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Biomedical subjects

O Ormerod

Publications and source records attributed to O Ormerod.

18 recordsLinked to original sources
PubMed1995

Aortic valve replacement with the freestyle stentless xenograft.

We performed aortic valve replacement with the Free-style stentless xenograft in 55 consecutive patients requiring a bioprosthesis. Thirty-four were male and 21 female, and all were in New York Heart Association class III to V. Ages ranged from 44 to 87 years (median, 74 years). Fifteen patients required coronary bypass grafts. One required mitral valve replacement (after attempted repair) and another needed repair of both the mitral and tricuspid valves. Four were reoperations. Implantation involved two-thirds transection at the aortic sinotubular junction and insertion of the xenograft cylinder into the aortic sinuses. Ischemic times ranged from 34 to 58 minutes for isolated aortic valve replacement and up to 79 minutes for aortic plus mitral valve replacement. Two patients died in the hospital of left ventricular failure. Survivors underwent echocardiographic assessment of systolic gradients. The mean gradients for valve sizes of 21, 23, 25, and 27 cm were 13, 10, 8, and 6.5 mm Hg, respectively. No patient had more than trivial regurgitation. One died late of left ventricular failure. The Free-style stentless xenograft is user friendly and can be employed in a calcified root. The "cylinder within a cylinder" method is simple and reproducible and avoids aortic regurgitation. Follow-up has shown excellent hemodynamic function and decreasing gradients.

Adult↗
PubMed1995

Time-related hemodynamic changes after aortic replacement with the freestyle stentless xenograft.

BACKGROUND: The Freestyle valve is a porcine aortic root fixed with net zero pressure across the cusps and treated with the anticalcification agent alpha-aminooleic acid. We evaluated the hemodynamic function of this stentless valve. METHODS: We implanted the valve into 80 consecutive patients scheduled to receive a bioprosthesis. Sixty-nine patients were more than 70 years old and 14 had calcified aortic sinuses. The "cylinder within a cylinder" implantation technique was used. Twenty-seven patients received coronary grafts, and 3 had mitral repair. All patients were studied echocardiographically during week 1 and 41 were studied at 6 months. RESULTS: Median ischemic time for isolated aortic valve replacement was 44 minutes. There were four hospital deaths, none valve related. No patient had more than trivial aortic regurgitation. Mean systolic gradients for valve sizes 21 to 25 mm fell significantly with time (p < or = 0.05) due to remodeling of the porcine root and early regression of left ventricular hypertrophy. Late hemodynamic function was equivalent to an aortic homograft. CONCLUSIONS: The Freestyle valve is easily implanted and has excellent hemodynamics. Transvalvular gradients decrease progressively.

Adult↗
PubMed1994

An audit of cardiac surgery in patients aged over 70 years.

With an increasingly aged population, the number of patients requiring treatment for cardiovascular diseases will rise. Previous expectations of cardiac surgery in the over-seventies have been poor, with surgery being very much a last resort. We decided to test whether this was appropriate, and to determine whether the priority of surgery affected the outcome. Three hundred and six patients over the age of 70 were operated on in our unit in a 4 1/2-year period, 210 as elective operations and 96 as emergencies. Eighty-nine per cent were in NYHA class III-IV pre-operatively and half had other significant medical problems. Most (46%) underwent coronary artery surgery. The methods used were identical to those used for the younger patients in both operative approach and post-operative management. The overall mortality was 6.9%; 1.9% for elective procedures and 16.7% for emergencies (12.3% when catastrophic pathologies are excluded). However, the morbidity was not significantly different between the two groups and the length of post-operative ventilation and hospital stay were likewise not significantly different. Follow-up of the survivors showed no late deaths, and 87% were in NYHA class I and II. Of the others, 25 have required additional hospital admissions for associated cardiac problems. One required another invasive procedure (a PTCA), but none has required further surgery. The findings of low mortality for elective cardiac surgery in this age group are in agreement with other reports. If early referral prevents emergency surgery, it should be avidly pursued, in view of the improved outcome for elective surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Comparison of different methods for assessing sympathovagal balance in chronic congestive heart failure secondary to coronary artery disease.

Twenty-five patients (aged 62 +/- 2 years) with stable, moderate to severe ischemic congestive heart failure (CHF) (New York Heart Association class II/III: 15/10; ejection fraction 21.6 +/- 2%; and peak oxygen uptake 13.6 +/- 0.7 ml/kg/min) were studied to evaluate the ability of different methods to characterize autonomic tone in chronic CHF. Sympathovagal balance was assessed by: (1) heart rate variability in the time domain, assessed by the SD of RR intervals; (2) heart rate variability in the frequency domain, assessed by low- (0.03 to 0.14 Hz) and high- (0.18 to 0.40 Hz) frequency components of heart rate variability by autoregressive power spectral analysis; (3) 24-hour, daytime and nighttime heart rate; (4) submaximal heart rate during upright bicycle exercise, with respiratory gas analysis to obtain peak oxygen uptake; and (5) radiolabeled norepinephrine spillover. These methods did not correlate, with the exception of day and nighttime heart rate (r = 0.74; p < 0.001) and the expected inverse correlation between low and high frequency (r = -0.92; p < 0.001). No method correlated significantly with peak oxygen uptake, exercise tolerance or ejection fraction. After 8 weeks of physical training at home, all methods showed improvement in autonomic balance: increases in SD of RR intervals (+21%; p < 0.02) and high frequency (+41%; p < 0.007), and decreases in low frequency (-19%; p < 0.002), low-/high-frequency ratio (-48%; p < 0.03), norepinephrine spillover (-28.9%; p < 0.03), 24-hour heart rate (-2.7%; p < 0.005) and submaximal heart rate (-10.8%; p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Autonomic Nervous System Diseases↗
PubMed1992

Early and late changes in left ventricular filling after acute myocardial infarction and the effect of infarct size.

To characterize the early (1 week) and late (6 weeks) changes in left ventricular (LV) filling pattern associated with acute myocardial infarction (AMI) 45 patients (mean age 65 +/- 2 years) were studied by Doppler echocardiography. Based on clinical criteria, patients were divided into those with large (group L; n = 12) and those with small (group S; n = 33) infarcts and then compared with 16 age-matched control subjects. The following parameters were calculated from the mitral velocity waveform: (1) peak early and peak atrial velocities and their integrals; (2) peak early to atrial velocity ratio and velocity integral ratio; and (3) the pressure half-time of the early wave. One week after AMI, group L showed a decreased atrial and increased early velocity, velocity ratio and integral ratio, whereas the pressure half-time of the early wave was shorter than that in group S and in control subjects. At 6 weeks group L showed a reduction in early velocity, early to atrial velocity ratio and integral ratio, whereas pressure half-time increased. When groups S and L were combined there was a good inverse correlation between pressure half-time and infarct size as measured by peak enzyme release (r = -0.64, p < 0.001). These data suggest that, depending on infarct size, patients exhibit a "restrictive" filling pattern early after the acute event. This is manifested by the greater proportion of filling occurring in early diastole, reflecting an overall increase in chamber stiffness. At 6 weeks, this pattern is less pronounced presumably due to the remodeling process.

Aged↗
PubMed1992

Controlled trial of physical training in chronic heart failure. Exercise performance, hemodynamics, ventilation, and autonomic function.

BACKGROUND: Many secondary abnormalities in chronic heart failure (CHF) may reflect physical deconditioning. There has been no prospective, controlled study of the effects of physical training on hemodynamics and autonomic function in CHF. METHODS AND RESULTS: In a controlled crossover trial of 8 weeks of exercise training, 17 men with stable moderate to severe CHF (age, 61.8 +/- 1.5 years; left ventricular ejection fraction, 19.6 +/- 2.3%), increased exercise tolerance (13.9 +/- 1.0 to 16.5 +/- 1.0 minutes, p less than 0.001), and peak oxygen uptake (13.2 +/- 0.9 to 15.6 +/- 1.0 ml/kg/min, p less than 0.01) significantly compared with controls. Training increased cardiac output at submaximal (5.9-6.7 l/min, p less than 0.05) and peak exercise (6.3-7.1 l/min, p less than 0.05), with a significant reduction in systemic vascular resistance. Training reduced minute ventilation and the slope relating minute ventilation to carbon dioxide production (-10.5%, p less than 0.05). Sympathovagal balance was altered by physical training when assessed by three methods: 1) RR variability (+19.2%, p less than 0.05); 2) autoregressive power spectral analysis of the resting ECG divided into low-frequency (-21.2%, p less than 0.01) and high-frequency (+51.3%, p less than 0.05) components; and 3) whole-body radiolabeled norepinephrine spillover (-16%, p less than 0.05). These measurements all showed a significant shift away from sympathetic toward enhanced vagal activity after training. CONCLUSIONS: Carefully selected patients with moderate to severe CHF can achieve significant, worthwhile improvements with exercise training. Physical deconditioning may be partly responsible for some of the associated abnormalities and exercise limitation of CHF, including abnormalities in autonomic balance.

Autonomic Nervous System↗
PubMed1992

Thrombolysis and postinfarction ventricular septal rupture.

We studied all patients with postinfarction ventricular septal rupture referred to the Oxford Heart Centre for operation over a 4 1/2-year period. Twenty one women and 8 men were admitted to the Centre, 13 of whom had received streptokinase and 16 of whom had not. The median interval between symptomatic onset of myocardial infarction and the development of septal rupture was 24 hours for those treated by early thrombolysis (all streptokinase) and six days for those who were not. Of the 26 patients who underwent surgical repair, three were operated on less than 36 hours after streptokinase infusion, in one case within 12 hours of thrombolytic treatment. Macroscopic observation of the disintegrating myocardium showed muscle bundles dissected by blood rendered incoagulable by thrombolytic treatment, together with the histologic features of reperfusion injury. The overall surgical mortality rate for the streptokinase group was 33% and for the others 21%. The patient operated on within 12 hours of thrombolytic treatment recovered uneventfully. Six of seven surgical deaths were caused by left ventricular or biventricular failure and one by gastrointestinal hemorrhage. All survivors were in New York Heart Association classes II or III between 2 weeks and 4 1/2 years after operation. We conclude that thrombolysis leads to early breakdown of the interventricular septum after acute myocardial infarction but does not preclude early repair.

Aged↗
PubMed1991

Reversible T-wave abnormality in severe acute asthma: an electrocardiographic sign of severity.

Reversible electrocardiographic (ECG) abnormalities are well recognized in severe acute asthma. Inferior lead T-wave abnormalities have only rarely been reported, and their frequency and significance have not been well documented. We studied 70 consecutive patients with severe acute asthma on admission to hospital and during recovery, in order to examine the frequency and natural history of such changes and to document their relationship to the severity of the attack. Twenty-two patients (34%) had inferior lead T-wave inversion on ECGs performed within 1 h of admission (group 1), whereas the rest did not (group 2). Apart from sinus tachycardia this was the most common ECG abnormality. Patients with inferior T-wave inversion were found to have more severe asthma in terms of degree of pulsus paradoxus, peak expiratory flow rate, forced expiratory volume in 1 s and arterial blood oxygen tension. Ten group 1 and ten group 2 patients underwent two-dimensional echocardiography during the acute phase of their illness and during recovery. Six (60%) group 1 patients showed echocardiographic evidence of right ventricular pressure overload compared with only one (10%) patient in group 2 (P less than 0.02). Following recovery, voluntary hyperventilation and exercise testing in ten group 1 patients failed to reproduce the ECG changes seen on admission. Reversible inferior lead T-wave abnormalities may occur in the severe acute asthma and appear to be related to the severity of the attack.

Acute Disease↗
PubMed1984

Acute haemodynamic effects of oral prenalterol in severe heart failure.

The acute haemodynamic effects of oral prenalterol were studied in 14 patients with severe heart failure (NYHA class III) due to ischaemic heart disease. All had received treatment with digoxin, diuretics, and in most cases vasodilators. Prenalterol was administered at two hourly intervals to give cumulative doses of 20, 50, and 100 mg and mean plasma concentrations of 53, 97, and 175 nmol/l. Haemodynamic measurements were made two hours after each dose with Swan-Ganz catheterisation; cardiac output was measured by thermodilution. There were no significant changes in heart rate, mean arterial pressure, or pulmonary artery diastolic pressure after the drug. Cardiac index rose significantly after 50 mg and 100 mg prenalterol. Oral prenalterol has a beneficial short term haemodynamic effect in patients with severe heart failure. If this effect is sustained prenalterol may be of value in the long term management of patients with this disabling condition.

Adrenergic beta-Agonists↗
PubMedDate not supplied

Bisoprolol alone and in combination with amlodipine or nifedipine in the treatment of chronic stable angina.

Beta-blockers and calcium antagonists are both effective monotherapy for stable angina. When symptoms persist, these two agents are commonly co-prescribed in the hope that this combination has added benefit compared with monotherapy alone. We investigated the additional efficacy of the calcium antagonists amlodipine and nifedipine when added to bisoprolol in patients with stable angina. Patients were randomised in a multicentre, single-blind study, with crossover of three treatments consisting of bisoprolol 10 mg once daily, bisoprolol plus nifedipine 20 mg twice daily, and bisoprolol plus amlodipine 5 mg once daily. Exercise tests were performed at the end of each four-week study period and the exercise time to onset of angina was assessed. A total of 198 patients from 17 centres were recruited of whom 147 were evaluable for efficacy. There were no statistically significant differences in exercise duration to onset of angina between any of the groups. The combination of bisoprolol plus nifedipine was least well tolerated. In summary, this study suggests there is little benefit in adding a calcium antagonist to bisoprolol in treating patients with stable angina.

Adolescent↗