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Mackenzie Quantz

Publications and source records attributed to Mackenzie Quantz.

5 recordsLinked to original sources
PubMed2007

Monitoring brain oxygen saturation during coronary bypass surgery: a randomized, prospective study.

BACKGROUND: Cerebral deoxygenation is associated with various adverse systemic outcomes. We hypothesized, by using the brain as an index organ, that interventions to improve cerebral oxygenation would have systemic benefits in cardiac surgical patients. METHODS: Two-hundred coronary artery bypass patients were randomized to either intraoperative cerebral regional oxygen saturation (rSO2) monitoring with active display and treatment intervention protocol (intervention, n = 100), or underwent blinded rSO2 monitoring (control, n = 100). Predefined clinical outcomes were assessed by a blinded observer. RESULTS: Significantly more patients in the control group demonstrated prolonged cerebral desaturation (P = 0.014) and longer duration in the intensive care unit (P = 0.029) versus intervention patients. There was no difference in overall incidence of adverse complications, but significantly more control patients had major organ morbidity or mortality (death, ventilation >48 h, stroke, myocardial infarction, return for re-exploration) versus intervention group patients (P = 0.048). Patients experiencing major organ morbidity or mortality had lower baseline and mean rSO2, more cerebral desaturations and longer lengths of stay in the intensive care unit and postoperative hospitalization, than patients without such complications. There was a significant (r(2) = 0.29) inverse correlation between intraoperative rSO2 and duration of postoperative hospitalization in patients requiring > or =10 days postoperative length of stay. CONCLUSION: Monitoring cerebral rSO2 in coronary artery bypass patients avoids profound cerebral desaturation and is associated with significantly fewer incidences of major organ dysfunction.

Adult↗
PubMed2005

Laser lead extraction: is there a learning curve?

Laser extraction of device leads offers an attractive alternative to countertraction and electrosurgical dissection sheath, potentially increasing efficacy and reducing complications. Wider adoption of this technology depends on relative ease of use. We report the experience of a new center to define the "learning curve." We performed 76 laser lead extractions in 75 patients (age 63 +/- 17 years, 59 male) from July 2001 to January 2004. Two experienced device implanters who were novice extractors underwent a 2-day site visit to a high volume extraction center for training. Lead extractions were performed in the operating room with immediate surgical backup. The indication for extraction was infection in 39 (systemic in 15), erosion or pain in 11, and lead related or debulking in 25. Complete removal was achieved in 139 of 145 leads (14 ICD, 131 pacemaker). Partial removal (<4 cm retained) was achieved in five leads (4%), and one lead could not be extracted. Complete success was 95% in the first third of patients, 94% in the second third, and 100% in the latter third. Fluoroscopy time fell from 19 +/- 22 minute in the first third of patients to 11 +/- 8 minute in the second third to 8 +/- 4 minute in the latter third (ANOVA P = 0.02). No major complications occurred. Local bleeding required minor left subclavian vein repair in two individuals. Symptomatic venous thrombosis occurred in 3 of the first 11 cases 1-21 days after extraction, but did not occur in the next 64 consecutive patients who received a 1-month anticoagulation regimen (27% vs 0%, P < 0.001). One patient developed venous thrombosis 3 weeks following cessation of warfarin therapy. Practice guidelines reasonably recommend appropriate training prior to independent performance of lead extraction. The current study suggests that experienced device implanters with appropriate operative backup taking a limited, but intensive training program can be safe and effective at lead extraction in a short time, in part a reflection of the improved technology.

Aged↗
PubMed2004

Design and manufacture of a polyvinyl alcohol (PVA) cryogel tri-leaflet heart valve prosthesis.

Although current artificial heart valves are life sustaining medical devices, improvements are still necessary to address deficiencies. Bioprosthetic valves have a compromised fatigue life, while mechanical valves have better durability but are prone to thromboembolic complications. A novel, one-piece, tricuspid valve, consisting of leaflets, stent and sewing ring, made entirely from the hydrogel, polyvinyl alcohol cryogel (PVA-C), has been developed and demonstrated. This valve has three thin leaflets attached to a cylindrical stent. In order to approximate the complex shape of the surface of the natural heart valve leaflets, two different geometries have been proposed: revolution about an axis of a hyperboloid shape and revolution about an axis of an arc subtending (joining) two straight lines. The parameters of both geometries were examined based on a compromise between avoiding sharp curvature of leaflets and minimization of the central opening of the valve when closed. The revolution of an arc subtending two straight lines was selected as the preferred geometry since it has the benefit of a smaller central opening when the value of the maximum curvature for the leaflets is the same for each valve geometry. A cavity mold has been designed and constructed to form the PVA-C heart valve. The three leaflets were formed and integrated into the stent and sewing ring in a single process. Prototype heart valves were manufactured in the mold from a solution of PVA and water, by controlled freezing and thawing cycles.

Animals↗
PubMed2003

Advantages of the intrabreath technique as a measure of lung function before and after heart transplantation.

BACKGROUND: Pulmonary function testing is an integral part of evaluating patients who are being considered for cardiac transplantation. The accurate measurement of diffusing capacity (DLCO) and alveolar volume (VA) is dependent on a 10-s breath-holding maneuver that may be difficult for patients with congestive heart failure to perform. The intrabreath (IB) technique is not dependent on a breath-holding maneuver and may provide more accurate pulmonary function testing results in chronically debilitated patients. METHODS: Seventy-five patients performed maneuvers with IB and single-breath (SB) techniques during evaluation for heart transplantation and at 3 and 12 months following transplantation. The DLCO, VA, and total lung capacity (TLC) were compared using Pearson correlation coefficients, a Student t test, and intercorrelation coefficients. RESULTS: The DLCO and VA, when determined with the IB technique, had excellent correlations to the SB technique over all ranges of DLCO values. VA values that were determined by the IB technique were greater than those determined by the SB technique and more closely approximated the TLC values. The satisfactory correlation between the two techniques was maintained when DLCO was corrected for VA. However, due to the lower values for VA as determined by the SB method, the corrected measurements were consistently higher for the SB technique. CONCLUSION: Pulmonary function can be measured accurately in a population of patients with long-standing congestive heart failure, both before and after cardiac transplantation, using the IB technique. Furthermore, the IB technique may provide a more accurate measurement of VA.

Female↗