional TR, therefore, often occurs in pregnancy and appears to be a result of dilation of the tricuspid anulus. TR may contribute to the development of murmurs in pregnant women.

Adolescent↗

PubMed1985

Cardiac evaluation following heart injury.

Both penetrating and blunt cardiac injuries require urgent management. Delayed sequelae and complications have been reported to occur in 4 to 56% of survivors and frequently required secondary surgical corrections. Between January 1980 and June 1984, 204 patients presented with heart injuries. One hundred twenty-eight of these patients survived. Of the 90 undergoing cardiorrhaphy in the operating room, 78 survived. Two-dimensional (2-D) and pulsed-Doppler echocardiography (echo) and/or cardiac catheterization were performed in 40 patients for suspected significant residual injury. Eight of the 40 required secondary cardiac operations. Two-dimensional echo demonstrated pericardial effusion, abnormal chamber enlargement, abnormal cardiac wall motion, intracardiac missile, and intracardiac and pleural thrombus. Pulsed-Doppler findings included ventricular septal defect, tricuspid insufficiency and right ventricular turbulence secondary to arteriovenous fistulae. Cardiac catheterization detected lesions undetected by 2-D echo in one patient with a gunshot wound. It is concluded that in the absence of cardiac bullets seen on routine chest X-ray, 2-D with pulsed-Doppler echo is an excellent screening technique. With a positive echo study or a residual bullet overlying the cardiac silhouette, cardiac catheterization is indicated in selected patients.

Adolescent↗

PubMed1985

Determination of parameters of left ventricular diastolic filling with pulsed Doppler echocardiography: comparison with cineangiography.

To determine the relationship between Doppler-derived flow velocity through the mitral anulus and angiographic parameters of left ventricular filling, 30 patients were studied by two-dimensional echocardiography combined with pulsed Doppler echocardiography followed within 1 hr by left ventricular angiography. The average heart rate for each test was 69 beats/min. Doppler-derived parameters included: early peak diastolic velocity (E) and peak atrial velocity, peak filling rate computed as E X cross-sectional area of the mitral anulus derived from the annular diameter, normalized peak filling rate computed as peak filling rate divided by the left ventricular end-diastolic volume determined by two-dimensional echocardiography, and half filling fraction derived from the time-velocity integral of the Doppler-determined velocity curve. Frame-by-frame left ventricular volumes were obtained throughout diastole from single-plane cineangiograms. A volume-time curve with its derivative was generated by computer processing from which peak filling rate, normalized peak filling rate, and half filling fraction were measured. Morphologically, the Doppler-derived velocity profile resembled the derivative of the angiographic volume curve. In patients with reduced angiographic peak filling rates, early peak diastolic velocity was often decreased less than 45 cm/sec with a relative increase in peak atrial velocity resulting in an early peak diastolic velocity to peak atrial velocity ratio less than 1.0. There were no significant differences in mean values for peak filling rate, normalized peak filling rate, and half filling fraction by Doppler echocardiography vs angiography (296 vs 283 ml/sec, 1.9 vs 2.0 sec-1 and 0.55 vs 0.55, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1984

Pulsed Doppler echocardiographic determination of stroke volume and cardiac output: clinical validation of two new methods using the apical window.

Two methods of measuring stroke volume and cardiac output with pulsed Doppler two-dimensional echocardiography were developed and validated against the thermodilution technique in 39 patients, 33 of which were in an intensive care unit. With the use of the apical four-chamber view, a mitral inflow method combined the velocity of left ventricular inflow at the mitral anulus with the cross-sectional area of the anulus calculated from its diameter at middiastole (area = pi r2). From the apical five-chamber view a left ventricular outflow method combined the velocity of left ventricular outflow with the cross-sectional area of the aortic anulus calculated from its diameter during early systole (parasternal long-axis view). Measurements with the mitral inflow and left ventricular outflow methods were obtained in 35 of 39 (90%) and 39 of 39 (100%) patients, respectively. Validation of the mitral method excluded patients with mitral regurgitation (n = 11) and validation of the left ventricular outflow method excluded those with aortic regurgitation (n = 4). Good correlations were observed between thermodilution and Doppler measurements of stroke volume and cardiac output for both the mitral anulus method (R = .96 and .87, respectively) and the left ventricular outflow method (R = .95 and .91, respectively). The results of the two methods correlated well with each other in patients without regurgitant valve lesions. A greater interobserver variability was observed with the mitral anulus method, which was related solely to greater variability in measuring the annular diameter.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1983

Induction of clinical ventricular tachycardia using programmed stimulation: value of third and fourth extrastimuli.

Initiation of ventricular tachycardia (VT) by right ventricular extrastimulation was analyzed in 142 consecutive patients, 53 with electrocardiographically documented episodes of spontaneous VT or ventricular fibrillation (VF) and 68 with no spontaneous VT or VF; 21 patients with a history of sudden death but no documented arrhythmia were excluded from further analysis. All patients received 1 to 4 extrastimuli (S2, S3, S4 and S5) during pacing at fixed cycle lengths of 600 or 500 msec at 1 or 2 right ventricular sites. Clinical VT was reproduced by extrastimulation in 28 of 43 patients (65%) with sustained VT and in 0 of 10 patients with nonsustained VT. Clinical VT was induced by S2 or S3 in 16 patients and by S4 or S5 in 12 patients. Ventricular burst pacing reproduced clinical VT in 3 other patients. Nonclinical VT, which was most often polymorphic and nonsustained, was induced in 24 of 121 patients (20%), in 11 by S2 or S3 and in 13 by S4 or S5. Ventricular burst pacing induced nonclinical VT in 4 other patients. In patients with spontaneous sustained VT, the use of S4 and S5 in the right ventricle increases the yield of inducible clinical VT compared with use of S2 and S3 alone, but at a cost of increased induction of nonclinical VT. Frequent induction of nonclinical VT limits the interpretation of the results of such stimulation in patients without previously documented VT.

Adult↗

PubMed1983

Cardiac echinococcal cyst: diagnosis by two-dimensional echocardiography.

A case of an intracardiac echinococcal cyst is presented. The diagnosis was made by two-dimensional echocardiography, which clearly identified a large multiseptated cystic structure in the right ventricular outflow tract. The findings were verified at surgery. It is suggested that two-dimensional echocardiography may be the procedure of choice in the diagnosis of cardiac echinococcal disease.

Adult↗

PubMed1983

Detection of coronary artery disease with exercise two-dimensional echocardiography. Description of a clinically applicable method and comparison with radionuclide ventriculography.

Two-dimensional echocardiography (2-D echo) was performed in 73 patients evaluated for coronary artery disease (CAD) and in four normal volunteers before and immediately after a maximal treadmill exercise test. Diagnostic images were obtained from the apical and parasternal windows. In 17 patients with normal coronary arteriograms, ejection fraction (EF) increased from 66 +/- 9% (+/- SD) at rest to 73 +/- 8% after exercise (p less than 0.001), while in 56 patients with proved CAD, EF fell from 56 +/- 13% at rest to 53 +/- 16% after exercise (p less than 0.01). The sensitivity of postexercise 2-D echo for detecting CAD (based on abnormal EF response and/or regional dyssynergy) was 91% (51 of 56 patients) and the specificity was 88% (15 of 17). Sensitivity for one-, two- and three-vessel disease was 64% (seven of 11), 95% (20 of 21) and 100%, respectively. Patients with multivessel disease showed a significant fall in a wall motion score index, from 0.79 +/- 0.25 to 0.63 +/- 0.26. Exercise radionuclide ventriculography (RNV) was also performed in 41 of the subjects (17 normals and 24 CAD patients) on a bicycle ergometer. The overall sensitivity of 2-D echo in this subgroup was 92%, compared with 71% for RNV. The sensitivity of 2-D echo for one-vessel disease (n = 4) was 50%, that for two-vessel disease (n = 12) was 100% and that for three-vessel disease (n = 12) was 100%. Respective values for RNV were 0%, 80% and 90%. The specificity of 2-D echo was 88% and that of RNV was 82%. A significantly higher peak heart rate response was observed on the treadmill than on the bicycle ergometer in both CAD patients and normal subjects. We conclude that postexercise 2-D echo is a clinically applicable technique for the diagnosis and evaluation of CAD patients and compares favorably with exercise RNV.

Adult↗

PubMed1978

Chemical pneumonitis after the intravenous injection of hydrocarbon.

A case reported in which a man intravenously injected himself with a hydrocarbon insecticide. The radiographic findings and clinical course were typical for hydrocarbon pneumonia. Symptoms developed almost immediately and radiographic findings cleared within 72 hours. Because the hydrocarbon was introduced intravenously, the role of aspiration in the development of hydrocarbon pneumonitis is obviated.

Adult↗

PubMedDate not supplied

A second-generation computer-based edge detection algorithm for short-axis, two-dimensional echocardiographic images: accuracy and improvement in interobserver variability.

The present study tested the hypothesis that a second-generation endocardial edge detection algorithm that used a priori endocardial and epicardial information would improve accuracy and reduce the variability of border definition. Five nonexpert observers utilized the version 2 algorithm on 20 cycles of two-dimensional short-axis images (five excellent, seven good, and eight poor quality studies stored digitally from a previously reported project). Manually defined areas by five recognized experts on these 20 cardiac cycles were considered to be "true areas." Areas defined by the experts with version 1 of the algorithm were also used for comparison. Regression of the version 2 areas with mean, manually defined excellent quality areas yielded a similar correlation (r = 0.985) to that reported between the manual and the version 1 areas (r = 0.986). For all 20 cycles in the series, however, the correlation between version 2 and the manually defined areas was lower (r = 0.952) than that of the same correlation with version 1 areas (r = 0.980). For all studies the interobserver variability (percent area difference) was +/- 14.4% for manually defined borders, +/- 11.1% for version 1-defined borders, and +/- 7.7% for version 2-defined borders. No difference in variability was observed for excellent quality studies (+/- 5.3% versus 5.2%) between version 1 and version 2 areas. However, the version 2 algorithm significantly reduced interobserver variability for good and poor quality studies (+/- 8.4% to 7.6%, p less than 0.025, and 16.3% to 9.1%, p less than 0.05, respectively). We concluded that: the version 2 algorithm provided accuracy and significantly reduced the variability of area measurement in good and poor quality studies and that epicardial information was important to the improvement by providing wall thickness information to assist in filling areas of dropout and avoidance of intracavitary structures.

Algorithms↗

PubMedDate not supplied

Skeletal muscle strength in heart transplant recipients.

Knee extension (quadriceps) strength, peak oxygen consumption, and body composition were measured in 11 orthotopic heart transplant recipients (50 +/- 14 years of age) 18 +/- 12 months after transplantation and 11 untrained sedentary control subjects closely matched (p > or = 0.05) with respect to age, height, and weight. Peak oxygen consumption and absolute knee extension strength in the transplant recipients were 57% and 69% of control, respectively. Leg strength and peak oxygen consumption were not significantly correlated (p > or = 0.05) with months after transplantation. Peak oxygen consumption was significantly (p < or = 0.05) correlated with leg strength in both groups, but the relationship was greater in transplant recipients (r = 0.90) compared with the control group (r = 0.65). These data indicate that a leg-strength deficit persists up to 18 months after transplantation and the decrement in peak oxygen consumption observed in heart transplant recipients is partially explicable by skeletal muscle weakness. Our results underline the importance of progressive resistance training in comprehensive rehabilitation programs.

Exercise Test↗

PubMedDate not supplied

Coronary heart disease in women. Past gaps, present state and future promises.

Women in the United States are more likely to die of coronary heart disease than any other cause. Determining risk for future disease events can be aided by a full assessment of risk factors and behaviors, but it should be noted that some factors, for example, diabetes and HDL cholesterol, impact a woman's risk differently than for a man. Studies evaluating women have shown a lower referral rate for catheterization and higher mortality rates following myocardial infarction and bypass surgery. Differentiating practitioner and patient biases from biological explanations is a challenge of future research. The possibility of hormone replacement therapy preventing coronary heart disease has given rise to the landmark NIH sponsored "Women's Health Initiative" which will provide definitive answers about the risks and benefits of long-term hormone treatment and dietary modification on coronary heart disease and cancer.

Aged↗