Engaging patients and families to transform heart failure care

For patients with advanced heart failure involvement as a member of the healthcare team is critical to safe, high-quality and goal-directed care. While recognized as an important aspect of care, patient engagement is not yet a standard practice. This presents an opportunity for professional education and development in team-based care. This short report describes the development of a Community and Patient Advisory Team (CPAT) formed to support patient involvement in interprofessional collaborative practice. The CPAT, composed of patient and family advisors, researchers, care team members, and grant operations staff, served as a core team within the structure of a project to shape a new vision of care delivery. This was accomplished through participation in quarterly leadership workshops and facilitation of team training focused on patient-provider communication strategies to improve patient safety. The advisory team led the co-development of patient materials to support patient engagement during the new implementation of structured interprofessional bedside rounds. Involving community members as partners helped shape our work to more effectively and directly address gaps in current patient care.

The use of prophylaxis in patients undergoing diagnostic tests for suspected venous thromboembolism

Objectives

The purpose of this study was to describe the use of pharmacological and mechanical prophylaxis and clinical outcomes of patients undergoing diagnostic tests for suspected venous thromboembolism (VTE).

Methods

The medical records of 660 consecutive inpatients referred for suspected VTE at an academic medical centre were retrospectively reviewed.

Results

Acute VTE was diagnosed in 138 (21%) of the 660 patients; the incidence of deep vein thrombosis and pulmonary embolism was 18–25%, respectively. Only 61% of eligible patients received pharmacological prophylaxis and 43% of patients received mechanical prophylaxis. The incidence of VTE was higher in patients who did not receive pharmacological prophylaxis (30%) compared with patients who did (16%, P value <0.001).

Conclusions

Preventive measures for VTE, including both pharmacological and mechanical prophylaxis, were underutilized in hospitalized patients undergoing diagnostic tests for suspected VTE.

Screening for acute DVT: optimal utilization of the vascular diagnostic laboratory

Since the introduction of venous duplex ultrasound scanning in the early 1980s, many articles have been published describing its use for the diagnosis of deep vein thrombosis (DVT) in symptomatic and asymptomatic high-risk patients. Although technological advances have improved B-mode imaging and Doppler signal processing in the last 2 decades, duplex ultrasonography still has limitations in the diagnosis of acute DVT. Besides those that are technological in nature, there also are limitations because of a lack of standards from one vascular laboratory to another. Studies vary according to the ultrasound techniques used, diagnostic criteria, number and types of patients studied, reimbursement guidelines, and compliance with established standards. Duplex examinations vary from unilateral to bilateral, limited to complete, proximal to distal, and imaging only to imaging combined with Doppler techniques. The sensitivity and specificity of duplex ultrasound for identifying symptomatic proximal DVT are in excess of 95%; however, these drop considerably for asymptomatic DVT in high-risk patients and in patients with isolated calf vein thrombosis. Nevertheless, the utilization of the vascular laboratory to screen for acute DVT in all patients, regardless of the limitations in specific populations, is increasing steadily, whereas reimbursement and the number of technologists available to perform these examinations is decreasing. To achieve optimal utilization of the vascular laboratory, national standards in the form of clinical pathways using evidence from the literature need to be developed and utilized. In addition, referring physicians need to be educated on the accuracy and limitations of duplex ultrasound scanning to avoid both overtreatment and undertreatment of acute DVT.

Venous thrombus stability during acute phase of therapy

The purpose of this study was to use serial venous duplex scans to document the status of deep venous thrombi during the early phase of therapy for acute, deep-vein thrombosis (DVT). A total of 71 consecutive participants treated for a first episode of acute DVT were monitored for new venous thrombosis using serial venous duplex scans. An average of 4.6 duplex scans were performed per patient (range, three to seven) during the 3-week study period. The cumulative incidence of contiguous/non-contiguous extension of the DVT at 3 weeks was 26% (95% CI = 14% to 38%). Nine of the 15 (60%) occurrences were asymptomatic. None of the classical risk factors for DVT was significantly associated with the development of new thrombi. The fraction of time during which the level of anticoagulation was considered 'adequate' (international normalized ratio > or =2.0 and/or heparin concentration > or =0.2 IU/ml) was inversely associated with the risk of extension/new thrombi (p = 0.01, Cox proportional hazards analysis). It was concluded that: (1) the frequency of contiguous/non-contiguous extension of venous thrombosis detectable during the first 3 weeks of therapy was higher than previously reported; (2) the majority of the occurrences were asymptomatic; and (3) the risk of developing this complication was inversely associated with the level of anticoagulation achieved.

Markers of plasma coagulation and fibrinolysis after acute deep venous thrombosis

OBJECTIVE

Plasma markers of coagulation and fibrinolysis have proved sensitive in the initial diagnosis of acute deep venous thrombosis (DVT). The purpose of this study was to examine the evolution and utility of measuring D-dimer and prothrombin fragment 1+2 (F 1+2) levels after an acute DVT.

METHODS

Subjects with DVT confirmed by ultrasonography had quantitative plasma D-dimer and F 1+2 levels determined before anticoagulation. Ultrasound scan and coagulation studies were repeated at 3, 7, and 14 days; 1 month; and every 3 months for 1 year.

RESULTS

Sixty-one patients with a median initial thrombus score of 3 (interquartile range, 2-7) were followed up for 266 days (interquartile range, 91.5-364 days). Initial D-dimer levels were elevated in 92.7% of patients and were associated with thrombus extent (P =.003), whereas F 1+2 levels were increased in 94.5% of patients and were lower in patients with isolated calf vein thrombosis (P =.001). Initial D-dimer (P =.002) and F 1+2 levels (P =.009) were significantly higher in the 26 (43%) patients with recurrent thrombosis during follow-up. Initial D-dimer levels of 2000 ng/mL or greater were predictive of recurrent events after both proximal and isolated calf vein thrombosis. Although interval increases in these markers had little value in detecting recurrent thrombotic events, D-dimer levels of 1000 ng/mL or greater and 500 ng/mL or greater had respective sensitivities of 89.3% and 100% in detecting early and late recurrences. Corresponding specificities were 35.6% and 53.9%.

CONCLUSIONS

Initial D-dimer levels are determined by total thrombus load and remain elevated long after an acute DVT. F 1+2 levels are less sensitive to thrombus score and return to baseline more quickly. Initial levels of these markers may have some utility in predicting the risk of ultrasound scan-documented recurrences, whereas increased D-dimer levels are a sensitive but nonspecific marker of these events.

Deep venous thrombosis and superficial venous reflux

OBJECTIVE

Although superficial venous reflux is an important determinant of post-thrombotic skin changes, the origin of this reflux is unknown. The purpose of this study was to evaluate the frequency and etiologic mechanisms of superficial venous reflux after acute deep venous thrombosis (DVT).

METHODS

Patients with a documented acute lower extremity DVT were asked to return for serial venous duplex ultrasound examinations at 1 day, 1 week, 1 month, every 3 months for the first year, and every year thereafter. Reflux in the greater saphenous vein (GSV) and lesser saphenous vein (LSV) was assessed by standing distal pneumatic cuff deflation.

RESULTS

Sixty-six patients with a DVT in 69 lower extremities were followed up for a mean of 48 (SD +/- 32) months. Initial thrombosis of the GSV was noted in 15 limbs (21.7%). At 8 years, the cumulative incidence of GSV reflux was 77.1% (SE +/- 0.11) in DVT limbs with GSV involvement, 28.9% (+/- 0.09%) in DVT limbs without GSV thrombosis, and 14.8% (+/- 0.05) in uninvolved contralateral limbs (P <.0001). For LSV reflux, the cumulative incidence in DVT limbs was 23.1% (+/- 0.06%) in comparison with 10% (+/- 0.06%) in uninvolved limbs (P =.06). In comparison with uninvolved contralateral limbs, the relative risk of GSV reflux for DVT limbs with and without GSV thrombosis was 8.7 (P <.001) and 1.4 (P =.5), respectively. The relative risk of LSV reflux in thrombosed extremities compared with uninvolved extremities was 3.2 (P =.07). Despite these observations, the fraction of observed GSV reflux that could be attributable to superficial thrombosis was only 49%.

CONCLUSIONS

Superficial venous thrombosis frequently accompanies DVT and is associated with development of superficial reflux in most limbs. However, a substantial proportion of observed reflux is not directly associated with thrombosis and develops at a rate equivalent to that in uninvolved limbs.

Determinants of chronic venous disease after acute deep venous thrombosis

PURPOSE

The purpose of this investigation was to evaluate the relationship between the presenting features of an acute deep venous thrombosis (DVT), the subsequent natural history of the thrombus, and the ultimate outcome as defined according to the Society for Vascular Surgery and the North American Chapter of the International Society for Cardiovascular Surgery reporting standards in venous disease.

METHODS

Patients with an acute DVT were followed with serial clinical and ultrasound examinations. Thrombus extent within 7 venous segments was scored retrospectively according to the reporting standards (scores ranged from 0 to 3), and segmental reflux was scored as present (1) or not present (0). The initial and final thrombus scores, the rates of recanalization and rethrombosis, and the total reflux scores were then calculated from these grading scales and related to ultimate chronic venous disease (CVD) classification.

RESULTS

Sixty-eight patients with an acute DVT in 73 limbs were followed for 18 to 110 months (mean, 55 +/- 26 months). At the completion of the follow-up period, 20 extremities (27%) were asymptomatic (class 0), 13 (18%) had pain or prominent superficial veins (class 1), 25 (34%) had manifested edema (class 3), 13 (18%) had developed hyperpigmentation (class 4), and 2 (3%) had developed ulceration (class 5). In a univariate analysis, CVD classification was correlated with the reflux score (P =.003) but not with the initial or final thrombus score or with the rate of recanalization or rethrombosis. In a multivariate model of features documented at presentation, only the tibial thrombosis score was a significant predictor of CVD classification (R2 =.06). Outcome was better predicted (R2 =.29) with a model that included variables defined during follow-up the final reflux score, the final popliteal score, and the rate of recanalization.

CONCLUSION

The ability to predict the severity of CVD after an acute DVT is currently limited, although the natural history appears more important than the presenting features of the event. The extent of reflux, the presence of persistent popliteal obstruction, and the rate of recanalization are related to ultimate CVD classification, but other determinants remain to be identified.

Effect of compensation method on the behavior of primary care physicians in managed care organizations: evidence from interviews with physicians and medical leaders in Washington State

The perceived relationship between primary care physician compensation and utilization of medical services in medical groups affiliated with one or more among six managed care organizations in the state of Washington was examined. Representatives from 67 medical group practices completed a survey designed to determine the organizational arrangements and norms that influence primary care practice and to provide information on how groups translate the payments they receive from health plans into individual physician compensation. Semistructured interviews with 72 individual key informants from 31 of the 67 groups were conducted to ascertain how compensation method affects physician practice. A team of raters read the transcripts and identified key themes that emerged from the interviews. The themes generated from the key informant interviews fell into three broad categories. The first was self-selection and satisfaction. Compensation method was a key factor for physicians in deciding where to practice. Physicians' satisfaction with compensation method was high in part because they chose compensation methods that fit with their practice styles and lifestyles. Second, compensation drives production. Physician production, particularly the number of patients seen, was believed to be strongly influenced by compensation method, whereas utilization of ancillary services, patient outcomes, and satisfaction are seen as much less likely to be influenced. The third theme involved future changes in compensation methods. Medical leaders, administrators, and primary care physicians in several groups indicated that they expected changes in the current compensation methods in the near future in the direction of incentive-based methods. The responses revealed in interviews with physicians and administrative leaders underscored the critical role compensation arrangements play in driving physician satisfaction and behavior.

Duplex sonography of lower extremity arteries

Although indirect noninvasive tests continue to play a role in the evaluation of patients with lower extremity arterial disease, the direct approach of duplex scanning provides both anatomic and physiological information directly from the involved arterial sites. Experience has shown that the results of duplex scanning are comparable with those of arteriography. The addition of color Doppler imaging to standard duplex scanning expedites the examination by helping to identify vessels and localize flow disturbances. However, precise classification of disease severity still requires spectral waveform analysis. Initial screening of patients with duplex scanning can determine the severity of arterial occlusive disease, the location of the lesions, and which interventional techniques are most appropriate. Arteriography can then be reserved for those patients who are being considered for therapeutic interventions. Duplex scanning has become the primary diagnostic test for follow-up of patients after radiological or surgical procedures and should be considered as an essential component of care for patients with infrainguinal bypass grafts. It has also proven to be valuable for intraoperative assessment and the initial evaluation of suspected vascular trauma in the extremities. Finally, new applications such as compression therapy for pseudoaneurysms continue to evolve and expand the role of duplex scanning in the management of patients with vascular problems.

Acute effects of sublingual nitroglycerin on hepatic blood flow in healthy volunteers

Duplex sonography was used to assess the effects on hepatic blood flow after administering 0.6 mg nitroglycerin (NTG) sublingually to ten healthy volunteers. The study was a randomized, placebo-controlled, cross-over study in which subjects were studied on three separate occasions. Each visit involved administering either placebo or NTG followed by estimation of blood flow through a particular branch of the hepatic artery, portal vein, and hepatic vein every minute for 15 minutes after NTG and placebo administration. Two hours later, subjects were crossed over to the other treatment and the same vessel branch was again examined for 15 minutes. Total blood flow increased 7% in the portal vein and 27% in the hepatic vein during NTG treatment, but did not change significantly in the hepatic artery. Vascular resistance was increased in the hepatic artery and decreased in the portal and hepatic veins after NTG. Qualitatively, flow changed dramatically in the hepatic vein after NTG with the disappearance of normal retrograde flow. The results indicate that nitroglycerin effects hepatic blood flow through the portal and hepatic veins with a decrease in vascular resistance in the portal and hepatic veins and an increase in resistance in the hepatic artery.

Ultrasound determination of total arterial wall thickness

PURPOSE

Ultrasonic measurement techniques for determining intima-media thickness and total arterial wall thickness have been described. The intima-media thickness measurements are currently in use in large epidemiologic trials. Intima-media thickness does not evaluate extramedial atherosclerotic change and so may not fully reflect pathologic changes in the arterial wall.

METHODS

After we performed variability studies of B-mode image acquisition and measurement, we measured total wall thickness and intima-media thickness of the common carotid arteries in 60 adult subjects in three groups: a control group aged 20 to 29 years, a control group aged 60 to 79 years, and a claudication group aged 60 to 79 years. Measurements were made with B-mode ultrasound images.

RESULTS

No statistical difference between sexes was noted. A statistically significant (p < or = 0.05) increase in intima-media thickness and wall thickness was found with increasing age, and an additional increase was observed with clinically significant lower extremity arterial occlusive disease (p < or = 0.05). Image quality had an effect on measurement accuracy.

CONCLUSIONS

The finding that the wall thickness of common carotid arteries is increased in those patients with clinically significant lower extremity disease supports the theory that atherosclerosis affects the arterial wall in a systemic fashion. Because intima-media thickness also increases across subject groups without change in its proportional contribution to the total arterial wall thickness, extramedial arterial changes also occur with aging and the development of atherosclerosis. We propose that because increases in wall thickness measurements of common carotid arteries follow intima-media thickness increase (but do not necessarily measure the same physiologic change) and the wall thickness method can be used in cases when the intima-media thickness cannot be measured, arterial wall thickness measurement may serve as an alternate or confirmatory test of peripheral artery atherosclerotic severity.

Conventional versus high-porosity polytetrafluoroethylene grafts: clinical evaluation

In baboons, nonreinforced (unwrapped) 60 microns internodal distance polytetrafluoroethylene grafts form a complete endothelial lining within 2 weeks by capillary ingrowth through the wall. Smooth muscle cells then grow under the endothelium and proliferate to form a complete neointima. To determine if spontaneous endothelialization of these grafts can also occur in humans, 10 above-knee femoropopliteal grafts composed of equal lengths of 60 and 30 microns polytetrafluoroethylene were placed in eight patients. These grafts were reinforced (wrapped) for human use. Because biopsy of the grafts was not possible, endothelialization was assessed noninvasively by 111In-labeled platelet imaging 1 week and 3 months after surgery. There was no difference in indium uptake between 60 and 30 microns segments at either time. Histologic sections were available from 60 microns segments of two patients who underwent operation for graft thrombosis. Capillary ingrowth was seen in these grafts, but it rarely extended more than half the distance from the outside of the graft to the lumen. Smooth muscle cells were not seen on the flow surface, indicating that a neointima had not formed. These findings demonstrate that capillary ingrowth can occur in 60 microns grafts in humans but does not produce an endothelial lining. The failure to endothelialize is perhaps a result of inadequacy of angiogenesis in adult humans or retardation of capillary ingrowth by the reinforcing wrap.

Accuracy of duplex scanning for measurement of arterial volume flow

This study examined the accuracy of duplex ultrasound measurements of volume flow in a baboon model. Volume flow (Vf) through the external iliac artery was calculated from measurements of blood velocity averaged over several cardiac cycles (time-averaged velocity [TAV]) and vessel cross-sectional area (A) measured from the B-mode image: Vf = TAV x A. Fourteen anesthetized baboons were studied with a duplex scanner with a 7 MHz imaging transducer and 5 MHz pulsed Doppler. B-mode ultrasound measurements of external iliac artery diameters (2.5 +/- 0.2 mm) were used for calculation of cross-sectional area. Timed blood collections obtained through a cannula inserted into the common femoral artery and TAV measurements were obtained simultaneously during 6 to 15-second intervals. These measurements were repeated three to five times per animal with different flow rates each time. Flow rates ranged from 56 to 280 ml/min (170 +/- 54 ml/min). Average velocity was 55 +/- 17 cm/sec. There was no significant difference between the two methods of volume flow measurement (Student t test). Linear regression analysis revealed a high degree of correlation (r = 0.90, slope 0.95, and p = 0.0001). The absolute percentage error was 13% +/- 8%. Volume flow measured by duplex scanning correlates highly with timed blood collections. This method has potential application for the evaluation of diseased arteries and bypass grafts whose rates of flow and waveform patterns are similar to those of this experiment.

Increased blood flow inhibits neointimal hyperplasia in endothelialized vascular grafts

Intimal hyperplasia is a primary cause of failure after vascular reconstruction and may be affected by blood flow. We have studied the effects of increased blood flow on intimal hyperplasia in porous polytetrafluoroethylene grafts implanted in baboons. These grafts develop an endothelial lining by 2 weeks and neointimal thickening due to proliferation of underlying smooth muscle cells by 1 month. Creation of a distal arteriovenous fistula increased flow (from 230 +/- 35 to 785 +/- 101 ml/min, p less than 0.001) and mean shear (from 26 +/- 4 to 78 +/- 10 dynes/cm2, p less than 0.001) without causing a drop in pressure across the grafts. Fistula flow did not alter the pattern of endothelial coverage but did cause a marked reduction in the cross-sectional area of the neointima (from 2.60 +/- 0.52 to 0.42 +/- 0.07 mm2 at 3 months, p less than 0.01). Detailed morphometric analysis revealed an equivalent percentage decrease in smooth muscle cells and matrix content, suggesting that the primary effect of increased flow was to reduce smooth muscle cell number without affecting the amount of matrix produced by individual cells. The neointima remained sensitive to changes in flow at late times; ligation of the fistula after 2 months resulted in a rapid increase in neointimal thickness (from 0.60 +/- 0.03 mm2 after 2 months of fistula flow to 3.88 +/- 0.55 mm2 1 month after ligation of fistula, p less than 0.01). These results support the hypothesis that changes in blood flow affect the structure of diseased as well as normal vessels.

The effects of oral nifedipine on hepatic blood flow in humans

Duplex ultrasonography was used to measure changes in hepatic blood flow in 13 healthy volunteers after they received single doses of 10 mg oral nifedipine and placebo. Blood flow was measured in the hepatic artery and branches of the portal and hepatic veins at baseline and 0.3, 0.6, 1, 1.5, 2, 3, 4, and 5 hours after drug administration. Cardiac output was also measured at baseline and 1, 2, and 3 hours after dosing. Blood flow initially increased in all three vessels 0.6 hour after administration of nifedipine (29%, 56%, and 31% in the hepatic artery, hepatic vein, and portal vein, respectively) compared with placebo. Flow rapidly returned to baseline in the hepatic artery and hepatic vein, whereas it appeared to remain elevated through 3 hours in the portal vein. Nifedipine administration resulted in an increase in cardiac output of 26%, 22%, and 14% above placebo at 1, 2, and 3 hours, respectively. No significant differences were detected in the systolic, diastolic, or mean arterial blood pressures after nifedipine or placebo. This study demonstrates that nifedipine increases hepatic blood flow in a transient nature and systemic hemodynamic parameters do not necessarily reflect specific organ responses. The nifedipine-induced change in blood flow should be considered when nifedipine is coadministered with high-clearance drugs, because systemic availability may be increased.

Disposition of drugs in cystic fibrosis. II. Hepatic blood flow

To determine whether the increased clearance of high extraction-ratio drugs in cystic fibrosis is caused by an increase in hepatic blood flow, the blood flow in main branches of the hepatic vein and portal vein was measured by use of noninvasive duplex ultrasound scanning in 10 adult subjects with cystic fibrosis and in 10 healthy age-, gender-, and height-matched control subjects. No statistically significant differences between subjects with cystic fibrosis and control subjects were detected in either the hepatic vein (217 +/- 103 ml/min for subjects with cystic fibrosis versus 211 +/- 135 ml/min for control subjects) or the portal vein (205 +/- 114 ml/min for subjects with cystic fibrosis versus 190 +/- 101 ml/min for control subjects) blood flows. These data indicate that a large (greater than or equal to 100%) increase in the clearance of high extraction-ratio drugs in patients with cystic fibrosis is unlikely to be primarily caused by an increase in hepatic blood flow. It is probable that alternative mechanisms such as enhanced secretory or metabolic pathways account in large part for increases in clearance of high extraction-ratio drugs.