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Biomedical subjects

S Westaby

Publications and source records attributed to S Westaby.

At least 37 records · Page 2Linked to original sources
PubMed2001

Midterm survival of stented versus stentless valves: does concomitant coronary artery bypass grafting impact survival?

The purpose of this study was to examine the impact of concomitant coronary artery bypass grafting (CABG) and valve design on survival following aortic valve replacement (AVR) with stentless and stented bioprostheses. Survival data for 1798 patients undergoing AVR between 1991 and 1997 with either a stentless (Medtronic Freestyle = 700, Toronto SPV = 447; N = 1147) or stented (Hancock II = 224, Carpentier-Edwards SAV = 427; N = 651) valve were analyzed. Bivariable analyses using Kaplan-Meier survival curves and log-rank test were performed to compare survival probabilities by valve type. Multivariable stepwise Cox's proportional hazard models were used to control for potentially confounding variables. Concomitant CABG was performed in 41% of stentless and 46% of stented patients (P =.04). Survival probability at 5 years was 0.84 (95% CI = 0.81, 0.87) for stentless versus 0.79 (95% CI = 0.75, 0.83) for stented patients (P =.004). In the absence of concomitant CABG, survival was superior in stentless (0.84) over stented (0.80) patients, but these differences were not statistically significant (P =.053). In patients that underwent AVR with concomitant CABG, survival was significantly better in stentless patients (0.82) than in stented individuals (0.77, P =.049). The unadjusted hazard ratio for stented versus stentless was 1.44 (95% CI = 1.12, 1.86, P =.005). In the final Cox's proportional hazard model the variables that effected survival were valve type and age in decades. New York Heart Association class at the time of surgery had a marginal effect on survival. The data demonstrate improved midterm survival with stentless versus stented valves. Subgroup analysis suggests survival benefits of stentless valves may be greater in patients who undergo concomitant CABG surgery.

Aged↗
PubMed2000

First permanent implant of the Jarvik 2000 Heart.

BACKGROUND: Heart failure is a major public-health concern. Quality and duration of life on maximum medical therapy are poor. The availability of donor hearts is severely limited, therefore an alternative approach is necessary. We have explored the use of a new type of left-ventricular assist device intended as a long-term solution to end-stage heart failure. METHODS: As part of a prospective clinical trial, we implanted the first permanent Jarvik 2000 Heart--an intraventricular device with an innovative power delivery system--into a 61-year-old man (New York Heart Association functional class IV) with dilated cardiomyopathy. We assessed the effect of this left-ventricular assist device on both native heart function and the symptoms and systemic characteristics of heart failure. FINDINGS: The Jarvik 2000 Heart sustained the patient's circulation, and was practical and user-friendly. After 6 weeks, exercise tolerance, myocardial function, and end-organ function improved. Symptoms of heart failure have resolved, and continuous decreased pulse-pressure perfusion has had no adverse effects in the short term. There has been no significant haemolysis and no device-related complications. The skull-mounted pedestal is unobtrusive and has healed well. CONCLUSIONS: The initial success of this procedure raises the possibility of a new treatment for end-stage heart failure. In the longer term, its role will be determined by mechanical reliability.

Blood Pressure↗
PubMed2000

Mediastinal false aneurysm after thoracic aortic surgery.

BACKGROUND: Postoperative mediastinal false aneurysm is associated with a substantial morbidity and mortality. Surgical treatment is mandatory, although the individual approach varies according to the type of pathologic process, infection status, and site of origin of the aneurysm. METHODS: Between April 1993 and February 1999, we treated 10 patients, aged 25 to 73 years, with anastomotic mediastinal false aneurysm originating from the proximal thoracic aorta. Nine had undergone prior operations on the ascending aorta (7, type A dissection repair; 1, aortitis; 1, root abscess) with a Dacron conduit (n = 5) or valved conduit (n = 4). The last patient had undergone valve replacement for excavating aortic root sepsis. False aneurysms were detected from 2 to 70 months after the most recent operation. Three patients had positive tissue cultures. The surgical procedure was direct suture repair of the disrupted anastomosis in 5, root or ascending aortic replacement with an aortic homograft in 4, and Dacron graft interposition in 1. Hypothermic low-flow perfusion with or without circulatory arrest was used in all patients. RESULTS: There was one hospital death caused by staphylococcal mediastinitis. A false aneurysm recurred after direct suture repair in 2 patients with underlying type A dissection or aortitis. This resulted in one late death. One patient experienced a neurologic event during removal of an infected vascular graft. All 8 surviving patients are alive and well after a mean follow-up of 2 years. Three patients with mycotic false aneurysms remain free from infection after aortic homograft replacement. CONCLUSIONS: Mediastinal false aneurysms are surgically taxing. Low-flow hypothermic perfusion with or without circulatory arrest allows safe reentry. Radical surgery provides a satisfactory outcome in infected patients. Local repair of suture dehiscence in pathologic tissues may predispose to recurrence. We suspect that excessive use of formalin in gelatin-resorcin-formol glue may predispose to tissue necrosis.

Adult↗
PubMed2000

Mechanical bridge to recovery in fulminant myocarditis.

A patient with acute fulminant lymphocytic myocarditis and cardiogenic shock was successfully treated by mechanical off loading of the left ventricle. A nonpulsatile left-heart bypass was undertaken with an implantable centrifugal blood pump. Careful weaning resulted in device removal on the seventh day. Left and right ventricular function is sustained at 7 months. Widespread application of this method depends on the availability of an inexpensive user friendly blood pump, appropriate weaning protocols and emerging strategies to promote sustainable myocardial recovery.

Adult↗
PubMed2000

Survival advantage of stentless aortic bioprostheses.

BACKGROUND: Bioprostheses (BPs) are used to avoid anticoagulation after aortic valve replacement (AVR) in patients over 65 years of age. Stentless BPs offer established hemodynamic benefits. We sought to determine whether these advantages translate into improved survival. METHODS: Between 1993 and 1997, follow-up data (for Food and Drug Administration submission) were collected prospectively for 160 consecutive, unselected hospital survivors who received the Freestyle valve (FS). Equivalent data were collected for 247 Carpentier-Edwards (CE) porcine xenograft patients. Detailed comparative statistical analysis was used to compare events and survival between the groups. Follow-up was 100% complete for the FS (5.2 years maximum; mean 3.2+/-1.0 years) group and 98% (7.2 years maximum; mean 3.8+/-2.0 years) for CE. RESULTS: The groups were well matched in age (FS, 73+/-6 years; CE, 74+/-6 years), gender (FS, 58% male; CE, 62% male), ventricular function, and number of patients requiring coronary grafts (FS, 41%; CE, 37%). Actuarial survival at 5 years was 84% for FS versus 69% for CE (p = 0.023 Kaplan Meier, p = 0.009 Cox). Annual mortality rates were 3.6% for FS versus 7.1% for CE (p = 0.001). Thromboembolic rate was 0.8% per year for FS and 2.4% for CE (p = 0.024) without a difference in cardiac rhythm. Incidence of nonstructural dysfunction (paravalvular leak) was 0.2% for FS versus 1.3% for CE (p = 0.020). CONCLUSIONS: By 5 years, the stentless valve patients had improved survival and reduced adverse events. Though differences in durability are yet to be proved, our findings support the use of stentless bioprostheses in this age group.

Adult↗
PubMed2000

Is there a relationship between serum S-100beta protein and neuropsychologic dysfunction after cardiopulmonary bypass?

OBJECTIVES: Over the past decade, the glial protein S-100beta has been used to detect cerebral injury in a number of clinical settings including cardiac surgery. Previous investigations suggest that S-100beta is capable of identifying patients with cerebral dysfunction after cardiopulmonary bypass. Whether detection of elevated levels S-100beta reflects long-term cognitive impairment remains to be shown. The present study evaluated whether perioperative release of S-100beta after coronary artery operations with cardiopulmonary bypass could predict early or late neuropsychologic impairment. METHODS: A total of 100 patients undergoing elective coronary bypass without a previous history of neurologic events were prospectively studied. To exclude noncerebral sources of S-100beta, we did not use cardiotomy suction or retransfusion of shed mediastinal blood. Serial perioperative measurements of S-100beta were performed with the use of a new sensitive immunoluminometric assay up to 8 hours after the operation. Patients underwent cognitive testing on a battery of 11 tests before the operation, before discharge from the hospital, and 3 months later. RESULTS: No significant correlation was found between S-100beta release and neuropsychologic measures either 5 days or 3 months after the operation. CONCLUSION: Despite using a sensitive immunoluminometric assay of S-100beta, we found no evidence to support the suggestion that early release of S-100beta may reflect long-term neurologic injury capable of producing cognitive impairment.

Anesthesia, General↗
PubMed2000

Aortic root replacement with coronary button re-implantation: low risk and predictable outcome.

OBJECTIVE: Cardiac morbidity in aortic root replacement often occurs through myocardial ischaemia. We analyzed a 10 year experience of all root replacement operations by one surgeon to determine the incidence of coronary complications and risk factors for early mortality. METHODS: The study included 140 aortic root replacement patients (aged from 2 to 77 years; median 53 years) operated between 1988 and 1999. Thirty-four had Marfan's syndrome. Eleven had root infection requiring homograft replacement. Nineteen were reoperations (14%). Concomitant procedures were arch replacement (16), mitral replacement (five), and coronary bypass (22). Mobilization and reimplantation of the coronary ostia was performed in 139 patients. We performed the distal graft anastomosis before right coronary reimplantation. RESULTS: There were eight hospital deaths (5.7%). Risk factors for hospital mortality were: preoperative NYHA class IV, shock, LVEF < or =30%, acute dissection, concomitant mitral valve replacement, pump time > or = 60 min, reentry for bleeding, and postoperative renal failure. Neither myocardial ischaemia nor right ventricular dysfunction contribute to mortality. There were 18 late deaths with an actuarial survival of 79% at 5 years. There were no late coronary false aneurysms. CONCLUSIONS: Button reimplantation with the sequence described is predictable and safe. Wrap-around is unnecessary. Coronary aneurysms have been eliminated.

Actuarial Analysis↗
PubMed2000

Commentary

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Journal Article↗
PubMed1999

Medium-term determinants of left ventricular mass index after stentless aortic valve replacement.

BACKGROUND: This study aimed to investigate the risk factors for elevated left ventricular mass index 3 to 5 years after stentless aortic valve replacement, and to elucidate the underlying physiologic mechanisms. METHODS: Eighty-nine patients (age, 76 +/- 6 years, 51 males) having a stentless porcine valve for aortic stenosis (n = 76) or regurgitation (n = 13) were prospectively studied by Doppler echocardiography 3 to 5 years after operation. Left ventricular systolic function, mass index, blood pressure, cardiac rhythm, and New York Heart Association function class were all determined. Stentless valve effective orifice area, mean pressure drop, and the presence and degree of aortic regurgitation were quantified. RESULTS: The mean stentless aortic valve size was 24 +/- 2 mm. At follow-up time of 45 +/- 9 months, effective orifice area index was 1.2 +/- 0.35 cm2 x m(-2), and mean pressure drop was 5.7 +/- 3.8 mm Hg. Left ventricular mass index was 128 +/- 47 g x m(-2), and ejection fraction was 63% +/- 14%. Multivariant analysis showed a greater left ventricular mass index to be associated with nonsinus rhythm (versus sinus) (163 +/- 8 versus 131 +/- 7 g x m(-2)), greater pulse pressure (> 84 mm Hg) (161 +/- 7 versus 133 +/- 7 g x m(-2)), New York Heart Association class II or III (versus class I) (166 +/- 10 versus 128 +/- 5 g x m(-2)), and male sex (versus female) (160 +/- 7 versus 134 +/- 8 g x m(-2)), all p < 0.01. Mean pressure drop (> 8 mm Hg), effective orifice area index (< 1.0 cm2 x m(-2)), the presence of mild regurgitation of the stentless valve, or the type of previous valve disease were insignificant determinants of left ventricular mass index. CONCLUSIONS: Three to five years after the implantation, stentless aortic valve hemodynamics remain excellent. Left ventricular hypertrophy caused by previous native aortic valve disease had largely regressed. However, patient-related factors, particularly systemic blood pressure, cardiac rhythm, and function, are significant causes of late residual left ventricular hypertrophy. Thus, continued medical care and earlier surgical intervention may further improve the outlook for these patients.

Aged↗
PubMed1999

Coronary reimplantation in aortic root replacement: a method to avoid tension.

We describe a technique to relieve tension on the reimplanted right coronary button during aortic root replacement. A hood is fashioned from autogenous aorta or pericardium to provide a funnel inflow to the coronary ostium. The technique can be used either electively or as a rescue maneuver in the event of right ventricular ischemia.

Aorta↗
PubMed1999

Operation of mid-arch coarctation.

BACKGROUND: Coarctation occurring within the aortic arch is rare and may present difficulties during surgical repair. We describe the operative technique and outcome in 6 patients with this unusual anomaly. METHODS: Five patients had antegrade perfusion with circulatory arrest. Three patients with presubclavian narrowing (one presenting with type B dissection) were operated through extended left thoracotomy. Two precarotid and paracarotid lesions were approached through a median sternotomy. All patients were perfused antegradely from the ascending aorta and operated with hypothermic circulatory arrest. One patient who had a complex presubclavian coarctation after two previous repairs received an ascending aorta to abdominal aorta bypass graft without cardiopulmonary bypass. RESULTS: All patients survived operation and are well at a mean follow-up of 3.3 years after the procedure. None had cerebral problems or spinal cord injury. Renal function was unchanged. The mean (+/- standard error of the mean) resting gradient across the coarctation decreased from 42+/-4.0 mm Hg to 6+/-1.2 mm Hg (p = 0.0004). CONCLUSIONS: Hypothermic circulatory arrest using antegrade ascending aortic perfusion allows safe and effective repair of mid-arch coarctation. Complicated reoperations can be managed safely using ascending-to-abdominal aortic bypass.

Adolescent↗
PubMed1999

Anti-fibrinolytic therapy in thoracic aortic surgery.

BACKGROUND: Bleeding is an important cause of morbidity in thoracic aortic surgery. METHODS: We reviewed the mechanisms for fibrinolysis in aortic surgery and the propensity for intervention. Several studies have addressed the safety and efficacy of aprotinin. RESULTS: The endothelium regulates the balance between thrombosis and fibrinolysis. During hypothermic circulatory arrest, thrombin generation stimulates protein C production and tissue plasminogen activator release to promote fibrinolysis. Hypothermia also adversely affects platelet function and coagulation. Controversy exists regarding the effectiveness and dangers of antifibrinolytic agents after circulatory arrest. CONCLUSIONS: Fibrinolysis remains problematic during thoracic aortic aneurysm surgery. Heparin management is complicated by aprotinin and insufficient heparin may result in thrombotic events. Aprotinin is safe during rewarming or postoperatively.

Antifibrinolytic Agents↗
PubMed1999

Aortic dissection in Marfan's syndrome.

BACKGROUND: Aortic dissection is the most frequent cause of premature death in Marfan's syndrome. Low-risk elective surgery of the abnormal aortic root has the potential to prevent this complication. METHODS: We examine genetic, structural, and pathophysiological mechanisms of aortic dissection and discuss the surgical methods used when dissection occurs. RESULTS: Abnormal fibrillin disturbs the functional relationship between blood flow and vascular endothelial cell response (mechanotransduction). Decreased arterial distensibility also decreases aortic wall stress, thereby predisposing to dissection in the weakened arterial wall. Radical root and wall surgery and lifelong beta-blockade are required after aortic dissection. CONCLUSIONS: Detailed lifelong medical and surgical treatment can greatly prolong life in Marfan's syndrome. Elective aortic root replacement is paramount in preventing aortic dissection and avoiding subsequent problems in the distal aorta.

Aortic Dissection↗
PubMed1999

Serum S100B and hypothermic circulatory arrest in adults.

BACKGROUND: Cerebral injury is the most important complication of cardiac operations with cardiopulmonary bypass. Prolonged total circulatory arrest (TCA) can expose patients to an even greater risk of cerebral injury. We sought to detect the degree of cerebral injury in adults who had thoracic aortic operations with TCA by measuring S100B protein, which is released into the circulation after cerebral injury. METHODS: Serial measurements of S100B protein, a highly specific serum marker of astroglial damage, were performed in 26 patients who had complex aortic operations, of whom 13 required cardiopulmonary bypass alone (for aortic root replacement), and in 13 patients who required an additional period of TCA (for type A aortic dissections and arch aneurysms). Blood samples were taken preoperatively, at skin closure, and 5 and 24 hours postoperatively. RESULTS: There were significant increases in serum S100B concentrations in all patients, and peak levels occurred at skin closure. The magnitude of the increase in S100B was significantly greater at all postoperative time points and persisted longer in the TCA group. There was a significant correlation between the duration of the TCA and S100B concentration at 5 hours (r = 0.66, p = 0.01) and 24 hours (r = 0.63, p = 0.02) postoperatively. CONCLUSIONS: S100B levels were higher in all patients who had complex aortic operations and were significantly greater in patients requiring a period of TCA. The duration of the TCA period correlated with S100B levels 5 hours and at 24 hours postoperatively. Circumstantial evidence, in accordance with other studies, suggests that S100B protein is a marker for cerebral injury during cardiac operations.

Adult↗