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Biomedical subjects

F M Clements

Publications and source records attributed to F M Clements.

26 records · Page 2Linked to original sources
PubMed1989

Silent myocardial ischemia in patients undergoing peripheral vascular surgery: incidence and association with perioperative cardiac morbidity and mortality.

Atherosclerosis is a systemic disorder and coronary artery disease is highly prevalent in patients treated for lower-extremity obstructive vascular disease. Myocardial ischemia and infarction represent the most frequent and most clinically important complications of surgical procedures for lower-extremity revascularization. Despite attempts in several areas, no practical, sensitive, and specific method for identifying patients at highest risk for myocardial events postoperatively has been found before now. This study reports observations on a consecutive series of 50 patients who underwent continuous perioperative electrocardiographic monitoring with a microprocessor-based electrocardiographic ischemia monitor. Thirty-eight percent of the patients were found to have episodes of ischemia; most of these episodes were painless and would not otherwise have been recognized. Ischemia was most prominent in the postoperative rather than the preoperative or intraoperative phases. Tachycardia was often associated with ischemia. Significantly more cardiac-related morbidity and deaths occurred in patients who were documented to have silent myocardial ischemia. In fact, no cardiac events occurred in the 31 patients without ischemia (p less than 0.02). This type of ischemia monitoring represents a potential method for segregating patients at high risk for cardiac-related morbidity and death during lower-extremity revascularization.

Coronary Disease↗
PubMed1989

Assessment of left ventricular functional preservation during isolated cardiac valve operations.

To evaluate intraoperative changes in myocardial performance during valvular operations, ventricular functional measurements were obtained in 16 patients before and after elective cardiac valvular replacement. Six patients had mitral regurgitation, four had mitral stenosis, and six had calcific aortic stenosis; all patients underwent isolated mitral or aortic valve replacement. Cold potassium crystalloid cardioplegia, topical hypothermia, and low-flow systemic hypothermia were employed uniformly. Just before and 10 minutes after cardiopulmonary bypass was discontinued, left ventricular pressure and volume data were recorded at four to five different steady-state levels of filling produced by blood infusion or withdrawal from the aortic cannula (mean end-diastolic pressure range, 10-22 mm Hg; mean end-diastolic volume range, 120-168 ml). Portable first-pass radionuclide ventriculography and simultaneous micromanometry were used for construction of left ventricular pressure-volume loops from which stroke work and end-diastolic volume were calculated. Two-dimensional transesophageal echocardiograms also were recorded, and epicardial pacing maintained heart rate as constant as possible. As compared with prebypass measurements, echocardiographic left ventricular wall volume changed insignificantly after the valvular procedures (178-181 ml/m2, p greater than 0.5). The stroke work-end-diastolic volume relationship before and after operation was highly linear in all studies (mean = 0.97). The slope and x intercept of this relationship did not change significantly after operation, indicating a stable level of left ventricular function (from 12.7 x 10(4) to 10.0 x 10(4) ergs/ml and from 67 to 57 ml, respectively; p greater than 0.3).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiopulmonary Bypass↗
PubMed1988

Noninvasive cardiac monitoring.

During the past few years a number of technological developments have made new methods of noninvasive cardiac monitoring available for use in the intensive care unit. Some of these can be used almost continuously some repeatedly, but intermittently, to manage critically ill patients. In addition to avoiding the risks of pain, bleeding, and infection associated more with invasive studies, a major advantage of many noninvasive studies is that one is able to conduct them at the bedside. Echocardiography has been most useful in this regard, but now even nuclear imaging can be carried out with commercially available portable scanners. Doppler techniques, formerly understood only by those with considerable background in cardiology have now evolved to provide the clinician with a simple method of measuring cardiac output. ECG monitoring too has undergone recent refinements to automate the detection of ST segment changes that escape routine observation of the bedside monitor.

Cardiac Output↗
PubMed1987

Intraoperative transesophageal color flow mapping: initial experience.

Transesophageal Doppler color flow mapping (TEDCFM) is a new ultrasound modality now being developed. It provides a convenient, noninvasive way to image cardiac anatomy and intracardiac blood flow that is applicable to intraoperative use. We describe its use in one normal subject and seven cardiac surgical patients. Blood flow characteristics as visualized by TEDCFM are described for these patients. Transesophageal Doppler color flow mapping provided specific information about the presence, site, and severity of mitral regurgitation, aortic regurgitation, and interatrial shunting. Paravalvular leak was detected in one patient after mitral valve replacement. The intimal tear of a type I aortic dissection was located with positive identification of the true and false lumina. A high incidence of mild asymptomatic mitral regurgitation was found in patients undergoing coronary artery bypass grafting (CABG).

Cardiac Surgical Procedures↗