Subendocardial ischemia after cardiopulmonary bypass

Research Progress and Clinical Value of Subendocardial Viability Ratio

Cardiovascular disease remains the leading cause of morbidity and mortality worldwide, with ischemic heart disease being a major contributor, either through coronary atherosclerotic plaque-related major vascular disease or coronary microvascular dysfunction. Obstruction of coronary blood flow impairs myocardial perfusion, which may lead to acute myocardial infarction in severe cases. The subendocardial viability ratio, also known as the Buckberg index, is a valuable tool for evaluation of myocardial perfusion because it reflects the balance between myocardial oxygen supply and oxygen demand. The subendocardial viability ratio can effectively evaluate the function of the coronary microcirculation and is associated with arterial stiffness. This ratio also has potential value in predicting adverse cardiovascular events and mortality in various populations. Moreover, the subendocardial viability ratio has demonstrated clinical significance in a range of diseases, including hypertension, aortic stenosis, peripheral arterial disease, chronic kidney disease, diabetes, and rheumatoid arthritis. This review summarizes the applications of the subendocardial viability ratio, its particular progress in the relevant research, and its clinical significance in cardiovascular diseases.

Comparison Between Invasive and Noninvasive Methods to Estimate Subendocardial Oxygen Supply and Demand Imbalance

Background

Estimation of the balance between subendocardial oxygen supply and demand could be a useful parameter to assess the risk of myocardial ischemia. Evaluation of the subendocardial viability ratio (SEVR, also known as Buckberg index) by invasive recording of left ventricular and aortic pressure curves represents a valid method to estimate the degree of myocardial perfusion relative to left ventricular workload. However, routine clinical use of this parameter requires its noninvasive estimation and the demonstration of its reliability.

Methods and Results

Arterial applanation tonometry allows a noninvasive estimation of SEVR as the ratio of the areas directly beneath the central aortic pressure curves obtained during diastole (myocardial oxygen supply) and during systole (myocardial oxygen demand). However, this “traditional” method does not account for the intra‐ventricular diastolic pressure and proper allocation to systole and diastole of left ventricular isometric contraction and relaxation, respectively, resulting in an overestimation of the SEVR values. These issues are considered in the novel method for SEVR assessment tested in this study. SEVR values estimated with carotid tonometry by "traditional” and "new” method were compared with those evaluated invasively by cardiac catheterization. The “traditional” method provided significantly higher SEVR values than the reference invasive SEVR: average of differences±SD= 44±11% (limits of agreement: 23% – 65%). The noninvasive “new” method showed a much better agreement with the invasive determination of SEVR: average of differences±SD= 0±8% (limits of agreement: ‐15% to 16%).

Conclusions

Carotid applanation tonometry provides valid noninvasive SEVR values only when all the main factors determining myocardial supply and demand flow are considered.

Impact of Short-Term Training Camp on Aortic Blood Pressure in Collegiate Endurance Runners

To investigate the influence of short-term vigorous endurance training on aortic blood pressure (BP), pulse wave analysis was performed in 36 highly trained elite collegiate endurance runners before and after a 7-day intense training camp. Subjects participated three training sessions per day, which mainly consisted of long distance running and sprint training to reach the daily target distance of 26 km. After the camp, they were divided into two groups based on whether the target training was achieved. Aortic systolic BP, pulse pressure, and tension-time index (TTI, a surrogate index of the myocardial oxygen demand) were significantly elevated after the camp in the accomplished group but not in the unaccomplished group, whereas the brachial BP remained unchanged in both groups. The average daily training distance was significantly correlated with the changes in aortic systolic BP (r = 0.608, p = 0.0002), pulse pressure (r = 0.415, p = 0.016), and TTI (r = 0.438, p = 0.011). These results suggest that aortic BP is affected by a short-term vigorous training camp even in highly trained elite endurance athletes presumably due to a greater training volume compared to usual.

Central diastolic pressure decay mediates the relationship between aortic stiffness and myocardial viability: potential implications for aortosclerosis-induced myocardial ischemia

OBJECTIVE

Stiffening of the aorta often precedes coronary events, but little is known about the aetiological mechanism. We hypothesized that the predisposition to myocardial ischemia could be attributable to aortosclerosis-induced alterations in the central haemodynamics during diastole.

METHODS

Using noninvasive tonometry and ultrasonography, we investigated the arterial pressure pulse waveforms, pulse wave velocities (PWVs) and compliance in 222 patients with hypertension. The diastolic pressure decay was quantified by fitting a mono-exponential curve as P(t) =  P0e [λ: decay index; P0: end-systolic pressure; t: time from end-systole]. The myocardial oxygen supply/demand balance was estimated from the subendocardial viability index (SVI).

RESULTS

The aortic pressure decay fit to an exponential curve significantly (R = 0.98 ± 0.02) and more closely than the radial pressure decay (P < 0.001). The aortic decay index (median, 0.59 s) was associated with the aortic PWV and compliance (but not with the peripheral PWV or resistance), even after controlling for age, sex, renal function, diabetes and hypercholesterolemia (P < 0.001). Also, both the aortic PWV and compliance (together with the augmentation index) were related to the SVI, although these relationships were no longer significant after accounting for the decay index. Mediation analysis revealed substantial mediating effects of the decay index on the relationship between aortic PWV or compliance and SVI (75-100%), despite the lack of similar effects of the augmentation index.

CONCLUSION

Aortic stiffening with reduced compliance potentially impairs myocardial viability by accelerating the diastolic exponential decay (rather than through enhancing late-systolic augmentation) of the central blood pressure, thus predisposing hypertensive patients to ischemic heart disease.

Chronic in Vivo Function of a New Ventricular Assist Device: The Extracorporeal Pulsatile Assist Device (Epad)

An extracorporeal pulsatile assist device (EPAD) is a valveless, single-chambered, pneumatically-actuated blood pump composed of a graft conduit, connecting ring, bladder, and blowmolded housing. This allows a simple and quick surgical procedure and is easily actuated with a conventional intraaortic balloon pumping console if desired. To evaluate in vivo pump functions, the EPAD was tested in calves as a left ventricular assist device for 6-24 days. The EPAD was well synchronized to the natural heart beat up to 130 bpm in the counterpulsation mode with mild systemic heparinization (active clotting time: 200-250 seconds). Heart rate, coronary flow and cardiac output were not significantly changed by on-off testing. However, the pump showed promising diastolic augmentation (10.8% increase in the diastolic pressure time index) in these chronic animal experiments.

Reduced Subendocardial Viability Ratio Is Associated With Unfavorable Cardiovascular Risk Profile in Women With Short Duration of Type 2 Diabetes

BACKGROUND

The pathophysiological perturbations underlying the unfavorable cardiovascular prognosis in women with type 2 diabetes (T2DM) remain elusive. Low subendocardial viability ratio (SEVR), an index of myocardial oxygen supply and demand, has been associated with intermediate cardiovascular risk markers and cardiovascular mortality in various populations. However, whether SEVR is associated with sex and cardiovascular risk markers in patients with T2DM remains to be clarified.

METHODS

We examined 86 T2DM patients (mean age 59±10 years, 47% women, median diabetes duration 1.9 (range 0.2-5.0) years) and 86 sex- and age-matched control subjects in a cross-sectional study. SEVR was noninvasively assessed by tonometry and markers of cardiovascular risk by carotid-femoral pulse wave velocity (PWV), homeostasis model assessment of insulin resistance (HOMA2-IR), C-reactive protein, urinary albumin/creatinine ratio, and heart rate variability.

RESULTS

Women with diabetes had significantly lower SEVR compared to both men with diabetes (161% ± 26% vs. 178% ± 32%, P < 0.01), women without diabetes (185% ± 24%, P < 0.001), and men without diabetes (188% ± 28%, P < 0.001). The differences remained significant after adjustment for age, systolic blood pressure, heart rate, diabetes, and smoking. SEVR was associated with PWV, HOMA2-IR, C-reactive protein, and reduced heart rate variability in patients and control subjects, but the associations became nonsignificant after adjustment for heart rate.

CONCLUSIONS

SEVR is reduced in women with short duration of T2DM and associated with cardiovascular risk markers. The latter association seems to be at least partly mediated via heart rate. We hypothesize that reduced SEVR may contribute to the unfavorable cardiovascular prognosis in women with diabetes.

Ventricular-vascular dynamics in pediatric patients with heart failure and preserved ejection fraction

OBJECTIVE

The details of the ventricular-vascular dynamics of heart failure with preserved ejection fraction (HFpEF) in children remain poorly understood. We tested the hypothesis that pediatric HFpEF patients have ventricular systolic, diastolic, and arterial stiffening at rest as well as impaired reserve function associated with coronary supply/demand imbalance.

METHODS

We studied the ventricular pressure-area relationship in 22 pediatric HFpEF patients and 22 control subjects before and after dobutamine infusion and during abdominal compression. Coronary supply/demand balance was assessed by subendocardial viability ratio (SEVR) calculated from the aortic pressure waveform.

RESULTS

Compared with controls, the HFpEF patients had significantly higher end-systolic (Ees) and arterial (Ea) elastance. Increased ventricular diastolic stiffness also occurred in the HFpEF patients, resulting in modest elevation of end-diastolic pressure (EDP) at rest (13.6±4.3 vs. 7.3±2.3mmHg, P<0.0001). The difference in EDP became more evident with a preload increase through abdominal compression, indicating a limited diastolic reserve in HFpEF patients (EDP changes; 11.3±6.2 for HFpEF vs. 3.4±0.6mmHg for controls, P=0.016). The HFpEF patients exhibited impaired beta-adrenergic reserve in ventricular contractility and ventricular-arterial coupling in response to dobutamine infusion. SEVR was significantly lower in the HFpEF (0.64±0.11) than in the control (0.79±0.07, P<0.0001) and was significantly correlated with LV diastolic stiffness and dobutamine-induced changes in ventricular contractility.

CONCLUSIONS

HFpEF in children involves higher ventricular-arterial stiffness at rest as well as impaired systolic and diastolic reserve, which closely correlate with impaired coronary supply/demand balance.

IABP: history-evolution-pathophysiology-indications: what we need to know

Treatment with the intraaortic balloon pump (IABP) is the most common form of mechanical support for the failing heart. Augmentation of diastolic pressure during balloon inflation contributes to the coronary circulation and the presystolic deflation of the balloon reduces the resistance to systolic output. Consequently, the myocardial work is reduced. The overall effect of the IABP therapy is an increase in the myocardial oxygen supply/demand ratio and thus in endocardial viability.

This is an overall synopsis of what we need to know regarding IABP. Furthermore, this review article attempts to systematically delineate the pathophysiology linked with the hemodynamic consequences of IABP therapy. The authors also look at the future of the use of the balloon pump and conclude that the positive multi-systemic hemodynamic regulation during IABP treatment should further justify its use.

Arterial stiffness of lifelong Japanese female pearl divers

Japanese female pearl divers called Ama specialize in free diving in the cold sea for collecting foods and pearls in oysters. Exercising in the water combined with marked bradycardia and pressor responses provides a circulatory challenge to properly buffer or cushion elevated cardiac pulsations. Because Ama perform repeated free dives throughout their lives, it is possible that they may have adapted similar arterial structure and function to those seen in diving mammals. We compared arterial stiffness of lifelong Japanese pearl divers with age-matched physically inactive adults living in the same fishing villages. A total of 115 Japanese female pearl divers were studied. Additionally, 50 physically inactive adults as well as 33 physically active adults (participating in community fitness programs) living in the same coastal villages were also studied. There were no differences in age (∼65 yr), body mass index, and brachial blood pressure between the groups. Measures of arterial stiffness, cardio-ankle vascular index and β-stiffness index were lower (P < 0.05) in pearl divers and physically active adults than in their physically inactive peers. Augmentation pressure and augmentation index adjusted for the heart rate of 75 beats/min were lower (P < 0.05) in pearl divers than in other groups. These results indicate that lifelong Japanese pearl divers demonstrate reduced arterial stiffness and arterial wave reflection compared with age-matched physically inactive peers living in the same fishing villages.

Guiding Hypertension Management Using Central Blood Pressure: Effect of Medication Withdrawal on Left Ventricular Function

BACKGROUND

Central blood pressure (BP) is an acknowledged contributor to end-organ damage and independent determinant of prognosis. Primary analysis from the BPGUIDE study demonstrated no detriment on left ventricular (LV) structure from central BP-guided hypertension management, despite significant medication withdrawal. However, the effect of this on LV function has not been investigated. In this study, we sought to investigate the impact of central BP-guided hypertension management on LV systolic and diastolic performance.

METHODS

A total of 286 enrollees with uncomplicated hypertension were randomized to therapeutic decisions guided by best-practice usual care (UC) or, in addition, by central BP intervention (CBP) for 12 months. Each participant underwent baseline and follow-up 2-dimensional echocardiography, with assessment undertaken by an expert blinded to participant allocation.

RESULTS

Antihypertensive medication quantity remained unchanged for UC but significantly decreased with intervention. However, no significant between-group differences were noted for changes during follow-up in both brachial and central BP, as well as other central hemodynamic parameters: augmentation index and augmented pressure. Similarly, there were no differences between groups in parameters of LV diastolic function: tissue e' velocity (∆UC vs. ∆CBP; P = 0.27) and E/e' ratio (∆UC vs. ∆CBP; P = 0.60), and systolic parameters: LV longitudinal strain (∆UC vs. ∆CBP; P = 0.55), circumferential strain (∆UC vs. ∆CBP; P = 0.79), and ejection fraction (∆UC vs. ∆CBP; P = 0.15).

CONCLUSIONS

Hypertension management guided by central BP, resulting in significant withdrawal of medication to maintain appropriate BP control, had no adverse effect on LV systolic or diastolic function. Clinical trials registration: Australia New Zealand Clinical Trial Registry Number ACTRN12608 000041358.

The effect of lower body weight support on arterial wave reflection in healthy adults

Body weight support (WS) during treadmill exercise is used to rehabilitate orthopedic/neurological patients. WS lowers musculoskeletal strain and load. It compresses the lower body and increases intrathoracic volume. We studied short-term effects of WS on wave reflection indices using applanation tonometry during progressive WS of 25%, 50%, and 75% of body weight in 25 healthy men. WS decreased mean heart rate from 79 to 69 beats/min (P < .001). Peripheral and central mean arterial, systolic, and pulse pressures (PP) remained unchanged. There was a trend toward lower peripheral and central diastolic pressure. PP amplification ratio decreased significantly (P = .005). Reflected wave characteristics: Augmented pressure and index increased in a stepwise manner with WS (both P < .001). Both ejection duration and systolic duration of the reflected pressure wave (Ätr) increased progressively (both P < .001). The round-trip travel time (Δtp) was unchanged. Left ventricular workload and oxygen demand: Left ventricular wasted pressure energy increased (P < .001), and the subendocardial viability ratio decreased (P = .005), whereas the tension time index remained unchanged. In normal men, WS acutely decreases the PP amplification ratio, increases the amplitude and duration of the reflected aortic pressure wave, and increases measures of wasted left ventricular pressure energy and oxygen demand.

Assessment of arterial stiffness for clinical and epidemiological studies: methodological considerations for validation and entry into the European Renal and Cardiovascular Medicine registry

Epidemiological studies have highlighted the role of arterial stiffness as a risk factor for development of cardiovascular (CV) diseases. Moreover, aortic stiffness has been shown to be a significant predictive factor of all-cause and CV mortality in different populations including patients with end-stage renal disease. Pulse-wave velocity (PWV) is the most widely used technique to assess arterial stiffness. Although PWV can be measured on any artery or between any arterial sites, only carotid-to-femoral PWV, representing stiffness of the aorta and iliofemoral axes, has been shown to have predictive value for morbidity and mortality. The several available commercial devices differ according to the type of signal (pressure, distension, flow) or by recording both sites simultaneously or using ECG synchronization. It is also possible to directly measure arterial diameter changes during the cardiac cycle and link them to local pulse-pressure changes, which provides the pressure-diameter relationship and stress-strain relationship if arterial wall thickness is also measured. These techniques are based on high-precision vascular echo tracking or magnetic resonance imaging and applanation tonometry. This paper summarizes the basic principles of arterial haemodynamics and various methodologies to assess stiffness and the latest consensus recommendations for clinical applications.

Changes in subendocardial viability ratio with acute high-altitude exposure and protective role of acetazolamide

High-altitude tourism is increasingly frequent, involving also subjects with manifest or subclinical coronary artery disease. Little is known, however, on the effects of altitude exposure on factors affecting coronary perfusion. The aim of our study was to assess myocardial oxygen supply/demand ratio in healthy subjects during acute exposure at high altitude and to evaluate the effect of acetazolamide on this parameter. Forty-four subjects (21 men, age range: 24-59 years) were randomized to double-blind acetazolamide 250 mg bid or placebo. Subendocardial viability ratio and oxygen supply/demand ratio were estimated on carotid artery by means of a validated PulsePen tonometer, at sea level, before and after treatment, and after acute and more prolonged exposure to high altitude (4559 m). On arrival at high altitude, subendocardial viability ratio was reduced in both placebo (from 1.63±0.15 to 1.18±0.17; P<0.001) and acetazolamide (from 1.68±0.25 to 1.35±0.18; P<0.001) groups. Subendocardial viability ratio returned to sea level values (1.65±0.24) after 3 days at high altitude under acetazolamide but remained lower than at sea level under placebo (1.42±0.22; P<0.005 versus baseline). At high altitude, oxygen supply/demand ratio fell both under placebo (from 29.6±4.0 to 17.3±3.0; P<0.001) and acetazolamide (from 32.1±7.0 to 22.3±4.6; P<0.001), its values remaining always higher (P<0.001) on acetazolamide. Administration of acetazolamide may, thus, antagonize the reduction in subendocardial oxygen supply triggered by exposure to hypobaric hypoxia. Further studies involving also subjects with known or subclinical coronary artery disease are needed to confirm a protective action of acetazolamide on myocardial viability under high-altitude exposure.

Augmentation index immediately after maximal exercise in patients with type 2 diabetes mellitus

INTRODUCTION

Patients with type 2 diabetes mellitus (T2DM) have exaggerated brachial and central (ascending aortic) blood pressure (BP) during exercise, which is associated with adverse outcomes. Central systolic loading, represented by the augmentation index (AIx), may contribute to exaggerated exercise central BP. This study sought to compare the central AIx response to peak exercise in T2DM and control patients and to identify mechanisms of altered exercise central AIx.

METHODS

Central BP and AIx were quantified by radial tonometry at rest and immediately after peak treadmill exercise in 106 patients with T2DM and 106 nondiabetic controls, pair-matched by age, gender, peak exercise brachial BP, and postexercise HR corresponding to tonometry acquisition. Cardiac volumes (by echocardiography) were assessed in a subgroup (22 T2DM and 22 controls) to derive rest and postexercise arterial-ventricular coupling parameters, including cardiac index (stroke volume index × HR), peripheral vascular resistance index (cardiac index / mean BP), and effective arterial elastance index (end-systolic pressure / stroke volume index). Reserve parameters (exercise--rest) were also defined.

RESULTS

Patients with T2DM had lower postexercise central AIx (-1% ± 13% vs 3% ± 14%, P = 0.038) and greater central AIx reserve (-24% ± 13% vs -20% ± 11%, P = 0.002) compared with controls, despite raised postexercise peripheral vascular resistance index (P = 0.013) and effective arterial elastance index (P = 0.011); these parameters independently predicted higher central AIx at rest (P < 0.01) but not after exercise. Moreover, T2DM was independently associated with lower postexercise central AIx (β = -0.21, P = 0.006). Cardiac index reserve, which was blunted in T2DM (P = 0.004), represented the only independent correlate of central AIx reserve (r = 0.39, P = 0.01).

CONCLUSIONS

Patients with T2DM have significantly (and paradoxically) lower postexercise central AIx and greater central AIx reserve, which may be explained by an impaired cardiac functional reserve.

Arterial stiffness and vascular complications in patients with type 1 diabetes: the Finnish Diabetic Nephropathy (FinnDiane) Study

INTRODUCTION/AIMS

While patients with type 1 diabetes (T1D) are known to suffer from early cardiovascular disease (CVD), we examined associations between arterial stiffness and diabetic complications in a large patient group with T1D.

METHODS

This study included 807 subjects (622 T1D and 185 healthy volunteers (age 40.6 ± 0.7 versus 41.6 ± 1.2 years; P = NS)). Arterial stiffness was measured by pulse wave analysis from each participant. Furthermore, information on diabetic retinopathy, nephropathy, and CVD was collected. The renal status was verified from at least two out of three urine collections.

RESULTS

Patients with T1D without signs of diabetic nephropathy had stiffer arteries measured as the augmentation index (AIx) than age-matched control subjects (17.3% ± 0.6% versus 10.0% ± 1.2%; P < 0.001). Moreover, AIx (OR 1.08; 95% CI 1.03-1.13; P = 0.002) was associated with diabetic laser-treated retinopathy in patients with normoalbuminuria in a multivariate logistic regression analysis. The same was true for AIx and diabetic nephropathy (1.04 (1.01-1.08); P = 0.004) as well as AIx and CVD (1.06 (1.00-1.12); P = 0.01) in patients with T1D.

CONCLUSIONS

Arterial stiffness was associated with microvascular and macrovascular complications in patients with T1D.

Arterial aging and arterial disease: interplay between central hemodynamics, cardiac work, and organ flow-implications for CKD and cardiovascular disease

Cardiovascular disease is an important cause of morbidity and mortality in patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD). All epidemiological studies have clearly shown that accelerated arterial and cardiac aging is characteristic of these populations. Arterial premature aging is heterogeneous. It principally involves the aorta and central capacitive arteries, and is characterized by preferential aortic stiffening and disappearance of stiffness/impedance gradients between the central and peripheral arteries. These changes have a double impact: on the heart, upstream, with left ventricular hypertrophy and decreased coronary perfusion; and, downstream, on renal and brain microcirculation (decrease in glomerular filtration and cognitive functions). Multifactorial at origin, the pathophysiology of aortic ‘progeria' and microvascular disorders in CKD/ESRD is not well understood and should be the focus of interest in future studies.

Cardiovascular autonomic neuropathy, HDL cholesterol, and smoking correlate with arterial stiffness markers determined 18 years later in type 1 diabetes

OBJECTIVE To examine the relationship between cardiovascular autonomic neuropathy and pulse waveform analysis (PWA) measures of arterial stiffness in a childhood-onset type 1 diabetes population. RESEARCH DESIGN AND METHODS Cardiac autonomic nerve function was measured in the baseline examination of the Pittsburgh Epidemiology of Diabetes Complications Study of childhood-onset type 1 diabetes by heart rate variability (R-R interval) during deep breathing and expressed as expiration-to-inspiration (E/I) ratio. Other cardiovascular and diabetes factors were also assessed. PWA was performed using SphgymoCor Px on 144 participants at the 18-year follow-up examination. Univariate and multivariate analyses for associations between baseline nerve function and other cardiovascular and diabetes-related factors were performed for augmentation index (AIx), augmentation pressure (AP), and subendocardial viability ratio (SEVR), a surrogate marker of myocardial perfusion. RESULTS E/I ratio correlated negatively with both AIx (r = -0.18, P = 0.03) and AP (r = -0.32, P < 0.001) and positively with SEVR (r = 0.47, P < 0.001) univariately. Lower baseline E/I ratio, HDL cholesterol, and a history of smoking were associated with higher follow-up (18 years later) AIx and AP and lower SEVR in multivariate analyses. Higher baseline HbA(1) was also associated with higher AP and lower SEVR multivariately. CONCLUSIONS Cardiovascular autonomic neuropathy is associated with increased arterial stiffness measures and decreased estimated myocardial perfusion in those with type 1 diabetes some 18 years later. This association persists after adjustment for potential confounders as well as for baseline HbA(1), HDL cholesterol, and smoking history, which were also associated with these PWA measures.

The effects of passive leg raising on arterial wave reflection in healthy adults

BACKGROUND

Passive leg raising (PLR) produces hemodynamic and physiological changes related to centralizing blood volume and baroreceptor activation.

METHODS/RESULTS

To evaluate the effects of PLR on central hemodynamics, we prospectively studied 50 healthy participants (80% male, age 37 +/- 12 years). Central aortic blood pressures (CA-BPs) and reflected wave properties were evaluated using applanation tonometry at baseline and upon 1 min of PLR. Heart rate (HR) was unchanged. Brachial artery (BA)-systolic BP, BA-diastolic BP, and BA-pulse pressure (PP) all decreased from baseline to PLR. Changes in BA-PP were significantly greater than changes in CA-PP. Reflected wave augmentation pressure (P(s)-P(i)), HR corrected augmentation index (AIx@75), and augmentation index decreased significantly [(P(s)-P(i)): 5 +/- 6 vs. 4 +/-5, P < 0.001; AIx@75%: 10 +/- 13 vs. 7 +/- 12, P = 0.004; AI%: 14 +/- 12 vs. 12 +/- 12, P = 0.014, respectively]. HR corrected ejection duration (ED(c)), round trip travel time (deltat(p)), and reflected wave systolic duration (deltat(r)) all increased upon PLR [ED(c): 433 +/- 15 vs. 444 +/- 17, P < 0.001; deltat(p): 149 +/- 18 vs. 156 +/- 20, P = 0.003; deltat(r): 174 +/- 33 vs. 179 +/- 32, P = 0.046, respectively]. Indices of left ventricular (LV) workload including wasted LV energy and tension-time index decreased upon PLR.

CONCLUSION

PLR decreases the amplitude and delays the onset of the reflected aortic pressure wave. This decreases wasted LV pressure energy and workload.

Surgical ventricular reconstruction with different myocardial protection strategies. A propensity matched analysis

The aim of this study is to compare outcomes of patients undergoing surgical ventricular reconstruction (SVR) with normothermic cardiopulmonary bypass (CPB) and beating heart or hypothermic CPB and cardioplegic arrest. Between 2001 and 2008, 588 patients underwent SVR. A propensity score matching was performed and 91 matched pairs were created: group 1 (G1) operated with normothermic CPB and beating-heart technique, and group 2 (G2) operated with hypothermic CPB and cardioplegic arrest. Mean age was 62+/-9 years in G1 and 63+/-10 years in G2 [not significant (NS)]. Average follow-up was 42.7+/-26 months (range 1-72). Major cardiac and cerebro-vascular events (MACCE) were assessed. Thirty-day mortality was 4% in G1 and 5% in G2 (NS). Kaplan-Meier survival at six years was 79+/-4% and 72+/-9% (NS) and freedom from MACCE was 82+/-4% and 83+/-7% in G1 and G2, respectively (NS). Left ventricular volume reduction, ejection fraction and New York Heart Association (NYHA) class improvement were significant in the overall population; no significant differences were found between groups. The following independent risk factors for cardiac death were identified: mitral valve regurgitation, surgery <3 months from myocardial infarction, NYHA class III-IV. This study showed that outcomes following SVR are not affected by myocardial protection strategies neither in cardiac function and clinical status nor in survival.

Morphological variants of acute myocardial necrosis and their relationship to coronary artery thrombosis

This communication describes the two chief morphological variants of acute myocardial necrosis and discusses the pathophysiological mechanisms underlying them. The frequency of occlusive thrombosis in anatomically related coronary arteries in acute regional infarction is stressed.

Surveillance of cardiovascular risk in the normotensive patient with repaired aortic coarctation

Background

Repaired coarctation of the aorta is associated with premature atherosclerosis and an increased risk of cardiovascular events even in normotensive subjects. To date clinical risk stratification has focused on brachial blood pressures ignoring the complex pulsatility of the aortic wave form. The aim of this study was to assess components of this pulsatility in a clinical setting and to suggest possible techniques to improve risk stratification.

Methods

This was a prospective study recruiting patients from a tertiary referral centre. Pulse wave morphology was assessed using applanation tonometry. B-mode ultrasound and cardiac magnetic resonance were used to assess carotid intimal–medial thickness and left ventricular mass.

Results

Forty-six subjects with repaired coarctation of the aorta (range 16–62 years; mean 31 years) and 20 matched controls were studied. Baseline brachial systolic and diastolic blood pressures were not statistically different between the 2 groups. Peripheral (62.5 mmHg (11.3) vs. 50.6 mmHg (15.0), p = 0.0008) and central (34.5 mmHg (7.7) vs. 28.7 mmHg (4.7), p = 0.005) pulse pressures were elevated in the coarctation patients compared to controls. The reflected pressure wave returned to the ascending aorta earlier in the coarctation group (p = 0.007) and the tension time index (TTI) was increased (p = 0.03). The sub-endocardial viability index (SVI) was reduced in the coarctation subjects (159 (33) vs. 186 (31)%; p = 0.009) but there was no differences in central augmentation index (p = 0.35).

Conclusions

This study demonstrates that there are patients with repaired coarctation who have an excellent mid-term outcome free from ventricular hypertrophy, carotid intima medial thickening and with relatively preserved vascular reactivity. However even in this “best outcome” cohort there were abnormal vascular characteristics that may predispose to increased cardiovascular risk. Simple non-invasive investigations can more extensively characterise these sub-clinical abnormalities and by utilised in long-term surveillance.

Arterioventricular Coupling and Ventricular Efficiency After Antihypertensive Therapy

Patients with hypertension exhibit impaired energetic coupling between the ventricle and the arterial system, leading to reduced cardiac mechanic efficiency and exercise capacity. We tested whether blood pressure normalization with current antihypertensive therapy can improve arterioventricular coupling. Eighteen hypertensive patients without other cardiovascular disease were examined before and after antihypertensive therapy. Transthoracic echocardiography was performed. Central aortic pressure waveforms, including end-systolic pressure, were derived from radial artery applanation tonometry. Afterload was increased with isometric handgrip exercise. Central aortic end-systolic pressure and ventricular volumes at rest and handgrip were used to calculate ventricular elastance, effective arterial elastance, arterioventricular coupling (effective arterial elastance/ventricular elastance), and mechanical efficiency. After 142±67 days, systolic blood pressure decreased from 150.9±14.6 to 119.8±9.2 mm Hg ( P <0.00001), diastolic blood pressure from 85.9±14.8 to 68.8±8.4 mm Hg ( P =0.00002), and cardiac output from 5.8±1.7 to 4.9±1.8 L/min ( P =0.03). Resting left ventricular end-systolic volume, ejection fraction, and septal thickness did not change. Ventricular elastance increased from 1.7±1.0 to 3.2±1.4 mm Hg/mL ( P =0.00002), whereas effective arterial elastance decreased from 1.4±0.5 to 1.2±0.4 mm Hg/mL ( P =0.02). Effective arterial elastance/ventricular elastance decreased in all patients, from 1.1±0.8 to 0.4±0.2 ( P =0.0002). Efficiency improved at rest (72.9±5.8% versus 83.5±5.7%; P <0.00001) and during handgrip (63.5±7.8% versus 78.9±7.1%; P <0.00001). In hypertensive patients, optimal brachial and central blood pressure reduction shifts arterioventricular coupling from cardiac output maximization to ventricular mechanical efficiency optimization. This occurs before significant changes in ventricular geometry and may be responsible for early clinical improvements.

Reduced aortic distensibility and coronary flow velocity reserve in diabetes mellitus patients with a negative coronary angiogram

BACKGROUND

Structural and functional abnormalities of the aortic wall and disturbances of the coronary circulation with presumed microvascular complications have been reported in patients with diabetes mellitus.

OBJECTIVES

To simultaneously establish the coronary flow velocity reserve (CFVR) and aortic distensibility indexes in type 2 diabetes mellitus patients who have normal epicardial coronary arteries by stress transesophageal echocardiography (STEE).

METHODS

The elastic properties of the descending aorta and the CFVR were evaluated simultaneously in 18 type 2 diabetes mellitus patients who had negative coronary angiograms. These results were compared with those of 21 nondiabetic subjects with normal epicardial coronary arteries and 24 patients with left anterior descending coronary artery (LAD) stenosis. STEE was used for the evaluation of elastic moduli of the descending aorta. The CFVR was calculated as the ratio of the average peak diastolic flow velocity during hyperemia to that at rest.

RESULTS

The CFVR of diabetic patients with normal epicardial coronary arteries and those with LAD stenosis was similarly decreased compared with the controls (2.10+/-0.63 and 1.78+/-0.47 versus 2.76+/-1.25, P<0.05 and P<0.001, respectively). The elastic modulus (in 103 mmHg) was similarly increased in patients with diabetes mellitus and normal epicardial coronary arteries, and in those with LAD stenosis, compared with the control subjects (0.94+/-0.82 and 0.91+/-0.59 versus 0.49+/-0.19, P<0.05 and P<0.05, respectively).

CONCLUSIONS

It may be stated that reduced aortic distensibility (increased elastic modulus) and the CFVR were demonstrated simultaneously during STEE in diabetic patients compared with nondiabetic subjects with negative coronary angiograms.

Diastolic blood pressure and mortality in the elderly with cardiovascular disease

Isolated systolic hypertension is predominantly observed in the elderly because of increased arterial stiffness. Aggressive treatment leads to excessive lowering of diastolic blood pressure and favors the presence of a J-shaped curve association with mortality. We investigated whether, in the elderly, this pattern of association is a simple epiphenomenon of increased arterial stiffness and impaired cardiac function. In a cohort of 331 hospitalized subjects >70 years old (mean age+/-SD: 85+/-7 years), aortic pulse wave velocity and pressure wave reflections, by pulse wave analysis, and cardiac function, by ultrasound, were assessed. During a 2-year follow-up period, 110 subjects died. No association of prognosis with systolic pressure, pulse pressure, or pulse wave velocity was observed. A J-shaped association between diastolic pressure and overall and cardiovascular mortality was observed. Unadjusted Cox regression analysis showed that patients in the first tertile of diastolic pressure (< or =60 mm Hg) had higher mortality. In Cox regression analysis, diastolic pressure < or =60 mm Hg was a predictor of mortality independently from cardiac-vascular properties, cardiovascular risk factors, and drug treatment. Multivariate regression analysis showed that increased age and low total peripheral resistance, but not left ventricular function, were the cardinal determinants of low diastolic pressure. An "optimal" diastolic pressure of 70 mm Hg in subjects with isolated systolic hypertension was found. We showed that, in the frail elderly, a value of diastolic blood pressure < or =60 mm Hg is associated with reduced survival, independent from large artery stiffness and left ventricular function, suggesting that more rational antihypertensive therapy, not only based on systolic pressure level, is needed.

Amphetamine increases blood pressure and heart rate but has no effect on motor recovery or cerebral haemodynamics in ischaemic stroke: a randomized controlled trial (ISRCTN 36285333)

Amphetamine enhances recovery after experimental ischaemia and has shown promise in small clinical trials when combined with motor or sensory stimulation. Amphetamine, a sympathomimetic, might have haemodynamic effects in stroke patients, although limited data have been published. Subjects were recruited 3-30 days post-ischaemic stroke into a phase II randomized (1:1), double-blind, placebo-controlled trial. Subjects received dexamphetamine (5 mg initially, then 10 mg for 10 subsequent doses with 3- or 4-day separations) or placebo in addition to inpatient physiotherapy. Recovery was assessed by motor scales (Fugl-Meyer (FM)), and functional scales (Barthel index (BI) and modified Rankin score (mRS)). Peripheral blood pressure (BP), central haemodynamics and middle cerebral artery blood flow velocity were assessed before, and 90 min after, the first two doses. Thirty-three subjects were recruited, aged 33-88 (mean 71) years, males 52%, 4-30 (median 15) days post stroke to inclusion. Sixteen patients were randomized to placebo and seventeen to amphetamine. Amphetamine did not improve motor function at 90 days; mean (s.d.) FM 37.6 (27.6) vs control 35.2 (27.8) (P=0.81). Functional outcome (BI, mRS) did not differ between treatment groups. Peripheral and central systolic BP, and heart rate (HR), were 11.2 mm Hg (P=0.03), 9.5 mm Hg (P=0.04) and 7 beats per minute (P=0.02) higher, respectively, with amphetamine, compared with control. A nonsignificant reduction in myocardial perfusion (BUI) was seen with amphetamine. Other cardiac and cerebral haemodynamics were unaffected. Amphetamine did not improve motor impairment or function after ischaemic stroke but did significantly increase BP and HR without altering cerebral haemodynamics.

Two-week treatment with pravastatin improves ventriculo-vascular haemodynamic interactions in young men with type 1 diabetes

Young patients with diabetes but without established vascular disease have altered conduit and resistance artery reactivity. Early endothelial dysfunction is an initial step in atherogenesis: reductions in nitric oxide (NO) production in these vascular beds are implicated. The study aim was two-fold: first, to detect baseline abnormalities in cardiac function, conduit vessels and the microcirculation using applanation tonometry, brachial artery ultrasound and laser Doppler fluximetry, respectively; and second, to investigate any modification in these parameters with the use of pravastatin. Nine young men with diabetes and normoalbuminuria were randomised in a double-blind cross-over fashion to placebo or pravastatin (40 mg) treatment for two weeks. They underwent scans on three separate occasions. Control patients (n=12) underwent a baseline scan but were not given any drug treatment. It was found that patients with diabetes had significantly higher systolic and diastolic blood pressures, heart rate and Buckberg index (propensity to myocardial ischaemia). Brachial artery reactivity and microcirculatory dilation were both reduced. Levels of von Willebrand Factor, a marker of endothelial damage, were also elevated. Pravastatin treatment restored these sub-clinical abnormalities towards normal levels. In conclusion, pravastatin improves vascular abnormalities in young male patients with diabetes through alterations in microcirculation and conduit vessel function, with secondary myocardial effects. This may be of benefit in preventing end-organ injury.

Rationale, design and baseline data of a randomized, double-blind, controlled trial comparing two antithrombotic regimens (a fixed-dose combination of extended-release dipyridamole plus ASA with clopidogrel) and telmisartan versus placebo in patients with strokes: the Prevention Regimen for Effectively Avoiding Second Strokes Trial (PRoFESS)

BACKGROUND

Individuals with transient ischemic attack and ischemic stroke have a high risk of recurrent stroke and death. While acetylsalicylic acid (ASA, aspirin) is proven and accepted as standard therapy in these patients, recent trials demonstrate that a combination of ASA and dipyridamole (DP) or clopidogrel may be superior to ASA. Blocking the renin-angiotensin system with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers may also reduce recurrent stroke. The ongoing PRoFESS (Prevention Regimen for Effectively Avoiding Second Strokes) trial is designed to evaluate whether ASA + extended-release DP compared to clopidogrel, and whether telmisartan in addition to usual care in individuals after a stroke, will reduce the risk of further strokes.

METHODS

PRoFESS is a multicenter, randomized, double-blind trial involving 695 sites from 35 countries or regions. Patients > or = 50 years presenting with an ischemic stroke < 120 days who were stable were randomized. The primary outcome for the trial is recurrent stroke, using a time-to-event analysis. The most important secondary outcome is the composite of stroke, myocardial infarction or vascular death. Other secondary outcomes include this composite + congestive heart failure, new-onset diabetes, other designated occlusive vascular events (pulmonary embolism, deep-vein thrombosis, peripheral arterial occlusion, transient ischemic attack, cerebral venous thrombosis or retinal vascular accident not classified as stroke), any death, stroke subtype by TOAST criteria and Mini Mental State Examination score. Safety is evaluated by assessing the risk of major hemorrhagic events. The comparison between ASA + DP and clopidogrel is based on an initial assessment of noninferiority, followed by evaluation of superiority, while for telmisartan, we will assess its superiority over placebo.

RESULTS

With over 20,000 patients randomized, and utilizing a 2 x 2 factorial design, PRoFESS is the largest stroke trial to investigate the prevention of recurrent stroke. The mean age was 66.1 +/- 8.6 years, and 36.0% of the patients were females. The median time from qualifying event to randomization was 15 days with 39.9% of patients randomized within 10 days. According to the TOAST criteria, 28.5% of the strokes were due to large-vessel disease, 52.1% to small-vessel disease, 1.8% to cardioembolism, and 2.0% to other determined etiologies and 15.5% were of undetermined etiology.

CONCLUSIONS

PRoFESS is the largest secondary stroke prevention trial to date and will directly compare two antiplatelet regimens as well as the benefit of telmisartan versus placebo.

Hyperthyroidism affects arterial stiffness, plasma NT-pro-B-type natriuretic peptide levels, and subendocardial perfusion in patients with Graves' disease

BACKGROUND

Arterial stiffness is thought to play a critical role in the pathogenesis of cardiovascular events, and in hyperthyroidism increased cardiovascular event rates have been reported.

AIM

To investigate markers of systemic arterial stiffness, volume homeostasis, and subendocardial perfusion and its interrelationship in patients with Graves' disease (GD) in hyperthyroidism and euthyroidism.

METHOD

Aortic augmentation index (AIx@75) as a measure of systemic arterial stiffness and subendocardial viability ratio (SEVR) as a surrogate measure of subendocardial perfusion were assessed by applanation tonometry in 59 patients with GD in hyperthyroidism and euthyroidism, and measurements were compared to plasma levels of NT-pro-B-type natriuretic peptide (NT-ProBNP).

RESULTS

AIx@75 and NT-ProBNP levels were significantly increased in hyperthyroidism compared to euthyroidism and were positively correlated with each other. SEVR was significantly decreased in hyperthyroidism compared to euthyroidism, mainly due to increased heart rates as shown by the heart rate-corrected SEVR75.

CONCLUSIONS

In hyperthyroidism, patients with GD exhibited increased systemic arterial stiffness, paralleled by increased levels of NT-ProBNP, a marker of volume overload. The decreased subendocardial perfusion in hyperthyroidism seemed to be mainly due to increased heart rates. The observed unfavorable hemodynamic alterations in hyperthyroidism may serve to explain increased cardiovascular event rates in patients with GD.

Cardiovascular disease in the dialysis population: prognostic significance of arterial disorders

PURPOSE OF REVIEW

Cardiovascular disease is a major factor in the high mortality of patients with end-stage renal disease, and this population is particularly appropriate to analyse the impact of cardiovascular risk markers on outcome.

RECENT FINDINGS

Cardiovascular risk markers in end-stage renal disease include age, left ventricular mass, carotid intima-media thickness, blood pressure and aortic stiffness (pulse wave velocity). Aortic pulse wave velocity has been shown to be an independent predictor of cardiovascular mortality in patients with end-stage renal disease and the general population. Aortic pulse wave velocity has the highest sensitivity and specificity as a predictor of cardiovascular death in end-stage renal disease patients. Pulse wave velocity is an integrated index of vascular function and structure, and is a major determinant of systolic hypertension, thereby increasing left ventricular afterload, left ventricular hypertrophy and left ventricular oxygen consumption. Decreased diastolic blood pressure, another consequence of arterial stiffening, is associated with decreased coronary perfusion contributing to ischaemic heart disease and evolution of adaptive into maladaptive left ventricular hypertrophy.

SUMMARY

Aortic stiffness measurements could serve as an important tool in identifying end-stage renal disease patients at higher risk of cardiovascular disease. The ability to identify these patients would lead to better risk stratification and earlier and more cost-effective preventive therapy.

Impact of Treatment With Protease Inhibitors on Aortic Stiffness in Adult Patients With Human Immunodeficiency Virus Infection

Background— The role of antiretroviral therapy in acceleration of atherosclerosis in patients with human immunodeficiency virus (HIV) infection is controversial. We hypothesized that aortic stiffness, an early marker of arteriosclerosis, may be increased in HIV patients treated with protease inhibitors.

Methods and Results— In 32 HIV-infected patients treated with protease inhibitors and 32 age-, sex-, and blood pressure–matched HIV-uninfected control subjects, we obtained aortic pulse wave velocity and central aortic pressure waveform, from which aortic augmentation was calculated. HIV patients had a higher aortic pulse wave velocity (7.6±1.1 versus 6.8±1.2 m×s −1 , P =0.015) and aortic augmentation (6.8±5 versus 4.6±4 mm Hg, P =0.037) than control subjects. Age and HIV infection (both P <0.05) independently predicted aortic pulse wave velocity when a consistent number of cardiovascular risk factors was simultaneously controlled for. The cumulative duration of treatment was a predictor of aortic pulse wave velocity, each 5 years of treatment duration being independently related to a 1.35 m×s −1 increase in pulse wave velocity.

Conclusions— Aortic stiffness is increased in HIV-positive individuals receiving antiretroviral therapy including a protease inhibitor. Pulse wave velocity increases with longer exposure to protease inhibitors. We hypothesize that arteriosclerosis is a side effect of antiretroviral treatment including a protease inhibitor.

Cardiovascular responses to short-term head-down positioning in healthy young and older adults

BACKGROUND AND PURPOSE

Isolated head-down postural drainage is assumed to acutely load the cardiovascular system. Consequently, it is considered a relative contraindication in the presence of severe cardiovascular disease. Evidence demonstrating that the head-down manoeuvre as used by physiotherapists does significantly load the cardiovascular system is lacking. The present study documents the cardiovascular responses t short-term 30 degrees head-down positioning in healthy subjects. The results are a point of reference for respiratory patients with and without cardiovascular disease.

METHOD

A quasi-experimental research design was used, with multiple measurements obtained at rest (long sitting and in the head-down position. Twenty-one young subjects (mean age 25 years (standard deviation, (SD) 3 years)) and 19 older subjects (mean age 66 years (SD 6 years)) were studied. Applanation tonometry and sphygmocardiography were used to measure temporal and pressure variables, and indices that estimate myocardial work and coronary blood flow.

RESULTS

Absolute differences existed between the two age groups for all variables at rest (p < 0.001). No age-time interaction was observed for any variable in the head-down position (p > 0.05). Serial measures in the head-down position did not vary across time (p > 0.05). Small (<9%) but significant (p < or = 0.02) decreases in heart rate, relative diastolic duration, mean arterial blood pressure and diastolic time indices, and small (<12%) but significant (p < or = 0.002) increases in cardiac cycle time, ejection duration (relative and absolute) and absolute diastolic duration were observed in the head-down position compared with rest. A small (9%) but significant (p < 0.001) fall in the sub-endocardial viability ratio occurred in the head down position.

CONCLUSION

The findings have little consequence in health, but they suggest that head-down postural drainage may be of concern for chest physiotherapy recipients with reduced cardiac reserve or impaired barorefilex function.

Arterial stiffness and function in end-stage renal disease

Cardiovascular disease is a major cause of mortality in patients with end-stage renal disease, with damage to arteries as a major contributing factor. Arterial stiffness is a factor associated with high systolic and pulse pressure in these patients and is a strong independent factor associated with morbidity and mortality. Arterial stiffness is one of the principal factors opposing left ventricular ejection. The appropriate term to define the arterial factor(s) opposing left ventricular ejection is aortic input impedance. Aortic input impedance depends on TPR, arterial distensibility, and wave reflections. Distensibility defines the capacitive properties of arterial stiffness, whose role it is to dampen pressure and flow oscillations and to transform pulsatile flow and pressure in arteries into a steady flow and pressure in peripheral tissues. Stiffness is the reciprocal value of distensibility. These parameters are blood pressure dependent; arteries become stiffer at high pressure. While distensibility provides information about the elasticity of the artery as a hollow structure, the elastic incremental modulus characterizes the properties of the arterial wall biomaterials independent of vessel geometry. Alternatively, arterial distensibility can be evaluated by measuring pulse wave velocity, which increases with the stiffening of arteries. Arterial stiffening increases left ventricular afterload and alters the coronary perfusion. With increased pulse wave velocity, the wave reflections affects the aorta during systole, which increases systolic pressures and myocardial oxygen consumption and decreases diastolic blood pressure and coronary flow. The arterial stiffness is altered primarily in association with increased collagen content and alterations of extracellular matrix and calcification of the arterial wall. The arterial stiffening estimated by changes in aortic pulse wave velocity and intensity of wave reflections are independent predictors of survival in end-stage renal disease and in the general population. Improvement of arterial stiffening could be obtained by antihypertensive treatments as observed with calcium-channel blockers and angiotensin-converting enzyme inhibitors. Angiotensin-converting enzymes inhibitors increase AC and reduce wave reflections. It has been shown that reversibility of aortic stiffening and use of angiotensin-converting enzyme inhibitors had a favorable independent effect on survival in hypertensive patients with advanced renal disease.

[Relationship between the subendocardial viability ratio and risk factors for ischemic heart disease]

Ischemic heart disease is one of the major causes of sudden death in Japanese workers. Hypercholesteremia, hypertension, obesity, and the smoking habit are considered to be risk factors for cardiovascular events. Generally the subendocardium is thought to be more sensitive to a shortage of blood supply than the subepicardium. Buckberg et al. have demonstrated that the ratio of the area of the diastolic phase (diastolic pressure time index: DPTI) to that of the systolic phase (time tension index: TTI) in the central aortic profile has a close correlation with the blood supply to the subendocardium. This ratio was designated as the subendocardial viability ratio: SEVR (DPTI/TTI). We examined the relationships between the SEVR, as measured by SphygmoCor (AtCor Medical Ltd.), and the data from the health examination of 178 males working for a steel company. A significantly low SEVR was observed in people with the smoking habit, a high pulse rate, obesity, abnormality of blood fat components, or hyperglycemia. Employees in the normal SEVR group (SEVR: 140% or more) n = 120 and low SEVR group (SEVR: 139% or less) n = 58 were compared. The results suggested that employees with low SEVR were older and had a higher BMI, higher pulse rate, higher total cholesterol, higher triglyceride, and higher fasting plasma glucose. They also had lower HDL-cholesterol. In the low SEVR group, the percentage of employees with hyperlipidemia or hyperglucosemia was significantly higher than that in the normal SEVR group. Results of stepwise regression analysis indicated that the pulse rate and age were significant and independent predictive factors for SEVR. These data on SEVR calculated from the wave pattern of the central artery are considered to be useful parameters for evaluating the risk of myocardial ischemia and for guiding health promotion.

Hemodynamic cardiovascular risk factors in chronic kidney disease: what are the effects of intervention?

Left ventricular (LV) volume and pressure overload occur frequently in chronic kidney disease (CKD). Anemia is a risk factor for left ventricular hypertrophy (LVH) and dilatation, heart failure, and death. Normalization of hemoglobin with erythropoietin may prevent LVH and dilatation in CKD, but in patients in later phases of their cardiac disease, this intervention is not of benefit. Increased vascular volume causes hypertension, which in turn causes LVH, cardiac failure, and ischemic heart disease (IHD). Manifestations of arteriosclerosis are associated with adverse cardiac outcomes, and angiotensin converting enzyme (ACE) inhibitors may improve LVH and markers of arteriosclerosis. Aortic stenosis in dialysis patients occurs infrequently, but may deteriorate rapidly. The hemodialysis milieu is the quintessential model of LV overload cardiomyopathy.

Peripheral and central arterial haemodynamic interactions are early abnormalities in young male cigarette smokers

BACKGROUND

smoking, result in endothelial dysfunction and this affects systemic and local haemodynamics. The aim was to assess interactions of the left ventricle and arterial system of smokers at baseline and after a physiological stimulus--the cold pressor test (CPT) which causes a sympathetically driven vasoconstriction that counteracts the normal endothelial dependent vasodilatation.

MATERIALS AND METHODS

male smokers and controls were compared using applanation tonometry. Parameters included systolic and diastolic blood pressure, ejection duration, heart rate, aortic augmentation index (AAI), and sub-endocardial viability ratio (SEVR). The CPT was performed at 1 and 3 min following immersion of the hand in ice.

RESULTS

smokers have abnormal baseline cardiac timing (heart rate and ejection duration), systolic and diastolic blood pressures which are due to increased peripheral wave reflection (AAI) and thus affect the SEVR. Following CPT, the pressure wave differential, dP/dt, was significantly increased in smokers compared to non-smokers who had a decrease at 1 min in ice. Mean systolic and diastolic pressure was significantly increased in both groups at 1 and 3 min as was end systolic pressure in non-smokers.

CONCLUSIONS

baseline ventriculo-vascular dynamics, are abnormal as was the evoked response to CPT. The blunted blood pressure increase of smokers compared to controls following CPT, may represent altered nitric oxide production in the macro and microcirculation through differential upregulation of endothelial nitric oxide synthase (eNOS) and inducible NOS respectively. The potential for therapeutic intervention and prevention of ongoing endothelial injury, requires further investigation.

Silent myocardial ischaemia in treated hypertensives with and without left ventricular hypertrophy

BACKGROUND

Silent ischaemia has been reported to be associated with an increased risk of myocardial infarction and sudden death in a wide range of patient groups. The aim of this study was to examine the prevalence of silent ischaemia in hypertensive patients with and without left ventricular hypertrophy (LVH).

METHODS

Twenty hypertensive patients participating in the Anglo-Scandinavian Cardiac Outcomes Trial with echocardiographic LVH (11 males, nine females), and 20 age, sex, blood pressure, and drug treatment-matched hypertensive patients without LVH underwent 24-h combined ambulatory blood pressure and electrocardiographic (ECG) monitoring. Ischaemic events were defined by the 'rule of 3 x 1'-asymptomatic ST-depression >/= 1 mm (0.1 mV), lasting at least 1 min, and with a duration of at least 1 min between two events.

RESULTS

Thirteen patients with LVH had ischaemic events, whilst only four without LVH demonstrated ischaemia. Median numbers of events (seven versus zero; P < 0.01) and median total ischaemic area (0.25 versus 0 mV*min/day; P < 0.01) were significantly increased amongst hypertensive patients with LVH by comparison to those without LVH.

CONCLUSION

Despite similar levels of established risk factors for atherosclerotic coronary artery disease, the prevalence of silent ischaemia was markedly increased amongst hypertensive patients with LVH by comparison to those with normal left ventricular dimensions. Ambulatory ECG monitoring may have a use in the identification of those at greatest risk of cardiovascular complications and sudden death, amongst hypertensive patients with persistent cardiac hypertrophy despite anti-hypertensive therapy.

Ascorbic acid reduces blood pressure and arterial stiffness in type 2 diabetes

Experimental evidence suggests that acute parenteral administration of high-dose ascorbic acid has beneficial vascular effects in type 2 diabetes. We studied the hemodynamic effects of chronic oral supplementation in this condition. Thirty patients, 45 to 70 years of age, with type 2 diabetes, were randomly assigned in a double-blind manner to receive 500 mg ascorbic acid daily by mouth or placebo. Patients were studied at baseline and after 4 weeks of assigned treatment. The central aortic augmentation index (AgIx) and the time to wave reflection (Tr) were derived from radial artery pulse wave analysis data. AgIx and Tr were used as measures of systemic arterial stiffness and aortic stiffness, respectively. Ascorbic acid decreased brachial systolic blood pressure from 142.1+/-12.6 (SD) to 132.3+/-12.1 mm Hg (difference [95% CI] 9.9 [4.7, 15.0]; P<0.01), brachial diastolic pressure from 83.9+/-4.8 to 79.5+/-6.0 mm Hg (4.4 [1.8, 7.0]; P<0.01), and AgIx from 26.8+/-5.5% to 22.5+/-6.8% (4.3 [1.5, 7.1]; P<0.01). Tr increased from 137.1+/-12.6 to 143.4+/-9.2 ms (-6.3 [-10.1, -2.5]; P<0.01). Placebo had no hemodynamic effects, and this difference between treatments was significant (P<0.01 for blood pressure and Tr, P=0.03 for AgIx). We have therefore shown that after 1 month, oral ascorbic acid lowered arterial blood pressure and improved arterial stiffness in patients with type 2 diabetes. As strict control of blood pressure reduces cardiovascular risk in diabetes, ascorbic acid supplementation may potentially be a useful and inexpensive adjunctive therapy. Larger and longer studies now need to be performed.

The impact of arteriovenous fistula formation on central hemodynamic pressures in chronic renal failure patients: a prospective study

BACKGROUND

The presence of an arteriovenous (AV) fistula creates permanently high cardiac output. This may cause an imbalance between available cardiac oxygen supply in response to greater demand and increased arterial stiffness.

METHODS

Surrogate markers of subendocardial perfusion (subendocardial viability ratio [SEVR]) and arterial stiffness (augmentation index [AIx]) can be measured noninvasively by using pulse wave analysis on the radial pulse to obtain central pressures. We prospectively followed up nine patients with chronic renal failure (CRF) undergoing creation of an AV fistula for vascular access at regular intervals over 6 months.

RESULTS

After surgery, blood pressure and heart rate remained unchanged throughout the study period. AIx stayed the same (baseline versus 6 months, 20% +/- 11% versus 22% +/- 15%), but there was a decrease in SEVR immediately after surgery (-9% +/- 5%; P < 0.05) that persisted for at least 3 months (-14% +/- 7%; P < 0.01). At 6 months, SEVR remained below baseline values in all but one patient (mean SEVR at baseline, 166% +/- 22% versus 6 months, 150% +/- 20%; P < 0.05; -9% +/- 7%).

CONCLUSION

Creation of an AV fistula may directly predispose patients with CRF to a risk for myocardial ischemia caused by an adverse imbalance between subendocardial oxygen supply and increased oxygen demand consequent to a greater cardiac output.

Can a clinically useful aortic pressure wave be derived from a radial pressure wave?

BACKGROUND

The information contained in arterial pressure waveforms is probably underused by most clinicians who manage critically ill patients. It is not generally known that an aortic pressure wave can be synthesized by applying a generalized transfer function to the radial arterial pressure wave. We validated a commercially available system, SphygmoCo (PWV Medical, Sydney).

METHODS

Ascending aortic pressure waves were synthesized and comparisons were made between the synthesized aortic waveforms, the measured aortic and radial arterial waveforms. Ascending aortic pressure waves (catheter-tip manometer) and radial artery pressure waves (short fluid-filled catheter) were recorded simultaneously in 12 patients with angina pectoris (age 62-76 years) undergoing cardiac catheterization. Patients were studied at rest, following midazolam, sublingual nitroglycerin and during Valsalva manoeuvres.

RESULTS

Both midazolam and nitroglycerin lowered mean arterial pressure but nitroglycerin caused a more selective decrease in the measured and synthesized aortic systolic pressures than in the radial artery pressure. The synthesized aortic systolic pressure was less, by 6-8 mm Hg (SD 2-3) and the synthesized aortic diastolic pressure greater, by 4 mm Hg (SD 2). Despite these differences in pulse pressure, the synthesized waveform tracked the measured waveform before and during interventions.

CONCLUSIONS

By deriving an aortic waveform from the radial pulse, monitoring of left ventricular afterload can improve without more invasive means.

Reduced arterial distensibility is a predictor of cardiovascular disease in patients after renal transplantation

OBJECTIVE

Arterial distensibility is reduced in end-stage renal failure and also after renal transplantation. The aim of the present study was to test the hypothesis that reduced carotid artery distensibility is a predictor of cardiovascular disease in patients after renal transplantation.

SUBJECTS AND METHODS

Sixty-eight asymptomatic renal transplant recipients were studied between March 1990 and December 1992, 3-6 months after transplantation. The mean duration of follow-up was 95 +/- 2 months (mean +/- SEM). At entry, vessel wall movements of the common carotid artery were recorded using a pulsed multigate Doppler system; blood pressure was measured by sphygmomanometry.

RESULTS

Nineteen cardiovascular events (CVE) occurred during follow-up, leading to death in six cases. The distensibility coefficient of the common carotid artery was significantly lower in patients with CVE than in those without CVE (12.2 +/- 1.0 10-3/kPa versus 16.8 +/- 0.7 10-3/kPa, P < 0.005). Logistic regression analysis showed that the occurrence of cardiovascular disease during follow-up was related to carotid artery distensibility (P < 0.05), independent of sex, age, smoking habits, carotid artery end-diastolic diameter, systolic and diastolic blood pressure levels, heart rate, serum creatinine, cholesterol and haemoglobin levels. Patients with a distensibility coefficient above the age-adjusted mean had a significantly longer interval free of cardiovascular disease than patients with a distensibility coefficient below the age-adjusted mean (P < 0.01).

CONCLUSIONS

The distensibility of the common carotid artery is an independent predictor of cardiovascular disease in renal transplant recipients.