Doppler Flow Velocity Research Articles

The change in coronary flow after percutaneous coronary intervention in physiologically defined coronary stenoses

BackgroundPercutaneous coronary intervention (PCI) aims to relieve coronary vessel obstruction to improve coronary blood flow and relieve cardiac ischaemia. Some studies suggest little improvement in outcomes compared with medication alone, whereas others suggest that PCI is beneficial if physiologically guided. Few studies have assessed whether PCI improves coronary blood flow and how any change in flow is related to stenosis severity. We sought to determine whether fractional flow reserve (FFR), a pressure-only physiological index of stenosis severity and surrogate for ischaemia, could predict the improvement in coronary flow produced by PCI. MethodsWe assessed 75 stenoses in 67 patients undergoing elective PCI. We conducted simultaneous transtenotic pressure and Doppler flow velocity measurements during adenosine-mediated hyperaemia, both before and after PCI. Flow velocity was calculated over the whole cardiac cycle. Change in flow was stratified by lesion severity, with particular interest to flow changes in stenoses with FFR more than 0·80, which is typically classed as non-ischaemic. FindingsHyperaemic flow velocity was significantly higher after PCI than before PCI (mean 0·30 m/s [SE 0·02] vs 0·51 [0·03], p<0·001) across all stenoses. Both the absolute and relative increase in blood flow after PCI was strongly correlated to the pre-PCI FFR measurement (r=−0·65, p<0·001), with a small non-significant but detectable increase in flow when FFR was borderline (FFR 0·71–0·80: mean change from pre-PCI [Δ] 0·11 m/s [0·07], p=0·14). The greatest incremental increase was seen when FFR in stenoses was less than 0·60 (Δ 0·41 [0·05], p<0·001). By contrast, when pre-PCI FFR was more than 0·80, PCI produced little improvement in flow (0·05 m/s [0·02]) and this change was significantly less than when stenoses were classed before PCI as flow limiting (p<0·001). InterpretationBy removing epicardial stenoses, PCI improves hyperaemic coronary blood flow, and this increase is strongly related to the physiological significance of the stenosis before PCI. Only stenoses defined as severe by FFR, with values consistent with ischaemia, had a significant rise in flow velocity after PCI. Stenoses deemed non-significant by FFR had comparatively little improvement in flow. These findings provide a mechanistic explanation for the improved outcomes and symptomatic improvement after physiologically guided stenting, and strongly support restricting PCI to patients with truly flow-limiting coronary stenoses. FundingUK Medical Research Council.

The effect of maternal supine position on umbilical and cerebral blood flow indices

ObjectiveThe brain sparing phenomenon in the fetus is a protective mechanism aimed at maintaining sufficient blood flow towards the brain during chronic or acute fetal stress, such as that caused by hypoxemia or utero-placental insufficiency. In this study we investigated whether the brain sparing effect can also be elicited by a physiological stress associated with maternal posture.Study design Twenty-three low-risk pregnant women participated in the study. Between 36 and 40 weeks’ gestation, Doppler flow velocity waveforms were obtained from the fetal middle cerebral and the umbilical artery in the supine and the left lateral decubitus positions. Pulsatility index, systolic/diastolic index, and peak systolic velocities were measured and comparison was made between the left lateral and supine positions. ResultsThe pulsatility index in the middle cerebral artery decreased from 1.78±0.27 in the left lateral decubitus position to 1.29±0.16 in supine position (p<0.0001). Peak systolic velocity decreased from 46.05±7.85cm/s to 39.43±7.95cm/s, respectively (p=0.001). The pulsatility index in the umbilical artery decreased from 0.89±0.13 in the left lateral position to 0.74±0.11 in the supine position (p<0.0001). ConclusionsThis study demonstrates that the supine position in late pregnancy, causing aortic and venacaval compression, leads to brain auto-regulation that activates the brain sparing effect in the fetus. This protective mechanism, shown here for the first time to be linked to a physiological stress, may provide the basis for a novel approach in the assessment of fetal wellbeing.

Cardiac surgery during pregnancy: Continuous fetal monitoring using umbilical artery Doppler flow velocity indices

The fetal death rate associated with cardiac surgery with cardiopulmonary bypass (CPB) is as high as 9.5-29%. We report continuous monitoring of fetal heart rate and umbilical artery flow-velocity waveforms by transvaginal ultrasonography and their analyses in relation to events of the CPB in two cases in second trimester of pregnancy undergoing mitral valve replacement. Our findings suggest that the transition of circulation from corporeal to extracorporeal is the most important event during surgery; the associated decrease in mean arterial pressure (MAP) at this stage potentially has deleterious effects on the fetus, which get aggravated with the use of vasopressors. We suggest careful management of CPB at this stage, which include partial controlled CPB at initiation and gradual transition to full CPB; this strategy maintains high MAP and avoids the use of vasopressors. Maternal and fetal monitoring can timely recognize the potential problems and provide window for the required treatment.

THE MATERNAL-FETAL MEDICINE: AN UPDATE

The development of Maternal-Fetal Medicine is contributing to an improvement of maternal well-being and of neonatal health, introducing a number of new and useful technologies. Advances in genomics in the field of prenatal screening and diagnosis allowed the discovery of fragments of cell-free fetal DNA in the maternal circulation and the use of chromosomal microarrays, which can test for microdeletions and microduplications in addition to aneuploidies. Color Doppler applications during pregnancy are expanding exponentially and Doppler flow velocity waveforms indices have provided important information from maternal, placental and fetal circulation with clinical implications. Ultrasound monitoring of fetal growth represents a fundamental tool to evaluate fetal wellbeing and several methods have been developed to improve fetal weight estimation accuracy. The combination of new biophysical and biochemical markers is enriching Maternal-Fetal Medicine and more research will allow to improve pregnancy outcome.

THE MATERNAL-FETAL MEDICINE: AN UPDATE

The development of Maternal-Fetal Medicine is contributing to an improvement of maternal well-being and of neonatal health, introducing a number of new and useful technologies. Advances in genomics in the field of prenatal screening and diagnosis allowed the discovery of fragments of cell-free fetal DNA in the maternal circulation and the use of chromosomal microarrays, which can test for microdeletions and microduplications in addition to aneuploidies. Color Doppler applications during pregnancy are expanding exponentially and Doppler flow velocity waveforms indices have provided important information from maternal, placental and fetal circulation with clinical implications. Ultrasound monitoring of fetal growth represents a fundamental tool to evaluate fetal wellbeing and several methods have been developed to improve fetal weight estimation accuracy. The combination of new biophysical and biochemical markers is enriching Maternal-Fetal Medicine and more research will allow to improve pregnancy outcome.

Linking Intrauterine Growth Restriction and Blood Pressure

Abnormal perfusion to the fetus can slow fetal growth and result in intrauterine growth restriction (IUGR).1 IUGR, or failure to reach one’s birth potential, is one of the most common complications during pregnancy and generally results from placental insufficiency.1 IUGR is generally not recognized before delivery, and treatment options for IUGR are limited, with early delivery being the most common.1 Preeclampsia is often a contributory cause of IUGR, and numerous studies indicate that individuals exposed to a preeclamptic pregnancy exhibit a higher body mass index and blood pressure during childhood and adult life.2 Individuals born with IUGR also demonstrate an increase in blood pressure later in life.3 This association forms the basis for the developmental origins of health and disease and indicates that adverse influences during fetal life that slow fetal growth program an individual for greater cardiovascular risk in later life.4,5 Article see p 2202 Experimental models of placental insufficiency provide proof of principle that IUGR induced by reduced uterine perfusion programs an increase in blood pressure and cardiovascular risk in later life.5 However, in this issue of Circulation , Gaillard et al6 provide a direct link between reduced uterine perfusion and IUGR with increased cardiovascular risk. Using a large, prospective, longitudinal cohort, Gaillard and colleagues report that an increase in third-trimester fetoplacental vascular resistance indicative of reduced perfusion was associated with a decrease in size at birth and a later increase in total fat mass and systolic blood pressure at 6 years of age.6 Thus, this study indicates that assessment of fetal growth characteristics via Doppler flow velocity waveforms in the umbilical artery not only may be indicative of IUGR but also may identify an individual at greater risk …

Therapeutic Hypothermia Reduces Middle Cerebral Artery Flow Velocity in Patients with Severe Aneurysmal Subarachnoid Hemorrhage

Transcranial Doppler (TCD) is widely used to detect and follow up cerebral vasospasm after subarachnoid hemorrhage (SAH). Therapeutic hypothermia might influence blood flow velocities assessed by TCD. The aim of the study was to evaluate the effect of hypothermia on Doppler blood flow velocity after SAH. In 20 patients treated with hypothermia (33°) due to refractory intracranial hypertension or delayed cerebral ischemia (DCI), mean flow velocity of the middle cerebral artery (MFV(MCA)) was assessed by TCD. Thirteen patients were treated with combined hypothermia and barbiturate coma and seven with hypothermia alone. MFV(MCA) was obtained within 24 h before and after induction of hypothermia as well as before and after rewarming. Hypothermia was induced on average 5 days after SAH (range 1-12) and maintained for 144 h (range 29-270). After hypothermia induction, MFV(MCA) decreased from 113.7 ± 49.0 to 93.8 ± 44.7 cm/s (p = 0.001). The decrease was independent of SAH-related complications and barbiturate coma. MFV(MCA) further decreased by 28.2 cm/s between early and late hypothermia (p < 0.001). This second decrease was observed in patients with DCI (p < 0.001), but not in patients with intracranial hypertension (p = 0.715). Compared to late hypothermia, MFV(MCA) remained unchanged after rewarming (65.6 ± 32.1 vs 70.3 ± 36.8 cm/s; p = 0.219). However, patients treated with hypothermia alone showed an increase in MFV(MCA) after rewarming (p = 0.016). Therapeutic hypothermia after SAH decreases Doppler blood flow velocity in both intracranial hypertension and DCI cases. The results can be the effect of hypothermia-related mechanisms or resolving cerebral vasospasm during prolonged hypothermia.

Role of Echocardiography in Patients With Intravascular Hemolysis Due to Suspected Continuous-Flow LVAD Thrombosis

This study sought to characterize the echocardiographic findings of patients presenting with intravascular hemolysis (IVH) due to suspected continuous-flow left ventricular assist device (LVAD) pump thrombosis. LVAD patients who develop pump thrombosis often present with IVH. Echocardiography may be able to detect device dysfunction in this setting. Continuous-flow LVAD patients presenting with IVH due to suspected pump thrombosis were identified. Patients underwent echocardiography with cannula Doppler flow velocity interrogation. Findings were compared with baseline and follow-up studies, and with 49 stable LVAD control patients. Of 145 patients, 14 (10%) had IVH due to suspected pump thrombosis. The mean age was 55 ± 15 years, 93% were men, and 50% received LVAD as destination therapy. Mean duration between implantation and IVH was 231 ± 218 days. Eleven (79%) patients presented with hemoglobinuria, 9 (64%) with jaundice, and 5 (36%) with acute heart failure. Reduced cannula diastolic flow velocity and increased systolic/diastolic (S/D) flow velocity ratio were the only echocardiographic parameters significantly different from controls (outflow cannula 0.3 ± 0.2 m/s vs. 0.8 ± 0.3 m/s, p = 0.03, and 5.9 ± 2.8 vs. 1.7 ± 0.7, p < 0.01, respectively), and were worse for IVH patients with acute heart failure compared with those without (outflow cannula 0.2 ± 0.1 m/s vs. 0.5 ± 0.2 m/s, p = 0.04, and 7.2 ± 3.3 vs. 5.3 ± 2.0, p = 0.02, respectively). Outflow cannula diastolic flow velocity and S/D flow velocity ratio changed significantly from baseline (p = 0.01 and p < 0.01, respectively) in IVH patients, whereas systolic flow velocity did not change (p = 0.59). Odds ratios for outflow cannula diastolic flow velocity and S/D flow velocity ratio for predicting IVH were 0.60 (95% confidence interval [CI]: 0.51 to 0.73), p = 0.02, and 2.45 (95% CI: 2.37 to 2.52) p < 0.01, respectively. Corresponding inflow cannula values were similarly significant. Pump thrombosis was confirmed in 7 (50%) patients after LVAD retrieval. Reduced cannula diastolic flow velocity and increased S/D flow velocity ratio identified continuous-flow LVAD dysfunction in patients with IVH due to suspected pump thrombosis better than other echocardiographic parameters.

Regional and overall aortic function in nondiabetic individuals with insulin resistance and normal glucose tolerance.

Insulin resistance is associated with altered vascular function in diabetes. The objective of the study was to define the overall and regional aortic function as well as the changes of aortic function over time in nondiabetic individuals with insulin resistance and a normal oral glucose tolerance test (OGTT). This was a cross-sectional and longitudinal analysis with 12 months follow-up. The setting of the study was in primary care. Nondiabetic individuals (n = 181, mean age 42 ± 8 y) with a normal OGTT and insulin resistance as defined by the insulin sensitivity index (ISI) participated in the study. ISI was estimated from serial measurements of plasma insulin and glucose during an iv glucose tolerance test. Ascending and abdominal aortic distensibility (AoD) and stiffness index-β (AoSI) were assessed using echocardiography. Carotid-to-femoral artery pulse wave velocity (PWVc-f; an index of overall aortic function) was measured from carotid and femoral arteries Doppler flow velocities recorded simultaneously with an electrocardiogram. Associations between ISI, AoD, AoSI, and PWVc-f were assessed using linear regression analyses and ANOVA. Differences between baseline and 12 months were compared using a paired t test. AoD and AoSI associations as well as changes over a 12-month period in relation to ISI were measured. Ascending AoD (P = .01) and ascending AoSI (P = .025) were significantly associated with ISI; in contrast, abdominal AoD and AoSI and PWVc-f did not. Changes in AoD, AoSI, and PWVc-f over time were more prominent in individuals with low ISI compared with those with high ISI. The significant associations between ISI and aortic function suggest that insulin resistance may affect the cardiovascular system, even when OGTT is normal.

Impaired Cerebral Perfusion After Bilateral Pulmonary Arterial Banding in Patients With Hypoplastic Left Heart Syndrome

Recent studies have shown that bilateral pulmonary artery banding (bil-PAB) for hypoplastic left heart syndrome (HLHS) is not superior to the neonatal Norwood procedure in terms of overall mortality and neurodevelopmental outcome. We tested our hypothesis that bil-PAB is associated with negative hemodynamic effects on cerebral circulation. The acute effects of bil-PAB on cerebral circulation were assessed by serial measurements of cerebral Doppler flow velocities in 9 patients immediately after bil-PAB. To evaluate the chronic effects of bil-PAB on cerebral perfusion, the oxygen demand-supply balance between the lower and upper body, designated as oxygenation balance index (OBI), was calculated in another set of 13 patients using oxymetric data before stage II palliation. Data were compared with those of 13 patients who underwent the Norwood operation. The preoperative cerebral blood flow velocities of the patients were at the lowest levels reported in healthy neonates. Bil-PAB did not increase cerebral blood flow in the first week after the procedure. OBI was significantly lower in patients treated with bil-PAB (p < 0.005) than in those treated with the Norwood procedure, indicating impaired cerebral perfusion after bil-PAB. Importantly, the OBI in the bil-PAB group, but not in the Norwood group, significantly decreased with time after the procedure. In addition, cerebral perfusion was more vulnerable to the changes in pulmonary and systemic blood flow in the bil-PAB group than in the Norwood group. A hybrid approach followed by comprehensive stage II palliation may not be an optimal strategy for HLHS and should be evaluated further.

Renal resistance index: a new marker reflecting cardiorenal syndrome independently associated with heart failure progression

In chronic heart failure (CHF) patients, renal dysfunction assessed by glomerular filtration rate (GFR) has been demonstrated to be independently associated with higher morbidity and mortality rates. The aim of this study was to define whether a novel marker of renal perfusion impairment (Renal Resistance Index, RRI) could play a role in independently predicting heart failure progression. We enrolled 250 outpatients (78% males, 64±13 years, NYHA class 2.2±0.6, left ventricular ejection fraction, LVEF, 34±10%) with CHF (ESC criteria) due to left ventricular systolic dysfunction, in stable clinical conditions (> 1 month) and in conventional therapy. All patients underwent a clinical evaluation, a routine chemestry, an echocardiogram and a renal echo-Doppler. Pulsed Doppler flow recording was performed at the level of a segmental renal artery and RRI was then calculated from the peak systolic Doppler flow velocity and the end-diastolic Doppler flow velocity. During follow-up (17.8±9.9 months), 37 patients experienced heart failure progression (hospitalization, heart transplantation or death due to heart failure worsening). RRI ≥75% was associated with events at univariate (HR: 6,06, 95% CI: 3,04-12,06, p<0.001) as well as at multivariate analysis (HR: 4,461; 95% CI: 1,77-11,3; p: 0.001), after correction for GFR (MDRD formula), age, ischemic cardiomyopathy, NYHA class, arterial pressure, natremia, logNT-proBNP. Figure shows Kaplan-Meier curves for events in patients with RRI<75% and with RRI≥ 75% ![Figure][1] Figure 1 In conclusion, our findings demonstrate the independent role of RRI in predicting heart failure progression of CHF patients. These data suggest that this parameter could be useful in daily clinical practise in order to better characterise patients with cardio-renal syndrome. [1]: pending:yes

Myocardial perfusion distribution and coronary arterial pressure and flow signals: clinical relevance in relation to multiscale modeling, a review

Coronary artery disease, CAD, is associated with both narrowing of the epicardial coronary arteries and microvascular disease, thereby limiting coronary flow and myocardial perfusion. CAD accounts for almost 2 million deaths within the European Union on an annual basis. In this paper, we review the physiological and pathophysiological processes underlying clinical decision making in coronary disease as well as the models for interpretation of the underlying physiological mechanisms. Presently, clinical decision making is based on non-invasive magnetic resonance imaging, MRI, of myocardial perfusion and invasive coronary hemodynamic measurements of coronary pressure and Doppler flow velocity signals obtained during catheterization. Within the euHeart project, several innovations have been developed and applied to improve diagnosis-based understanding of the underlying biophysical processes. Specifically, MRI perfusion data interpretation has been advanced by the gradientogram, a novel graphical representation of the spatiotemporal myocardial perfusion gradient. For hemodynamic data, functional indices of coronary stenosis severity that do not depend on maximal vasodilation are proposed and the Valsalva maneuver for indicating the extravascular resistance component of the coronary circulation has been introduced. Complementary to these advances, model innovation has been directed to the porous elastic model coupled to a one-dimensional model of the epicardial arteries. The importance of model development is related to the integration of information from different modalities, which in isolation often result in conflicting treatment recommendations.

Doppler Flow Velocity and Intra-cranial Pressure: Responses to Short-Term Mild Hypocapnia Help to Assess the Pressure-Volume Relationship After Head Injury

To anticipate an increase in intra-cranial pressure (ICP), information about pressure-volume (p/v) compliance is required. ICP monitoring often fails at this task after head injury. Could a test that transiently shifts intra-cranial blood volume produce consistent information about the p/v relationship? Doppler flow velocities in the middle cerebral arteries (left: 80.8 ± 34.7 cm/s; right: 65.9 ± 28.0 cm/s) and ICP (16.4 ± 6.7 mm Hg) were measured in 29 patients with head injury, before and during moderate hypocapnia (4.4 ± 3.0 kPa). The ratio of vasomotor response to change in ICP differed between those with high (left: 14.8 ± 6.9, right: 14.4 ± 6.6 cm/s/kPa/mm Hg) and low (left: 1.8 ± 0.6, right: 2.2 ± 0.9 cm/s/kPa/mm g) intra-cranial compliance. Additionally, the ratio identified 12 patients deviating from the classic non-linear p/v curve (left: 5.7 ± 1.3, right: 5.8 ± 1.0 cm/s/kPa/mm Hg). They exhibited an almost proportional relationship between vasomotor and ICP responses (R = 0.69, p < 0.01). Results suggest that a test that combines the responses of two intra-cranial compartments may provide consistent information about intra-cranial p/v compliance, even if the parameters derived from ICP monitoring are inconclusive.

Impact of Coronary Microvascular Function on Long-term Cardiac Mortality in Patients With Acute ST-Segment–Elevation Myocardial Infarction

Microvascular function is increasingly being recognized as an important marker of risk in coronary artery disease, and may be accurately assessed by intracoronary Doppler flow velocity measurements. In the setting of ST-segment-elevation myocardial infarction there are limited data regarding the prognostic value of microvascular function in both infarct-related and reference coronary arteries for long-term clinical outcome. We sought to determine the prognostic value of microvascular function, as assessed by Doppler flow velocity measurements, for cardiac mortality after primary percutaneous coronary intervention for acute ST-segment-elevation myocardial infarction. Between April 1997 and August 2000, we included 100 consecutive patients with a first anterior wall ST-segment-elevation myocardial infarction. Immediately after primary percutaneous coronary intervention, intracoronary Doppler flow velocity was measured in the infarct-related artery, to determine coronary flow velocity reserve (CFVR), diastolic deceleration time, and the presence of systolic retrograde flow, as well as in a reference vessel to determine reference vessel CFVR. The primary end point was cardiac mortality at 10-year follow-up. Complete follow-up was obtained in 94 patients (94%). At 10-year follow-up, cardiac mortality amounted to 14%. Cardiac mortality amounted to 5% when reference vessel CFVR was normal (≥2.1), in contrast to 31% when abnormal (<2.1; P=0.001). Reference vessel CFVR <2.1 was associated with a 4.09 increase in long-term cardiac mortality hazard after multivariate adjustment for identified predictors for cardiac mortality (hazard ratio, 4.09; 95% confidence interval, 1.18-14.17; P=0.03) CONCLUSIONS: Microvascular dysfunction, measured by reference vessel CFVR determined after primary percutaneous coronary intervention for acute anterior wall ST-segment-elevation myocardial infarction is associated with a significantly increased long-term cardiac mortality.

The Role of Echocardiography in Patients with Intravascular Hemolysis Due to Suspected Continuous-Flow Left Ventricular Assist Device Thrombus

Purpose Continuous-flow left ventricular assist devices (LVAD) provide hemodynamic support for patients with advanced heart failure (HF). Some patients develop intravascular hemolysis (IVH) due to pump thrombus, although the utility of echocardiography for detecting compromised LVAD circulatory support in this setting is unknown. Methods and Materials Patients with HeartMate II LVADs presenting with IVH due to suspected pump thrombus were identified. Patients underwent echocardiography with Doppler-flow velocity (DFV) interrogation of inflow and outflow cannulae at baseline and presentation. IVH was defined as an acute rise in serum lactate dehydrogenase more than two fold from baseline with supportive clinical symptoms. Results Of 162 patients, 14 (8%) had IVH due to suspected pump thrombus. The mean age was 55±14 years, and duration between implant and presentation was 231±218 days. Eleven patients presented with hemoglobinuria, 9 with jaundice and 7 with acute HF. There was no change in mean inflow or outflow cannula systolic DFV from baseline to presentation (0.9±0.3 to 0.8±0.3 m/sec, p=0.45 and 1.3±0.3 to 1.3±0.4 m/sec, p=0.38), while diastolic DFV declined significantly (0.5±0.3 to 0.2±0.2 m/sec, p Conclusions Reduced cannula diastolic DFV identified LVAD dysfunction in patients with IVH due to suspected pump thrombus more often than other echocardiographic markers of impaired pump function, and was lower in patients presenting with acute HF.

Low Plasma Arginine:Asymmetric Dimethyl Arginine Ratios Predict Mortality After Intracranial Aneurysm Rupture

Asymmetrical dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthases, predicts mortality in cardiovascular disease and has been linked to cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH). In this prospective study, we assessed whether circulating ADMA, arginine:ADMA ratio, and nitrite/nitrate levels were associated with survival and cerebral vasospasm in SAH patients. One hundred and eleven patients were observed day 1 to 15 after SAH, with serial measurements of transcranial Doppler flow velocities (VMCA) and plasma biomarkers. Clinical status was assessed by the World Federation of Neurosurgical Societies grading scale. Overall 30-day mortality was 18%, but differed between patients grouped by low, midrange, and high arginine:ADMA ratio in the first week after SAH. Mortality rates were 14/37, 1/37, and 5/37 in the 3 groups, respectively (P-logrank=0.0003). Cox regression showed that low versus midrange or high arginine:ADMA was associated with a hazard ratio of 4.1 independent of World Federation of Neurosurgical Societies grade (95% confidence interval, 1.5-10.9; P=0.006). ADMA or arginine:ADMA had no association to VMCA, but there was an inverse relationship between VMCA and nitrite/nitrate levels (P<0.0001). The NOS3 894G/G genotype was associated with 15% lower VMCA (P=0.01). ATbG-NOS3 haplotype homozygosity was associated with up to 64% higher nitrite/nitrate levels (P=0.003). This study suggests that plasma arginine:ADMA ratios predict mortality after SAH. Both clinical and physiological measures of changes in cerebral hemodynamics are coupled to the nitric oxide system.

A Transesophageal Echocardiography Technique to Locate the Kidney and Monitor Renal Perfusion

Monitoring the renal arterial Doppler flow velocity indices, the resistive index and pulsatility index, with ultrasound may help predict renal dysfunction. However, such monitoring has been done intermittently by transcutaneous ultrasound in the postoperative intensive care setting. In the operating room, transesophageal echocardiography (TEE) is an alternative to transcutaneous ultrasound for obtaining indices of renal perfusion. However, it is difficult to locate the right kidney using TEE. We propose a new technique to locate the left kidney that, in our experience, is simple and easy to perform. We believe, starting from a transgastric left ventricular short-axis view, turning left to locate the abdominal aorta, and following it to the origin of the left renal artery may help locate the left kidney faster than previously described techniques. We also propose a new technique to monitor these Doppler indices using TEE during the intraoperative period.

Effects of antihypertensive therapy on glucose, insulin metabolism, left ventricular diastolic dysfunction and renin system in overweight and obese hypertensives

We attempted to test the hypothesis that the direct renin inhibitor aliskiren can improve diastolic dysfunction, glucose, and insulin metabolism (GIM) in overweight and obese hypertensive patients. Seventy-eight hypertensive patients were divided into two groups: 38 treated with aliskiren for six months, and 40 treated without aliskiren but with only traditional anti-hypertensive therapy, as controls. Doppler mitral flow velocity patterns were assessed before and after aliskiren during a six-month period. GIM (three-hour intravenous glucose tolerance test) was measured after four to six weeks of washout and six months of treatment. The mitral E/A ratio increased from 0.65 ± 0.11 to 0.75 ± 0.19. None of the indexes changed in the control group. In the control group, GIM parameters, fasting glucose levels (5.3 ± 0.9 to 6.0 ± 1.5 mmol/l; p = 0.003), fasting insulin levels (121 ± 121 to 189 ± 228 pmol/l; p = 0.03), and most other relevant metabolic measures (p < 0.05 for all) significantly worsened. Aliskiren did not affect GIM. In the control group LVM/height was not affected (119 ± 12 to 120 ± 17 g/m; p = 0.8), whereas aliskiren significantly reduced LVM/height (120 ± 13 to 111 ± 19 g/m; p = 0.04). Optimal target BP was achieved in the group as a whole and in both obese patient groups, while benefits to cardiac structure were of a smaller magnitude. In high-risk, overweight/obese patients with hypertension, traditional therapy provides significantly greater BP- versus aliskiren-lowering throughout the 24-hour dosing interval. Therefore in obese, hypertensive individuals, adequate and similar blood pressure control was achieved with aliskiren; however, the aliskiren group and not the control group was associated with a more favorable GIM profile and led to a significant regression of LVM; overall aliskiren-based treatment offers sustained control of PRA.

Pre-eclampsia or chronic kidney disease? The flow hypothesis

Chronic kidney disease (CKD) and pre-eclampsia (PE) occur in 3-5% of pregnancies. They often share hypertension and proteinuria and a differential diagnosis may be impossible. However, in PE, the pathogenesis is related to abnormal placentation, which can be detected by abnormal uterine and umbilical Doppler flow velocities, while in CKD, an intrinsic kidney disease is present. We hypothesize that Doppler studies can help to differentiate PE from CKD, as the flow velocities are altered in PE and normal in CKD. We retrospectively selected patients who were followed in our Materno-Foetal Unit (2005-10) and had at least one flow measurement in our setting. CKD patients were included in the presence of proteinuria (≥ 300 mg/day) and hypertension, mimicking PE. The clinical charts were reviewed by the same operators; the clinical diagnoses were taken as reference. Three flow patterns were considered: alteration of both flow velocity waveforms (FVWs) (uterine and umbilical arteries), hypothesized as predictive of PE; normal FVWs at both levels, hypothesized as predictive of CKD; altered FVW in either artery, considered 'mixed'. Uterine FVWs were considered pathological according to the classical cut-point (RI > 0.58). Umbilical flows were evaluated according to standards adjusted for gestational age. Statistical analysis was performed in SPSS. The analysis included 61 cases. The presence of normal FVWs was significantly associated with the diagnosis of CKD (P = 0.0018). Conversely, the presence of both altered flows was significantly associated with PE (P = 0.0233). In the presence of proteinuria and hypertension, normal flows suggest CKD altered flows PE. Prospective studies are needed to refine this hypothesis based on the first Doppler criteria supporting the differential diagnosis between CKD and PE.

A Program of 3 Physical Therapy Modalities Improves Peripheral Arterial Disease in Diabetes Type 2 Patients

Type 2 diabetes is one of the main causes of peripheral vascular disease. The beneficial effects of exercise on glucose homeostasis include a marked stimulation of blood glucose utilization during and after its performance. The objective of this study was to determine the effects of a program of 3 physical therapy modalities on blood circulation in patients with type 2 diabetes with peripheral arterial disease. A randomized controlled trial was undertaken. Sixty-eight patients with type 2 diabetes with Leriche-Fontaine stage I or IIa peripheral arterial disease were randomly assigned to an exercise or placebo group. For 20 weeks, the exercise group underwent treatment comprising 3 exercises at proximal, medium, and distal segments of the lower limbs, and the placebo group received sham treatment with disconnected ultrasound equipment. Peripheral arterial disease was determined by evaluating the ankle/brachial index (ABI), Doppler flow velocity, blood parameters, cardiovascular risk score, and heart rate during exercise test. After 20 weeks of treatment, significant differences between groups were found in the following: right (P < .039) and left (P < .023) ABI; Doppler flow velocity (cm/s) in the right (P < .010) and left (P < .026) posterior tibial artery and in the right (P < .012) and left (P < .022) dorsalis pedis artery; and fibrinogen (P < .045), hemoglobin (P < .021), cholesterol (P < .012), high-density lipoprotein cholesterol (P < .031), and HbA1c (P < .034) values. There was no significant difference in low-density lipoprotein cholesterol values (P < .110) between the groups. A program of these physical therapy modalities improves ABI, Doppler flow velocity, and blood parameters in patients with type 2 diabetes.