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Biomedical subjects

P D Myerowitz

Publications and source records attributed to P D Myerowitz.

At least 55 records · Page 3Linked to original sources
PubMed1983

Work in progress: a correction for tissue iodine accumulation in videodensitometric measurements of left ventricular ejection fraction.

Left ventricular ejection fractions were determined following eight intravenous injections in three dogs using area/length and digital videodensitometric techniques. Ejection fractions were measured by both techniques for all beats during left ventricular opacification. Even after noniodinated background corrections, tissue iodine accumulation produced large errors in measured iodine content late in the contrast material curve. By using a model for tissue iodine accumulation, an algorithm was developed that appears to reduce these errors. The measured ejection fraction for ten beats following the peak of the contrast material curve declined an average of 1.8% following correction, compared with 14% prior to correction. Following correction for tissue iodine accumulation, correlation between area/length and video-densitometric ejection fractions was 0.94. By correcting for tissue iodine accumulation, much more of the contrast material curve provides usable data for estimating ejection fractions.

Absorptiometry, Photon↗
PubMed1983

Diagnosis and management of the hypothyroid patient with chest pain.

A retrospective analysis of 38 patients undergoing cardiac catheterization with the diagnoses of hypothyroidism and chest pain revealed 23 to be euthyroid while receiving replacement therapy and 15 to be hypothyroid. Cardiac index was significantly reduced (p less than 0.01) in hypothyroid and euthyroid patients with thyroxine values between 4 and 7 micrograms/dl (2.8 +/- 0.7 and 3.0 +/- 0.9 L/min/m2, respectively), compared to euthyroid patients with thyroxine values greater than 7 micrograms/dl with or without coronary artery disease (4.0 +/- 1.2 and 4.0 +/- 0.7 L/min/m2, respectively). Ten hypothyroid patients underwent coronary artery bypass. There were no deaths, and only one patient required prolonged postoperative intubation. With a mean follow-up of 36 months, there have been no myocardial infarctions and one late death, which occurred at 7 years secondary to stroke. We conclude that preoperative thyroid replacement therapy is theoretically dangerous and may not significantly improve hemodynamics until full replacement is achieved. Coronary bypass grafting can be performed safely despite hypothyroidism with excellent early results.

Adult↗
PubMed1983

Effect of reperfusion temperature and pressure on the functional and metabolic recovery of preserved hearts.

Reperfusion conditions significantly affect recovery following global myocardial ischemia. Using an isolated dog heart model, we investigated the effect of initial (first 10 minutes) reperfusion temperature and pressure on the metabolic and functional recovery of the preserved heart. Four groups of five or six dogs each underwent 2 hours of ischemic cardioplegic arrest at 15 degrees C following single-dose crystalloid cardioplegia. Hearts were initially reperfused at 37 degrees C (high temperature) or 28 degrees C (low temperature) and at 50 mm Hg (low pressure) or 80 mm Hg (high pressure), giving four groups: (1) high-temperature, high-pressure; (2) high-temperature, low-pressure; (3) low-temperature, high-pressure; and (4) low-temperature, low-pressure. Septal temperatures were continuously recorded. Ventricular function curves 1 and 2 hours following reperfusion were significantly depressed in the high-temperature, high-pressure group (70%, p less than 0.01, and 83%, p less than 0.02) and the low-temperature, high-pressure group (78%, p less than 0.03, and 85%, p less than 0.03) but were normal in the low-temperature, low-pressure and the high-temperature, low-pressure groups. All groups showed edema 1/2 hour after reperfusion as measured by water and sodium content in myocardial biopsy specimens but only the high-temperature, high-pressure and the low-temperature, high-pressure groups showed persistent edema at 3 hours (3.95 +/- 0.2 ml H2O/gm dry weight, p less than 0.03 and 3.99 +/- 0.16 ml/gm, p less than 0.02, respectively). Only low-temperature, high-pressure reperfusion resulted in statistically significant reductions in adenosine triphosphate (ATP) 1/2 hour and 2 hours following reperfusion (a 15% reduction from baseline). Maximum rewarming rates were measured for each group. High-temperature, high-pressure = 2 degrees C per second; low-temperature, high-pressure = 1 degree C per second; high-temperature, low-pressure = 0.75 degrees C per second; and low-temperature, low-pressure = 0.4 degrees C per second. High-pressure reperfusion following global myocardial ischemia results in rapid rewarming and is associated with prolonged myocardial edema, depressed ATP levels, and delayed functional recovery. Therefore, we employ 10 minutes of low-pressure reperfusion in our patients undergoing potassium cardioplegic arrest.

Animals↗
PubMed1982

Digital subtraction angiography: present and future uses in cardiovascular diagnosis.

Digital subtraction angiography (DSA) has been proved to be an effective means of visualizing the cardiovascular system following intravenous injection of contrast material. Excellent quality images have been obtained of the left ventricle, the thoracic aorta and its major branches, the carotid arteries, the abdominal aorta and its major branches, lower extremity vessels, and intracerebral vessels. Avoiding the risks and discomforts of direct arterial puncture and the need for hospitalization, DSA is safer and more economical than standard arteriography. It is, therefore, useful both as a screening tool and, in many patients, as a diagnostic tool for the evaluation of vascular disease. Left ventricular studies provide excellent qualitative and quantitative evaluation of left ventricular function. Arterial injections of contrast have provided excellent quality images of the vascular tree with low volume dilute contrast material. Lower extremity vessels not visualized by standard arteriography have been seen following intra-arterial contrast injections using DSA. Aortic root injections have been used to demonstrate coronary arteries and coronary artery bypass grafts. Although intravenous injections of contrast have shown coronary artery bypass graft patency with reasonable success, they have not proved useful at this point in defining the exact anatomy. Other video techniques following arterial injections of contrast have been used to calculate vessel flows. Although coronary artery images in animal studies following intravenous contrast injection are improving, they are still not of diagnostic quality. Digital subtraction angiography, therefore, has proved itself a useful adjunct to standard arteriographic techniques. Its future potential has not yet been defined.

Angiography↗
PubMed1982

A technique of scatter and glare correction for videodensitometric studies in digital subtraction videoangiography.

The logarithmic amplification of video signals and the availability of data in digital form make digital subtraction videoangiography a suitable tool for videodensitometric estimation of physiological quantities. A system for this purpose was implemented with a digital video image processor. However, it was found that the radiation scattering and veiling glare present in the image-intensified video must be removed to make meaningful quantitations. An algorithm to make such a correction was developed and is presented. With this correction, the videodensitometry system was calibrated with phantoms and used to measure the left ventricular ejection fraction of a canine heart.

Absorptiometry, Photon↗
PubMed1982

Digital subtraction angiography as a method of screening for coronary artery disease during peripheral vascular angiography.

Since myocardial infarction is the major cause of perioperative and postoperative death following peripheral vascular surgery, an accurate method of screening for coronary artery disease in this group of patients is needed. Digital subtraction angiography (DSA) with the use of intra-arterial aortic root injection of contrast material was evaluated as a method of screening for coronary artery disease in patients undergoing angiography for peripheral vascular disease. The feasibility of this method was demonstrated in animal experiments. Fifteen milliliters of Renografin-76 was power injected into the aortic root of seven anesthetized 20 kg mongrel dogs. Normal coronary artery anatomy was clearly demonstrated with DSA, and a series of iatrogenically created stenoses and occlusions were accurately identified. Excellent definition of patent grafts to the left anterior descending and circumflex coronary arteries was obtained in two dogs that had undergone previous coronary artery bypass grafting. A balloon occluder on one graft was used to demonstrate partial and near-total obstruction of the bypass graft. We are currently studying the use of aortic root injections using DSA to determine coronary artery disease in patients having standard angiography for peripheral vascular disease. Adequate visualization of coronary arteries and bypass grafts with only 20 ml of contrast has been obtained. The potential ability of this technique to identify and allow treatment of life-threatening coronary artery lesions in patients prior to or simultaneously with peripheral vascular surgery may result in reduced mortality.

Angiography↗
PubMed1982

Computerized fluoroscopy: new technique for the noninvasive evaluation of the aorta, coronary artery bypass grafts, and left ventricular function.

A computerized fluoroscopy system has been developed on the basis of real-time digital processing of x-ray transmission data from traditional image-intensified fluoroscopy equipment. High-quality visualization of any part of the arterial system is obtained following intravenous injection of 0.5 to 0.75 ml/kg of iodinated contrast materials. This report describes the use of this technique to evaluate the aortic arch, left ventricular function, and coronary artery bypass graft patency. Fifty intravenous studies were performed in 25 patients. Among 20 patients with coronary artery bypass grafts, computerized fluoroscopy correctly identified 11 of 15 patent grafts and 11 of 11 occluded grafts as confirmed by standard coronary arteriography in 11 of these patients. Unlike computerized tomography, our technique gives a longitudinal view of the bypass graft much like direct coronary angiography. Aortic arch studies included demonstration of a right aortic arch with a small left subclavian artery, a coarctation, and a normal aortic arch in a trauma patient with a wide mediastinum. Segmental wall motion abnormalities were clearly identified by a modification of the technique which produces a negative outline on the ventriculogram in dyskinetic segments. Ejection fractions may be calculated by determining the amount of iodine in the ventricle in systole and diastole. This technique may also be used to evaluate carotid disease and peripheral vascular disease in patients undergoing coronary artery bypass procedures. Computerized fluoroscopy, therefore, allows evaluation of the entire cardiovascular system by the relatively noninvasive technique of intravenous angiography.

Angiography↗
PubMed1982

Digital subtraction angiography and B-mode ultrasonography for abdominal and peripheral aneurysms.

Thirty-two patients suspected of having intraabdominal and/or peripheral aneurysms were evaluated by digital subtraction angiography (DSA) and B-mode ultrasonography to determine whether diagnostic accuracy and operative management could be improved by this combination of preoperative studies. Abdominal B-mode ultrasonography accurately diagnosed most primary aortic aneurysms and correctly determined their size (93%) but missed iliac artery aneurysms in 75% of cases. Failures resulted from severe ileus and the inability to scan the intrapelvic iliac vessels. Abdominal ultrasound studies were false positive for aortic pseudoaneurysms in two of four cases. DSA correctly identified all but one intra-abdominal aneurysm but did not always correctly determine their size because of intraluminal clot. DSA identified a number of associated peripheral vascular lesions, which ultrasonography could not. All primary peripheral aneurysms were correctly diagnosed by ultrasound, but nearly half of the ultrasound studies were false positive for femoral pseudoaneurysms. DSA correctly identified all peripheral aneurysms and at the same time provided anatomic information about vessels proximal and distal to these lesions needed for surgical planning. Digital subtraction angiography combined with ultrasonography is diagnostically accurate and provides adequate anatomic information for planning surgical management of these aneurysms.

Abdomen↗
PubMed1981

Recent advances in the management of thoracic surgical infections.

Current management of infections in thoracic surgery is reviewed. The selection of patients for the use of antibiotics prophylactically, the diagnosis and treatment of pulmonary infection in immunosuppressed patients, indications for operation in patients with fungal infections, bronchiectasis, lung abscess, and empyema, and the management of mediastinitis after sternotomy and of postpneumonectomy space infections is described.

Amphotericin B↗
PubMed1980

Computerized fluoroscopy: digital subtraction for intravenous angiocardiography and arteriography.

Computerized fluoroscopy is a system comprising on-line digital time and energy subtraction algorithms designed to isolate and enhance the iodine signal from image intensified fluoroscopy. The apparatus is described and its use for time subtraction intravenous arteriography of the carotid, abdominal, extremely arteries, as well as the heart, is illustrated. Vascular diseases such as stenoses, obstruction, emboli, ulcerative plaques, and aneurysms are readily demonstrated. The technique has a potential for evaluating cardiac motion and the patency of coronary artery bypass grafts. The method appears to be a safe and less expensive alternative to catheter arteriography and angiocardiography in certain instances.

Adult↗
PubMed1979

Surgical treatment of recurrent primary malignant tumor of the left atrium.

A young woman presented with a tumor in the left atrium resembling a left atrial myxoma. After simple excision of the tumor the diagnosis of primary malignant fibrous histiocytoma of the heart was made. A course of radiation therapy was given. Four subsequent recurrences were treated by cardiotomy and resection of the left atrial wall. At the third, fourth, and fifth operations fulguration of the left atrial wall was performed. Subsequent chemotherapy failed to control the tumor. The patient was admitted 6 weeks after the last resection and died. Postmortem examination revealed a large recurrent tumor obstructing the left atrium with no metastases. The clinical course, cardiac catherization data, and postmortem examination are presented. Palliation was achieved by repeated resection of a radiation-resistent primary sarcoma of the heart.

Adult↗
PubMed1979

Earlier operation for left-sided Pseudomonas endocarditis in drug addicts.

Three consecutive patients with Pseudomonas endocarditis were treated by early operation with no deaths. The indications for operation were severe failure, systemic embolization, and infection refractory to antibiotics. The organism is aggressive, characterized by early invasion of the myocardium. Wide débridement of the anulus is necessary to remove any vegetations or intramyocardial abscessed wall. Because multiple valve infection is common, it is important to evaluate all four cardiac valves at the time of operation. Removing a second rim of the mitral anulus for separate culture at the time of mitral valve replacement may demonstrate the degree to which the valve resection has removed all infection. Early operation is necessary for reinfection of the prosthetic valve; however, metastatic abscess should also be considered in the face of continued signs of infection postoperatively. Patients should receive a 6 week postoperative course of antibiotics which have been shown by in vitro testing to be serum bactericidal in at least a 1:8 dilution. The operative findings of invasion of the myocardium by the organism and the surgical success in this small series have resulted in our recommending earlier operation in patients with these indications.

Adult↗
PubMed1977

Open-heart surgery.

A randomized prospective study of the relative effectiveness of broad-spectrum versus specific antistaphylococcal antibiotic prophylaxis in open-heart surgery was done between May 1972 and June 1973. All patients undergoing open-heart surgery were assigned randomly (by hospital number) to receive either methicillin (M) or cephalothin (C) beginning the night before operation. There were 132 patients in the C group and 129 in the M group. There were no statistically significant differences in age or duration of hospitalization, cardiopulmonary bypass, urinary tract drainage, or postoperative fever. There was a significant difference in the ratio of male to total patients (0.67 C, 0.52 M, P less than .02) and duration of operation in hours (4.27 C, 3.87 M, P less than .02). A statistically significant higher rate of urinary tract infection (3 C, 22 M, P less than .05), pneumonia (0 C, 9 M, P less than .01), and episodes of sepsis and prosthetic endo carditis (0 C, 11 M, P less than .001) was found in the methicillin group. The incidence of wound infections and positive cultures from blood obtained immediately after termination of cardiopulmonary bypass was not significantly different. Cephalothin replaced methicillin as the routine antibiotic prophylaxis for open-heart surgery at our institution.

Adult↗
PubMed1977

Antibiotic prophylaxis for open-heart surgery.

A randomized, prospective study of the relative effectiveness of broad-spectrum versus specific antistaphylococal antibiotic prophylaxis in patients having open-heart surgery was performed between May, 1972, and June, 1973. All patients undergoing open-heart surgery was assigned randomly (by hospital number) to receive either methicillin or cephalothin beginning the night before operation. There were 132 patients in the cephalothin group and 129 in the methicillin group. There was no statistically significant differences in age or duration of hospitalization, cardiopulmonary bypass, urinary tract drainage, or postoperative fever. There was a significant difference in the ratio of male to total patients (cephalothin group, 0.67; methicillin group, 0.52; p less than 0.02) and duration of operation (cephalothin group, 4.27 hours; methicillin group, 3.87 hours; p less than 0.05). The methicillin group had a statistically significant higher rate of urinary tract infection (cephalothin group, 3 cases; emthicillin group, 22 cases, p less than 0.05), pneumonia (cephalothin group, no cases; methicillin group, 9 cases; p less than 0.01), and episodes of sepsis and prosthetic valve endocarditis (cephalothin group, no cases; methicillin group, 11 cases, p less than 0.001). The incidence of wound infections and positive blood cultures from blood obtained immediately after termination of cardiopulmonary bypass was not significantly different between the two groups. Cephalothin has replaced methicillin as the routine prophylaxis for open-heart surgery at our institution.

Bacterial Infections↗