Biomedical subjects

John R Pepper

Publications and source records attributed to John R Pepper.

5 recordsLinked to original sources

PubMed2003

Is the use of cardiopulmonary bypass for multivessel coronary artery bypass surgery an independent predictor of operative mortality in patients with ischemic left ventricular dysfunction?

BACKGROUND: l Coronary artery bypass grafting for patients with ischemic left ventricular dysfunction (ILVD) remains superior to medical therapy in terms of long-term survival. Recently, off-pump coronary artery bypass surgery has been shown to be very promising in achieving functional improvements with favorable operative mortality in this challenging group of patients. The aim of this study was to assess the risk factors responsible for operative mortality in this group of patients. METHODS: The records of 305 consecutive ILVD patients, who underwent primary isolated coronary artery bypass grafting for multivessel disease at The National Heart and Lung Institute, Imperial College, University of London, between January 1999 and January 2002, were reviewed retrospectively. Patients were considered to have ILVD if they had a left ventricular ejection fraction of 0.30 or less on preoperative coronary angiography. One hundred six patients were operated on using the off-pump coronary artery bypass surgery technique, and 199 patients were operated on using the conventional coronary artery bypass grafting technique with cardiopulmonary bypass. RESU;TS: Seven (6.6%) patients died in the off-pump coronary artery bypass surgery group, whereas 28 (14.1%) patients died in the cardiopulmonary bypass group (p = 0.05). Univariate analysis of all the preoperative characteristics was performed to identify the potential predictors of mortality in the whole group of ILVD patients. Potential predictors of mortality included symptom status (stable/unstable), chronic obstructive airway disease, dyspnea grade III and IV on the New York Heart Association classification, intravenous nitrates, preoperative use of intraaortic balloon pump, ventricular tachycardia or ventricular fibrillation, body surface area less than 2, and cardiopulmonary bypass. Only ventricular tachycardia or ventricular fibrillation was proved to act as an independent predictor of operative mortality in this group of ILVD patients, with an odds ratio of 29.6 (95% confidence interval, 8.9 to 98). CONCLUSIONS: This study showed that using cardiopulmonary bypass for multivessel coronary artery bypass grafting in patients with ILVD was not proved to act as an independent predictor of operative mortality.

Aged↗

PubMed2003

Intra-aortic balloon pumping: effects on left ventricular diastolic function.

OBJECTIVE: The intra-aortic balloon pump is the most widely used form of temporary cardiac assist and often utilised in patients before and after cardiac surgery. Several effects of balloon counter-pulsation have been reported previously, but its effect on left ventricular diastolic function has not been thoroughly investigated. The aim of this study is to examine the effect of the intra-aortic balloon pump on left ventricular wall motion and transmitral flow. METHODS: We studied 20 patients in the intensive care unit, less than 36 h following cardiac surgery. We recorded left anterior descending coronary artery and transmitral E-wave flow velocities using transesophageal echocardiography pulsed Doppler. We also recorded left ventricular long axis free-wall movement using M-mode. The intra-aortic balloon pump was set to full augmentation and recordings were made at pumping cycles 1:1, 1:2, 1:3, and when the pump was on stand-by, leaving a minimum of 5 min between the pumping modes to allow the return to control conditions. In order to eliminate time effects, the sequence of recording was varied between patients using a 4 by 4 Latin-square. RESULTS: The peak diastolic left anterior descending coronary artery and transmitral E-wave flow velocities, and left ventricular free-wall early diastolic lengthening velocity increased significantly with intra-aortic balloon pumping cycles 1:1, 1:2 and 1:3 compared to their value with the pump on stand-by, all P < 0.001. The increase in peak transmitral E-wave flow velocity correlated with the increase in peak left anterior descending coronary artery diastolic flow velocity (r = 0.74, P = 0.02), and with the increase in left ventricular free-wall early diastolic lengthening velocity (r = 0.80, P < 0.001). CONCLUSION: Using the intra-aortic balloon pump post-cardiac surgery significantly increases peak diastolic left anterior descending coronary artery flow velocities and left ventricular free-wall early diastolic lengthening velocity, whose increase explains the increase in peak transmitral E-wave velocity. Although coronary flow is epicardial and mitral flow is intracardial, their close relationship suggests an improvement in left ventricular diastolic function with intra-aortic balloon pump.

Aged↗

PubMed2003

Correlation between thrombin potential and bleeding after cardiac surgery in adults.

We used a sensitive assay to measure thrombin potential in 20 patients who underwent cardiopulmonary bypass surgery for coronary artery bypass grafts. We measured coagulation factors II, V, VII, VIII and X. Blood loss was measured as the total amount in the mediastinal drains in the first 24 h postoperatively. Thrombin potential was median 107 nmol/l.min (range 62-181) preoperatively and median 46 nmol/l.min (range 19-120) postoperatively. Coagulation factors II, V, VII,VIII and X were within normal limits preoperatively. Factor II fell from 77 IU/dl preoperatively to 37 IU/dl at 120 min postoperatively. Factor V fell from 85 IU/dl preoperatively to 61 IU/dl postoperatively. Factor VII fell from 91 IU/dl to 66 IU/dl postoperatively. Factor VIII was 128 IU/dl preoperatively and 127 IU/dl postoperatively. Factor X fell from 90 IU/dl preoperatively to 50 IU/dl postoperatively. Total blood loss in 24 h in the mediastinal drains postoperatively was mean 673 ml, median 650 ml (range 250-2000). Reduction in thrombin potential correlated inversely with postoperative blood loss, r= -0.75 (Spearman correlation). The fall in the thrombin potential correlated with the prothrombin level (r = 0.75) and factor X (r = 0.47).

Aged↗

PubMed2002

Cytokine modulation of granulocyte macrophage-CSF and granulocyte-CSF release from stimulated vascular smooth muscle cells.

Cytokine-stimulated vascular smooth muscle cells release the colony-stimulating factors (CSFs) granulocyte macrophage-CSF and granulocyte-CSF. We have investigated the effects of a range of cytokines on the release of CSFs from human vascular smooth muscle cells stimulated with interleukin-1beta. Interleukin-4 suppressed granulocyte macrophage-CSF release but potentiated granulocyte-CSF release; interferon-gamma inhibited the release of both, whilst interleukin-5 had no effect. Both interleukin-10 and interleukin-13 inhibited granulocyte macrophage-CSF release but did not affect granulocyte-CSF release. The ability of individual cytokines to differentially modulate CSFs has profound consequences for the populations of leukocytes present at the site of inflammation.

Cells, Cultured↗

PubMed2002

Do stentless valves make a difference?

Stentless glutaraldehyde-preserved bioprosthetic valves for the aortic position were introduced into clinical practice in 1988. Their introduction coincided with the publication of several long-term observational studies of aortic homografts, which showed superior freedom from structural valve damage compared to the first generation stented porcine bioprosthesis. There followed 10 years of intensive investigation into the haemodynamic characteristics of stentless valves. These studies have demonstrated superior haemodynamic features in terms of transvalvular pressure gradients, effective orifice area, and more complete regression of left ventricular hypertrophy. Despite these advantages, stentless valves have yet to be adopted widely. This review seeks to explain this paradox.

Aortic Valve Stenosis↗