Search PubMed⌕ Search

Biomedical subjects

M B Weiss

Publications and source records attributed to M B Weiss.

At least 37 records · Page 2Linked to original sources
PubMed1985

Serological evidence of Hantaan virus infection in the United States.

We found low titers of fluorescent antibodies against Hantaan virus, the etiologic agent of Korean hemorrhagic fever, in sera from 7 of 1,035 patients with febrile illnesses of unknown origin and from 6 of 664 blood donors in the United States. All but 1 of these individuals possessed neutralizing antibodies against Hantaan virus. This was a 31-year-old research technician who had worked with laboratory rodents with virus-induced tumors, but had not traveled abroad, suggesting that infection with Hantaan virus or a closely related agent was locally acquired. However, the precise source of his infection remains unclear.

Adult↗
PubMed1984

Percutaneous transluminal coronary angioplasty of a coronary artery with a total occlusion.

Percutaneous transluminal coronary angioplasty has become an accepted therapeutic modality for patients with coronary artery disease. Until the present, its use has been restricted to vessels that are subtotally obstructed. We recently successfully utilized coronary angioplasty in a patient with a totally occluded coronary artery. The experience is described and criteria proposed for the selection of patients with totally obstructed coronary arteries for coronary angioplasty.

Adult↗
PubMed1983

Diagnosis and classification of myocarditis by endomyocardial biopsy.

Myocarditis was diagnosed by endomyocardial biopsy in 34 patients with otherwise unexplained heart failure. On the basis of both clinical and histologic findings these patients were divided into three groups. Seven patients had acute myocarditis (mean age, 20 years; mean ejection fraction, 22 per cent) characterized by an interstitial inflammatory infiltrate and extensive, acute cell damage. Five of these patients died after a mean duration of illness of eight weeks. Eighteen patients had rapidly progressive myocarditis (mean age, 35 years; mean ejection fraction, 19 per cent) characterized by patchy acute and healing cell damage and fibrosis; 17 of them died after a mean duration of illness of 23 months. Nine patients had chronic myocarditis (mean age, 31 years; mean ejection fraction, 31 per cent) characterized by focal inflammation and cell damage. All nine were alive after a mean follow-up period of 39 months. In four of these nine, clinical and hemodynamic improvement occurred after one month of immunosuppressive therapy. Our study suggests that a clinically useful classification of myocarditis can be accomplished by endomyocardial biopsy.

Adult↗
PubMed1983

Validation of the angiographic accuracy of digital left ventriculography.

Digital subtraction angiography enhances the contrast to background signal, enabling the performance of angiography with reduced doses of contrast medium. The objectives of the present study were (1) to validate the accuracy of digital left ventriculography for measurement of left ventricular volumes and segmental contraction; and (2) to compare the hemodynamic effects resulting from low-and high-dose intraventricular contrast injections. Twenty-eight patients underwent digital left ventriculography, performed by intraventricular injection of 7 ml of contrast medium diluted in saline solution, followed by conventional cineangiography of the left ventricle performed with 45 ml of undiluted contrast medium. Left ventricular volumes calculated from digital ventriculograms correlated well with volumes calculated from conventional ventriculograms: end-diastolic volume (r = 0.97, standard error of estimate [SEE] 23.4 ml; end-systolic volume (r = 0.97, SEE 15.4 ml); stroke volume (r = 0.95, SEE 14.7 ml); and ejection fraction (r = 0.97, SEE 3.8%). Segmental left ventricular contraction, measured as percent chordal shortening of hemiaxes, correlated moderately well (r = 0.81, SEE 11.5%). After injection of undiluted contrast medium, left ventricular systolic pressure decreased (133 +/- 31 to 123.5 +/- 27 mm Hg; p less than 0.01) and left ventricular end-diastolic pressure increased (12.0 +/- 7 to 16.9 +/- 10 mm Hg; p less than 0.001). Left ventricular systolic and end-diastolic pressures did not change significantly after injection of diluted contrast medium, and patients had no discomfort. Thus, digital subtraction angiography permits the performance of left ventriculography with markedly reduced doses of contrast medium, obviating the hemodynamic effects resulting from injection of conventional doses of contrast medium. This new approach to left ventriculography provides high resolution ventriculograms for accurate measurement of left ventricular volumes, stroke volume, and ejection fraction.

Adult↗
PubMed1983

Kawasaki syndrome in an adult: endomyocardial histology and ventricular function during acute and recovery phases of illness.

Kawasaki syndrome, an acute systemic inflammatory illness of unknown origin usually affecting children, may develop into a serious illness complicated by coronary artery aneurysms or myocarditis. This report describes an adult with Kawasaki syndrome studied by right ventricular endomyocardial biopsy and cardiac catheterization during the acute and recovery phases of illness. The initial biopsy specimen showed acute myocarditis and was associated with hemodynamic evidence of biventricular dysfunction, a severely depressed left ventricular ejection fraction and global hypokinesia. With time, there was spontaneous and rapid resolution of the inflammatory cell infiltrate with concurrent return to normal myocardial function. Right ventricular endomyocardial biopsy studies early in the course of the cardiac disease associated with Kawasaki syndrome may correlate with ventricular function and may be useful for monitoring immunosuppressive therapy in patients with this syndrome.

Adult↗
PubMed1983

Relationship between segmental thallium-201 uptake and regional myocardial blood flow in patients with coronary artery disease.

The relationship between the spatial distribution of thallium-201 in myocardial perfusion scintigrams and the distribution of left ventricular regional myocardial blood flow was examined in 25 patients undergoing coronary arteriography. Thallium-201 myocardial scintigrams were obtained after symptom-limited exercise and after a 4 hr delay. Regional myocardial blood flow was measured by the xenon-133 clearance method in patients at rest and during rapid atrial pacing to a double product comparable with that achieved during exercise stress testing. Patterns of regional thallium-201 activity and regional myocardial blood flow, recorded in similar left anterior oblique projections, were compared for left ventricular segments supplied by the left anterior descending (LAD) and left circumflex (CIRC) arteries. In 11 patients without significant lesions of the left coronary artery (group 1), thallium-201 was homogeneously distributed in the LAD and CIRC distributions in scintigrams taken during peak exercise; these scintigrams correspond to homogeneous regional myocardial blood flow in the LAD and CIRC regions during pacing-induced stress. In 14 patients with significant lesions of the left coronary artery (group 2), ratios of regional thallium-201 activity in the LAD and CIRC distributions of exercise scintigrams correlated well (r = .84) with ratios of regional myocardial blood flow measured during rapid pacing. Background subtraction altered the relationship between relative thallium-201 uptake and regional myocardial blood flow, causing overestimation of the magnitude of flow reduction on exercise scintigrams. These data indicate that: (1) in patients with normal left coronary arteries, thallium-201 is homogeneously distributed to the left ventricle, reflecting the homogeneous distribution of regional myocardial blood flow over a wide range of mean left ventricular flow rates and (2) in patients with significant lesions of the left coronary artery, the relative spatial distribution of thallium-201 activity in exercise perfusion scintigrams reflects the distribution of regional myocardial blood flow.

Adult↗
PubMed1982

The effect of captopril on renal, coronary, and systemic hemodynamics in patients with severe congestive heart failure.

The effects of captopril (CPT), an oral angiotensin-converting enzyme (ACE) inhibitor, on systemic failure (CHF). In 15 patients, CPT decreased mean arterial pressure from 75 +/- 3 to 60 +/- 3 mm Hg associated with a 16% increase in cardiac output, a 24% reduction in systemic vascular resistance, and a 36% decrease in pulmonary capillary wedge pressure (all p less than 0.01). Despite the improved cardiac output, renal blood flow, creatinine clearance, and sodium excretion did not rise during the first 2 days of CPT therapy. In eight patients, coronary sinus blood flow diminished from 98 +/- 11 to 82 +/- 9 ml/min (p less than 0.01) following drug administration in association with a fall in arterial pressure and heart rate but no change in coronary sinus oxygen inhibitor failed to improve renal hemodynamics. In addition, initial CPT administration produced a decrease in coronary blood flow that was related to a decrease in myocardial oxygen requirements.

Captopril↗
PubMed1982

Development of a new endosseous dental implant. Part II: Human studies.

The development of an endosseous implant has followed a logical and formal plan. 1. Extensive experiments with animals provided preliminary statistics of successful function, extensive histologic studies, evaluation of biocompatibility, and a preliminary assessment of contraindications. 2. Carefully developed and controlled clinical study of human subjects with frequent examinations and detailed records of both successes and failures again provided new bases for contraindications. The statistics on the clinical study are satisfactory in their results, although they should be regarded as having a somewhat conservative slant. This is because implant failures became a learning base for improved procedures. The program so far has been limited to a single implant design that, with size variants, will serve most applications. However, it is not feasible to modify the design in terms of dimensions for application in the anterior portion of the mouth. A design for this purpose is established on paper and will become a future additional development.

Adult↗
PubMed1982

Left ventricular myocardial blood flow in multivessel coronary artery disease.

The relationship between resting left ventricular (LV) myocardial blood flow (MBF) and hemodynamic determinants of myocardial oxygen consumption was investigated in 15 patients with multivessel coronary artery disease (CAD) and in 10 patients with normal coronary arteriograms. Mean LV MBF per unit mass of tissue was measured with a multicrystal scintillation camera from the regional clearance rates of xenon-133 injected into the left main coronary artery. Peak LV wall stress, mean velocity of circumferential fiber shortening (Vcf), rate of ejection during the first third of systole (1/3 SV), LV ejection fraction (EF), and the ratio of peak LV systolic pressure to LV end-systolic volume were measured by contrast left ventriculography. Mean LV MBF per unit mass was significantly reduced (48 +/- 11 vs 67 +/- 12 ml/100 g.min; p less than 0.01) in patients with multivessel CAD. However, none of the patients with CAD experienced chest pain or had electrocardiographic evidence of myocardial ischemia during the resting MBF measurements. Ejection phase indexes were lower in the patients with CAD: LVEF (56 +/- 10% vs 64 +/- 7%, p less than 0.05); 1/3 SV (35 +/- 3 vs 44 +/- 4%, p less than 0.05); and mean Vcf (1.05 +/- 0.30 vs 1.19 +/- 0.27 circ/sec, NS). LV wall thickness (9.8 +/- 1.9 vs 7.5 +/- 1.4 mm, p less than 0.01) and LV mass index (94 +/- 32 vs 64 +/- 17 g/m2, p less than 0.05) were significantly increased in the patients with CAD, accounting for the reduction in peak LV wall stress (276 +/- 73 vs 373 +/- 91 dyn-cm-2 x 10(-3), p less than 0.05) observed in these patients. Multiple regression analysis indicated that indexes of three of the major determinants of myocardial oxygen consumption explained 65% of the variation in MBF in patients with CAD: peak LV stress, mean Vcf and heart rate. After adjustment for these three indexes, the average LV MBF rates were not significantly different in the two patient groups (54.8 +/- 1.8 vs 57.6 +/- 2.3 ml/100 g.min). In both groups, resting LV MBF/beat correlated most highly with peak LV wall stress (r = 0.79). Thus, the reduction in LV MBF per unit mass observed in patients with multivessel CAD at rest is related to lower levels of hemodynamic variables that determine myocardial oxygen consumption. Peak LV wall stress is the most important hemodynamic variable determining the level of resting MBF in patients with and without CAD.

Adult↗
PubMed1981

Percutaneous intraaortic balloon insertion in patients with aortoiliac disease.

A new technique for percutaneous insertion of intraaortic balloon catheters in patients with tortuous or narrowed external iliac arteries is described. This method uses a long (45 cm) 12F sheath, which extends up to the descending aorta and protects the iliac artery and aorta from injury during insertion of the balloon catheter. Insertion of intraaortic balloon catheters was not possible by conventional percutaneous technique in six patients with severe acute myocardial ischemia. Use of the long sheath approach permitted rapid and successful institution of circulatory support in these patients.

Adult↗
PubMed1980

Percutaneous intraaortic balloon insertion.

A new single chambered percutaneous intraaortic balloon has been constructed around a central guidewire. The balloon can be wrapped around the guidewire, enabling its insertion into the femoral artery through a 12F sheath inserted with the conventional Seldinger technique. Percutaneous intraaortic balloon insertion has been performed in 27 patients (mean age 58 years) for a variety of medical and surgical indications. Percutaneous balloons could not be advanced into the aorta in two patients (7.4 percent) with severe bilateral aortoiliac occlusive disease. In all 25 patients undergoing intraaortic balloon pumping satisfactory circulatory support was achieved, and 21 (84 percent) of the patients survived to be discharged from the hospital. The mean duration of intraaortic balloon pumping was 3.5 days. Percutaneous intraaortic balloon insertion requires less than 5 minutes and has been successfully performed in the cardiac catheterization laboratory, coronary care unit, operating room and recovery room. After direct balloon removal, external pressure was applied for 30 minutes. No patient experienced hematoma of the groin, aortic dissection, compromised distal pulses or late wound complications. Percutaneous balloon insertion permits the rapid institution of circulatory support and broadens the medical and surgical applications of intraaortic balloon pumping.

Adult↗
PubMed1980

Method for recording electrical activity of the sinoatrial node and automatic atrial foci during cardiac catheterization in human subjects.

A method for recording electrical activity of the sinoatrial (S-A) node and automatic atrial foci in human subjects is described. To record S-A nodal electrograms, an electrode catheter was inserted percutaneously into the femoral vein and advanced under fluoroscopic control to the superior vena caval-right atrial junction. The distal terminal of the catheter was placed in the area of the S-A node and the proximal terminal on the free right atrial wall or in the right atrial lumen. Polarity was reversed from the conventional electrocardiographic recording; high amplification (about 100 microV/cm) and selective filters (0.1 to 20 hertz) were used. S-A nodal electrograms recorded with this method in human subjects were similar to electrograms obtained previously from the dog and rabbit and revealed negatively directed diastolic and upstroke slopes preceding the P wave of the electrocardiogram. Sinoatrial conduction time measured from the S-A nodal electrograms in 15 cases was 34.9 +/- 2.1 ms(mean +/- standard error of the mean) for a sinus cycle length of 736.4 +/- 38.6 ms. The coronary sinus electrograms in a patient with coronary sinus rhythm were recorded by the same technique except that the distal terminal of the catheter was placed at the coronary sinus ostium. A negatively directed diastolic slope preceding the P wave was consistently recorded. This method for recording electrograms of the S-A node and ectopic automatic atrial foci should prove useful in (1) assessment of both normal and abnormal S-A nodal function, (2) direct determination of conduction time from the S-A nodal pacemaker to the atrium, and (3) localization of automatic atrial foci.

Adolescent↗
PubMed1980

Improved exercise ejection fraction with long-term prazosin therapy in patients with heart failure.

To study the effect of prazosin therapy on left ventricular function in patients with chronic stable heart failure, first pass radionuclide angiography at rest and during exercise was performed in 15 patients before the administration of prazosin and after seven to 12 weeks of prazosin therapy. There was no significant change in resting ejection fraction before and during prazosin therapy (36 +/- 14 per cent versus 37 +/- 14 per cent) (mean +/- standard deviation). However, exercise ejection fraction increased from 34 +/- 14 per cent to 42 +/- 17 per cent (p less than 0.01). The difference in ejection fraction from rest to exercise (ejection fraction response) changed significantly from -2 +/- 6 per cent before prazosin therapy to +5 +/- 7 per cent during prazosin therapy (p less than 0.01). Exercise duration increased from 368 +/- 82 seconds to 476 +/- 82 seconds (p less than 0.01). Total work capacity measured in kilojoules increased from 12.6 +/- 8.3 to 18.6 +/- 10.4 (p less than 0.01). The improved ejection fraction response during prazosin therapy correlated with the improved work capacity (r = 0.69, p less than 0.01) and exercise duration (p = 0.59, p less than 0.05). This improvement occurred despite a significant weight gain with prazosin from 72.2 +/- 20.8 kg to 73.5 +/- 20.8 kg (p less than 0.01). These data suggest that long-term prazosin therapy is effective in the treatment of heart failure. However, the beneficial effects of prazosin, an alpha 1 blocking agent, may be evident only during exercise.

Adult↗
PubMed1980

Coronary occlusion and reperfusion: effects on subendocardial cardiac fibers.

Coronary flow and transmembrane potentials of Purkinje and muscle fibers in reperfused infarcts and infarcts caused by permanent coronary occlusion were compared. Purkinje fibers in permanently occluded infarcts at 24 h had markedly reduced resting potentials. Action potential amplitudes, and Vmax were reduced and duration markedly prolonged. In reperfused infarcts, changes in Purkinje fiber transmembrane potentials were not as marked. Action potential duration in 3-day-old permanently occluded infarcts were longer than at 24 h, but in reperfused infarcts durations had returned to normal. Premature impulses conducted more rapidly in the reperfused infarct Purkinje system than in the permanently occluded. Other transmembrane potential parameters of Purkinje fibers in 3-day-old and 9- to 10-day-old reperfused and permanently occluded infarcts were not significantly different from each other. The ventricular muscle cells that survived in reperfused infarcts at all times also had reduced resting potentials and action potentials with decreased amplitudes, reduced Vmax, and prolonged durations. Almost no muscle cells survived in permanently occluded infarcts. Therefore, reperfusion salvages subendocardial fibers and prevents some but not all of the electrophysiological abnormalities.

Action Potentials↗
PubMed1980

The human sinus node electrogram: a transvenous catheter technique and a comparison of directly measured and indirectly estimated sinoatrial conduction time in adults.

To improve methods for evaluating human sinus node function (SNF), we developed a transvenous electrode catheter technique for direct recording of sinus node electrograms in adults. Sinus node electrograms (SNE) characterized by low-frequency, anatomically localized pre-P-wave potentials were obtained in 19 of 23 patients. The SNE configuration was similar to that previously found for endocardial SNE recordings in in vitro atrial preparations, in open-chest dogs and during human open heart surgery. In 16 patients with normal SNF, directly recorded sinoatrial conduction times (SACTs) were 46-116 msec. In three patients with sick sinus syndrome, SACT was 110-126 msec. In 15 of the 19 patients, SACT was estimated by the atrial premature stimulus technique and was compared with the directly measured SACT. When atrial premature depolarizations produced no sinus node depression, the mean differences between the direct and estimated SACT was 1.8 +/- 5.6 msec.

Adult↗