Contribution of nitric oxide to reactive hyperemia: impact of endothelial dysfunction

Our objectives were to (1) test the hypothesis that nitric oxide (NO) contributes to peak reactive hyperemia (RH) in the human peripheral vasculature, (2) examine the impact of atherosclerosis and its risk factors on RH, and (3) investigate whether L-arginine will improve RH in patients with endothelial dysfunction. The endothelium contributes to shear stress-mediated vasomotion by releasing a variety of dilating factors, including NO, but the contribution of NO to peak RH in patients with and without endothelial dysfunction is unknown. Endothelium-dependent and endothelium-independent function was assessed with intrafemoral arterial acetylcholine (ACh) and sodium nitroprusside. RH was produced by occlusion of blood flow to the leg for 3 minutes. The study was repeated after NG-monomethyl-L-arginine (L-NMMA) in 44 subjects and L-arginine in 9 patients with atherosclerosis. There were 15 normal control subjects without risk factors for atherosclerosis and 29 patients with risk factors or angiographic atherosclerosis. Microvascular vasodilation in response to ACh, but not to sodium nitroprusside, was lower in the patients with risk factors or atherosclerosis compared with normal control subjects, P=0.048, and the inhibition of ACh-induced microvascular dilation by L-NMMA was also greater in normal control subjects (P=0.045). Similarly, RH, including the peak response, was inhibited by L-NMMA in normal control subjects (P=0.0011) but not in patients with risk factors or atherosclerosis, suggesting that the contribution of NO to both ACh-induced dilation and RH was diminished in patients with risk factors or atherosclerosis. L-Arginine did not affect vasodilation in response to ACh, sodium nitroprusside, or RH. We concluded that (1) NO contributes to all phases of RH in the normal human peripheral vasculature, (2) patients with atherosclerosis or its risks have abnormal NO bioactivity in response to pharmacological and physiological stimulation, and (3) L-arginine does not improve RH in atherosclerosis. Reduced physiological vasodilation in atherosclerosis may contribute to or exacerbate hypertension and ischemia.

Patellofemoral contact forces and pressures during intramedullary tibial nailing

Patellofemoral joint forces and pressures were measured in a cadaver model during intramedullary nailing of the tibia. A significant increase in contact pressures was found at the lateral facet of the patellofemoral articulation using the medial paratendinous approach (P = 0.01) and at the medial facet when using the trans-patellar tendon approach (P = 0.001) to the proximal tibia. Increased contact pressures at the patello-femoral joint may result in chondral injury, which in turn may cause anterior knee pain, a common complication of tibial nailing.

Role of carbon fibre implants in osteochondral defects of the knee

Articular cartilage defects of the knee are a common condition diagnosed at arthroscopy. The management of these osteochondral lesions is controversial. We present our experience using carbon fibre implants to repair these defects in 18 patients. Eleven patients (61 per cent) had an osteochondral defect of the medial femoral condyle. Two patients had isolated patellar defects. The mean knee assessment and functional scores were 75 and 80 respectively using The Knee Society Clinical Rating System. Serial post-operative M.R.I. scanning revealed that there was no loss of implant position with an extensive local tissue response and good joint congruity. Overall, 11 patients (61 per cent) returned to their normal sporting activity, while 3 patients (18 per cent) had a poor result. One of these underwent a patellectomy. We conclude that carbon fibre implants may have a role to play in the management of osteochondral defects of the femoral condyles.

Aspirin improves endothelial dysfunction in atherosclerosis

BACKGROUND

The beneficial effects of aspirin in atherosclerosis are generally attributed to its antiplatelet activities, but its influence on endothelial function remains uncertain. We hypothesized that a cyclooxygenase-dependent constricting factor contributes to the endothelial dysfunction in atherosclerosis and that its action can be reversed by aspirin.

METHODS AND RESULTS

In 14 patients with coronary atherosclerosis and 5 with risk factors, we tested femoral vascular endothelial function with acetylcholine and substance P and endothelium-independent function with sodium nitroprusside before and after intravenous aspirin. Drugs were infused into the femoral artery, and Doppler flow velocity was measured. Acetylcholine-induced but not substance P-or sodium nitroprusside-induced vasodilation was lower in patients with atherosclerosis than in those with only risk factors. Aspirin had no baseline effect but improved acetylcholine-mediated vasodilation only in patients with atherosclerosis; at the peak dose, acetylcholine-mediated femoral vascular resistance index was 19 +/- 5%, P=.002 lower. There was a correlation between the baseline response to acetylcholine and the magnitude of improvement with aspirin (r=.5, P=.05). Thus, patients with a depressed response to acetylcholine had greater improvement with aspirin, and vice versa. The presence of atherosclerosis was an independent determinant of improvement with aspirin. Aspirin had no effect on the responses to either substance P or sodium nitroprusside.

CONCLUSIONS

Cyclooxygenase-dependent, endothelium-derived vasoconstrictor release modulates acetylcholine-induced peripheral vasodilation in patients with atherosclerosis. Improvement of endothelial dysfunction with aspirin may improve vasodilation, reduce thrombosis, and inhibit progression of atherosclerosis and provides a pathophysiological basis for the beneficial effects of aspirin in atherosclerosis.

Long-term prognosis in unstable angina. The importance of early risk stratification using continuous ST segment monitoring

AIMS

To assess the ability of clinical characteristics, admission ECG and continuous ST segment monitoring in determining long-term prognosis in unstable angina.

METHODS

Two hundred and twelve patients with unstable angina (mean age 59 years), presenting within 24 h of an acute episode of angina were recruited at three hospitals and treated with standardized medical therapy. All patients kept chest pain charts and underwent ST segment monitoring for 48 h. The occurrence of death, myocardial infarction, and need for revascularization was assessed over a median follow-up of 2.6 years.

RESULTS

The risk of death of myocardial infarction was greatest in the first 6-8 weeks after admission. Admission ECG ST depression and the presence of transient ischaemia predicted increased risk of subsequent death or myocardial infarction, whereas a normal ECG predicted a good prognosis. In 14 patients, ST segment monitoring provided the only evidence of recurrent ischaemia, and 72% of this group suffered an adverse event. Transient ischaemia and a history of hypertension were the most powerful independent predictors of death or myocardial infarction.

CONCLUSIONS

Adverse events in unstable angina occur early after admission and can be predicted by clinical and ECG characteristics, and by the presence of transient ischaemia during ST segment monitoring. Risk stratification by these simple assessments can identify patients with unstable angina at high risk.

Blood pressure changes during transient myocardial ischemia: insights into mechanisms

OBJECTIVES

We investigated the contribution of changes in systemic blood pressure to the genesis of spontaneous myocardial ischemia.

BACKGROUND

Although increases in heart rate often precede the development of spontaneous myocardial ischemia, it remains a subject of controversy whether these are accompanied by simultaneous changes in blood pressure.

METHODS

Using an ambulatory monitoring device that triggered blood pressure recordings from the level of the ST segment, we documented systolic and diastolic blood pressure and heart rate changes related to episodes of ST segment depression in 17 patients with stable coronary artery disease.

RESULTS

Systolic blood pressure and heart rate, but not diastolic pressure, increased significantly before the onset of ST segment depression and persisted throughout the ischemic episode. There was a significant correlation between the changes in heart rate and systolic blood pressure during episodes of myocardial ischemia (r = 0.5, p = 0.0005) and between heart rate and systolic blood pressure changes at 1-mm ST segment depression during treadmill exercise testing and ambulatory monitoring (r = 0.73, p = 0.0005 for heart rate; r = 0.77, p = 0.0008 for systolic blood pressure), indicating that patients with a low heart rate threshold during ischemic episodes also had a lower systolic blood pressure threshold before ischemia during both tests. Circadian changes in systolic blood pressure paralleled the variations in heart rate and ischemic episodes, with the lowest values at night.

CONCLUSIONS

Significant increases in myocardial oxygen demand, including systolic blood pressure, occur during episodes of spontaneous myocardial ischemia. Patients with a lower heart rate threshold during ischemic episodes had a lower systolic blood pressure threshold during both ambulatory monitoring and treadmill exercise. The effects of antianginal therapy on blood pressure changes during ischemia need to be explored further.

Informed consent from whom?

To obtain legally safe informed consent requires that the patient has a 'substantial understanding' of the proposed procedure and that the doctor obtaining the informed consent has sufficient knowledge to explain the nature of the procedure to the patient. In this paper we have shown that significant misunderstanding exists among non-specialist junior doctors of certain common orthopaedic procedures and conditions. Junior doctors often lack sufficient technical training to fully inform their patients and thus meet legal requirements. The implications of this are that the onus falls even more on specialists to ensure that their patients receive a more detailed explanation of the proposed intervention.

Pathophysiology of transient myocardial ischemia in acute coronary syndromes. Characterization by continuous ST-segment monitoring

BACKGROUND

Transient ischemia in stable coronary disease peaks in the morning, reflecting increased myocardial oxygen demand and coronary vasomotor tone after walking. In acute coronary syndromes, however, ischemia may result from transient thrombus formation or coronary spasm at the site of a ruptured plaque. We report on the pathophysiological mechanisms underlying transient ischemia in acute coronary syndromes despite optimal therapy, on the basis of analysis of heart rate changes preceding ischemia and its circadian variation.

METHODS AND RESULTS

Two hundred fifty-six patients with unstable angina or non-Q-wave myocardial infarction underwent continuous ST-segment monitoring for 48 hours while receiving maximal medical therapy. All ischemic episodes were characterized by their timing, duration, association with pain, and heart rate changes before the onset of ischemia. During 10,629 hours of monitoring, 44 patients (17.2%) had 176 episodes of transient ischemia. The mean heart rate at onset of ischemia was 68 +/- 12.8 bpm, and > 55% of ischemic episodes were not preceded by a significant increase in heart rate. Ischemic activity had a single nocturnal peak, with 64% of all episodes occurring between 10 PM and 8 AM, this nocturnal preponderance being evident for episodes with or without a preceding increase in heart rate. The characteristics and timing of transient ischemia were similar in unstable angina and non-Q-wave myocardial infarction, but transient ischemia was more frequent (27.3% versus 15.1%; P < .05) and prolonged (median, 20 versus 13.5 minutes; P < .01) in non-Q-wave myocardial infarction.

CONCLUSIONS

In acute coronary syndromes, transient ischemia has a low threshold, occurs predominantly without an increase in myocardial oxygen demand, and is present mainly at night rather than in the morning. These findings in patients receiving maximal medical therapy suggest significant pathophysiological differences underlying transient ischemia compared with stable coronary disease.

Nitric oxide activity in the atherosclerotic human coronary circulation

OBJECTIVES

We determined the activity of nitric oxide at rest and after acetylcholine in the atherosclerotic human coronary circulation.

BACKGROUND

Although responses to acetylcholine, an endothelium-dependent vasodilator, are abnormal in patients with coronary atherosclerosis, whether this reflects abnormal nitric oxide activity in humans in vivo has not been investigated previously.

METHODS

We investigated the effects of intracoronary L-NG-monomethyl arginine (L-NMMA), a specific antagonist of nitric oxide synthesis, on coronary vascular resistance and epicardial coronary artery diameter at rest and after acetylcholine in 24 patients with coronary artery disease and in 12 subjects with angiographically normal coronary arteries who were free from atherosclerotic risk factors.

RESULTS

With L-NMMA, the 13 +/- 4% (mean +/- SEM) increase in coronary vascular resistance and the 4 +/- 1% lumen diameter narrowing in atherosclerotic patients were lower than the 38 +/- 9% increase in resistance and the 15 +/- 2% decrease in diameter (both p < 0.01) observed in normal control subjects, indicating reduced basal nitric oxide activity in atherosclerosis. The degree of angiographic atherosclerotic narrowing did not correlate with the magnitude of diameter reduction. Acetylcholine-induced coronary epicardial and microvascular dilation was also depressed in atherosclerotic patients (32.2 +/- 9% reduction in coronary vascular resistance with 10(-6) mol/liter acetylcholine) compared with normal control subjects (65.5 +/- 2% decrease, p < 0.01). L-NMMA inhibited acetylcholine-induced epicardial and microvascular vasodilation in both patient groups, but the inhibition was greater in normal control subjects than in atherosclerotic patients, indicating that stimulation of nitric oxide activity by acetylcholine is reduced in atherosclerotic patients compared with normal control subjects. Coronary vascular dilation with sodium nitroprusside was similar in both groups and was not suppressed by L-NMMA. Furthermore, L-arginine reversed the constrictor effects of L-NMMA, indicating that the action of L-NMMA is specifically caused by inhibition of nitric oxide production from L-arginine.

CONCLUSIONS

These findings indicate that 1) there is a reduced basal activity of nitric oxide in the human atherosclerotic epicardial and microvascular coronary circulation; and 2) acetylcholine-induced coronary vascular dilation is at least partly due to stimulation of the activity of nitric oxide, and the reduced response to acetylcholine is due to attenuation in the stimulated activity of nitric oxide in patients with atherosclerosis.

An evaluation of patients comprehension of orthopaedic terminology: implications for informed consent

We conducted a prospective study into patient comprehension of orthopaedic terminology that commonly appears on consent forms. The majority of patients questioned were unsure of the meaning of simple terms such as 'fracture reduction' or 'internal fixation'. All the patients questioned had signed consent forms recently for such procedures in an acute orthopaedic unit. We conclude that many patients willingly consent to procedures that they do not fully understand. This implies that there is an element of trust involved in the process of giving consent. We believe that this aspect of the doctor-patient relationship should be legally respected.

Ischemia during ambulatory monitoring as a prognostic indicator in patients with stable coronary artery disease

OBJECTIVE

To assess long-term prognostic significance of transient ischemia in patients with documented coronary artery disease and stable symptoms and to examine the relation between transient ischemia and the site of angiographic disease progression following acute cardiac events.

DESIGN

Cohort study with a mean+/-SD follow-up of 51.5+/-23.8 months.

SETTING

Ambulatory patients with stable coronary artery disease, assigned to medical therapy.

PATIENTS

A total 221 patients (173 men; mean age, 60.8 years) were recruited. Of the 221 patients, 101 (45.7%) had single-vessel, 86 (38.9%) had 2-vessel, and 34 (15.4%) had 3-vessel disease. A total of 135 had a positive exercise test for ischemia, and mean+/-SD resting left ventricular ejection fraction (LVEF) was 49.8%+/-11.4%. Using conventional criteria, patients were prospectively stratified as low risk for continued medical therapy (single-vessel disease, 2-vessel disease with negative exercise test, or LVEF> or =40%; n=189 [85.5%]) or high risk for continued medical therapy (multivessel disease with ischemia and/or left ventricular dysfunction; n=32 [14.5%]).

INTERVENTIONS

Ambulatory ST-segment monitoring, treadmill exercise testing, radionuclide ventriculography, and coronary angiography.

MAIN OUTCOME MEASURES

Demographic, clinical, ambulatory monitoring, treadmill exercise, and left ventricular function variables as independent predictors of acute (cardiac death, myocardial infarction, or unstable angina) or all (including revascularization) cardiac events in the overall and the low-risk population.

RESULTS

None of the clinical or noninvasive measures of ischemia were of prognostic significance in the overall or the low-risk group. The only significant independent predictor of outcome in all patients for all events, including revascularization, was the number of diseased vessels (X2=13.5 [df=1]; P<.001). Exclusion of vessel disease resulted in conventional risk stratification as the most significant predictor of outcome from all events in all patients (X2= 10.3 [df= 1]; P=.001). In the low-risk group, the number of diseased vessels was the only predictor for all events (X2=4.6; P=.03). For acute cardiac events, none of the variables tested were of prognostic significance. Based on the frequency of events in the low-risk patients, a 2-fold increase in the rate of cardiac events in patients with transient ischemia compared with those without transient ischemia during ambulatory monitoring could be excluded with greater than 85% power and alpha of .05. Of 30 patients suffering acute nonfatal cardiac events during follow-up, angiography was performed in 27, revealing significant progression of coronary disease in 24 (88.8%) and the development of new significant lesions at sites remote from previously significant lesions in 20 (74%) cases. These new lesions were equally likely to occur in those with or without transient ischemia at initial assessment.

CONCLUSIONS

Acute cardiac events in predominantly low-risk stable angina patients with confirmed coronary disease are unpredictable, and those more likely to suffer such an event cannot be identified by the detection of ambulatory ischemia. Acute nonfatal cardiac events result predominantly from the development of significant new coronary lesions, not initially severe enough to cause ischemia. Patients categorized as high risk for long-term medical therapy have an increased rate of cardiac events (mainly revascularization) when compared with low-risk patients.

Coronary vascular nitric oxide activity in hypertension and hypercholesterolemia. Comparison of acetylcholine and substance P

BACKGROUND

Whether the abnormal responses of the human coronary circulation to acetylcholine in patients with hypertension and hypercholesterolemia extend to other, nonmuscarinic stimulators of the endothelium and whether this signifies a specific abnormality of NO is not known.

METHODS AND RESULTS

We studied 26 patients with angiographically normal coronary arteries, 10 without risk factors, and 16 with either hypertension (n = 9) and/or hypercholesterolemia (n = 10). Dose-response curves were performed with acetylcholine, substance P, and sodium nitroprusside before and after NG-monomethyl-L-arginine (L-NMMA). Substance P produced predominantly epicardial coronary dilation, whereas the dilating effect of acetylcholine was mainly microvascular. There was no correlation between the responses to the two drugs. L-NMMA did not affect the response to sodium nitroprusside, but it suppressed dilation in response to both substance P and acetylcholine, suggesting that the latter promote bioavailability of NO from the coronary vascular endothelium. Compared with patients without risks, those with hypercholesterolemia and hypertension had significantly reduced vasodilation with substance P: 21% versus 12.6% (P = .004) increase in epicardial coronary diameter and 35% versus 19% (P < .05) decrease in vascular resistance. Similar differences were noted with acetylcholine but not with sodium nitroprusside or adenosine. Epicardial and microvascular dilations with substance P or acetylcholine after L-NMMA were similar in patients with and without risk factors, indicating that the reduced effect of endothelium-dependent vasodilators in those with hypertension and hypercholesterolemia is due to diminished NO activity.

CONCLUSIONS

(1) Substance P- and acetylcholine-induced coronary vasodilation, like that to acetylcholine, is at least partly due to stimulation of NO activity, indicating that the dysfunction of the coronary vascular endothelial cell layer is not restricted to muscarinic receptors. (2) Hypertension and hypercholesterolemia are associated with depression of both basal and pharmacologically stimulated bioavailability of NO.

Natural variability of transient myocardial ischaemia during daily life: an obstacle when assessing efficacy of anti-ischaemic agents?

OBJECTIVE

To assess the degree of variability of transient myocardial ischaemia during daily life in patients with coronary artery disease, which could confound the interpretation of trials of the therapeutic effects of anti-ischaemic agents.

DESIGN

Prospective method evaluation.

SETTING

Tertiary referral centre, outpatient clinic.

PATIENTS

Patients with stable angina, confirmed coronary artery disease, and a positive treadmill exercise test for ischaemia. Patients were not preselected on the basis of prior documented transient ischaemia during ambulatory ST segment monitoring.

INTERVENTIONS

A simulated drug-study with 4 monitoring phases in 16 subjects. To minimise variability in ischaemic activity, patients underwent weekly 48 hour ambulatory ST segment monitoring outside hospital off all prophylactic therapy on the same weekdays for 4 weeks.

MAIN OUTCOME MEASURE

Variability in the frequency and duration of transient myocardial ischaemia.

RESULTS

There was marked variability in both ischaemic activity and mean duration of ischaemia in patients with confirmed ischaemia, the greatest degree of variability being between patients and from day to day within weeks within patients, with a further contribution to variability being noted between fortnights within patients.

CONCLUSIONS

Despite assessment off all therapy and an adequate period of monitoring (48 hours) with small intervals between monitoring periods (5 days), marked variability in ischaemic activity was noted, and regression towards the mean was clearly shown. Ambulatory ST segment monitoring outside hospital is not a reliable method for assessing the therapeutic effects of anti-ischaemic agents.

Unreamed nailing of tibial fractures--a prospective study of the routine use of the unreamed tibial nail

We prospectively studied 44 patients treated with the AO Unreamed Tibial Nail (UTN) at two orthopaedic trauma units. There were 15 open fractures: eight type I, four type II, one type IIIA, and two IIIB (Gustilo). The mean follow-up time was 13 months (range 6-24 months). There were 14 type A, 26 type B and four type C fractures (AO classification, Muller). All patients with the open fractures had surgery within eight hours of injury. Closed fractures were treated on the next available trauma list. The mean time to fracture union was 15.3 weeks (range 10-26). In the closed fracture group (n = 29), the mean time to union was 14.9 weeks compared to 18.6 weeks for the open fracture group. There were no non-unions and no infections. One patient had a malunion and breakage of locking bolts occurred in two cases. Our results indicate that the UTN provides excellent results in the treatment of both closed and open fractures of the tibial shaft, with union times comparable to reamed techniques.

Women with chest pain: is exercise testing worthwhile?

OBJECTIVE

To determine the diagnostic value of the exercise tolerance test (ETT) in women presenting with chest pain.

DESIGN

Prospective study of all women presenting to a centre with chest pain between 1987 and 1993 who were assessed by an ETT and coronary angiography.

SETTING

The outpatient clinic of one consultant cardiologist in a tertiary referral centre.

PATIENTS

All women referred to this outpatient clinic with chest pain were screened. For inclusion, patients had to perform ETT and undergo coronary angiography. Of the 347 referred during this period, 142 were excluded because they were unable to perform ETT or because of Q waves or other abnormalities on their resting electrocardiogram.

RESULTS

Overall the sensitivity of the ETT was 68% and the specificity was 61%, with a positive predictive value of 0.61 and a negative predictive value of 0.68. There were 42 false positive and 31 false negative ETT results (36% of the study group). The predictive value of a negative test was higher in younger women (< 52 years) than in the older group (> or = 52 years) (P = 0.004), but the positive predictive value in the two groups was not significantly different. The predictive value of a negative test was also higher in those with two or fewer risk factors than in those with three or more risk factors (P = 0.001). The negative predictive value for those women above 52 years with three or more risk factors (24% of the study group) was only 0.25. Lack of chest pain during ETT was associated with a higher negative predictive value in the younger group than in the older women (P = 0.006).

CONCLUSIONS

In women with chest pain use of the ETT was a misleading predictor of the presence or absence of coronary disease in 36% of these patients. In particular, a negative test in older women with three or more risk factors had a very low predictive value. The inclusion of risk factors and division by age can, however, be used to identify a population at intermediate risk for coronary artery disease in whom the ETT result has the highest diagnostic utility.

Tenuous link between ischaemic threshold and both ambulatory ischaemia and symptom status over time in stable angina: a 5-year follow-up study

This study evaluates changes in ischaemic threshold over a 5-year period in patients with stable angina pectoris, who did not suffer any intervening cardiac event. Changes in ischaemic threshold are related to alterations in symptomatic status and ambulatory ischaemia. Over long-term follow-up, there is a significant fall in ischaemic threshold in such patients (mean heart rate at onset of ischaemia fell from 104 +/- 17.8 to 97 +/- 17.4 bpm: P < 0.001), but this is not matched by a worsening of either symptoms or ischaemia during daily life. In the 68% of patients that had a reduction in ischaemic threshold of > or = 5 bpm, 68% had either definite reduction or no change in symptoms and 84% had either reduction, abolition or no change in transient ischaemic activity. The dissociation between ischaemic threshold, ambulatory ischaemia and symptoms has implications for long-term monitoring and management of the patient with stable angina.

Patterns and behavior of transient myocardial ischemia in stable coronary disease are the same in both men and women: a comparative study

OBJECTIVES

This study sought to compare the circadian variations in transient ischemic activity, mean heart rate and ischemic threshold between women and men with coronary artery disease.

BACKGROUND

There is a circadian variation in ischemic activity, onset of myocardial infarction and sudden cardiac death in patients with coronary artery disease, but studies assessing ischemia have incorporated predominantly male subjects.

METHODS

Thirty-one women and 45 men underwent at least 48 h of ambulatory ST segment monitoring.

RESULTS

There was a similar and significant circadian variation in ischemic activity in both women and men (p < 0.0001 and p < 0.0001, respectively), with a trough at night, a surge in the morning and a peak between 1 and 2 PM, corresponding to a similar circadian variation in mean hourly heart rate (p < 0.0001) that was not different between men and women (p = 0.28, power to detect a shift 99.9%). Mean heart rate at onset of ischemia (ischemic threshold) had similar variability in women and men (p = 0.96), and harmonic regression analysis confirmed a significant circadian variation (p < 0.0001), with a trough at night and a peak during activity hours. Heart rate increased significantly in the 5 min before ischemia throughout the 24 h (p < 0.0001), with no gender differences in the pattern of preonset to onset heart rate changes over time (p = 0.52); the smallest differences were recorded in the middle of the night. The majority of ischemic episodes (80%) had a heart rate increase > 5 beats/min in the 5 min before ischemia, but there were no gender differences.

CONCLUSIONS

Women with coronary artery disease have a pattern of ischemic activity and underlying pathophysiologic mechanisms very similar to men. The importance of increase in myocardial oxygen demand in the genesis of ischemia in both men and women is reflected by similar magnitude of heart rate increases before ischemia. The lower ischemic threshold during the nocturnal hours, when blood pressure is also lower, is consistent with a circadian variation in underlying coronary vascular tone.

Sodium picosulphate compared with polyethylene glycol solution for large bowel lavage: a prospective randomised trial

Mechanical efficiency, patient acceptability and minimal biochemical perturbation are important factors in the choice of lavage solution for bowel preparation. This prospective randomised trial of 59 patients compared a polyethylene glycol bowel lavage solution (Klean Prep) to a sodium picosulphate solution (Picolax) considering their efficacy from both colonoscopists' and radiologists' points of view, patient acceptibility, and plasma biochemical changes. The sodium picosulphate solution was more acceptable to patients than the polyethylene glycol, and resulted in significantly less nausea and vomiting (p = 0.0025), and far fewer consumption difficulties (p < 0.0001). Mean plasma biochemical changes were significantly different for magnesium (p < 0.001), chloride (p < 0.01) and potassium (p < 0.02). Because neither lavage solution displayed a marked advantage for the colonoscopist or radiologist, and sodium picosulphate was more acceptable to patients, sodium picosulphate is the preferred solution for bowel preparation. The changes in plasma biochemistry values are unlikely to cause clinical problems.

Surgical correction of a simian foot

Congenital varus deformity of the first metatarsal can be secondary to the abnormal insertion of abductor hallucis, a space-occupying lesion of the first web space, or hypoplasia of the metatarsal. We report a unique case where all three factors were present in one foot. This was combined with talipes equinovarus, which gave the appearance of a simian or hand-like foot.

Early continuous ST segment monitoring in unstable angina: prognostic value additional to the clinical characteristics and the admission electrocardiogram

BACKGROUND AND OBJECTIVE

In unstable angina, clinical characteristics, resting electrocardiography, and early continuous ST segment monitoring have been individually reported to identify subgroups at increased risk of adverse outcome. It is not known, however, whether continuous ST monitoring provides additional prognostic information in such a setting.

DESIGN

Observational study of 212 patients with unstable angina without evidence of acute myocardial infarction admitted to district general hospitals, who had participated in a randomised study comparing heparin and aspirin treatment versus aspirin alone.

METHODS

Clinical variables and a 12 lead electrocardiogram (ECG) were recorded at admission, and treatment was standardised to include aspirin, atenolol, diltiazem, and intravenous glyceryl trinitrate, in addition to intravenous heparin (randomised treatment). Continuous ST segment monitoring was performed for 48 h and all inhospital adverse events were recorded.

RESULTS

The admission ECG was normal in 61 patients (29%), showed ST depression in 59 (28%) (17 > or = 0.1 mV), and T wave changes in a further 69 (33%). The remaining 23 had Q waves (18), right bundle branch block (four), or ST elevation (one). During 8963 h of continuous ST segment monitoring (mean 42.3 h/patient), 132 episodes of transient myocardial ischaemia (104 silent) were recorded in 32 patients (15%). Forty patients (19%) had an adverse event (cardiac deaths (n = 3), non-fatal myocardial infarction (n = 6) and, emergency revascularisation (n = 31)). Both admission ECG ST depression (P = 0.02), and transient ischaemia (P < 0.001) predicted an increased risk of non-fatal myocardial infarction or death, while no patients with a normal ECG died or had a myocardial infarction. Adverse outcome was predicted by admission ECG ST depression (regardless of severity) (odds ratio (OR) 3.41) (P < 0.001), and maintenance beta blocker treatment (OR 2.95) (P < 0.01). A normal ECG predicted a favourable outcome (OR 0.38) (P = 0.04), while T wave or other ECG changes were not predictive of outcome. Transient ischaemia was the strongest predictor of adverse prognosis (OR 4.61) (P < 0.001), retaining independent predictive value in multivariate analysis (OR 2.94) (P = 0.03), as did maintenance beta blocker treatment (OR 2.85) (P = 0.01) and admission ECG ST depression, which showed a trend towards independent predictive value (OR 2.11) (P = 0.076).

CONCLUSIONS

Patients with unstable angina and a normal admission ECG have a good prognosis, while ST segment depression predicts an adverse outcome. Transient myocardial ischaemia detected by continuous ST segment monitoring in such patients receiving optimal medical treatment provides prognostic information additional to that gleaned from the clinical characteristics or the admission ECG.

The Total Ischaemic Burden European Trial (TIBET). Effects of atenolol, nifedipine SR and their combination on the exercise test and the total ischaemic burden in 608 patients with stable angina. The TIBET Study Group

OBJECTIVES

To determine the effects of atenolol, nifedipine and their combination on exercise parameters and ambulatory ischaemic activity in patients with mild chronic stable angina.

SETTING

Multicentre, multinational study involving 608 patients from 69 centres in nine countries.

DESIGN

Placebo washout followed by double-blind parallel-group study comparing atenolol 50 mg bd, nifedipine SR 20 mg bd, and their combination. Patients underwent maximal exercise testing using either a bicycle (n = 289) or treadmill (n = 319) and 48 h of ambulatory ST segment monitoring outside the hospital environment at the end of the placebo washout period and after 6 weeks of active therapy.

RESULTS

Both medications alone and in combination caused significant improvements in exercise parameters and significant reductions in ischaemic activity during daily activities, when compared with placebo. There were, however, no significant differences between groups, for any of the measured ischaemic parameters although combination therapy resulted in a greater fall in resting systolic and diastolic blood pressure than either treatment alone.

CONCLUSIONS

In the management of mild chronic stable angina there appears to be little advantage gained from using combination therapy for ischaemia reduction.