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Biomedical subjects

M L Jacobs

Publications and source records attributed to M L Jacobs.

At least 55 records · Page 3Linked to original sources
PubMed1995

[Improved diabetes control through strict observance of the standard 'Type II Diabetes Mellitus' from the Dutch College of Family Physicians].

OBJECTIVE: Comparison of diabetes regulation by strict or less strict observance of the relevant standard protocol of the Netherlands College of General Practitioners (NHG standard). SETTING: Two general practices in the region 'Nieuwe Waterweg Noord', near Rotterdam, the Netherlands. DESIGN: Cross-sectional comparative descriptive study. METHOD: Type II diabetic patients from two general practices were investigated for diabetic symptoms, type of medication, metabolic abnormalities and (risk factors for) complications in relation to their HbA1c as a measure of mean blood glucose regulation. One GP strictly observed the NHG standard as a protocol, the other GP used it as a guideline. RESULTS: Metabolic control was significantly better in the 'strictly observing' general practice than in the 'guideline' practice: HbA1c 7.3% (SD: 1.7) versus 8.1% (1.5) (p < 0.01). Systolic blood pressure was also significantly lower in the 'strict' practice: 141 mmHg (23) versus 155 mmHg (21) (p < 0.01), but mean age was lower and mean duration of diabetes was significantly shorter. The prevalence of macrovascular complications, diabetic retinopathy and nephropathy did not differ significantly in these practices; symptoms of polyneuropathy, however, were found more often in the patients of the 'strict' practice (41% versus 20%; p < 0.05). CONCLUSION: Good metabolic control in patients with type II diabetes mellitus is made possible by strict application of the NHG standard for general practitioners.

Adult↗
PubMed1995

Avoidance of subaortic obstruction in staged management of single ventricle.

BACKGROUND: Subaortic obstruction is a frequent accompaniment of single-ventricle anatomy. Most often, the aorta arises from an outflow chamber that is connected to the single ventricle by a bulboventricular foramen or ventricular septal defect. This connection may be restrictive of flow at birth, or may become obstructive after surgical procedures that reduce the volume work of the ventricle. Subaortic obstruction is recognized as a risk factor for reconstructive surgical procedures for single ventricle. METHODS: To prevent the consequences of subaortic obstruction, we have routinely amalgamated the proximal main pulmonary artery with the ascending aorta and arch early in the management of these patients. From September 1990 through September 1994, 29 neonates and infants with single ventricle and established or potential subaortic obstruction underwent staged reconstructive surgical procedures. The initial operation in the newborn period was a Norwood procedure (18 patients) or a pulmonary artery band (5 patients). All survivors underwent a hemi-Fontan procedure at approximately 6 months. RESULTS: Eighteen patients have undergone a completion Fontan operation with no deaths. Five await completion Fontan. None has subaortic obstruction, and none has pulmonary valve insufficiency that is graded more than mild. CONCLUSIONS: Early association of the proximal main pulmonary artery with the ascending aorta appears to obviate the risks and complications associated with subaortic obstruction in patients with single ventricle.

Cardiac Surgical Procedures↗
PubMed1995

Acute changes in left ventricular geometry after volume reduction operation.

BACKGROUND: After surgical removal of a volume load, regression of myocardial mass proceeds slowly relative to diminution in ventricular cavity size, resulting in increased wall thickness and decreased cavity dimensions, which may affect the filling properties and performance of the heart. We investigated the acute changes in ventricular geometry that occur after the Fontan operation and hemi-Fontan operation for tricuspid atresia, and compared them with closure of a ventricular septal defect in a two-ventricle heart. METHODS: We reviewed the results of echocardiography performed before and 8 +/- 7 days after (1) Fontan operation for tricuspid atresia (n = 9), (2) hemi-Fontan operation for tricuspid atresia (n = 10), and (3) closure of a ventricular septal defect (n = 13). Measurements were made from images of the left ventricle at end-diastole: (1) apical, septal, and posterior wall thickness; and (2) long- and short-axis cavity diameters, cross-sectional areas, and ventricular volume. Posterior wall thickness to cavity dimension ratio was calculated. RESULTS: Wall thickness increased in all groups, with the greatest degree of increase after the Fontan operation. Cavity measures decreased most dramatically after the Fontan operation, with less dramatic and equivalent changes noted after the hemi-Fontan operation and ventricular septal defect closure. Posterior wall thickness to cavity diameter ratios were equivalent in all before operation, increased after operation, and were greatest after the Fontan operation. CONCLUSIONS: Changes in ventricular geometry identified as an increase in wall thickness and a decrease in cavity dimension are most dramatic after the Fontan operation. Changes seen after the hemi-Fontan operation are of a milder degree, which may in part explain the excellent clinical course after this operation.

Child, Preschool↗
PubMed1995

Early changes in ventricular septal defect size and ventricular geometry in the single left ventricle after volume-unloading surgery.

OBJECTIVES: This study investigated the phenomenon of, and the relation between, alterations in ventricular geometry after acute surgical volume unloading of the ventricle and the development of subaortic stenosis in patients with a single ventricle and ventricular septal defect-dependent systemic flow. BACKGROUND: Subaortic outflow obstruction has been observed to occur in patients with a single left ventricle after placement of a pulmonary artery band. The timing and etiology of this phenomenon are not well defined. METHODS: The preoperative and postoperative echocardiograms of 18 patients 14.9 +/- 22.8 months old (mean +/- SD) with a diagnosis of single left ventricle who underwent pulmonary artery banding or cavopulmonary connection were reviewed. Postoperative studies were performed a mean of 7.0 +/- 6.5 days after operation. The ventricular septal defect diameter was measured in two orthogonal views and the area calculated using the formula for an ellipse. Interventricular septal and posterior wall thickness and left ventricular diameter and length were also measured. RESULTS: Mean ventricular septal defect area indexed to body surface area diminished by 36 +/- 23% (3.1 +/- 2.7 to 2.0 +/- 1.8 cm2/m2, p < 0.01). Mean interventricular septal and posterior wall thickness increased significantly, and left ventricular diameter and length decreased significantly. A greater diminution in ventricular septal defect area was noted after cavopulmonary connection (41 +/- 19%, p < 0.01) than after pulmonary artery banding (25 +/- 28%, p = 0.22). CONCLUSIONS: In the single left ventricle, diminution in ventricular septal defect size occurs early and is related to an acute alteration in ventricular geometry that accompanies the decrease in ventricular volume. Ventricular septal defect diminution was greater after volume unloading of the ventricle after cavopulmonary connection than after pulmonary artery banding.

Aortic Stenosis, Subvalvular↗
PubMed1995

Results of Norwood's operation for lesions other than hypoplastic left heart syndrome.

Norwood's operation provides satisfactory palliation for neonates with hypoplastic left heart syndrome. The dominant physiologic features of hypoplastic left heart syndrome, ductal dependency of the systemic circulation and parallel pulmonary and systemic circulations, are shared by a multitude of other less common congenital heart malformations. Theoretically, these should be equally amenable to palliation by Norwood's operation. Between January 1990 and June 1994, 60 neonates with malformations other than hypoplastic left heart syndrome underwent initial surgical palliation by Norwood's procedure. Diagnoses included single left ventricle with levo-transposition of the great arteries (12); critical aortic stenosis (8); complex double-outlet right ventricle (8); interrupted aortic arch with ventricular septal defect and subaortic stenosis (7); ventricular septal defect, subaortic stenosis, and coarctation of the aorta (7); aortic atresia with large ventricular septal defect (6); tricuspid atresia with transposition of the great arteries (6); heterotaxy syndrome with subaortic obstruction (3); and other (3). There were 10 hospital deaths and 50 survivors (83% survival). After the introduction of inspired carbon dioxide therapy into the postoperative management protocol (1991), 42 of 47 patients survived (89% survival). Mortality was independent of diagnosis and essentially the same as that for hypoplastic left heart syndrome. With minor technical modifications, Norwood's operation provides satisfactory initial palliation for a wide variety of malformations characterized by ductal dependency of the systemic circulation in anticipation of either a Fontan procedure or a biventricular repair.

Aorta, Thoracic↗
PubMed1994

Fontan operation: influence of modifications on morbidity and mortality.

The mortality rate of the Fontan operation for heart malformations with a single or dominant ventricle has been reduced by dividing the procedure into two stages. The hemi-Fontan procedure allows early reduction of the volume work of the single ventricle and remodeling of ventricular geometry before a completion Fontan operation. Despite the improvement of survival with this strategy (8% mortality for completion Fontan versus 16% mortality for primary Fontan operation), morbidity related to serous effusions remains substantial. Further technical modifications have been undertaken in an effort to reduce morbidity and further reduce mortality. From January 1990 through June 1993, 200 patients underwent completion Fontan procedures after previous hemi-Fontan operations. Mean age was 23 months, and 157 patients were less than 24 months of age. Diagnoses were hypoplastic left heart syndrome (127 patients), tricuspid atresia (19 patients), single left ventricle (17 patients), complex double-outlet right ventricle (16 patients), pulmonary atresia with intact ventricular septum (8 patients), and other (13 patients). Overall, early mortality rate was 8% (16 patients). In the last 112 patients, the procedure was modified technically by creating one or more fenestrations in the baffle used to separate systemic venous blood from pulmonary venous blood (36 patients), or by excluding one or more hepatic veins from the systemic venous pathway (76 patients). Early mortality for these 112 patients was reduced to 4.5% (5 patients). Substantial morbidity from serous effusions occurred at a rate of 45% (35 of 78 patients) among survivors who had received neither technical modification.(ABSTRACT TRUNCATED AT 250 WORDS)

Double Outlet Right Ventricle↗
PubMed1994

Glucagon stimulation test: assessment of beta-cell function in gestational diabetes mellitus.

OBJECTIVE: Because women with gestational diabetes mellitus have a risk of up to 60% for the later development of type II diabetes, we used the intravenous glucagon stimulation test to evaluate beta-cell function in pregnant women. PATIENTS: Twenty-seven pregnant women with one or more risk factors for gestational diabetes had an intravenous beta-cell stimulation test. Glucose, C-peptide and insulin levels were measured at baseline and 5, 10 and 15 min after the administration of 1 mg glucagon. The women were classified using the 75-g oral glucose tolerance test according to World Health Organization criteria. During the oral glucose tolerance test glucose, C-peptide and insulin levels were measured at baseline and at 2 h. RESULTS: Insulin and C-peptide responses were significantly lower in pregnant women with impaired glucose tolerance and diabetes compared with women with normal glucose tolerance. CONCLUSION: This study shows gradually decreasing insulin secretion from normal to subnormal in pregnant women without and with glucose intolerance, and diabetes mellitus, respectively.

Adult↗
PubMed1994

Early changes in ventricular geometry and ventricular septal defect size following Rastelli operation or intraventricular baffle repair for conotruncal anomaly. A cause for development of subaortic stenosis.

BACKGROUND: Obstruction to left ventricular outflow can be seen after surgical repair of congenital heart disease in which a ventricular septal defect (VSD) is closed by means of a baffle to the systemic great artery arising from the right ventricle (Rastelli operation, intraventricular repair, for conotruncal anomaly). We investigated the hypothesis that obligatory volumetric changes that occur after this operation lead to acute alterations in ventricular geometry and VSD size, resulting in subsequent subaortic stenosis in patients who were thought before operation to have a large, nonrestrictive VSD orifice. METHODS AND RESULTS: Preoperative and postoperative echocardiograms and medical records of 24 patients with conotruncal anomaly who underwent conventional Rastelli operation or intraventricular repair in which the VSD was used as part of a new left ventricular outflow were reviewed. Eleven patients had transposition of the great arteries with pulmonic stenosis, 7 had double-outlet right ventricle, and 6 had subaortic atresia or stenosis with a normal-size left ventricle and underwent Norwood's palliation in infancy. All had large, nonrestrictive VSDs at preoperative cardiac catheterization. The mean age at the time of surgery was 32 +/- 24 months. The following measurements were made from two-dimensional echocardiographic images obtained before and 5 +/- 4 days after surgery from the subcostal views at end diastole: (1) VSD diameter; (2) short-axis left ventricular internal diameter (LVID); (3) left ventricular posterior wall thickness (LVPW); and (4) systemic great artery diameter (arising from the right ventricle). VSD diameter diminished significantly after surgery (11.6 +/- 3.6 versus 10.1 +/- 3.7 mm, P < .0001), as did LVID (34.9 +/- 5.0 versus 31.7 +/- 5.1 mm, P < .001). LVPW thickness increased significantly (5.7 +/- 1.0 versus 6.7 +/- 1.1 mm, P < .0001), while great artery diameter was unchanged (16.2 +/- 4.0 versus 16.7 +/- 3.8 mm, P = NS). Percent change in VSD dimension correlated with percent change in LVPW/LVIDD ratio (degree of ventricular "contraction"). Nine patients subsequently developed subaortic obstruction at the VSD orifice level and had a greater degree of early diminution in VSD size (21 +/- 8% versus 10 +/- 8%, P < .002) as well as postoperative change in LVPW/LVID ratio (0.24 +/- 0.04 versus 0.20 +/- 0.02, P < .002) than those who did not develop subsequent subaortic obstruction. CONCLUSIONS: The left ventricle undergoes geometric change after Rastelli operation or intraventricular repair, surgeries in which the VSD is used as the new left ventricular outflow. These changes are manifested as increased wall thickness, decreased cavity dimensions, and a decrease in VSD size. Patients who subsequently develop left ventricular outflow obstruction have the greatest degree of ventricular contraction and VSD diminution early after surgery.

Child, Preschool↗
PubMed1994

Experimental model of single ventricle. Influence of carbon dioxide on pulmonary vascular dynamics.

BACKGROUND: Important in the postoperative management of neonates with single-ventricle complexes, such as hypoplastic left heart syndrome and pulmonary atresia with intact ventricular septum, is the fact that the pulmonary circulation is connected to the systemic circulation via a shunt. The distribution of flow to the pulmonary and systemic vascular beds depends directly on the pulmonary-to-systemic vascular resistance ratio. Changes in this ratio result in alterations in flow that have an impact on survival. METHODS AND RESULTS: PICO2 has a potent effect on pulmonary vascular resistance. In this study, the addition of CO2 to inspired gas (PICO2) is assessed as a means of modulating the ratio of pulmonary-to-systemic vascular resistance and thus flow, while avoiding the consequences of hypoventilation. Thirteen neonatal piglets (age, 17 to 30 days) were subjected to atrial septectomy, patch closure of the tricuspid valve, and creation of a 4-mm systemic-to-pulmonary arterial shunt to mimic the physiology of single-ventricle complexes. Pulmonary and systemic flows; aortic, pulmonary artery, and atrial pressures; and arterial blood gases were measured with the addition of different levels of CO2 to the inspired gases (PICO2 = 0 to 35 mmHg). In all animals, pulmonary vascular resistance (PVR) increased in direct correlation with PICO2. In group 1 (n = 8), PVR increased in direct correlation with PICO2 and PACO2, and inversely with respect to pH (r = .98, .74, and .83, respectively). Group 2 animals (n = 5) received infusions of Tham to buffer hydrogen ion and compensate for respiratory acidosis. PVR again increased in direct correlation with FICO2 (r = .97). In both groups, systemic vascular resistance (SVR) was less directly influenced by FICO2 (r = .53). CONCLUSIONS: CO2 exerts a vasoactive influence on pulmonary vasculature that is largely independent of SVR and pH. Regulating PICO2 is an effective means of achieving a favorable ratio of pulmonary-to-systemic vascular resistance and thus flow in the fragile physiology encountered in neonates with single-ventricle complexes.

Animals↗
PubMed1994

The pharmacokinetics of injectable allopurinol in newborns with the hypoplastic left heart syndrome.

OBJECTIVE: The purpose of this investigation was to determine the pharmacokinetic disposition of intravenous allopurinol and its metabolite oxypurinol in neonates with the hypoplastic left heart syndrome (HLHS) and to evaluate the subsequent degree of xanthine oxidase inhibition using serum uric acid as a marker. METHODS: Pharmacokinetic data were evaluated in 12 stable preoperative neonates with HLHS after a single intravenous allopurinol administration of 5 mg/kg or 10 mg/kg. Pharmacokinetic parameters were determined for elimination half-life, clearance, volume of distribution, and mean residence time. Xanthine oxidase inhibition, measured by serum uric acid reduction, was also measured. RESULTS: Pharmacokinetic parameters revealed no statistically significant differences between a 5-mg/kg and 10-mg/kg dose of intravenous allopurinol on elimination half-life, clearance, volume of distribution, and mean residence time. Mean serum uric acid levels were significantly reduced from baseline by 39.99 and 42.94%, respectively, in the 5- and 10-mg/kg treatment groups. DISCUSSION: The enzyme xanthine oxidase plays a key biochemical role in the generation of toxic oxygen-derived free radicals during ischemia-reperfusion conditions. Allopurinol and its active metabolite oxypurinol inhibit xanthine oxidase, and significantly reduce the conversion of hypoxanthine to xanthine and xanthine to uric acid. Cell injury may be caused by toxic oxygen free radicals produced by ischemia-reperfusion injury such as could occur during the repair of HLHS under hypothermic total circulatory arrest. We hypothesize that allopurinol may provide protection from cellular injury in this clinical context.

Allopurinol↗
PubMed1993

Fontan's procedure in two stages.

Since 1985, 381 patients with various cardiac malformations that share the central common feature of only one effective ventricle have been treated with some modification of Fontan's operation. Since 1989, the Fontan operation has been staged by associating the superior vena cava with the branch pulmonary arteries (hemi-Fontan) initially followed, some months later, by associating the inferior vena cava to the branch pulmonary arteries (completion Fontan). The difference in early mortality for a primary-Fontan operation (16%) compared with a completion-Fontan operation (7%) is substantial (p < 0.05). Since January 1991, mortality associated with the hemi-Fontan operation has been 5.5% (7 deaths in 127 patients). A systematic staged approach to Fontan's operation has been undertaken with a hemi-Fontan operation in patients who are 6 months of age and a completion Fontan operation when those patients are 12 to 18 months of age in an effort to reduce the volume load of the ventricle as early as possible, to minimize intermediate mortality from the palliated state, and to reduce the impact of rapid changes in ventricular geometry and diastolic function that can accompany either the hemi-Fontan or primary Fontan operation, but that are lethal only after a primary Fontan operation.

Heart Defects, Congenital↗
PubMed1993

The relation between clinical manifestations of polycystic ovary syndrome and beta-cell function.

OBJECTIVE: Hyperandrogenism in patients with polycystic ovary syndrome has been shown to correlate with hyperinsulinaemia of insulin resistance. We have investigated if basal levels of insulin and the response to the intravenous administration of glucagon can reveal insulin resistance in patients with polycystic ovary syndrome. PATIENTS: Nine obese (BMI > 25 kg/m2) and nine non-obese (BMI 19-25 kg/m2) women with PCOS, chosen from a population of 91 women attending the infertility clinic, and 19 normally cycling women (seven obese, 12 non-obese) were studied. Oligo or amenorrhoea, hirsutism, and 12 or more follicles in a given ovary were selection criteria. MEASUREMENTS: Glucagon, 1 mg, was given intravenously to 18 of the 91 women and to the control subjects. Blood was taken at -5, 0, 5, 10 and 15 minutes for measurements of integrated areas under the response curve for insulin, C-peptide and glucose, respectively. Basal blood samples were drawn for fasting insulin, C-peptide, glucose, testosterone, sex hormone-binding globulin (SHBG), free fatty acids and IGF-I measurements. The free androgen index was calculated according to the formula FAI = testosterone x 100/SHBG. RESULTS: There were no significant differences in maximal increment and area under the response curve for glucose, C-peptide and insulin. FAI was significantly higher in all patients with features of polycystic ovary syndrome. However, fasting insulin levels were significantly higher only in obese patients when compared with obese control subjects and lean patients. CONCLUSIONS: The administration of 1 mg glucagon i.v. did not distinguish patients with polycystic ovary syndrome from control subjects. The mild insulin resistance of polycystic ovary syndrome is related only to obesity and is therefore unlikely to play an important role in the hyperandrogenism associated with the syndrome.

Adult↗
PubMed1992

Fontan procedure for hypoplastic left heart syndrome.

Since 1985, 354 neonates have undergone palliative reconstruction for hypoplastic left heart syndrome with 109 early deaths and 12 late deaths. Of the survivors, before 1989, 77 patients underwent a subsequent modified Fontan operation, consisting of baffling the atrial septal defect to the tricuspid valve (initial 25 patients) or intraatrial baffling of the inferior vena cava to the pulmonary arteries and superior vena cava (52 patients). There were 17 early deaths and three late deaths. Major serous effusions developed in 42 patients (54%) after Fontan operation. Since 1989, a staged approach to Fontan's operation was undertaken in an effort to reduce the volume load of the right ventricle as early as possible, to minimize the impact of rapid changes in ventricular geometry and diastolic function that can accompany a primary Fontan operation, and to reduce effusive complications. Thus, at a mean age of 6 months, 121 patients have undergone closure of aortopulmonary shunt, augmentation of central pulmonary arteries, and association of the superior vena cava with the branch pulmonary arteries (hemi-Fontan procedure). Of these, 61 patients have already undergone completion of the Fontan procedure with six early deaths and three late deaths. Major serous effusions developed in 28 patients (46%) with the staged Fontan. For perspective, the contemporary experience since January 1991 consists of 58 neonates who have undergone initial palliation with 11 deaths (19%), 17 patients who have undergone the hemi-Fontan procedure with one death (6%), and 21 patients who have undergone completion of the Fontan operation with one death (5%).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗
PubMed1992

Carbon dioxide prevents pulmonary overcirculation in hypoplastic left heart syndrome.

Circulatory and metabolic homeostasis in patients with hypoplastic left heart syndrome is dependent on a delicate balance between systemic and pulmonary blood flow. Hypocarbia can result in a marked decrease in pulmonary vascular resistance accompanied by pulmonary overcirculation, systemic hypotension, metabolic acidosis, and death. This report illustrates that early and precise control of the arterial carbon dioxide tension using inspired carbon dioxide can be effective in preventing or treating instability arising during management of a patient with hypoplastic left heart syndrome.

Acidosis, Respiratory↗
PubMed1990

Pediatric heart transplantation.

Since the introduction of cyclosporine in the early 1980s, there has been a surge of activity in the field of pediatric heart transplantation. Careful patient selection has resulted in operative and short-term patient survival comparable to that achieved in adult transplant programs. The results of neonatal heart transplantation have been exciting and encouraging; neonates may require less immunosuppressive therapy than older infants and children. Transplantation clearly offers the chance of survival and significant rehabilitation to children with end-stage heart disease. Long-term management issues include the effects of chronic immunosuppressive therapy on growth and development and renal function, and the time-related risk of rejection, infectious complications, neoplasms, and graft atherosclerosis.

Child↗
PubMed1988

The automatic implantable cardioverter-defibrillator: efficacy, complications and survival in patients with malignant ventricular arrhythmias.

Ninety-four patients underwent surgery for automatic implantable cardioverter-defibrillator implantation. Ninety patients were discharged from the hospital with the device and were followed up for a mean period of 17 +/- 10 months. Forty-six patients experienced at least one discharge of the device under circumstances consistent with a malignant ventricular arrhythmia. One sudden death occurred. Complications included perioperative death (3 patients), post-operative ventricular tachycardia (12 patients) and atrial fibrillation (8 patients), perioperative myocardial infarction (1 patient) and device discharges for sinus tachycardia and supraventricular arrhythmias (17 patients). Six and 12 month survival rates by life table analysis were 98.7 and 95.4%, respectively. Thus, the automatic implantable cardioverter-defibrillator is a highly effective and relatively low risk treatment modality for patients with refractory life-threatening ventricular arrhythmias.

Adolescent↗