Prehospital 12-Lead ECG to Triage ST-Elevation Myocardial Infarction and Emergency Department Activation of the Infarct Team Significantly Improves Door-to-Balloon Times

Background— American College of Cardiology/American Heart Association guidelines recommend >75% of patients with an ST-elevation myocardial infarction receive primary percutaneous coronary interventions (PPCI) within 90 minutes. Despite these recommendations, this goal has been difficult to achieve.

Methods and Results— We conducted a prospective interventional study involving 349 patients undergoing PPCI at a single tertiary referral institution to determine the impact of prehospital 12-lead ECG triage and emergency department activation of the infarct team on door-to-balloon time (D2BT). The median D2BT of all patients (n=107) who underwent PPCI after field ECG and emergency department activation of the infarct team (MonashHEART Acute Myocardial Infarction [MonAMI] group) was 56 minutes (interquartile range, 36.5 to 70) compared with the median time of a contemporary group (n=122) undergoing PPCI during the same period but not receiving field triage (non-MonAMI group) of 98 minutes (73 to 126.45). The median D2BT time of 120 consecutive patients who underwent PPCI before initiation of the project (pre-MonAMI group) was 101.5 minutes (72.5 to 134; P <0.001). The proportion of patients who achieved a D2BT of ≤90 minutes increased from 39% in the pre-MonAMI group and 45% in the non-MonAMI group to 93% in the MonAMI group ( P <0.001).

Conclusions— The performance of prehospital 12-lead ECG triage and emergency department activation of the infarct team significantly improves D2BT and results in a greater proportion of patients achieving guideline recommendations.

In vivo and in vitro assessment of human saphenous vein wall changes

Purpose:

To investigate if noradrenaline (NA) and 5-hydroxyptamine (5-HT) drugs induce responses of isolated control and varicose veins are altered by removal of the endothelium.

Subjects & Methods:

Specimens of the great saphenous vein (GSV) were obtained from 12 subjects with primary varicose veins and 12 subjects from donor vessels at cardiac surgery. A total of 10 normal healthy volunteers were selected for comparison. The diameter changes of GSV during the resting phase, at the end of 5 minutes occlusion, and then every 30 seconds post deflation for five minutes were measured using B-mode ultrasound. Post-surgery the vein sample was collected in a tube of Krebs-Henseleit solution.

Results:

The repeated measure ANOVA test for the diameter, percent, and difference changes of GSV diameter from maximum diameter at different time intervals showed significance difference within and between all groups. NA and 5-HT produced concentration-dependent contractions of control and varicose saphenous vein segments. There was no significant difference in the potency of NA and for 5-HT, but the maximum response, normalized for tissue weight, was less in varicose vein segments. Removal of the endothelium had no effect on the potency of NA or 5-HT but significantly (p<0.05) reduced the maximum response to NA and 5-HT in varicose vein segments but not to 5-HT in control veins.

Conclusion:

The venous endothelial damage may cause vascular smooth muscle contractions dysfunction that favours dilatation and secondary valvular insufficiency.

Smaller aortic dimensions do not fully account for the greater pulse pressure in elderly female hypertensives

This study examined the importance of aortic dimensions in determining pulse pressure in elderly hypertensives participating in the 2nd Australian National Blood Pressure Study, including a substantial number not previously receiving blood pressure lowering medication. Aortic dimensions were determined by ultrasound at the transverse arch and at the insertion of the aortic valve. Unadjusted data showed negative (P<0.001) correlations between central (carotid) and (brachial) peripheral pulse pressure and both arch (-0.200, -0.181) and outflow tract (-0.238, -0.238) diameters. Correlations were similar in those previously treated with blood pressure lowering medication and in the treatment naïve. Central pulse pressure (84+/-26 versus 75+/-28 mm Hg, P<0.001) was higher and aortic dimensions (transverse arch 2.56+/-0.31 versus 2.88+/-0.35 mm, P<0.001) smaller in women than men. Women had greater aortic stiffness (beta index 29.4+/-36.1 versus 22.1+/-21.3, P<0.03). Other bivariate correlates of central pulse pressure were age, mean arterial pressure, height, heart rate, augmentation index, aortic stiffness (all P<0.001), and weight (P=0.027). In multivariate analyses gender remained a predictor of central pulse pressure (P<0.001) even with inclusion of aortic dimensions (P=0.013) height and weight. Other significant terms were age, heart rate, mean blood pressure, and aortic stiffness (all P<0.001). These findings demonstrate an independent inverse relation between aortic size and pulse pressure in older hypertensive subjects. Differences in aortic dimensions and stiffness between genders do not fully account for the observed blood pressure differences, suggesting that a contributory factor to gender differences in pulse pressure is an increased age-related mismatch in ventricular function and aortic stiffness in women compared with men.

Arterial pulse wave velocity but not augmentation index is associated with coronary artery disease extent and severity: implications for arterial transfer function applicability

OBJECTIVES

The aim of this study was to test the hypothesis that coronary artery disease extent and severity are associated with central aortic pressure waveform characteristics.

BACKGROUND

Although it is thought that central aortic pressure waveform characteristics, particularly augmentation index, may influence cardiovascular disease progression and predict cardiovascular risk, little is known of the relationship between central waveform characteristics and the severity and extent of coronary artery disease.

METHODS

Central aortic waveforms (2F Millar pressure transducer-tipped catheters) were acquired at the time of coronary angiography for suspected native coronary artery disease in 40 patients (24 male). The severity and extent of disease were assessed independently by two observers using two previously described scoring systems (modified Gensini's stenosis and Sullivan's extent scores). Relationships between disease scores, aortic waveform characteristics, aorto-radial pulse wave velocity and subject demographic features were assessed by regression techniques.

RESULTS

Both extent and severity scores were associated with increasing age and male sex (P < 0.001), but no other risk factors. Both scores were independently associated with aorto-radial pulse wave velocity (P < 0.001), which entered a multiple regression model prior to age and sex. This association was not dependent upon blood pressure. Neither score was associated with central aortic augmentation index, by either simple or multiple linear regression techniques including heart rate, subject demographic features and cardiovascular risk factors.

CONCLUSIONS

Aorto-radial pulse wave velocity, but not central aortic augmentation index, is associated with both the extent and severity of coronary artery disease. This has potentially important implications for applicability of a generalized arterial transfer function.

Association of Carotid Intima-Medial Thickness and Indices of Arterial Stiffness With Cardiovascular Disease Outcomes in CKD

BACKGROUND

Indices of arterial structure and stiffness are proposed as surrogate markers of cardiovascular disease in patients with chronic kidney disease (CKD), but no study examined multiple markers in the same population.

STUDY DESIGN

Prospective observational study.

SETTING & PARTICIPANTS

315 subjects with stages 4 to 5 CKD, aged 24 to 79 years (mean age, 56.6 +/- 13.6 [SD] years), enrolled in the Atherosclerosis and Folic Acid Supplementation Trial.

PREDICTORS

Carotid arterial intima-medial thickness (IMT; n = 315) and indices of arterial stiffness (n = 207), including aortofemoral pulse wave velocity (PWV[a-f]), systemic arterial compliance (SAC), and carotid-derived augmentation index.

OUTCOMES

The primary outcome was a composite of all fatal and nonfatal cardiovascular events.

RESULTS

During follow-up (median, 3.6 years), 95 cardiovascular events occurred. On Cox proportional-hazard modeling, mean maximum IMT, PWV(a-f), and SAC were predictive of the composite clinical end point of all cardiovascular events, but carotid-derived augmentation index was not (hazard ratio [HR] for every 0.01-mm increase in IMT, 1.09; P = 0.001; 95% confidence interval [CI], 1.03 to 1.14; HR for every 1-m/s increase in PWV(a-f), 1.18; P < 0.001; 95% CI, 1.12 to 1.25; HR for every 0.01-U/mm Hg decrease in SAC, 0.98; P = 0.01; 95% CI, 0.97 to 0.99). After adjustment for age, sex, blood pressure, diabetes, past cardiovascular disease, cholesterol level, and smoking, PWV(a-f) remained a significant independent predictor of cardiovascular events (adjusted HR, 1.12; P = 0.001; 95% CI, 1.05 to 1.20), but IMT and SAC did not.

LIMITATIONS

Study power to analyze differences between predialysis and dialysis stages of CKD.

CONCLUSIONS

PWV(a-f) is the only arterial index independently associated with cardiovascular outcome in patients with CKD.

‘Generalizability’ of a radial-aortic transfer function for the derivation of central aortic waveform parameters

OBJECTIVE

Arterial transfer functions (TFs) describe the relationship between the pressure waveform at different arterial sites. Generalized TFs are used to reconstruct central aortic waveforms from non-invasively obtained peripheral waveforms and have been promoted as potentially clinically useful. A limitation is the paucity of information on their 'generalizability' with no information existing on the number of subjects required to construct a satisfactory TF, nor is adequate prospective validation available. We therefore investigated the uniformity of radial-aortic TFs and prospectively estimated the capacity of a generalized TF to reconstruct individual central blood pressure parameters.

PATIENTS AND METHODS

Ninety-three subjects (64 male) were studied by simultaneous radial applanation and high-fidelity (Millar Mikro-tip catheter) direct measurement of central aortic BP during elective coronary procedures. Subjects were prospectively randomized to either a derivation or validation group.

RESULTS

Increasing numbers of individual TFs from the derivation group were averaged to form a generalized TF. There was minimal change with greater than 20 TFs averaged. In the validation group, the error in most reconstructed parameters related to the absolute value of the directly measured parameter [systolic blood pressure (SBP) and pulse pressure, P<0.05; systolic pressure-time interval, subendocardial viability index, augmentation index, and times to the inflection point, peak and end systole, all P<0.01]. Aorto-radial delay was related to error in reconstructed central aortic SBP and pulse pressure (negatively) and time to peak systole (positively) (all P<0.001). Reconstruction of augmentation index was poor.

DISCUSSION

Inclusion of more than 20 individual TFs in the construction of a generalized TF does not improve 'generalizability'. There appear to be systematic errors in derived central pressure waveforms and derived aortic augmentation index is inaccurate compared to the directly measured value.

Glucose, insulin, diabetes and mechanisms of arterial dysfunction

1. This commentary reviews and discusses the association between increased arterial stiffness and indices of glucose and insulin metabolism and diabetes mellitus (DM). 2. Diabetes mellitus is associated with increased cardiovascular events, is an established major independent risk factor for cardiovascular disease and is included in current risk assessment algorithms. Based on Framingham risk assessment, the incremental risk due to DM, at a given level of baseline risk in non-diabetics, is approximately equivalent to 10 years and, at any given level of other major risk factors, DM increases risk three- to fourfold. 3. Increased aortic stiffness has been shown to be an independent risk factor for both cardiovascular and overall mortality in high-risk groups and recently in the general population. Both DM1 and DM2 are associated with accelerated stiffening of the elastic arteries, over and above that associated with normal ageing, and DM can be considered as imparting added biological age and, thus, added cardiovascular risk. 4. Aortic stiffness provides a plausible mechanism relating diabetes to increase cardiovascular disease. 5. A proportion of the increased risk of cardiovascular events in DM is a sequel of stiff arteries. Direct measures of arterial stiffness, such as aortic pulse wave velocity, are likely to be better candidates than pulse wave analysis for refining interventions to improve outcomes in diabetes.

Similar Effects of Treatment on Central and Brachial Blood Pressures in Older Hypertensive Subjects in the Second Australian National Blood Pressure Trial

The Second Australian National Blood Pressure Trial reported better prognosis for hypertensive subjects randomly assigned to an angiotensin-converting enzyme inhibitor (ACE-I) compared with a diuretic-based regimen despite no difference in brachial blood pressure control. A possible explanation is that there was a difference in central aortic pressures despite similar brachial pressure reductions. We examined this hypothesis in a subset of the Second Australian National Blood Pressure Trial cohort evaluated both before and after 4 years of treatment. The average age of the 479 subjects was 71.6+/-4.7 years (mean+/-SD), and 56% were women. Brachial systolic and pulse pressures after treatment were 145+/-1 (mean+/-SEM), 143+/-1, 72+/-1, and 70+/-1 mm Hg for diuretic and ACE-I groups, respectively. The respective changes from pretreatment values were -17+/-2, -16+/-2, -9+/-1, and -7+/-1 mm Hg. None of the differences between diuretic and ACE-I groups were significant. Central arterial pressure waveforms were acquired from carotid tonometry and calibrated from brachial pressures. Central systolic and pulse pressures posttreatment were 144+/-2, 144+/-2, 71+/-2, and 72+/-2 mm Hg for diuretic and ACE-I groups, respectively. The respective changes from pretreatment values were -15+/-2, -17+/-2, -6+/-2, and -8+/-2 mm Hg. None of the differences between diuretic and ACE-I groups were significant. The similarity of central and brachial pressures in this cohort of older hypertensive subjects is most likely because of the influences of age and hypertension in increasing arterial stiffness. There is no evidence that the better prognosis for patients randomly assigned to ACE-I in Second Australian National Blood Pressure Trial resulted from a disproportionate lowering of central blood pressure.

Intraocular use of rituximab

PURPOSE

To evaluate the toxicity of 1 mg of intraocular rituximab and to present a small case-series of patients treated with intravitreal rituximab.

METHODS

Rituximab (1 mg/0.1 ml) was injected in the vitreous of one eye of three Dutch-belted rabbits. Two animals were injected with balanced salt solution as controls. At 1 month the rabbits were killed and the eyes examined by light microscopy. Three patients (five eyes) with intraocular lymphoma were also treated with a 1 mg injection of rituximab.

RESULTS

The treated rabbit eyes and the control eyes showed no light microscopic evidence of ocular toxicity at 1 month following injection. The five human eyes of three patients have shown no evidence of intraocular toxicity with a median follow-up time of 3.6 months (range 2.0-6.4 months). One patient received a total of four injections in the right eye and three injections in the left eye.

CONCLUSION

Intravitreal rituximab at a dose of 1 mg does not appear to cause toxicity in rabbit eyes and in the five eyes of three patients.

The use of 31-gauge needles and syringes for intraocular injections

PURPOSE

To describe the use of disposable 31-gauge needles for intraocular injections.

METHODS

Description of the technique and photographs of the needles.

RESULTS

Patients feel the injection less and a smaller postinjection bleb is noted.

CONCLUSION

Consideration should be given to the use of disposable 31-gauge needles or syringes for intraocular injections.

Acute and chronic effects of flavanol-rich cocoa on vascular function in subjects with coronary artery disease: a randomized double-blind placebo-controlled study

Evidence suggests that flavonoid-containing diets reduce cardiovascular risk, but the mechanisms responsible are unclear. In the present study, we sought to determine the effect of flavanol-rich cocoa on vascular function in individuals with CAD (coronary artery disease). Forty subjects (61±8 years; 30 male) with CAD were recruited to a 6-week randomized double-blind placebo-controlled study. Subjects consumed either a flavanol-rich chocolate bar and cocoa beverage daily (total flavanols, 444 mg/day) or matching isocaloric placebos daily (total flavanols, 19.6 mg/day) for 6 weeks. Brachial artery FMD (flow-mediated dilation) and SAC (systemic arterial compliance) were assessed at baseline, 90 min following the first beverage and after 3 and 6 weeks of daily consumption. Soluble cellular adhesion molecules and FBF (forearm blood flow) responses to ACh (acetylcholine chloride; 3–30 μg/min) and SNP (sodium nitroprusside; 0.3–3 μg/min) infusions, forearm ischaemia and isotonic forearm exercise were assessed at baseline and after 6 weeks. FMD, SAC and FBF responses did not differ between groups at baseline. No acute or chronic changes in FMD or SAC were seen in either group. No difference in soluble cellular adhesion molecules, FBF responses to ischaemia, exercise, SNP or ACh was seen in the group receiving flavanol-rich cocoa between baseline and 6 weeks. These data suggest that over a 6-week period, flavanolrich cocoa does not modify vascular function in patients with established CAD.

Brachial Blood Pressure But Not Carotid Arterial Waveforms Predict Cardiovascular Events in Elderly Female Hypertensives

Central arterial waveforms and related indices of large artery properties can be determined with relative ease. This would make them an attractive adjunct in the risk stratification for cardiovascular disease. Although they have been associated with some classical risk factors and the presence of coronary disease, their prospective value in predicting cardiovascular outcomes is unknown. The present study determined the relative predictive value for cardiovascular disease-free survival of large artery properties as compared with noninvasive brachial blood pressure alone in a population of elderly female hypertensive subjects. We measured systemic arterial compliance, central systolic pressure, and carotid augmentation index in a subset of female participants in the Second Australian National Blood Pressure Study (untreated blood pressure 169/88±12/8 mm Hg). There were a total of 53 defined events during a median of 4.1 years of follow-up in 484 women with complete measurements. Although baseline blood pressures at the brachial artery predicted cardiovascular disease-free survival (hazard ratio [HR], 2.3; 95% CI, 1.3 to 4.1 for pulse pressure ≥81 versus <81 mm Hg; P =0.01), no such relation was found for carotid augmentation index (HR, 0.80; 95% CI, 0.44 to 1.44; P value not significant) or systemic arterial compliance (HR, 1.25; 95% CI, 0.72 to 2.16; P value not significant). Blood pressure, but not noninvasively measured central arterial waveforms, predict outcome in the older female hypertensive patient. Thus, blood pressure measurement alone is superior to measurement of arterial waveforms in predicting outcome in this group.

Arterial remodeling correlates positively with serological evidence of inflammation in patients with chronic stable angina pectoris

Positive coronary artery remodeling is associated with unstable coronary syndromes. Serum inflammatory markers, including high-sensitivity CRP (hsCRP), can predict future risk of acute coronary events in patients with stable coronary artery disease. We sought to elucidate the relationship of specific serum inflammatory markers with intravascular ultrasound (IVUS) estimation of coronary artery remodeling in patients with stable coronary artery disease. Thirty-one sequential patients at our institution undergoing IVUS-assisted percutaneous coronary intervention (PCI) with stable coronary artery disease were enrolled. Automated IVUS pullback and offline analysis were performed in all patients. Images were analyzed for vessel wall area (VWA) and lumen area (LA), at the culprit lesion and at a proximal reference site, and the remodeling index (RI) was calculated. Positive and negative remodeling were defined as a RI of > 1.05 and < 0.95, respectively. ELISA essays were performed for soluble VCAM-1, ICAM-1 and E-selectin. The distribution of data followed a lognormal distribution. By defining arterial remodeling as simply positive or negative, significant differences were identified for log E-selectin only (1.80 +/- 0.04 versus 1.62 +/- 0.05, respectively; p = 0.02). The RI correlation coefficient was 0.38 (p = 0.04) for log sVCAM-1 and 0.42 (p = 0.02) for log sICAM-1. The log E-selection and RI correlation coefficient, although weaker at 0.32, showed a trend toward significance (p = 0.08). There was no significant correlation between log hsCRP and RI (p = 0.42). Using step-wise multivariate analysis, log sVCAM-1 only remained an independent predictor of the RI (p = 0.03). Positive coronary artery remodeling correlates with serological markers of inflammation in patients with stable coronary artery disease.

Systemic inflammatory markers in acute coronary syndrome: association with cardiovascular risk factors and effect of early lipid lowering

BACKGROUND

Evidence for statin therapy in prevention of coronary artery disease is overwhelming. In spite of theoretical benefits, any additional advantage of its early introduction in the management of acute coronary syndrome is, however, uncertain. We therefore investigated differences between plasma levels of the systemic inflammatory markers intercellular adhesion molecule-1, vascular cell adhesion molecule-1, E-selectin, C-reactive protein and interleukin-6 in patients presenting with unstable angina or acute myocardial infarction, and assessed whether the 30-day levels of these markers are influenced by early instigation of the HMG-CoA reductase inhibitor pravastatin.

MATERIALS AND METHODS

170 (134 male) patients presenting with acute coronary syndrome, but without previous statin therapy, participated. Blood was taken within 24 h of onset of ischaemic pain and again at 30 days. In all, 87 (71 male) participants were treated with pravastatin (20-40 mg daily) and 83 (63 male) with a matched placebo.

RESULTS

At presentation, interleukin-6 was higher in males than in females (P=0.008) and lower in those with a pre-existing history of myocardial infarction (P=0.038). C-reactive protein and interleukin-6 were greater in myocardial infarction, but this difference was lost at 30 days. Thirty-day changes in all parameters were inversely related to level at presentation but not to treatment with pravastatin. Hypertension (P=0.011) and smoking (P=0.042) were associated with elevation of C-reactive protein with no difference between unstable angina or acute myocardial infarction. The effect of these individual factors was cumulative.

CONCLUSIONS

Interleukin-6 was greater in acute myocardial infarction than in unstable angina; E-selectin was positively associated with a previous myocardial infarction and inversely related to age. We found no effect of early introduction of pravastatin on systemic inflammatory markers 30 days after acute coronary syndrome.

Aortic stiffness affects the coronary blood flow response to percutaneous coronary intervention

We examined the hypothesis that a stiff aorta is associated with reduced coronary blood flow (CBF) and CBF response to percutaneous coronary intervention (PCI). Aortic mechanical properties are thought to affect CBF, with increased stiffness associated with decreased coronary perfusion. Animal studies are conflicting, and human evidence is lacking. Even less is known about the effects of aortic stiffness on the CBF response to successful PCI. In 18 subjects undergoing elective PCI, a Doppler velocity guidewire was positioned proximal to a severe coronary stenosis to measure resting and adenosine-induced hyperemic CBF before and after PCI. Stenosis severity was assessed with Doppler velocity and pressure guidewires. Aortic mechanical indexes measured included central pulse-wave velocity (cPWV) and central pulse pressure (cPP). PCI was successful in all subjects (diameter stenosis: 88 +/- 9% to 2 +/- 7%; coronary flow velocity reserve: 1.8 +/- 0.6 to 3.0 +/- 0.8; fractional flow reserve: 0.57 +/- 0.19 to 0.92 +/- 0.06; all P < 0.001). With the adjustment for age and gender, resting and hyperemic CBF were inversely related to cPWV irrespective of the presence of stenosis (resting: before PCI, r2 = 0.452, P < 0.01; after PCI, r2 = 0.261, P = 0.043; hyperemic: before PCI r2 = 0.503, P = 0.005; after PCI r2 = 0.500, P = 0.002), whereas they were related to cPP in absence of stenosis (resting: r2 = 0.368, P = 0.022; hyperemic: r2 = 0.370, P = 0.016). Hyperemic CBF response (P = 0.005) and hyperemic CBF improvement from PCI (P = 0.025) were less marked in a stiff aorta than a compliant aorta. A stiff aorta is associated with a reduction in CBF, a lower hyperemic CBF response, and may reduce the improvement in hyperemic CBF after successful PCI.

Waveform dispersion, not reflection, may be the major determinant of aortic pressure wave morphology

The objective of this study was to investigate the determinants of aortic pressure waveform morphology in the thoracoabdominal aorta with specific reference to features of potential prognostic value for cardiovascular disease. In particular, we aimed to determine the location of major pressure wave reflection sites within the aorta. Aortic pressure waveforms were acquired with 2-Fr Millar Mikro-tip catheter transducers in 40 subjects (26 men, 14 women), and repeated in 10 subjects, at five predetermined points within the aorta: aortic root, transverse arch, and at the levels of the diaphragm, renal arteries, and aortic bifurcation. Waveforms were analyzed for augmentation index (AI), time to inflection point (Ti), and pressure parameters. AI decreased progressively between the aortic root and bifurcation (P < 0.001), and Ti increased (P < 0.01). There was the expected progressive peripheral amplification of systolic and pulse pressures and fall in time to peak pressure (all P < 0.001). There was no difference on repeat pullback or between sexes. These data are at variance with the concept that central AI results solely from pressure wave reflection, when Ti would be expected to decrease and AI increase with distal progression. Pressure wave propagation phenomena may contribute, and the potential role of frequency dispersion merits investigation.