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Biomedical subjects

P F Cohn

Publications and source records attributed to P F Cohn.

At least 19 recordsLinked to original sources
PubMed2001

Direct coronary stenting without balloon or device pretreatment: acute success and long-term results.

Improvements in coronary stents have made planned direct coronary stenting technically feasible, though safety, acute success, cost-effectiveness, and long-term results remain to be determined. Sequential patients eligible for direct stenting were prospectively characterized and treated with either direct or secondary stenting. Major adverse cardiovascular events (MACE) such as cardiac death, myocardial infarction (MI), target vessel ischemia, or revascularization (TVR) were followed for 6 months post-PCI. Enrollment included 128 direct (1.38 lesions/patient) and 69 secondary (1.39 lesions/patient) stented patients. Direct stenting was successful in 99% (with 5% crossover to secondary stenting) without major procedural complications and with a similar rate of vessel wall dissection or no-reflow phenomenon (2.3% vs. 2.1%; P > 0.05) as the secondary stenting group. There was a trend toward less postprocedural CPK-MB elevation in the nonacute MI patients with direct vs. secondary stenting (3% vs. 11%, respectively). At 6 months, there were no statistically significant differences in overall MACE. Direct stenting has a high success rate, low complication rate, and durable long-term results. Procedural cost and time savings, less contrast use and radiation exposure make direct stenting attractive in properly selected patients.

Aged↗
PubMed2001

Acute hemodynamic effects and angina improvement with enhanced external counterpulsation.

Enhanced external counterpulsation (EECP) is an effective noninvasive treatment for coronary artery disease. The mechanism of action is felt to be hemodynamic. The complex hemodynamic effects have been simply quantified by calculating a previously described effectiveness ratio (ER). The EECP Clinical Consortium, a clinical registry of 37 centers, prospectively enrolled 395 chronic stable angina patients (79 women, 316 men, mean age 66 years) to examine the relation of the ER to posttreatment improvement in Canadian Cardiovascular Society angina class (CCS). Women and the elderly underwent planned subgroup analysis. The ER was calculated during the first and last hours of a 35-hour course of EECP treatment. After EECP, CCS improved by at least 1 class in 88% of patients, 87% of men and 92% of women (p = NS), and in 89% of patients < or = 66 years and 88% of patients > 66 years old (p = NS). The initial and final ER were similar in patients with and without improvement in CCS. Significant first-hour ER differences were seen between men and women (0.96 +/- 0.03 vs 0.76 +/- 0.04, p<0.005), and between ages < or = 66 and > 66 years old (1.04 +/- 0.04 vs 0.81 +/- 0.03, p<0.0001). However, all subgroups responded equally well to EECP treatment. EECP is effective in improving CCS in chronic stable angina patients; it has comparable effects in men and women and across a broad range of ages. The hemodynamic effect of EECP (ER) does not predict improvement in CCS and may indicate that other factors, such as neurohormonal changes, may have a significant role in mediating the observed EECP benefits.

Adult↗
PubMed2000

Long-term prognosis of patients with angina treated with enhanced external counterpulsation: five-year follow-up study.

BACKGROUND: Enhanced external counterpulsation (EECP) is a noninvasive treatment for coronary artery disease (CAD) that has been used successfully in patients not responding to medical and/or surgical therapy. HYPOTHESIS: The study was undertaken to evaluate the effect of EECP on long-term prognosis in such patients. METHODS: Major adverse cardiovascular events (MACE) were tracked in 33 patients with CAD treated with EECP. Patients were subgrouped based on whether or not they demonstrated an early improvement in radionuclide stress perfusion imaging (Responders vs. Nonresponders) and followed for MACE over a mean follow-up of 5 years. Patient population characteristics included 73% with multivessel disease; 45% with prior myocardial infarction(s); and 61% who had undergone either coronary artery bypass grafting (CABG) or percutaneous transluminal coronary angioplasty (PTCA), or both. RESULTS: There were 26 of 33 (79%) Responders, and 7 of 33 (21%) Nonresponders. Subsequent MACE over the 5-year follow-up included four deaths and eight patients with cardiovascular events [acute myocardial infarct (4), new CABG or PTCA (6), valve replacement (1), unstable angina (1)]. Nonresponders had significantly (p < 0.01) more MACE (6/7 or 86%) than Responders (6/26 or 23%). Overall, 21 of the 33 (64%) patients remained alive and without MACE and the need for revascularization 5 years post EECP treatment. CONCLUSION: This study suggests that, particularly for the majority of patients demonstrating improvement in radionuclide stress perfusion post treatment, EECP may be an effective long-term therapy.

Aged↗
PubMed1998

Maximizing the hemodynamic benefit of enhanced external counterpulsation.

BACKGROUND: Enhanced external counterpulsation (EECP) has been demonstrated to be an effective treatment for angina and exertional ischemia in patients with coronary disease. HYPOTHESIS: It is hypothesized that the ability of EECP to enhance the recruitment or development of coronary collaterals in coronary artery disease may be determined by the relative magnitude of diastolic augmentation (DA) and systolic unloading (SU). This study examines the relation between the proposed EECP effectiveness ratio (DA/SU), as assessed by finger plethysmography, and changes in descending aortic flow as assessed by Doppler echocardiography in 15 patients during EECP. METHODS: Varying external cuff pressures (0-275 mmHg) were used to generate a range of DA/SU ratios. The effect on aortic antegrade systolic and retrograde diastolic flow was assessed by Doppler echocardiography to determine whether there was an optimal EECP effectiveness ratio that maximizes the hemodynamic effects of EECP. With increasing DA/SU there was an initial positive linear increase in both systolic and diastolic flow volume. Systolic flow maximized at an effectiveness ratio of 1.5 and diastolic flow at a ratio of 2.0 RESULT: Therefore, effectiveness ratios (DA/SU) in the range of 1.5-2.0 are optimal for maximizing the hemodynamic effects of EECP.

Adult↗
PubMed1998

Prior revascularization increases the effectiveness of enhanced external counterpulsation.

BACKGROUND AND HYPOTHESIS: Enhanced external counterpulsation (EECP) is an effective noninvasive treatment for chronic angina. However, its usefulness has been felt to be limited in patients with angiographically demonstrated triple-vessel coronary artery disease (CAD), in accord with the hypothesis that a patent vessel is necessary for transmission of the EECP-augmented coronary artery pressure and volume to the distal coronary vasculature. METHODS: The effect of revascularization [coronary artery bypass grafting (CABG)] prior to EECP was examined in 60 patients with CAD and chronic angina (35 without and 25 with prior CABG). Patients were grouped by the extent of CAD (single-, double-, triple-vessel disease in the unrevascularized group) and by the extent of residual disease (number of stenotic native vessels unbypassed or supplied by a stenotic graft in the CABG group). Significant CAD or graft stenoses were defined as stenoses demonstrating > or = 70% luminal diameter narrowing. Benefit was assessed by improvement in post-EECP treatment over pretreatment radionuclide stress testing. RESULTS: Radionuclide stress testing demonstrated a comparable favorable response (80 vs. 71%; p = NS) in patients with prior CABG versus unrevascularized patients. Enhanced external counterpulsation was highly and comparably effective in patients with unrevascularized native single- and double-vessel CAD and in patients with CABG with residual single- and double-vessel CAD (88 vs. 80%; p = NS). Most notably, CABG significantly increased the beneficial response to EECP in those patients with triple-vessel CAD and stenotic grafts compared with unrevascularized patients with triple-vessel CAD (80 vs. 22%; p < 0.05 by chi-square test). CONCLUSION: The results suggest a new role for EECP as an effective treatment for post CABG ischemia, despite extensive CAD and even in the presence of stenotic grafts.

Aged↗
PubMed1998

Treatment of chronic myocardial ischemia: rationale and treatment options.

A rational approach to the treatment of chronic myocardial ischemia requires an appreciation of the pathophysiology of coronary artery disease and the treatment options available. Any factor that causes an imbalance between myocardial oxygen supply and demand can provoke ischemia. Myocardial oxygen requirements rise with increases in heart rate, contractility, or left ventricular wall stress. Myocardial oxygen supply is determined by coronary artery flow and myocardial oxygen extraction. Anti-anginal medications are the mainstay of anti-ischemic management and act to correct the balance between myocardial supply and demand by increasing coronary blood flow, reducing myocardial oxygen requirements, or both. These medications include nitrates (which act principally by venous vasodilation, but also probably by coronary dilation), beta-blockers (which act mainly by reducing heart rate and cardiac contractility), and calcium channel blockers (which act principally by arterial and coronary vasodilation). The choice of therapy and its effectiveness depend on the underlying cause of ischemia. The complimentary mechanisms of action of these drug classes suggest that their use in combination may result in a greater reduction in myocardial oxygen demand than that achieved with monotherapy. In addition, the pharmacological actions of some of these drugs may serve to offset the undesirable side effects associated with others, for example, the reflex tachycardia produced by some calcium channel blockers may be offset by beta-blocker therapy. Finally, aspirin and lipid-lowering drugs and the potential role for anti-oxidants must also be considered in combination therapy. Invasive techniques for myocardial ischemic management, such as coronary artery bypass and coronary angioplasty, improve myocardial oxygen supply by relieving or circumventing the atherosclerotic obstruction responsible for ischemia. Surgery is the preferred technique in patients with certain medical conditions, for example, those with triple-vessel disease, but is not recommended in patients with mild angina unless left main artery disease is present.

Animals↗
PubMed1997

Enhanced external counterpulsation as an adjunct to revascularization in unstable angina.

Enhanced external counterpulsation (EECP) is an effective noninvasive treatment for chronic stable angina. Despite intensive risk factor modification, a patient required two surgical coronary revascularizations and seven multivessel angioplasties over a 26-month period, demonstrating recurrent unstable angina and persistent thallium perfusion defects despite revascularization. Post EECP, angina was relieved, thallium defects were resolved and the patient has remained asymptomatic for 36 months.

Angina, Unstable↗
PubMed1997

Rationale for the use of calcium antagonists in the treatment of silent myocardial ischemia.

Silent myocardial ischemia, whether it occurs at rest or during exercise, is associated with an unfavorable prognosis and may lead to sudden cardiac death. Agents used to treat silent myocardial ischemia have included nitrates, beta-blockers, and calcium antagonists (CAs). Despite treatment with traditional anti-ischemic agents, studies have shown that up to 40% of patients who receive what is considered to be clinically optimal antianginal therapy continue to have daily episodes of silent myocardial ischemia. The use of nitrates and beta-blockers is sometimes confounded by issues of tolerance and tolerability. Although the CAs have been found to be effective in decreasing the duration and frequency of episodes of silent ischemia, in general beta-blockers produce a greater reduction in these variables. Thus a need for effective and tolerable anti-ischemic agents persists. A new class of CAs, the tetralol derivatives, may show promise in this regard. The first of this new class, mibefradil, is characterized by selective blockade of T-type calcium-ion channels and has been shown in a few studies to reduce the frequency and duration of asymptomatic ischemic episodes in patients with stable exertional angina pectoris. Large-scale clinical trials are necessary before the efficacy and tolerability of this new CA can be compared fully with those of the beta-blockers and currently available CAs.

Adrenergic beta-Antagonists↗
PubMed1997

Pharmacological treatment of ischaemic heart disease. Monotherapy vs combination therapy.

Non-invasive treatment continues to be the mainstay of anti-ischaemic therapy. The imbalance between myocardial oxygen supply and demand provides the basis for myocardial ischaemia, which may present as symptomatic, asymptomatic or, in most cases, a mixture of the two. Both symptomatic and silent ischaemia are major prognostic indicators in patients with coronary artery disease and treatment should therefore be directed towards both the amelioration of symptoms and the resolution of the signs of ischaemia. Anti-ischaemic therapy may decrease oxygen demand, increase myocardial oxygen supply, or both. Interventional therapies, such as percutaneous transluminal coronary angioplasty and bypass grafting, improve supply but do not alter demand. Drug therapy is associated with a variety of effects upon both supply and demand, depending upon the agent used. Nitrates alter both myocardial oxygen supply and demand, while beta-blockers decrease myocardial oxygen demand. Calcium channel blockers reduce after load and myocardial contractility and, thus, lower oxygen demand, while the coronary artery relaxation that occurs in response to their use acts to increase supply. The use of combination therapy is considered by many to be the most rational approach to the treatment of myocardial ischaemia, in that it allows maximal reduction in demand and increase in supply.

Adrenergic beta-Antagonists↗
PubMed1996

Can angiographic findings predict which coronary patients will benefit from enhanced external counterpulsation?

Enhanced external counterpulsation is an effective treatment for chronic angina. Theoretical considerations predict greatest benefit in patients with at least 1 patent conduit in this group of 50 patients (all of whom improved clinically). Improvement in radionuclide stress perfusion imaging was seen in 80% of treated patients and was inversely related to extent of coronary disease.

Aged↗
PubMed1994

Silent myocardial ischemia: to treat or not to treat?

The risk of infarction and sudden death is considerable in patients with silent ischemia, whether it occurs alone or is interspersed with episodes of angina. The ischemic activity can be modified or even abolished, most effectively with beta-blocker and nitrate therapy. But it is not yet clear whether treatment improves outcome, although the limited available data suggest that it does.

Adrenergic beta-Antagonists↗
PubMed1994

Concomitant use of nitrates, calcium channel blockers, and beta blockers for optimal antianginal therapy.

Despite the introduction of new mechanical techniques for revascularization, pharmacologic therapy continues to be the mainstay of antianginal therapy. The conventional antianginal medications, which include nitrates, beta blockers, and calcium channel blockers, act to correct the imbalance between myocardial supply and demand by increasing coronary blood flow, reducing myocardial oxygen requirements, or both. All three are appropriate for the management of angina caused by a fixed coronary obstruction, but nitrates and calcium channel blockers, which not only reduce demand but also increase supply, are preferred in cases of angina believed to involve a significant increase in vasomotor tone. Because of the different yet complementary mechanisms of action of the three classes of anti-ischemic drugs, use of these agents in combination is a rational approach to the treatment of angina unresponsive to monotherapy. Such combinations have been shown to enhance the therapeutic response achieved with single-agent therapy. In addition, the pharmacologic action of one of the components of the combination regimen may serve to offset side effects typically associated with the other.

Adrenergic beta-Antagonists↗
PubMed1994

Effects of captopril therapy after late reperfusion on left ventricular remodeling after experimental myocardial infarction.

Reperfusion that is too late to salvage ischemic myocardium reduces early infarct expansion, and captopril therapy favorably alters long-term left ventricular remodeling. To study whether the beneficial effects of these two therapies are additive, we examined the effects of captopril therapy after late reperfusion on left ventricular remodeling after acute myocardial infarction. Female Sprague-Dawley rats (n = 67) were randomly assigned to one of four groups: group 1, sham surgery and no treatment; group 2, left coronary artery ligation and no treatment (myocardial infarction [r MI]); group 3, left coronary artery ligation, reperfusion 2 hours later, and no treatment (late reperfusion [LR]); and group 4, left coronary artery ligation, reperfusion 2 hours later, and captopril treatment (LR-Cap). Captopril therapy (2 gm/L of drinking water) was begun in the LR-Cap group in the immediate post-operative period and continued for 20 days. Twenty-one days postoperatively, hemodynamic measurements were made before and after volume loading. The rats were killed, their hearts were removed, and passive pressure-volume curves were obtained. The hearts were then fixed at a constant pressure for morphometric analysis. Compared with the MI group, the LR group had a lower expansion index and a higher thinning ratio. There were no differences in hemodynamics, left ventricular volumes, or other morphometric indexes between the two groups. Compared with the MI and LR groups, the LR-Cap group had lower peak left ventricular end-diastolic pressure, lower left ventricular volume, lower left and right ventricular weights, and a leftward shift of pressure-volume curves.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗