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Biomedical subjects

G Flaker

Publications and source records attributed to G Flaker.

16 recordsLinked to original sources
PubMed2006

Rationale and design of ACTIVE: the atrial fibrillation clopidogrel trial with irbesartan for prevention of vascular events.

BACKGROUND: Atrial fibrillation (AF) is the most frequently occurring cardiac arrhythmia with often serious clinical consequences. Many patients have contraindications to anticoagulation, and it is often underused in clinical practice. The addition of clopidogrel to aspirin (ASA) has been shown to reduce vascular events in a number of high-risk populations. Irbesartan is an angiotensin receptor-blocking agent that reduces blood pressure and has other vascular protective effects. METHODS AND RESULTS: ACTIVE W is a noninferiority trial of clopidogrel plus ASA versus oral anticoagulation in patients with AF and at least 1 risk factor for stroke. ACTIVE A is a double-blind, placebo-controlled trial of clopidogrel in patients with AF and with at least 1 risk factor for stroke who receive ASA because they have a contraindication for oral anticoagulation or because they are unwilling to take an oral anticoagulant. ACTIVE I is a partial factorial, double-blind, placebo-controlled trial of irbesartan in patients participating in ACTIVE A or ACTIVE W. The primary outcomes of these studies are composites of vascular events. A total of 14000 patients will be enrolled in these trials. CONCLUSIONS: ACTIVE is the largest trial yet conducted in AF. Its results will lead to a new understanding of the role of combined antiplatelet therapy and the role of blood pressure lowering with an angiotensin II receptor blocker in patients with AF.

Aged↗
PubMed2000

Benefits of lipid lowering on vascular reactivity in patients with coronary artery disease and average cholesterol levels: a mechanism for reducing clinical events?

BACKGROUND: The favorable effects of lowering low-density lipoprotein (LDL)-cholesterol on reducing clinical events in patients with coronary disease have been well established. The mechanisms responsible for this benefit, however, have not been fully understood. This study examined the impact of lipid-lowering therapy on endothelium-dependent vasoreactivity in a subgroup of patients after myocardial infarction with average cholesterol levels who participated in the Cholesterol Recurrent Events (CARE) study to determine whether an effect on endothelial function is a viable mechanism for the observed reduction in clinical events. METHODS AND RESULTS: Participants were recruited from among volunteers in the CARE trial at 2 university-based outpatient cardiology clinics. Patients were randomly assigned to pravastatin or placebo. Plasma lipids were measured at baseline and semiannually thereafter. During the final 6 months of the trial, vasoreactivity was assessed by change in ultrasound-determined brachial artery diameter in response to blood pressure cuff-induced ischemia (endothelium-dependent) and to nitroglycerin, a direct vasodilator. Differences in response were examined between the 2 randomized groups. The relation between change in LDL-cholesterol from baseline to year 5 and the magnitude of endothelium-dependent vasodilation also was examined. There was significantly greater endothelium-dependent vasodilation observed in the pravastatin group compared with the placebo group (13% vs 8%, P =.0002), with no difference between the groups in their response to the endothelium-independent vasodilator nitroglycerin. The magnitude of the endothelium-dependent vasodilation was significantly correlated with the percent change in LDL-cholesterol from baseline to final visit (r = 0.49, P =.015). CONCLUSIONS: These findings indicate that the use of pravastatin in patients after myocardial infarction with average cholesterol levels is associated with greater endothelium-dependent vasodilation compared with those who received placebo. The magnitude of this vasodilatory response is correlated to the reduction in LDL-cholesterol. This improvement in endothelium-dependent vasoreactivity may be a likely mechanism, at least in part, for the reduction in recurrent clinical events observed and reported in the CARE study.

Adult↗
PubMed2000

The mode selection trial (MOST) in sinus node dysfunction: design, rationale, and baseline characteristics of the first 1000 patients.

BACKGROUND: More than 200,000 permanent pacemakers will be implanted in the United States in 2000 at a cost of more than $2 billion. Sick sinus syndrome (SSS) will likely account for approximately half of all cases necessitating implantation. Pacemaker technology permits the selection of ventricular (single-chamber) or dual-chamber devices. However, clinical and outcomes data are inadequate to support a clear recommendation that one or the other type of device be used. METHODS: The Mode Selection Trial (MOST) is a single-blind study supported by the National Heart, Lung, and Blood Institute designed to enroll 2000 patients with SSS. All patients will receive a DDDR pacemaker programmed to VVIR or DDDR before implantation. The average time of follow-up will be 3 years. MOST has a >90% power to detect a 25% reduction in the primary end point-nonfatal stroke or total (all cause) mortality-in the DDDR-treated group. Secondary end points will include health-related quality of life and cost effectiveness, atrial fibrillation, and development of pacemaker syndrome. Prespecified subgroups for analysis will include women and the elderly. Enrollment was completed in October 1999, with a total of 2010 patients. RESULTS: The median age of the first 1000 enrolled patients is 74 years, with 25% of patients 80 years or older. Women comprise 49%, and 17% are nonwhite, predominantly black (13%). Before pacemaker implantation, 22% of patients reported a history of congestive heart failure, 11% coronary angioplasty, and 25% coronary bypass surgery. Supraventricular tachycardia including atrial fibrillation was present in 53% of patients. A prior stroke was reported by 12%. Antiarrhythmic therapy was in use in 18% of patients. CONCLUSIONS: MOST will fill the clinical need for carefully designed prospective studies to define the benefits of dual-chamber versus single-chamber ventricular pacing in patients with SSS. The MOST population is typical of the overall pacemaker population in the United States. Thus the final results of MOST should be clinically generalizable.

Aged↗
PubMed1995

Physical working capacity after acute myocardial infarction in patients with low ejection fraction and effect of captopril.

Previous studies after acute myocardial infarction (AMI) have reported conflicting results on the effects of angiotensin-converting enzyme inhibition on physical working capacity. In an effort to provide more insight into this subject, we examined the effects of captopril on working capacity of patients who had low ejection fractions but no congestive heart failure after AMI. One hundred sixty-six participants were recruited from 5 centers after randomization to either captopril or placebo for the Survival and Ventricular Enlargement study. Upright cycle ergometer tests were performed with continuous measurements of respiratory gases at 4, 12, and 24 months after AMI. Our study concurs with 2 of 3 previous post-AMI studies and supports the conclusion that working capacity is not affected by angiotensin-converting enzyme inhibition at 4 or 12 months after AMI in patients without congestive heart failure. In addition, no significant effect of captopril was noted at 24 months after AMI. Peak oxygen uptake tended to decrease between 12 and 24 months in the placebo group by an average (+/- SD) of -22 +/- 322 ml/min (n = 66), but to increase in the captopril group (+62 +/- 289, n = 57), a difference that was significant (Mann-Whitney chi-square, p = 0.02). This post-hoc observation suggests that a late beneficial effect may have been masked by inadequate study duration. Known benefits of captopril appear not to include an increase in working capacity within the first 24 months after AMI.

Aged↗
PubMed1992

Comparison of subxiphoid and traditional approaches for ICD implantation.

We compared clinical and electrophysiological data in 18 patients undergoing ICD implantation via a traditional (median sternotomy or left lateral thoracotomy) with 29 patients with a subxiphoid approach. Both groups were similar in terms of age, sex, left ventricular ejection fraction, presence of coronary artery disease, and clinical indication for the device. Fifteen patients (83%) with the traditional approach had previous cardiac surgery compared with 6 patients (21%) who had a subxiphoid approach (P < 0.001). Both groups had similar patch R wave and sensing R wave measurements. Patients with the traditional approach had a lower energy for defibrillation than patients with a subxiphoid approach (13.6 +/- 6.8 J vs 17.9 +/- 4.1 J, P < 0.05). Postoperative hospital days were fewer in the subxiphoid group compared with the traditional approaches (9.8 +/- 5.3 vs 13.7 +/- 7.5 days) but the differences did not reach statistical significance, possibly due to small numbers. The subxiphoid approach appears to be a reasonable alternative approach to the traditional approach in selected patients undergoing ICD implantation.

Defibrillators, Implantable↗
PubMed1990

The effect of multiple shocks on canine cardiac defibrillation.

To determine if multiple shocks adversely affect the success of later shocks compared with early shocks, we analyzed the success rates of initial shocks (defibrillation attempts 1-5), first half shocks (defibrillation attempts 1-20) and second half shocks (defibrillation attempts 21-40) in a canine model. Epicardial patches were placed on the right and left ventricle in 28 dogs. Ventricular fibrillation was induced by a 60-Hz shock. After 30 seconds, defibrillation was attempted using 7, 12, 13, or 18 joules with either a uniphasic or biphasic rectangular waveform. The uniphasic waveform was 5 msec in duration; the biphasic waveform was 10 msec, with the lagging 5-msec pulse one-half the amplitude of the leading 5-msec pulse. For uniphasic shocks, the right ventricular patch was positive; for biphasic shocks, the right ventricular patch was positive during the leading 5 msec of the shock and negative during the lagging milliseconds. A total of 960 fibrillation episodes were evaluated; no dog was involved in more than 40 fibrillation episodes. The success rates of defibrillation attempts 1-5, defibrillation attempts 1-20, and defibrillation attempts 21-40 were similar at 12, 13, and 18 joules. This information supports the continued use of up to 40 fibrillation trials in canine cardiac defibrillation. However, at 7 joules defibrillation attempts 21-40 were more successful than defibrillation attempts 1-5, and 1-20. With our methodology, these data are consistent with the hypothesis that low energy shocks create a "sensitizing" effect on cardiac tissue, allowing more successful defibrillation with repeated shocks.

Animals↗
PubMed1989

Panic disorder in patients with chest pain and angiographically normal coronary arteries.

Although patients with angiographically normal or near normal coronary arteries are at low risk for cardiac disease, several follow-up studies have shown that many continue to report recurrent chest pain associated with social and work dysfunction. Three diagnostic entities have been proposed to explain the morbidity of this group: microvascular angina, esophageal motility disorders and panic disorder. The purpose of this study was to test the hypothesis that panic disorder is found frequently in patients with chest pain who have normal epicardial vessels. Ninety-four subjects with angiographically normal coronary arteries were interviewed according to a structured psychiatric protocol within 24 hours of their catheterizations. Thirty-two (34%) fit Diagnostic and Statistical Manual of Mental Disorders (third edition, revised) criteria for current panic disorder. Because panic disorder can be effectively treated, physicians should consider this diagnosis in this group of patients. Current research findings suggest that panic disorder, microvascular angina and esophageal disorders may each form the basis for chest pain in approximately 25% of these patients. Miscellaneous problems account for the other 25%.

Adult↗
PubMed1989

Pharmacotherapeutic treatment of panic disorder in patients presenting with chest pain.

While psychiatric populations with panic disorder have been shown to be responsive to several classes of psychoactive medications, there is little evidence that medical patients with panic disorder respond to similar interventions. In this non-blind, eight-week trial of alprazolam in patients presenting with chest pain and found to have panic disorder, 15 of 20 met the single criterion for improvement: a 50 percent or greater reduction in panic frequency. Several other measures were also significantly positive for those who completed the study. Furthermore, these patients reported a marginally significant drop in episodes of chest pain or discomfort. A double-blind, placebo-controlled trial is now required to test the validity of these findings.

Adult↗
PubMed1988

Panic disorder, cardiology patients, and atypical chest pain.

Although patients with angiographically normal coronary arteries have low mortality, several studies have indicated that their social and work morbidity is high. Panic disorder appears to be a major contributor to the continuing chest pain in this population. There are also many chest pain patients appearing in cardiology clinics who also do not have heart disease but who are not given the opportunity to be evaluated for psychiatric disorders. Among those presenting with atypical or nonanginal chest pain, panic disorder represents a likely etiologic consideration. The fact that such patients do exist in cardiology populations is further substantiated by an open-label trial of alprazolam which demonstrated a positive effect in patients selected from those with atypical chest pain and no heart disease found to fit panic disorder criteria. These findings strongly support the increasing affiliation between cardiology and psychiatry and reinforce the belief that many problems of the heart may be problems of the mind/brain.

Angina Pectoris↗
PubMed1988

Intra-aortic balloon cardiac assist: complication rates for the surgical and percutaneous insertion techniques.

A retrospective study was performed to evaluate complications with the two most common intra-aortic balloon pump (IABP) insertion techniques. During a nine year period, 202 patients (51 women, 151 men) underwent IABP cardiac assist utilizing the arteriotomy surgical (103 balloons) and percutaneous (99 balloons) insertion techniques. Complications, including asymptomatic loss of pedal pulse, vascular-symptomatic, infection, or balloon rupture occurred in 22.8 per cent of patients. Of the 54 complications, 13 (24%) were asymptomatic loss of pedal pulse, 36 (66.7%) were vascular symptomatic, three (5.5%) were infection, and two (3.7%) were balloon malfunctions. The overall complication rates were 16/103 (15.5%) and 38/99 (38.3%) for the surgical and percutaneous methods, respectively (P = 0.007). Thirty two per cent (33/103) of the patients receiving IABP surgically and 24 per cent (24/99) of those receiving IABP percutaneously died in the hospital (P = 0.34); no death was directly attributable to IABP. The number of patients requiring surgical intervention or removal was not significantly different between the surgical and percutaneous methods (9 versus 18%, P = .06). While the method of IABP insertion did not significantly alter hospital mortality, a significantly greater complication rate was observed with percutaneous insertion (P = .007). This was particularly relevant to complications occurring at the time of removal of IABP.

Adolescent↗
PubMed1987

Atypical or nonanginal chest pain. Panic disorder or coronary artery disease?

Of 195 patients with atypical or nonanginal chest pain presenting in a cardiology clinic, 104 consented to be evaluated for anxiety disorders using a structured psychiatric interview. Thirty patients had histories of coronary artery disease (CAD). Fifty-nine patients in the sample (16 of those with CAD and 43 of those without CAD) fit diagnostic criteria for panic disorder (PD). Those without CAD and with PD were primarily women (mean age, 43 years) with predominantly nonanginal chest pain. Those patients with both CAD and PD were primarily men (mean age, 54 years) with predominantly atypical angina. Since PD has been shown to be readily responsive to pharmacologic intervention, this diagnosis should be considered in patients with atypical or nonanginal chest pain.

Adolescent↗
PubMed1986

Influence of atrioventricular synchrony on hemodynamics in patients with normal and low ejection fractions following open heart surgery.

The authors wished to test the hypothesis that atrioventricular synchrony has a relatively greater effect on hemodynamic parameters in postoperative patients with low ejection fractions compared to those with normal ejection fractions. Temporary pacing wires were placed on the right atrium and right ventricle of patients undergoing open heart surgery. Duplicate thermodilution cardiac outputs were determined during atrial pacing and ventricular pacing at 100 beats/min. Mean left atrial and systemic blood pressures were monitored. Thirteen patients with ejection fractions of 45 per cent or less (range 24 to 45%, mean 37.3%) were included in the low ejection fraction group, and 27 patients with ejection fractions of 59 per cent or greater (range 59 to 80%, mean 66.8%) were considered in the normal ejection fraction group. All hemodynamic parameters improved significantly when changing from ventricular pacing to atrial pacing in both the normal ejection fraction group and low ejection fraction group (P less than 0.05). The magnitude of change between the groups showed no significant difference for all parameters except left atrial pressure, which decreased by a greater percentage in the low ejection fraction group with atrial pacing (P less than 0.001). The atrial contribution to hemodynamic enhancement is important in patients with normal and low ejection fraction following open heart surgery. Patients with low ejection fractions do not sustain a relatively greater reduction in cardiac output, stroke volume index, or systemic blood pressure with loss of atrioventricular synchrony when compared to patients with normal ejection fractions.

Cardiac Output↗
PubMed1983

Supravalvular aortic stenosis. A 20-year clinical perspective and experience with patch aortoplasty.

Supravalvular aortic stenosis has a wide range of clinical and morphologic expression. Since 1961, 25 patients (aged 1 to 49 years) with documented supravalvular aortic stenosis have been evaluated. Seven (28%) had Williams' syndrome, 5 (20%) had a familial form of supravalvular aortic stenosis, and 13 (52%) had a sporadic form. A blood pressure difference of greater than 10 mm Hg between the arms was noted in 65% of the patients. Angiographically, 19 (76%) had segmental supravalvular narrowing; 6 (24%) had diffuse narrowing of the ascending aorta. Sixteen patients underwent patch aortoplasty. At surgery, portions of the aortic valve cusps were frequently attached to supravalvular tissue. This "cusp tuck" resulted in distinctive angiographic features and influenced the results of corrective surgery. Three surgical deaths occurred in the early 1960s-2 with diffuse narrowing of the aorta. Of the remaining 12 patients, followed for 1 to 12 years, 10 are asymptomatic, 1 has angina, and 1 died from cancer. All 8 patients who underwent postoperative catheterization had a thick band between the left and right coronary sinus which represented persistent attachment of portions of the aortic valve cusps to residual supravalvular tissue (cusp tuck). This resulted in aortic valvular gradients (23 to 48 mm Hg) in 4 patients and aortic valvular insufficiency in 2 patients. No significant supravalvular gradient was noted. The 20-year experience with supravalvular aortic stenosis reported herein emphasizes a wide range of clinical and morphologic expression, the benefits and limitations of patch aortoplasty, and the importance of postoperative cardiac catheterization, and furthers the understanding of a complex clinical syndrome.

Adolescent↗
PubMedDate not supplied

Major depression in cardiology chest pain patients without coronary artery disease and with panic disorder.

104 patients in a cardiology clinic with atypical or non-anginal chest pain were studied through a structured clinical interview. 43 without coronary artery disease fit diagnostic criteria for panic disorder. 19 (44%) of this group reported a lifetime prevalence of major depression, nine (21%) current and ten (23%) past only. Nine reported that their major depressive episodes had preceded the onset of their panic disorder. On many self-report questionnaire scales the group with a lifetime history of major depression (n = 19) differed significantly from the group with no lifetime history of major depression (n = 24). These differences, however, could be attributed primarily to the group with current major depression. There appears to be a subgroup of panic disorder patients who have current major depression who are more symptomatic than those with panic disorder and past major depression and panic disorder alone. These findings also suggest that the association between panic disorder and depression may remain high outside of psychiatric settings.

Adult↗
PubMedDate not supplied

The effect of myocardial preservation technique on operative mortality in complex valvular heart disease.

Between November, 1964 and January, 1983, 70 consecutive patients underwent primary repair of complex valvular heart disease, defined as repair or replacement of two or more cardiac values alone or with other concomitant cardiac procedures. A total of 163 operative procedures were performed on the 70 patients for an average of 2.33 procedures per patient. Review of these cases allowed the patients to be divided into two distinct groups, those receiving systemic hypothermia and cold potassium cardioplegic arrest of the heart (C) and those having other myocardial preservation techniques (NC). Thirty-three patients received C and are compared with 37 patients who received NC. The two patient groups were comparable when considered for preoperative cardiac index and functional classification though patients in C group were older. In the C group, 10 of 32 patients (31%) had associated coronary artery bypass grafting in contrast to 2 of 37 patients (5.4%) in the NC era. The mortality of the C group was 2 of 33 (6%) vs 14 of 37 (37.8%) in the NC group (P less than .001). Of the 14 deaths in the NC patients, 10 were due to low cardiac output syndrome. While other factors have undoubtedly played a role, improved myocardial preservation by the use of C and attention to coronary artery pathology may have contributed to the improved operative mortality in this group of patients with complex valvular heart disease.

Adult↗