Biomedical subjects

R C Agnew

Publications and source records attributed to R C Agnew.

3 recordsLinked to original sources

PubMed1996

Valve replacement in aortic stenosis with preoperative mean gradient < 50 mmHg: hemodynamic outcome.

BACKGROUND AND AIMS OF THE STUDY: No prior studies have defined pre- versus postoperative hemodynamics of large numbers of patients with low mean transvalvular gradients. This was our objective. METHODS: Retrospective analysis was undertaken of preoperative and postoperative echo/Doppler data in 294 patients who underwent aortic valve replacement (AVR) for aortic stenosis (AS). Some 136 patients had a preoperative mean gradient of < 50 mmHg. The relationship of preoperative to pre- minus postoperative (delta) mean gradient (GRAD), peak valvular velocity (V2), left ventricular outflow tract velocity (V1), V1/V2 ratio, V2-V1, and aortic valve area (AVA) were plotted and analyzed such that a 'zero-benefit threshold' from surgery could be estimated. RESULTS: Strong relationships (r > 0.80) were noted for GRAD to delta GRAD, V2 to delta V2, and (V2-V1) to delta (V2-V1) with zero-benefit thresholds of 16 mmHg for GRAD, 2.6 m/s for V2 and 1.7 m/s for V2-V1. These thresholds were lower in patients who received homografts (11 mmHg, 2.2 m/s, and 1.1 m/s respectively), p < 0.02. The relationship of pre operative V1/V2 to delta V1/V2 and AVA-delta AVA were weaker (r = 0.52 and 0.33 respectively) with zero-benefit thresholds of 0.41 and 2.0 cm2. Among patients with depressed preoperative fractional shortening, improvement was confined to those without coexistent coronary artery disease. CONCLUSION: This analysis of thresholds of mean gradient benefit suggests that most patients with low gradient AS improve hemodynamically from AVR. The hemodynamic 'break-even' point averages a mean gradient of 16 mmHg.

Aged↗

PubMed1988

Retrograde coronary sinus perfusion.

"Redo" operations for coronary artery disease have become commonplace. One of the major complications that occurs is perioperative infarction due to embolization of atheromatous material from diseased veins into the distal coronary arteries. Because of this, we began using retrograde coronary sinus perfusion (RCSP) for delivery of cardioplegia to prevent the embolization of grumous material. It is our belief that retrograde flow through the coronary arteries is an effective preventive measure. In addition, RCSP is a simple method of delivery in redo operations such as aortic valve replacement where the majority of coronary flow is through patent vein grafts. Sixty-five of approximately 3,100 patients in our practice in the past three years underwent a cardiac operation in which RCSP was used for cardioplegia delivery. Ventricular function in all patients was well preserved, and all survived. There were no complications associated with the use of this method.

Cardiac Surgical Procedures↗

PubMed1985

Perioperative ischemic injury after coronary bypass graft surgery.

Two hundred twelve patients who underwent isolated coronary bypass graft surgery were prospectively evaluated for perioperative ischemic injury. All patients underwent preoperative and postoperative testing with technetium 99m pyrophosphate first-pass ventriculography combined with myocardial uptake scans, 12-lead electrocardiography, and serial creatinine phosphokinase MB determination. Fifteen percent of the patients had ischemic injury with at least two test results positive, but only 4 percent had positive results of all three tests. No single test proved adequate. Enzyme levels were highly sensitive and had value as a screening test. The electrocardiogram was specific but only moderately sensitive. The single best test was the radionuclide scan with good sensitivity and no false-positive results. All three tests are required to rigorously diagnose ischemic injury.

Coronary Artery Bypass↗