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Biomedical subjects

L L Michaelis

Publications and source records attributed to L L Michaelis.

At least 55 records · Page 3Linked to original sources
PubMed1982

Extended endocardial resection for the treatment of ventricular tachycardia and ventricular fibrillation.

A total of 40 patients with drug-refractory, life-threatening cardiac rhythm disturbances--ventricular tachycardia in 23 patients and ventricular fibrillation in 17 patients--underwent extended endocardial resection (EER) of scar tissue. Scarring was due to myocardial infarction in 38 patients, to previous congenital heart operation in 1 patient, and to sarcoidosis of the heart in 1. The EER procedure was directed by epicardial and endocardial mapping data whenever possible, and was usually combined with revascularization, aneurysmectomy, or, in 5 patients, mitral valve replacement. Operative mortality was 10%, incident to poor preoperative ventricular function and hemorrhage secondary to previous cardiac surgical procedures. Thirty-three of the 36 survivors (92%) are free of arrhythmia at follow-up periods ranging from 3 to 36 months (mean, 12.5 months); the arrhythmia in the remaining 3 patients is now drug controlled. Thirty-three patients had postoperative electrophysiological studies, and in 30 (91%), the arrhythmia was no longer inducible. The results of surgical treatment for ventricular tachycardia and ventricular fibrillation were similar. The results also proved satisfactory whether the EER procedure was directed by visual observation or mapping.

Adolescent↗
PubMed1981

Nonrandomized matched pair analysis of intermittent ischemic arrest versus potassium crystalloid cardioplegia during myocardial revascularization.

The quest for the ideal method of myocardial preservation during coronary artery bypass graft (CABG) surgery continues at a rapid pace. Nevertheless, in the present clinical practice of cardiac surgery, the choice is chiefly between hypothermic intermittent ischemic arrest and hypothermic potassium cardioplegia. This study applies newer technics in radionuclear cardiology, as well as more conventional enzymatic, electrocardiographic, and hemodynamic determinations, to the evaluation of the effectiveness of the previously mentioned modes of myocardial protection. Serial assessments are made preoperatively as well as during the first ten days postoperatively. We find that the perioperative incidence of myocardial damage and changes in left ventricular performance are almost identical using either method in patients with relatively normal preoperative left ventricular performance who do not have severe preoperative refractory ischemia or necrosis.

Aged↗
PubMed1981

Accuracy in coronary graft flow measurement.

A blood flow calibration apparatus is described for use with electromagnetic flow probes. It is an automatic gravity-flow system, which provides a constant level and therefore constant flow at any preset rate. On several occasions, the use of this device has helped to determine whether flow probes require simple adjustment, factory repair, or replacement. Using this system, a systematic error in the manufacturer's "precalibration" averaging +22% (range, 9 to 50%) has been discovered, and appropriate corrections have been made. The accuracy of these corrections has been confirmed by a rapid, in vivo method of calibration, which also is described and which can be carried out during the conduct of aortocoronary bypass operation. It is recommended that all groups measuring coronary graft flow become familiar with their electromagnetic flowmeter and probes by means such as those described, in the interest of accurate flow measurement after bypass operation.

Blood Flow Velocity↗
PubMed1981

Serial assessment of left ventricular performance following coronary artery bypass grafting. Early postoperative results with myocardial protection afforded by multidose hypothermic potassium crystalloid cardioplegia.

Forty patients who recently underwent coronary artery bypass graft (CABG) operations had serial hemodynamic and scintigraphic studies. Multidose hypothermic potassium crystalloid cardioplegia was used for myocardial protection and newer techniques in anesthetic management and perioperative patient care were also employed. The method of equilibrium cardiac gated blood pool (GBP) scintigraphy was used to obtain perioperative changes in global ejection fraction (EF) and regional wall motion (RWM). Ninety percent of patients displayed a decrease in EF 2 hours postoperatively when compared to their preoperative values. This change was also associated with a fall in cardiac index (CI) and left ventricular stroke work index (LVSWI). Twenty-four hours postoperatively, EF and CI recovered to preoperative levels, but LVSWI remained depressed. Seven days postoperatively, global EF had improved to a value greater than the preoperative one (50% +/- 3% versus 57% +/- 4%, p < 0.05). Perioperative changes in RWM followed the same pattern as EF, but recovery in this index of regional contractility was faster than EF, since maximal improvement was observed 24 hours postoperatively. Thus transient left ventricular dysfunction is common immediately after CABG, but recent advances in myocardial protection and perioperative management are associated with short-term increases in regional and global left ventricular function documented by noninvasive GBP imaging.

Aged↗
PubMed1980

Early and long-term improvement in left ventricular performance following coronary bypass surgery.

Changes in left ventricular performance after coronary artery bypass grafting (CABG) have been variable. Earlier studies based on contrast left ventriculography have shown occasional improvement in left ventricular function in patients with unstable angina or abnormal preoperative ventricular performance, but for the most part repeat cardiac catheterization several months after operation has shown no significant changes in global left ventricular contraction. In the past few years, advances in radiopharmaceutical technology have made the characterization of left ventricular wall motion accurate and highly reproducible. Since prognosis in patients with coronary artery disease and survival after CABG have been related to global ejection fraction (EF), we employed prospectively on analysis of short-term and long-term changes in EF after CABG utilizing multidose hypothermic potassium crystalloid cardioplegia as the method of myocardial protection. Concomitantly, newer techniques in anesthesia and perioperative patient management were employed to minimize myocardial damage in these patients. Postoperative scintigraphic evaluation showed a transient (2-hour) depression in left ventricular function, followed by recovery to preoperative levels at 24 hours and significant improvement in EF at 7 days. From 7 days to 8 months postoperatively, there was no further change in resting EF, but there was another significant exercise-induced increase in EF at the long-term examination. Thus, present advances in the multidisciplinary management of patients with coronary artery disease are associated with improvement in resting and exercise-related EF postoperatively.

Aged↗
PubMed1979

Thoracic aortic imaging without angiography.

Imaging of the thoracic aorta without recourse to angiography has great theoretic appeal. We have used computerized tomography (CT) in the initial evaluation of 297 patients with suspected mediastinal disease. Nineteen of this group had important findings related to the thoracic aorta: aortic dissection (six), descending thoracic aortic aneurysm (nine), suspected aortic trauma (three), and suspected false aneurysm at a coarctation repair (one). In all cases, the aorta and related pathology were readily demonstrated by CT, aided by the intravenous infusion of contrast material. In 13 of 15 cases, aortic dissection and aortic aneurysm could be accurately diagnosed. In two instances of ascending aortic dissection, it was not possible to distinguish the false lumen from mural thrombus in an atherosclerotic aneurysm.

Aorta, Thoracic↗
PubMed1979

Surgical repair of esophagobronchial fistula following successful treatment of Hodgkin's disease.

A 33-year-old man with stage III-BS nodular sclerosing Hodgkin's disease received combination chemotherapy and subsequently developed a right middle lobe infiltrate in the lung unresponsive to antibiotic therapy. Thoracotomy revealed an esophagobronchial fistula with no evidence of malignancy. Surgical correction of the fistula was technically difficulty but proved lifesaving for this patient.

Adult↗
PubMed1979

A mechanical device for sutureless aorta-saphenous vein anastomosis.

The aorta-saphenous vein anastomosis is a very common anastomosis with constant anatomy. A device for sutureless aortovenous anastomosis is presented which adapts the principle of venous eversion to the end-to-side anastomosis. The use of this device in 20 dogs demonstrated that reasonable early patency (85%) and subsequent long-term patency (100%) can be achieved. The device possesses the potential for rapid multiple anastomoses to the proximal aorta, but the eversion principle requires that the anastomosis be smaller than the vein utilized. Clinical application of this technique will require both modification to enlarge the anastomosis and demonstration of long-term patency competitive with suture techniques. The device is not yet ready for clinical use.

Animals↗
PubMed1979

Computed vs. conventional tomography in evaluation of primary and secondary pulmonary neoplasms.

One hundred patients, ultimately proved to have chest malignancies, were evaluated prospectively with conventional chest tomography and computed tomography. In 58 patients with primary malignancies, conventional tomograms were more useful in evaluation of the hilus than CT scans. The mediastinum was better assessed by CT. Thus, evaluation of the presence of neoplasia is better accomplished by conventional examination, while extent of disease is best assessed by CT. Thoracotomy for curative resection was not attempted (in the latter cases of this series) based on CT findings of mediastinal involvement. In 42 patients with metastases to the chest, CT scans of the lung parenchyma were more sensitive than whole lung tomography but had little additional impact on patient treatment. Nevertheless, in 18 patients the results of CT or whole lung tomography directly affected patient therapy.

Aged↗
PubMed1977

Aortic valve replacement in the elderly. Encouraging postoperative clinical and hemodynamic results.

Seventy-three patients aged 60 and over and 277 patients under 60 years of age underwent isolated aortic valve replacement (AVR) for aortic stenosis, regurgitation, and mixed disease from 1966 through 1975. Cardiac catheterization was performed five to nine months following operation in 77% of these patients. Follow-up averaged 55 months per patient. The hospital mortality in the elderly group was 2.7%, compared to 5.8% in the younger group. The late cardiac mortality was 21% and 19%, respectively. There was significant improvement (P less than .001) in the left ventricular end-diastolic pressure, cardiac index, and functional class in each of the three disease groups in the younger as well as the elderly patients. More important, the magnitude of improvement in each of these variables in patients over and under 60 years of age was not significantly different. Increasing longevity will make cardiac operations more common in the older population. These findings indicate that AVR carries the same low risk and brings about a similar improvement in left ventricular pump function in patients older and younger than 60.

Aged↗
PubMed1977

Suspected pulmonary metastases: correlation of chest x-ray, whole lung tomograms, and operative findings.

Chest x-rays, whole lung tomograms, and operative findings were correlated in 152 patients with an extrathoracic malignancy who underwent 182 thoracotomies for the evaluation of pulmonary nodules. Among 25 patients with a normal chest x-ray but one or more pulmonary nodules demonstrated by whole lung tomography, 19 had metastatic disease documented at thoracotomy. Of 64 patients with unilateral nodules seen on conventional chest x-ray, 10 of 32 with sarcoma, 2 of 7 with melanoma, but only 2 of 25 with carcinoma had bilateral nodules demonstrated by tomography. At thoracotomy, 8 of 38 patients in whom a solitary nodule was present on both chest x-ray and on tomogram had multiple nodules. Similarly, 35 of 48 patients with more nodules seen on the tomograms than on the chest x-ray had even more extensive metastatic disease demonstrated by operation. Among patients who had resection of all metastatic pulmonary nodules, 50% of those with carcinoma and 32% of those with sarcoma who underwent resection of a solitary nodule approached that of patients with carcinoma. These findings suggest that whole lung tomograms contribute to the determination of the extent of pulmonary metastasis in patients with solid malignancies, even in the presence of a negative chest x-ray. The improved long term survival achieved by resection of these metastases may be partially attributed to this screening procedure.

Adult↗
PubMed1977

Significance of subendocardial S-T segment elevation caused by coronary stenosis in the dog. Epicardial S-T segment depression, local ischemia and subsequent necrosis.

A model of partial thickness ischemia has been developed using subendocardial S-T elevation without epicardial S-T elevation to detect partial thickness ischemia which is sufficient to cause subsequent necrosis. Subendocardial blood flow in this model (measured with radioactive microsphere techniques) may be reduced to 25 percent of normal (P less than 0.001) by coronary stenosis and tachycardia while subepicardial flow remains normal. Epicardial S-T depression seems to indicate reciprocally subendocardial S-T elevation as long as a layer of nonischemic epicardial muscle is present, but when ischemia becomes transmural, epicardial S-T elevation occurs. Regional pressure-flow relations were determined as distal coronary pressure was reduced at a constant aortic pressure, heart rate and cardiac output. These relations revealed remarkably effective autoregulation of epicardial blood flow concomitant with progressive subendocardial ischemia.

Animals↗