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Biomedical subjects

H Oelert

Publications and source records attributed to H Oelert.

At least 127 records · Page 7Linked to original sources
PubMed1992

Effects of tolazoline and prostacyclin on pulmonary hypertension in infants after cardiac surgery.

OBJECTIVE: To evaluate the hemodynamic effects of tolazoline and prostacyclin in infants with pulmonary vasospasm after cardiac surgery. DESIGN: Prospective cohort study. SETTING: Pediatric ICU. PATIENTS: The cohort consisted of 42 infants and children with congenital heart disease and pulmonary hypertension who underwent corrective surgery and were monitored postoperatively using pulmonary artery catheters. Fourteen infants (2 to 12 months old) in this group required postoperative treatment with tolazoline or prostacyclin. INTERVENTIONS: Tolazoline was administered as a bolus of 0.5 mg/kg for treatment of persistent pulmonary hypertension or acute pulmonary hypertensive crisis. If its effectiveness was proved after 30 mins by hemodynamic measurements, a continuous iv infusion of 0.5 mg/kg/hr was established. Higher doses of tolazoline were avoided. If tolazoline treatment did not fulfill the criteria for pulmonary vasodilation, prostacyclin was given by continuous iv infusion at a starting rate of 5 ng/kg/min, followed by 10 ng/kg/min. In three patients, the infusion rate was increased to 15 ng/kg/min. RESULTS: Bolus administration of tolazoline resulted in a distinct pulmonary vasodilation in seven infants: mean pulmonary artery pressure and pulmonary vascular resistance decreased by an average of 35% and 45%, respectively. In these patients, tolazoline was infused over the following 12 to 72 hrs. One infant who received tolazoline for 72 hrs developed a clinically important gastrointestinal hemorrhage. In seven nonresponders to tolazoline, prostacyclin (PGI2) at an infusion rate of 5 ng/kg/min led to pulmonary vasodilation in five patients, at an iv infusion rate of 10 ng/kg/min in all seven infants studied. The latter dose of PGI2 reduced the mean pulmonary artery pressure by an average of 37%, and pulmonary vascular resistance by 43%. Transient withdrawal of prostacyclin in five infants demonstrated its short half-life and clinical effectiveness. Apart from a facial flush, no side-effects were encountered using PGI2 as an infusion over durations ranging from 12 to 504 hrs. CONCLUSIONS: These data suggest that, if tolazoline in a relatively low dose proves to be inefficient, prostacyclin can still be used as a safe and effective drug for treatment of pulmonary vasospasm. Prostacyclin offers more than a pharmacologic alternative to increased tolazoline dosages.

Drug Evaluation↗
PubMed1992

[Revascularization of heterotopic isotransplants of the rat trachea using an omentum flap].

Donor airway ischemia remains a significant problem following lung transplantation. An acceleration of local bronchial revascularization would be advantageous for bronchial healing. In the present study, the quantitative effects of omentopexy on tracheal revascularization and epithelial regeneration were investigated in a heterotopic rat tracheal isograft model. Tracheal segments were harvested from donor rats and heterotopically implanted into the omentum of syngeneic recipient rats. Tracheal segments were wrapped for 2 days (group 2), 7 days (group 3) or 14 days (group 4). Tracheal segments in group 1 were harvested and not re-implanted. Following sacrifice of the animals after 2, 7 or 14 days, the vascularity of the tracheas and the tracheal epithelial morphology were assessed histologically using morphometric image analysis. The vascularity of tracheal segments was significantly higher in group 1 (native tracheas) compared to all other groups. Vascularity in group 4 segments (omental wrap for 14 days) was significantly greater than in group 3 segments (omental wrap for 7 days). Tracheal epithelial morphology was characterized by non-confluent single epithelial cells at day 2, a confluent multilayered nonciliated epithelium after 7 days of omental wrap and a morphologically normal epithelium after 14 days of omental wrap. Our new heterotopic rat tracheal isograft model allows histologic assessment and quantification of local revascularization and epithelial regeneration of tracheal segments by omentopexy.

Anastomosis, Surgical↗
PubMed1991

Evaluation of the healing of precoated vascular dacron prostheses.

Knitted and woven Dacron grafts commercially coated with bovine collagen, gelatin and human albumin were implanted end-to-side between the infrarenal aorta and the bifurcation in 35 growing pigs. Grafts were explanted after 4, 8 and 12 weeks and compared to 6 uncoated knitted prostheses preclotted with blood that served as a control. Uncoated grafts rapidly developed a firmly attached neointima lined with endothelium. Compared with coated grafts the thrombus-free area of uncoated grafts was significantly larger (P less than 0.05). The slow resorption of albumin resulted in a delayed and incomplete neointimal healing and failing graft incorporation. Although the bovine collagen was only minimally cross-linked by formaldehyde, healing of the neointima was compromised in a thin woven graft that demonstrated peeling of the inner capsule even after 12 weeks. The identical collagen as well as bovine gelatin were quickly degraded in knitted grafts and both types showed transprosthetic infiltration at 4 weeks. All knitted grafts coated with either collagen or gelatin, however, were occluded after 8 and 12 weeks. Light microscopy revealed hyperplasia of smooth-muscle cells within the thickened distal anastomotic region. These results demonstrate that a timely return of porosity is mandatory for the development and maintenance of an intact neointima. Both the structure of the fabric as well as the method of preparing the coating are crucial variables to determine the rate of biodegradation.

Animals↗
PubMed1991

PTCA of the left main stem following protective coronary artery bypass grafting.

Percutaneous transluminal coronary angioplasty (PTCA) was performed in 14 patients with significant left main stem stenosis following protective coronary artery bypass grafting (CABG). The procedure was successful in 13/14 patients (93%), achieving a decrease in mean diameter stenosis from 74% +/- 7% to 31% +/- 12% (P less than 0.01). Accordingly, the absolute stenosis diameter increased from 0.9 mm +/- 0.3 mm to 2.4 mm +/- 0.5 mm (P less than 0.01). Dissection of the left main stem artery and a transient significant fall of blood pressure each occurred in one patient. No other serious complications were noted. Eight of 13 patients (62%) with successful PTCA underwent control angiography. Restenosis had occurred in 3 of 8 patients (38%) with total occlusion of the left main stem in 1 patient. All bypass grafts were found to be patent at follow-up. Clinical evaluation in all 14 patients revealed no serious events (death, myocardial infarction, repeat revascularization procedure) during a mean follow-up period of 27 months (range 6-39 months). PTCA of the left main stem following CABG can be considered a relatively safe and effective procedure with a marked restenosis-rate but beyond that, an uncomplicated long-term follow-up.

Adult↗
PubMed1991

Resection of central primary pulmonary artery sarcoma.

Primary sarcomas of the pulmonary arteries are rare, and the diagnosis is in the majority of the reported cases established postmortem. Surgical resection of these centrally located tumors has been performed either by pneumonectomy and/or local tumor resection. We report on two patients with sarcomas of the central pulmonary arteries who underwent successful resection of the tumor and prosthetic replacement of the arteries under cardiopulmonary bypass. One patient required additional thromboendarterectomy of the right pulmonary artery branches because of secondary thrombus formation. As primary pulmonary artery sarcomas are refractory to both chemotherapy and radiation, surgical resection remains the only means of treatment. The prognosis depends entirely upon resectability, which, if necessary, should be performed with the aid of cardiopulmonary bypass. In this way, lung resection may be avoided.

Adult↗
PubMed1991

Identification of abscess formation in native-valve infective endocarditis using transesophageal echocardiography: implications for surgical treatment.

The object of the study was to follow patients with endocarditis-associated abscesses in order to evaluate the clinical outcome with and without surgical intervention. Transesophageal echocardiography successfully displayed the location and extent of abscess cavities in 14 patients (group A) with aortic valve endocarditis. The infective process was limited to the perivalvular tissue in two, extended into the ascending aorta in six, and included the interventricular septum, the right ventricular outflow tract, interatrial septum, and/or mitral valve annulus in six patients. The complication rate was significantly higher in group A than in group B, which consisted of 27 patients with proven signs of endocarditis but without endocarditis-associated abscesses. The complication rates were embolic events 64.3% in group A vs 29.6% in group B, need for surgery in 64.3% vs 18.5%, and death in 50.0% vs 3.7%, respectively. The duration of fever--as a marker of an active infective process--before diagnosis and the onset of adequate treatment was significantly higher in group A than in group B (46.7 +/- 8.4 days vs 7.7 +/- 2.6 days). Organisms were isolated in 71.4% in group A and in all patients of group B. Streptococcal infections were noted in A in 54.5% vs 44.4% in B., staphylococcal in 27.3% vs 40.7%. Initial surgical repair in 9 of 14 patients in A (64.3%) included nine aortic valve and one mitral valve prosthesis implantations, two aortic valve-annulus reconstructive procedures, one dacron patch closure, and three partial resections of the aorta ascendens with end-to-end anastomosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Abscess↗
PubMed1991

Healing parameters of a new albumin-coated knitted Dacron graft.

Knitted dacron grafts commercially coated with human albumin were implanted end-to-side between the infrarenal aorta and the bifurcation in 9 growing pigs. Uncoated knitted dacron grafts implanted in 6 pigs served as a control. Grafts were explanted after 4, 8, and 12 weeks and evaluated for neointimal healing, peeling of the inner and outer capsule, extent of neoendothelialization, absorption of the sealant, interstitial infiltration, and perigraft inflammation. Toxicological in-vitro analysis included the evaluation of residual aldehydes and plasticizers. In contrast to the uncoated knitted prosthesis, which rapidly developed a layered neointima with complete neoendothelialization, only islands of neointima were found in albumin-coated grafts after 4 weeks. The neointima remained incomplete at 8 and 12 weeks with scanning electron microscopic evidence of sharply demarcated endothelial areas. No transprosthetic bridging was detectable even after 12 weeks and peeling of the inner and outer capsule was easily provocable. These results outline that the cellular and connective infiltration of the prosthetic wall is compromised unless degradation of the sealant is completed within four weeks: the neointimal development is delayed and graft incorporation fails, leaving the outer capsule unattached.

Albumins↗
PubMed1990

[Intraoperative echocardiography--status and perspectives].

The transoesophageal echocardiography gives a new possibility of the continuous control of the ventricular function, of the valvular and subvalvular morphology and of haemodynamic abnormalities during anaesthesia and operation. It allows to obtain echocardiographic records during the whole operation of one and the same place without transducer and sound being sterile or other precautionary measures of the sterility being taken into consideration. Their use neither demands that the surgeon interrupts his work nor is he bound to the open thorax. The result of the operation can be controlled immediately after the surgical intervention and remaining defects can be made visible. Defects which are in direct connection with the surgical intervention and are established before the end of the operation should cause the surgeon to repeat or to continue the intervention for as long as the patient is still in the operating theatre. Intra- and postoperatively, the transoesophageal echocardiography puts, him into the place to apply a medicamentous therapy and/or circulatory assistancies and finally to delay the occlusion of the thorax or to perform the rethoracotomy. As a matter of experience two to three days later the operation wound can again be closed without much ado.

Adolescent↗
PubMed1990

Mediastinal lymph node staging with transesophageal echography in cancer of the lung.

Transesophageal echography (TEE) was used prospectively to study mediastinal lymph node enlargement in 23 patients with cancer of the lung. The findings were validated blindly by comparison with computed tomography (CT, n = 23) and pathological N classification after curative surgery (n = 9). Lymph nodes larger than 1 cm were defined as pathologically enlarged. In the upper mediastinum, 22% (8 vs 36), in the lower mediastinum including the subaortic region 112% (37 vs 33) and in the hilar region 67% (6 vs 9) of enlarged lymph nodes diagnosed by CT were detected by TEE. A pathological study in 9 patients demonstrated true positive findings in 2 vs 1, true negatives in 4 vs 5, false positives in 3 vs 2 and false negatives in 0 vs 1 comparing TEE with CT. From these preliminary data, we conclude that TEE, although still experimental, is equal or superior to CT in detecting enlarged nodes in the lower mediastinum, specifically in the aortopulmonary window but clearly inferior in the upper mediastinum and the hilar region. Additional information on central tumors and infiltration of the heart or great vessels can be clarified. In addition, data on hemodynamics and cardiac status can be obtained. TEE seems to be a promising tool in the preoperative staging of lung cancer.

Adult↗
PubMed1990

Surgical correction of a severely obstructed pulmonary artery bifurcation in Takayasu's arteritis.

A young male patient (NYHA III) presented with a severe pulmonary artery bifurcation stenosis of unknown origin. He underwent successful radical resection and endarterectomy of abundant endoluminal and perivascular inflammatory tissue. Surgery was performed with extracorporeal circulation (ECC) without transection of the aorta and the pulmonary artery bifurcation was enlarged with a patch. Right ventricular to peripheral pulmonary artery pressure gradient fell from 80 mmHg preoperatively to 25 mmHg 18 months postoperatively. The patient is fully rehabilitated and working (NYHA I). Histological examination confirmed Takayasu's arteritis as the underlying disease and medium-term follow-up angiography showed an almost normal pulmonary artery bifurcation. We conclude that the radical surgical approach is a valuable palliation in this disease.

Adult↗
PubMed1990

New bundle branch block after coronary artery bypass grafting--evaluation by CK-MB isoenzyme analysis and transoesophageal echocardiography.

Twelve patients with a new complete bundle branch block after coronary artery bypass grafting underwent transoesophageal echocardiography (TEE). The results of TEE were compared with the pre-operative ventriculography, CK-MB isoenzyme time-release curves and clinical course. In eight patients with transient right bundle branch block or bifascicular block, low CK-MB activities and an uncomplicated postoperative course, transoesophageal echocardiography showed no new segmental wall motion abnormalities apart from a paradoxical septal movement in five. A persistent right or left bundle branch block was associated with either elevated isoenzyme activities, transoesophageal echocardiographic evidence of new segmental wall motion disturbance or both in four patients. One patient died because of fatal arrhythmia and one suffered from a prolonged low cardiac output syndrome. A transient bundle branch block is usually a benign electrocardiographic finding. In case of a persistent bundle branch block associated with elevated CK MB isoenzymes, new left ventricular wall motion disturbances indicating a peri-operative myocardial injury are easily detected by transoesophageal echocardiography.

Aged↗
PubMed1990

In-vitro assessment of centrifugal pumps for ventricular assist.

Currently two major types of centrifugal pumps are commercially available for ventricular assist: the Biomedicus-cone (Group I) and the Centrimed-impeller pump (now Sarns 3M) (Group II). To compare them for blood trauma and hemolysis, an in-vitro experiment was designed with a Stöckert roller pump as a standard control (Group III). The in-vitro circuit was constructed consisting of a pump head, electromagnetic flow probe, polyvinyl chloride tubing and a reservoir, identical for all groups. Human ACD blood was used for priming and was circulated with a flow rate of 2 L/min for 24 h. Blood samples were taken at 0, 1, 3, 6, 12, and 24 h and zero control values were subtracted from the resulting data per time interval. Among the 16 parameters studied, a highly significant difference in favor of Group I was found for glutamate oxalacetate transaminase (GOT) and lactate dehydrogenase (p less than 0.0001) and for the free plasma hemoglobin (p less than 0.0001) after 12 and 24 h, respectively. The hemolytic index (Allen) again was lowest for group I in contrast to Groups II and III (0.012 versus 0.060 and 1.70) after 24 h. All other parameters studied did not render significant differences between the systems tested. The authors conclude that the Biomedicus pump currently is the least traumatic centrifugal pump for ventricular assist.

Blood↗
PubMed1990

[Extracorporeal circulatory assistance with centrifugal pumps in postcardiotomy low-output syndrome].

From 6/86 to 5/89 seven out of 1700 (0.4%) open heart patients had to be assisted with centrifugal pumps for postcardiotomy low cardiac output syndrome. In 4 cases a left ventricular assist device (LVAD) was used, one case each had a right ventricular assist device (RVAD), an extracorporeal membrane oxygenation (ECMO) and a biventricular assist device (BVAD) with ECMO and ultrafiltration. The last 3 patients were assisted non-pulsatile without intraaortic balloon counterpulsation (IABP) and no impairment of vital organ function was observed. Four out of 7 patients could be weaned from the assist device after a mean of 30 hours (0.5-48). Three patients became long-term survivors with 2 assisted non-pulsatile. Transesophageal echocardiography (TEE) was used to determine the timing for wean off and was found to be an important adjunct to the monitoring of filling--and systemic pressure.

Adult↗
PubMed1990

[Intraoperative diagnosis of the heart and great vessels--echocardiography].

Two-dimensional echocardiography including color Doppler techniques can be used for analysis of the morphology and function and of the blood flow of the heart and the great vessels. Epicardial echocardiography has the advantage of high resolution and multiple scan planes. The restriction to the intraoperative period is a clear disadvantage. In addition, the scan planes are difficult to standardize. Transesophageal echocardiography can be used for monitoring during the whole operative period but is restricted to horizontal and/or longitudinal scan planes. It is a non-contact procedure and thus, sterile conditions are not affected. For evaluation of surgical success, intraoperative echocardiography can be used for analysis in patients with congenital heart disease, mitral valve regurgitation, hypertrophic obstructive cardiomyopathy, and aortic dissection. Acute intraoperative revisions with a second extracorporal circulation period will avoid reoperation. In patients with coronary artery disease the flow within the bypass and also the status of the anastomosis can be scanned and may contribute to reduce the perioperative infarct rate. Intraoperative echocardiography needs additional costs and man power. Only after randomized comparative prospective studies have demonstrated that patients controlled by intraoperative echocardiography have a better outcome and prognosis than patients without intraoperative control this method will become routine in open-heart surgery.

Echocardiography↗
PubMed1989

Continuous monitoring of mixed venous oxygen saturation in infants after cardiac surgery.

Continuous mixed venous oxygen saturation (SvO2c) was measured in 16 infants immediately after cardiac surgery. A polyurethane 4F, dual channel catheter (Opticath, Modell U440, Oximetrix) with fiberoptic filaments was introduced into the pulmonary artery during cardiothoracic surgery. The catheters were left in place for an average of 67.5 h (range 27 h -125 h) and there were no catheter-related complications. Correlation between continuous in vivo SvO2 values and in vitro values was satisfactory (r = 0.85), whereas a correlation between SvO2c and arterial oxygen saturation (SaO2) was not found (r = 0.07). The sampled arterial lactate values were inversely correlated to the simultaneously measured SvO2c, but the correlation coefficient was only r = -0.4. There was an inverse correlation between SvO2c and arteriovenous oxygen content difference (Ca-vDO2) (r = -0.82), and a marked inverse correlation to the calculated oxygen utilization ratio (r = -0.97). Therefore SvO2c continuously reflects the overall balance between oxygen consumption and delivery, but the use of SvO2 as a predictor of blood lactate levels is unreliable. A further purpose of the present study was to demonstrate the clinical applications and to show the usefulness of SvO2c-monitoring; particularly as a surveillance and early warning system, as a guide for assessing therapy and its relevance in interpreting other monitored parameters. In our opinion continuous SvO2 measurement is a reliable and valuable indicator of cardiopulmonary function in the immediate post-operative period, even in infants with complicated repair of cardiac malformations.

Blood Gas Analysis↗