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Biomedical subjects

G A Berg

Publications and source records attributed to G A Berg.

At least 19 recordsLinked to original sources
PubMed2006

Vascular function in patients with end-stage renal disease and/or coronary artery disease: a cardiac magnetic resonance imaging study.

Decreased arterial compliance in end-stage renal disease (ESRD) is associated with increased cardiovascular risk. Our aim was to examine aortic compliance in patients with ESRD using cardiac magnetic resonance imaging (MRI) and to compare these with patients with advanced atherosclerotic disease who are known to be at high cardiovascular risk. We examined a total of 83 subjects matched for age: 24 had ESRD and were on dialysis therapy for 3+/-6 years, 24 had severe coronary artery disease (CAD), 11 had both ESRD and CAD (4+/-5 years on dialysis therapy), and 24 healthy subjects with no evidence of CAD. Vascular and cardiac function was assessed using cardiac MRI. Aortic compliance was significantly reduced in patients with CAD compared to control subjects (11.3+/-6.3 ml x 10(-3)/mm Hg vs 15.6+/-6.0 ml x 10(-3)/mm Hg, P=0.009). Patients with ESRD also exhibited significantly reduced aortic compliance compared to healthy controls (12.4+/-5.8 ml x 10(-3)/mm Hg vs 15.6+/-6.0 ml 10(-3)/mm Hg, P=0.012), whereas there was no significant difference in aortic compliance between patients with CAD and ESRD. Even in the absence of symptomatic CAD, patients with ESRD have significantly reduced aortic compliance compared to normal subjects. Patients with ESRD have equivalent aortic compliance to patients with advanced CAD. These findings suggest that a significantly reduced aortic compliance is one of many mechanisms promoting premature cardiovascular events in patients with ESRD compared to age-matched controls from the general population.

Aged↗
PubMed2006

Metabolic syndrome throughout the menopausal transition: influence of age and menopausal status.

OBJECTIVE: To assess the relationship between the main components of both the metabolic syndrome and insulin resistance and menopausal status in the menopausal transition. METHODS: A total of 124 healthy women were divided into four groups according to their menstrual status: the first group consisted of 35 women in menopausal transition with menstrual bleeding (MTM) and with cycles between 35 and 80 days; the second group was composed of 29 women in menopausal transition with 3-6 months of amenorrhea (MTA). The third group consisted of 31 postmenopausal women (PostM) and the fourth group of 29 premenopausal women (PreM) with regular cycles. The metabolic syndrome was evaluated following the ATP III criteria. Evaluation of insulin resistance was made through the HOMA, QUICKI and McAuley indices and the triglycerides/high density lipoprotein (HDL) cholesterol ratio. RESULTS: The triglycerides/HDL cholesterol ratio increased in MTM, MTA and PostM women in comparison with PreM women. A slight decrease in the QUIKI index (p = 0.06) and a decrease in the McAuley index (p < 0.001) were observed in MTM, MTA and PostM women in comparison to PreM women. The relative frequencies of metabolic syndrome in the four groups were: PreM, 0%; MTM, 20%; MTA, 21%; and PostM, 22% (p = 0.0001). The most frequent markers of the metabolic syndrome were increased waist circumference, low HDL cholesterol levels and hypertension. Linear regression between menopausal status and metabolic syndrome was lost when age was added to the model. CONCLUSIONS: The frequency of metabolic syndrome increased from the time of the menopausal transition to the postmenopause. Abdominal obesity was the most frequent feature observed. Nevertheless, aging erased the effect of the menopause on the metabolic syndrome. In order to prevent cardiovascular disease, the metabolic syndrome must be evaluated from the time of the menopausal transition.

Adult↗
PubMed2001

The aortic Elan stentless aortic valve: excellent hemodynamics and ease of implantation.

The superior performance of stentless aortic valves with improved left ventricular hypertrophy regression and greater effective orifice area is proven. The Aortech Elan stentless valve (AESV) is a glutraldehyde preserved porcine valve with a pericardial reinforced inflow tract and a scalloped outflow to reduce bulk. We present the early results of AESV implantation at our institution. The first 41 consecutive recipients of the AESV at our unit, between November 1999 and December 2000, were studied. Mean preoperative New York Heart Association functional class (NYHA) status was 3.00 +/- 0.1. Patients requiring a bioprosthesis with suitable anatomy routinely received this implant. The AESV was implanted, either with an interrupted or continuous suture to the inflow tract and a continuous suture to the outflow tract. Transthoracic echocardiography was performed at 6 to 9 weeks after surgery, and aortic transvalvular gradients, flow velocities, and effective orifice areas (EOA) were calculated. In the early postoperative period, two patients with coronary artery disease died of low cardiac output. Echocardiography demonstrated competent valves. At follow-up, one patient was shown to have mild to moderate perivalvular leak with minimal symptoms. Two patients with aortic regurgitation secondary to bacterial endocarditis had no evidence of infection at 3 months after surgery. Mean transvalvular gradient was 6.91 +/- 0.87 mm Hg and mean effective orifice area was 1.18 +/- 0.04 cm(2)/m(2) at a mean of 8.4 weeks after surgery. AESV recipients for native aortic endocarditis were free from infection and regurgitation. The Elan stentless aortic valve demonstrates excellent early hemodynamic results, with very low transvalvular gradients, good flow characteristics and low regurgitation incidence. Ease of implantation is evidenced by favorable ischemic times. This valve may offer an option to homograft in acute aortic endocarditis. Long-term results are awaited.

Aged↗
PubMed2001

Six-year follow-up of the Toronto stentless porcine valve.

Stentless valves in the aortic position have been shown to have superior hemodynamic performance to stented valves and have now been shown to increase survival. We report the medium-term results from a single center of 229 Toronto (SPV) aortic valve replacements between 1994 and 2000. The mean age of the patients was 72 years (range, 41-87 years). The mean Euroscores were 6.2 (+/-0.13) and Parsonnet scores of 16.8 (+/-0.5). Concomitant coronary artery bypass grafting was performed in 125 (55%) of patients, eight patients had additional mitral valve replacements and ten were redo procedures. Hospital mortality was 3.5%. The mean follow-up period was 45 (7-81) months. The actuarial survival was 92.4% (+/-1.4%) at one year and 76.2% (+/-3.5%) at five years. There were 37 late deaths (4.7% per patient years). There were 3 patients with prosthetic valve endocarditis (0.38% per patient years), two of whom died. Stroke occurred in 13 patients (1.6% per patient years), five of whom died. None of these events were known to be valve related. There was no incidence of structural valve dysfunction and no valves have been explanted. At follow-up, the mean transvalvular gradient was 4.2 mm Hg (range, 0.9-12.7 mm Hg). No aortic incompetence (AI) was seen in 88% of patients with trivial or mild AI in 11% of patients and moderate AI in one patient. This series shows acceptable early and medium-term results in an elderly population with a high incidence of coronary artery disease.

Adult↗
PubMed2000

Investigation into the sources of superoxide in human blood vessels: angiotensin II increases superoxide production in human internal mammary arteries.

BACKGROUND: Increased vascular superoxide anion (.O(2)(-)) production contributes to endothelial dysfunction and hypertension in animal models of cardiovascular disease. Observations in experimental animals suggest that angiotensin II (Ang II) increases.O(2)(-) production by activation of vascular NAD(P)H oxidase. We studied the sources of.O(2)(-) production in human blood vessels and investigated whether, and by what mechanism, Ang II might alter vascular.O(2)(-) production. METHODS AND RESULTS: Internal mammary arteries (IMAs) and saphenous veins (SVs) were collected at the time of cardiac surgery. Vessels were incubated in Krebs buffer at 37 degrees C.O(2)(-) was measured by lucigenin chemiluminescence. Basal. O(2)(-) concentrations were greater in IMAs than SVs. Inhibitors of NAD(P)H oxidase (10 micromol/L to 200 micromol/L diphenyleneiodonium) and xanthine oxidase (1 mmol/L allopurinol) caused reductions in.O(2)(-) concentrations in both IMAs and SVs. Western blotting of superoxide dismutase proteins demonstrated similar expression in IMAs and SVs. Vessels were also incubated in the presence or absence of Ang II (1 pmol/L to 1 micromol/L). Ang II increased.O(2)(-) production in IMAs at 4 hours of incubation (control, 978+/-117 pmol. min(-1). mg(-1); 1 micromol/L of Ang II, 1690+/-213 pmol. min(-1). mg(-1); n=27, P=0.0001, 95% CI 336, 925) but not in SVs. This effect was completely inhibited by coincubation of IMAs with DPI (100 micromol/L), a nonspecific Ang II antagonist ([sar(1), thre(8)]-Ang II, 1 micromol/L) and a specific Ang II type 1 (AT(1)) receptor antagonist (losartan, 1 micromol/L). Conclusions-. O(2)(-) production is greater in human IMAs than in SVs. NAD(P)H oxidase and xanthine oxidase are sources of.O(2)(-) production in these vessels. The vasoactive peptide Ang II increases.O(2)(-) production in human arteries by an AT(1) receptor-dependent mechanism.

Aged↗
PubMed1999

Lipoprotein alterations, abdominal fat distribution and breast cancer.

Plasma lipid profile and abdominal obesity have been associated with breast cancer risk, however published results have been inconsistent. To clarify these associations we studied lipid and lipoprotein alterations, obesity degree and body fat distribution, in 30 newly diagnosed breast cancer patients without treatment and 30 controls matched by age and menopausal status. Both pre and postmenopausal breast cancer patients presented higher body mass index, waist/hip ratio and insulin levels than their matched controls. An increase in triglycerides and a decrease in HDL-cholesterol, especially in the HDL2 subfraction, were observed in patients with breast cancer. Besides, HDL particle from these patients showed increased apo A1/HDL-cholesterol ratio. These alterations were correlated with waist/hip ratio. The association between lipoprotein alterations and abdominal obesity independent of menopausal status, in untreated newly diagnosed breast cancer patients is reported for the first time in this study.

Abdomen↗
PubMed1999

Randomized controlled trial of stented and stentless aortic bioprotheses: hemodynamic performance at 3 years.

A randomized prospective trial was undertaken to compare the hemodynamic performance and left ventricular regression after aortic valve replacement with the Toronto SPV stentless bioprosthesis and the Carpentier Edwards SAV (CE) bioprosthesis. Forty patients were randomized after the annular and sinotubular diameters had been measured. Early hemodynamic measurements were made with a thermodilution cardiac output catheter, and echocardiography was used thereafter. Left ventricular mass was assessed using magnetic resonance imaging (MRI) at 1 week, 6 months, and 32 months. The mean annular size was 25.3+/-2.2 mm (CE) and 25.5+/-1.5 mm (Toronto), although it was possible to implant valves with a mean diameter 3 mm larger in the stentless group (26.0+/-1.7 mm cf. 23.0+/-1.7 mm). Hemodynamic performance in the first 24 hours showed no significant difference between the groups, but there was a trend for shorter ventilation time and shorter stays in the intensive therapy unit in the stentless group. Echocardiography showed superior transvalvular gradients in the stentless group at 1 week (mean 5.5+/-3.1 mm Hg cf. 8.9+/-2.5 mm Hg), and this difference was maintained at a mean follow-up time of 32 months (3.5+/-0.6 mm Hg cf. 6.3+/-0.6 mm Hg). Similar regression of left ventricular mass was seen in both groups at 6 months, but at 32 months, measurement in diastole showed a reduction of 38% (P<.01) in the stentless group compared with 20% (P = ns) in the stented group, and measurements in systole showed a 23% (P<.01) and 13% (P = ns) reduction, respectively. This study confirms that a larger stentless valve can be implanted into a given size of aortic annulus with superior residual aortic valve gradients. These lower gradients seem to result in improved long-term regression of left ventricular mass as measured by MRI.

Aged↗
PubMed1998

A three year experience with the toronto stentless porcine valve.

In the three year period from March 1994, 112 Toronto Stentless Porcine Valves (SPV TM) were implanted in the Western Infirmary, Glasgow. There were 55 males and 57 females aged between 45 and 86 years (mean 70.9 +/- 7.2 yrs). The mean preoperative aortic gradient was 89 +/- 27 mmHg. Fifty-three patients (47%) had an isolated first time aortic valve replacement. Myocardial revascularisation was carried out in 51 patients (46%) with a mean of 1.7 +/- 0.9 coronary bypass grafts per patient. Six patients (5.3%) had associated mitral valve procedures and six patients (5.3%) had previous open heart surgery. Four patients (3.6%) had a minimally invasive procedure. There was one perioperative death (0.9%) which was not valve related. Of the 111 survivors there were three late deaths (cerebrovascular accident at two months and congestive cardiac failure at two months and four months). Two patients developed prosthetic valve endocarditis at three and five months respectively, one requiring a repair of a periprosthetic leak. To compare the effects of stented and stentless prostheses on early haemodynamic function and late left ventricular mass regression, a prospective randomized clinical trial was conducted. Following valve sizing, 20 patients were randomized to receive a Carpentier-Edwards SAV stented bioprosthesis (mean annular size-25.3 mm, mean valve size-23 mm) of which eight also had bypass grafts. Twenty patients were randomized to receive a Toronto SPV (mean annular size-25.5 mm, mean valve size-26 mm) of which nine had bypass grafts. The stentless valve group had a longer ischaemic time (77.9 +/- 20.9 min v 60.9 +/- 21.9 min) and bypass time (101.7 +/- 27.1 min v 82.9 +/- 20.2 min). Using continuous cardiac output monitoring, no statistically significant differences were found in early haemodynamic indices although the stentless group required less inotropes and had a shorter ventilation time (16.1 +/- 4.2 hrs v 55.2 +/- 104.9 hrs) and intensive care stay (1.1 +/- 0.2 days v 4.6 +/- 8.3 days). Mean and peak aortic gradients one week postoperatively were lower in the stentless group (5.6 +/- 3 mmHg v 8.9 +/- 2.3 mmHg and 12.5 +/- 7.8 mmHg v 24.4 +/- 8.8 mmHg respectively). Magnetic resonance imaging at six months showed a 15% reduction in the end systolic muscle mass index in the stented group but a greater reduction of 29% in the stentless group. This study shows that despite requiring a more demanding technique of insertion, aortic valve replacement with the Toronto stentless porcine valve can produce satisfactory early clinical results.

Aged↗
PubMed1996

The benefits of active rewarming after cardiac operations: a randomized prospective trial.

We conducted a prospective, randomized trial of three methods of rewarming patients after hypothermic cardiopulmonary bypass. Patients underwent either coronary artery bypass grafting or first-time valve replacement and were cooled to 32 degrees C during bypass. No significant differences existed among the groups as regards operative or preoperative parameters including hemodynamics and blood use. The patients actively warmed with a convective (Bair Hugger system, 3 hours) or a conductive blanket (electric overblanket, 4 hours) reached normothermia more quickly than those warmed with the space blanket (7 hours). This was reflected in significantly earlier extubation in the former two groups: Bair Hugger system 10.8 +/- 0.6 hours, electric blanket 11.3 +/- 1.0 hours, and space blanket 14.8 +/- 0.8 hours. Patients warmed with the space blanket required a higher dosage of morphine over the first 12 hours than those warmed with the electric blanket (10.4 vs 6.5 mg; p = 0.004), which may account for some of the differences between these two groups. No differences could be demonstrated between the two active blankets. On economic grounds we therefore recommend the reusable electric blanket for routine use.

Aged↗
PubMed1996

Emergency bypass without bypass!

We present 2 cases of failed coronary angioplasty, with hemodynamic compromise, where emergency coronary artery bypass grafting was performed without cardiopulmonary bypass. The hypodynamic nature of the stunned myocardium in this circumstance allows this technique to be applied with relative ease to accessible vessels. As a consequence, reduced morbidity and hospital stay can be anticipated.

Aged↗
PubMed1993

Arrhythmia prophylaxis after coronary artery surgery. A randomised controlled trial of intravenous magnesium chloride.

One hundred and thirty patients undergoing elective myocardial revascularisation were randomised to receive an intravenous infusion containing either 50 mmol magnesium chloride or placebo during the first 48 h following surgery. Magnesium was given to 66 patients and a placebo infusion to 64 patients. Postoperative serum magnesium concentrations fell in the placebo group (from 0.83 +/- 0.06 to 0.79 +/- 0.11 mmol/l) but were elevated in the magnesium group (from 0.82 +/- 0.05 to 1.2 +/- 0.25 mmol/l). In total, 35 patients (26.9%) had a supraventricular arrhythmia, of which 11 were in the magnesium group (16.7%) and 24 (37.5%) in the placebo group (P = 0.013). Three patients in the magnesium group had an episode of ventricular fibrillation and three patients in the placebo group had frequent ventricular ectopics. There was one death in the magnesium group associated with a perioperative myocardial infarction. This study shows that intravenous magnesium supplements reduce the incidence of supraventricular arrhythmias following coronary artery surgery.

Aged↗
PubMed1988

Mechanical versus biological heart valves: a ten-year comparison in a single centre.

Between January 1977 and December 1986, 1606 Bjørk-Shiley tilting disc prostheses (BS) and 1346 Carpentier Edwards porcine prostheses (CE) were implanted in 1300 and 1156 patients, respectively, at the same institution. During the time of implantation, both valves have developed: the BS through standard disc and convexo-concave to monostrut, and the CE valves from standard to supra-annular. Newer valve types were used where applicable as they became available. Preoperative status in respect of age and cardiac rhythm were similar. There were significantly more females (64% BS: 54% CE, P less than 0.001); worse NYHA grade (74% Grade 111 and IV-BS: 56% 111 and IV-CE, P less than 0.001) more closed heart surgery (26% BS: 18% CE, P less than 0.001) and more previous open heart surgery (11.6% BS: 8.9% CE, P less than 0.001) in the BS group. All BS patients were anticoagulated and 49% of mitral CE patients and 7% of aortic CE patients were anticoagulated. There was no significant difference between the two groups in hospital mortality (BS 7.2%: CE 6.3%), late mortality (BS 2.5%/patient year: CE 3.2%/patient year) overall incidence of systemic embolism (BS 1.3%/patient year: CE 1.4/patient year), prosthetic valve endocarditis (BS 0.7%/patient year: CE 0.9%/patient year), valve failure (BS 0.5%/patient year: CE 0.9%/patient year) or peri-prosthetic leak (BS 1.2%/patient year: CE 1.3%/patient year). The incidence of systemic embolism in the aortic position was lower with the BS prosthesis (BS 0.2%/patient year: CE 1.2%/patient year, P less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Management of an infected pseudoaneurysm following an aortoventriculoplasty.

An 11-year-old child developed prosthetic valve endocarditis with associated infection of the prosthetic and pericardial patches 6 months following an aortoventriculoplasty. Angiography revealed an associated false aneurysm which communicated with both the ascending aorta and the right ventricular outflow tract. This report discusses the surgical management of this patient.

Aneurysm, Infected↗
PubMed1987

Sudden coronary death in Glasgow: nature and frequency of acute coronary lesions.

A detailed pathological study of the coronary arteries was carried out on 130 random white subjects (91 male and 39 female) who died suddenly in the Glasgow area. In 30 there was a clearly defined cause of death that was not due to ischaemic heart disease. In eight subjects the cause of death was in doubt. Ninety two of the 130 showed coronary stenosis resulting in a loss of more than 75% of coronary artery cross sectional area and/or acute coronary events with no other cause of death. Of these 92 subjects considered to have died suddenly of ischaemic heart disease, 64% showed plaque rupture and thrombosis which occurred at sites of previous high grades of stenosis. Twenty two subjects had intraluminal thrombosis unrelated to plaque fissuring. Thirty eight (41%) showed histological evidence of recent myocardial necrosis; acute coronary events occurred in 34 of these. There was no correlation between the duration of symptoms before death and the occurrence of acute coronary events. Acute coronary events, mainly in the form of plaque rupture, are a common finding in sudden coronary death when a careful study is made of the whole coronary arterial tree.

Acute Disease↗
PubMed1987

Sudden coronary death in Glasgow: the severity and distribution of chronic coronary atherosclerotic stenoses.

A detailed analysis of the extent of coronary artery atherosclerosis was made in 92 white subjects (66 men and 26 women) who died suddenly from ischaemic heart disease. Stenoses resulting in loss of greater than or equal to 75% of luminal cross sectional area (significant stenosis) were found in 90 subjects and these were more extensive in the proximal coronary tree than in the distal. Thirty nine per cent had triple vessel disease, 37% had double vessel disease, and 23% had single vessel disease. In addition one man had an isolated significant stenosis affecting the left main coronary artery. The frequency of significant stenoses in the left main coronary artery was greater in men than in women. The arteries that were least affected were the distal branches of the right coronary artery. A notable feature was the widespread nature of the coronary atherosclerosis: only 26 of the total of 1840 segments of coronary artery examined in the 92 victims could be described as having a normal intima (less than or equal to 10% loss of the area within the internal elastic lamina).

Adult↗