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Biomedical subjects

F Wellens

Publications and source records attributed to F Wellens.

At least 37 records · Page 2Linked to original sources
PubMed1997

The value of DDD pacing in patients with an implantable cardioverter defibrillator.

Although the beneficial effects of DDD pacing are well known, currently available ICDs provide only fixed rate ventricular antibradycardia pacing. In a consecutive series of 139 patients with ICDs, we have analyzed the need for antibradycardia pacing and the indications for DDD pacing. We also report our initial experience with the Defender 9001 (ELA Medical, France) DDD-ICD. Out of 139 patients, 25 (18%) were in need of antibradycardia pacing. Ten patients already had a pacemaker at the time of ICD implantation and ten other patients had a conventional pacemaker indication at that time. Five patients became pacemaker dependent during a follow-up of 20 +/- 8 months. The disorders necessitating pacemaker therapy were high degree AV conduction disturbances in 72%, sick sinus syndrome in 12%, and AF with a slow ventricular response in 16% of patients. Based upon current indications, DDD pacing was indicated in 20 (80%) of 25 patients. The Defender 9001 DDD-ICD (ELA Medical) was used in two patients with ischemic cardiomyopathy and pacemaker syndrome with VVI pacing. Cardiac output during DDD pacing increased by 36% in one patient with an increase in VO2 max during exercise of 29%. The other patient showed an increase in cardiac output of 50% with DDD pacing, and, while unable to exercise with VVI pacing, had a VO2max of 24 mL/kg per minute during DDD pacing. Up to 18% of our ICD patients are in need of antibradycardia pacing. Of these pacemaker dependent patients, 80% have an indication for DDD pacing. Our first clinical experience with a DDD-ICD confirms the hemodynamic benefit of AV synchronous pacing in ICD patients with pacemaker syndrome.

Aged↗
PubMed1996

A prophylactic implantable cardioverter-defibrillator?

Antiarrhythmic drugs have systematically failed to improve--or have even worsened prognosis--when given prophylactically to "high-risk" patients without previous spontaneous sustained ventricular arrhythmias. In patients who have had > or = 1 episode(s) of near sudden cardiac death or sustained ventricular arrhythmias, randomized studies against placebo have been considered unethical. Therefore, no information exists on the value of treatment with antiarrhythmic drugs in the prevention of sudden death in these patients. Sudden death is quite predictable and almost expected in some situations. The number of "very high risk" patients is small, but the incidence of sudden death among them is very high. A prophylactic implantable cardioverter-defibrillator (ICD) can be easily justified in them. Unfortunately, the greatest absolute number of sudden deaths occurs in patients from a very large population with a rather low risk for sudden death. Truly unexpected cardiac death is most frequently caused by the first acute ischemic event in a previously asymptomatic individual. While the causes of sudden cardiac death are multiple, the final link is frequently the same: ventricular fibrillation. This arrhythmia can be effectively recognized and treated by an ICD, irrespective of its initiating cause. The time when an ICD will be given prophylactically to a truly asymptomatic individual may never come, but there is an urgent need to implant this device prophylactically in patients who are clearly at risk for sudden death. There are medical, ethical, statistical, technical, practical, financial, and even philosophical obstacles involved in the concept of a prophylactic ICD, but they can be solved, because this therapy is effective. Deciding on the benefits of a prophylactic ICD is a probabilistic issue analogous to deciding on mass vaccination against a preventable infection. To the political community, the decision to accept a prophylactic ICD is too much a matter of expenses, because the benefits may not seem that obvious to them. To the device industry, the cleaves between doctors and politicians have to be the best stimuli to come along with cost-effective technology acceptable to both sides.

Death, Sudden, Cardiac↗
PubMed1995

Surgical treatment of thoracic aneurysm: a 5-year experience.

The surgical results of 77 patients with an aneurysm of the thoracic or thoracoabdominal aorta who were surgically treated during a 5-year period were retrospectively evaluated. Eighty-four operations were performed. The aneurysm was located on the ascending aorta in 20 patients, on the arch in nine, and on the arch and ascending aorta in eight. Sixteen aneurysms involved the descending thoracic aorta and 27 were thoracoabdominal. Associated surgery was performed in 12 patients. Deep hypothermia and circulatory arrest were employed in 30 patients. Partial cardiopulmonary bypass was used in 15 patients. Mortality was significantly higher if operation was performed under emergency conditions: the early mortality rate was 11.7%. Aggressive surgical management of untreated aneurysm is justified, as rupture of such lesions is the most common cause of death and associated mortality is high, with a 5-year survival rate of less than 20%.

Adult↗
PubMed1995

Tricuspid valve replacement: postoperative and long-term results.

A series of 146 consecutive patients who underwent tricuspid valve replacement at the University Brugmann Hospital between 1967 and 1987 was reviewed. Mean age at operation was 51.4 years (+/- 12.1 years). Different types of prostheses were implanted including porcine and bovine pericardial bioprostheses and older and bileaflet mechanical valves. Most patients were severely disabled by their cardiac disease before operation, with 30.1% in New York Heart Association functional class III and 69.9% in class IV. Operative mortality and hospital mortality rates (30 days) were high (16.4%). Incremental risk factors for hospital death included icterus (p < 0.005), preoperative hepatomegaly (p = 0.012), and New York Heart Association functional class IV (p = 0.013). Multivariate analysis only selected preoperative icterus (p < 0.01) as being independently significantly related to hospital mortality. The hospital survivors were followed up for a median of 94 months. A complete follow-up was available for all patients except two for 30 months or more. At 30 months the only two significant parameters were the type of myocardial protection (p = 0.024) and the year of operation (before 1977 or after [precardioplegia era or after], p = 0.011). There were 70 late deaths during the entire follow-up period. The univariate (log-rank statistics) incremental risk factor for late death was the type of tricuspid prosthesis (Smeloff-Cutter and Kay-Shiley versus St. Jude Medical versus bioprosthesis) (p = 0.04). A trend was observed for the type of operative myocardial protection (normothermia and coronary perfusion) (p = 0.06) and preoperative New York Heart Association functional class IV (p = 0.055). Actuarial survival was 74% at 60 months and 23.4% at 180 months. Cumulative follow-up added up to 1015 patient-years. In a more detailed analysis of the effect on survival of the type of tricuspid prosthesis, a significant difference was observed between the bioprostheses and some older mechanical prostheses (Smeloff-Cutter and Kay-Shiley) (p = 0.04) but not between the bioprostheses and the bileaflet valves (p = 0.15). When the follow-up period was stratified according to less than 7 years and more than 7 years of follow-up, no difference was observed for the first period, but for the late follow-up the new mechanical prostheses did better than the bioprostheses (p = 0.05), suggesting a degradation of the bioprostheses after 7 years and favoring mechanical prostheses for those patients with a good long-term prognosis.

Actuarial Analysis↗
PubMed1995

Free-hand sewn allografts, stentless (Prima Edwards) and stented (CESA) porcine bioprostheses. A comparative hemodynamic study.

In a retrospective, non-randomized study, the clinical and hemodynamic properties of 50 consecutively implanted hand-sewn allografts (group I), 50 stentless bioprostheses (group II) and 50 stented bioprostheses (group III) were compared. Preoperative hemodynamic and clinical data were identical in the three groups, except for age (group I: 54.4 +/- 8.7, group II: 67.0 +/- 5.1, group III: 70.0 +/- 5.1). Peak and mean gradients and flow characteristics with echo Doppler were performed at 1 week, 6 and 12 months. For the 21, 23 and 25 diameter prostheses, group differences between groups II and III in peak and mean gradients were not significant after 1 week and 1 year. In all groups, allografts had significantly lower gradients. Regurgitation (I-II) was present after 1 week and 1 year in group I: in 17/48 and 22/42 patients respectively, in group II 7/49 and 11/44 patients and in group III: in 1/49 and 2/44 patients. Early mortality and morbidity were comparable in all groups. Allografts have superior hemodynamic properties. Differences in gradients in groups II and III were not significant, though differences in technique allowed the implantation of a larger bioprostheses in group II. Regurgitation was most prominent in the allograft group. Immediate postoperative results were not influenced by the type of prosthesis.

Adult↗
PubMed1995

The valve choice in tricuspid valve replacement: 25 years of experience.

This study reviews 146 consecutive patients who underwent tricuspid valve replacement (TVR) with 69 bioprostheses (porcine and bovine pericardial) and 77 mechanical ball, disc or bileaflet valves between 1967 and 1987. The mean age was 51.4 +/- 12.1 years. Preoperatively, 97% were in New York Heart Association (NYHA) functional class III or more and over 40% had undergone previous cardiac surgery. Hospital mortality was high (16.1%). Incremental risk factors for hospital death were preoperative icterus (P < 0.01), hepatomegaly (P = 0.02), NYHA functional class IV (P = 0.02) and male sex (P = 0.04) (univariate analysis). Ninety-eight percent of the hospital survivors were followed up for a mean of 92 months. Cumulative follow-up added up to 955 patient-years. There were 70 late deaths. The actuarial survival rate was 74% at 60 months and less than 25% at 14 years. Incremental risk factors for late death indicated by univariate analysis were the type of tricuspid prosthesis (Smel-off-Cutter and Kay-Shiley prostheses) (P = 0.04), the type of operative myocardial protection (normothermia and coronary perfusion) (P = 0.05) and preoperative NYHA functional class IV (P = 0.05). We conclude that TVR carries a high operative risk and poor long-term survival, both influenced by preoperative and perioperative variables. Bearing in mind the poor prognosis for TVR, we prefer a large-sized bioprosthesis, in view of its initial good durability and low risk of valve-related events. However, in patients with good life expectancy, a bileaflet mechanical prosthesis may be an acceptable alternative.

Actuarial Analysis↗
PubMed1995

Prophylaxis in cardiac surgery. A controlled randomized comparison between cefazolin and cefuroxime.

In a prospective randomized two center trial, short-term prophylaxis with cefuroxime (CFX) in 189 patients was compared with cefazolin (CFZ) in 196 patients submitted to elective cardiac surgery. A total of 3 g was administered over 24 h in both groups. One major adverse reaction with CFX was noted. Patients were prospectively screened by infectious disease nurses for surgical wound and secondary infections. Sternal wound infections occurred in eight patients treated with CFX and all were minor. One patient from this group eventually died of infectious causes. In the CFZ-treated patients two major and six minor wound infections occurred requiring extensive debridement in two. Secondary infections occurred less frequently in the CFX group (13.2 per 100) than in the CFZ group (16.8 per 100) with two infection-related deaths in the CFX and one in the CFZ group. The most commonly identified organisms were Staphylococcus aureus and a variety of gram-negative organisms. No major differences were observed between the CFX and CFZ groups. Short-term administration of 3 g CFZ or CFX in this study could not demonstrate the advantage of one of the antibiotics used over the other in terms of clinical outcome, incidence or site of infection or organisms identified. The 24 h administration of 3 g CFZ or CFX provided suboptimal prophylaxis for wound infection or secondary infections in patients undergoing elective open heart surgery.

Adult↗
PubMed1995

At what time are implantable defibrillator shocks delivered? Evidence for individual circadian variance in sudden cardiac death.

BACKGROUND: As in myocardial infarction and transient ischaemia, out-of-hospital sudden cardiac death has an increased morning incidence. However, sudden death occurring in hospital is evenly distributed over the 24 h period suggesting that there might be subgroups of patients with atypical circadian patterns of sudden death. Patients who received an implantable defibrillator constitute an ideal group for studies of circadian patterns of sudden death since this generation of devices are able to store the exact time when defibrillation occurred. METHODS: The distribution of sudden death aborted by the implantable defibrillator was analysed during the 24 h period for 87 presumed appropriate shocks delivered in a group of 22 patients, 18 men and four women, 58.7 +/- 11.9 years old and with a mean left ventricular ejection fraction of 39.4 +/- 17.6%. RESULTS: Each patient received an average of 4.42 +/- 3.04 shocks during a mean follow-up of 9.4 +/- 5.6 months. Apart from a clear tendency for shocks to occur during the morning hours (42% of total shocks), five of 16 patients who received multiple shocks also showed a trend to repeat the shocks around the same period during the day. CONCLUSION: Our results support the accepted view that changes in autonomic tone in the early morning play a role in the circadian variations of sudden death. Sudden death not only occurs more frequently in the morning hours, but it also clusters in certain periods for individual patients.

Adult↗
PubMed1994

Monocytic origin of fibrosis. In vitro transformation of HLA-DR monocytes into neo-fibroblasts: inhibitory effect of all-trans retinoic acid on this process.

We report here the spontaneous in vitro transformation of blood monocytes into fibroblasts in a patient who developed pulmonary fibrosis following ciclosporin-mediated immunosuppression, necessitated by heart transplantation. The blood monocytes with this capacity expressed HLA-DR specificity. Monocytes/macrophages were identified by immunofluorescence using monoclonal antibodies against a specific monocyte/macrophage antigen, while the neo-fibroblasts were identified by electron microscopy and immunofluorescence using monoclonal antibodies against a cytoplasmic enzyme specifically involved in the synthesis of collagen. The secretion of collagen was demonstrated using antibodies against collagen. Both the monocytes/macrophages and the neo-fibroblasts express macrophage and fibroblast markers and are able to synthesize collagen. The all-trans retinoic acid derivative (all-trans RA) inhibits this in vitro transformation of HLA-DR monocytes/macrophages into neo-fibroblasts. Therefore, the possible therapeutic role of all-trans RA in controlling the development of fibrosis remains open to investigation. Until now, no efficient therapy is known for fibrotic diseases which are often lethal when affecting the lungs.

Aged↗
PubMed1994

The implantable cardioverter defibrillator: the end of the thoracotomy approach.

Internal cardioverter defibrillator (ICD) implantation has become a standard therapy for life-threatening arrhythmias. A simple and safe surgical implantation technique is therefore mandatory in this high risk population. In a 30-month period 86 patients received 87 ICD devices. An endocavitary lead system was used as first choice in 62 patients and defibrillation thresholds (DFT) of 25 joules (J) or less were obtained in 57 patients. A thoracotomy approach was avoided using a biphasic shock wave form in 17 patients and the addition of a subcutaneous (sc) patch in 11 patients or wire array lead in 9 patients. There was one early non-technique related death (1.7%) after the transvenous approach. Reoperation was necessary in three patients with lead complications and in two patients for local device problems (one migration, one infection). With the recent progress in ICD technology, a thoracotomy approach could be avoided for the last 52 patients. For comfort and cosmetic reasons left subcostal insertion of the device has been successfully used in the last 50 patients. We conclude that the nonthoracotomy approach can now be offered to all patients in need for an ICD as a consequence of the technological progress made in the field of electric treatment of malignant ventricular arrhythmias. A stepwise approach with a minimum of implanted hardware and the use of biphasic shock systems now offers a simple and efficient treatment alternative with very low perioperative risk. Internal cardioverter defibrillator implantation in combination with open heart procedures can easily be avoided.

Adolescent↗
PubMed1994

Partial mitral valve replacement with a mitral homograft in subacute endocarditis.

In a case of subacute endocarditis, the diseased parts of the mitral valve were replaced by the corresponding parts of a mitral valve homograft. This technique was studied experimentally in animals in the sixties and seventies, but was never performed clinically on a large scale in humans. By preserving a functional papillary muscle and chordae tendinae complex, ventricular function is more efficient than in the case of replacement of the valve by a prosthesis. The absence of any prosthetic material in an infected area also decreases the possibility of reinfection. In performing this type of operation, surgical pit falls such as fistulas at the region of the annulus, dehiscence of papillary muscle, or rupture of the chordae tendinae have to be avoided. Surgeons have to be supplied with high-quality homograft valves of different sizes to obtain optimal hemodynamic results.

Adult↗
PubMed1994

Sternitis and mediastinitis after coronary artery bypass grafting. Analysis of risk factors.

As part of a quality control program, we analyzed possible risk factors in the development of sternitis and mediastinitis after coronary artery bypass grafting. From 1 January 1990 through 31 December 1991, 1,368 consecutive coronary artery bypass grafting procedures were performed at our institution, either alone or in combination with other procedures. Twenty-three patients (1.7%) developed sternitis and/or mediastinitis; 7 (30.4%) of these patients died in an early postoperative phase. Univariate analysis revealed the following statistically significant (p < or = 0.05) risk factors: perfusion time, length of stay in operating room of longer than 5 hours 30 minutes, presence at the operation of a certain surgical resident, revision for bleeding, and postoperative mechanical ventilation lasting longer than 72 hours. After multivariate analysis, statistically significant independent risk factors were: diabetes mellitus, recent cigarette-smoking, reoperation, presence of a certain surgical resident at the operation, revision for bleeding, and length of mechanical ventilation of longer than 72 hours. The use of both internal thoracic arteries was not, in this study, shown to be an independent risk factor. We conclude that although the technique of using both internal thoracic arteries for myocardial revascularization carries no extra risk by itself in the development of sternitis or mediastinitis, associated factors such as prolonged stay in the operating room and reoperation could be responsible for a higher frequency of sternitis-mediastinitis in patients who have undergone this procedure. Therefore, it is advisable to use this technique selectively in high-risk patients. Close surveillance and reporting of wound infections is mandatory to detect risk factor related to the surgical staff (such as Staphylococcus aureus dissemination).

Aged↗
PubMed1992

Deficient acceleration of left ventricular relaxation during exercise after heart transplantation.

BACKGROUND: The exercise-induced rise in left ventricular filling pressures after cardiac transplantation is considered to be the result of a blunted heart rate response, of elevated venous return, and of unfavorable passive late-diastolic properties of the cardiac allograft. In contrast to passive late-diastolic left ventricular properties, the effect of left ventricular relaxation on the exercise-induced rise in left ventricular filling pressures of the cardiac allograft has not yet been studied. In the present study, the response of left ventricular relaxation to exercise was investigated in transplant recipients and compared with left ventricular relaxation observed in normal control subjects exercised to the same heart rate. Moreover, the response of left ventricular relaxation of the cardiac allograft to beta-adrenoreceptor stimulation, to reduced left ventricular afterload, and to increased myocardial activator calcium was investigated by infusion of dobutamine and of nitroprusside and by postextrasystolic potentiation. METHODS AND RESULTS: Twenty-seven transplant recipients were studied 1 year (n = 17), 2 years (n = 7), 3 years (n = 2), and 4 years (n = 1) after transplantation. All patients were free of rejection and of significant graft atherosclerosis at the time of study. Tip-micromanometer left ventricular pressure recordings and cardiac hemodynamics were obtained at rest, during supine bicycle exercise stress testing (n = 27), during dobutamine infusion at a heart rate matching the heart rate at peak exercise (n = 8), during nitroprusside infusion (n = 9), and after postextrasystolic potentiation (n = 10). Tip-micromanometer left ventricular pressure recordings were also obtained in a normal control group (n = 9) at rest and during supine bicycle exercise stress testing to a heart rate, which matched the heart rate of the transplant recipient group at peak exercise. Left ventricular relaxation rate was measured by calculation of a time constant of left ventricular pressure decay (T) derived from an exponential curve fit to the digitized tip-micromanometer left ventricular pressure signal. In the transplant recipients, exercise abbreviated T from 43 +/- 6 to 40 +/- 8 msec (p less than 0.01) and caused a rise of left ventricular minimum diastolic pressure (LVMDP) from 5 +/- 2 to 9 +/- 6 mm Hg (p less than 0.001). In normal control subjects, exercise induced a 2.5 times larger abbreviation of T (from 42 +/- 7 to 34 +/- 6 msec; p less than 0.001) and a small drop in LVMDP from 5 +/- 2 to 4 +/- 3 mm Hg (p less than 0.05). In the transplant recipients, the change in T (delta T) from rest to exercise was variable ranging from an abbreviation, as observed in normal controls, to a prolongation and was significantly correlated with the change in RR interval (delta RR) and the change in left ventricular end-diastolic pressure (delta LVEDP) (delta T = 0.068 delta RR + 0.58 delta LVEDP-2.2; r = 0.76; p less than 0.001). In a first subset of transplant recipients (n = 8), dobutamine infusion resulted in a heart rate equal to the heart rate at peak exercise, a left ventricular end-diastolic pressure (8 +/- 7 mm Hg) lower than at peak exercise (22 +/- 6 mm Hg; p less than 0.05) and a T value (32 +/- 9 msec), which was shorter than both resting value (44 +/- 5 msec; p less than 0.005) and value observed at peak exercise (40 +/- 8 msec; p less than 0.01). In a second subset of transplant recipients (n = 9), nitroprusside infusion and postextrasystolic potentiation resulted in a significant prolongation of T from 41 +/- 7 to 56 +/- 10 msec (p less than 0.05) and a characteristic negative dP/dt upstroke pattern with downward convexity as previously observed in left ventricular hypertrophy. CONCLUSIONS: Exercise after cardiac transplantation resulted in a smaller acceleration of left ventricular relaxation than in a normal control group exercised to the same heart rate...

Adult↗