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Christopher R Thompson

Publications and source records attributed to Christopher R Thompson.

At least 19 recordsLinked to original sources
PubMed2006

Six-month outcome of transapical transcatheter aortic valve implantation in the initial seven patients.

BACKGROUND: The current treatment of choice for symptomatic aortic stenosis is aortic valve replacement (AVR) with cardiopulmonary bypass (CPB), but AVR is associated with significant operative morbidity and mortality in elderly patients with multiple co-morbid conditions. We recently reported the first successful aortic valve implantation procedure (AVI) via a mini-thoracotomy and left ventricular apical puncture without cardiopulmonary bypass. We now report 6-month follow-up in our initial seven patients. METHODS: Seven patients (77+/-10 years old) with symptomatic aortic stenosis were deemed to be non-surgical candidates for AVR and not suitable for a transfemoral percutaneous heart valve implantation due to aorto-iliac disease. The predicted 30-day operative mortality was 31+/-23% according to logistic Euroscore. Patients underwent minimally invasive transapical AVI. With the guidance of fluoroscopy and transesophageal echocardiography, balloon predilation was followed by deployment of a 26mm Cribier-Edwardstrade mark valve (Edwards Lifesciences Inc., Irvine, CA) during rapid ventricular pacing to reduce forward flow and cardiac motion. RESULTS: Valve implantation was successful in all seven patients. There were no intra-procedural mortalities or complications. Thirty-day operative mortality was 14%. One patient died at day 12 due to pneumonia. Two patients died from non-cardiac diseases at day 51 and 85. The remaining four patients completed 6-month follow-up. The aortic valve area increased from 0.7+/-0.3 to 1.8+/-0.7 and 1.5+/-0.5cm(2) at 1 and 6 months, respectively. The mean transaortic gradient was reduced from 32+/-8 to 10+/-5 and 11+/-8mmHg at 1 and 6 months, respectively. Following AVI, none or trivial, mild, and moderate aortic regurgitation was observed in 4, 2, and 1 patients, respectively. There were no valve-related complications during the follow-up. CONCLUSION: Aortic valve implantation can successfully be performed via a minimally invasive apical approach without the need for cardiopulmonary bypass. The early results in this initial series are encouraging. This initial experience suggests that the minimally invasive transapical approach is a viable alternative for patients in whom open-heart surgery is not feasible or poses unacceptable risks.

Aged↗
PubMed2006

Transapical transcatheter aortic valve implantation in humans: initial clinical experience.

BACKGROUND: Aortic valve replacement with cardiopulmonary bypass is currently the treatment of choice for symptomatic aortic stenosis but carries a significant risk of morbidity and mortality, particularly in patients with comorbidities. Recently, percutaneous transfemoral aortic valve implantation has been proposed as a viable alternative in selected patients. We describe our experience with a new, minimally invasive, catheter-based approach to aortic valve implantation via left ventricular apical puncture without cardiopulmonary bypass or sternotomy. METHODS AND RESULTS: A left anterolateral intercostal incision is used to expose the left ventricular apex. Direct needle puncture of the apex allows introduction of a hemostatic sheath into the left ventricle. The valve prosthesis, constructed from a stainless steel stent with an attached trileaflet equine pericardial valve, is crimped onto a valvuloplasty balloon. The prosthetic valve and balloon catheter are passed over a wire into the left ventricle. Positioning within the aortic annulus is confirmed by fluoroscopy, aortography, and echocardiography. Rapid ventricular pacing is used to reduce cardiac output while the balloon is inflated, deploying the prosthesis within the annulus. Transapical aortic valve implantation was successfully performed in 7 patients in whom surgical risk was deemed excessive because of comorbidities. Echocardiographic median aortic valve area increased from 0.7 +/- 0.1 cm2 (interquartile range) to 1.8 +/- 0.8 cm2 (interquartile range). There were no intraprocedural deaths. At a follow up of 87 +/- 56 days, 6 of 7 patients remain alive and well. CONCLUSIONS: This initial experience suggests that transapical aortic valve implantation without cardiopulmonary bypass is feasible in selected patients with aortic stenosis.

Age Factors↗
PubMed2006

True versus reported waiting times for valvular aortic stenosis surgery.

OBJECTIVES: To produce a universally accepted waiting time definition for cardiovascular surgery, present the rationale for this definition, and compare data on current waiting times in British Columbia based on this definition versus the current definition in patients waiting for aortic stenosis surgery. STUDY DESIGN: The present study is a retrospective data analysis. SETTING: The fixed-dollar, single-payer health care delivery system in British Columbia. PATIENTS: All residents of British Columbia who were at least 22 years of age and who were placed on a waiting list for aortic valve surgery with the diagnosis of aortic stenosis between January 1, 1991, and December 31, 2000, were eligible for the present study. INTERVENTIONS: Dates of physician visits, procedures and surgery were obtained from the British Columbia Cardiac Registries and Medical Services Plan databases. True waiting times from physician visits to procedures and surgery were calculated. RESULTS: Of the 2516 patients booked for aortic valve surgery with a primary diagnosis of aortic stenosis, 2237 subjects (88.9%) were eligible for analysis after exclusions. The eligible patients ranged in age from 22 to 95 years, and 36.8% were female. The true median waiting time was 243 days (148 days [25th percentile], 397 days [75th percentile]), which was 3.2 times the interval currently reported as the waiting time (75 days [42, 127]). Thirty-nine patients died while waiting for surgery. Patients used more resources while waiting for surgery than after surgery. CONCLUSIONS: True waiting times for surgery for aortic stenosis in British Columbia are significantly longer than reported waiting times. The authors propose that the wait list time for cardiovascular surgery be redefined as "the time interval between the patient's first contact with a medical care provider with symptoms or signs which ultimately lead to cardiovascular surgery and the date of that surgery".

Adult↗
PubMed2006

Phospholipase D1 regulates phagocyte adhesion.

Adhesion is a fundamental cellular response that is essential to the physiologic processes of development, differentiation, proliferation, and motility, as well as to the pathology of inflammation, transformation, and metastasis. Adhesion of phagocytic leukocytes is a critical modulator of antimicrobial and cytotoxic functions, including the respiratory burst, secretion, and apoptosis. Because phospholipase D (PLD) is linked to several signaling pathways implicated in these processes, we tested the hypothesis that PLD regulates phagocyte adhesion. Adhesion of primary human neutrophils and monocyte-derived macrophages to fibronectin was accompanied by marked stimulation of PLD activity. Similarly, adhesion of both human (PLB, THP-1) and murine (RAW) myeloid-macrophage cell lines to fibronectin, fibrinogen, collagen, or plastic resulted in significant activation of PLD. Stimulation of PLD activity was rapid and persisted for at least 90 min. Confocal microscopy indicated that PLD1 exhibited partial colocalization with actin filaments at the adherent interface, in proximity to the focal adhesion protein, paxillin. Reductions in PLD activity by chemical inhibitors or specific short-interfering RNA-induced knockdown of PLD1 resulted in significant inhibition of phagocyte adhesion and was accompanied by reductions in total cellular F-actin. These data support the hypotheses that adhesion stimulates PLD activity, and that PLD1 regulates the initial stages of phagocyte adhesion. Stimulation of PLD activity may promote adhesion-dependent phagocyte effector responses.

Actins↗
PubMed2006

Percutaneous aortic valve implantation retrograde from the femoral artery.

BACKGROUND: Percutaneous aortic valve implantation by an antegrade transvenous approach has been described but is problematic. Retrograde prosthetic aortic valve implantation via the femoral artery has potential advantages. Percutaneous prosthetic aortic valve implantation via the femoral arterial approach is described and the initial experience reported. METHODS AND RESULTS: The valve prosthesis is constructed from a stainless steel stent with an attached trileaflet equine pericardial valve and a fabric cuff. After routine aortic balloon valvuloplasty, a 22F or 24F sheath is advanced from the femoral artery to the aorta. A steerable, deflectable catheter facilitates manipulation of the prosthesis around the aortic arch and through the stenotic valve. Rapid ventricular pacing is used to reduce cardiac output while the delivery balloon is inflated to deploy the prosthesis within the annulus. Percutaneous aortic prosthetic valve implantation was attempted in 18 patients (aged 81+/-6 years) in whom surgical risk was deemed excessive because of comorbidities. Iliac arterial injury, seen in the first 2 patients, did not recur after improvement in screening and access site management. Implantation was successful in 14 patients. After successful implantation, the aortic valve area increased from 0.6+/-0.2 to 1.6+/-0.4 cm2. There were no intraprocedural deaths. At follow-up of 75+/-55 days, 16 patients (89%) remained alive. CONCLUSIONS: This initial experience suggests that percutaneous transarterial aortic valve implantation is feasible in selected high-risk patients with satisfactory short-term outcomes.

Aged↗
PubMed2006

Percutaneous transvenous mitral annuloplasty: initial human experience with device implantation in the coronary sinus.

BACKGROUND: Mitral annuloplasty is the most common surgical procedure performed for ischemic mitral regurgitation (MR). Surgical mitral annuloplasty is limited by morbidity, mortality, and MR recurrence. We evaluated the safety and feasibility of a transvenous catheter-delivered implantable device to provide a percutaneous alternative to surgical mitral annuloplasty. METHODS AND RESULTS: Five patients with chronic ischemic MR underwent percutaneous transvenous implantation of an annuloplasty device in the coronary sinus. Implantation was successful in 4 patients. Baseline MR in the entire group was grade 3.0+/-0.7 and was reduced to grade 1.6+/-1.1 at the last postimplantation visit when the device was intact or the last postprocedural visit in the patient in whom the device was not successfully implanted. Separation of the bridge section of the device occurred in 3 of 4 implanted devices and was detected at 28 to 81 days after implantation. There were no postprocedural device-related complications. CONCLUSIONS: Percutaneous implantation of a device intended to remodel the mitral annulus is feasible. Initial experience suggests a possible favorable effect on MR. Percutaneous transvenous mitral annuloplasty warrants further evaluation as a less invasive alternative to surgical annuloplasty.

Aged↗
PubMed2006

Techniques for percutaneous closure of prosthetic paravalvular leaks.

Percutaneous transcatheter closure techniques are now routinely applied in the management of atrial and ventricular septal defects, patent ductus arteriosus, and other pathological cardiac and vascular communications. Recently, these same techniques have been applied to paravalvular defects. Reports are few; success variable and techniques vary widely. We review the current considerations and techniques of percutaneous transcatheter closure of paravalvular leaks.

Bioprosthesis↗
PubMed2006

Percutaneous closure of prosthetic paravalvular leaks: case series and review.

BACKGROUND: Paravalvular leaks (PVLs) are a well-recognized complication of prosthetic valve replacement. Most are asymptomatic and benign, but some may cause symptoms due to a large regurgitant volume or hemolysis. Medical therapy is palliative, while reoperation carries significant morbidity and mortality. Percutaneous transcatheter closure techniques, now routinely applied in the management of pathological cardiac and vascular communications, may be adaptable to PVL closure, potentially offer symptomatic relief. METHODS: We reviewed our experience with attempted percutaneous closure of PVLs, using data from medical and procedural records. RESULTS: Between 2001 and 2004, 14 procedures were performed in 10 patients, all under general anesthesia, with transesophageal and radiographic guidance. Mitral (9) and aortic (1) valve replacements were involved, both mechanical and bioprosthetic. A variety of devices were used, including atrial septal occluders, patent ductus arteriosus occluders, and coils (all of label use). Six had a single procedure, which was technically successful in four: in two, the PVL could not be crossed. Four underwent a second procedure, which was technically successful in three; in one the previously deployed device was dislodged necessitating urgent, but ultimately uneventful, surgical removal and leak repair. One patient had transient severe hemolysis, which resolved after 1 week. At 1-year follow-up (9/10 pts) three had died, five had sustained symptomatic improvement while 1 patient with a residual leak still required regular blood transfusions. CONCLUSIONS: Percutaneous closure of PVLs is time-consuming but feasible in selected patients, with a reasonable degree of technical and clinical success. A second procedure may be necessary and a variety of complications can occur.

Cardiac Catheterization↗
PubMed2006

Rapid pacing to facilitate transcatheter prosthetic heart valve implantation.

OBJECTIVES: We describe the technique of, and our experience with, rapid ventricular burst pacing to facilitate transcatheter heart valve implantation. BACKGROUND: Endovascular therapeutic procedures frequently require the precise placement of implantable devices. The precision of transcatheter device deployment may be hampered by cardiac motion or the effects of intravascular flow. Burst pacing is associated with a reduction in stroke volume, cardiac output, transvalvular flow, and cardiac motion. METHODS: Rapid pacing was used in 40 consecutive patients with severe aortic stenosis undergoing implantation of catheter-delivered prosthetic valves. Clinical, procedural, and hemodynamic records were reviewed. RESULTS: A mean of 5 +/- 2 burst pacing sequences at rates of 150-220 min(-) (1) were used during balloon valvuloplasty and valve deployment. The duration of pacing required during valve deployment was 12 +/- 3 sec. Pacing was relatively well tolerated when cautiously used with judicious recovery intervals and pressor support. Rapid pacing was associated with a rapid and effective reduction in systemic blood pressure, pulse pressure, transvalvular flow as well as cardiac and catheter motion. CONCLUSIONS: Rapid pacing is a relatively reliable technique to facilitate precise transcatheter deployment of prosthetic heart valves and other endovascular therapeutic devices.

Aged, 80 and over↗
PubMed2006

Percutaneous aortic valve implantation: a case report.

The present case demonstrates the percutaneous implantation of a bioprosthetic valve in a patient with severe aortic stenosis. An 85-year-old man with significant comorbidities was determined to be at unacceptable risk with traditional surgical valve replacement. Percutaneous aortic valve implantation was performed, was successful and uncomplicated, with significant clinical and hemodynamic improvement. Currently, this procedure is an option only for symptomatic patients who are not appropriate candidates for surgical valve replacement.

Aged, 80 and over↗
PubMed2005

Kidney function and mortality among patients with left ventricular systolic dysfunction.

Kidney disease has emerged as a risk factor for mortality in heart failure populations. The objective of this study was to determine the impact of different stages of kidney dysfunction (defined using the Kidney Disease Outcomes Quality Initiative [K/DOQI] classification system) and changes in kidney function on mortality in a cohort of patients with heart failure. A retrospective analysis was conducted of data from the randomized controlled trials Studies of Left Ventricular Dysfunction. A total of 6640 participants with asymptomatic and symptomatic heart failure were studied. Estimated GFR (eGFR) were calculated and then categorized according to the K/DOQI classification system into the following categories: > or =90, 60 to 89, 30 to 59, and 15 to 29 ml/min per 1.73 m2. Reduction in eGFR from baseline was calculated and subsequently categorized according to rate of decline (<5, 5 to 10, 11 to 15, and >15 ml/min per 1.73 m2 per year). Independent of baseline differences, lower levels of eGFR were associated with a higher total mortality compared with those with eGFR > or =90 ml/min (30 to 59 ml/min per 1.73 m2: hazard ratio [HR] 1.32, 95% confidence interval [CI] 1.10 to 1.59, P = 0.004; 15 to 29 ml/min per 1.73 m2: HR 2.54, 95% CI 1.54 to 4.19, P < 0.001). eGFR deteriorated rapidly (>15 ml/min per 1.73 m2 per year) in 12% of participants. This decline was associated with a significant increase in mortality compared with slower decline (<5 ml/min per 1.73 m2 per year), despite adjustments for baseline kidney function, baseline heart failure, or change in heart failure (HR 5.63; 95% CI 4.90 to 6.46; P < 0.0001). The levels of eGFR from the K/DOQI classification system are associated with mortality in a well-characterized heart failure population. Rate of decline in kidney function is a strong predictor of increased mortality in this population, independent of worsening heart failure and baseline kidney function.

Adult↗
PubMed2005

Prognostic value of troponin T and I among asymptomatic patients with end-stage renal disease: a meta-analysis.

BACKGROUND: The prognostic usefulness of troponin enzymes in end-stage renal disease (ESRD) patients is controversial. To resolve this uncertainty of troponin as a prognostic tool, we conducted a systematic review to quantify the association between elevated troponin I or T and long-term total mortality among ESRD patients not suspected of having acute coronary syndrome. METHODS AND RESULTS: We conducted an unrestricted search from the MEDLINE, EMBASE, and DARE bibliographic databases to December 2004 using the terms troponin.mp. or exp troponin and exp kidney, exp renal, exp kidney disease exp renal replacement therapy. We also manually searched review articles and bibliographies to supplement the search. Studies were included if they were prospective observational studies, used cardiac-specific troponin assays, and evaluated long-term risk of death or cardiac events for asymptomatic ESRD patients. Two authors independently abstracted data on study and patient characteristics. Studies findings were stratified according to troponin T or I levels. We used a random-effects model to pool study results and tested for heterogeneity using chi2 testing and used funnel-plot inspection to evaluate the presence of publication bias. Data from 28 studies (3931 patients) published between 1999 and December 2004 were included in this review. Patients received dialysis for a median duration of 4 years, with a mean follow-up of 23 months. From the pooled analysis, elevated troponin T (>0.1 ng/mL) was significantly associated with increased all-cause mortality (relative risk, 2.64; 95% CI, 2.17 to 3.20). Although the prognostic effect sizes were all consistent with a positive relationship between troponin T and mortality, there was significant heterogeneity in the magnitude of these effect sizes (P=0.015). The funnel plot showed evidence of publication bias. Elevated troponin T was also strongly associated with increased cardiac death. Studies evaluating troponin I included a wide variety of assays and differing cut points, rendering synthesis of the study findings difficult. CONCLUSIONS: Elevated troponin T (>0.1 ng/mL) identifies a subgroup of ESRD patients who have poor survival and a high risk of cardiac death despite being asymptomatic. These findings suggest that troponin T is a promising risk stratification tool and may help frame therapeutic decisions. The clinical interpretation of elevated troponin I levels, however, remain unclear, largely because of the lack of standardization of assays.

Biomarkers↗
PubMed2005

A clinical prediction rule for early discharge of patients with chest pain.

STUDY OBJECTIVE: Current risk stratification tools do not identify very-low-risk patients who can be safely discharged without prolonged emergency department (ED) observation, expensive rule-out protocols, or provocative testing. We seek to develop a clinical prediction rule applicable within 2 hours of ED arrival that would miss fewer than 2% of acute coronary syndrome patients and allow discharge within 2 to 3 hours for at least 30% of patients without acute coronary syndrome. METHODS: This prospective, cohort study enrolled consenting eligible subjects at least 25 years old at a single site. At 30 days, investigators assigned a diagnosis of acute coronary syndrome or no acute coronary syndrome according to predefined explicit definitions. A recursive partitioning model included risk factors, pain characteristics, physical and ECG findings, and cardiac marker results. RESULTS: Of 769 patients studied, 77 (10.0%) had acute myocardial infarction and 88 (11.4%) definite unstable angina. We derived a clinical prediction rule that was 98.8% sensitive and 32.5% specific. Patients have very low risk of acute coronary syndrome if they have a normal initial ECG, no previous ischemic chest pain, and age younger than 40 years. In addition, patients at least 40 years old and with a normal ECG result, no previous ischemic chest pain, and low-risk pain characteristics have very low risk if they have an initial creatine kinase-MB (CK-MB) less than 3.0 microg/L or an initial CK-MB greater than or equal to 3.0 microg/L but no ECG or serum-marker increase at 2 hours. CONCLUSION: The Vancouver Chest Pain Rule for early discharge defines a group of patients who can be safely discharged after a brief evaluation in the ED. Prospective validation is needed.

Adult↗
PubMed2005

Sphingosine kinase 1 (SK1) is recruited to nascent phagosomes in human macrophages: inhibition of SK1 translocation by Mycobacterium tuberculosis.

Mycobacterium tuberculosis (M.tb) is a leading cause of global infectious mortality. The pathogenesis of tuberculosis involves inhibition of phagosome maturation, leading to survival of M.tb within human macrophages. A key determinant is M.tb-induced inhibition of macrophage sphingosine kinase (SK) activity, which normally induces Ca2+ signaling and phagosome maturation. Our objective was to determine the spatial localization of SK during phagocytosis and its inhibition by M.tb. Stimulation of SK activity by killed M.tb, live Staphylococcus aureus, or latex beads was associated with translocation of cytosolic SK1 to the phagosome membrane. In contrast, SK1 did not associate with phagosomes containing live M.tb. To characterize the mechanism of phagosomal translocation, live cell confocal microscopy was used to compare the localization of wild-type SK1, catalytically inactive SK1G82D, and a phosphorylation-defective mutant that does not undergo plasma membrane translocation (SK1S225A). The magnitude and kinetics of translocation of SK1G82D and SK1S225A to latex bead phagosomes were indistinguishable from those of wild-type SK1, indicating that novel determinants regulate the association of SK1 with nascent phagosomes. These data are consistent with a model in which M.tb inhibits both the activation and phagosomal translocation of SK1 to block the localized Ca2+ transients required for phagosome maturation.

Biological Transport, Active↗
PubMed2005

Cardiogenic shock: predictors of outcome based on right and left ventricular size and function at presentation.

OBJECTIVE: To determine the characteristics and prognostic importance of right ventricular (RV) dilatation and dysfunction in patients with cardiogenic shock secondary to left ventricular (LV) dysfunction enrolled in the Should we emergently revascularize occluded coronaries for cardiogenic shock (SHOCK) trial. METHODS: LV and RV size and function were quantified by echocardiography in 99 patients with cardiogenic shock secondary to predominant LV dysfunction. RESULTS: For all patients, RV dysfunction was not associated with a poor 1-year survival. When the 59 patients with RV dysfunction were stratified into two morphologic groups based upon LV-to-RV end-diastolic area ratio (LV/RV) < or >or=2, the presence of disproportionate RV enlargement (LV/RV <2) was associated with inferior myocardial infarction (80%) and right coronary artery culprit disease (79%). In contrast, the index myocardial infarction in patients with predominant LV enlargement (LV/RV >or=2) was anterior (69%) and associated with left anterior descending artery disease (64%). Patients with LV/RV <2 had significantly higher right atrial pressures (20.1+/-5.2 compared with 14.5+/-8.9 mmHg, P=0.001) and lower RV fractional area change (20.4+/-8.7 compared with 33.5+/-11.0%, P=0.0001), heart rate (87+/-21 compared with 106+/-23 beats/min, P=0.006) and cardiac index (1.5+/-0.5 compared with 2.0 +/-0.9 l/min per m, P=0.007) than patients with LV/RV >or=2. Despite the hemodynamic profile and severity of RV dysfunction in the LV/RV <2 group, 12-month survival was significantly greater in these patients (70% LV/RV <2 compared with 34% LV/RV >or=2, P=0.027). CONCLUSIONS: In patients with cardiogenic shock secondary to predominant LV failure, the presence of RV dilatation and dysfunction identifies a subgroup of patients with predominant inferior myocardial infarction and an improved long-term prognosis.

Aged↗
PubMed2004

Safety and efficiency of emergency department assessment of chest discomfort.

BACKGROUND: Most Canadian emergency departments use an unstructured, individualized approach to patients with chest pain, without data to support the safety and efficiency of this practice. We sought to determine the proportions of patients with chest discomfort in emergency departments who either had acute coronary syndrome (ACS) and were inappropriately discharged from the emergency department or did not have ACS and were held for investigation. METHODS: Consecutive consenting patients aged 25 years or older presenting with chest discomfort to 2 urban tertiary care emergency departments between June 2000 and April 2001 were prospectively enrolled unless they had a terminal illness, an obvious traumatic cause, a radiographically identifiable cause, severe communication problems or no fixed address in British Columbia or they would not be available for follow-up by telephone. At 30 days we assigned predefined explicit outcome diagnoses: definite ACS (acute myocardial infarction [AMI] or definite unstable angina) or no ACS. RESULTS: Of 1819 patients, 241 (13.2%) were assigned a 30-day diagnosis of AMI and 157 (8.6%), definite unstable angina. Of these 398 patients, 21 (5.3%) were discharged from the emergency department without a diagnosis of ACS and without plans for further investigation. The clinical sensitivity for detecting ACS was 94.7% (95% confidence interval [CI] 92.5%- 96.9%) and the specificity 73.8% (95% CI 71.5%- 76.0%). Of the patients without ACS or an adverse event, 71.1% were admitted to hospital or held in the emergency department for more than 3 hours. INTERPRETATION: The current individualized approach to evaluation and disposition of patients with chest discomfort in 2 Canadian tertiary care emergency departments misses 5.3% of cases of ACS while consuming considerable health care resources for patients without coronary disease. Opportunities exist to improve both safety and efficiency.

Adult↗