Gene therapy for the treatment of cardiovascular disease.

Although still experimental at the present time, gene therapy for the treatment of cardiovascular disease is on the horizon. Numerous clinical trials in patients with flow-limiting coronary artery disease are in progress. In order to keep up with advances in gene therapy, critical care nurses must develop a background in this discipline. This challenge rests in the hands of nursing educators to incorporate a sufficient amount of genetic content into the curriculum. Genetics in the curriculum is essential because it is the central science of health care. Genetic discoveries are changing our understanding of the mechanisms of disease and the diagnosis, treatment, and prevention of cardiovascular disease in particular. Gene therapy is likely to influence our daily nursing practice, and nurses must have an adequate knowledge of genetics to provide accurate information to patients and families so that they can make informed decisions about their health care.

Outcomes management for interventional cardiology.

In the evolution of quality assessment activities in interventional cardiology, outcomes management has become the benchmark for demonstrating optimal care. The high volume of interventional cardiology procedures performed each year mandates that efficient, high-quality and cost-effective patient care be delivered to all patients with cardiovascular disease. Although the interventional cardiology procedures represent only a snap shot of the patient's management of coronary artery disease, a long-term plan for positive outcomes is required. A multidisciplinary approach to outcomes management facilitates institutions to be competitive in today's health care market.

Martha N. Hill: transformational leader.

Martha N. Hill, PhD, RN, FAAN, is a world-renowned researcher, educator, and nursing leader. Her election as president of the American Heart Association, effective June 1997, places her in one of the highest regarded positions in the field of cardiology. Despite her success on a national and international level, Dr. Hill has managed to continue to mentor and conduct clinical research with her nursing colleagues and students at The Johns Hopkins University in Baltimore, Maryland.

Acute effects of conjugated estrogens on coronary blood flow response to acetylcholine in men.

Estrogen therapy is associated with a 50% reduction in the clinical manifestations of coronary artery disease in postmenopausal women. Attenuation of coronary vasomotor dysfunction may contribute to estrogen's cardioprotective effects. We hypothesized that conjugated estrogens, which contain several vasoactive estrogenic compounds, may favorably influence the vasomotor response to acetylcholine in men. Twenty men, 56 +/- 5 years of age, referred for clinically indicated coronary angiography, participated in this study. Acetylcholine-induced changes in coronary flow were measured by quantitative coronary angiography and intracoronary Doppler ultrasonography before and 15 minutes after intravenous administration of conjugated estrogens (0.625 mg) in 12 men and placebo in 8 men. Initial acetylcholine infusion resulted in no significant increase in coronary blood flow. However, 15 minutes after estrogen administration repeat acetylcholine infusion caused a mean 32% increase in coronary blood flow from 41 +/- 5 to 54 +/- 8 ml/min (p = 0.02). Acetylcholine-induced change in flow after estrogen was significantly different from that before estrogen (p = 0.03). Placebo administration did not affect acetylcholine-induced changes in coronary flow. Thus, intravenous conjugated estrogens favorably modulate acetylcholine-induced changes in coronary hemodynamics in men. This suggests that novel nonfeminizing estrogenic compounds may have anti-ischemic effects in men.

Long-term estrogen therapy abolishes acute estrogen-induced coronary flow augmentation in postmenopausal women.

Postmenopausal estrogen replacement therapy (ERT) may reduce the clinical manifestations of coronary heart disease by favorably modulating coronary vasoreactivity. Intravenous ethinyl estradiol acutely increases coronary flow in postmenopausal women not receiving ERT. Because several vasoactive agents induce vasomotor tolerance when administered on a long-term basis, we hypothesized that long-term ERT attenuates the acute coronary vasomotor effects of intravenous ethinyl estradiol. To test this hypothesis, coronary hemodynamics were determined before and 15 minutes after intravenous ethinyl estradiol (35 micrograms) in 10 postmenopausal women who were receiving long-term conjugated ERT (group 1) and 10 who had never received ERT (group 2). Estradiol administration in group 1 was not associated with significant changes in coronary flow or resistance. However, women in group 2 exhibited a 28.6% +/- 6.5% (p < 0.001) increase in coronary flow and a 19.9% +/- 3.5% (p = 0.008) decrease in resistance. These results demonstrate that long-term ERT significantly attenuates the response of coronary arteries to the acute vasomotor effects of a high dose of estradiol. This response may be caused by long-term estrogen-induced coronary flow augmentation or to the development of vasomotor tolerance to estrogen.

Clinical evaluation of a microsample coagulation analyzer, and comparison with existing techniques.

A new microsample coagulation analyzer (Hemochron Jr.) has recently been developed which performs a modified activated clotting time (ACT+) and an aPTT by using different reagents. The Hemochron Jr. measures the clotting time of a 5-microliter whole-blood sample by an optical detector and extrapolates the results to the activated clotting time (ACT+) or the plasma-activated partial thromboplastin time by using a validated regression analysis. We compared 124 simultaneous ACT+ and Hemochron ACTs, and 53 paired Hemochron Jr. aPTTs and hospital laboratory aPTTs, in 44 patients during coronary intervention. The Hemochron Jr. aPTT closely correlated with the lab aPTT (r = .79, P < .0001), and the test results were available much more rapidly than the lab aPTT (3.5 +/- 1.1 vs. 56.3 +/- 25.5 min, P = 0.0029). A comparison of duplicate ACT+ measurements did not identify a significant difference in the means (292 +/- 115 sec vs. 293 +/- 112 sec, P = 0.72). The ACT+ closely correlated with the Hemochron ACTs (r = .85, P < .0001). At baseline, the mean ACT+ (175 +/- 43 sec) exceeded the Hemochron ACT (144 +/- 36 sec) by 22% (P < .001). After heparin administration, the mean ACT+ (378 +/- 74 sec) exceeded the Hemochron ACT (332 +/- 65) by 12% (P < .001). The Hemochron Jr. provides a fast and reproducible methodology for measuring ACT and aPTT, using a small blood volume. Further studies are required to determine the optimal anticoagulation range when using the Hemochron Jr. during or after interventional procedures.

Effect of early enalapril therapy on left ventricular function and structure in acute myocardial infarction.

Infarct expansion starts within hours to days after transmural myocardial injury. Previous echocardiographic and left ventriculographic studies demonstrated that angiotensin-converting enzyme (ACE) inhibitor therapy limits left ventricular dilatation, particularly in patients with anterior wall acute myocardial infarction (AMI) or impaired left ventricular function. Forty-three patients with an acute Q-wave AMI were randomized within 24 hours of symptom onset to intravenous enalaprilat (1 mg) or placebo. Patients were then given corresponding oral therapy and followed for 1 month. Predrug and 1-month gated blood pool scans were obtained in 32 patients to evaluate changes in cardiac volumes and ejection fraction. Twenty-three patients underwent magnetic resonance imaging at 1 month to evaluate left ventricular infarct expansion. Blood pressure decreased at 6 hours but returned to baseline in both groups after 1 month of therapy. The change in cardiac volumes from baseline to 1 month differed between the placebo (end-diastolic volume +16 +/- 5 ml, end-systolic volume +8 +/- 6 ml), and enalapril (end-diastolic volume -8 +/- 9 ml and end-systolic volume -14 +/- 7 ml) groups (p < 0.05 vs placebo). Global and infarct zone ejection fractions improved significantly at 1 month in the enalapril group (+6 +/- 3% and 19 +/- 5%, respectively) but did not change over 1 month in the placebo group. Infarct segment length and infarct expansion index by magnetic resonance imaging were significantly less in those treated with enalapril, suggesting less infarct expansion in this group. Thus, early administration of enalaprilat to patients presenting with a first Q-wave AMI prevents cardiac dilatation and infarct expansion.

Primary angioplasty in the acute myocardial infarction setting.

Management of patients experiencing an acute myocardial infarction has evolved dramatically during the past 2 decades. The role and timing of percutaneous transluminal coronary angioplasty in patients experiencing a myocardial infarction has remained controversial and under investigation. In recent studies, it was revealed that direct use of percutaneous transluminal coronary angioplasty in the presence of an acute myocardial infarction appears to be a safe, effective, and economical method of reperfusion.

Comparison of bedside and hospital laboratory coagulation studies during and after coronary intervention.

The activated clotting time is routinely used to monitor anticoagulation during coronary intervention, whereas the hospital laboratory APTT guides pre- and postprocedure heparin therapy. An optimal coagulation test for patients undergoing percutaneous revascularization would provide a rapid and accurate assessment of anticoagulation throughout a broad range of heparin therapy. We studied the relationships of the bedside whole blood APTT, ACT, and the laboratory APTT in 166 patients undergoing coronary intervation. The whole blood APTT correlated closely with the laboratory APTT (range 18-80 sec) (r = .75), whereas the ACT and laboratory APTT had only a fair correlation (r = .42). Also, the whole blood APTT demonstrated a strong correlation with the ACT throughout the range of heparin therapy for intervention (r = .81). The diagnostic accuracy of the whole blood APTT, based on the receiver operating characteristic curve, was significantly better than that for the ACT in determining the anticoagulation status. The whole blood APTT obtained by bedside monitoring provides a rapid and accurate assessment of anticoagulation throughout the range of heparin dosing associated with coronary intervention. In situations in which an adequate assessment of residual anticoagulation is necessary, the whole blood APTT is superior to the ACT and probably should be the method of choice.

High frequency QRS electrocardiography in the detection of reperfusion following thrombolytic therapy.

The hypothesis that an increase in the amplitude (root-mean-square voltage) of the high frequency (150-250 Hz) components of the QRS complex occurs with successful reperfusion following thrombolytic therapy in acute myocardial infarction (AMI) and fails to occur when thrombolysis fails was tested. Clinical markers for successful or failed reperfusion following thrombolytic therapy for AMI are notoriously insensitive. The amplitude of the high-frequency components of the QRS complex decreases during ischemia and returns to normal with resolution of ischemia, but neither the variability in measurement of these potentials nor their patterns of change during the course of AMI have been described. In 32 control subjects, the average coefficient of variation for the amplitude of the high-frequency QRS complex was 10% or 0.3 uV. Based on these data, for the acute infarction population a significant change in this measurement was therefore defined as a change in amplitude > 20% or 0.6 uV on two consecutive recordings. In 30 patients with AMI treated with a thrombolytic agent, either cardiac catheterization, serial serum myoglobin, or complete resolution of ST-segment elevation were used to define successful or failed reperfusion. High-frequency QRS electrocardiograms were obtained at the start of treatment with a thrombolytic agent and for 3 h thereafter using a signal-averaging technique and digital filtering. Standard 12-lead electrocardiograms were obtained at the same time. In patients who reperfused successfully, the high-frequency QRS amplitude increased significantly (1.2 +/- 0.9 uV above its nadir at 83 +/- 36 min after initiation of thrombolytic therapy) in 23 of 25 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

HIV infection, exercise, and immune function.

Decreased physical endurance is viewed by both HIV-infected people and their primary nurses as a major healthcare problem. There is a widespread belief among HIV-infected people that the way to improve their endurance is through exercise. Yet healthcare providers are divided about the role of exercise. This paper presents an overview of decreased endurance as a major problem in this population, with a review of the literature on exercise in healthy and chronically-ill populations, including those with HIV infection, and its effect on immune function.

Brachial approach for intracoronary stent implantation: a feasibility study.

Implantation of coronary artery stents via the percutaneous femoral approach is associated with a high rate of vascular complications at the access site related to the size of the entry hole and the intense anticoagulation required to prevent stent thrombosis. Therefore we studied the feasibility of using the left brachial approach utilizing open arterial repair for implantation of coronary artery stents. Intracoronary stent implantation via the femoral approach in 24 patients (group A) was compared with implantation via the brachial approach in 16 patients (group B). Baseline lesion characteristics were similar in the two groups. All stents in group A (n = 27 stents) were successfully delivered to their target vessel. One stent in group B (n = 18 stents) could not be delivered because of an inability to engage the coronary artery from the brachial approach. There were no significant differences in the angiographic outcome between the two groups. Complications including hematomas, hemorrhage requiring blood transfusion, vascular injury requiring surgery, and pseudoaneurysm formation were significantly more common in group A than in group B (8/24 [33%] versus 1/16 [6%], respectively; p < 0.05). In addition, the length of hospital stay was significantly longer for the femoral approach than the brachial approach (9.4 vs 6.5 days, respectively; p < 0.05). Thus the left brachial approach for intracoronary stent implantation is technically feasible, safe, and associated with fewer local vascular complications and a shorter hospitalization than the femoral approach.

Preprocedural anticoagulation does not reduce angioplasty heparin requirements.

To determine whether continuous preprocedural heparin influences the need for anticoagulation during percutaneous transluminal coronary angioplasty (PTCA), we compared heparin requirements in patients therapeutically anticoagulated after continuous heparinization for > or = 12 hours with patients not pretreated with heparin (controls). A Hemochron device was used to monitor the activated clotting time (ACT) values during the procedure. An ACT > or = 300 seconds was used as a measure of optimal anticoagulation. Patients pretreated with heparin had significantly higher preprocedural ACT measurements (163 +/- 31.5 vs 126 +/- 13 seconds, p < 0.001) and partial thromboplastin time (PTT) measurements (46 +/- 15 vs 25 +/- 3 seconds, p < 0.001) than controls. While the amount of heparin needed to achieve an initial ACT > 300 seconds was slightly greater in control patients (10,682 +/- 1,852 vs 9,269 +/- 2,993 units, p < 0.001), the total heparin required to maintain an ACT > 300 seconds throughout the procedure was similar between the two groups (11,551 +/- 3,181 units vs 12,136 +/- 2,575 units, p = NS). Thus preprocedural anticoagulation does not significantly reduce total heparin requirements, and these patients should receive the same initial heparin regimen as patients not pretreated with intravenous heparin.

Excimer laser angioplasty.

Excimer laser angioplasty is one of the newest procedures being used in interventional cardiology. Because of persistently high rates of restenosis with conventional balloon angioplasty (which may be attributed to the acceleration of atherosclerosis by remodeling and dilatation of diseased arteries) alternatives to remove and debulk atheromatous plaque are being explored. Among these, excimer laser angioplasty (ELA) has been developed as a modality that offers an alternative to percutaneous transluminal coronary angioplasty. The laser energy is delivered via fiberoptics to the target lesion and the plaque material is rendered into a gaseous state (vaporized) by breaking the molecular bonds. With proper training and patient selection, ELA has complication rates that are no higher than conventional balloon angioplasty. Preliminary data indicate that the laser is most successful in treating lesions that are not well treated with conventional balloon angioplasty. These include saphenous vein graft lesions, aorto-ostial lesions, long lesions (> 10 mm in length), moderately calcified stenoses, total occlusions, and percutaneous transluminal coronary angioplasty dilitation failures. The purpose of this article is to review the history and physics of ELA and to provide the nursing professional with an understanding of how the procedure is performed. Nursing considerations when caring for the patient undergoing this procedure are provided.

Myocardial reperfusion injury: the critical challenge.

Oxygen-free radical production and reperfusion injury are complex mechanisms. New and improved methods for maximizing the benefits of reperfusion while minimizing reperfusion injury are on the horizon in the 1990s. Critical care nurses play a crucial role in the assessment, planning, and intervention of patients experiencing the deleterious effects of free radicals and reperfusion injury. Thus, a sound knowledge base in the pathophysiology of reperfusion injury, the detrimental effects of free radicals, and the potential benefits of free-radical scavengers is essential.

Reperfusion and reperfusion injury in acute myocardial infarction.

Recognition of the clinical markers of reperfusion and comprehension of the effects of reperfusion injury in acute myocardial infarction provide a unique challenge for today's critical care nurse. In this article we will explore the processes of reperfusion injury. A review of relevant literature and presentation of a clinical case study and care plan will enable the critical care nurse to construct a larger knowledge base and assist in the nursing management of patients with acute myocardial infarction. Evaluation and treatment of reperfusion and reperfusion injury remains under investigation, but through the skills of assessment, planning, and intervention the critical care nurse can coordinate prompt and appropriate care to the patient with an acute myocardial infarction.