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Biomedical subjects

I Kronzon

Publications and source records attributed to I Kronzon.

At least 127 records · Page 7Linked to original sources
PubMed1994

Transesophageal echocardiography in pericardial disease and tamponade.

While most pericardial disorders can be imaged by transthoracic echocardiography, transesophageal echocardiography may be required in those cases where pericardial pathology is clinically suspected, but cannot be imaged adequately with transthoracic echocardiography. Transesophageal echocardiography is especially helpful in patients after heart or chest surgery, with cardiac compression by a loculated pericardial hematoma, in patients with dissection, endocarditis, or interatrial shunting associated with pericardial effusion, in patients with pericardial tumors, and in the differential diagnosis between constrictive pericarditis and restrictive cardiomyopathy.

Cardiac Tamponade↗
PubMed1993

Protruding atheromas in the thoracic aorta: a newly recognized source of cerebral and systemic embolization.

Up to 40% of stroke patients do not have an obvious etiology for their illness. Because transthoracic echocardiography is often negative in these patients, there has been increasing enthusiasm for transesophageal echocardiography (TEE) as a newer tool for evaluating patients with embolic disease. In a study of patients referred because of unexplained stroke or transient ischemic attacks, the most common finding was protruding atheroma in the aortic arch. In a case control study, protruding aortic atheromas were found in 33 of the 122 patients with emboli (27%). Mobile components to the atheromas were found in 11 case patients, and there were no mobile components found in any control patients. It is also possible that protruding aortic atheromas may play a role in patients with other sources of emboli (e.g., carotid disease). Atheromas may also cause emboli during catheterization, balloon pump placement, and cardiopulmonary bypass. The pathological composition of the lesions seen on TEE has been atheroma with superimposed thrombus. The correct treatment for patients with embolization due to protruding aortic atheromas has not yet been determined, although anticoagulation may play a role, since the mobile components to these lesions appear to be thrombus. We have recommended surgery for several patients. However, the operation is a major one with major potential complications, including aortic dissection. TEE should be done in patients with unexplained emboli, and it may also play a role in patients with other sources of embolization. TEE should be considered in elderly patients or those with extensive vascular disease before cardiac catheterization or heart surgery. In addition, cannulation techniques during bypass can be modified to avoid atheromas. The ideal medical and/or surgical approaches to patients with protruding atheromas remain to be clarified.

Angioplasty, Balloon, Coronary↗
PubMed1993

Electrocardiographic changes during cesarean section: a cause for concern?

A Holter monitor was used to record ST segment changes during cesarean section in 170 consecutive healthy parturients starting 2 h before and ending 3 h after surgery. Lumbar epidural anesthesia (LEA, n = 120) or subarachnoid anesthesia (SA, n = 50) was used. Transthoracic 2-D echocardiograms were obtained in 30 patients from the LEA group. ST depression or elevation occurred 160 times in 44 patients from both groups. Ninety-eight percent of these changes occurred between induction of anesthesia and the end of surgery, with 78% of the episodes registering -1 mV. In the LEA group, the number of episodes tended to increase after delivery, but in the SA group, the frequency remained constant. ST segment depression was recorded in 38% and 14% of patients in the LEA and SA groups, respectively (P < 0.05, x2 analysis). No wall motion abnormality was noted in the echocardiogram during ST segment depression. Neither the 12-lead electrocardiogram nor plasma myocardial specific creatine kinase suggested myocardial damage. The operative events, alone or in combination, including hypertension, tachycardia, hypotension, bradycardia, air embolism (precordial Doppler) were neither specific nor sensitive as predictors of ST segment change (stepwise logistic regression). Tachycardia was associated with ST segment changes in 10% of time epochs (5 min) (P = 0.05, x2 analysis). Thus, ST segment changes during cesarean section are not caused by myocardial ischemia and are not of any clinical consequence.

Adult↗
PubMed1992

Observations of coronary flow augmentation and balloon function during intraaortic balloon counterpulsation using transesophageal echocardiography.

The intraaortic balloon pump has been shown to decrease myocardial oxygen demand by afterload reduction, while increasing myocardial oxygen supply by diastolic augmentation of coronary blood flow. This diastolic augmentation of coronary flow has been demonstrated experimentally with invasive methods. Noninvasively, transesophageal echocardiography has demonstrated efficacy in enabling visualization of the proximal left coronary artery and in recording coronary blood flow velocity. To assess the potential of this technique in demonstrating quantitatively the increase in coronary flow during counterpulsation, 6 patients were studied during intermittent balloon pumping. Peak diastolic coronary blood flow velocity increased by a mean of 117% (range 62 to 287) during balloon inflation (p = 0.002). Furthermore, coronary flow velocity integral increased by a mean of 87% (range 43 to 176; p = 0.003). Problems associated with intraaortic balloon pumping were discovered by transesophageal echocardiography in 4 patients (incorrect balloon placement, damage to the aortic wall [2 patients], and premature balloon deflation time). Transesophageal echocardiography can be used in evaluating intraaortic balloon positioning within the aorta and in monitoring coronary artery flow augmentation during counterpulsation. This relatively noninvasive technique adds another dimension to the evaluation of balloon function and may help in optimizing the benefits of counterpulsation.

Aged↗
PubMed1992

Surgical implications of transesophageal echocardiography to grade the atheromatous aortic arch.

Stroke is an especially serious complication of cardiopulmonary bypass with an incidence of 2% to 5%. This prospective study used transesophageal echocardiography (TEE) in 97 patients more than 65 years of age (mean age, 73 years) to identify those at high risk for aortic atheroemboli. The atheromatous disease of the aorta was graded by TEE: grade I = minimal intimal thickening (n = 29); II = extensive intimal thickening (n = 33); III = sessile atheroma (n = 15); IV = protruding atheroma (n = 10); V = mobile atheroma (n = 10). Clinical evaluation was also performed by intraoperative aortic palpation. Four patients who were graded as having normal aortas by palpation had intraoperative strokes. In contrast, 3 of these 4 patients were in grade V on TEE. The relationship of TEE to incidence of stroke was statistically significant (p less than 0.006), whereas there was no significant correlation between clinical grade and stroke incidence. Four of 10 TEE grade V patients were treated with hypothermic circulatory arrest and aortic arch debridement, and none suffered strokes. The other 6 patients were treated with standard techniques, and 3 had strokes. These results suggest that patients with mobile atheromatous disease are at high risk for embolic strokes that are not predicted by routine clinical evaluation. Selective use of circulatory arrest in the presence of TEE-detected mobile arch atheromas may reduce the risk of intraoperative stroke.

Aged↗
PubMed1992

Protruding aortic atheromas predict stroke in elderly patients undergoing cardiopulmonary bypass: experience with intraoperative transesophageal echocardiography.

Protruding atheromas of the aortic arch identified by transesophageal echocardiography have been implicated as a cause of stroke in elderly patients. One hundred thirty patients greater than or equal to 65 years of age were studied with intraoperative transesophageal echocardiography to detect aortic arch protruding atheromas and determine if these patients were at higher risk for perioperative stroke. Protruding atheromas were identified in 23 (18%) of 130 patients. In 19 (83%) of these 23 patients, palpation of the aortic arch at operation did not identify significant abnormalities. Five patients (4%) had perioperative stroke. Logistic regression identified aortic arch atheroma as the only historical or procedural variable that was predictive of stroke (odds ratio 5.8, 95% confidence interval 1.2 to 27.9, p less than 0.03). A history of peripheral or cerebrovascular disease, presence of aortic calcification, cardiac risk factors, age and duration of cardiopulmonary bypass did not predict stroke. In contrast, patients with protruding atheromas with mobile components were at highest risk. There were 3 (25%) of 12 patients with a mobile atheroma who had a stroke versus 2 (2%) of 118 patients without a mobile atheroma (chi-square = 10.3, p = 0.001). Displacement and detachment of the frail, protruding atherosclerotic material by aortic arch cannulation or by the high pressure jet emanating from the cannula tip may play an important role in the creation of embolization and stroke.

Aged↗
PubMed1992

The improved yield of transesophageal echocardiography over transthoracic echocardiography in patients with neurological events is largely due to the detection of aortic protruding atheromas.

It is important to determine what, if any, the added contribution of transesophageal echocardiography is to the evaluation of patients with unexplained strokes and transient ischemic attacks. Transesophageal echocardiography was performed in 283 consecutive patients over an 8-month period. The reason for referral in 63 of these patients was unexplained stroke or transient ischemic attack. These 63 studies were evaluated for the presence of lesions that could be etiologic in these patients, including protruding aortic atheromas, spontaneous echo contrast, atrial septal aneurysms, and atrial clots. The transesophageal and transthoracic techniques were compared. The main finding was that there were 23 abnormal findings that might have been responsible for stroke or transient ischemic attacks seen on transesophageal echocardiography, which were not visualized on transthoracic echocardiography. Transthoracic echocardiography was false negative in 19 (30%) of 63 patients. None of the protruding aortic arch atheromas seen on transesophageal echocardiography were diagnosed with transthoracic echocardiography. Transesophageal echocardiography is indicated in the evaluation of patients with unexplained strokes and transient ischemic attacks, and the added yield of this technique is largely due to the finding of protruding aortic arch atheromas.

Aorta, Thoracic↗