PubMed Health⌕ Search

Biomedical subjects

J R Pepper

Publications and source records attributed to J R Pepper.

At least 19 recordsLinked to original sources
PubMed2006

Clinical performance with the Levitronix Centrimag short-term ventricular assist device.

BACKGROUND: The Levitronix ventricular assist device (VAD) is a centrifugal pump designed for extracorporeal support and that operates without mechanical bearings or seals. The rotor is magnetically levitated so that rotation is achieved without friction or wear, which seems to minimize blood trauma and mechanical failure. The aim of this study is to report our early results with the Levitronix Centrimag device. METHODS: Between June 2003 and April 2005, 18 patients (pts) were supported using the Levitronix at our institution. Fourteen were male. Mean age was 40.3 +/- 18.3 (range 8 to 64) years. Indications for support at implantation were: post-cardiotomy cardiogenic shock in 12 cases (Group A), and bridge to decision regarding long-term ventricular support in 6 cases (Group B). RESULTS: Mean support time was 14.2 +/- 15.2 days for all patients (range 1 to 64 days). Operative (30-day) mortality was 50% (9 pts). Six pts were in Group A and 3 pts were in Group B. Overall, 6 pts (33%) were discharged home and are presently alive and well (mean follow-up 13 months, range 5 to 17 months). Bleeding requiring re-operation occurred in 8 cases (44%), cerebral thromboembolism in 1 and pulmonary embolism in 1. There were no device failures. CONCLUSIONS: The Levitronix functioned well and proved to be useful in patients with extremely poor prognosis previously considered non-suitable for a long-term assist device. The device was technically easy to implant and manage. There was no device dysfunction and complications were acceptable or consistent with other devices. Survival to explant or a definitive procedure (VAD or transplantation) was encouraging.

Adolescent↗
PubMed2003

Toward totally endoscopic coronary artery surgery.

BACKGROUND: Here we explore a method of using robotics to reduce morbidity and mortality in conventional coronary surgery. METHODS: Using a robotic surgical system two surgeons completed five steps: (1) 80 synthetic suture exercises; (2) 76 left internal thoracic artery to left anterior descending (LIMA-to-LAD) on porcine hearts; (3) cadaveric port placement for assessing optimal access; (4) endoscopic stabilization in the live porcine model; and, finally (5) eight clinical LIMA-to-LADs performed robotically. RESULTS: After 70 hours training, mean dry lab times fell from 7.0 and 5.8 min to 5.7 and 5.1 min in the two surgeonstab series. Wet lab times fell from 40.1 and 28.5 min to 28.8 and 19.2 min. In the clinical series of eight patients there were no mortalities; all had uncomplicated postoperative recovery and all were angina free at 6-week follow-up. CONCLUSION: The learning curve for robotic training is short, and reproducible results can be achieved clinically, after appropriate training, resulting in real patient benefit.

Animals↗
PubMed2003

Innocent victim of a localised outbreak: legionella endocarditis.

Legionella pneumophila endocarditis is extremely rare. The case of a fit 26 year old man who had previously undergone homograft aortic root replacement is reported. He was admitted with legionella pneumonia during the recent localised outbreak but went on to develop endocarditis. His aortic valve was replaced with a mechanical valve and he made an uneventful recovery. Public health issues and diagnosis in susceptible patients during localised outbreaks are discussed.

Adult↗
PubMed2002

Study of five cell salvage machines in coronary artery surgery.

We evaluated the effectiveness, ease of use and safety of five machines for blood salvage during coronary artery surgery. All were equally effective in concentrating red cells. We measured haemoglobin, packed cell volume, free haemoglobin, white cells, neutrophil elastase, platelets, thrombin-antithrombin complex (TAT), prothrombin activation peptide F1.2, fibrin degradation product (d-dimers), tissue plasminogen activator (tPA) and heparin in wound blood, in washed cell suspensions and in a unit of bank blood prepared for each patient. All machines were equally safe and easy to use and were equally effective in removing heparin and the physiological components measured. There were no adverse effects on patients. Clotting factors are severely depleted both in salvaged blood, even before washing, and in bank blood. Cell savers are a valuable adjunct to coronary artery surgery, but careful monitoring of coagulation is required when the volumes of either bank blood or salvaged blood are large.

Adult↗
PubMed2002

Giant cell arteritis confined to intramural coronary arteries. Unforeseen hazards myocardial protection.

A 74-year-old woman underwent elective double valve replacement (aortic and mitral) for rheumatic valvular disease. She failed to wean from cardiopulmonary bypass due to marked left ventricular dysfunction. At autopsy, severe giant cell arteritis confined to the intramural coronary arteries was seen. Furthermore, there were multiple areas of recent microscopic myocardial infarction around the intramural coronary arteries. This report describes a rare case of giant cell arteritis confined to intramural coronary arteries which lead to inadequate myocardial protection at the time of surgery.

Aged↗
PubMed2001

Risk of iron overload is decreased in beating heart coronary artery surgery compared to conventional bypass.

Conventional cardiopulmonary bypass surgery (CCPB) increases the iron loading of plasma transferrin often to a state of plasma iron overload, with the presence of low molecular mass iron. Such iron is a potential risk factor for oxidative stress and microbial virulence. Here we assess 'off-pump' coronary artery surgery on the beating heart for changes in plasma iron chemistry. Seventeen patients undergoing cardiac surgery using the 'Octopus' myocardial wall stabilisation device were monitored at five time points for changes in plasma iron chemistry. This group was further divided into those (n=9) who had one- or two- (n=8) vessel grafts, and compared with eight patients undergoing conventional coronary artery surgery. Patients undergoing beating heart surgery had significantly lower levels of total plasma non-haem iron, and a decreased percentage saturation of their transferrin at all time points compared to conventional bypass patients. Plasma iron overload occurred in only one patient undergoing CCPB. Beating heart surgery appears to decrease red blood cell haemolysis, and tissue damage during the operative procedures and thereby significantly decreases the risk of plasma iron overload associated with conventional bypass.

Adult↗
PubMed2001

Quantitative myocardial cytokine expression and activation of the apoptotic pathway in patients who require left ventricular assist devices.

BACKGROUND: Molecular mechanisms underlying the deterioration of patients undergoing LV assist device (LVAD) implantation remain poorly understood. We studied the cytokines tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta and IL-6 and the terminal stage of the apoptotic pathway in patients with decompensating heart failure who required LVAD support and compared them with patients with less severe heart failure undergoing elective heart transplantation. METHODS AND RESULTS: Myocardial and serum samples from 23 patients undergoing LVAD implantation were compared with those from 36 patients undergoing elective heart transplantation. Myocardial TNF-alpha mRNA (1.71-fold; P<0.05) and protein (3.43+/-0.19 versus 2.95+/-0.10 pg/mg protein; P<0.05) were elevated in the LVAD patients. Immunocytochemistry demonstrated TNF expression in the myocytes. Serum TNF-alpha was also elevated (12.5+/-1.9 versus 4.0+/-0.4 pg/mL; P<0.0001) in the LVAD patients. IL-6 mRNA (2.57-fold higher; P<0.005) and protein (27.83+/-9.35 versus 4.26+/-1.24 pg/mg protein; P<0.001) were higher in the LVAD candidates, as was serum IL-6 (79.3+/-23.6 versus 7.1+/-1.6 pg/mL; P<0.0001). Interleukin-1beta mRNA expression was 9.78-fold higher in the LVAD patients (P<0.001). iNOS mRNA expression was similar to that in advanced heart failure patients and was not further elevated in the LVAD patients. Levels of procaspase-9 (8.02+/-0.91 versus 6.16+/-0.43 oligodeoxynucleotide [OD] units; P<0.01), cleaved caspase-9 (10.02+/-1.0 versus 7.34+/-0.40 OD units; P<0.05), intact and spliced DFF-45 (4.58+/-0.75 versus 2.84+/-0.23 OD units; P<0.05) were raised in LVAD patients, but caspase-3 and human nuclease CPAN were not. CONCLUSIONS: Elevated TNF-alpha, IL-1beta, and IL-6 and alterations in the apoptotic pathway were found in the myocardium and elevated TNF-alpha and IL-6 in serum of deteriorating patients who required LVAD support. These occurrences may have therapeutic implications and influence the timing of LVAD insertion.

Adolescent↗
PubMed2001

Changes in aortic rotational flow during cardiopulmonary bypass studied by transesophageal echocardiography and magnetic resonance velocity imaging: a potential mechanism for atheroembolism during cardiopulmonary bypass.

The human aorta is a curved conduit with a complex three-dimensional geometry. The curvature influences axial velocity distribution and introduces transverse velocity components. Rotational flow in the aorta can be demonstrated during normal pulsatile flow using transesophageal echocardiography. Cardiopulmonary bypass may affect the pattern of rotational flow in the aorta and thus influence the generation of atheroemboli. We investigated rotational flow in the descending aorta using color flow mapping and pulse-wave Doppler on transesophageal echocardiography before and during cardiopulmonary bypass. We correlated our findings with magnetic resonance velocity imaging in a model of a human aortic arch connected to a cardiopulmonary bypass circuit. Before cardiopulmonary bypass, rotational flow in the descending aorta was seen in 37 of 40 patients (93%). In the majority of these patients, rotational flow was in the clockwise direction during systole, looking in the direction of flow (30 of 37 patients, 81%, P < 0.01 vs counterclockwise rotation). During cardiopulmonary bypass, there were almost equal numbers of patients with clockwise (18 patients) and counterclockwise rotation (19 patients). Forty-seven percent of patients with clockwise rotation before cardiopulmonary bypass developed reversal in the direction of rotation to counterclockwise during cardiopulmonary bypass. Twenty-nine percent of patients with counterclockwise rotation developed reversal of the direction of rotation during cardiopulmonary bypass. The transverse velocity component increased during cardiopulmonary bypass regardless of the direction of rotation. We also demonstrated clockwise rotation in the descending aorta of a human aortic arch model connected to a cardiopulmonary bypass circuit using magnetic resonance velocity mapping. Before cardiopulmonary bypass, rotation was predominantly clockwise, while during cardiopulmonary bypass, there was no preferred direction of rotation. The geometry of the aorta, which is fairly constant in all patients, imposes handedness to aortic flow before cardiopulmonary bypass. However, during cardiopulmonary bypass, other extrinsic factors such as aortic cannula orientation may influence the direction of rotation. The change in direction of rotational flow and increase in its transverse velocity component during cardiopulmonary bypass may have implications for atheroembolism and arterial branch perfusion during extended periods of non-pulsatile flow.

Aorta↗
PubMed2001

Lung volume reduction surgery in a ventilated patient with severe pulmonary emphysema.

There are a limited number of reports in the literature cocerning lung volume reduction surgery in patients receiving mechanical ventilation. We present a case in which a ventilator-dependent patient with apparent endstage pulmonary emphysema underwent lung volume reduction with a successful outcome. Although the role of this procedure for selected nonventilated patients has been widely discussed its use in ventilated patients is still not clearly defined. We show that lung volume reduction surgery may facilitate ventilatory weaning in such cases and improve functional status.

Female↗
PubMed2001

Combination of preconditioning and delayed flap elevation: evidence for improved perfusion and oxygenation of the latissimus dorsi muscle for cardiomyoplasty.

BACKGROUND: Atrophy and fibrosis of the distal part of the latissimus dorsi muscle (LDM) wrap is a recognized complication of cardiomyoplasty that has been attributed to ischemia. Failure of the muscle wrap contributes to the late attrition seen in clinical cardiomyoplasty. In this study we examined the role of two-staged mobilization and of preconditioning by electrical stimulation on the regional perfusion and oxygenation of the LDM. METHODS: In a rabbit model (n = 36) the LDM was preconditioned as follows: group A muscles received preconditioning in situ; group B muscles were partially mobilized by dividing the intercostal perforators and then preconditioned; and group C muscles were completely mobilized and wrapped around a silicone-rubber mandrel before conditioning. Controls received no conditioning. The preconditioning regimen consisted of 2 weeks of continuous stimulation at 2.5 Hz. At completion of preconditioning the muscles were fully mobilized and mounted on a muscle-testing apparatus. Purpose-built microelectrodes measured regional PO2 and perfusion using a diffusible gas tracer technique. Muscles were weighed and processed for fiber typing and capillary counting. RESULTS: All preconditioned muscles demonstrated fiber transformation, with increased fatigue resistance. Perfusion of preconditioned muscles both at rest and during contraction was higher than control in the proximal part of the muscle. Distal regions of group B muscles had higher perfusion and capillary density than any other group (p < 0.05). Distal regions of group C had the lowest perfusion and capillary density, and showed muscle atrophy and histologic evidence of necrosis. During fatigue testing there was a decrease in the PO2 in the distal regions of the control and group C muscles (p < 0.05), whereas it was maintained at resting levels in both group A and B muscles. CONCLUSIONS: Conditioning in situ improves perfusion of the distal LDM and prevents a fall in tissue PO2 during contraction. Two-stage mobilization further improves distal perfusion and capillary density. In contrast, shortterm elevation followed by conditioning produces impaired distal perfusion, decrease in PO2, and fiber necrosis in the distal muscle. The present study suggests that partial mobilization of the LDM performed at the same time as placement of electrodes for preconditioning may prepare the LDM better for the demands of cardiomyoplasty.

Animals↗
PubMed2001

Clinical outcomes after aortic valve replacement with the Toronto stentless porcine valve.

BACKGROUND: Hemodynamic benefits of the Toronto stentless porcine valve have been documented. Clinical well-being and freedom from major valve-related events have been less well defined. METHODS: A total of 447 patients were prospectively followed for up to 8 years (1,745.2 valve years total, 3.9 valve years/patient). The patient demographics included 66% men, mean age 65 years, New York Heart Association functional class III-IV 55%, concomitant coronary artery bypass grafting 41%. RESULTS: We found that 83.7% of patients were in New York Heart Association functional class I and 80.8% had 0 to 1+ aortic insufficiency. Mean gradient at 6 years (n = 75) was 4.4 mm Hg and mean effective orifice area (EOA) 2.4 cm2. Late adverse event rates per patient per year were: embolism 1.0%, endocarditis 0.4%, thrombosis 0%, structural deterioration 0.2%, explant 0.3%, and valve-related death 0.6%. Freedom from valve-related death at 6 years was 95.8%; from cardiac death 96.3%. Freedom from endocarditis was 98.4%, from embolism 93.9%, from structural deterioration 97.4%, and freedom from explant 98.1%. For patients older than 60 years, freedom from structural deterioration was 100%. CONCLUSIONS: These results confirm satisfactory clinical outcomes after aortic valve replacement with the Toronto stentless porcine valve, with a low incidence of valve-related adverse events as long as 96 months after valve replacement.

Adult↗
PubMed2001

Improved reliability of post-operative ventricular pacing by use of bipolar temporary pacing leads.

The study compared the clinical reliability of using a bipolar epicardial wire (6495, Medtronic) over a unipolar type (FEP15, Ethicon) for post-operative pacing in coronary artery surgery. Atrial and ventricular wires of both types were implanted in 18 patients. Sensitivities and pacing thresholds were tested for 5 consecutive days. Results show that pacing thresholds were better maintained with the bipolar wire in both atria and ventricles. However, sensing failures were frequent in the atrial position (34% vs 9.3% compared with unipolar). By contrast, in the ventricle, no sensing failures occurred (0% vs 17.6% compared with unipolar). Furthermore, sensing magnitude was significantly better (11.13+/-1.32 vs 5.65+/-0.53 mV, P<0.001). We conclude that a single 6495 bipolar wire is effective for temporary ventricular pacing, whilst double unipolar wires remain a useful strategy for securing atrial sensing and pacing.

Cardiac Pacing, Artificial↗