Haptoglobin polymorphism, a genetic risk factor in coronary artery bypass surgery

Haptoglobin (Hp) 2-2 type has been associated with accumulation of atherosclerotic lesions in essential hypertension. The aim of this study was to investigate the relationship between Hp type and the extension of coronary lesions in 765 male patients who underwent coronary artery bypass grafting (CABG). In this group, relative Hp1 (0.418) and Hp2 (0.582) allele frequencies were comparable with those of the reference population. Candidate CABG patients with a Hp 2-2 type were overrepresented in the younger (< 45 years) age group (P < 0.05). Hp 2-2 patients needed more bypass grafts than Hp 1-1 patients (relative risk 1.92 95% C.I. 1.24-2.96). The Hp 2-2 type was overrepresented among victims of a previous acute myocardial infarction (P < 0.05) and among patients with a lower (< 45 years) age at infarction (P < 0.05). In patients who already underwent a previous CABG graft survival time was shortest in Hp 2-2 type (P < 0.05). Patients with a Hp 2-2 type more likely develop atherosclerotic lesions despite comparable serum lipid concentrations.

Distribution of lymphocyte subsets in bone marrow and peripheral blood is associated with haptoglobin type. Binding of haptoglobin to the B-cell lectin CD22

Haptoglobin is an acute phase protein showing a genetic polymorphism with 3 major types: Hp 1-1, Hp 2-1, and Hp 2-2. In this study, flow cytometric analysis demonstrated that all three haptoglobin types bind to CD22 on human B-lymphocytes with equal affinity. Comparison of reference values for lymphocyte subsets in peripheral blood and bone marrow showed significant differences between haptoglobin types. Haptoglobin 2-2 is associated with higher peripheral B-lymphocyte counts (P < 0.001) and CD4+ T-lymphocyte counts (P < 0.05). In bone marrow, CD4+ T-cell percentages were highest (P < 0.001) but B-cell percentages were lowest (P < 0.001) in haptoglobin 2-2 type. A negative correlation between serum haptoglobin 1-1 concentration and peripheral B-cell counts was observed (r = -0.663). Our results suggest that haptoglobin is involved in lymphocyte distribution. The present findings are a potential cause of over- or underestimation of lymphocyte subset counts in the clinical staging of immunodeficiency diseases.

Effect of nifedipine on superior mesenteric artery impedance in humans

OBJECTIVE

In a randomized, double-blind placebo-controlled study the acute effect of sublingual nifedipine (10 mg) on the superior mesenteric artery pulsatility index (p.i.) was studied over 60 min in 12 healthy subjects (Age 43 y).

METHODS

p.i. was considered as a parameter of vascular resistance and was calculated as the peak-to-peak amplitude of the waveform divided by the mean amplitude. p.i. measurements were performed with the subject resting and fasting and were made 5, 10, 15, 30, 45 and 60 min for 1 hour after nifedipine (10 mg) or placebo. Arterial blood pressure and heart rate were measured at the same times.

RESULTS

Placebo administration failed to change arterial blood pressure, heart rate or p.i. 5 min after 10 mg sublingual nifedipine, p.i. had significantly decreased from 5.0 to 3.8, with a nonsignificant decrease in arterial blood pressure and an increase in heart rate. By 15 min after nifedipine administration p.i. had further decreased to 3.1, and there was a concomitant significant decrease in mean arterial blood pressure and increase in heart rate. Sixty minutes after drug intake p.i. and arterial blood pressure were still below baseline not significant but the heart rate remained significantly increased.

CONCLUSION

Our data indicate that in healthy subjects sublingual administration of nifedipine had a vasodilator effect (decrease in p.i.) on the superior mesenteric vascular bed.

Impaired microcirculation in heart failure

The aim of the present study was to examine the nailfold capillary morphology and dynamics in treated chronic heart failure (CHF) in relation to parameters of left ventricular structure and function. Twenty patients with CHF class II according to the New York Heart Association underwent a capillaroscopic examination at the finger nailfold using a computerized videophotometric system (Capiflow) at rest and after 1 min arterial occlusion. Study parameters ere number, length and diameter of the capillaries as well as capillary blood velocity (CBV). Further experiments included echocardiography and determination of left ventricular ejection fraction by Tc scintigraphy. Nailfold capillaries in established CHF are enlarged and the CBV is dramatically decreased. The reactive hyperemic response to 1 min arterial occlusion is attenuated. CBV correlates positively with left ventricular ejection fraction (r = 0.61, p = 0.01) and inversely with left ventricular end-diastolic (r = -0.56, p = 0.04) and end-systolic (r = -0.69, p = 0.01) diameters. The time-to-peak flow after 1 min arterial occlusion is positively related (r = 0.68, p < 0.05) to the duration of CHF. Our data indicate that finger microcirculation in CHF deteriorates as a function of the severity and duration of heart failure.

Influence of central command and ergoreceptors on the splanchnic circulation during isometric exercise

The splanchnic circulation can make a major contribution to blood flow changes. However, the role of the splanchnic circulation in the reflex adjustments to the blood pressure increased during isometric exercise is not well documented. The central command and the muscle chemoreflex are the two major mechanisms involved in the blood pressure response to isometric exercise. This study aimed to examine the behaviour of the superior mesenteric artery during isometric handgrip (IHG) at 30% maximal voluntary contraction (MVC). The pulsatility index (PI) of the blood velocity waveform of the superior mesenteric artery was taken as the study parameter. A total of ten healthy subjects [mean age, 21.1 (SEM 0.3) years] performed an IHG at 30% MVC for 90 s. At 5 s prior to the end of the exercise, muscle circulation was arrested for 90 s to study the effect of the muscle chemoreflex (post exercise arterial occlusion, PEAO). The IHG at 30% MVC caused a decrease in superior mesenteric artery PI, from 4.84 (SEM 1.57) at control level to 3.90 (SEM 1.07) (P = 0.015). The PI further decreased to 3.17 (SEM 0.70) (P = 0.01) during PEAO. Our results indicated that ergoreceptors may be involved in the superior mesenteric artery vasodilatation during isometric exercise.

Renin-angiotensin-aldosterone system, RR-interval and blood pressure variability during postural changes after myocardial infarction

Low frequency (LF, 0.04-0.15 Hz) and high frequency (HF, 0.15-0.40 Hz) components of heart rate variability have been used to evaluate the autonomic nervous system. The sympathico-vagal balance as well as the renin-angiotensin-aldosterone (RAA) axis are disturbed in the post-acute phase of acute myocardial infarction (AMI). This study examined the relationship between the RAA-axis and spectral indices of the RR-interval and blood pressure (BP) variabilities during postural manoeuvres in the post-AMI period. Power spectral analysis of the RR-interval and BP variability was computed from non-invasive beat-to-beat BP measurements 10-12 days post-AMI, using Fast-Fourier transforms. Concomitantly, hormonal changes of the RAA-axis were determined and data were further correlated with the left ventricular ejection fraction. When the patient moved from the lying to the supine position all RAA-axis parameters significantly increased. Both LF and HF components of total RR-interval variability decreased upon standing, while the LF component of systolic and diastolic BP variability increased and HF components remained constant. In the upright position, plasma renin activity (P<0.01) and angiotensin II (borderline) were inversely related with the LF component of systolic BP. The aldosterone level was dissociated from plasma renin activity and angiotensin II. The left ventricular ejection fraction was inversely correlated (P<0.05) with systolic and diastolic BP variabilities and their LF and HF powers. These results suggest that the renin-angiotensin II system in the post-acute phase of AMI patients treated with aspirin and beta-blocking agents is correlated with cardiovascular autoregulation during postural manoeuvres.

Evaluation of transesophageal echocardiography as a diagnostic and therapeutic aid in a critical care setting

OBJECTIVES

To assess the impact of transesophageal echocardiography (TEE) on therapeutic management in relation to pulmonary artery catheterization (PAC) in the ICU.

DESIGN

Retrospective analysis of 108 consecutive TEE video and related patient files during a 7-month period.

SETTING

A 33-bed medical and surgical ICU.

METHODS

All critically ill patients with or without PAC in whom a TEE was performed, excluding postoperative cardiac surgical patients. Patients were divided in a cardiac and a septic group depending on the primary disease on admission to the ICU. The impact of TEE in relation to PAC on ICU management was evaluated in whether therapy changes were performed strictly on the basis of the TEE findings.

MAIN RESULTS

Of 64% of patients with a PAC, 44% underwent therapy changes after TEE: 41% in the cardiac and 54% in the septic subgroup. In 41% of patients without a PAC, TEE led to a change in therapy.

CONCLUSIONS

TEE results in altered therapeutic management in at least one third of our (noncardiac surgery) ICU patient population independent of the presence of a PAC.

Influence and interference of isosorbide dinitrate and food intake on superior mesenteric artery impedance in humans

The influence of isosorbide dinitrate (ISDN) and food ingestion on superior mesenteric artery impedance was investigated in 24 healthy volunteers (age 40 +/- 2.7 years). Superior mesenteric artery circulation was assessed by duplex ultrasound. Pulsatility index (PI) was considered as a parameter of vascular resistance and was calculated as the peak-to-peak amplitude of the waveform divided by the mean amplitude. The subjects were randomly allocated to four groups (ISDN, meal, ISDN + meal, meal + ISDN). PI measurements were performed in resting and fasting conditions and serially for 1 h after sublingual 5 mg ISDN, ingestion of a 300-kcal, 300-ml mixed liquid meal; sublingual 5 mg ISDN followed 10 min later by the test meal; and ingestion of the test meal followed 5 min later by sublingual 5 mg ISDN. Five minutes after 5 mg sublingual ISDN, PI had increased from 6.8 to 12.4, while after intake of a meal PI had decreased from 7.6 to 4.9. Separate effects of 5 mg ISDN and meal intake lasted for at least 1 h. The reflex vasoconstrictive effect of 5 mg ISDN on the superior mesenteric artery circulation was counterbalanced by ingestion of a meal in healthy volunteers.

Influence of drugs on blood pressure variability

AIM

To study the causes of blood pressure variability by using antihypertensive drugs.

METHODS

Survey of published studies.

RESULTS

The results are sometimes unclear and, for some drugs, contradictory. beta-Adrenoceptor antagonists appear to have no effect on blood pressure variability, whereas alpha-adrenoceptor antagonists and atropine can lessen the amplitude of the variations. Similarly, there is a decrease after the administration of clonidine. Guanfacine, however, which acts on the same central receptors, does not lessen variability. Calcium antagonists do not influence blood pressure variability and the results with angiotensin converting enzyme inhibitors are contradictory.

CONCLUSIONS

From these results we conclude that blood pressure variability is not dependent on beta-receptor activity or calcium-mediated mechanisms. It is most likely that both alpha-adrenergic tone and the vagal system have significant effects on blood pressure variability.

Antihypertensive effects of calcium antagonists. Clinical facts and modulating factors

There is no doubt that calcium antagonists are effective antihypertensive agents. Their antihypertensive potency is comparable with that of beta-blockers and angiotensin-converting enzyme inhibitors. Blood pressure decreases are dose dependent with no orthostatic reactions, and are more pronounced in patients with lower renin levels, which is demonstrable in both white and black patients; whether the blood pressure response is stronger in elderly patients remains to be ascertained. Blood pressure rises during stress are moderately decreased. Basic documentation has been obtained for first-generation calcium antagonists, and the newer members of this class of drugs--nearly all dihydropyridine derivatives--were developed to achieve greater vascular specificity and a longer duration of action. With calcium antagonists, blood pressure decreases are due to decreases in peripheral resistance. However, blood flow increases do not necessarily persist over time, thus raising the question of what is the mechanism for the long-term decreases in blood pressure. Several studies have shown that blood pressure variability is unchanged with calcium antagonists. However, blood pressure decreases are accompanied by regression of left ventricular hypertrophy, which is understandable in light of the strong correlation between parathyroid hormone and left ventricular hypertrophy. The use of calcium antagonists in the treatment of clinical hypertension can be guided by the following facts: 1) They are metabolically neutral and are accompanied by few or no life-threatening side effects that, when they do occur, tend to disappear over time; 2) They increase blood flow to muscle and help control angina pectoris as well as vasospastic diseases.

Cardiovascular responses elicited by different simulated diving manoeuvres

It has been documented that placing an ice-bag on the forehead causes similar cardiac and vascular responses as face immersion. There has been disagreement concerning the contribution of separate cold stimulation on the face and breathholding in the diving response. This study set out to unravel the extent to which these two factors contribute individually to the observed cardiovascular changes during the combined manoeuvre. It further aimed to reveal whether peripheral vascular responses to these stimuli are different in forearm and calf. We observed a significant rapid increase in the RR-interval, which was maintained until the end of the 25-s observation period and a homogeneous vasoconstriction in forearm and calf, despite minor changes in arterial blood pressure, during breathholding, placing the icebag on the forehead and the combined stimuli. Cardiac and peripheral vascular responses to the combined manoeuvre did not differ significantly from the responses elicited by the two stimuli separately. This test is another example that illustrates the heterogeneous cardiovascular response involving both parasympathetic and sympathetic activation. Moreover, since the icebag on the forehead test is technically easy to perform and does not require the active co-operation of the patient, it may be a valid method to replace a full face immersion test accompanied by breathholding.

Age-related differences in presentation, treatment and outcome of acute myocardial infarction

Recent information on differences in presentation, evolution, therapy and outcome of myocardial infarction (MI) between age groups consists mainly of the result of clinical trials, evaluating highly selected patients and can therefore be difficult to extrapolate. We studied age-related differences in 167 consecutive typical cases, admitted in our hospital. Twenty-nine percent of patients were > or = 75 years. With increasing age, the proportion with previous MI, old Q waves, absence of new Q waves, anterior or unknown site and bundle branch block rose. Atypical presentation was more common in patients > or = 75 years. Fewer patients of higher age groups received thrombolytics and beta-blockers. In-hospital mortality rose from 5% in the youngest to 33% in the highest age group, and was also related to the presence of old Q waves. Mortality after discharge, however, is more closely related to functional status at discharge.

Peripheral vascular changes and ambulatory blood pressure profiles

This study aimed to correlate blood pressure (BP) level assessed either by casual or by 24-h ambulatory BP monitoring and regional (calf and finger) blood flow and associated vascular resistance in subjects with low, intermediate, and high BP. In 75 subjects covering the range from low BP to normo- and hypertension, blood flow at calf and finger vessels were simultaneously measured using an ECG-triggered venous occlusion plethysmograph. Correlations were calculated between regional blood flow or vascular resistance and BP defined from casual and from 24-h ambulatory BP registrations, at rest, and after 3 min of arterial occlusion (reactive hyperemia). Correlations over the whole BP range, between calf and finger vascular resistances and BP, were highly significant both for casual (0.650 < r < 0.776) and for ambulatory (0.531 < r < 0.781) BP. The relations remained significant after adjustment for the age dependency of the blood pressure. At any BP level skin (finger) blood flow at rest and after arterial occlusion was higher than muscle (calf) blood flow. These data indicate that there is a progressive decrease in vasodilating capacity from low to high BP in both muscle and skin vessels. However, in the zone of borderline to moderate essential hypertensives, blood flow after 3 min arterial occlusion was already significantly decreased in the muscle circulation when compared to normotensives, while still maintained in the skin circulation.