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Biomedical subjects

B Meyns

Publications and source records attributed to B Meyns.

At least 37 records · Page 2Linked to original sources
PubMed2000

Neonatal pulmonary artery banding does not compromise the short-term function of a Damus-Kaye-Stansel connection.

BACKGROUND: The surgical approach of neonates with a functionally univentricular heart, transposition of the great arteries and excessive pulmonary bloodflow remains a challenge. Pulmonary artery banding remains a valuable option, but may induce ventricular hypertrophy, restriction of the bulboventricular foramen and dysplastic changes of the pulmonary valve. These secondary changes might compromise a later Damus-Kaye-Stansel connection because of pulmonary regurgitation but also a subsequent Fontan repair because of ventricular hypertrophy. The aim of this study is to investigate whether a previous pulmonary artery banding might compromise the function of a Damus-Kaye-Stansel connection. METHODS: Thirteen neonates underwent pulmonary artery banding for functionally univentricular heart, transposition of the great arteries and pulmonary hypertension. Coarctation repair was associated in seven patients. All but one survived the operation. The twelve survivors underwent at a second stage a Damus-Kaye-Stansel connection after a mean interval of 1.1 years. The length of this interval was dictated by the degree of ventricular hypertrophy, the restriction of the bulboventricular foramen and by the degree of cyanosis. The Damus-Kaye-Stansel connection was constructed without any foreign material and with resorbable sutures. Associated procedures were: Glenn/hemi-Fontan (8 pts), Blalock-shunt (2 pts), biventricular correction with a homograft (1 pt), Fontan repair (1 pt). Four patients underwent successfully a Fontan repair at a third stage; seven patients are waiting for such repair. RESULTS: All patients survived the second and third stage of this surgical approach. The mean follow-up after the Damus-Kaye-Stansel connection was 2.5 years. Echocardiography at the last follow-up revealed: PR grade 0 (1 pt), grade 1 (8 pts), and grade 2 (3 pts). All patients - except one patient with a systolic gradient of 24 mmHg - had laminar flow without any gradient in the ascending aorta. All patients, including those who underwent a definitive repair, are doing extremely well. CONCLUSION: This experience demonstrates that a neonatal pulmonary artery banding does not compromise the function neither of a Damus-Kaye-Stansel connection nor a Fontan repair.

Abnormalities, Multiple↗
PubMed2000

Effect of transmyocardial laser revascularization on chronic ischemic hearts in sheep.

BACKGROUND: We investigated the effect of transmyocardial laser revascularization (TMR) on myocardial function and regional blood flow in an animal model of ischemic heart disease. METHODS: Chronic ischemia was induced in 11 sheep by the application of coronary stenosis on the left anterior descending (LAD) and circumflex coronary artery (LCX). Ten weeks later, in six of them, transmyocardial channels were created in the anterior free wall and in the posterior wall of the left ventricle. Five animals served as controls. The myocardial function was assessed by echocardiography taken at baseline and every 2 weeks after coronary stenosis and after TMR. Myocardial perfusion was measured by colored microspheres, injected at baseline, immediately after coronary stenosis, before and after TMR, and at 20 weeks after coronary stenosis. The hearts were retrieved at 20 weeks for light microscopic examination. RESULTS: The left ventricular end-diastolic and end-systolic cavity area was elevated 20 weeks after coronary stenosis in the control and TMR groups. There was no difference between groups (analysis of variance; ANOVA, non-significant). The wall thickening fraction (WTF) decreased progressively and significantly after coronary stenosis in both groups. The WTF was further acutely reduced by TMR, and recovered gradually to the pre-TMR level. No significant difference in WTF was observed between the TMR and control groups. The resting myocardial blood flow was significantly increased by TMR at 20 weeks (P=0.03). Light microscopic examination revealed channel patency in 49% of the laser scars at 10 weeks post-TMR. A dense capillary network was observed at the edges of the surrounding scar. CONCLUSIONS: In an experimental model of ischemic heart disease, TMR developed angiogenesis in the lased channels, but, however, failed to improve myocardial function.

Animals↗
PubMed2000

The effect of sudden failure of a rotary blood pump on left ventricular performance in normal and failing hearts.

We investigated the hemodynamic effect of regurgitation (or back-flow) due to sudden failure of a rotary blood pump (diagonal pump). Seven healthy sheep (Group C) and 7 with chronic heart failure (Group F) were studied. Chronic heart failure was obtained by intracoronary injection of microspheres several weeks earlier. Left ventricular function and ventricular efficacy were assessed by the pressure-volume relationship. The back-flow through the stopped pump was significantly lower in Group F (2.3 +/- 0.34 L/min) than in Group C (2.8 +/- 0.33 L/min). Mean aortic blood pressure dropped significantly from 68.3 +/- 9.65 to 61.9 +/- 9.75 mm Hg in Group C and from 62.5 +/- 9.12 to 51.5 +/- 9.08 in Group F but remained stable during the 15 min period of pump stop. Parameters of left ventricular contractility (preload recruitable stroke work) dropped significantly in both groups, remained stable during the pump stop, and returned to baseline values 30 min after the end of back-flow. The ventricular efficacy (in terms of energy transfer) was tolerant against this acute volume overload even in the failing hearts. Sudden pump failure of a rotary blood pump leads to an acute depression of the hemodynamic state and myocardial contractility. However, this depression remained stable over 15 min, did not lead to further deterioration of the animals, and was completely reversible.

Analysis of Variance↗
PubMed2000

Mechanical support with microaxial blood pumps for postcardiotomy left ventricular failure: can outcome be predicted?

OBJECTIVE: We sought to identify the indications of mechanical support in postcardiotomy left ventricular failure in patients who are unable to undergo transplantation. METHODS: From 1989 through 1997, 61 patients with postcardiotomy left ventricular failure beyond intra-aortic balloon pumping were assisted with the Hemopump cardiac assist system (Medtronic, Minneapolis, Minn). Their mean age was 64 +/- 8 years. Comorbidity was prevalent; 47% underwent cardiac massage before pump support, and evolving myocardial infarction was diagnosed in 43% before surgery. Multivariable logistic regression of data known at the moment of pump insertion was performed to identify the risk factors for mortality. RESULTS: Sixty-five percent of the patients were weaned from the device, but only 30% were discharged home. Cardiac index evolution during the first hours after pump insertion (P <.001) is the only independent predictor for possibility to wean from the device in the multivariable analysis. Acute renal failure is the only variable retained in the model for 90-day mortality. Device-related complications were far more frequent with the femoral (54%) than with the transthoracic (6%) cannula. Only 13% of the patients had bleeding complications. CONCLUSIONS: One third of the patients with postcardiotomy heart failure refractory to use of the intra-aortic balloon pump can be saved with the use of an endovascular axial flow pump. It is impossible to predict lethal outcome on preoperative data alone. The early hemodynamic response to support seems to be related to functional recovery of the heart and subsequent weaning from the device.

Cardiac Surgical Procedures↗
PubMed2000

Femoral venoarterial extracorporeal membrane oxygenation for severe reimplantation response after lung transplantation.

Severe pulmonary reimplantation response after lung transplantation is not very common, although the mortality can be high. We present a patient who developed an extremely severe reperfusion injury after bilateral lung transplantation. Because of severe hypoxia and hemodynamic instability, despite aggressive ventilator settings, venoarterial extracorporeal membrane oxygenation (ECMO) was instituted using the femoral approach at the bedside. During ECMO, the patient developed a thoracic wall hematoma that was treated with transfusion alone. After 50 h of ECMO, his chest radiograph had dramatically improved, his oxygen need had been reduced to 50%, and he was successfully weaned from ECMO. Two years later, he is doing extremely well. Therefore, institution of ECMO using the femoral approach can be performed safely at the bedside in the ICU, and can be lifesaving in the context of a very severe reimplantation response after lung transplantation.

Catheters, Indwelling↗
PubMed1999

The intra-aortic cannula pump: A novel assist device for the acutely failing heart.

OBJECTIVE: The intra-aortic cannula pump is a catheter pump designed to support the acutely failing heart. It expels blood from the left ventricle into the ascending aorta in a pulsatile flow pattern. The aim of the study was to analyze the hemodynamic performance of this new intracardiac support system in acute heart failure. METHODS: A 24F cannula was studied in a series of 16 sheep. Hemodynamic changes were assessed in the nonfailing, the moderately failing, and the severely failing heart. Heart failure was induced by an injection of microspheres into the left anterior descending coronary artery. The cannula was inserted through the aortic arch and introduced through the aortic valve into the left ventricle. RESULTS: Cannula insertion was feasible in all animals. Flow through the intra-aortic cannula flow was increased to a maximum of 3 L/min. No hemodynamic changes were observed in the nonfailing heart. A significant increase in cardiac output was observed in the moderately and severely reduced left ventricle (2.67 +/- 0.7 L to 3.51 +/- 0.83 L; P =.001; and 1.18 +/- 0.77 L to 2.43 +/- 0.44 L; P =.001, respectively). A drop in left atrial pressure was achieved in moderate and severe heart failure (14.1 +/- 5.93 mm Hg to 9.71 +/- 2.63 mm Hg; P =.0001; and 23 +/- 7.16 mm Hg to 11.2 +/- 2.55 mm Hg; P = 0.0001, respectively). Systolic and diastolic systemic blood pressures increased in the severely failing heart (57.3 +/- 12.8 mm Hg to 75.4 +/- 11.2 mm Hg; P =.0001; and 35.6 +/- 8.2 mm Hg to 60 +/- 14.3 mm Hg; P =.0006, respectively). CONCLUSIONS: Hemodynamic data demonstrate the beneficial effects of the intra-aortic cannula pump in moderate and severe heart failure. The intra-aortic cannula pump represents a new modality for the treatment of acute heart failure.

Animals↗
PubMed1999

Aortic stenosis in endogenous ochronosis.

Endogenous ochronosis, a rare inherited disease of tyrosine metabolism, is caused by a deficiency of the enzyme, homogentisic acid oxidase, and may lead to cardiovascular involvement seen most frequently as aortic valve stenosis. We report the case of a patient with generalized ochronosis who developed cardiovascular symptoms due to aortic valve stenosis and who underwent aortic valve replacement.

Aged↗
PubMed1999

The enabler cannula pump: a novel circulatory support system.

BACKGROUND: The enabler circulatory support system is a catheter pump which expels blood from the left or right ventricular cavity and provides pulsatile flow in the ascending aorta or pulmonary artery. It is driven by a bedside installed pulsatile driving console. The device can easily be implanted by a minimal invasive approach, similar to the Hemopump. PURPOSE: To demonstrate the hemodynamic performance of this new intracardiac support system. METHODS: In a series of 9 sheep, hemodynamic evolutions were recorded in various conditions of myocardial contractility (the non-failing, the moderately failing and the severely failing heart). Heart failure was induced by injection of microspheres in the coronary arteries. RESULTS: Introduction of the cannula through the aortic valve was feasible in all cases. Pump flow by the enabler was gradually increased to a maximum of 3.5 L/min. Diastolic (and mean) aortic blood pressure is significantly increased in the non-failing and moderately failing condition (counterpulsation mode). In heart failure, cardiac output is significantly increased by the pump (p < 0.0001). A drop in left atrial pressure (indicating unloading) is achieved in all conditions but reaches significant levels only during heart failure (p=0.0068). CONCLUSIONS: This new circulatory support system contributes to stabilization of the circulation in the presence of cardiac unloading. In heart failure it actually supports the circulation by increasing cardiac output and perfusion pressure.

Animals↗
PubMed1999

Chronic heart failure model induced by coronary embolization in sheep.

OBJECTIVE: To create a model of chronic heart failure in a large animal. METHODS: Heart failure was induced in sheep by single intracoronary injection of polymer macrobeads, which were administered into left main coronary artery (n=3) or selectively into left anterior descending (n=4) or left circumflex (n=5) coronary artery. The animals were followed by echocardigraphy for 20 weeks. Measurements comprised fractional area change (FAC), and diastolic ventricular area (EDVA) and regional wall-thickening fraction (WT%). RESULTS: EDVA increased from 14.2+/-2.1 cm2 prior to embolization to 16.9+/-3.1 cm2 on day 1 (p<0.05), and remained significantly increased until completion of the follow-up period. FAC dropped from 47.9+/-4.6% at baseline to 29.3+/-4.4% on day 1 (p<0.001) and remained significantly depressed until 20 weeks later. In 9 selectively embolized animals WT% of the embolized area decreased from 33.8+/-8.0% at baseline to 5.3+/-2.6% on day 1 and remained significantly decreased. CONCLUSIONS: A simple model of chronic heart failure was developed. It shows relatively high stability over time and may prove beneficial in experimental work on ventricular assist devices.

Animals↗
PubMed1998

Is return of angina after coronary artery bypass grafting immutable, can it be delayed, and is it important?

BACKGROUND: Because survival after either an operation or angioplasty is similar across a wide spectrum of coronary patients, lasting symptom relief assumes high priority. OBJECTIVES: The objectives of this observational clinical study were (1) to determine whether the return of angina is immutable; (2) to identify factors that might delay its return, and (3) to evaluate whether its return is predictive of subsequent adverse events. METHODS: The return of angina of any degree of severity and morbid events subsequent to its return were studied by multivariable time-related analyses in a consecutive series of 9600 patients who were undergoing primary isolated coronary bypass operations between 1971 and 1992. RESULTS: The freedom rate from return of angina was 94%, 82%, 61% and 38% at 1, 5, 10, and 15 years. Increased modest risk of early return of angina was associated with preoperative demographic, symptom, coronary and vascular disease variables but reduced by more extensive arterial grafting. The ever-increasing risk of late return of angina was associated with demographic, symptomatic, left ventricular function, and coronary disease variables and was related strongly to comorbidity but was weakly reduced by controllable surgical variables. After the return of angina, 10-year freedom rate from infarct and survival was 71% and 68% respectively. CONCLUSIONS: (1) The risk of angina return increases relentlessly after operation, so it is likely immutable. (2) Delay of late angina return by use of arterial grafting is clinically trivial; control of noncardiac comorbidity may be more effective. (3) Fortunately, the return of angina after coronary artery bypass grafting has minimal impact on survival and is not predictive of imminent infarct.

Angina Pectoris↗
PubMed1998

Miniaturized implantable rotary blood pump in atrial-aortic position supports and unloads the failing heart.

The purpose of this study was to test the pump performance of a miniaturized, newly developed, implantable rotary blood pump (the diagonal pump). In a series of six sheep, the pump was interposed in an atrial-aortic connection. Heart failure was induced by serial injection of glass beads into the left coronary artery. The assistance of the non-failing heart (with pump output up to 4.5 liter/min) did not change the total cardiac output or the blood pressure of the animal. The heart was significantly unloaded as demonstrated by a drop in first derivative of the left ventricular pressure (dP/dt) max (from 1645 to 1113 mmHg/s; P = 0.0003). Because of the specific interaction between heart function and rotary blood pump performance, the pump provided considerably more flow in the failing than in the non-failing heart. Cardiac output and perfusion pressures were restored to pre-assist values in the failing heart model. The heart-rotary blood pump interaction is an ideal substrate for long-term assistance. With this miniaturized rotary blood pump, hemodynamics in a severely failing heart can be restored. Atrial cannulation, which leaves the left ventricle untouched, provides similar results as apical cannulation in the failing heart.

Animals↗
PubMed1998

First cardiological or cardiosurgical reintervention for ischemic heart disease after primary coronary artery bypass grafting.

OBJECTIVE: To study the first reintervention for ischemic heart disease anytime after coronary artery bypass grafting (CABG) and the variables that drive its need or bias its occurrence. Reintervention is defined as an isolated or combined repeat surgical or cardiological procedure for ischemic heart disease. METHODS: A consecutive series of 9600 CABG patients (1971-1992) were followed for up to 20 years (99.9% complete). A multivariable time-related analysis was performed. RESULTS: The 1-, 10- and 15-year freedom from reintervention was 99, 89 and 72% respectively. A three-phase hazard function was identified. Patient variables influencing early freedom included anginal instability, completeness of revascularization and institutional variables. Late freedom was influenced importantly by demographic variables, cardiac and non-cardiac comorbidity and extensive arterial grafting. The 1-month and 10-year survival after reintervention was 95 and 73%. The 1- and 10-year freedom from angina after reintervention was 74 and 32%. CONCLUSION: Reinterventions for ischemic heart disease by interventional cardiology or surgery are rather infrequent in the first decade after CABG but nearly half the patients surviving their second decade undergo one. The increased reintervention rate, apparent after 1985 did not go parallel with improved late post-CABG survival. Older age and the presence of multiple arterial grafts seem to reduce but also to bias the event. The very good survival, only when return of angina is present, suggests a more restrictive differential therapy approach, certainly in the presence of a well functioning arterial graft to the antero-septal region and where the co-morbidity might induce a high reinterventional survival cost.

Angioplasty, Balloon, Coronary↗
PubMed1998

Lipoprotein(a) changes during and after coronary artery bypass grafting: an epiphenomenon?

The lipoprotein(a) (Lp(a)) time course during and after coronary artery bypass grafting was examined in 20 caucasoid patients, in relation to the time courses of serum cholesterol and serum triglycerides. Samples were taken at eight different time points. Baseline geometric means (SD) for Lp(a), cholesterol and triglycerides were 115 (336) mg/L, 5.73 (1.10) mmol/L and 1.73 (1.21) mmol/L, respectively. Up to 10 min after cardiopulmonary bypass (CPB) and after correction for haemodilution, no observable effect of CPB on serum concentrations of Lp(a) could be demonstrated, whereas serum concentrations of total cholesterol and triglycerides showed a progressive and significant decline. Ten minutes after stopping CPB geometric means for cholesterol and triglyceride were 3.90 (0.82) and 0.90 (0.58) mmol/L, respectively. At the third post-operative day geometric Lp(a) and cholesterol means decreased to 62(90) mg/L and 2.97 (0.84) mmol/L, respectively, while triglycerides went up. It is concluded that Lp(a) levels remain constant during CPB, but mimic total cholesterol changes in the post-CABG period.

Adult↗
PubMed1997

Follow-up of aortic dissection: contribution of MR angiography for evaluation of the abdominal aorta and its branches.

Spin-echo MR is an established method to evaluate thoracic aortic dissections, but is not well suited to study the abdominal aorta. In this study we evaluated whether MR angiography could provide a complete examination of the abdominal aorta. In 28 patients (40 MR studies) with suspected (n = 6) or known (n = 34) aortic dissection, MR studies were performed. Thoracic aorta was evaluated with spin-echo and gradient-recalled-echo MR imaging. Axial two-dimensional time-of-flight MR angiography with thin overlapping slices was used to study the abdominal aorta. Intermediate and high signal intensity on MR angiography was interpreted as patent flow, and low signal was interpreted as thrombus. The presence of an intima flap and the re-entry site could be depicted in all MR studies. Thrombus in the false channel was seen in 8 studies. The origin of the abdominal visceral branches and their relation to the false-true channel could be depicted, except in 4 of 80 renal arteries studied. Extension of the dissection into the coeliac trunk was seen in 2 and in the superior mesenteric artery in 10 studies. Dilatation of the suprarenal abdominal aorta was seen in 20 studies, and of the infrarenal aorta in 9 studies. MR angiography provides valuable information about the abdominal aorta and its branches in patients with aortic dissection. This makes MR imaging appealing as the preferred imaging modality for the diagnosis and follow-up of aortic dissection.

Aortic Dissection↗
PubMed1997

Organ perfusion with Hemopump device assistance with and without intraaortic balloon pumping.

OBJECTIVE: Our objective was to analyze the potential advantage of combining an intraaortic balloon pump with a transthoracic Hemopump device (Medtronic, Inc., Minneapolis, Minn.) (Nimbus Medical, Inc., Rancho Cordova, Calif.). METHODS: Twelve sheep underwent implantation of a transthoracic Hemopump device and an intraaortic balloon pump. In the first series (n = 6), we analyzed the influence of the counterpulsation on the performance of the Hemopump device. In the second group (n = 6), hemodynamic changes, myocardial wall thickening, organ perfusion, and myocardial perfusion (determined with colored microspheres) were analyzed under the following conditions: (1) control situation, (2) during application of coronary stenosis, (3) during support with the Hemopump device, and (4) during support with the Hemopump device combined with intraaortic balloon pump support. RESULTS: In the first series, we found that addition of counterpulsation reduced output with the Hemopump device by 11.1% +/- 6%. In the second series, it was shown that coronary stenosis significantly reduced contractility (rate of pressure change and wall thickening) but did not cause hemodynamic collapse. Myocardial blood flow was significantly reduced in the poststenotic subendocardial regions (mean subendocardial blood flow dropped from 78 +/- 33 to 24 +/- 17 ml/min/100 gm; p = 0.0486). Support with the Hemopump device alone improved the ratio of subendocardial to subepicardial blood flow, but endocardial underperfusion remained (analysis of variance, p < 0.001). The Hemopump device with an intraaortic balloon pump completely restored perfusion in poststenotic regions. Peripheral organ perfusion did not change during ischemia or mechanical support. CONCLUSIONS: The association of balloon counterpulsation with the Hemopump device reduces the Hemopump output by 11% and increases myocardial blood flow to ischemic regions. Perfusion to peripheral organs remains unaltered. The transthoracic Hemopump device combined with an intraaortic balloon pump is an ideal support system for the ischemic, failing heart.

Analysis of Variance↗