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Biomedical subjects

A Chaux

Publications and source records attributed to A Chaux.

At least 73 records · Page 4Linked to original sources
PubMed1984

Detection of occult pericardial hemorrhage early after open-heart surgery using technetium-99m red blood cell radionuclide ventriculography.

Pericardial or mediastinal hemorrhage requiring reoperation occurs in 2% to 5% of patients, usually early (0 to 48 hours), after open-heart surgery. This hemorrhage may be occult, and resulting cardiac tamponade may easily be misinterpreted as ventricular dysfunction, common early postoperatively. In such cases, appropriate and timely intervention may not occur. Of 50 patients evaluated by technetium-99m red blood cell gated equilibrium radionuclide ventriculography (RNV) because of early postoperative cardiogenic shock of uncertain etiology, 17 had unique scintigraphic images suggestive of intrathoracic hemorrhage. Of these 17, 5 had a generalized "halo" of abnormal radioactivity surrounding small hyperdynamic right and left ventricles, 11 had localized regions of intense blood pool activity outside the cardiac chambers (two with compression of single chambers), and one demonstrated marked radionuclide activity in the right hemithorax (2000 ml of blood at reoperation). Twelve patients had exploratory reoperation for control of hemorrhage as a direct result of the scintigraphic findings, three were successfully treated with fresh frozen plasma and platelet infusions along with medical interventions to optimize cardiac performance, and two patients died in cardiogenic shock (presumed tamponade) without reoperation. In the 12 reoperated patients, all were confirmed to have active pericardial bleeding. Scintigraphic localization of abnormal blood pools within the pericardium corresponded to the sites at which active bleeding was witnessed at reoperation. The abnormal bleeding was etiologically related to the tamponade state, with marked improvement in hemodynamics after reoperation. Nine additional patients were reoperated for presumed tamponade after RNV revealed an exaggerated halo of photon deficiency surrounding the cardiac chambers.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Surgical Procedures↗
PubMed1984

Bileaflet, tilting disc and porcine aortic valve substitutes: in vitro hydrodynamic characteristics.

The desire for a low profile mechanical valve with better fluid dynamic performance led to the design and development of the St. Jude Medical bileaflet prosthesis. Comparative in vitro flow studies indicate that it has better pressure drop characteristics than the Björk-Shiley (convexo-concave) and Carpentier-Edwards porcine valves in current clinical use, especially in the small sizes. In the 21 to 27 mm aortic valve size range the St. Jude valve has an average performance index of 0.66, compared with 0.46 and 0.32 for the Björk-Shiley and Carpentier-Edwards valves, respectively. In contrast, the St. Jude valve has larger regurgitant volumes than both the Björk-Shiley and Carpentier-Edwards valves. Velocity measurements with a laser-Doppler anemometer indicate relatively centralized flow with small amounts of turbulence downstream of the St. Jude valve. The flow is unevenly distributed between the central and side orifices. The turbulent shear stresses are, however, large enough to cause sublethal or lethal damage to blood elements. Wall shear stresses are smaller than those measured downstream of the Björk-Shiley valve. Regions of flow separation were observed just downstream from the sewing ring, which could lead to excess tissue growth along the sewing ring. The results of this study indicate that overall in vitro fluid dynamic performance of the St. Jude valve is superior to that of the two other commonly used prostheses.

Animals↗
PubMed1984

Bileaflet, tilting disc and porcine aortic valve substitutes: in vivo hydrodynamic characteristics.

The St. Jude valve is a new bileaflet disc cardiac valve prosthesis designed to avoid some of the hemodynamic drawbacks of other prostheses. The in vivo flow characteristics of the St. Jude aortic valve (42 patients) were studied and compared with those of three other commonly used aortic prostheses. Björk-Shiley (12 patients), Hancock (27 patients) and Carpentier-Edwards (15 patients). The studies, performed 24 to 48 hours after surgery, included measurements at rest and during augmentation of valve flow by infusion of isoproterenol. The mean performance index for valves of all sizes is higher for the St. Jude than for either porcine valve, both at rest and during isoproterenol infusion (p less than 0.05). Utilizing data both at rest and with isoproterenol, the relation of valve flow and mean systolic gradient for each size of St. Jude valve (19 to 25 mm) indicates the occurrence of small increases in gradient (5.3 to 8.2 mm Hg) as valve flow increases, ranging from 161 to 436 ml/systolic X min. A direct comparison of valve flow and gradient data for all size 25 and 23 mm prostheses at rest indicates a tendency for a lower mean systolic gradient in both mechanical valves than in either porcine valve (p = 0.07). With isoproterenol augmentation of valve flow in 25 mm valves, the gradient is less (p less than 0.05), and the effective orifice area and performance index are larger (p less than 0.05) for the St. Jude than for either porcine valve.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

The St. Jude Medical bileaflet valve prosthesis. A 5 year experience.

A 5 year experience with the bileaflet St. Jude Medical valve is reported. Between March, 1978, and June, 1982, 198 patients received 233 such valves (90 mitral, 73 aortic, and 35 double mitral-aortic valve replacements). Total follow-up was 4,896 patient-months; survivors were followed up for 1 to 5 years (mean 35 months). Early (30 day) mortality was 6.6% overall and 11.1% after mitral, 2.7% after aortic, and 2.9% after double valve replacement. Total late mortality was 15.2%; the actuarial survival rate at 4 years was 67% after mitral, 79% after aortic, and 79% after double valve replacement. Ischemic mitral valve disease was associated with an early mortality of 26.7% and a 4 year survival rate of 34%; without this high-risk subset, early mortality was 3.3% and the 4 year survival rate was 77% after mitral valve replacement. A multivariate logistic regression model identified three preoperative patient characteristics associated with increased postoperative mortality: ischemic mitral valve disease (p less than 0.001), a depressed left ventricular ejection fraction (less than 55%; p less than 0.05), and advanced New York Heart Association class (IV; p less than 0.05). Valve-related complications occurred in 14 patients (3.4% per patient-year). There were no instances of primary structural failure or hemolysis. Thromboembolism (nine patients, 2.2% per patient-year) occurred more frequently after double (3.7% per patient-year) or mitral valve replacement (2.3% per patient-year) than after aortic valve replacement (1.3% per patient-year) and more frequently in 12 patients receiving aspirin and dipyridamole (6.5% per patient-year) than in 173 patients receiving warfarin (1.9% per patient-year). No thromboembolic event was fatal. Reoperation was necessary because of one valve thrombosis, one valve erosion, and two perivalvular leaks due to endocarditis; three of the four patients survived reoperation (one valve-related death, 0.5%). Of 154 patients alive at latest follow-up, 85% were in New York Heart Association Class I or II, and 90% had improved by at least one class. This intermediate experience with the St. Jude Medical valve indicates that, in addition to its previously demonstrated excellent hemodynamic performance, there have been no instances of primary structural failure or hemolysis. Warfarin anticoagulation is recommended in all patients.

Adolescent↗
PubMed1984

Mitral valve replacement: impact of coronary artery disease and determinants of prognosis after revascularization.

From 1969 to 1982, 419 patients underwent single mitral valve replacement; of these, 48% had associated coronary artery disease (9% single vessel, 8% double vessel, 28% triple vessel, 3% left main). In 216 patients with no associated coronary disease, in 179 patients with coronary disease that was revascularized, and in 24 patients with coronary disease that was not revascularized, the 30 day mortalities were 4.2%, 13.9%, and 29.2% (p less than .05) after valve replacement. Actuarial survivals at 8 years were 68%, 44%, and 15%, respectively (p less than .01), with 1 to 165 months of follow-up (mean 52). After matching the three cohorts of patients in age, sex, left ventricular ejection fraction, and valve lesion, the presence of associated coronary artery disease decreased long-term survival and revascularization improved survival (p less than .05 for both). Incidental coronary disease in patients with rheumatic mitral valve disease had a significant negative influence on survival if left unbypassed (p less than .05); after revascularization and valve replacement, the 30 day mortality was 7.3% and the 8 year survival was 52%. Coronary disease etiologically related to ischemic mitral regurgitation identified a high-risk group of patients, with a 30 day mortality of 19.6% and an 8 year survival of 37% after the combined procedure. A multivariate logistic regression model was used to determine which preoperative and intraoperative variables predicted early and late outcome after combined mitral valve replacement and coronary revascularization. Predictors of early death were advanced age (greater than 60 years), New York Heart Association functional class (IV), an ischemic etiology of the mitral valve disease, and a depressed left ventricular ejection fraction (less than 55%). Predictors of late death were triple-vessel or left main coronary disease, increased left ventricular end-diastolic volume (greater than 120 ml/m2), and depressed left ventricular ejection fraction (less than 55%). These findings highlight the important etiologic and prognostic role of coronary artery disease in patients requiring mitral valve replacement.

Adolescent↗
PubMed1983

Noninvasive detection of active pericardial bleeding using cardiac blood pool scintigraphy.

The diagnosis of active pericardial bleeding has traditionally depended on an invasive documentation by needle aspiration, angiography, or direct inspection. Blood pool scintigraphy performed in 2 patients just before and after the development of hemopericardium revealed unique images in which acute pericardial bleeding manifested itself by an additional blood pool adjacent to the cardiac chambers. With appropriate attention to technical factors, such distinctive images should be highly specific for active bleeding into the pericardial sac.

Aged↗
PubMed1983

Coronary artery stenoses. Relationship between angiographic severity and impact on mean diastolic pressure gradient.

Coronary angiography provides important anatomic information about coronary artery stenoses. However, it is unclear whether specific assumptions about hemodynamic impact can be made from the angiogram. We therefore studied the relationship between angiographic severity of coronary stenoses and the mean diastolic pressure gradient measured directly at coronary bypass operation. We studied 29 stenoses selected because they were the only lesions in a given vessel, they were well seen in two angiographic views, and there was no change in clinical status of the patient between angiographic and surgical procedures. Fourteen stenoses were in the left anterior descending artery, nine were in the right coronary artery, and six were in the left circumflex artery. Correlation between mean diastolic gradient and percent stenosis was good (r = 0.78, p = 0.001) and especially so for lesions in the left anterior descending artery (r = 0.84, p = 0.001). Lesions over 90% had a wide range of gradients, while lesions less than 90% tended to have more predictable gradients. Collaterals invariably identified vessels with stenoses causing major pressure gradients. History of myocardial infarction was associated with major gradients in supplying vessels. Length of stenosis was not an important influence on gradient over a stenosis. We conclude that in some defined instances, generalizations about hemodynamic (and presumed functional) impact of stenoses can be made from the angiographic assessment, but precise assumptions are not possible.

Adult↗
PubMed1983

Arrhythmias and conduction disturbances following cardiac operation for the removal of left atrial myxomas.

Between September, 1971, and April, 1982, 11 patients (seven female) with left atrial myxomas underwent surgical resection at Cedars-Sinai Medical Center. The tumors ranged in size from 4 to 9 cm (mean 6.3 cm) and were attached to the interatrial septum (four superiorly, four inferiorly), the free atrial wall (one posteriorly, one at the dome), or both (one). Although all patients were symptomatic preoperatively, arrhythmias were uncommon; only one had chronic atrial fibrillation, and two others had had single episodes of paroxysmal atrial fibrillation in the immediate preoperative period. Early postoperatively, all but one patient had episodes of atrial fibrillation (eight patients), atrial flutter (four patients), junctional rhythm (six patients), sinus arrest (two patients), or complete heart block (three patients). Ten patients required antiarrhythmic therapy, and two required permanent pacemaker implantation. After a mean follow-up of 48 months (range 7 to 124), seven patients continue to have episodic or chronic supraventricular arrhythmias, with only three patients not using antiarrhythmic drugs regularly. The pathophysiological basis for these arrhythmias is unclear, but some patients appear to have sustained injury to the sinus node or atrioventricular node, while others have developed interatrial or intra-atrial conduction delays. Attention should be directed to the basis of these arrhythmias and conduction disturbances, as surgical technique may be the major determinant of this early and late postoperative complication.

Adult↗
PubMed1983

Post-myocardial infarction ventricular septal defect. Improved outlook.

Eight patients (mean age 63.75 years) were operated upon for post-myocardial infarction ventricular septal rupture (PMI-VSD) within 1 to 21 days of the infarction and 8 hours to 18 days of rupture. All but one were in low cardiac output syndrome necessitating intra-aortic balloon pumping; all had cardiac catheterization. The VSD was closed via a transinfarct ventriculotomy with an oversized folded double patch, the folded edge being incorporated in the ventriculotomy closure. Five patients received seven saphenous vein coronary bypass grafts. None had recurrent shunts. Six patients (anterior VSD, five; posterior VSD, one) are survivors (18 months to 2.5 years) in Class I (five) or Class II (one). Two patients died postoperatively, one (anterior VSD) of an arrhythmia and the other (posterior VSD) while on biventricular bypass support. Two survivors in whom prolonged preoperative stabilization was attempted required emergency operation before the planned waiting period of 3 weeks had elapsed, and both had postoperative multiorgan complications. Our present approach is to operate as soon as clinical and catheterization diagnosis of VSD is made.

Aged↗
PubMed1983

Transient hemodynamic dysfunction after myocardial revascularization. Temperature dependence.

We studied hemodynamics and the effects of right atrial pacing (110 beats/min) following complete myocardial revascularization and hypothermic multidose potassium crystalloid cardioplegia in 12 patients with a normal preoperative left ventricular ejection fraction (LVEF). Measurements were made immediately preoperatively, postoperatively at specified temperatures during the rewarming period (90 degrees F, 94 degrees F, and 98 degrees F), and at 24 hours. No patient had a perioperative myocardial infarction. At 90 degrees F, hemodynamics were characterized by significant decreases in cardiac index, stroke volume index, and left ventricular stroke work index (LVSW) and an increase in systemic vascular resistance index (SVRI) compared to preoperative values (p less than 0.05). Right atrial pacing significantly increased cardiac index preoperatively and 24 hours postoperatively, but not during the rewarming period. Over the entire rewarming period (90 degrees F to 98 degrees F), each of the following variables correlated with temperature: cardiac index (r = 0.71 in sinus rhythm and r = 0.66 with right atrial pacing); stroke volume index (r = 0.33 and 0.66); SVRI (r = -0.80 and -0.64); LVSW (r = 0.37 and 0.73); and heart rate in sinus rhythm (r = 0.51). During the rewarming period, there was an inverse relationship between cardiac index and SVRI (r = -0.87). In conclusion, after myocardial revascularization: (1) transient hemodynamic dysfunction occurs during the rewarming period (90 degrees F to 98 degrees F); (2) this dysfunction is temperature-dependent; and (3) right atrial pacing at 110 beats/min does not improve hemodynamic function during the rewarming period. Temperature must be considered in the evaluation of left ventricular and hemodynamic function following myocardial revascularization.

Adult↗
PubMed1982

Flow characteristics of the St. Jude prosthetic valve: an in vitro and in vivo study.

The St. Jude cardiac prosthetic aortic valve was evaluated in vitro and in vivo in an attempt to establish flow characteristics and to correlate them with clinical findings. In vitro, a fluid vehicle (6% Polyol V-10, 32 degrees C) with viscosity similar to blood (0.035 dyne-sec/cm2) was used under conditions of steady flow through a flow chamber simulating the aortic root. Gradient, velocity, and shear stress were measured 5.79 mm, 26.79 mm, 44.79 mm, and 77.79 mm downstream from 25-mm and 27-mm valves using a laser-Doppler anemometer. At 417 ml/sec, the valve gradient was 6.2 mmHg with the 25-mm valve, and 5.2 mmHg with the 27-mm prosthesis. Velocity was maximum at the orifice center, and wall shear stress was low (maximum 600 dyne/cm2). In vivo, six patients with 25-mm St. Jude aortic valves were studied within 48 hours after surgery to determine cardiac output, valve flow, and gradient. The gradient was 3.3 +/- 1.9 mmHg (M +/- SD) at 249 +/- 96 ml/sec and the effective valve area was as large as the geometric area (2.58 vs. 3.09 cm2). Thus, flow through the St. Jude valve is unobstructed and central, has low turbulence, and achieves optimal effective valve area for a given available orifice area.

Aortic Valve↗
PubMed1982

Right atrial tamponade complicating cardiac operation: clinical, hemodynamic, and scintigraphic correlates.

Persistent bleeding into the pericardial space in the early hours after cardiac operation not uncommonly results in cardiac tamponade. Single chamber tamponade also might be expected, since in this setting the pericardium frequently contains firm blood clots localized to the area of active bleeding. However, this complication has received very little attention in the surgical literature. We are therefore providing documentation that isolated right atrial tamponade can occur as a complication of cardiac operation and that there exists a potential for misdiagnosis and hence incorrect treatment of this condition. Right atrial tamponade may be recognized by a combination of low cardiac output, low blood pressure, prominent neck veins, right atrial pressure in excess of pulmonary capillary wedge pressure and right ventricular end-diastolic pressure, and a poor response to plasma volume expansion. Findings on chest roentgenogram and gated wall motion scintigraphy may be highly suggestive. This review should serve to increase awareness of this complication and to provide some helpful diagnostic clues.

Bioprosthesis↗
PubMed1981

An appreciation of the new St. Jude valvular prosthesis.

Beginning in March, 1978, 88 patients have had cardiac valve replacements with St. Jude prostheses. There were 26 males and 62 females, aged 6 to 80 years (mean 60). Single valve replacement was done in 67. Double valve replacement was done in 21; 12 of them had two St. Jude valves and nine had a different second valve. There were 57 mitral and 43 aortic valves replaced. Thirty-six patients had concomitant aorta-coronary bypass, and six others had additional cardiac procedures. All patients have been followed for a total of 807 patient-months (mean 9 months). Seventy-nine have been receiving sodium warfarin and seven are not receiving anticoagulants. There has been one embolic episode. There are no valve failures to date. Early mortality is 2.3% and late mortality, 5.7%; no death was valve related. Fifty-three survivors have improved by two or more N.Y.H.A. classifications. Fifty-four valves studied postoperatively at rest, during pacing, and during isoproterenol infusion have demonstrated significantly better hemodynamic performance than have mitral porcine xenografts studied in an identical manner (p < 0.05). Phonocardiography, M-mode and two-dimensional echocardiography, and cinefluoroscopy, carried out in 18 patients, have proved to be reliable noninvasive techniques for long-term follow-up. This experience indicates that the St. Jude prosthesis offers an excellent and predictable alternative in the surgeon's decision-making concerning valve choices.

Adolescent↗
PubMed1980

Unusual complications of endocardial pacing.

This report concerns two unusual complications of endocardial pacing: (1) simultaneous thrombosis of the superior and inferior venae cavae and (2) supravalvular, valvular, and infravalvular stenosis of the tricuspid valve. The management of both cases required removal of all endocardial leads with the aid of cardiopulmonary bypass, with inferior vena cava thrombectomy in the first case and tricuspid valve replacement in the second. From our review of the literature, we have reached the following conclusions: (1) Clinical thrombosis secondary to endocardial pacing leads is rare (1.2%), but venography in asymptomatic patients revealed venous thrombosis in 44% of the patients studied. (2) Endocardial pacing leads should have the smallest outer diameter possible, preferably with an electro-negative, thromboresistant surface, and should be implanted with minimal redundancy. The risk of venous thrombosis should be kept in mind when recommending atrioventricular sequential pacing systems requiring multiple leads passing through the superior vena cava. (3) Retained leads which are infected or have migrated and become redundant or looped are at risk of causing septicemia, thrombosis, or septic embolization and should be removed. The high incidence of subclinical venous thrombosis suggests that reasonable efforts be made to remove all retained leads.

Aged↗