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Biomedical subjects

J M Isner

Publications and source records attributed to J M Isner.

At least 307 records · Page 17Linked to original sources
PubMed1984

Vasodilator effect on right ventricular function in congestive heart failure and pulmonary hypertension: end-systolic pressure--volume relation.

The right ventricular (RV) end-systolic pressure-volume relation during vasodilator administration was studied in 10 patients with pulmonary arterial (PA) hypertension, most of whom had biventricular failure. RV end-systolic volumes were estimated from equilibrium radionuclide RV counts and forward cardiac output. Simultaneous radionuclide and hemodynamic values were measured at rest and during nitroglycerin and nitroprusside infusion. Vasodilator administration resulted in decreases in PA mean and systolic pressures in all 10 patients, with an average decrease in end-systolic pressure (p less than 0.001) from 48 +/- 11 to 38 +/- 9 and 35 +/- 10 mm Hg during nitroglycerin and nitroprusside administration, respectively. In each patient, a direct linear relation was observed between the vasodilator-induced decrease in PA end-systolic pressure and in RV end-systolic volume. Average RV end-systolic volume decreased (p less than 0.001), from 130 +/- 69 ml/m2 at baseline to 108 +/- 62 and 102 +/- 55 ml/m2 during nitroglycerin and nitroprusside infusion, respectively. The slope of the RV end-systolic pressure-volume relation was directly related to RV ejection fraction. Thus, the vasodilator-induced decrease in PA systolic pressure is accompanied by a linear decrease in RV end-systolic volume, with a slope which is dependent on RV systolic function. This linear relation is analogous to the left ventricular end-systolic pressure-volume relation.

Adult↗
PubMed1984

Laser myoplasty for hypertrophic cardiomyopathy. In vitro experience in human postmortem hearts and in vivo experience in a canine model (transarterial) and human patient (intraoperative).

The feasibility of performing a myotomy/myectomy for hypertrophic cardiomyopathy (HC) by means of laser phototherapy was evaluated experimentally in vitro and in vivo, and the procedure then applied to a patient intraoperatively. In vitro experience revealed that the beam of an argon laser, delivered directly or via an optical fiber, could both cut and vaporize myocardium, producing a myotomy/myectomy morphologically similar to that produced by the conventional blade technique. In vivo experiments, in which the beam of an argon laser was delivered via an optical fiber to the ventricular septum of a canine heart, confirmed that a laser myoplasty could be achieved in 4 of 5 dogs by a transarterial approach. Finally, laser myoplasty was performed intraoperatively in a patient with HC, using a 200-mu fiber interfaced with an argon laser. Measured laser power was 1.5 W; cumulative exposure was less than 4 minutes; the myoplasty was 4 X 1 X 0.5 cm. These investigations establish the feasibility of using laser therapy to create a myoplasty trough that is similar in appearance to that typically achieved by the conventional blade technique. Illumination of the intraventricular operative field and precise modeling of the myoplasty trough constitute the principal advantages of laser myoplasty for HC.

Adult↗
PubMed1984

Sudden unexpected death as a result of anomalous origin of the right coronary artery from the left sinus of Valsalva.

The association of sudden unexpected death with coronary artery anomalies has been limited to cases of anomalous origin of the left main coronary artery, either from the right sinus of Valsalva or from the main pulmonary artery. In contrast, anomalies involving the origin of the right coronary artery have been considered to be benign. Postmortem examination in a patient who died suddenly at 23 years of age disclosed that the right coronary artery originated anomalously from the left sinus of Valsalva. The findings in this patient: (1) constitute the first necropsy documentation of premature sudden unexpected death in a patient whose sole pathologic abnormality was anomalous origin of the right coronary artery; (2) have important implications regarding previously proposed mechanisms of sudden death due to anomalous origin of the left main coronary artery; and (3) support recent suggestions that markedly acute angulation of either coronary artery, even when located in the appropriate sinus of Valsalva, may predispose to sudden unexpected death.

Adult↗
PubMed1984

The persistent enigma of percutaneous angioplasty.

In summary, while both the short-term and long-term success of PTCA is undeniable in most patients, the basis for this success remains an enigma. Admittedly, simply because "plaque fractures" and "dissection clefts" have been observed to occur as the result of artifact, one cannot exclude the possibility that the success of PTCA may be related to these lesions. Alternatively, the fact that improved vessel patency is frequently observed angiographically and pathologically in the absence of such lesions precludes firm assurance that such lesions are the basis for a successful dilatation. Identification of the mechanism responsible for the success of PTCA is more than a matter of simple curiosity: improved understanding of the basis for successful PTCA might lead to technical refinements in the procedure and allow one to better tailor the technique to individual variations in lesion morphology. Perhaps the combined use of selective, intra-vascular angioscopy at the time of PTCA will enhance our understanding of the fundamental mechanism responsible for this highly effective therapy.

Angioplasty, Balloon↗
PubMed1984

Combined posteroanterior subepicardial fat simulating the echocardiographic diagnosis of pericardial effusion.

The location and relative size of echo-free spaces observed by cardiac ultrasound have been considered reliable signs for distinguishing pericardial fat from fluid; spaces that are exclusively anterior have been considered to represent fat, while spaces that are exclusively or predominantly posterior have been considered to represent fluid. In the present study, the location and relative size of echo-free spaces in eight patients suggested the diagnosis of pericardial effusion; evaluation by computed tomography or thoracotomy, or both, in six and necropsy in two, however, disclosed that these echo-free spaces--posterior as well as anterior--were exclusively due to fat. Age appeared to be as important a predisposing factor as obesity in the accumulation of excess subepicardial fat. No M-mode or two-dimensional features were found to be reliable in differentiating fat from fluid, although excessive amplitude of the posterior pericardial echo on the M-mode study favored the diagnosis of fat. Thus, the finding of echo-free spaces by cardiac ultrasound, even when the posterior space is isolated or larger than an accompanying anterior space, is not necessarily indicative of pericardial fluid. In elderly patients, in particular, posterior echo-free spaces due to fat may invite an incorrect diagnosis of pericardial effusion or pericarditis. In patients in whom echo-free spaces represent an unexpected finding of cardiac ultrasound examination, computed tomography of the chest may be helpful in establishing whether they are due to fat or fluid.

Adipose Tissue↗
PubMed1984

Ergonovine provocation in post partum myocardial infarction.

Post-partum myocardial infarction is rare and the pathophysiology obscure. This report describes a 30-year-old lactating female in whom an inferolateral wall myocardial infarction was documented 5 months following a normal pregnancy and delivery. Coronary angiography revealed normal coronary arteries, a finding described previously in 3 such patients. Contrary to previous speculations, however, provocative testing with ergonovine produced no evidence of coronary artery spasm.

Adult↗
PubMed1984

Computed tomographic examination of the heart.

Computed tomography (CT) has been demonstrated to be a valuable means of noninvasively imaging the cardiovascular system. In particular, necropsy studies and analysis of surgically excised specimens have indicated that CT represents the premier technique for measurement of pericardial thickness and a valuable adjunct in the diagnosis and staging of cardiac neoplasms. Although careful pathologic analysis has shown CT to be an accurate means of assessing the extent of experimental myocardial infarction, logistic considerations have thus far limited the routine use of CT in clinical practice. A variety of additional cardiovascular applications of CT, including evaluation of bypass graft patency, aortic dissection, and intracavitary thrombus, are currently under investigation.

Adipose Tissue↗
PubMed1984

Coronary angiographic and morphologic correlation.

Necropsy and, more recently, physiologic studies have demonstrated the limitations of coronary angiography in estimating the percentage of luminal narrowing due to atherosclerotic plaque. Necropsy studies have also confirmed that coronary arterial spasm is typically associated with fixed atherosclerotic stenoses. Finally, necropsy studies of individual patients have clarified certain points regarding thrombolytic therapy, coronary "collateral" blood flow, myocardial bridges, and coronary arterial dissection.

Aortic Dissection↗
PubMed1983

Permanent pacemaker therapy in corrected transposition of the great arteries: analysis of site of lead placement in 40 patients.

A retrospective analysis of 58 pacemaker leads in 40 patients with corrected transposition of the great arteries (CTGA) was made to compare the function of endocardial and epicardial leads. Extensive trabeculations of the normal right ventricle are generally thought to be essential for endocardial pacemaker lead stability. Because the systemic venous ventricle in CTGA lacks an extensive trabecular network, there has been concern that transvenous lead placement may result in a high rate of dislodgement. Epicardial leads have been assumed to be more reliable in these patients. Forty-seven epicardial and 11 endocardial leads were placed in 40 patients with CTGA who required permanent pacemaker therapy for symptomatic bradycardia. Of 13 episodes of epicardial lead malfunction in 158 patient-years, 3 were due to lead fracture and 10 to high thresholds. Surgery was required to correct the lead malfunction in 12 instances and thoracotomy was necessary for new lead placement in 6 patients. During 26.2 patient-years, there were 2 episodes of endocardial lead failure due to a high acute threshold and perforation. There were no instances of endocardial lead dislodgement. No association between type of failure and lead design was noted for either endocardial or epicardial leads. Actuarial analysis of survival revealed no significant differences in reliability between endocardial and epicardial leads. Endocardial lead fixation in the systemic venous ventricle in patients with CTGA is adequate to prevent lead dislodgement and preferable to epicardial lead placement because thoracotomy is avoided.

Adolescent↗
PubMed1983

Frequency in nonangioplasty patients of morphologic findings reported in coronary arteries treated with transluminal angioplasty.

The coronary arteries from 70 consecutive patients in whom percutaneous transluminal angioplasty (PTA) had not been performed during life were examined at necropsy for findings that have been previously described in patients or animals treated with PTA. In 33 (49%) of the 70 patients, 1 or more findings identical to those observed in necropsy studies of PTA-treated arteries were observed: "plaque fractures" in 31 (44%), "dissection clefts" in 26 (33%), and extensive medial thinning in 40 (57%). Observations in these 70 patients indicate that findings previously described in PTA-treated patients cannot necessarily be assumed to represent the results of PTA. The fact that improved vessel patency may be seen in the absence as well as the presence of such lesions precludes firm assurance that such lesions are the sole basis for successful angioplasty.

Angioplasty, Balloon↗
PubMed1983

Catheter fragmentation: a potential source of catheter embolus.

Aortic root angiography in the patient described in the present report was complicated by precipitious catheter occlusion. Analysis of the occluding fragment by infrared spectroscopy indicated that it was a urethane structure, suggesting that the occluding fragment resulted from spontaneous fragmentation of the polyurethane catheter. Experience with this patient thus documents the potential for nonblood catheter embolus.

Cardiac Catheterization↗
PubMed1983

Clinical and morphologic cardiac findings after anthracycline chemotherapy. Analysis of 64 patients studied at necropsy.

The relation between clinical evidence of and histologic signs of anthracycline cardiotoxicity was evaluated by reviewing the clinical and morphologic findings in 64 patients studied at necropsy, all of whom had received doxorubicin or daunorubicin chemotherapy during life. Of the 64 patients, 20 (31%) had documented clinical toxicity consisting of impaired left ventricular systolic performance; in 7 (35%) of these 20 patients, histologic signs of toxicity were absent. In the remaining 13 patients with clinical toxicity, histologic signs of toxicity ranged from mild to severe. Of the 44 (69%) patients without clinical signs of drug toxicity, 21 (48%) had no histologic sign of cardiotoxicity; in 23 (52%) of the patients without clinical toxicity, however, morphologic signs of cardiotoxicity were nevertheless present--mild in most patients, but extensive in 4. Signs of extensive histologic toxicity (19 [30%] of 64 patients) were associated with large doses (greater than 450 mg/m2) of the drug, mediastinal irradiation, and age greater than 70 years. This study suggests that attempts to monitor cardiotoxicity by serial evaluation of cardiac histology in patients undergoing anthracycline chemotherapy may be seriously limited by the fact that clinical evidence of toxicity may be present without histologic signs of toxicity; likewise, histologic signs of anthracycline toxicity may be present without clinical evidence of toxicity.

Adolescent↗
PubMed1983

Subepicardial adipose tissue producing echocardiographic appearance of pericardial effusion. Documentation by computed tomography and necropsy.

An isolated anterior echo-free space is generally regarded as a false-positive echocardiographic finding for pericardial effusion. Even when an anterior echo-free space is accompanied by a posterior echo-free space, the echo-free spaces have been occasionally reported to be falsely positive for pericardial effusion, principally in patients with cardiac neoplasms. The basis for these findings had never been adequately explained. In the present study, evaluation by computed tomographic imaging or necropsy examination of 5 patients in whom there was either an anterior or posterior echo-free space or both demonstrated that subepicardial adipose tissue is the echocardiographic imitator of pericardial effusion.

Adipose Tissue↗
PubMed1982

Primary versus secondary mitral valve prolapse: clinical features and implications.

This study considers the implications that two types of mitral valve prolapse exist. One is primary, and consists of a basic abnormality of the mitral apparatus. While the etiology of this lesion may not always be the same, the major gross abnormalities are usually constant. Secondary mitral valve prolapse generally exists merely as a consequence of reduced or abnormal ventricular dimensions, and usually appears to be a benign phenomenon.

Anorexia Nervosa↗