Search PubMed⌕ Search

Biomedical subjects

V Maranhao

Publications and source records attributed to V Maranhao.

At least 55 records · Page 3Linked to original sources
PubMed1984

Transcatheter laser dissolution of human atherosclerotic plaques: a model for testing catheters and techniques.

We constructed a model of the human arterial circulation that can be used to test laser angioplasty catheters and techniques on obstructed human coronary arteries under simulated physiologic conditions of blood pressure and flow. In this model system, a balloon-tipped catheter with a central, 0.02-cm light fiber was used to deliver 4 W of laser energy to two obstructed human cadaver coronary artery segments and four normal dog femoral artery segments. Flushing the catheter with saline during the lases minimized lateral thermal tissue damage. Channels were created in the obstructed arteries that were twice the diameter of the light fiber used to lase. One of four dog arteries perforated, underscoring the potential hazards of the procedure and the need for laser catheters that are flexible and capable of precise alignment.

Angioplasty, Balloon↗
PubMed1984

Emergency guide wire pacing: new methods for rapid conversion of a cardiac catheter into a pacemaker.

We developed a new electrode to convert rapidly a previously inserted pulmonary artery or left ventricular catheter into a pacemaker. One method of doing this is by withdrawal of the pulmonary artery catheter from the pulmonary artery to the right ventricle by pressure control, and a Teflon-coated guide wire, stripped of 5 mm of insulation at its tip, is advanced through the catheter to contact the endocardium. In the second method, the pacing electrode is advanced through the distal lumen of the catheter while it is positioned within the pulmonary artery and withdrawn into the right ventricle while pacing. Finally, a third method involves advancement of the guide wire electrode into the left ventricle through a pigtail catheter. To pace, the guide wire electrode is connected to the cathode of a pacemaker referenced to a skin electrode. We paced 10 of 10 right heart cardiac catheterization, intra- and postoperative surgery patients by methods 1 and 2, and 4 of 4 left heart catheterization patients by method 3. Thresholds (mean +/- SEM) for guide wire pacing were: right ventricle 1.52 +/- 0.4 mA; left ventricle 1.33 +/- 0.1 mA. Guide wire pacing is rapid, reliable, and requires little operator skill. Our indications for guide wire pacing are: 1) emergency right ventricular pacing in operative or intensive care unit patients with unexpected bradyarrhythmias who have an indwelling pulmonary artery catheter; and 2) emergency left ventricular pacing in left heart cardiac catheterization patients with contrast-induced bradyarrhythmias.

Bradycardia↗
PubMed1983

New method: calculation of magnification factor from an intracardiac marker.

In order to calculate a magnification factor (MF), an intracardiac marker (pigtail catheter with markers) was evaluated using a new formula and correlated with the conventional grid method. By applying the Pythagorean theorem and trigonometry, a new formula was developed, which is (formula; see text) In an experimental study, MF by the intracardiac markers was 0.71 +/- 0.15 (M +/- SD) and one by the grid method was 0.72 +/- 0.15, with a correlation coefficient of 0.96. In patients study, MF by the intracardiac markers was 0.77 +/- 0.06 and one by the grid method was 0.77 +/- 0.05. We conclude that this new method is simple and the results were comparable to the conventional grid method at mid-chest level.

Cardiac Catheterization↗
PubMed1983

Coronary artery obstruction due to blunt chest trauma with residual angina pectoris.

A 41-year-old man developed persistent angina pectoris following blunt trauma to his chest. Three months after the injury coronary angiography demonstrated 80% obstruction of the mid-left anterior descending coronary artery. There was no evidence of atherosclerosis in the remaining coronary arteries. Therefore the assumption is made that blunt trauma can induce incomplete coronary occlusion resulting in classic angina pectoris in apparently otherwise normal coronary arteries. The suggested mechanism of injury to the coronary vessel is either intimal tear and/or subintimal hemorrhage with incomplete luminal thrombosis.

Adult↗
PubMed1983

The use of the hepatic pressure maneuver to identify the murmur of tricuspid regurgitation.

To enhance the bedside diagnosis of tricuspid regurgitation, the influence of manual pressure applied below the liver on lower left sternal border murmurs was determined in 23 patients. All 23 subjects had right ventriculograms and right atrial phonocardiograms. The sign was positive in 13 cases, including 3 who were without a Carvallo sign. The application of manual pressure below the liver is a simple and valid additional maneuver for identifying the murmur of tricuspid regurgitation.

Adult↗
PubMed1982

Sequential study of left ventricular function in aortic valvular stenosis.

To assess the progression of aortic valvular gradients (AVG) and their relation to left ventricular function, 21 patients with aortic valvular stenosis were studied sequentially by cardiac catheterization and left ventriculography. All AVG were obtained from the left ventricle to ascending aortic pullback tracings. The ejection fraction and mean velocity of circumferential fiber shortening were obtained from left ventriculograms. A new onset of syncopal episode was helpful to predict the progression of AVG in five patients, but in others the progression of aortic stenosis was generally not predictable. The left ventricular contractility of these patients was usually normal, but seven patients exhibited the progressive impairment that was not proportional to the change of AVG and was clinically unrecognized. Also, the left ventricular function may deteriorate in the absence of progression of the aortic valvular gradient. Thus, serial hemodynamic studies could be indicated in patients with mild to moderate aortic stenosis even in the absence of new symptoms and signs.

Adult↗
PubMed1982

Diagnosis of severe tricuspid regurgitation.

Fifty-nine patients were studied who had severe tricuspid regurgitation which was confirmed by right ventriculography and during surgery in order to determine the incidence of clinical, radiologic, and hemodynamic clues of severe tricuspid regurgitation. Eighty-eight percent of patients had Carvallo sign alone or in combination with pulsatile liver or prominent jugular venous V waves, and the classic triad was present in 42 percent. Most patients had enlargement of the right atrium on chest x-ray film. The classical "ventricularization" pattern of right atrial pressure was seen in 30 percent, prominent V waves with rapid Y descents were present in 37 percent, and normal contour of right atrial waves with normal mean pressure was seen in 33 percent. The inspiratory maneuver was helpful to induce the ventricularization pattern or prominent V waves with rapid Y descents especially in patients with normal right atrial pressure waves. In conclusion, right ventriculography is a sensitive and accurate method for detecting and quantitating tricuspid regurgitation in the absence of the diagnostic physical findings.

Adult↗
PubMed1981

Giant Lambl's excrescences of papillary muscle and aortic valve: echocardiographic, angiographic, and pathologic findings.

A 54-year-old female with rheumatic heart disease was found to have a mass in the left ventricle by echocardiography and angiography. Subsequently, giant Lambl's excrescences of papillary muscle and aortic valve were confirmed by operation and pathologic examination. Possible complication from cardiac catheterization could be avoided by the utilization of echocardiography prior to catheterization.

Aortic Valve↗
PubMed1981

Intracardiac phonocardiography in tricuspid regurgitation: relation to clinical and angiographic findings.

Intracardiac phonocardiograms were obtained from the right atrium in order to study the relation between the clinical signs of tricuspid regurgitation, intracardiac murmurs and the degree of regurgitation demonstrated on right ventriculography with use of a preshaped catheter. In five patients with no heart disease, right ventriculograms showed no evidence of tricuspid regurgitation and intracardiac phonocardiograms in the right atrium demonstrated no murmur. Among 35 patients with valvular heart disease, a Carvallo sign (increased intensity of systolic murmur during inspiration) was present in 19 and absent in 16. All 19 patients with a Carvallo sign had variable degrees of tricuspid regurgitation on right ventriculography, and intracardiac phonocardiograms were positive for tricuspid regurgitation in 18. Among 16 patients with an absent Carvallo sign, neither right ventriculography nor intracardiac phonocardiography was indicative of tricuspid regurgitation in 5. Five patients had 1+ regurgitation and the intracardiac phonocardiogram was positive in three of these five patients. The other six patients showed 3+ to 4+ regurgitation and the intracardiac phonocardiogram was positive for tricuspid regurgitation in all. In conclusion, (1) the Carvallo sign is a reliable indicator of tricuspid regurgitation but its absence does not rule it out, and (2) right ventriculography using a preshaped catheter and intracardiac phonocardiography are useful in detecting clinically unrecognized tricuspid regurgitation.

Adult↗
PubMed1981

Tricuspid regurgitation by radionuclide angiography and contrast right ventriculography: a preliminary observation.

In a retrospective study correlating the degree of tricuspid regurgitation seen on first-pass radionuclide angiography with that seen on contrast right ventriculography in 51 patients, ten had no tricuspid regurgitation by contrast ventriculography, whereas by radionuclide angiography nine had no regurgitation and one had minimal regurgitation. Of eight patients with minimal tricuspid regurgitation by contrast ventriculography, five had minimal regurgitation by nuclide angiography and three had no regurgitation. Of the 11 patients with mild to moderate tricuspid regurgitation by contrast studies, ten had mild to moderate regurgitation and one had severe regurgitation by nuclide angiography. Of 22 patients with moderate to severe tricuspid regurgitation by contrast studies, 15 had moderate to severe regurgitation and seven had mild to moderate regurgitation by nuclear angiography. In this preliminary study comparing radionuclide angiography with contrast right ventriculography, there were three false-negative and one false-positive nuclide angiograms, giving a sensitivity of 93% and a specificity of 90%.

Adult↗
PubMed1981

Ventricular function before and after mitral valve replacement.

To evaluate right ventricular function following mitral valve replacement, we studied 84 patients with isolated mitral valve disease with the use of first-pass radionuclide angiography before, 1 week after, and up to 1 year after operation. The right ventricular ejection fraction for the entire group improved from 29% +/- 11% to 43% +/- 10% (p less than 0.001) at 1 week. This increase was maintained at 3 months (41% +/- 10%) and up to year after operation (40% +/- 12%). The improvement was found not to be influenced by either the type of valvular lesion or the presence and/or level of pulmonary hypertension. When the patients were grouped according to the type of prosthetic valve placed at operation, the right ventricular ejection fraction increased in all patients within 1 week of operation, with sustained improvement at 3 months postoperatively. Thereafter, it began to decline in patients receiving a Carpentier bioprosthesis while being maintained in those patients who received disc valves. Further analysis revealed that those patients who receiving the larger Carpentier bioprostheses had a greater deterioration of right ventricular function than those receiving the smaller Carpentier valves. Left ventricular function in the entire group was normal preoperatively (62% +/- 16%) and was unchanged at 1 week (60% +/- 16%) and a 1 year (59% +/- 16%) after operation.

Adult↗
PubMed1979

Tricuspid regurgitation: clinical and angiographic assessment.

Because previous attempts to diagnose and quantitate tricuspid regurgitation (TR) by angiography have been unreliable, 60 patients with mitral or combined mitral and aortic valve disease had right ventriculography using a special preshaped catheter. A clinical diagnosis of TR was confirmed in 45% of the patients with moderate and severe TR. A pansystolic murmur increasing in intensity with inspiration, a pulsatile liver, and a prominent CV wave in the jugular veins when present together were specific for severe TR but were seen in only 30% of the patients with severe TR but were seen in only 30% of the patients with severe TR (3+ or 4+). Ventricularization of the right atrial pressure contour was specific for severe TR but was seen in only 40% of the patients with severe TR. A normal right atrial mean pressure (RAP) did not exclude TR, but a rise in RAP or an unchanged RAP with deep inspiration was seen in all patients with TR. Similar findings were observed in two patients with severe pulmonary hypertension who had no TR. There was no relation between the magnitude of this rise in RAP, the degree of pulmonary hypertension, and the severity of TR. The use of a special preshaped catheter tends to avoid the induction of premature beats, and right ventriculograms with a preshaped catheter may be useful in diagnosing TR.

Blood Pressure↗